Research

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25 pages, 18470 KiB

Open AccessArticle

Research on Excavation Method for Soft Rock Tunnel Based on Stress Release Rate

by Jincheng Nie, Chuan He, Hao Kou, Fuhua Liu and Wenbo Yang

Appl. Sci. 2024, 14(2), 668; https://doi.org/10.3390/app14020668 - 12 Jan 2024

Viewed by 614

A test method for controlling the stress release rate of the tunnel by adjusting the confining pressure is proposed based on the engineering background of Dongmachang No. 1 Tunnel of Huali Expressway to explore a suitable excavation method of soft rock tunnel. Based [...] Read more.

A test method for controlling the stress release rate of the tunnel by adjusting the confining pressure is proposed based on the engineering background of Dongmachang No. 1 Tunnel of Huali Expressway to explore a suitable excavation method of soft rock tunnel. Based on the relationship between stress release rate, displacement release rate, and longitudinal advance of excavation face, the model test of tunnel excavation is carried out. On this basis, combined with the horizontal loading test and field monitoring results, the influence of three excavation methods, the three-bench method, three-bench with reserved core soil method, and three-bench seven-step method, on the mechanical behavior of the tunnel is studied. The research shows that the load shared by the double-layer initial support is not equal, and the second-layer initial support only bears 20% of the pressure of the first-layer initial support; replacing the three-bench method with the three-bench core soil method and the three-bench seven-step method can reduce the deformation of the surrounding rock by 8.7~12.4%, and the load borne by the supporting structure is transferred from the second layer to the first layer. In order to take into account the safety and efficiency of tunnel construction, it is recommended to use the three-bench core soil method for excavation. The research results can provide a theoretical reference for the construction of related tunnel projects. Full article

(This article belongs to the Special Issue Advances in Tunneling and Underground Engineering)

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15 pages, 8006 KiB

Open AccessArticle

The Law and Mechanism of the Effect of Surface Roughness on Microwave-Assisted Rock Breaking

by Fangfang Chen, Guoqing Li, Zhiqiang Zhang and Zhanqiang Wu

Appl. Sci. 2024, 14(1), 207; https://doi.org/10.3390/app14010207 - 26 Dec 2023

Viewed by 655

Abstract

In physical engineering, a rock surface, whether naturally or artificially formed, is rough. When irradiating rocks, microwaves produce reflections and diffractions on the surface of rough rocks, which significantly affect the absorption of microwave energy by rocks, thus influencing the result of microwave [...] Read more.

In physical engineering, a rock surface, whether naturally or artificially formed, is rough. When irradiating rocks, microwaves produce reflections and diffractions on the surface of rough rocks, which significantly affect the absorption of microwave energy by rocks, thus influencing the result of microwave irradiation. In order to explore the influence of rough rock surfaces on the effect of microwave-assisted rock breaking, microwave irradiation tests were carried out on basalt samples with different values of roughness to test the temperature and P-wave velocity of the samples before and after microwave irradiation. Numerical test methods were used to systematically study the influence of rough rock surfaces on microwave irradiation. The results show that, under the same microwave irradiation conditions, the effect of microwave irradiation on rough surface basalt is more significant than that of flat surface basalt. The surface temperature distribution range of flat surface specimens is narrow, the surface temperature range of rough surface specimens is wider and more inhomogeneous, and the maximum surface temperatures of rough surface specimens are much higher than those of flat surface specimens. After irradiation, new macroscopic cracks were generated on the surface of the samples, and the crack propagation of the rough surface samples was more obvious. The decrease in P-wave velocity before and after the irradiation of flat surface samples is small, and that of rough surface samples is larger. The main factors affecting the effect of microwave irradiation on the rough surface are the refraction and reflection of electromagnetic waves, heat conduction, and stress concentration on the surface. Full article

(This article belongs to the Special Issue Advances in Tunneling and Underground Engineering)

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27 pages, 12154 KiB

Open AccessArticle

Experimental Study on a Granular Material-Filled Lining in a High Ground-Stress Soft-Rock Tunnel

by Jie Liu, Bin Wang, Yansong Wang, Lei Shi, Xiaokang Xie and Jun Lan

Appl. Sci. 2023, 13(24), 13326; https://doi.org/10.3390/app132413326 - 17 Dec 2023

Viewed by 804

Abstract

For high ground-stress soft-rock tunnels surrounding rock with large deformation, rapid deformation rate, a long creep time, and a high likelihood of to causing initial and secondary lining damage, the yielding and relief-pressure support technology of a lining filled with a granular material [...] Read more.

For high ground-stress soft-rock tunnels surrounding rock with large deformation, rapid deformation rate, a long creep time, and a high likelihood of to causing initial and secondary lining damage, the yielding and relief-pressure support technology of a lining filled with a granular material is proposed. A layer of granular material is placed at the reserved deformation layer of the tunnel to provide the surrounding rock with a certain amount of deformation space. Confined compression tests were undertaken to study the laws of compressive strain, load reduction law, and horizontal force variation of different granular materials under different rock stresses. The research showed that the compressibility and load reduction performance of 8 mm soil was optimal. Its maximum compressive strain reached 47.6%, and the total load reduction rate reached 71%. The yielding- and relief-pressure effects of the granular sand-filled lining support were analyzed from the angles of deflection, pressure, and energy. The results show that the highest reduction rate of deflection was 36.7%, and the greatest load reduction rate of pressure was 78%. The grainy filling material can remove part of the load imposed by the surrounding rock on the support structure of the secondary lining through yielding pressure and relief pressure, which dramatically reduces the damage to the secondary lining from the surrounding rock. The research results have specific reference significance for designing and constructing tunnel support structures. Full article

(This article belongs to the Special Issue Advances in Tunneling and Underground Engineering)

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15 pages, 5241 KiB

Open AccessArticle

Safety Evaluation of Crossing Tunnel Engineering: A Case Study

by Dai Xianyao, Wang Guobin, Ye Ming and Zhang Yongquan

Appl. Sci. 2023, 13(16), 9459; https://doi.org/10.3390/app13169459 - 21 Aug 2023

Viewed by 839

Abstract

With the growing demand for transportation, there has been a significant increase in road-related projects, leading to potential risks in the safety of existing structures. This paper presents a study on the influence of new tunnel construction on the stability of an adjacent [...] Read more.

With the growing demand for transportation, there has been a significant increase in road-related projects, leading to potential risks in the safety of existing structures. This paper presents a study on the influence of new tunnel construction on the stability of an adjacent existing tunnel and provides valuable insights for the safety technology evaluation of similar tunnel crossing projects. In order to evaluate the influence of tunnel excavation on adjacent tunnels, the excavation process of a new tunnel near the original tunnel is simulated using the finite element software Midas GTS. This analysis includes the evaluation of static and dynamic responses. The results indicate that the horizontal and vertical displacements caused by the excavation of the railway tunnel are minimal. Furthermore, during the blasting excavation of the railway tunnel, the vibration velocity experienced by the highway tunnel remains below the safe allowable limit. These findings demonstrate that in this project, the influence of blasting excavation for the railway tunnel on the highway tunnel is both safe and manageable. Full article

(This article belongs to the Special Issue Advances in Tunneling and Underground Engineering)

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20 pages, 20969 KiB

Open AccessArticle

Influence of Spherical Caverns on the Failure Characteristics of Neighboring Tunnels under True Triaxial Conditions: Insights from an Experimental Test and Discrete Element Simulation

by Congcong Chen, Xianwei She and Yusong Zhao

Appl. Sci. 2023, 13(13), 7688; https://doi.org/10.3390/app13137688 - 29 Jun 2023

Viewed by 728

Abstract

Caverns are generally formed by a combination of regional geological action and groundwater, and their improper treatment will inevitably lead to dangerous conditions in underground works. To detect the specific failure mechanism of tunnel-surrounding rock induced by invisible caverns, a true triaxial compression [...] Read more.

Caverns are generally formed by a combination of regional geological action and groundwater, and their improper treatment will inevitably lead to dangerous conditions in underground works. To detect the specific failure mechanism of tunnel-surrounding rock induced by invisible caverns, a true triaxial compression test is conducted, accompanied by acoustic emission technology and an internal borehole camera, for monitoring the acoustic response and visible secondary cracks, and a corresponding DEM simulation is carried out to reveal the meso-mechanism. The results indicate the following: (1) The invisible cavern demonstrates a negative influence on the stability of the tunnel and leads to a 25.82% reduction in the peak z-axis load of the specimens. (2) The acoustic emission results show that the relatively severe dominant failures mainly occur near the peak stress in all types of specimens, and the speed and intensity of the cavern-existing specimen is significantly greater than that of the cavern-free specimen. (3) The cavity-free tunnel shows mirror-symmetric splitting failure on the left and right sidewalls, while the secondary cracks appear earlier and show asymmetrical distribution in the cavern-existing specimen, and the volume of broken rock blocks near the free surface is larger. (4) The cavern directly changes the failure process of the tunnel-surrounding rock (intermediate rock failure occurs earlier than splitting failure), the distribution of principal stress, and the corresponding mechanism of secondary failures. (5) Application of the displacement and velocity trend fields helped to reveal accurate failure procedures in the true triaxial test. Full article

(This article belongs to the Special Issue Advances in Tunneling and Underground Engineering)

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22 pages, 16961 KiB

Open AccessArticle

Theoretical Approach to Predicting the Diffusion Radius of Fracture Grouting in Soil–Rock Mixtures

by Zuliang Zhong, Jiayong Li and Congying Bie

Appl. Sci. 2023, 13(8), 4730; https://doi.org/10.3390/app13084730 - 09 Apr 2023

Cited by 1 | Viewed by 1283

Abstract

Previously conducted studies have established that the soil–rock mixture in the Chongqing area has the characteristics of loose structure, poor stability, strong permeability, and so on. When building a tunnel in a soil–rock mixture stratum, it is necessary to reinforce the surface rock [...] Read more.

Previously conducted studies have established that the soil–rock mixture in the Chongqing area has the characteristics of loose structure, poor stability, strong permeability, and so on. When building a tunnel in a soil–rock mixture stratum, it is necessary to reinforce the surface rock mass and surrounding rock by grouting to improve the safety of tunnel excavation. To study the diffusion mechanism of cement slurry (Bingham fluid) in soil–rock mixtures, based on the Bingham fluid flow equation and slurry diffusion model, the Bingham fluid fracture diffusion formula was derived, and field grouting tests and indoor model tests were carried out with soil–rock mixtures in the Chongqing area as the research object. The fracture grouting diffusion formula was verified and analyzed using the test data. The research results show that the theoretical calculation results of various working conditions are close to the actual test results (the error of indoor model test results is less than 3%, and the error of field test results is less than 5%). A Bingham fluid fracture diffusion formula has been developed that applies to various working conditions of fracture grouting of soil–rock mixtures and has a good prediction effect on the value of the fracture diffusion radius. Full article

(This article belongs to the Special Issue Advances in Tunneling and Underground Engineering)

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24 pages, 11138 KiB

Open AccessArticle

Analytical Prediction of Tunnel Deformation Beneath an Inclined Plane: Complex Potential Analysis

by Pieride Mabe Fogang, Yang Liu, Jia-Le Zhao, Thierno Aliou Ka and Shuo Xu

Appl. Sci. 2023, 13(5), 3252; https://doi.org/10.3390/app13053252 - 03 Mar 2023

Cited by 2 | Viewed by 1288

Abstract

When excavating a tunnel, the stresses are distributed asymmetrically along the tunnel cross-section. Other factors, particularly slope friction force and excavation speed, can also contribute to the deformation and displacement of a tunnel. Despite this, several authors have used the complex potential method [...] Read more.

When excavating a tunnel, the stresses are distributed asymmetrically along the tunnel cross-section. Other factors, particularly slope friction force and excavation speed, can also contribute to the deformation and displacement of a tunnel. Despite this, several authors have used the complex potential method to predict the ground deformation surrounding the tunnel. However, their applicability to the ground response caused by the asymmetric stress distribution around the tunnel wall is analysed in this context. This paper, therefore, proposes an approximate solution on the slope to predict the tunnel cross-section deformation. The solution is based on the complex potential method to predict analytically and numerically the ground deformation around the tunnel. However, two variables called the “complex potential functions” for the Laurent series expansion are used for the stress redistribution to the tunnel boundary conditions. Data from the Qijiazhuang tunnel case are used to justify the proposed analytical solutions. This solution is an essential guide for analyzing deformations in complex geological conditions and structures, such as steeper slopes. Full article

(This article belongs to the Special Issue Advances in Tunneling and Underground Engineering)

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10 pages, 1303 KiB

Open AccessArticle

Experimental Study on Interface Frictional Characteristics between Sand and Steel Pipe Jacking

by Zhe Mei, Anfeng Xiao, Jiahao Mei, Jinqiu Hu and Peng Zhang

Appl. Sci. 2023, 13(3), 2016; https://doi.org/10.3390/app13032016 - 03 Feb 2023

Cited by 3 | Viewed by 1276

Abstract

In order to study the variation law of shear frictional characteristics of the steel pipe jacking and sand interface under different working conditions, the shear stress–strain curve between five different particle sizes of sand and steel pipe jacking under different normal stress and [...] Read more.

In order to study the variation law of shear frictional characteristics of the steel pipe jacking and sand interface under different working conditions, the shear stress–strain curve between five different particle sizes of sand and steel pipe jacking under different normal stress and slurry lubrication conditions was measured by using a direct shear device, and the internal friction angle, friction coefficient and cohesion of the pipe–soil interface were calculated by regression analysis. The test results show that the shear stress between sand and steel pipe jacking decreases with the increase of the average particle size of the sand, and the strain-softening phenomenon occurs. The normal stress does not change the trend of the shear stress–strain curve at the pipe–soil interface, and the peak and residual values of the shear stress increase with the increase of the normal stress. The peak and residual values of the shear stress at the pipe–soil interface under the slurry lubrication condition are smaller than those under the no slurry lubrication condition. The peak shear stress between the pipe and soil under the lubricated slurry condition decreases by about 20%. The internal friction angle and friction coefficient of the pipe–soil interface decrease with the increase of the particle size, and there is no obvious pattern between the cohesion quantity relationship and the average particle size. Full article

(This article belongs to the Special Issue Advances in Tunneling and Underground Engineering)

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11 pages, 5457 KiB

Open AccessCommunication

Effect of the Umbrella Arch Technique Modelled as a Homogenized Area above a Cross Passage

by Ibtissem Siad, Mustapha Akchiche and Panagiotis Spyridis

Appl. Sci. 2023, 13(3), 1588; https://doi.org/10.3390/app13031588 - 26 Jan 2023

Viewed by 850

Abstract

The stability of tunnel cross passages excavated in soft soil has always been a major challenge. In recent years, new techniques based on the installation of pre-reinforcements before tunnel excavation have been developed to control excavation-induced deformation and surface settlements. In this paper, [...] Read more.

The stability of tunnel cross passages excavated in soft soil has always been a major challenge. In recent years, new techniques based on the installation of pre-reinforcements before tunnel excavation have been developed to control excavation-induced deformation and surface settlements. In this paper, a finite element numerical simulation was conducted to study the reduction effect of an umbrella vault element modelled as a homogenized area on the deformations induced after the excavation of a cross passage. The results of this study show that the ground deformations can be controlled efficiently by using this type of pre-reinforcement. However, the findings showed that there is no effect of the umbrella arch length on the reduction of the ground deformations. This paper represents a very good demonstration of 3D modelling of tunnel junctions using pre-support techniques; it is the most advanced/appropriate research tool for studying the behaviour of cross passages and is useful as a paradigm for other researchers and practitioners. Full article

(This article belongs to the Special Issue Advances in Tunneling and Underground Engineering)

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17 pages, 6144 KiB

Open AccessArticle

Ground-Borne Vibration Model in the near Field of Tunnel Blasting

by Yufan Gao, Hongxian Fu, Xing Rong and Gustavo Paneiro

Appl. Sci. 2023, 13(1), 87; https://doi.org/10.3390/app13010087 - 21 Dec 2022

Cited by 2 | Viewed by 1227

Abstract

Accurate prediction of blasting vibration associated with tunnel engineering is essential to ensure the safety and stability of tunnel excavation and to prevent any damage or distress to adjacent existing tunnels. Based on the dimensional analysis principle, this paper deduces the classical Sadovsky [...] Read more.

Accurate prediction of blasting vibration associated with tunnel engineering is essential to ensure the safety and stability of tunnel excavation and to prevent any damage or distress to adjacent existing tunnels. Based on the dimensional analysis principle, this paper deduces the classical Sadovsky formula, analyzes its limitations from a mathematical point of view, and proves the feasibility of using this principle to derive a prediction model of blasting vibration. On this basis, considering the influence factors of blasting vibration such as the rock density, delay initiation time, and number of free surfaces, a new prediction model that can simultaneously consider the influence of the vibration in near-field and far-field blasting is proposed, and its rationality is explained. Combined with a case study, comparative analysis, variance analysis, and Akaike information criterion, the results show that the new prediction model can effectively solve the difference in blasting vibration in different types of blast holes and different areas, and the calculated results are in better agreement with the monitoring data than is the Sadovsky formula. Overall, this study provides a new solution and reference for more accurate prediction of blasting vibration. Full article

(This article belongs to the Special Issue Advances in Tunneling and Underground Engineering)

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22 pages, 6278 KiB

Open AccessArticle

Research on Horizontal Directional Drilling (HDD) Trajectory Design and Optimization Using Improved Radial Movement Optimization

by Liangxing Jin and Junjie Wei

Appl. Sci. 2022, 12(23), 12207; https://doi.org/10.3390/app122312207 - 29 Nov 2022

Cited by 1 | Viewed by 2415

Abstract

In practice, the drilling path of horizontal directional drilling (HDD) projects is usually constructed by trial and error based on a preliminary designing trajectory. This study aimed to propose and test a method to predesign and optimize the drilling paths automatically, with the [...] Read more.

In practice, the drilling path of horizontal directional drilling (HDD) projects is usually constructed by trial and error based on a preliminary designing trajectory. This study aimed to propose and test a method to predesign and optimize the drilling paths automatically, with the view of improving the efficiency of HDD design preparations. Alternating straight and curvilinear segments is a commonly used method for designing drilling paths, especially the “straight—curvilinear—horizontal straight—curvilinear—straight” five-segment arrangement. The catenary method was proposed to design the drilling path with the advantage of lower friction for the mechanical constraints. However, it is difficult to be implemented with technology limitations due to its continuously changing curvature. In this study, five-segment trajectories were combined with the catenary trajectory to utilize their advantages using the improved radial movement optimization (IRMO) algorithm. Drilling mud pressure was considered in the processes of the mechanical design to avoid collapse or possible instability. Two different examples were tested in different scenarios, theoretical and practical. The results show that the IRMO algorithm has a great potential for automatically designing and optimizing preliminary drilling paths with low time-consumption and high feasibility. Full article

(This article belongs to the Special Issue Advances in Tunneling and Underground Engineering)

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Review

Jump to: Research

26 pages, 5570 KiB

Open AccessReview

Inversion Analysis Method for Tunnel and Underground Space Engineering: A Short Review

by Zhanping Song, Zifan Yang, Runke Huo and Yuwei Zhang

Appl. Sci. 2023, 13(9), 5454; https://doi.org/10.3390/app13095454 - 27 Apr 2023

Cited by 9 | Viewed by 2011

Abstract

With the rise of the fourth industrial revolution, traditional methods of analyzing investment have been transformed into intelligent methods under big data and the Internet of Things. This has created a new approach to solving practical engineering problems. This paper examines the formation [...] Read more.

With the rise of the fourth industrial revolution, traditional methods of analyzing investment have been transformed into intelligent methods under big data and the Internet of Things. This has created a new approach to solving practical engineering problems. This paper examines the formation and evolution of the application of inversion theory in tunnel and underground engineering, summarizing research progress using traditional and intelligent inversion analysis methods to identify three types of target unknown quantities in tunnels and underground projects: initial ground stress, support structure load, and tunnel characteristic parameters. It also offers an outlook on how to optimize inversion analysis methods to solve more challenging and complex tunneling problems in the context of informatization, digitalization, and intelligence. In the current research process of tunnel and underground space engineering problems, the inversion theory system has been improved, but inversion analysis methods still face many challenges. These include the low reliability of initial ground stress inversion under complex geological conditions, the lack of indicators to objectively evaluate the accuracy of inversion analysis, and the high costs of intelligent inversion analysis means. Moving forward in the context of big data and the information era, the future development direction for inversion theory and inversion methods in tunnel and underground space engineering is to combine new monitoring technology, computer vision technology, and simulation analysis technology to establish multifaceted intelligent inversion analysis models. Full article

(This article belongs to the Special Issue Advances in Tunneling and Underground Engineering)

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