Topic Editors

School of Water Conservancy Engineering, Zhengzhou University, Zhengzhou 450001, China
Prof. Dr. Baosong Ma
School of Civil Engineering, Sun Yat-Sen University, Guangzhou 510275, China
Prof. Dr. Qunfang Hu
Urban Mobility Institute, Tongji University, Shanghai, China
Institute of Earthquake Engineering, Faculty of Infrastructure Engineering, Dalian University of Technology, Dalian 116024, China
Prof. Dr. Niannian Wang
School of Water Conservancy Engineering, Zhengzhou University, Zhengzhou 450001, China
Dr. Cong Zeng
Faculty of Engineering, China University of Geosciences (Wuhan), Wuhan, China
China-Pakistan Belt and Road Joint Laboratory on Smart Disaster Prevention of Major Infrastructures, Southeast University, Nanjing 210096, China

Pipeline and Underground Space Technology

Abstract submission deadline
closed (30 October 2023)
Manuscript submission deadline
closed (30 December 2023)
Viewed by
40431

Topic Information

Dear Colleagues,

The development of underground space technology meets the needs of rapid urban development, such as easing traffic pressure, promoting economic development, and realizing resource sharing. With an increase in the age of service, underground engineering occurs a variety of damages, such as deformation, water gushing, collapse, etc. These damages cause huge economic losses and casualties. Therefore, the detection and monitoring of the long-term performance in addition to the timely repair of underground engineering become a major concern. This Topic aims to collect the latest advances and trends in the field of intelligent detection and trenchless technology of underground engineering.

In this Topic, we invite you to contribute original research articles and reviews on any aspects related to the intelligent detection and trenchless technology of underground engineering, including, but not limited to:

AI-based intelligent sensing and monitoring, damage detection, diagnosis and characterization of pipeline damages, in situ field test methods, nondestructive techniques, laboratory tests, and analysis.

The geoinvestigation, geomechanical analysis, design and modeling, construction and monitoring, and maintenance as well as rehabilitation of pipelines in addition to large underground and earth-sheltered structures.

The planning, development, and operation of underground space and underground space environments, such as architecture, safety and comfort, and human–space interaction.

The installation and rehabilitation of underground pipelines, ducts, and cables using pipe jacking, microtunneling, and other forms of trenchless technologies.

Prof. Dr. Hongyuan Fang
Prof. Dr. Baosong Ma
Prof. Dr. Qunfang Hu
Prof. Dr. Xin Feng
Prof. Dr. Niannian Wang
Dr. Cong Zeng
Prof. Dr. Hongfang Lu
Topic Editors

Keywords

  • pipeline
  • underground space technology
  • intelligent detection
  • trenchless technology
  • performance evaluation

Participating Journals

Journal Name Impact Factor CiteScore Launched Year First Decision (median) APC
Applied Sciences
applsci
2.7 4.5 2011 16.9 Days CHF 2400
Buildings
buildings
3.8 3.1 2011 14.6 Days CHF 2600
Geosciences
geosciences
2.7 5.2 2011 23.6 Days CHF 1800
Machine Learning and Knowledge Extraction
make
3.9 8.5 2019 19.9 Days CHF 1800
Materials
materials
3.4 5.2 2008 13.9 Days CHF 2600
Sensors
sensors
3.9 6.8 2001 17 Days CHF 2600

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Published Papers (32 papers)

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22 pages, 3893 KiB  
Article
Finite Element Analysis of Combined Energy Piles with Long and Short Heat Exchanger Tubes
Appl. Sci. 2023, 13(23), 12579; https://doi.org/10.3390/app132312579 - 22 Nov 2023
Viewed by 477
Abstract
To improve the heat exchange effect of energy piles in coastal areas, a new energy pile with a combination of long and short heat exchanger tubes is proposed. This technology combines the characteristics of implanted pile construction and arranges heat exchanger tubes of [...] Read more.
To improve the heat exchange effect of energy piles in coastal areas, a new energy pile with a combination of long and short heat exchanger tubes is proposed. This technology combines the characteristics of implanted pile construction and arranges heat exchanger tubes of different lengths inside and outside the precast pipe pile, which can make full use of the geological conditions in coastal areas. Finite element analysis was applied for a project in a deep, soft soil ground to study the effectiveness of the new combined energy pile technology. The influences of the combined heat exchanger tubes and groundwater seepage conditions on the heat transfer and stress state of the energy pile were analyzed. The results show that the deformation and internal force of the pile body are closely related to temperature change. The temperature change is determined by heat transfer, which is closely related to the arrangement of heat exchanger tubes and underground water flow. With the increase of groundwater seepage velocity, the heat taken away by the heat exchanger tubes gradually increases; thus, the heat exchange between the heat exchanger tubes and the pile body decreases. The inner heat exchanger tube of the pile leads to an increase in heat exchange. However, as the length of the inner heat exchanger tube increases from 40 m to 80 m, the heat exchange decreases. The research results provide technical support for further development of the new energy pile technology. Full article
(This article belongs to the Topic Pipeline and Underground Space Technology)
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20 pages, 7049 KiB  
Article
Experimental and Numerical Study on the Low Velocity Impact Behavior of ABR Pipe
Appl. Sci. 2023, 13(20), 11390; https://doi.org/10.3390/app132011390 - 17 Oct 2023
Viewed by 564
Abstract
The low velocity impact load on pipes during transportation, construction and operation will cause pipeline damage and lay hidden dangers for the safety of pipeline engineering. To study the low velocity impact performance of pipes made of acrylate polymer blended with polyvinyl chloride [...] Read more.
The low velocity impact load on pipes during transportation, construction and operation will cause pipeline damage and lay hidden dangers for the safety of pipeline engineering. To study the low velocity impact performance of pipes made of acrylate polymer blended with polyvinyl chloride resin for water supply (ABR), 20 sets of specimens with different heights and different masses of drop hammer were carried out to study the mechanical properties of ABR pipes. Based on the impact time curve, the energy dissipation capacity and impact peak value of ABR pipe specimens were analyzed, and the empirical calculation formula of impact force peak based on the test data is obtained by the dimensional analysis method, with a relative error ranging from −7.8% to 4.1%. Moreover, the finite element numerical simulation of ABR pipe specimens subjected to impact load is carried out, and the strain development law and failure mode of the pipe under low-speed impact load are analyzed. Therefore, the calculation formula of peak impact force and failure mode proposed in this paper can provide safety assessment methods for pipeline engineering designers and constructors. Full article
(This article belongs to the Topic Pipeline and Underground Space Technology)
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21 pages, 4613 KiB  
Article
An Analytical Method for Mechanical Analysis of Offshore Pipelines during Lifting Operation
Materials 2023, 16(20), 6685; https://doi.org/10.3390/ma16206685 - 13 Oct 2023
Viewed by 810
Abstract
The lifting operation of offshore pipelines is an important step in ocean pipeline engineering. An effective analytical method is developed for investigating the mechanical properties of the pipeline based on mechanical, physical, and geometric relationships. By using the shooting and the secant methods [...] Read more.
The lifting operation of offshore pipelines is an important step in ocean pipeline engineering. An effective analytical method is developed for investigating the mechanical properties of the pipeline based on mechanical, physical, and geometric relationships. By using the shooting and the secant methods to transform the boundary value problem into an initial value one and then solving them with the Runge–Kutta method, the deformation and mechanical properties of the pipeline are calculated. Furthermore, based on the Det Norske Veritas (DNV) offshore standard, the mechanical properties of the pipeline are checked. The finite element method (FEM) by Orcaflex is employed to verify the accuracy of the analytical model. The effects of some factors such as the current velocity and lifting point position on the mechanical properties of the pipeline are analyzed based on the analytical model. The results indicate that the change in current velocity during the lifting process has a minimal effect on the pipeline, but the change in lifting point position significantly affects the deformation and mechanical properties of the pipeline. Full article
(This article belongs to the Topic Pipeline and Underground Space Technology)
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18 pages, 8634 KiB  
Article
Pseudo-Static Tests on Top Joints of Hybrid Precast Utility Tunnel
Buildings 2023, 13(10), 2567; https://doi.org/10.3390/buildings13102567 - 11 Oct 2023
Cited by 1 | Viewed by 519
Abstract
This paper introduces a new type of hybrid precast MUT, consisting of precast composite top slab and double-skin sidewalls with reserved rebar. The seismic behavior of the top joints was examined through pseudo-static tests. Four full-scale specimens, including both exterior and interior precast [...] Read more.
This paper introduces a new type of hybrid precast MUT, consisting of precast composite top slab and double-skin sidewalls with reserved rebar. The seismic behavior of the top joints was examined through pseudo-static tests. Four full-scale specimens, including both exterior and interior precast joints, in addition to two corresponding cast-in-place (CIP) joints, were fabricated and subjected to reversed cyclic loading. The results showed that both the precast and CIP joints exhibited flexure failure, characterized by the formation of a plastic hinge at the end of the sidewall. The hysteresis curves of both precast and CIP joints exhibited comparable shapes and quantities of hysteresis loops. The load-carrying capacities for exterior precast joints and corresponding CIP joints were 141.25 kN and 143.5 kN, exhibiting a difference of less than 1.6%. The load-carrying capacities for interior precast and corresponding CIP joints were 60.5 kN and 62.75 kN, displaying a variance of less than 3.6%. The precast specimens demonstrated comparable levels of ductility, energy dissipation, and structural integrity as the CIP specimens. These findings provide validation for designing and analyzing the hybrid precast utility tunnel using identical principles and models as applied CIP structures. Full article
(This article belongs to the Topic Pipeline and Underground Space Technology)
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27 pages, 9164 KiB  
Article
Algorithm for Automatic Rod Feeding and Positioning Error Compensation for Underground Drilling Robots in Coal Mines
Sensors 2023, 23(17), 7530; https://doi.org/10.3390/s23177530 - 30 Aug 2023
Viewed by 589
Abstract
In the pursuit of automating the entire underground drilling process in coal mines, the automatic rod feeding technology of drilling robots plays a crucial role. However, the current lack of positional accuracy in automatic rod feeding leads to frequent accidents. To address this [...] Read more.
In the pursuit of automating the entire underground drilling process in coal mines, the automatic rod feeding technology of drilling robots plays a crucial role. However, the current lack of positional accuracy in automatic rod feeding leads to frequent accidents. To address this issue, this paper presents an algorithm for compensating positioning errors in automatic rod feeding. The algorithm is based on a theoretical mathematical model and manual teaching methods. To enhance the positioning accuracy, we first calibrate the pull rope sensor to correct its measurement precision. Subsequently, we establish a theoretical mathematical model for rod feeding positions by employing spatial coordinate system transformations. We determine the target rod feeding position using a manual teaching-based approach. Furthermore, we analyze the relationship between the theoretical rod delivery position and the target rod delivery position and propose an anisotropic spatial difference compensation technique that considers both distance and direction. Finally, we validate the feasibility of our proposed algorithm through automatic rod feeding tests conducted on a coal mine underground drilling robot. The results demonstrate that our algorithm significantly improves the accuracy of rod feeding positions for coal mine underground drilling robots. Full article
(This article belongs to the Topic Pipeline and Underground Space Technology)
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17 pages, 5616 KiB  
Article
Deformation Analysis and Reinforcement Effect of Tunnel Pile Excavation of a Subway Station in a Weak Stratum
Buildings 2023, 13(8), 1943; https://doi.org/10.3390/buildings13081943 - 30 Jul 2023
Viewed by 759
Abstract
The underground hole pile excavation method causes a large vertical displacement in a weak stratum, which affects the safety of structures. For the first time, the hole pile excavation method is being used to construct a subway station in South China, and the [...] Read more.
The underground hole pile excavation method causes a large vertical displacement in a weak stratum, which affects the safety of structures. For the first time, the hole pile excavation method is being used to construct a subway station in South China, and the settlement law of the area is not clear. It is important to clarify the deformation law of the hole pile excavation method in weak strata and the effect achieved by appropriate reinforcement measures. In this paper, by establishing a three-dimensional finite element model of the structure–soil contact element and combining it with the field monitoring data, the law of surface settlement caused by the hole pile excavation method with different thicknesses of the weak stratum has been studied. In order to improve the stability of the surrounding rock and reduce the vertical deformation of the surface, the Metro Jet System (MJS) is used to form inclined piles in the area of large surface deformation, and the effect after reinforcement was evaluated. The results show that as the weak layer thickness ratio increases, the surface settlement also increases. In the case of no reinforcement, a vertical settlement of 116 mm can be achieved when the thickness of the weak layer is 14 m. The vault of the tunnel is in the weak layer and the deformation is obvious. When the vault is not in the weak layer, the settlement is obviously reduced. After MJS pile reinforcement, under the action of soil extrusion, the self-stability of the surrounding rock is strengthened, and the oblique jet grouted pile forms a stable ‘triangle’. The vertical settlement value is basically stable at around 30 mm, which meets the requirements of the regulations. If the tunnel is not reinforced, the self-stability of the surrounding rock above the tunnel arch is poor and the maximum settlement is at the surface. After MJS reinforcement, the maximum settlement is at the vault. The vertical settlement of the ground surface can be effectively controlled by using the MJS pile forming technology in the middle of the tunnel pile driving method. Full article
(This article belongs to the Topic Pipeline and Underground Space Technology)
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24 pages, 5838 KiB  
Article
Evaluation of Excavation Ergonomics of Drill and Blast Method Based on Game Theory G2-EW-TOPSIS Model
Appl. Sci. 2023, 13(12), 7205; https://doi.org/10.3390/app13127205 - 16 Jun 2023
Viewed by 1017
Abstract
The demand for tunnel construction continues to grow by leaps and bounds. Therefore, tunnel mechanization construction is receiving more and more attention for improving excavation ergonomics. To enhance the scientific and comprehensive evaluation results of tunnel drilling and blasting method excavation ergonomics, a [...] Read more.
The demand for tunnel construction continues to grow by leaps and bounds. Therefore, tunnel mechanization construction is receiving more and more attention for improving excavation ergonomics. To enhance the scientific and comprehensive evaluation results of tunnel drilling and blasting method excavation ergonomics, a set of evaluation methods of tunnel drilling and blasting method excavation ergonomics based on the game theory G2-EW-TOPSIS model is proposed. From the three dimensions of drilling efficiency, construction process duration, and synergistic influence factors, a tunnel drilling and blasting construction ergonomics evaluation index system consisting of 11 indicators such as perimeter hole drilling efficiency, drilling duration, construction quality, and comprehensive cost is constructed. The subjective and objective weights of evaluation indicators are calculated by using the improved sequential relationship analysis method (G2 method) and entropy weight method, respectively, and the combination weights are carried out by using game theory method (GTM) with the Nash equilibrium as the goal. The indices are classified into five grades: excellent (I), good (II), average (III), rather poor (IV), and poor (V), according to the daily tunnel construction. The excavation ergonomics index to be evaluated is calculated using the combined weights, and the comprehensive evaluation index of excavation ergonomics to be evaluated is calculated using the technique for order preference by similarity to an ideal solution (TOPSIS). The proposed rating model was used to analyze the excavation ergonomics of the Shangtianling Tunnel in the Chizhou–Huangshan High-Speed Railway using jumbo drills (JD) and drilling machines (DM) in large- and small-mileage construction, respectively, and to obtain the excavation ergonomics rating and comprehensive evaluation rating of each evaluation object. The research results show that the established excavation ergonomics evaluation model can effectively identify the main factors affecting the excavation ergonomics of the drill and blast method, and has a certain reference value. Full article
(This article belongs to the Topic Pipeline and Underground Space Technology)
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15 pages, 43367 KiB  
Article
Experimental Study on the Azimuthal-Transmitting Transducer of Acoustic Logging
Sensors 2023, 23(6), 3247; https://doi.org/10.3390/s23063247 - 19 Mar 2023
Viewed by 1085
Abstract
Azimuthal acoustic logging can survey the downhole formation more accurately, and the acoustic source is the crucial component of the downhole acoustic logging tool with azimuthal resolution characteristics. To realize downhole azimuthal detection, assembling multiple transmitting piezoelectric vibrators in the circumferential direction is [...] Read more.
Azimuthal acoustic logging can survey the downhole formation more accurately, and the acoustic source is the crucial component of the downhole acoustic logging tool with azimuthal resolution characteristics. To realize downhole azimuthal detection, assembling multiple transmitting piezoelectric vibrators in the circumferential direction is necessary, and the performance of azimuthal-transmitting piezoelectric vibrators needs attention. However, effective heating test and matching methods are not yet developed for downhole multi-azimuth transmitting transducers. Therefore, this paper proposes an experimental method to comprehensively evaluate downhole azimuthal transmitters; furthermore, we analyze the azimuthal-transmitting piezoelectric vibrator parameters. This paper presents a heating test apparatus and studies the admittance and driving responses of the vibrator at different temperatures. The transmitting piezoelectric vibrators showing a good consistency in the heating test were selected, and an underwater acoustic experiment was performed. The main lobe angle of the radiation beam, horizontal directivity, and radiation energy of the azimuthal vibrators and azimuthal subarray are measured. The peak-to-peak amplitude radiated from the azimuthal vibrator and the static capacitance increase with an increase in temperature. The resonant frequency first increases and then decreases slightly with an increase in temperature. After cooling to room temperature, the parameters of the vibrator are consistent with those before heating. Hence, this experimental study can provide a foundation for the design and matching selection of azimuthal-transmitting piezoelectric vibrators. Full article
(This article belongs to the Topic Pipeline and Underground Space Technology)
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14 pages, 8295 KiB  
Article
Diffusion Model of Cement Slurry in Porous Media Considering Porosity Variation and Percolation Effect
Appl. Sci. 2023, 13(3), 1919; https://doi.org/10.3390/app13031919 - 02 Feb 2023
Cited by 1 | Viewed by 1060
Abstract
The porosity of porous media is a key factor affecting cement slurry diffusion. In this paper, a theoretical model of cement slurry diffusion in porous media considering the variation of porosity is proposed. The model is validated through comparison with the experimental results [...] Read more.
The porosity of porous media is a key factor affecting cement slurry diffusion. In this paper, a theoretical model of cement slurry diffusion in porous media considering the variation of porosity is proposed. The model is validated through comparison with the experimental results in the literature. The influence of injection parameters (i.e., the water–cement ratio and the pore fractal dimension) on the porosity and strength of porous media is analyzed. The results indicate that: under the same pore fractal dimension, the porosity of the specimen increases gradually with the increase in diffusion distance, and the rate increases rapidly in the later stage. However, when the fractal dimension of porosity increases to 2.1, the porosity of the consolidated body after grouting does not change with the diffusion distance. The water–cement ratio also affects the porosity of the sample. At a distance below 1.0 m, the sample porosity is larger at a larger water–cement ratio of 1.5. When the distance is more than 1.0 m, the smaller the porosity decreases with increasing water–cement ratios. With the increase in distance, the compressive strength of the specimen first decreases slowly, and then rapidly from 90 kPa to 0 kPa. This is further verified by the pore variation law obtained by SEM. The model is applied to selecting grouting parameter design in road maintenance. The pavement deflection after grouting is effectively reduced, verifying the theoretical model’s applicability. Full article
(This article belongs to the Topic Pipeline and Underground Space Technology)
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24 pages, 7083 KiB  
Article
Walking Speed in a Motorbike Lane Considering the Density of Evacuees and Motorbikes
Appl. Sci. 2022, 12(24), 12580; https://doi.org/10.3390/app122412580 - 08 Dec 2022
Cited by 1 | Viewed by 790
Abstract
In countries with a high motorbike utilization rate, road tunnels can feature motorbike lanes, bringing an additional risk to evacuation from tunnels during a fire or emergency. To better understand the walking speed in motorbike lanes to enhance risk assessment in tunnels, in [...] Read more.
In countries with a high motorbike utilization rate, road tunnels can feature motorbike lanes, bringing an additional risk to evacuation from tunnels during a fire or emergency. To better understand the walking speed in motorbike lanes to enhance risk assessment in tunnels, in the present study, we conducted evacuation experiments to investigate the influence of motorbike and evacuee density on the walking speed of motorbike users. According to the experimental results, the walking speed was slightly reduced even when the evacuee density was relatively lower (around 0.1 person/m2). To further analyze the influence of motorbikes in the lane, the walking speed decreased significantly with the increase in motorbike density. The decrease in walking speed presented an exponential relationship with evacuee and motorbike density. Considering this exponential relationship, nonlinear regression was applied to estimate the parameters of the walking speed model. The proposed model consisting of the evacuee density, motorbike density, and free walking speed as variables can serve as an approach to describe the walking speed of motorbike lane evacuation in tunnels. Full article
(This article belongs to the Topic Pipeline and Underground Space Technology)
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16 pages, 12958 KiB  
Article
Physical Simulation of Ultrasonic Imaging Logging Response
Sensors 2022, 22(23), 9422; https://doi.org/10.3390/s22239422 - 02 Dec 2022
Cited by 1 | Viewed by 984
Abstract
Ultrasonic imaging logging can visually identify the location, shape, dip angle and orientation of fractures and holes. The method has not been effectively applied in the field; one of the prime reasons is that the results of physical simulation experiments are insufficient. The [...] Read more.
Ultrasonic imaging logging can visually identify the location, shape, dip angle and orientation of fractures and holes. The method has not been effectively applied in the field; one of the prime reasons is that the results of physical simulation experiments are insufficient. The physical simulation of fracture and hole response in the laboratory can provide a reference for the identification and evaluation of the underground geological structure. In this work, ultrasonic scanning experiments are conducted on a grooved sandstone plate and a simulated borehole and the influence of different fractures and holes on ultrasonic pulse echo is studied. Experimental results show that the combination of ultrasonic echo amplitude imaging and arrival time imaging can be used to identify the fracture location, width, depth and orientation, along with accurately calculating the fracture dip angle. The evaluated fracture parameters are similar to those in the physical simulation model. The identification accuracy of the ultrasonic measurement is related to the diameter of the radiation beam of the ultrasonic transducer. A single fracture with width larger than or equal to the radiation beam diameter of the ultrasonic transducer and multiple fractures with spacing longer than or equal to the radiation beam diameter can be effectively identified. Full article
(This article belongs to the Topic Pipeline and Underground Space Technology)
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18 pages, 4896 KiB  
Article
The Effect of Microbiologically Induced Concrete Corrosion in Sewer on the Bearing Capacity of Reinforced Concrete Pipes: Full-Scale Experimental Investigation
Buildings 2022, 12(11), 1996; https://doi.org/10.3390/buildings12111996 - 16 Nov 2022
Cited by 5 | Viewed by 1626
Abstract
The main part of sewer pipelines is commonly made up of precast reinforced concrete pipes (RCPs). However, they often suffer from microbiologically induced concrete corrosion (MICC), which has made them less durable than expected. In this study, three-edge bearing tests (TEBT) are performed [...] Read more.
The main part of sewer pipelines is commonly made up of precast reinforced concrete pipes (RCPs). However, they often suffer from microbiologically induced concrete corrosion (MICC), which has made them less durable than expected. In this study, three-edge bearing tests (TEBT) are performed on full-scale RCPs with preset wall losses to determine how MICC influences their bearing performance. For this purpose, several bearing indices such as D-load, peak load, ultimate load, ring deflection, ring stiffness, and failure energy are presented or specified to characterize the load-carrying capacity, stiffness, and toughness of these RCPs. It is found that crown concrete corrosion hardly changes the mechanical behavior of the first elastic zone of RCPs, so that D-load is not affected, but it shortens the crack propagation zone significantly, leading to a reduction in ultimate and peak loads. Furthermore, RCPs’ ring stiffness and toughness are negatively correlated to thickness of wall loss, while the transverse deformability of the ring cross-section is positively correlated with it. Additionally, it was found that crown corrosion affects the ultimate load of different sizes of RCP in different ways. The 2000 mm RCP is affected the most, with a 50 percent reduction in ultimate load. The 1000 mm RCP follows, with a 36 percent reduction, and the 1500 mm RCP has a reduction of less than 20 percent. This research contributes to comprehending the degradation of in-service sewage pipes, hence informing decision making on sewer maintenance and rehabilitation. Full article
(This article belongs to the Topic Pipeline and Underground Space Technology)
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16 pages, 8943 KiB  
Brief Report
Pipe Spatter Detection and Grinding Robot
Appl. Sci. 2022, 12(21), 11045; https://doi.org/10.3390/app122111045 - 31 Oct 2022
Viewed by 1207
Abstract
This paper proposes a robotic system that automatically identifies and removes spatters generated while removing the back-bead left after the electric resistance welding of the outer and inner surfaces during pipe production. Traditionally, to remove internal spatters on the front and rear of [...] Read more.
This paper proposes a robotic system that automatically identifies and removes spatters generated while removing the back-bead left after the electric resistance welding of the outer and inner surfaces during pipe production. Traditionally, to remove internal spatters on the front and rear of small pipes with diameters of 18–25 cm and lengths of up to 12 m, first, the spatter locations (direction and length) are determined using a camera that is inserted into the pipe, and then a manual grinder is introduced up to the point where spatters were detected. To optimize this process, the proposed robotic system automatically detects spatters by analyzing the images from a front camera and removes them, using a grinder module, based on the spatter location and the circumferential coordinates provided by the detection step. The proposed robot can save work time by reducing the required manual work from two points (the front and back of the pipe) to a single point. Image recognition enables the detection of spatters with sizes between 0.1 and 10 cm with 94% accuracy. The internal average roughness, Ra, of the pipe was confirmed to be 1 µm or less after the spatters were finally removed. Full article
(This article belongs to the Topic Pipeline and Underground Space Technology)
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18 pages, 7641 KiB  
Article
Full-Scale Test and Bearing Capacity Evaluation of Large Diameter Prestressed Concrete Cylinder Pipe under Internal Water Pressure
Buildings 2022, 12(11), 1791; https://doi.org/10.3390/buildings12111791 - 26 Oct 2022
Cited by 1 | Viewed by 1276
Abstract
In practical applications, the safe operation of large-diameter prestressed concrete cylinder pipes (PCCPs) depends on the loading performance under internal water pressure. However, there is lack of damage tests for the full-scale large-diameter PCCPs due to economic cost and experimental difficulty. In this [...] Read more.
In practical applications, the safe operation of large-diameter prestressed concrete cylinder pipes (PCCPs) depends on the loading performance under internal water pressure. However, there is lack of damage tests for the full-scale large-diameter PCCPs due to economic cost and experimental difficulty. In this paper, a full-scale PCCP with diameter of 3.2 m was tested to verify the bearing capacity for applying to an actual water transfer project. The PCCP was designed by the limit state method and manufactured in a prefabrication plant. During the test, the strains of concrete, prestressed steel wire, and mortar were detected to evaluate the limit state of bearing capacity under internal water pressure. Based on the test results and the strain analysis at the limit state, it was found that when the water pressure reached 1.9 MPa, the concrete outside the steel cylinder was at the serviceability limit state, and the prestressed steel wire was in elastic, while some protective mortar exceeded the serviceability limit state due to the appearance of visible cracks. A good accuracy of the theoretical calculation with the predicted results lower about 9.4% and 8% than tested pressures at decompression and cracking states. Moreover, the cracking pressure of concrete and bursting pressure of pipe were 2.5 and 6 times of the working pressure according to the calculation results. This indicated that the PCCP used in this study had sufficient safety in actual operation. However, it should be noted that the tensile control strain of mortar may be overestimated by the current code. Full article
(This article belongs to the Topic Pipeline and Underground Space Technology)
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19 pages, 6850 KiB  
Article
Experimental Study on External Loading Performance of Large Diameter Prestressed Concrete Cylinder Pipe
Buildings 2022, 12(10), 1740; https://doi.org/10.3390/buildings12101740 - 19 Oct 2022
Cited by 5 | Viewed by 1409
Abstract
A prestressed concrete cylinder pipe (PCCP) is created with a complex composition of concrete core, welded steel cylinder, prestressed steel wire, protective mortar and anti-corrosion coating. Due to the economy and complexity of structural prototype tests, the ultimate loading test on PCCP is [...] Read more.
A prestressed concrete cylinder pipe (PCCP) is created with a complex composition of concrete core, welded steel cylinder, prestressed steel wire, protective mortar and anti-corrosion coating. Due to the economy and complexity of structural prototype tests, the ultimate loading test on PCCP is rarely conducted. In this paper, the three-edge bearing test was carried out on a 3.2 m diameter PCCP with embedded steel cylinder. The strains of concrete core, prestressed steel wire and protective mortar were monitored, and the distribution and width of the concrete cracks were recorded. The test results show that the cracking on the inside concrete at the crown zone occurred before those on the invert zone of the pipe. The prestressed steel wire postponed the tensile stress of out-side concrete at the springing line until subjected to the calculated cracking load (Pc). Due to the moment redistribution caused by the cracking on the inside of the concrete at the crown/invert, the protective mortar at the springing line was cracked at 1.2 Pc and exhibited visible cracking after 1.4 Pc. The prestressed steel wire reached the elastic and strength limit states of 1.4 Pc and 1.6 Pc, respectively. The PCCP designed by the limit state design method can resist the increased external loads after reaching the serviceability limit state. The final failure load of the test pipe is greater than 1.6 Pc, and there is sufficient safety in actual operation. Due to the fact that the damage to the concrete at the crown/invert zone may become a fuse of PCCP failure, the tensile stress of the inside concrete at the crown/invert zone of the PCCP should be accurately verified in the design process. Full article
(This article belongs to the Topic Pipeline and Underground Space Technology)
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13 pages, 3189 KiB  
Article
A Simple and Effective Method for Measuring the Density of Non-Newtonian Thickened Tailings Slurry during Hydraulic Transport
Sensors 2022, 22(20), 7857; https://doi.org/10.3390/s22207857 - 16 Oct 2022
Viewed by 1306
Abstract
The extension of the Żelazny Most tailings store facility (TSF), which is the largest in Europe, requires the transport of large amounts of tailings, e.g., from the central area of the TSF reservoir to the new southern extension (SE). In order to use [...] Read more.
The extension of the Żelazny Most tailings store facility (TSF), which is the largest in Europe, requires the transport of large amounts of tailings, e.g., from the central area of the TSF reservoir to the new southern extension (SE). In order to use the mature fine tailings deposits located under the clarified water in the TSF reservoir, which were thickened in the process of natural sedimentation, it was decided to choose suction dredgers that collect tailings a few meters from under the water surface. The dredgers, which are most commonly used for the extraction of sand or gravel, showed the ability to pump fine flotation tailings slurry in the conducted tests. However, in order to reduce the costs of the entire operation, it was necessary to control the density of the slurry. The article presents a prototype installation for measuring the efficiency of the solid phase of the “in situ” dredging process in real time. The installation was designed for the needs of dredging a deposit of tailings that were thickened in the natural sedimentation process, and which had a particle size of below 63 μm. The installation consists of a flow meter, a densimeter, and a section for measuring the head loss of the flow of the slurry. The applied methodology allows for the current assessment of the dredger’s operating parameters, which translates into a more effective–in terms of process efficiency–management of the dredger’s work. Full article
(This article belongs to the Topic Pipeline and Underground Space Technology)
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17 pages, 5607 KiB  
Article
Methodology for the Prediction of Water Gushing in Tunnels in Igneous Fracture Tectonic Zones: A Case Study of a Tunnel in Guangdong Province, China
Appl. Sci. 2022, 12(20), 10438; https://doi.org/10.3390/app122010438 - 16 Oct 2022
Viewed by 1450
Abstract
The disaster of water gushing is very liable to occur when tunnels are built in the water-rich fracture structures in igneous rock areas. Different sources of water gushing result in different sizes of disaster. The safety of human life and property are in [...] Read more.
The disaster of water gushing is very liable to occur when tunnels are built in the water-rich fracture structures in igneous rock areas. Different sources of water gushing result in different sizes of disaster. The safety of human life and property are in danger. For the prediction of water gushing in tunnels, the fuzzy clustering method was used to determine the source of the water gushing in this paper. The problem of subjectivity in traditional identification methods was solved by this method. On the basis of the fuzzy clustering method, dynamically changing parameters of the effective radius of the water gushing were introduced and regressed with the dynamic monitoring data and the hydrogeological survey results in an improved method for predicting water gushing. Then, an improved method for predicting water gushing, considering the source, was proposed. A deep underground, extra-long tunnel under construction in the igneous region of southern China was used to verify the soundness of this improved method. Research results showed that the water gushing into the tunnel had a low correlation with surface water with a similarity index of λmin=0.3967 in the results of the second test. The water came mainly from within the rock mass. The effective radius were jointly determined by the average thickness of the rock aquifer and water gushing time, together with a positive correlation. The period of water gushing was divided into three stages. The predictions had a good accuracy rate with an error of 10% or less. These results could provide a reference and theoretical support for site construction. Full article
(This article belongs to the Topic Pipeline and Underground Space Technology)
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20 pages, 8924 KiB  
Article
Numerical Study of Influencing Factors of Safety and Stability of Tunnel Structure under Airport Runway
Appl. Sci. 2022, 12(20), 10432; https://doi.org/10.3390/app122010432 - 16 Oct 2022
Viewed by 1302
Abstract
A six-degree-of-freedom mathematical model and mechanical balance equation of a “five-point-contact” aircraft are established in this study. The model and equation are used to investigate the safety and stability of a tunnel structure under the runway of an airport, particularly when aircraft taxi [...] Read more.
A six-degree-of-freedom mathematical model and mechanical balance equation of a “five-point-contact” aircraft are established in this study. The model and equation are used to investigate the safety and stability of a tunnel structure under the runway of an airport, particularly when aircraft taxi or move on the runway. ABAQUS is used to construct a three-dimensional finite element model of the cooperative deformation of the airport runway–soil–tunnel structure. The analysis focuses on the response and evolution of structural safety mechanical indices from the perspective of three influencing factors: type of aircraft, road surface, and burial depth. The results show that the distribution position of the main landing gear wheel is more concentrated using the dynamic load equation of different aircraft. A rigid pavement is not easily deformed when subjected to aircraft loads, whereas a flexible pavement has an excellent attenuation effect on diffusing forces. The shear stresses on the upper and lower arches of the tunnel structure differ depending on the pavement material. The deformation of the arches under shear stress is more intense than that of other parts. With an increase in burial depth, the tunnel structure withstanding the aircraft load disturbance exhibits an attenuation trend. The disturbance caused by soil stress to the tunnel structure must not be ignored. When the burial depth of the tunnel exceeds 64 m, the tunnel structure ceases to be disturbed by aircraft loads. The research results can significantly guide airport construction and be used as a reference for investigating the safety and stability of substructures under airport runways. Full article
(This article belongs to the Topic Pipeline and Underground Space Technology)
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20 pages, 6360 KiB  
Article
Numerical Assessment of the Structural Damage of a Composite Lining Water Conveyance Tunnel Subjected to Reverse Fault Conditions
Buildings 2022, 12(10), 1647; https://doi.org/10.3390/buildings12101647 - 10 Oct 2022
Cited by 3 | Viewed by 1216
Abstract
In this paper, the structural responses and failure characteristics of a new type of water conveyance tunnel lining structure subjected to reverse fault conditions were numerically investigated by considering multiple loads and interaction separation modes between different structural layers. This study proposes a [...] Read more.
In this paper, the structural responses and failure characteristics of a new type of water conveyance tunnel lining structure subjected to reverse fault conditions were numerically investigated by considering multiple loads and interaction separation modes between different structural layers. This study proposes a new evaluation standard for the safety level of the damage state of the composite lining water conveyance tunnel. It also discusses the influences of fault dislocation displacement (Δf), dip angle (β), and the mechanical properties of the surrounding rock in the fault fracture zone on the water conveyance tunnel response and damage. The results indicate that the buckling failure of the steel tube under axial compression is the dominant failure mode of the composite lining structure. With increasing fault dislocation displacement, the axial compressive strain and circumferential shear strain of the composite lining are most severely damaged on the sliding plane. With decreasing fault dip angle, the axial compressive strain of the composite lining weakens, while the bending and shear strains increase. The increase in rock stiffness in the fault fracture zone reduces the damage scope but increases the composite lining structural damage severity. Overall, the numerical results of this study provide a better understanding of the failure mode and damage process of composite lining water conveyance tunnels under reverse fault conditions; therefore, this study can serve as a reference for composite lining structure disaster assessments. Full article
(This article belongs to the Topic Pipeline and Underground Space Technology)
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16 pages, 3358 KiB  
Article
Effect of Flocculants Residue on Rheological Properties of Ultra-Fine Argillaceous Backfilling Slurry
by , , , and
Materials 2022, 15(18), 6485; https://doi.org/10.3390/ma15186485 - 19 Sep 2022
Cited by 2 | Viewed by 1332
Abstract
Tailings concentration is indispensable for backfilling. Additionally, the residual flocculants in the concentration process affect the rheological properties of ultra-fine argillaceous backfilling slurry (e.g., viscosity and yield stress), resulting in a great effect on the fluidity and resistance of pipeline transportation. In this [...] Read more.
Tailings concentration is indispensable for backfilling. Additionally, the residual flocculants in the concentration process affect the rheological properties of ultra-fine argillaceous backfilling slurry (e.g., viscosity and yield stress), resulting in a great effect on the fluidity and resistance of pipeline transportation. In this study, to explore the effect of flocculants residue on the rheological properties of the slurry, a series of rheological tests (constant shear rate test and variable shear rate test) were performed by changing the type, dosage, stirring time, temperature of flocculants addition and the amount of binder added. The results showed that the addition of flocculants increased the viscosity and yield stress of slurry. At a certain amount of flocculants additive, the flocculant network structure reached the best development state, which had a positive effect on increasing slurry viscosity and yield stress. As the stirring time increased, the scale of damage to the flocculant network structure became larger, which had a negative effect on increasing slurry viscosity and yield stress. Low temperature weakened the adsorption and bridging effect of polymeric chains, resulting in a poorly developed flocculant network structure, which had a negative effect on increasing slurry viscosity and yield stress. Caused by hydration products, the viscosity and yield stress of slurry with binder further increased. This study is significant for an in-depth study of the rheological and pipeline transport characteristics of ultra-fine argillaceous backfilling slurry, optimising the selection of flocculants for ultrafine particles, guiding backfill parameters and improving the reliability of pipeline transport. Full article
(This article belongs to the Topic Pipeline and Underground Space Technology)
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16 pages, 7139 KiB  
Article
FEM-Based Analysis of the Loading Capacity of Defective Cable Tunnel Structures
Buildings 2022, 12(9), 1368; https://doi.org/10.3390/buildings12091368 - 02 Sep 2022
Viewed by 1309
Abstract
With the popularized application of underground cable tunnels in China, various structural defects such as cracking, deforming and material deteriorating also emerge. In cable tunnels that have been poorly maintained for a long time, there is always a coexistence of several kinds of [...] Read more.
With the popularized application of underground cable tunnels in China, various structural defects such as cracking, deforming and material deteriorating also emerge. In cable tunnels that have been poorly maintained for a long time, there is always a coexistence of several kinds of defects, and with the current methods of monitoring, it is difficult to identify the major defect affecting the load-carrying capacity and resolve it. However, the finite element method (FEM) can better solve this problem by analyzing the effect of a single defect parameter separately. In this paper, four different types of cable tunnels, namely the circular, rectangular, arched and trenched sectional tunnels, are modelled and analyzed with FEM. Defect parameters, including crack dimensions and concrete deterioration, are considered as variables, which are controlled and studied respectively. The results of the simulation indicate that the impact of crack propagation on the residual-bearing capacity of cable tunnels is much larger than that of concrete deterioration, especially the deepening of cracks. Works in this paper have the potential to be further referenced for cable-tunnel structure estimation and defect prevention. Full article
(This article belongs to the Topic Pipeline and Underground Space Technology)
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25 pages, 7764 KiB  
Article
Mechanical Responses of Slurry Shield Underpassing Existing Bridge Piles in Upper-Soft and Lower-Hard Composite Strata
Buildings 2022, 12(7), 1000; https://doi.org/10.3390/buildings12071000 - 13 Jul 2022
Cited by 3 | Viewed by 1146
Abstract
With the development of urban metro systems, shield tunnels that pass through existing bridge pile foundations have become an inevitable engineering problem. Therefore, ensuring the stability of the strata and existing bridge piles during tunnel construction is a common goal in engineering practice. [...] Read more.
With the development of urban metro systems, shield tunnels that pass through existing bridge pile foundations have become an inevitable engineering problem. Therefore, ensuring the stability of the strata and existing bridge piles during tunnel construction is a common goal in engineering practice. Currently, research on the mechanical responses of strata and existing piles under different conditions of upper-soft and lower-hard composite strata during shield tunneling has not been conducted extensively. This paper presents a numerical simulation of a shield tunnel passing through an existing bridge pile foundation in upper-soft and lower-hard composite strata. Subsequently, the surface subsidence and mechanical responses of a single pile were analyzed and evaluated. Additional stresses generated in the soil by existing bridge piles and the selection of grouting pressure were considered to optimize the driving pressure of the slurry shield. Allowable values were proposed to evaluate the construction disturbances caused by the tunnel excavation. The results show that the disturbance to the soil and existing piles is significantly influenced by the hard-rock height ratio, and the surface subsidence increases when the hard-rock height ratio decreases. The displacement and internal force of a single pile are significantly influenced by the load applied to the pile. This study demonstrates the changes in the mechanical responses of a single pile during shield tunnel boring, and provides in-depth insights into the deformation control caused by shield underpassing structures in upper-soft and lower-hard composite strata. Full article
(This article belongs to the Topic Pipeline and Underground Space Technology)
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13 pages, 5919 KiB  
Article
An Experimental Study of the Mechanical Properties of Partially Rehabilitated Cable Tunnels
Materials 2022, 15(14), 4830; https://doi.org/10.3390/ma15144830 - 11 Jul 2022
Viewed by 996
Abstract
For buried municipal tunnels—such as cable tunnels and utility tunnels with structural defects—due to the sheltering of the internal pipelines, shelves, and other auxiliary facilities, traditional trenchless rehabilitating methods are not applicable since an intact ring is needed for spraying and lining. In [...] Read more.
For buried municipal tunnels—such as cable tunnels and utility tunnels with structural defects—due to the sheltering of the internal pipelines, shelves, and other auxiliary facilities, traditional trenchless rehabilitating methods are not applicable since an intact ring is needed for spraying and lining. In these tunnels, only the exposed area at the crown of the ring can be partly rehabilitated. In this paper, three-edge bearing tests (TEBTs) for partially rehabilitated reinforced concrete (RC) pipe sections are carried out to simulate the case of a municipal tunnel and the effects of different repair materials (cement mortar and epoxy resin) and different dimensional parameters of the liner (lining thickness, lining range) on the partial rehabilitation effect of defective RC pipes are studied. The deforming compatibility of the liner–pipe interface is discussed, and the flexural rigidity of the partially rehabilitated section is calculated. The results show that the load-carrying capacities of partial rehabilitated RC pipes are effectively improved. Full article
(This article belongs to the Topic Pipeline and Underground Space Technology)
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21 pages, 5225 KiB  
Article
Genetic Algorithm-Based Intelligent Selection Method of Universal Shield Segment Assembly Points
Appl. Sci. 2022, 12(14), 6926; https://doi.org/10.3390/app12146926 - 08 Jul 2022
Cited by 2 | Viewed by 1166
Abstract
The proportion of universal segment in tunnel construction is constantly increasing. A key factor affecting the quality of tunnel construction is the selection of the shield segment assembly points. Nevertheless, the quality and efficiency of the current manual selection method cannot be guaranteed. [...] Read more.
The proportion of universal segment in tunnel construction is constantly increasing. A key factor affecting the quality of tunnel construction is the selection of the shield segment assembly points. Nevertheless, the quality and efficiency of the current manual selection method cannot be guaranteed. To realize a high correct rate, high efficiency and intelligence of universal segment assembly points selection, an intelligent selection method of assembly points is proposed. First, the objective function is established by considering the thrust cylinder stroke and shield tail gap differences. Second, to adaptively optimize the weights of the objective function, the working conditions are divided into 81 intervals, and a genetic algorithm is proposed to optimize weights in each interval. Third, a Monte-Carlo-based method is proposed to generate an example dataset, which is used for the genetic algorithm to optimize the weights. Finally, the proposed method was applied to the segment assembly points selection for Line 8 of the Zhengzhou rail transit in China. The results show that the method of assembly segment selection can reach a 90.6% correct rate in the field. The research results of this paper can be used for the selection of the universal shield segment assembly points. Full article
(This article belongs to the Topic Pipeline and Underground Space Technology)
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13 pages, 6751 KiB  
Article
Numerical Simulation on Backfilling of Buried Pipes Using Controlled Low Strength Materials
Appl. Sci. 2022, 12(14), 6901; https://doi.org/10.3390/app12146901 - 07 Jul 2022
Cited by 5 | Viewed by 1604
Abstract
The backfill quality of a pipeline has an important influence on pipeline operation. When loose backfill is used, the pipeline may be damaged after short term operation. In this study, the numerical simulation analysis of buried pipes was carried out under three conditions: [...] Read more.
The backfill quality of a pipeline has an important influence on pipeline operation. When loose backfill is used, the pipeline may be damaged after short term operation. In this study, the numerical simulation analysis of buried pipes was carried out under three conditions: loose backfill around the pipe, dense backfill, and controlled low strength materials (CLSM) backfill. The effects of narrow trench backfilling using CLSM on the force and deformation of pipelines were studied. The results showed that When CLSM was used for buried pipe backfilling, the pressure on the top of the pipe and on the side of the pipe was significantly reduced. When the surface pressure was 200 kPa, the radial displacement at the top of the pipe was only 0.6 mm. Compared with the dense backfill of the pipe, the radial displacement of the pipe top was reduced by 82.9%, which greatly reduced the deformation of the pipe. CLSM backfilling is a good way to protect the pipeline. The pressure is uniformly applied around the pipe, and the circumferential strain around the pipe is greatly reduced. Pipelines backfilling with CLSM for buried flexible pipes has good mechanical properties and it is expected to be applied to engineering practice. Full article
(This article belongs to the Topic Pipeline and Underground Space Technology)
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23 pages, 8398 KiB  
Article
Experimental and Numerical Investigation of Plastic–Concrete Waterproof Walls of an Underground Granary Subject to Combined Bending Moment and Water Pressure
Buildings 2022, 12(7), 893; https://doi.org/10.3390/buildings12070893 - 24 Jun 2022
Cited by 2 | Viewed by 1378
Abstract
To investigate the mechanical properties of plastic–concrete silo walls in practice, the mechanical properties and failure mechanism under the combined bending moment and water pressure were analyzed through the uniform loading test, water pressure test, and numerical analysis. The influence of the connecting [...] Read more.
To investigate the mechanical properties of plastic–concrete silo walls in practice, the mechanical properties and failure mechanism under the combined bending moment and water pressure were analyzed through the uniform loading test, water pressure test, and numerical analysis. The influence of the connecting plate spacing, radius, and the waterproof plate thickness on the water pressure-bearing capacity were analyzed. The test results show that the chemical adhesive force exists between the waterproof plate and concrete and can resist 20 kPa. The displacement and strain of the waterproof plate increases significantly with the increment in water pressure. When the water pressure reached 85 kPa, the specimen was damaged due to shear failure. The established numerical model was validated by the test results. The numerical analysis results show that the specimen failure mainly depends on the bolt strength when the thickness of the waterproof plate is greater than 14 mm or the radius of the connecting plate is greater than 60 mm. The relation between the design parameters and the water pressure-bearing capacity was proposed. Compared with the waterproof plate thickness, the connecting plate spacing and radius have greater influence on the water pressure-bearing capacity. Full article
(This article belongs to the Topic Pipeline and Underground Space Technology)
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15 pages, 85448 KiB  
Article
Study on Spraying Construction Method of a Non-Water Reacting Polymer Layer in the Tunnel
Materials 2022, 15(12), 4138; https://doi.org/10.3390/ma15124138 - 10 Jun 2022
Cited by 3 | Viewed by 1361
Abstract
Non-water reacting double-component foamed polyurethane has been increasingly used in the field of transportation. Particularly, it is recognized that a polymer damping layer between tunnel linings and surrounding rocks can improve the seismic performance of tunnels. To facilitate the application of this polymer [...] Read more.
Non-water reacting double-component foamed polyurethane has been increasingly used in the field of transportation. Particularly, it is recognized that a polymer damping layer between tunnel linings and surrounding rocks can improve the seismic performance of tunnels. To facilitate the application of this polymer in tunnels, a spraying construction method of polymer damping layers was proposed. The polymer damping layer was prepared with hydraulic spraying equipment, and the construction process included the pre-treatment of the tunnel base surface, the pressure control of the spraying equipment, the adjustment of the spray gun working parameters and spraying quality control. In this paper, the effects of material ratio, material temperature, environmental factors (i.e., temperature, humidity and wind speed), spraying pressure and spray gun parameters (i.e., speed, distance from the sprayed surface and spray angle) on the layer formation were investigated. Thus, spraying parameters for better spraying performance were recommended. This study will provide technical support for polymer damping layer construction in the seismic design of tunnels. Full article
(This article belongs to the Topic Pipeline and Underground Space Technology)
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26 pages, 10252 KiB  
Article
Analysis of the Interaction Effects of Shield Structure Oblique Passing under an Existing Tunnel
Appl. Sci. 2022, 12(11), 5569; https://doi.org/10.3390/app12115569 - 30 May 2022
Cited by 2 | Viewed by 1536
Abstract
The interaction mechanism between a two-lane shield tunnel and an existing tunnel during oblique underpass is a matter of widespread concern in the engineering community, and knowledge in this area remains crude. In the construction of subway tunnels in mountainous cities with huge [...] Read more.
The interaction mechanism between a two-lane shield tunnel and an existing tunnel during oblique underpass is a matter of widespread concern in the engineering community, and knowledge in this area remains crude. In the construction of subway tunnels in mountainous cities with huge topographical fluctuations, internal forces and deformations are inevitable in existing tunnels. To verify the applicability of existing shield construction technology and empirical parameters to the Guiyang area, a systematic and refined numerical analysis was conducted on the shield passing under the existing tunnel section of the Tao-Hua interval of Guiyang Metro Line 3. In this paper, the accuracy of the numerical simulation is verified by comparing the calculated results with the data measured in the field; the settlement pattern that appeared above the existing tunnel during the construction of the shield with slurry hardening is analyzed; the internal forces, lateral deformation, and torsional deformation of the existing tunnel caused during the excavation of the new tunnel are obtained based on the numerical simulation results; finally, the effect of the old and new tunnels on the torsional deformation and settlement of the existing tunnel under different spatial intersection angles is studied. The results show that the internal forces, lateral deformation, and surface settlement of the existing tunnel due to the diagonal underpass show obvious asymmetric characteristics. Additionally, the existing tunnel experiences local irrecoverable torsional deformation, with the maximum torsional deformation occurring at the intersection of the old and new tunnels, and the spatial intersection angle of the old and new tunnels has a great influence on the maximum settlement of the tunnel vault and arch bottom, which shows a negative correlation. Full article
(This article belongs to the Topic Pipeline and Underground Space Technology)
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21 pages, 8853 KiB  
Article
Modeling GPR Wave Propagation in Complex Underground Structures Using Conformal ADI-FDTD Algorithm
Appl. Sci. 2022, 12(10), 5219; https://doi.org/10.3390/app12105219 - 21 May 2022
Cited by 5 | Viewed by 1233
Abstract
Ground Penetrating Radar (GPR) is a shallow geophysical method for detecting and locating subsurface targets. The GPR image echo characteristics of complex underground structures can be obtained by carrying out GPR forward modeling research. The traditional finite-difference time-domain (FDTD) method has low efficiency [...] Read more.
Ground Penetrating Radar (GPR) is a shallow geophysical method for detecting and locating subsurface targets. The GPR image echo characteristics of complex underground structures can be obtained by carrying out GPR forward modeling research. The traditional finite-difference time-domain (FDTD) method has low efficiency and accuracy. The alternating direction implicit FDTD (ADI-FDTD) algorithm surmounts the stability limitations of the traditional FDTD method, making it possible to select a larger time step for higher computational efficiency. For circular underground structures, a pseudowave produced by the ladder approximation method can be corrected using the surface conformal technique. This paper proposes a high-efficiency and high-accuracy GPR forward modeling method that combines the ADI-FDTD algorithm and surface conformal technology. The performance of the conformal ADI-FDTD algorithm is verified by a simple two-layer model. Based on the proposed algorithm, the GPR image features of three complex underground structure models are obtained. Finally, a field experiment is used to support the accuracy and usefulness of the conformal ADI-FDTD algorithm. The numerical simulation results and experimental results show that the conformal ADI-FDTD algorithm reduces the pseudodiffraction wave caused by the ladder approximation method and can significantly improve the computing efficiency for complex underground structure models. Full article
(This article belongs to the Topic Pipeline and Underground Space Technology)
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16 pages, 3887 KiB  
Article
Resistance Loss in Cemented Paste Backfill Pipelines: Effect of Inlet Velocity, Particle Mass Concentration, and Particle Size
Materials 2022, 15(9), 3339; https://doi.org/10.3390/ma15093339 - 06 May 2022
Cited by 10 | Viewed by 1543
Abstract
Cemented paste backfill (CPB), a technology placing the solid waste into mined-out stopes in the mine through pipeline transportation, has been widespread all over the world. The resistance loss is an important parameter for pipeline transport, which is significantly affected by the slurry [...] Read more.
Cemented paste backfill (CPB), a technology placing the solid waste into mined-out stopes in the mine through pipeline transportation, has been widespread all over the world. The resistance loss is an important parameter for pipeline transport, which is significantly affected by the slurry characteristics. However, the coupling effect of inlet velocity (IV), particle mass concentration (PMC), and particle size (PS) has not been well evaluated and diagnosed. Hence, the CFD-based three-dimensional network simulation of CPB slurry flow in an L-shaped pipe at different combinations of the three parameters was developed using COMSOL Multiphysics software, and the findings were validated through a loop experiment. The results show that increasing IV and reducing PS will contribute to the homogeneity of the slurry in the pipeline, while the PMC presents little effect. The pipe resistance loss is positively correlated with IV and PMC and negatively correlated with PS. The sensitivity to the three parameters is IV > PS > PMC. In particular, the resistance loss is minimal at IV of 1.5 m/s, PMC of 72%, and PS of 1000 um. The calculation model of resistance loss regressed from simulation presented a high accuracy with an error of 8.1% compared with the test results. The findings would be important for the design of the CPB pipeline transportation and provide guidance in the selection of transfer slurry pumps, prepreparation of backfill slurry, and pipe blockage, which will improve the safety and economic level of a mine. Full article
(This article belongs to the Topic Pipeline and Underground Space Technology)
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20 pages, 1261 KiB  
Article
Research on an Evaluation Method for the Adaptability of TBM Tunnelling
Appl. Sci. 2022, 12(9), 4590; https://doi.org/10.3390/app12094590 - 30 Apr 2022
Cited by 4 | Viewed by 1316
Abstract
When a TBM carries out tunnelling in complex strata, there is often low tunnelling efficiency and an increase in tunnelling costs due to the improper selection of tunnelling parameters, the wrong estimation of geological conditions, or adverse geology, so it is necessary to [...] Read more.
When a TBM carries out tunnelling in complex strata, there is often low tunnelling efficiency and an increase in tunnelling costs due to the improper selection of tunnelling parameters, the wrong estimation of geological conditions, or adverse geology, so it is necessary to evaluate the tunnelling adaptability of TBM construction. In this paper, based on hydraulic engineering in Xinjiang, 11 evaluation indexes of TBM tunnelling adaptability are determined by comprehensively considering the influence of tunnelling parameters, geological conditions, and adverse geological factors on TBM tunnelling adaptability. After that, the membership function of each evaluation index is determined by referring to the existing research results and fuzzy mathematics method, and the weight of each evaluation index is determined and adjusted by the analytic hierarchy process (AHP)–entropy weight (EW) method. Finally, the adaptability evaluation method and evaluation model of TBM tunnelling are put forward. The TBM tunnelling adaptability evaluation model proposed in this paper is verified by relying on the actual situation of three interval tunnels in the project, and good effects are obtained. This study can provide a reference for the evaluation of TBM tunnelling adaptability in similar strata. Full article
(This article belongs to the Topic Pipeline and Underground Space Technology)
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14 pages, 4097 KiB  
Article
Experimental Study on the Mix Proportion and Mechanical Properties of New Underwater Cementitious Filling Materials
Materials 2022, 15(8), 2938; https://doi.org/10.3390/ma15082938 - 18 Apr 2022
Cited by 1 | Viewed by 1628
Abstract
Considering that it is difficult for traditional materials to simultaneously meet the requirements for filling grouting of water-filled karst caves and subsequent shield tunneling, an environmentally friendly and controllable new underwater cementitious filling material (NUC-FM) is developed, with abandoned shield mud as the [...] Read more.
Considering that it is difficult for traditional materials to simultaneously meet the requirements for filling grouting of water-filled karst caves and subsequent shield tunneling, an environmentally friendly and controllable new underwater cementitious filling material (NUC-FM) is developed, with abandoned shield mud as the basic raw material. Through laboratory tests, the mechanical property parameters of NUC-FM are tested, and its micromechanism is analyzed. The research results show that there is excellent synergistic interactions among shield mud, cement, flocculant, fly ash and other raw materials. The NUC-FM grouting filling material with superior performance can be prepared when the water binder ratio is between 0.45 and 0.6 and the water consumption is between 270 and 310 kg/m3. It has the characteristics of non-dispersion underwater and moderate consolidated body strength. The compressive strength of the NUC-FM consolidated body samples under each mix proportion is much higher than 0.5 MPa, which meets the technical strength requirements of a construction site, and the microstructure shows that there is an obvious dense and stable block structure inside. The cost of the NUC-FM prepared with an optimized mix proportion is only 34.57 dollars/m3, which is far lower than the market purchase price of concrete and cement mortar. It can be predicted that the NUC-FM is an ideal filling grouting material for water-filled karst caves in shield tunnels in water-rich karst areas. Full article
(This article belongs to the Topic Pipeline and Underground Space Technology)
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