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Sensors and Measurements in Geotechnical Engineering

A special issue of Sensors (ISSN 1424-8220). This special issue belongs to the section "Physical Sensors".

Deadline for manuscript submissions: closed (15 April 2022) | Viewed by 58186

Special Issue Editors


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Guest Editor
Faculty of Civil Engineering, Wroclaw University of Science and Technology, 50-370 Wroclaw, Poland
Interests: geotechnical engineering; civil engineering; piles foundation; deep excavations; soil improvement technologies; reuse of waste material; sustainable geotechnics
Special Issues, Collections and Topics in MDPI journals

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Guest Editor
Department of Geotechnics, University of Zilina, Univerzitna 8215/1, 010 26 Zilina, Slovakia
Interests: FBG sensors; MEMS based inclinometer; axial strain of geogrid; tensile force of geogrid; geogrid strain measurement, optical sensors; physical model; piled embankment
Special Issues, Collections and Topics in MDPI journals

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Guest Editor
Department of Engineering and Architecture, Università degli Studi di Parma, Parco Area delle Scienze, 43121 Parma, Italy
Interests: early warning systems; geotechnical monitoring; tunnel deformation and stresses; rock mechanics; artificial Intelligence; data mining and analysis; data calibration and validation
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Every civil engineering structure must have an individually designed foundation. The role of the geological and geotechnical survey is crucial in proper geotechnical design. The latest trends in geotechnical design methods emphasize the role of testing (number of performed tests, the possibility of active design based on observational method). Measurements of foundation capacity, settlement and displacements, and their quality control are vital aspects in course of construction. When it comes to ground and rock parameters, their values are very variable and may change in time due to construction stages. Many civil engineering structures must be monitored throughout their lifetime. Structural health monitoring systems are based on sensors and instrumentation for the postprocessing of gathered results.

The development of large infrastructural projects brings the need for fast and reliable testing methods and cost-effective devices for their control. This Special Issue is addressed to recent developments of all types of sensors, instruments, and measurement methods designed and developed for geotechnical testing and monitoring in civil engineering, environmental, and mining industry.

Dr. Jaroslaw Rybak
Prof. Marian Drusa
Prof. Dr. Andrea Segalini
Guest Editors

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Keywords

  • geotechnical survey
  • ground and rock parameters
  • foundation settlements
  • retaining wall displacements
  • slope stability monitoring
  • ground water control
  • quality control of earthworks

Published Papers (20 papers)

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25 pages, 15932 KiB  
Article
Photogrammetric Method to Determine Physical Aperture and Roughness of a Rock Fracture
by Masoud Torkan, Mateusz Janiszewski, Lauri Uotinen, Alireza Baghbanan and Mikael Rinne
Sensors 2022, 22(11), 4165; https://doi.org/10.3390/s22114165 - 30 May 2022
Cited by 9 | Viewed by 2414
Abstract
Rock discontinuities play an important role in the behavior of rock masses and have a high impact on their mechanical and hydrological properties, such as strength and permeability. The surfaces roughness and physical aperture of rock joints are vital characteristics in joint shear [...] Read more.
Rock discontinuities play an important role in the behavior of rock masses and have a high impact on their mechanical and hydrological properties, such as strength and permeability. The surfaces roughness and physical aperture of rock joints are vital characteristics in joint shear strength and fluid flow properties. This study presents a method to digitally measure the physical aperture of a rock fracture digitized using photogrammetry. A 50 cm × 50 cm rock sample of Kuru grey granite with a thoroughgoing fracture was digitized. The data was collected using a high-resolution digital camera and four low-cost cameras. The aperture and surface roughness were measured, and the influence of the camera type and 3D model rasterization on the measurement results was quantified. The results showed that low-cost cameras and smartphones can be used for generating 3D models for accurate measurement of physical aperture and roughness of rock fractures. However, the selection of appropriate rasterization grid interval plays a key role in accurate estimations. For measuring the physical aperture from the photogrammetric 3D models, reducing rasterization grid interval results in less scattered measurement results and a small rasterization grid interval of 0.1 mm is recommended. For roughness measurements, increasing the grid interval results in smaller measurement errors, and therefore a larger rasterization grid interval of 0.5 mm is recommended for high-resolution smartphones and 1 mm for other low-cost cameras. Full article
(This article belongs to the Special Issue Sensors and Measurements in Geotechnical Engineering)
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29 pages, 10220 KiB  
Article
The Technical Challenges for Applying Unsaturated Soil Sensors to Conduct Laboratory-Scale Seepage Experiments
by Guanxi Yan, Thierry Bore, Habibullah Bhuyan, Stefan Schlaeger and Alexander Scheuermann
Sensors 2022, 22(10), 3724; https://doi.org/10.3390/s22103724 - 13 May 2022
Cited by 9 | Viewed by 3381
Abstract
Although many unsaturated soil experiments have successfully delivered positive outcomes, most studies just concisely illustrated sensor techniques, because their main objectives focused on bridging research gaps. Inexperienced research fellows might rarely follow up those techniques, so they could encounter very trivial and skill-demanding [...] Read more.
Although many unsaturated soil experiments have successfully delivered positive outcomes, most studies just concisely illustrated sensor techniques, because their main objectives focused on bridging research gaps. Inexperienced research fellows might rarely follow up those techniques, so they could encounter very trivial and skill-demanding difficulties, undermining the quality of experimental outcomes. With a motivation to avoid those, this work introduces technical challenges in applying three sensor techniques: high precision tensiometer, spatial time-domain reflectometry (spatial TDR) and digital bench scales, which were utilized to measure three fundamental variables: soil suction, moisture content and accumulative outflow. The technical challenges are comprehensively elaborated from five aspects: the functional mechanism, assembling/manufacturing approaches, installation procedure, simultaneous data-logging configurations and post data/signal processing. The conclusions drawn in this work provide sufficient technical details of three sensors in terms of the aforementioned five aspects. This work aims to facilitate any new research fellows who carry out laboratory-scale soil column tests using the three sensors mentioned above. It is also expected that this work will salvage any experimenters having troubleshooting issues with those sensors and help researchers bypass those issues to focus more on their primary research interests. Full article
(This article belongs to the Special Issue Sensors and Measurements in Geotechnical Engineering)
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21 pages, 1814 KiB  
Article
Low-Power, Flexible Sensor Arrays with Solderless Board-to-Board Connectors for Monitoring Soil Deformation and Temperature
by Stijn Wielandt, Sebastian Uhlemann, Sylvain Fiolleau and Baptiste Dafflon
Sensors 2022, 22(7), 2814; https://doi.org/10.3390/s22072814 - 06 Apr 2022
Cited by 6 | Viewed by 2870
Abstract
Landslides are a global and frequent natural hazard, affecting many communities and infrastructure networks. Technological solutions are needed for long-term, large-scale condition monitoring of infrastructure earthworks or natural slopes. However, current instruments for slope stability monitoring are often costly, require a complex installation [...] Read more.
Landslides are a global and frequent natural hazard, affecting many communities and infrastructure networks. Technological solutions are needed for long-term, large-scale condition monitoring of infrastructure earthworks or natural slopes. However, current instruments for slope stability monitoring are often costly, require a complex installation process and/or data processing schemes, or have poor resolution. Wireless sensor networks comprising low-power, low-cost sensors have been shown to be a crucial part of landslide early warning systems. Here, we present the development of a novel sensing approach that uses linear arrays of three-axis accelerometers for monitoring changes in sensor inclination, and thus the surrounding soil’s deformation. By combining these deformation measurements with depth-resolved temperature measurements, we can link our data to subsurface thermal–hydrological regimes where relevant. In this research, we present a configuration of cascaded I2C sensors that (i) have ultra-low power consumption and (ii) enable an adjustable probe length. From an electromechanical perspective, we developed a novel board-to-board connection method that enables narrow, semi-flexible sensor arrays and a streamlined assembly process. The low-cost connection method relies on a specific FR4 printed circuit board design that allows board-to-board press fitting without using electromechanical components or solder connections. The sensor assembly is placed in a thin, semi-flexible tube (inner diameter 6.35 mm) that is filled with an epoxy compound. The resulting sensor probe is connected to an AA-battery-powered data logger with wireless connectivity. We characterize the system’s electromechanical properties and investigate the accuracy of deformation measurements. Our experiments, performed with probes up to 1.8 m long, demonstrate long-term connector stability, as well as probe mechanical flexibility. Furthermore, our accuracy analysis indicates that deformation measurements can be performed with a 0.390 mm resolution and a 95% confidence interval of ±0.73 mm per meter of probe length. This research shows the suitability of low-cost accelerometer arrays for distributed soil stability monitoring. In comparison with emerging low-cost measurements of surface displacement, our approach provides depth-resolved deformation, which can inform about shallow sliding surfaces. Full article
(This article belongs to the Special Issue Sensors and Measurements in Geotechnical Engineering)
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11 pages, 21419 KiB  
Communication
Effect of Wave Attenuation on Shear Wave Velocity Determination Using Bender Element Tests
by Yanbin Gao, Xiaojun Zheng, Hao Wang and Wenkang Luo
Sensors 2022, 22(3), 1263; https://doi.org/10.3390/s22031263 - 07 Feb 2022
Cited by 2 | Viewed by 2050
Abstract
Wave attenuation is a widespread physical phenomenon in most acoustic tests, but there is a scarcity of quantitative investigations into the influence of wave attenuation on the determination of shear wave travel time in bender element tests. To ascertain this attenuation effect, a [...] Read more.
Wave attenuation is a widespread physical phenomenon in most acoustic tests, but there is a scarcity of quantitative investigations into the influence of wave attenuation on the determination of shear wave travel time in bender element tests. To ascertain this attenuation effect, a series of bender element tests were conducted on clay samples with different lengths under unconfined conditions. The experimental results suggest that the real first peak of the received signal attenuates gradually with the increase of the sample length and even becomes undistinguished when the sample length exceeds a limit. This phenomenon results in misinterpretation of the wave travel time using the time domain method. In this study, the shear wave travel time is misinterpreted when wave travel distance over approximately 80 mm, leading to underestimation of the VS by 17% for the peak-to-peak approach and 10% for the arrival-to-arrival method. Therefore, besides the near field effect and boundary reflection, the wave attenuation effect turned out to be an important factor influencing the determination of VS using the time domain method. Accordingly, it is advisable to predetermine the limit test distance for a specific testing system under conditions, particularly for long distance testing. Full article
(This article belongs to the Special Issue Sensors and Measurements in Geotechnical Engineering)
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15 pages, 2910 KiB  
Article
Understanding the Influence of Rock Content on Streaming Potential Phenomenon of Soil–Rock Mixture: An Experimental Study
by Xin Zhang, Mingjie Zhao and Kui Wang
Sensors 2022, 22(2), 585; https://doi.org/10.3390/s22020585 - 13 Jan 2022
Cited by 1 | Viewed by 1365
Abstract
To applicate streaming potential phenomenon to study the seepage feature in the soil–rock mixture (SRM), research on the variation in the streaming potential phenomenon of SRM is the precondition. This paper deals, in assistance with the streaming potential test apparatus, with the streaming [...] Read more.
To applicate streaming potential phenomenon to study the seepage feature in the soil–rock mixture (SRM), research on the variation in the streaming potential phenomenon of SRM is the precondition. This paper deals, in assistance with the streaming potential test apparatus, with the streaming potential effect response of SRM subjected to different rock contents. The test results show that when the rock content increases from 10% to 30%, the streaming potential coupling coefficient increases with the increases in rock content at 85% compactness and 0.01 mol L−1 salinity. When the rock content is more than 30%, the streaming potential coupling coefficient decreases with the increases in rock content. As the rock content increases, the permeability coefficient has a negative correlation with the streaming potential coupling coefficient. The streaming potential increases first and then goes down with the increases in rock content, and the streaming potential decreases significantly when the rock content exceeds 50%. The findings indicate that the rock content is the key structural factor that restricts the streaming potential phenomenon of the SRM. Full article
(This article belongs to the Special Issue Sensors and Measurements in Geotechnical Engineering)
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26 pages, 16902 KiB  
Article
Application of Laser Scanning to Assess the Roughness of the Diaphragm Wall for the Estimation of Earth Pressure
by Marek Wyjadłowski, Zbigniew Muszyński and Paulina Kujawa
Sensors 2021, 21(21), 7275; https://doi.org/10.3390/s21217275 - 01 Nov 2021
Cited by 3 | Viewed by 1995
Abstract
The correct estimation of earth pressure is important for the design of earth retaining structures and depends, among others, on the surface morphology of retaining structures. The diaphragm wall created as a protection of a deep excavation located in an urbanized area was [...] Read more.
The correct estimation of earth pressure is important for the design of earth retaining structures and depends, among others, on the surface morphology of retaining structures. The diaphragm wall created as a protection of a deep excavation located in an urbanized area was selected as a research object. Terrestrial Laser Scanning (TLS) was used for the investigation of the unique surface (in real-world dimension) obtained by tremieying the concrete in different soil layers. An original and innovative procedure for concrete surface description was developed, which includes steps from the TLS measurement to the determination of the roughness parameters. The tested samples from anthropogenic soil, medium sand, and sandy gravel, map the real diaphragm wall surface. The surface roughness parameters in different soil layers were compared with the reference surface obtained by cast against steel formwork. The following parameters: Sa, Sdr, and Vmc are indicated as being the most useful in numerical description of the concrete surface type and in allowing the determination of the soil surface friction. The novelty of this study is the estimation of the parameter δ (friction angle between the retaining wall surface and the soil), which is, among others, a function of the wall surface roughness. The influence of the type of surface on earth pressure are generally recognized in laboratory tests. Based on the estimated in situ values of δ, the more reliable active and passive pressure coefficients Ka, Kp were calculated for the tested soil layers. The conducted study has a practical significance for designing of retaining construction and makes progress in determination of surface roughness required in Eurocode 7. Full article
(This article belongs to the Special Issue Sensors and Measurements in Geotechnical Engineering)
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23 pages, 13749 KiB  
Article
Assessment of Stress in the Soil Surrounding the Axially Loaded Model Pile by Thin, Flexible Sensors
by Krzysztof Żarkiewicz and Waleed Qatrameez
Sensors 2021, 21(21), 7214; https://doi.org/10.3390/s21217214 - 29 Oct 2021
Cited by 4 | Viewed by 2513
Abstract
Foundation piles transfer the applied vertical load to the surrounding soil by skin friction and base resistance. These two components induce stress in the soil. The load transfer is still not fully recognized, and some pile load tests analyses have raised many doubts. [...] Read more.
Foundation piles transfer the applied vertical load to the surrounding soil by skin friction and base resistance. These two components induce stress in the soil. The load transfer is still not fully recognized, and some pile load tests analyses have raised many doubts. The present paper aimed to measure the stress levels during pile load tests in laboratory conditions. This research examined the possibilities of using thin, flexible sensors in measuring the stress in soil. Two sensors were used: tactile pressure sensor with mapping system and color film pressure sensors with digital analyzing. Calibration and preliminary tests of the sensors have been described. This calibration proved that this kind of sensor could measure the stress in the soil in laboratory conditions. The results of stress distribution in the soil, shown as pressure maps, have been presented. Significant stress changes were observed in pile load tests. Rough and smooth piles were compared in the analyses. Stress distribution was the result of simultaneous interaction of pile skin and base. The knowledge about stresses surrounding the pile allows us to carry out a deeper analysis of the pile–soil interaction. Full article
(This article belongs to the Special Issue Sensors and Measurements in Geotechnical Engineering)
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15 pages, 6428 KiB  
Article
Measurement of Axial Strain of Geogrid by Optical Sensors
by Marian Drusa, Ladislav Kais, Jozef Dubovan, Miroslav Markovic, Frantisek Bahleda and Martin Mecar
Sensors 2021, 21(19), 6404; https://doi.org/10.3390/s21196404 - 25 Sep 2021
Cited by 2 | Viewed by 1828
Abstract
In recent years, the technology of optical fibers has rapidly gained ground in many areas of science and industry, including the construction industry. In this article, the technology of optical fibers based on a fiber Bragg grating (FBG) was used to determine tensile [...] Read more.
In recent years, the technology of optical fibers has rapidly gained ground in many areas of science and industry, including the construction industry. In this article, the technology of optical fibers based on a fiber Bragg grating (FBG) was used to determine tensile forces acting in a basal reinforcement of a scaled down physical model, which included piled embankment and basal reinforcement. Installing FBG sensors on the geogrid made monitoring of axial strains possible, thus allowing determination of the behavior of the basal reinforcement of the piled embankment. On the basis of three tests performed on the physical model, numerical model calibration with the physical model was carried out using the software PLAXIS 3D Tunnel 2.4. The results showed accurate predictions, especially for the low and middle part of the measured deformations where the numerical analysis proposed a solution that can be considered as safe. Installing FBG sensors on biaxial geogrids was a bold idea that was not easy to implement. However, other possibilities have been successfully tested, such as high-frequency measurements of the response of reinforced soil structure under dynamic loading. Full article
(This article belongs to the Special Issue Sensors and Measurements in Geotechnical Engineering)
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19 pages, 4408 KiB  
Article
Design of a Digital 3D Model of Transport–Technological Environment of Open-Pit Mines Based on the Common Use of Telemetric and Geospatial Information
by Igor Temkin, Alexander Myaskov, Sergey Deryabin, Iliya Konov and Alexander Ivannikov
Sensors 2021, 21(18), 6277; https://doi.org/10.3390/s21186277 - 18 Sep 2021
Cited by 16 | Viewed by 3285
Abstract
This article is devoted to the issues of processing and analysis of heterogeneous information related to the functioning of mining transport equipment, which becomes available for analysis within the framework of modern technological operations control systems in open-pit mines. These issues are very [...] Read more.
This article is devoted to the issues of processing and analysis of heterogeneous information related to the functioning of mining transport equipment, which becomes available for analysis within the framework of modern technological operations control systems in open-pit mines. These issues are very relevant to robotized technological operations. The paper gives a brief overview of the modern landscape of the autonomous haulage systems management problems, the features of the platform approach to solving the problem of managing unmanned transport and technological processes in open pits are considered. The concept of an agent-based approach to the modeling of an open-pit mining is described in detail on the basis of the interaction of three systems: technical, infrastructural–technological, and geostructural. Some features of the developed platform architecture integration of heterogeneous information are discussed. The principles of information integration are considered in detail when constructing a dynamic 3D model (digital twin) of infrastructure and technological system elements using large arrays of telemetric data. The results of building digital models of open-pit technological roads are presented. The resulting models are comparatively analyzed in the process of optimizing of the interaction of technical autonomous mobile agents and elements of technological infrastructure. Full article
(This article belongs to the Special Issue Sensors and Measurements in Geotechnical Engineering)
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17 pages, 4425 KiB  
Article
The Application of a Sonic Probe Extensometer for the Detection of Rock Salt Flow Field in Underground Convergence Monitoring
by Zbigniew Szczerbowski and Zbigniew Niedbalski
Sensors 2021, 21(16), 5562; https://doi.org/10.3390/s21165562 - 18 Aug 2021
Cited by 4 | Viewed by 2461
Abstract
Special regulations have been laid down to establish the principles and requirements for the safety and serviceability of old mining workings which are adapted for tourism. To comply with these regulations the measurements were taken in the Bochnia Salt Mine, which has been [...] Read more.
Special regulations have been laid down to establish the principles and requirements for the safety and serviceability of old mining workings which are adapted for tourism. To comply with these regulations the measurements were taken in the Bochnia Salt Mine, which has been in use for 800 years. The presented work demonstrates the use of a sonic probe extensometer in connection with the obtained results of displacement measurements in intact rocks surrounding the gallery. There were also test measurements carried out for determination of the real accuracy of the instrument. The presented study of deformations detected by electromagnetic extensometer measurements is presumed to be the first time that research has been made in salt mines operating in rock mass affected by tectonic stress. The paper presents the process of rock salt flow into the gallery observed over a period of 3 years. It is an unprecedented depiction of salt deformation subjected to natural stresses. One of the more surprising results presented here is the discovery of the occurrence of a specific distribution of strain around the measured gallery. The results of measurements showed that the southern part of the intact rock mass surrounding the passage is more compressed (strain rate 3.6 mm/m/year) than the northern one (strain rate 1.6 mm/m/year). This illustrates the presence and influence of additional tectonic effects resulting from the Carpathian push. These observations represent a new kind of research into tectonic stress and tectonic activity in underground measurements. Full article
(This article belongs to the Special Issue Sensors and Measurements in Geotechnical Engineering)
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22 pages, 4420 KiB  
Article
The Identification of the Uncertainty in Soil Strength Parameters Based on CPTu Measurements and Random Fields
by Joanna Pieczyńska-Kozłowska, Irena Bagińska and Marek Kawa
Sensors 2021, 21(16), 5393; https://doi.org/10.3390/s21165393 - 10 Aug 2021
Cited by 12 | Viewed by 2861
Abstract
The present paper responds to the challenge of modeling uncertainty in soil strength parameters concerning its spatial variability in a situation of limited soil information. Understanding this uncertainty allows for the management of the risk of geotechnical structure failure. In the present work, [...] Read more.
The present paper responds to the challenge of modeling uncertainty in soil strength parameters concerning its spatial variability in a situation of limited soil information. Understanding this uncertainty allows for the management of the risk of geotechnical structure failure. In the present work, this uncertainty is identified based on signals from the cone penetration test (CPT) device. Signals are directly transformed using existing interpretation methods (typically used as a source of mean values of parameters for a given range of depths) to obtain depth-varying effective strength parameters of the soil. The process is performed by incorporating data from two case studies from different locations in similar soil materials. First, Keswick clay from Australia, for which the results of both CPT and laboratory tests are available, is examined. Second, to further verify the obtained results, the soil from Poland called Świerzna clay, for which only CPT signals were available, is also tested. As shown, the variability of the transformed signals can be a good source of information for identifying uncertainty in soil strength. It agrees well with literature data and can be used to identify random fields describing soil parameters. Full article
(This article belongs to the Special Issue Sensors and Measurements in Geotechnical Engineering)
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15 pages, 6875 KiB  
Article
Protection and Installation of FBG Strain Sensor in Deep Boreholes for Subsurface Faults Behavior Monitoring
by Sang-Jin Choi, Kwon Gyu Park, Chan Park and Changhyun Lee
Sensors 2021, 21(15), 5170; https://doi.org/10.3390/s21155170 - 30 Jul 2021
Cited by 7 | Viewed by 2619
Abstract
Fiber optic sensors are gradually replacing electrical sensors in geotechnical applications owing to their immunity to electrical interference, durability, and cost-effectiveness. However, additional protective measures are required to prevent loss of functionality due to damage to the sensors, cables, or connection parts (splices [...] Read more.
Fiber optic sensors are gradually replacing electrical sensors in geotechnical applications owing to their immunity to electrical interference, durability, and cost-effectiveness. However, additional protective measures are required to prevent loss of functionality due to damage to the sensors, cables, or connection parts (splices and/or connectors) during installation and completion processes in borehole applications. We introduce two cases of installing fiber Bragg grating (FBG) strain sensors in 1 km boreholes to monitor the behavior of deep subsurface faults. We present our fiber-reinforced plastic (FRP) forming schemes to protect sensors and splices. We also present uniaxial load test and post-completion monitoring results for assessing the effects and performance of the protective measures. The uniaxial load test and post-completion monitoring show that FBG sensors are well protected by FRP forming without significant impact on sensor performance itself and that they are successfully installed in deep boreholes. In addition to summarizing our learning from experiences, we also suggest several points for consideration to improve the applicability of FBG sensors in borehole environment of the geotechnical field. Full article
(This article belongs to the Special Issue Sensors and Measurements in Geotechnical Engineering)
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25 pages, 13346 KiB  
Article
New Distributed Fibre Optic 3DSensor with Thermal Self-Compensation System: Design, Research and Field Proof Application Inside Geotechnical Structure
by Łukasz Bednarski, Rafał Sieńko, Marcin Grygierek and Tomasz Howiacki
Sensors 2021, 21(15), 5089; https://doi.org/10.3390/s21155089 - 27 Jul 2021
Cited by 14 | Viewed by 3219
Abstract
Thanks to the dynamic development of advanced building technologies as well as the growing awareness, experience and responsibilities of engineers, structural health monitoring systems (SHM) are increasingly applied in civil engineering and geotechnical applications. This is also facilitated by the construction law and [...] Read more.
Thanks to the dynamic development of advanced building technologies as well as the growing awareness, experience and responsibilities of engineers, structural health monitoring systems (SHM) are increasingly applied in civil engineering and geotechnical applications. This is also facilitated by the construction law and standard requirements, e.g., the observation method for geotechnical structures described in the Eurocode 7. Still, the most common approach is to apply spot sensors in selected points of the structure to validate theoretical models, numerical simulations and support technical assessments by involving statistic and approximation methods. The main limitation of spot sensing is the inability to detect localized damages such as cracks, fractures, sinkholes or shear planes. Thus, such analysis is subject to considerable uncertainty, especially within geotechnical structures, characterized by random mechanical parameters that change with location, but also over time. Another approach is based on distributed fibre optic sensors (DFOS), which are finding a growing acceptance in laboratory and field projects, overcoming limitations of conventional measurements. The design and applications of new DFOS dedicated for 3D displacement sensing are described hereafter in the article. The novelty of the presented solution lies in several features, including design, application, production technology and materials. This article is focused on the operational rules governing DFOS and proving their effectiveness in laboratory and geotechnical field applications. Full article
(This article belongs to the Special Issue Sensors and Measurements in Geotechnical Engineering)
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20 pages, 13655 KiB  
Article
Influence of Load Plates Diameters, Shapes of Columns and Columns Spacing on Results of Load Plate Tests of Columns Formed by Dynamic Replacement
by Sławomir Kwiecień
Sensors 2021, 21(14), 4868; https://doi.org/10.3390/s21144868 - 16 Jul 2021
Cited by 3 | Viewed by 1615
Abstract
The dynamic replacement method is used to strengthen the subgrade of objects, usually up to 5 to 6 m thick. After the improvement process, acceptance tests in the form of load testing are carried out. Interpretation of the test results can cause some [...] Read more.
The dynamic replacement method is used to strengthen the subgrade of objects, usually up to 5 to 6 m thick. After the improvement process, acceptance tests in the form of load testing are carried out. Interpretation of the test results can cause some difficulties. Dynamic replacement results in a situation where columns of different shapes, loaded with plates of diameters usually smaller than the head diameter and in the vicinity of adjacent columns, are subjected to load tests. In order to demonstrate the influence of these factors, a spatial model of soil strengthened by dynamic replacement, comprising four material zones, was calibrated on the basis of load testing. The following models were used in the analysis: linear-elastic, elastic–perfectly plastic (Coulomb–Mohr) and elastic–plastic with isotropic hardening (Modified Cam-Clay). This formed the basis for 105 numerical models, which took into account the actual shapes of the columns made at various spacings, subjected to load tests with plates of various diameters. The analyses of the settlements, calculated moduli and stress distribution in the loaded system showed how the results were significantly influenced by mentioned factors. This implies that the interpretation of the results of load tests should be based on advanced spatial numerical analyses, using appropriate constitutive models and including the considered factors. Full article
(This article belongs to the Special Issue Sensors and Measurements in Geotechnical Engineering)
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20 pages, 10161 KiB  
Article
New Hydraulic Sensor for Distributed and Automated Displacement Measurements with Temperature Compensation System
by Łukasz Bednarski, Rafał Sieńko, Piotr Kanty and Tomasz Howiacki
Sensors 2021, 21(14), 4678; https://doi.org/10.3390/s21144678 - 08 Jul 2021
Cited by 6 | Viewed by 2562
Abstract
Structural health monitoring (SHM) is a challenging task, especially in the context of ground and geotechnical structures. They are characterized by a set of random mechanical parameters, depending on the location but also changing with external conditions (such as humidity or temperature) over [...] Read more.
Structural health monitoring (SHM) is a challenging task, especially in the context of ground and geotechnical structures. They are characterized by a set of random mechanical parameters, depending on the location but also changing with external conditions (such as humidity or temperature) over time. Theoretical predictions and results of numerical simulations are, therefore, considerably uncertain. On the other hand, measurements aimed at improving construction and operation of such structures are very often performed only in selected points, which significantly increases the risk of data misinterpretation. Reliable measurement data related to structural condition are of the great importance because they allow for improvement of work quality but also reduce construction time and, thereby, save money. That is why scientists and engineers are still searching for new measurement solutions to overcome existing limitations. The purpose of the study is to present the design and practical application of a new hydraulic sensor dedicated to vertical displacement sensing. The novelty of the presented solution lies in several features, including the possibility of performing automatic measurements and compensating the results due to temperature effects. The article describes the sensor’s design, including the concept of a thermal compensation system and example results from laboratory tests, where the sensor’s performance was investigated in a dual-zone thermal chamber. Finally, the sensor was installed within the field conditions under an embankment constructed above the improved substrate. Example results verified by reference distributed fiber optic technique are presented and discussed hereafter, raising high prospects in the context of possible structural health monitoring applications of the new solution. Full article
(This article belongs to the Special Issue Sensors and Measurements in Geotechnical Engineering)
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19 pages, 10164 KiB  
Article
Examples of the Use of the ARAMIS 3D Measurement System for the Susceptibility to Deformation Tests for the Selected Mixtures of Coal Mining Wastes
by Konrad Walotek, Joanna Bzówka and Adrian Ciołczyk
Sensors 2021, 21(13), 4600; https://doi.org/10.3390/s21134600 - 05 Jul 2021
Cited by 9 | Viewed by 2947
Abstract
This paper presents the ARAMIS 3D system and examples of deformation susceptibility test results made on mixtures of coal mining waste and recycled tire rubber bound with the use of hydraulic binders. The ARAMIS 3D system is a measurement tool based on 3D [...] Read more.
This paper presents the ARAMIS 3D system and examples of deformation susceptibility test results made on mixtures of coal mining waste and recycled tire rubber bound with the use of hydraulic binders. The ARAMIS 3D system is a measurement tool based on 3D scanning of the surface of the tested material. On the basis of the obtained 3D video image, the system allows for the continuous observation of the displacements occurring on the surface of the tested object during its load. This allows for a very detailed determination of the deformation distribution during the material loading. These types of measurement systems can be very useful, especially in the case of testing composite materials and testing materials under cyclic load conditions. Full article
(This article belongs to the Special Issue Sensors and Measurements in Geotechnical Engineering)
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24 pages, 14467 KiB  
Article
Combining Ground Based Remote Sensing Tools for Rockfalls Assessment and Monitoring: The Poggio Baldi Landslide Natural Laboratory
by Saverio Romeo, Antonio Cosentino, Francesco Giani, Giandomenico Mastrantoni and Paolo Mazzanti
Sensors 2021, 21(8), 2632; https://doi.org/10.3390/s21082632 - 08 Apr 2021
Cited by 15 | Viewed by 4871
Abstract
Nowadays the use of remote monitoring sensors is a standard practice in landslide characterization and monitoring. In the last decades, technologies such as LiDAR, terrestrial and satellite SAR interferometry (InSAR) and photogrammetry demonstrated a great potential for rock slope assessment while limited studies [...] Read more.
Nowadays the use of remote monitoring sensors is a standard practice in landslide characterization and monitoring. In the last decades, technologies such as LiDAR, terrestrial and satellite SAR interferometry (InSAR) and photogrammetry demonstrated a great potential for rock slope assessment while limited studies and applications are still available for ArcSAR Interferometry, Gigapixel imaging and Acoustic sensing. Taking advantage of the facilities located at the Poggio Baldi Landslide Natural Laboratory, an intensive monitoring campaign was carried out on May 2019 using simultaneously the HYDRA-G ArcSAR for radar monitoring, the Gigapan robotic system equipped with a DSLR camera for photo-monitoring purposes and the DUO Smart Noise Monitor for acoustic measurements. The aim of this study was to evaluate the potential of each monitoring sensor and to investigate the ongoing gravitational processes at the Poggio Baldi landslide. Analysis of multi-temporal Gigapixel-images revealed the occurrence of 84 failures of various sizes between 14–17 May 2019. This allowed us to understand the short-term evolution of the rock cliff that is characterized by several impulsive rockfall events and continuous debris production. Radar displacement maps revealed a constant movement of the debris talus at the toe of the main rock scarp, while acoustic records proved the capability of this technique to identify rockfall events as well as their spectral content in a narrow range of frequencies between 200 Hz to 1000 Hz. This work demonstrates the great potential of the combined use of a variety of remote sensors to achieve high spatial and temporal resolution data in the field of landslide characterization and monitoring. Full article
(This article belongs to the Special Issue Sensors and Measurements in Geotechnical Engineering)
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18 pages, 6224 KiB  
Article
Advantages of IoT-Based Geotechnical Monitoring Systems Integrating Automatic Procedures for Data Acquisition and Elaboration
by Andrea Carri, Alessandro Valletta, Edoardo Cavalca, Roberto Savi and Andrea Segalini
Sensors 2021, 21(6), 2249; https://doi.org/10.3390/s21062249 - 23 Mar 2021
Cited by 15 | Viewed by 3406
Abstract
Monitoring instrumentation plays a major role in the study of natural phenomena and analysis for risk prevention purposes, especially when facing the management of critical events. Within the geotechnical field, data collection has traditionally been performed with a manual approach characterized by time-expensive [...] Read more.
Monitoring instrumentation plays a major role in the study of natural phenomena and analysis for risk prevention purposes, especially when facing the management of critical events. Within the geotechnical field, data collection has traditionally been performed with a manual approach characterized by time-expensive on-site investigations and monitoring devices activated by an operator. Due to these reasons, innovative instruments have been developed in recent years in order to provide a complete and more efficient system thanks to technological improvements. This paper aims to illustrate the advantages deriving from the application of a monitoring approach, named Internet of natural hazards, relying on the Internet of things principles applied to monitoring technologies. One of the main features of the system is the ability of automatic tools to acquire and elaborate data independently, which has led to the development of dedicated software and web-based visualization platforms for faster, more efficient and accessible data management. Additionally, automatic procedures play a key role in the implementation of early warning systems with a near-real-time approach, providing a valuable tool to the decision-makers and authorities responsible for emergency management. Moreover, the possibility of recording a large number of different parameters and physical quantities with high sampling frequency allows to perform meaningful statistical analyses and identify cause–effect relationships. A series of examples deriving from different case studies are reported in this paper in order to present the practical implications of the IoNH approach application to geotechnical monitoring. Full article
(This article belongs to the Special Issue Sensors and Measurements in Geotechnical Engineering)
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18 pages, 5711 KiB  
Article
Analytical Modelling of MSW Landfill Surface Displacement Based on GNSS Monitoring
by Dana Adamcová, Stanislav Bartoň, Piotr Osinski, Grzegorz Pasternak, Anna Podlasek, Magdalena Daria Vaverková and Eugeniusz Koda
Sensors 2020, 20(21), 5998; https://doi.org/10.3390/s20215998 - 22 Oct 2020
Cited by 6 | Viewed by 2506
Abstract
Displacements of landfills play an important role in the reclamation process and geotechnical safety improvement of such sites. Landfill settlements are defined as a vertical displacement of waste body due to compression, degradable nature of the waste, and creep phenomenon of the waste [...] Read more.
Displacements of landfills play an important role in the reclamation process and geotechnical safety improvement of such sites. Landfill settlements are defined as a vertical displacement of waste body due to compression, degradable nature of the waste, and creep phenomenon of the waste particles. Waste composition is more diverse than natural soil. Thus, it has to be properly placed and compacted since the landfill body will continuously settle down. Several models of the landfill displacement estimation have already been developed. The aim of the present study was: (i) to review the methods of landfill settlements computation and (ii) to propose the model allowing landfill body displacements simulation based on monitoring datasets applying a Global Navigation Satellite Systems (GNSS) measurement. The new model employs Gauss-Newton iteration and Runge-Kutta methods to estimate landfill surface displacements. The objectives were to analyse and mathematically describe the landfill body displacements. The GNSS geodetic survey and computations allowed concluding that the landfill body has been transformed over the years. The results revealed that the curves of waste displacement are in agreement with the measured total displacement of the landfill, and all curves corresponding to waste displacement are perpendicular to the active edge of the landfill. In the period of a maximum of 4.5 years after the waste deposition with a layer of up to 16.2 m thickness, the phenomenon of expansion was observed, which then disappears, and more settlement occurs due to the gravity of upper layers. The analysed landfill as a whole does not experience significant displacements. Neither of the slope failures are observed, even for large inclination. Full article
(This article belongs to the Special Issue Sensors and Measurements in Geotechnical Engineering)
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Review

Jump to: Research

27 pages, 9566 KiB  
Review
Modern Displacement Measuring Systems Used in Geotechnical Laboratories: Advantages and Disadvantages
by Małgorzata Jastrzębska
Sensors 2021, 21(12), 4139; https://doi.org/10.3390/s21124139 - 16 Jun 2021
Cited by 5 | Viewed by 4317
Abstract
The paper presents the contemporary displacement measurement systems used in geotechnical laboratories during the determination of soil precise mechanical parameters, e.g., the shear modules G: initial and in the range of small and very small strains. In the laboratory, researchers use standard sensors [...] Read more.
The paper presents the contemporary displacement measurement systems used in geotechnical laboratories during the determination of soil precise mechanical parameters, e.g., the shear modules G: initial and in the range of small and very small strains. In the laboratory, researchers use standard sensors for measuring deformation, pressure, and force as well as modern measuring systems such as linear variable differential transformers (LVDT), proximity transducers (PT), magnetic encoder sensors with fiber Bragg grating (FBG), or methods based on laser or X-ray measurement. None of the measurements are universal and their use depends on the type of soil (cohesive, non-cohesive), its condition (loose or dense, stiff or very soft), and its characteristic properties (e.g., organic soil, swelling soil). This study points out the interesting equipment solutions and presents the guidelines for selecting appropriate methods of deformation measurement. Full article
(This article belongs to the Special Issue Sensors and Measurements in Geotechnical Engineering)
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