Advanced Research in Soil and Rock Behavior for Geotechnical and Geohazard Engineering

A special issue of Applied Sciences (ISSN 2076-3417). This special issue belongs to the section "Earth Sciences".

Deadline for manuscript submissions: closed (31 July 2023) | Viewed by 25201

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Guest Editor
Badong National Observation and Research Station of Geohazards, China University of Geosciences, 388 Lumo Road, Wuhan 430074, China
Interests: unsaturated soil mechanics; pile-soil interaction; expansive soil; geohazards mitigation; geological engineering; rock mechanics

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Guest Editor
College of Marine Science and Technology, China University of Geosciences, 388 Lumo Road, Wuhan 430074, China
Interests: submarine landslide; material point method; GPU parallelization; free falling penetrometer
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Special Issue Information

Dear Colleagues,

Rock formations and soil deposits have widely varying characteristics, which is due to the inherent nature and diversity of the geological processes of such formations. As such, scientists and engineers in the field of geotechnical and geological engineering are confronted with a greater degree of uncertainty in the realistic assessment of the engineering behavior of these geological materials than of other processed and manufactured construction materials. The rock masses and/or soil deposits support or exert pressure on geotechnical structures, thereby affecting their safety and performance. Geological hazards, such as landslides, debris flows and rockfalls, are essentially related to the failure process of soil and rock mass. Therefore, the sophisticated analysis and reasonable characterization of soil and rock behavior is a fundamental requirement for geotechnical study and application, as well as geohazards mitigation.

This Special Issue is devoted to publishing new advancements in the theoretical, experimental and numerical aspects of soil and rock behavior, providing access to advanced, innovative and high-quality research and technical papers across the fields of soil and rock mechanics, geotechnical engineering, engineering geology and environmental geotechnics. A wide range of related works is welcome, which may include soil/rock mechanical properties and deformation characteristics, site characterization, foundations, excavations, dams and embankments, slopes, landslides, ground improvement, hydrogeology and contaminant hydrogeology, geological disposal of radioactive wastes, geosynthetics, offshore engineering, georisk assessment and management and so on.

We cordially invite you to submit a paper to this exciting Special Issue. Your papers will be highly advertised and widely circulated. Everyone will be able to easily access and read them, as this Special Issue will be freely available online. It would be a pleasure for us if you would agree to participate.

Dr. Qingbing Liu
Dr. Youkou Dong
Guest Editors

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Keywords

  • soil mechanics
  • rock mechanics
  • constitutive model
  • soil reinforcement
  • rock/soil–structure interaction
  • geological hazards
  • geosynthetics
  • multiscale modeling

Published Papers (16 papers)

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Research

14 pages, 3600 KiB  
Article
Study of Gravelly Soil Core Material Using a Large-Scale Triaxial Wetting Test
by Yuyang Qin, Guoying Li, Zhankuan Mi and Kaifang Fan
Appl. Sci. 2023, 13(24), 13295; https://doi.org/10.3390/app132413295 - 15 Dec 2023
Viewed by 576
Abstract
Wetting deformation has a significant impact on dam safety, and is one of the leading causes of the long-term deformation of dams. For dams to operate safely, it is crucial to precisely estimate the extent of wetting deformation using a reasonable calculation model. [...] Read more.
Wetting deformation has a significant impact on dam safety, and is one of the leading causes of the long-term deformation of dams. For dams to operate safely, it is crucial to precisely estimate the extent of wetting deformation using a reasonable calculation model. This study describes the wetting deformation behavior of gravelly soil core material observed at a hydropower station using a large-scale triaxial wetting test, and the process, characteristics, and mechanism of the wetting deformation are analyzed. The results show that the direction of the wetting deformation exhibits different behaviors influenced by the stress levels. Compared with the significant changes in the wetting direction observed under low stress levels, the changes in the wetting direction under high stress levels appears to lag behind those in wetting deformation. The source of wetting deformation is thought to be the weakening of a material when it encounters water. Thus, a new calculation model of the wetting deformation of gravelly soil core material is proposed. In this model, the wetting strain ratio is in an exponential relationship with the stress levels, and the new model is used to simulate the triaxial wetting test on the gravelly soil core material; its validity and practicability are further evaluated, providing a new computational approach for analyzing the wetting deformation behavior of dams. Full article
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15 pages, 2671 KiB  
Article
An Investigation into the Influence of Sample Height on the Consolidation Behaviour of Dredged Silt
by Ronghua Hu, Ming Zhang and Jiaqi Wang
Appl. Sci. 2023, 13(18), 10419; https://doi.org/10.3390/app131810419 - 18 Sep 2023
Viewed by 573
Abstract
This study delves into the effects of sample height on consolidation behaviour, utilising the automatic air pressure consolidometer. Extensive tests were conducted on three varieties of dredged silt samples of varying heights from Qianwan, Shenzhen, China. The salient findings can be summarised as [...] Read more.
This study delves into the effects of sample height on consolidation behaviour, utilising the automatic air pressure consolidometer. Extensive tests were conducted on three varieties of dredged silt samples of varying heights from Qianwan, Shenzhen, China. The salient findings can be summarised as follows: (1) Compression curves for samples of different dimensions transitioned through three distinct phases: minimal load disturbance, elastic deformation, and plastic deformation. Notably, the void ratio during the latter two phases diminished as sample height increased. (2) A rising sample height corresponded to a reduced stable strain and compression index. Furthermore, the consolidation coefficient notably diminished with an escalation in the sample height, whereas the structural yield stress remained largely unaffected. (3) Given the disparate formation processes, stress histories, and material compositions between dredged and marine silts, the permeability coefficient of dredged silt was found to be superior to that of marine silt. Within the typical preloading pressure scope (50~300 kPa), the consolidation coefficient of dredged silt was lower compared to marine silt. However, as the consolidation pressure significantly surpassed this threshold, the coefficient disparity between the two silts narrowed. Full article
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21 pages, 7498 KiB  
Article
Impact of Soil Properties’ Spatial Correlation Lengths and Inclination on Permanent Slope Displacements Due to Earthquake Excitation
by Nikolaos Alamanis and Panagiotis Dakoulas
Appl. Sci. 2023, 13(17), 9868; https://doi.org/10.3390/app13179868 - 31 Aug 2023
Cited by 1 | Viewed by 592
Abstract
Natural disasters, when and where they occur, often cause serious social and economic consequences, which require an urgent solution to the problem. In particular, Greece, which is characterized by a complex geological structure and intense tectonic stress, has suffered and continues to suffer [...] Read more.
Natural disasters, when and where they occur, often cause serious social and economic consequences, which require an urgent solution to the problem. In particular, Greece, which is characterized by a complex geological structure and intense tectonic stress, has suffered and continues to suffer the consequences of such catastrophic phenomena. Among the various destructive phenomena recorded on the Earth’s surface, two of the most important problems are landslides and land subsidence. The above phenomena may cause, in addition to the serious case of loss of human life, a threat to the social and economic fabric affecting sustainability in general, i.e., the quality of life of an area (destruction of property, filling of reservoirs, blockage of streams and rivers, etc.). In fact, landslides are a phenomenon with enormous social and economic consequences, since apart from the financial burden due to the collapse of a technical project or the interruption of transportation, they are accompanied by the loss of human life. This research examines the stochastic characteristics of a slopes’ stability to investigate the variation range of permanent earthquake movements. More specifically, the influence of inclination as well as the lengths of the spatial correlation of ground are investigated. The method in the present study follows the development of arbitrary fields of soil properties, which follow the Gaussian distribution characterized by autocorrelation lengths lx and ly in the horizontal and vertical directions, respectively, mean value μ, standard deviation σ, and cross-correlation coefficients ρij. The estimation of permanent displacements is performed by the combination of the Local Average Subdivision algorithm and the FLAC software (Fast Lagrangian Analysis of Continua) used in the parametric investigation of this work. The results of this research showed that the spatial correlation of the properties has an important impact on the permanent displacements of slopes caused by strong earthquake excitations. Full article
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22 pages, 10363 KiB  
Article
Creep Characteristics of a Strongly Weathered Argillaceous Sandstone Sliding Zone and the Disaster Evolution Mechanism of the Huaipa Landslide, China
by Jinyu Dong, Yawen Zhao, Handong Liu, Jiancang Zhao, Zhimin Zhang, Qiuhui Chi and Jihong Yang
Appl. Sci. 2023, 13(15), 8579; https://doi.org/10.3390/app13158579 - 25 Jul 2023
Cited by 2 | Viewed by 879
Abstract
The creep characteristics of sliding zones strongly influence slope deformation and long-term stability, as well as the occurrence of landslide catastrophes. In this paper, large-scale triaxial creep tests were performed on the strongly weathered argillaceous sandstone sliding zone of the Huaipa landslide in [...] Read more.
The creep characteristics of sliding zones strongly influence slope deformation and long-term stability, as well as the occurrence of landslide catastrophes. In this paper, large-scale triaxial creep tests were performed on the strongly weathered argillaceous sandstone sliding zone of the Huaipa landslide in the Henan Province, China, to study its creep characteristics and long-term strength in natural and saturated states. Three-dimensional numerical simulations were conducted to analyze the deformation creep law and catastrophic evolution mechanism of the slope after excavation and rainfall. The results show that the sliding zone underwent appreciable creep deformation prior to failure, and that the progression of specimen damage with an increasing stress level followed decay creep → steady creep → accelerated creep. The stress level played a decisive role in the creep deformation, with higher stress levels resulting in higher instantaneous displacement, creep displacement, and longer times required to reach steady creep. The stress level also determined the specimen’s creep stage. When the stress level was low, the adjustment of the specimen’s internal structure was dominated by air space compression and particle movement, whereas particle fragmentation mostly occurred at high stress levels. The long-term rock strength was approximately 62–66% of the instantaneous strength, the internal friction angle decreased by approximately 8° relative to the instantaneous strength, and the cohesion decreased by approximately 30%. The slope foot unloaded and deformed owing to the excavation of a bauxite mine at its front edge, after which the slope deformed via creep. The landslide disaster occurred when the deformation was significantly accelerated and the slope started to slide as a whole once the sliding zone became water saturated owing to continuous rainfall. The simulation results indicate that the landslide can be divided into a front edge bulging zone, central sliding zone, and trailing edge tension zone, which provides valuable insight on the creep deformation evolution process and the disaster mechanism of the landslide under the action of front edge excavation and rainfall. Full article
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15 pages, 3227 KiB  
Communication
One-Dimensional Nonlinear Consolidation for Soft Clays with Continuous Drainage Boundary Considering Non-Darcy Flow
by Jin Wu, Ruichen Xi, Rongzhu Liang, Mengfan Zong and Wenbing Wu
Appl. Sci. 2023, 13(6), 3724; https://doi.org/10.3390/app13063724 - 15 Mar 2023
Cited by 3 | Viewed by 1027
Abstract
Adopting the non-Darcy flow presented by Hansbo and considering the nonlinear compression and permeability characteristics of soils, the one-dimensional nonlinear consolidation problem of soft clays is investigated by means of a continuous drainage boundary. The numerical solutions of average consolidation degrees defined by [...] Read more.
Adopting the non-Darcy flow presented by Hansbo and considering the nonlinear compression and permeability characteristics of soils, the one-dimensional nonlinear consolidation problem of soft clays is investigated by means of a continuous drainage boundary. The numerical solutions of average consolidation degrees defined by settlement and excess pore water pressure are derived by using the finite difference method, and the correctness of these solutions is verified by comparing them with existing analytical and numerical solutions. Based on the proposed solutions, a parametric study is conducted to study the influence of interface parameter, non-Darcy flow parameter and soil nonlinearity on the consolidation behavior of soft clays. The results show that the solutions based on the continuous drainage boundary can be degenerated into the solutions based on the Terzaghi drainage boundary if the interface parameter is taken as a reasonable value. The soil consolidation behavior considering both non-Darcy seepage and nonlinear characteristics of soil is very complex. Full article
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17 pages, 6921 KiB  
Article
Effect of Local Cyclic Loading on Direct Shear Strength Characteristics of Shear-Zone Soil
by Qiong Chen, Deshan Cui, Qingbing Liu and Xianyu Tao
Appl. Sci. 2022, 12(24), 13024; https://doi.org/10.3390/app122413024 - 19 Dec 2022
Viewed by 1472
Abstract
The reservoir landslide in the Three Gorges Reservoir Area (TGRA) often suffers from local cyclic loading scenarios produced by surge waves, groundwater level fluctuation, traffic loading, and seismic activity. However, the effects of local cyclic loading on the shear resistance of the shear-zone [...] Read more.
The reservoir landslide in the Three Gorges Reservoir Area (TGRA) often suffers from local cyclic loading scenarios produced by surge waves, groundwater level fluctuation, traffic loading, and seismic activity. However, the effects of local cyclic loading on the shear resistance of the shear-zone of the reservoir landslide are poorly understood. This study experimentally investigates the effects of local cyclic loading on the shear strength and the deformation of shear-zone material using cyclic direct shear tests. A series of cyclic direct shear tests are performed with different normal stresses, cyclic periods, and numbers of cycles. The experimental results indicate that: (1) Compared with monotonic loading, local cyclic loading can significantly decrease the shear stress of shear-zone soil. (2) Shear-zone soil exhibits greater volumetric contraction under local cyclic loading conditions than that under monotonic loading. (3) Under different vertical stresses, the differentiation of shear deformation after 40 cycles of loading was slight and virtually insignificant. The research results reveal the weakening law of the mechanical strength of shear-zone soil under local cyclic loading, which provides a foundation for investigating the mechanism of the reservoir landslide under the fluctuation of water levels. Full article
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21 pages, 10295 KiB  
Article
Enlarged Head Pressure-Dispersed Anchor Cable for Foundation Pit Engineering Purposes
by Chongfu Wu, Linghe Kong, Quanwei Guo and Haiying Cao
Appl. Sci. 2022, 12(23), 12400; https://doi.org/10.3390/app122312400 - 4 Dec 2022
Viewed by 1183
Abstract
The enlarged head pressure-dispersed anchor cable is a new type of anchor cable, and the enlarged head of the anchor solid is a multisegment body with variable cross section. Compared with the traditional tension type anchor cable structure, the stress mode of the [...] Read more.
The enlarged head pressure-dispersed anchor cable is a new type of anchor cable, and the enlarged head of the anchor solid is a multisegment body with variable cross section. Compared with the traditional tension type anchor cable structure, the stress mode of the anchor solid is changed from tensile stress to compressive stress, which is more reasonable. The development process of the plastic zone of the soil around the enlarged head anchor solid is verified by a simulation method. The spherical plastic zone space formed at the enlarged head anchorage end is conducive to the load transfer between the anchor solid and the surrounding soil and reduces the displacement of the anchor solid in the soil. In this pursuit, the present study examines the force mechanism of the enlarged head pressure-dispersed anchor cable. Subsequently, taking an actual project as an example, the anchoring capacity of the enlarged head pressure-dispersed anchor cable and enlarged head tension-type anchor cable was analyzed and compared using FLAC3D software. The results indicate that the support effect of the enlarged head pressure-dispersed anchor cable was better than that of the enlarged head tension anchor cable. Full article
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21 pages, 9918 KiB  
Article
Stability Conditions in Lignite Open Pits from Romania, Case Study: Oltețu Open Pit
by Maria Lazar, Florin Faur and Izabela-Maria Apostu
Appl. Sci. 2022, 12(19), 9607; https://doi.org/10.3390/app12199607 - 24 Sep 2022
Cited by 3 | Viewed by 1324
Abstract
The problem of the slope stability of open pit mines is one of constant interest and great importance, both during the period of operation, but also post-closure. The research focused on the Oltețu open pit (located in Berbesti Mining Basin, Romania) and was [...] Read more.
The problem of the slope stability of open pit mines is one of constant interest and great importance, both during the period of operation, but also post-closure. The research focused on the Oltețu open pit (located in Berbesti Mining Basin, Romania) and was directed in such a way as to allow consideration in the stability analyses of natural (predisposing the investigated area to landslides) and anthropogenic (specific to open pit mining) factors and causes as well as their combined effect. The field investigations (observations on the technical condition of the slopes, discussions with the technical personnel from Oltețu open pit, and sampling) were completed with analyses and laboratory tests (physical–mechanical properties of rocks in the composition of the slopes). The stability analyses took into account different hypotheses related to the actual geometry of the working slopes, and a predictive analysis was also carried out for the forecasted evolution of the working fronts and lateral slopes. Following stability analyses, it was found that for most slopes, the stability reserve is insufficient to allow continuing lignite exploitation under safe conditions. The last part of the paper presents the solutions identified by the authors (adoption of new geometries of the working front and lateral slopes) in order to increase the stability reserve to a minimum acceptable level, which would allow the safe continuation of lignite extraction, and, in the end, some practical recommendations are briefly presented. Full article
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23 pages, 8446 KiB  
Article
Probabilistic Analysis of Ground Surface Settlement of Excavation Considering Spatial Variable Modified Cam-Clay Model Parameters
by Hao Cheng, Hui Chen, Hanying Jia, Shu Zhang and Xiao Liu
Appl. Sci. 2022, 12(19), 9411; https://doi.org/10.3390/app12199411 - 20 Sep 2022
Cited by 1 | Viewed by 1518
Abstract
The modified Cam-clay model (MCC model) is capable of representing the consolidation process of the soil under a complex stress path and thus is extensively adopted in the numerical analysis of excavation engineering. For reliability problems of ground surface settlement of excavation, minimal [...] Read more.
The modified Cam-clay model (MCC model) is capable of representing the consolidation process of the soil under a complex stress path and thus is extensively adopted in the numerical analysis of excavation engineering. For reliability problems of ground surface settlement of excavation, minimal attention has been paid to investigating the effect of spatial variable MCC model parameters on the settlement during the staged construction of the excavation. Based on laboratory tests and sensitivity analysis, this study launched the probabilistic transient hydro-mechanical coupling analysis of excavation settlement considering spatial variable deformation parameters (λ and κ) using an MCS-FORM hybrid approach. The results show that: (1) Both the deformation parameters have a positive relationship with the settlement, and κ has a more significant effect than λ. (2) The observed maximum settlement and the location with maximum settlement follow a log-normal distribution. (3) An increasing COV of parameters leads to an enhanced surface settlement, expansion of the significant influence region, and decreased reliability. (4) The reliability index is greatly enhanced with the delimited controlled standard value of the surface settlement, Hcon, and it decreases significantly at the preliminary stage and then decreases progressively until stable during excavating. Overall, adopting the deterministic analysis without considering the spatial variability of MCC parameters leads to underestimating the risk due to the settlement and the significant influence region. Full article
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19 pages, 9180 KiB  
Article
Effect of Water Content Variation on the Tensile Characteristic of Clayey Loess in Ili Valley, China
by Penglin Zheng, Jinge Wang, Zihao Wu, Wei Huang, Changdong Li and Qingbing Liu
Appl. Sci. 2022, 12(17), 8470; https://doi.org/10.3390/app12178470 - 25 Aug 2022
Cited by 3 | Viewed by 1359
Abstract
The mechanical behavior of loess is highly predicated on variation in its moisture content. While the impacts of the water content on the shearing behavior and collapsibility of loess have been extensively studied, its effect on tensile characteristics has received relatively little attention. [...] Read more.
The mechanical behavior of loess is highly predicated on variation in its moisture content. While the impacts of the water content on the shearing behavior and collapsibility of loess have been extensively studied, its effect on tensile characteristics has received relatively little attention. In this study, a series of tensile tests were conducted on remolded specimens of a clayey loess that were collected from Ili Valley in China. Two sets of loess specimens with varying water contents were prepared separately using wetting and drying methods. The influence of the water content on the tensile stress–strain response, failure mode and tensile strength was investigated by combining the tensile test results and particle image velocimetry (PIV) analysis. On this basis, a nuclear magnetic resonance (NMR) test and scanning electron microscopy (SEM) observations were implemented in order to assist with the interpretation of the underlying mechanism. The test results indicate that the tensile failure process and the variation of tensile strength with varying water contents differ for specimens that are prepared with wetting and drying methods; a finding which arises from the differences in the soil microstructure, clay–water interaction and the distribution of capillary and adsorbed water. This research has shown that the tensile strength of clayey loess is essentially dominated by the clay’s hydration/cementation and the development of capillary and adsorption suction as well as the microstructural evolution that occurs with the change in the water content. Based on the experimental observations, a conceptual model is proposed in order to interpret the effect of water content on loess’ tensile behavior. Full article
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16 pages, 2986 KiB  
Article
An Investigation on Mineral Dissolution and Precipitation in Cement-Stabilized Soils: Thermodynamic Modeling and Experimental Analysis
by Enyue Ji, Fei Xu, Hua Wei, Wenxun Qian, Yang He and Pengfei Zhu
Appl. Sci. 2022, 12(14), 6843; https://doi.org/10.3390/app12146843 - 6 Jul 2022
Cited by 2 | Viewed by 1179
Abstract
Thermodynamic modeling helps to reveal insights into the basic chemical kinetics of dissolution and precipitation in cementitious materials, but relevant applications to cement-stabilized soils have seldom been reported. Based on the thermodynamic database of Cemdata18 and the pore solution composition of cement-stabilized soils, [...] Read more.
Thermodynamic modeling helps to reveal insights into the basic chemical kinetics of dissolution and precipitation in cementitious materials, but relevant applications to cement-stabilized soils have seldom been reported. Based on the thermodynamic database of Cemdata18 and the pore solution composition of cement-stabilized soils, this study formulated a specialized thermodynamic model, using essential thermodynamic constants for soil minerals that were calculated to ensure the model’s accuracy. Two commercial admixtures of alkaline activator and polynaphthalene sulfonate were selected for the different modification mechanisms and plain and modified cement-stabilized soils were prepared. Compressive strength was tested to determine the specimens for pore solution analysis and the influences of the admixture type and dose on dissolution and precipitation were investigated by modeling the ionic activity products and saturation indexes. An X-ray diffraction (XRD) analysis was performed to verify and complement the thermodynamic results. The major research findings were that (1) thermodynamic modeling can be reliably applied to cement-stabilized soils by providing the essential thermodynamic data and an appropriate product model, (2) the pozzolanic reaction is accelerated by increasing the OH concentration in the pore solution, while the cement hydration is highly dependent on the dissolution of Ca(OH)2 and the relevant complexes and (3) the dissolution equilibrium of Ca(OH)2 is directly affected by the alkaline activator dissolution and is indirectly affected by the polynaphthalene sulfonate adsorption of the reactants. Full article
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17 pages, 5360 KiB  
Article
Development of a Model Material for Dynamic Geotechnical Model Tests
by Jianlin Tian, Liangqing Wang, Cailong An, Qiong Wu, Zihao Sun and Rui Ke
Appl. Sci. 2022, 12(11), 5344; https://doi.org/10.3390/app12115344 - 25 May 2022
Cited by 2 | Viewed by 1065
Abstract
To develop a model material suitable for analysing the stability of sandstone slopes during strong earthquakes, an orthogonal test was designed by selecting seven physico-mechemical parameters, a combination of dynamic and static parameters, as research indexes. Then, the influence of the proportion of [...] Read more.
To develop a model material suitable for analysing the stability of sandstone slopes during strong earthquakes, an orthogonal test was designed by selecting seven physico-mechemical parameters, a combination of dynamic and static parameters, as research indexes. Then, the influence of the proportion of each component in the model material on each test index was determined by sensitivity analysis, and the quantitative relationship between physico-mechanical parameters and component proportions was established by multiple linear regression analysis to develop a model material similar to sandstone. Finally, a sandstone slope along the Duxiang Expressway was taken as an example, and the proportions of the components suitable for a model of the rock mass in this area were determined. The test results showed that (1) the physico-mechanical parameters selected for the dynamic and static tests were used to effectively develop model materials for dynamic geotechnical model tests; (2) samples of model materials composed of barite powder, quartz sand, ferric powder, gypsum and cement met the requirements for dynamic testing of geotechnical models of sandstone slopes; and (3) through sensitivity analysis of various factors and multiple linear regression analysis, the required model materials were efficiently configured, and the failure mode, failure process and physico-mechanical parameters of the model materials accurately simulated the original rock materials. Full article
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23 pages, 13694 KiB  
Article
Estimating the Optimal Overall Slope Angle of Open-Pit Mines with Probabilistic Analysis
by Wael R. Abdellah, Chiaki Hirohama, Atsushi Sainoki, Ahmed Rushdy Towfeek and Mahrous A. M. Ali
Appl. Sci. 2022, 12(9), 4746; https://doi.org/10.3390/app12094746 - 9 May 2022
Cited by 2 | Viewed by 4949
Abstract
Slope instability of open-pit mines has adverse impacts on the overall mine profitability, safety and environment. The slope of an open-pit mine is crucially influenced by the slope geometry, quality of rock mass and presence of geological features and their properties. The objective [...] Read more.
Slope instability of open-pit mines has adverse impacts on the overall mine profitability, safety and environment. The slope of an open-pit mine is crucially influenced by the slope geometry, quality of rock mass and presence of geological features and their properties. The objective of this study is to demonstrate a method to select the optimal overall slope angle of open-pit mines according to three design parameters, namely, safety (e.g., probability of instability), productivity (e.g., profit) and mining costs (e.g., cost of removal of overburden). Therefore, this study attempts a hybrid approach in which numerical modelling is integrated with probabilistic analysis to evaluate the stability of an open-pit mine at various overall slope angles. Two-dimensional elasto-plastic finite-element, RS2D, has been used to develop a series of models at different ultimate slope angles employing shear strength reduction technique (SSRT). Li’s point-estimate method of n3 has been invoked in deterministic analysis to tackle the inherent uncertainty associated with host rock mass properties. The results reveal that the mine profitability increases and the cost of overburden removal decreases as overall slope angle becomes steeper. However, the slope stability deteriorates. Therefore, it is highly advisable to combine these three design parameters (e.g., safety, productivity, and cost) together when selecting overall slope angle of open-pit mines. Full article
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21 pages, 32044 KiB  
Article
Changes of Physical and Mechanical Properties of Coral Reef Limestone under CO2–Seawater–Rock Interaction
by Yu Zhong, Qi Li, Ren Wang and Ting Yao
Appl. Sci. 2022, 12(9), 4105; https://doi.org/10.3390/app12094105 - 19 Apr 2022
Cited by 6 | Viewed by 2105
Abstract
Large amounts of anthropogenic CO2 in the atmosphere are taken up when the ocean alters the seawater carbonate system, which could have a significant impact on carbonate-rich sediments. Coral reef limestone is a special biogenic carbonate, which is mainly composed of calcium [...] Read more.
Large amounts of anthropogenic CO2 in the atmosphere are taken up when the ocean alters the seawater carbonate system, which could have a significant impact on carbonate-rich sediments. Coral reef limestone is a special biogenic carbonate, which is mainly composed of calcium carbonate. When carbonate-rich rocks are brought into contact with a CO2 weak acid solution, they will be dissolved, which may affect the physical and mechanical properties of the rock. In this paper, the physical and chemical interactions between CO2, seawater and the framework structure reef limestone were studied based on an experiment conducted in a hydrothermal reactor. The solution was analyzed for dissolved Ca2+ concentration during the reaction, and the rock mass, effective volume (except for the volume of open pores), permeability, images from electron microscopy and X-ray microtomography were contrasted before and after immersion. The uniaxial compressive and tensile strength tests were conducted, respectively, to clarify the mechanical response of the rock after the reaction. The results indicate that dissolution occurred during the reaction, and the calcium ions of the solution were increased. The physical properties of the rock were changed, and the permeability significantly increased. Because the rocks were soaked for only 15 days, the total cumulative amount of calcium carbonate dissolved was less, and the mechanical properties were not affected. Full article
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22 pages, 7189 KiB  
Article
Analysis of Shear Constitutive Models of the Slip Zone Soil Based on Various Statistical Damage Distributions
by Yinfeng Luo, Zongxing Zou, Changdong Li, Haojie Duan, Nang Mon Mon Thaw, Bocheng Zhang, Bingdong Ding and Junrong Zhang
Appl. Sci. 2022, 12(7), 3493; https://doi.org/10.3390/app12073493 - 30 Mar 2022
Cited by 3 | Viewed by 1711
Abstract
The shear constitutive model of the slip zone soil can be used to quantitatively describe the relationship between shear stress and shear displacement, which is of great significance for the analysis of deformation mechanism and stability evaluation of landslides. The conventional shear constitutive [...] Read more.
The shear constitutive model of the slip zone soil can be used to quantitatively describe the relationship between shear stress and shear displacement, which is of great significance for the analysis of deformation mechanism and stability evaluation of landslides. The conventional shear constitutive models were usually proposed based on statistical damage theory with the Weibull distribution function, which is widely used in the field of rock material. However, there are great differences in the structure and mechanical properties of soil and rock; therefore, the suitability of the damage distribution functions for the slip zone soil needs to be further investigated. In this study, eight distribution functions are introduced to describe the damage evolution process of the slip zone soil and applied to two groups of shear stress–shear displacement curves (named shear curves) with different softening characteristics, i.e., strong softening type and weak softening type. The results show that: (1) the applicability of the various damage distribution functions to the two softening types of shear curves is obviously different; (2) the commonly used Weibull distribution is only suitable for the weak softening shear curves; (3) the shear constitutive models based on Gamma, Exponential, and Logistic distributions are the best three models for the strong softening curve; the shear constitutive models based on Gamma, Weibull, and Exponential distributions are the best three models for the weak softening curve; (4) Gamma distribution function is the optimal model in both strong softening and weak softening types of shear curves, and the parameters of the function have clear physical meaning in the shear constitutive model. In general, the Gamma distribution function can more objectively reflect the whole shear damage evolution process of the slip zone soil than other distribution functions. Full article
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22 pages, 7365 KiB  
Article
An Efficient Parallel Framework for the Discrete Element Method Using GPU
by Youkou Dong, Dingtao Yan and Lan Cui
Appl. Sci. 2022, 12(6), 3107; https://doi.org/10.3390/app12063107 - 18 Mar 2022
Cited by 2 | Viewed by 1702
Abstract
The discrete element method (DEM), a discontinuum-based method to simulate the interaction between neighbouring particles of granular materials, suffers from intensive computational workload caused by massive particle numbers, irregular particle shapes, and complicated interaction modes from the meso-scale representation of the macro information. [...] Read more.
The discrete element method (DEM), a discontinuum-based method to simulate the interaction between neighbouring particles of granular materials, suffers from intensive computational workload caused by massive particle numbers, irregular particle shapes, and complicated interaction modes from the meso-scale representation of the macro information. To promote the efficiency of the DEM and enlarge the modelling scales with a higher realism of the particle shapes, parallel computing on the graphics processing unit (GPU) is developed in this paper. The potential data race between the computing cores in the parallelisation is tackled by establishing the contact pair list with a hybrid technique. All the computations in the DEM are made on the GPU cores. Three benchmark cases, a triaxial test of a sand specimen, cone penetration test and granular flow due to a dam break, are used to evaluate the performance of the GPU parallel strategy. Acceleration of the GPU parallel simulations over the conventional CPU sequential counterparts is quantified in terms of speedup. The average speedups with the GPU parallelisation are 84, 73, and 60 for the benchmark cases. Full article
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