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The slope stability analysis and support structure design of temporary roads are particularly important for the normal traffic of roads and the safe construction of underground structures. In this paper, FLAC3D software is used to study the numerical simulation of steel pipe piles support structure of the slope of temporary road by using the equivalent stiffness method. It is shown that under the action of road load, the normal stress of steel pipe pile has a peak value at 1.0m above the bottom of foundation pit, and the shear stress has two peaks at 1.0m above the bottom of foundation pit and 0.5m above the pile tip, which decrease at the pile tip. The horizontal displacement of the pile occurs at different depth, the displacement of the pile top is the largest, and the displacement from the pile top to the bottom of foundation pit decreases nonlinearly, and the horizontal displacement of the pile below the bottom of foundation pit is very small and remains unchanged. The vertical displacement of the pile increases gradually from the pile top to the pile tip, which results in tensile deformation of the pile. Stress concentration occurs at the temporary road position in the slope, and obvious horizontal displacement and vertical displacement which have obvious differences in different positions appear in the slope. The arrangement of piles can ensure the stability of the slope and there will be no overall shear failure surface. [ABSTRACT FROM AUTHOR]

This paper took the Fengmaoding slope, typically found in the mountainous areas of central Shanxi province, as its research area. The stratum structure of the Fengmaoding slope is a typical coal measures stratum covered by a layer of loess. There are communication towers on the slope mass and top of the slope; railways, roads, and rivers at the foot of the slope. There are many villages across from the slope, therefore, the buildings and structures nearby, even the lives of the villagers are threatened by the damages caused by the deformation of the slope. Tectonic development and mining activities have very profound effects on the stability of the slope. Considering the above, this paper analyzed the effects of the fault in controlling the deformation features of the destabilized slope during underground mining by adopting the method of numerical simulation from these perspectives including displacement, stress, strain, among others. under different circumstances (the faulted and unfaulted) so as to provide guidance for future studies about landslides of the same type and give preventive proposals for reference. [ABSTRACT FROM AUTHOR]

Deterministic seismic slope stability design charts for cohesive–frictional (--> c – ϕ -->) soils are traditionally used by geotechnical engineers to include the effects of earthquakes on slopes. These charts identify the critical seismic load event that is sufficient to bring the slope to a state of limit equilibrium, but they do not specify the probability of this event. In this paper, the probabilistic seismic stability of slopes, modeled using a two-dimensional spatially random --> c – ϕ --> soil, is examined for the first time using the random finite element method (RFEM). Slope stability design aids for seismic loading, which consider spatial variability of the soil, are provided to allow informed geotechnical seismic design decisions in the face of geotechnical uncertainties. The paper also provides estimates of the probability of slope failure without requiring computer simulations. How the design aids may be used is demonstrated with an example of slope remediation cost analysis and risk-based design. [ABSTRACT FROM AUTHOR]

The paper describes the recent devastating landslide of Kotrupi, Himachal Pradesh in India which had claimed many human lives and properties along its course on 13 August 2017. This event was the third reactivation of the slide as per data available. The study for this landslide involves a preliminary investigation of the site and comparison of pre- and post-event slope stability analysis. Other than rainfall, the combined effect of differential weathering rate of the debris and soil layers, low material strength, and the presence of a fault zone was found to be the primary cause of instability. The analysis was carried out with the geotechnical investigation and numerical modeling with the help of finite element model-based Phase 2 simulator. The significant findings of this paper include numerical simulation of pre- and post-event slide as stated under unsaturated and saturated condition. The study finds a low factor of safety of the present slope. The unstable condition of the slope may trigger another event of the same intensity shortly. [ABSTRACT FROM AUTHOR]

In this paper, the slope of the open pit of Dahongshan iron ore mine in Yunnan is taken as the research object, the safety coefficient and settlement values of the slope under natural and rainfall conditions are derived by the finite element software Midas/GTS, and the surface settlement versus time is produced by fusing the InSAR monitoring results of the study area for a whole year to judge the stability of the open pit slope. The results show that the settlement and deformation areas shown by numerical simulation and InSAR monitoring results are consistent; the comparison between InSAR monitoring results and rainfall intensity shows that the cumulative value of slope settlement has a high correlation with heavy rainfall. The safety coefficients of the slopes of the open pit under natural conditions and rainfall conditions are 1.50 and 1.21, the cumulative value of settlement in InSAR monitoring data for one year is 18.4 mm, and no obvious large deformation area is found. The use of numerical simulation combined with InSAR monitoring can realize the analysis of the stability of the slope of the open pit mine. [ABSTRACT FROM AUTHOR]

This study explores the pile-soil interaction mechanism and the optimal use of antislide piles for slope reinforcement based on finite difference numerical modelling. The force and displacement principles of slopes and antislide piles are analysed. The influences of various factors are investigated, such as postpile filling parameters, pile embedding methods, and pile cross-sectional shapes. Numerical modelling is used to determine the optimal layouts of antislide piles for push and traction landslides. The findings indicate that the cohesive force of the fill has a greater influence on the piles and slope than the friction angle and is the primary control factor. Fully buried antislide piles provide a better antisliding effect than semiburied ones. With fully buried piles, the best controlling effect is obtained when the ratio of the length of the pile's free section to the height of the sliding body is approximately 4/5. Moreover, stepped-cross-section piles provide better slope reinforcement than those with rectangular, T-shaped, or trapezoidal cross-sections. In practical applications, end-bearing arches can be utilized as the primary control structures, with friction arches used for secondary control to improve the soil arching effect as much as possible, thereby enhancing the stability of the piles and slope. To control landslides of various thrust forms, antislide piles should be set in the active section, the core sliding section, or both, as required. This paper provides guidance for improving the design of antislide piles. [ABSTRACT FROM AUTHOR]

Root reinforcement is an interesting and environmentally favorable measure for soil stabilization. When properly applied, it can improve soil strength significantly. The paper presents a simulation of a series of drained triaxial tests on soil samples with different levels of root reinforcement in a form of three 5-mm-thick layers, located on different heights. Modified Cam-clay extended for unsaturated soils containing plant roots is used in calculations. The tests are modeled numerically and the results are compared with experimental results from the literature. Missing soil and root parameters are obtained based on the model calibration and further applied in the calculations of the stability of the vegetated slope subjected to rainfall. The influence of the initial root mass in the reinforcing superficial soil layer on the time after which a landslide occurs is investigated. The results suggest that even a minor level of root reinforcement may postpone the development of a rainfall-induced landslide. [ABSTRACT FROM AUTHOR]

Detailed surface topography is important when analyzing the stability of slopes. Recent advances in new technologies such as interferometric synthetic aperture radar and light detection and ranging have allowed us to obtain high-precision profiles of distant landscapes and objects including detailed slope information for three-dimensional (3D) slope stability analysis. However, techniques of reconstructing 3D numerical models from scanned data of slope geometry have not been well investigated or tested. This paper proposes a comprehensive approach that integrates laser scanning and finite element method for slope stability analysis, particularly failure prediction under precipitation scenarios. The methodology is applied to a slope in the Wenchuan earthquake-stricken mountainous region that failed in 2013, triggered by severe rainfall. The modelling results show that the surface sampling resolution can affect the prediction accuracy of the potential failure zones. When constructing the slope model, the selected surface grid should be fine enough to capture the important topographic features of the slope while minimizing computation demand. This paper confirms that the proposed method can be successfully used to identify the potential failure zones of the investigated slope under severe rainfall conditions. [ABSTRACT FROM AUTHOR]

The optimization design of the open pit slope can ensure safety in production at the same time bring considerable economic benefits, so it is necessary to evaluate the stability of the initial excavation scheme of the high slope in an open-pit mine and optimize the initial slope angle according to the evaluation results. In this paper, an exhaustive study of Anyi open-pit mine in mouding County Yunnan province China has been made, and the following results have been achieved: (1)Confirmed the geological factors which affected the slope stability of open-pit mine; (2)Quantified the stability of the open-pit mine slope; (3) Under the premise of safety, the angle of the open pit high slope has been optimized on the base of the calculations of the open-pit mine high slope stability so as to ensure the maximum economic benefit. In this paper, the study area was divided into six zones. Firstly, qualitative analysis of slope stability was made by analogy method of engineering geology and stereographic projection method according to the orebody location, the properties of rock and soil in slope, the height of slope, and so on. The analysis shows that the preliminary design of slope angle is so large to ensure safety. Secondly, the stability of different slopes of a high slope is the quantitative analysis of different zones in high slope was made by two-dimensional limit equilibrium method and the finite difference method. In this paper, the mechanical parameters of rock are obtained by a laboratory test, and the stability of the high slope is quantitatively analyzed by two-dimensional limit equilibrium and three-dimensional numerical simulation. • Confirmed the geological factors which affected the slope stability. • Quantified the stability of the open-pit mine slope. • Under the premise of safety, the angle of the open pit high slope. • The preliminary design of slope angle is so large to ensure safety. [ABSTRACT FROM AUTHOR]

The geotechnical assessment, safe design and monitoring of highwalls is one of the major challenges in Indian open pit mines. The aim of opencast mines should be to attain steepest possible slope angle without compromising safety in order to maximize profits. Highwall stability is essential for economical and safe exploitation of mineral during open pit mining. Geotechnical investigations are required to quantify the properties of soils and rocks within the mining horizons. The required minimum safety factor for highwalls is 1.2. Highwall should be monitored during open pit operations. This paper addresses the main elements of pit slope failure, accident statistics, design, and monitoring and pit slope management and also the guidelines for safe design and monitoring of open pit highwalls in India. [ABSTRACT FROM AUTHOR]

Summary: This paper reappraises Perzyna‐type viscoplasticity for the constitutive modelling of granular geomaterials, with emphasis on the simulation of rate/time effects of different magnitude. An existing elasto‐plastic model for sands is first recast into a Perzyna viscoplastic formulation and then calibrated/validated against laboratory test results on Hostun sand from the literature. Notable model features include (1) enhanced definition of the viscous nucleus function and (2) void ratio dependence of stiffness and viscous parameters, to model the pycnotropic behaviour of granular materials with a single set of parameters, uniquely identified against standard creep and triaxial test results. The comparison between experimental data and numerical simulations points out the predicative capability of the developed model and the complexity of defining a unique viscous nucleus function to capture sand behaviour under different loading/initial/boundary and drainage conditions. It is concluded that the unified viscoplastic simulation of both drained and undrained response is particularly challenging within Perzyna's framework and opens to future research in the area. The discussion presented is relevant, for instance, to the simulation of multiphase strain localisation phenomena, such as those associated to slope stability problems in variably saturated soils. [ABSTRACT FROM AUTHOR]

Abstract The present paper describes the design of a comprehensive rainfall simulator which is particularly meant for the assessment of soil erosion at plot scale by considering various soil grain types, soil slope angles, and surface exposures under different rainfall conditions. The entire setup is divided into four major parts: (a) water supply system with single spray nozzle, (b) supporting metal frame, (c) hydraulic jack attached container table for slope adjustment, and (d) temperature simulator. It covers an area of 3 m2, out of which 0.5 m2 is the target area or experimental plot and the simulated raindrops fall from a height of 2.3 m. Four types of full-jet spray nozzles are used to simulate rainfall intensities of 65, 93, 112, and 148 mm/h. The experimental plot can attain a maximum slope angle of 40° using a hydraulic jack unit. A temperature simulator is designed to replicate the natural conditions in the laboratory. Physical and numerical simulations are carried out to measure the characteristics of simulated rainfall and compare with those of natural rainfall conditions. The Christiansen coefficient (Cu) of the designed rainfall simulator varies from 81 % to 88 %. The rain droplet size ranges from roughly 1 mm to 5 mm and their corresponding terminal velocities range from 4.76 m/s to 10.64 m/s, striking velocities are found between 5.56 m/s and 9.63 m/s, and kinetic energies ranging from 0.0081 mJ to 3.0342 mJ. The total kinetic energy of the raindrops striking the soil surface in the entire plot area of 0.5 m2 depends on the rainfall intensity and varies from about 6 J to 12 J. The designed setup is capable of simulating rainfall inside the laboratory with properties very close to those of natural rainfall. We adopt the Taguchi fractional factorial design of experiments to investigate the effects of different factors on soil erosion. Furthermore, statistical analysis of the experimental data is carried out by using signal-to-noise (S / N) ratio and the optimum condition for maximum soil erosion is predicted. The main objectives of this study are to design a comprehensive rainfall simulator setup, evaluate the properties of the simulated rainfall, provide a theoretical model and assess the several factors affecting soil erosion using reduced number of experiments in the laboratory. Highlights • A rainfall simulator is designed for soil erosion experiments in the laboratory. • Four full cone spray nozzles were used to simulate different rainfall intensities. • A temperature simulator is used to replicate natural conditions. • Theoretical explanations and simulations of rainfall properties are carried out. • Taguchi optimization is used to determine optimum condition for maximum soil erosion. [ABSTRACT FROM AUTHOR]

In this paper, we propose a new numerical approach abbreviated as Cos-SDA for analyzing strain localization problems of geomaterials. The Cos-SDA is achieved by implanting the strong discontinuity approach (SDA) into the computational framework of the Cosserat continuum finite element approach (Cos-FEA). Through two numerical examples of plane strain compression test and slope stability, it is demonstrated that the Cos-SDA model can effectively simulate the entire progressive failure process of geomaterials from weak discontinuity to strong discontinuity. Cos-SDA can effectively alleviate the influence of mesh distortion in shear zone, and the numerical solution can still maintain convergence even under large deformation. Cos-FEA and Cos-SDA have much stiffer mechanical response than SDA-FEA since an internal length scale is introduced into the governing equations. In contrast, the SDA-FEA shows more conservative as the unmature bifurcation occurs and weak discontinuous stage is ignored in the numerical simulation, while Cos-FEA numerical results show an over-stiff mechanical response in the stage of post failure. Cos-SDA inherits the advantages of both SDA-FEA and Cos-FEA and neutralizes their mechanical responses, so it is more reasonable in simulating the progressive failure process from weak discontinuity deformation (strain localization) to strong discontinuity deformation (slip) occurring in geomaerials. [ABSTRACT FROM AUTHOR]

The fluctuations of reservoir water levels significantly change the hydrogeological conditions of reservoir banks and thus affect the steady state of the bank slope. Reservoir landslide stability is governed by the complex interactions between the rock and the water (both reservoir and pore water). This paper establishes the constitutive coupled model of seepage and stress field for the E20 bank slope in the Haizhou Open Pit Coal Mine hydropower station's lower reservoir. Using the geotechnical engineering three-dimensional fast Lagrangian analysis of continua (FLAC-3D 4.0) program as a computational analysis tool, the E20 bank slope deformation mechanism was analyzed. The simulation model, calculated by using the Boit consolidation and pore-water continuity principles, was built using FEMs. The numerical simulation results showed that cyclical fluctuations and speeds of the reservoir's water level affect its bank slope stability. When the water level drops at a speed of 12 m/day, the simulation's calculated safety factor value is 0.99, but when the water level rises at a speed of 12 m/day, the calculated safety factor value is 1.03. The results demonstrated that the rapid drop of the water level had a greater impact on the reservoir bank slope stability than the rapid rise of the water level under the same conditions. [ABSTRACT FROM AUTHOR]

Predicted performance of a complex geotechnical system is subject to errors due to the uncertainties associated with both the prediction model and the system parameters. This paper aims to develop a multi-step updating method to reduce the uncertainties of the prediction model and system parameters using incremental time-series monitoring data, and to enhance the prediction of the future performance of the complex geotechnical system. The multi-step updating method considers inherent uncertainty of the system, model uncertainty and measurement uncertainty. The prediction is updated and improved step by step with new monitoring information using Bayes’ theorem. Two realistic geotechnical cases including a basement excavation and a multi-stage excavation of a high rock slope are presented for illustration. The multi-step updating method integrates the theoretical computational model with observational evidence. With more monitoring information being incorporated, the prediction becomes closer to the actual performance of the system, and the distributions of the system parameters become closer to the reality. [ABSTRACT FROM AUTHOR]

A slope stability analysis method using the finite element method and the limit equilibrium principle is presented in this paper to determine the critical slip surface and to calculate the minimum safety factor based on the stress field produced by a numerical simulation. This method assumes a cutting export and makes good use of geometric combination to reduce the search range during the calculation process. The proposed method was validated using two classical benchmark slopes and an engineering slope; it was also compared with other conventional limit equilibrium methods. The error between the proposed method and the limit equilibrium method was relatively small. The proposed method resolved several limitations of the traditional methods, and a comparison of the benchmark slopes showed that the proposed method exhibited good accuracy and efficiency. The proposed method can thus analyse both the stability of a natural slope and the stability of a soil slope under seismic loading conditions. [ABSTRACT FROM AUTHOR]

This paper investigates the performance of flexible culverts – often referred to as soil–steel composite bridges (SSCB) – when constructed in sloping topography. A number of 2D finite element models were created to simulate three case studies compromising two pipe arches and one high profile arch. The models were generated to investigate the effect of different surface slopes for different depths of soil cover. The aim was to understand and perceive the change of sectional forces in the structure with respect to slope increase under different soil covers. In addition, the effect of structure presence in the soil was also investigated in terms of soil stability. The results enable to realize the susceptibility of such structures to low heights of soil cover when built in sloping environment, which is seen in the incremental change in displacements and sectional forces, specially the bending moments. It is also found that the geometrical aspects of the profile shapes have more pronounced effect on their performance when introducing steeper slopes. The safety factor of soil stability is found to decrease when introducing such structures in the soil. [ABSTRACT FROM AUTHOR]

Recent 1- g shake table experiments have shown that the relatively new X-shaped cast-in-place piles can improve the seismic response of slopes susceptible to lateral-spreading as compared to conventional bored piles when mitigated using the pile-pinning method. This paper presents three-dimensional (3D) nonlinear dynamic numerical simulations of groups of piles with X-shaped cross-sections subjected to lateral spreading to broaden the understanding of their effectiveness in mitigating slope displacements. The unit cell method is used with the stress-ratio controlled and critical state-compatible Dafalias-Manzari model to capture appropriate cyclic behavior of the liquefiable soil surrounding the piles subjected to seismic ground motions. The numerical simulations facilitate the evaluation of various parameters controlling soil-pile interaction and the structural pile response, including the effect of pile spacing, pile fixity, pile orientation, slope angle, and geometrical effects of the pile cross-section with emphasis on the X-shaped section. The results demonstrate that X-shaped pile groups can significantly reduce lateral slope displacements compared to the unimproved or circular pile-improved ground, and that the spacing, pile orientation and pile fixity play a critical role in the deformation response. These findings provide insight to the design of pile-improved ground as well as the structural design of piling adjacent to or within liquefiable slopes. • The unit cell method is used with Dafalias-Manzari model to capture cyclic behavior of the liquefiable soil. • Various parameters controlling soil-pile interaction and the structural pile response are investigated. • X-shaped pile groups can significantly reduce the lateral slope displacements compared to the unimproved ground. • The pile spacing, pile orientation and pile fixity play a critical role in the deformation response. [ABSTRACT FROM AUTHOR]