Sudden and unforeseen seismic failures of coal mine overburden (OB) dump slopes interrupt mining operations, cause loss of lives and delay the production of coal. Consideration of the spatial heterogeneity of OB dump materials is imperative for an adequate evaluation of the seismic stability of OB dump slopes. In this study, pseudo-static seismic stability analyses are carried out for an OB dump slope by considering the material parameters obtained from an in-situ field investigation. Spatial heterogeneity is simulated through use of the random finite element method (RFEM) and the random limit equilibrium method (RLEM) and a comparative study is presented. Combinations of horizontal and vertical spatial correlation lengths were considered for simulating isotropic and anisotropic random fields within the OB dump slope. Seismic performances of the slope have been reported through the probability of failure and reliability index. It was observed that the RLEM approach overestimates failure probability (Pf) by considering seismic stability with spatial heterogeneity. The Pf was observed to increase with an increase in the coefficient of variation of friction angle of the dump materials. Further, it was inferred that the RLEM approach may not be adequately applicable for assessing the seismic stability of an OB dump slope for a horizontal seismic coefficient that is more than or equal to 0.1.

The metropolitan region of Belo Horizonte city is home to several high-risk areas with a significant number of mass movement occurrences. Additionally, there are cases of movements in areas that are not considered high-risk, where constructions exhibit a medium to high construction standard. This emphasizes that, in addition to disordered occupations, the terrains have a natural susceptibility to the process. Intervention in slopes through cuts and fills is an unquestionable necessity in geotechnical projects to reinforce unstable or damaged areas. This article explores the field of soil nailing and presents the necessary design practices for its utilization, including safety checks based on deterministic, probabilistic, and finite element analysis. The case study is based in Belo Horizonte, more specifically in the 'Buritis' neighborhood, Brazil. The reinforced slope has a height of 18.5 meters and covers a total area of 1425 square meters. Based on different methodologies, the solution was validated as the most technically feasible, executable, and financially viable.

This study aimed to emphasize the significance of spatial variability in soil strength parameters on the behavior of nailed walls, highlighting the necessity of probabilistic design approaches. The investigation involved a 7.2-m nailed wall reinforced with five nails, simulated using the local average subdivision random field theory combined with the limit equilibrium method and the FEM, known as the random limit equilibrium method (RLEM) and the random finite-element method (RFEM) approaches. Initially, the wall stability was evaluated by RLEM using 10,000 Latin hypercube sampling realizations. The wall was globally stable among all samples for a correlation length equal to its height (7.2 m). The wall behavior, associated displacements, moments, wall shear forces, nail axial forces, and ground settlements were examined using RFEM. The RFEM analysis reveals that different random fields influence the maximum displacement (H-max), maximum moment (M-max), and maximum shear force (Vmax) experienced by the wall. The cumulative distribution function plots were generated for the wall critical parameters, including H-max, M-max, and V-max. Leveraging the simple weighted averaging and ordered weighted averaging techniques, different combinations of H-max, M-max, and Vmax were assessed with varying weight assumptions. This allowed us to identify critical random field realizations and estimate the level of risk using a newly introduced parameter, the decision index. Finally, the effect of different correlation lengths (isotropic and anisotropic) for two different coefficients of variation of soil strength parameters on the distribution of H-max, M-max, and Vmax was studied. The findings highlight the importance of considering the spatial variability of soil properties to achieve a reliable design of nailed walls.

The presence of oil contamination causes changes in mechanical properties of clayey soil trenches with low liquid limits (CL) such as stress-strain behavior, rupture plain position, plastic zone, and strain energy for soil trenches compared with uncontaminated soils. These changes usually lead to a lower factor of safety against failure and expansion of the plastic zone. The effects of crude oil contamination on the soil shear strength were evaluated by direct shear and plate load tests for various clays and sandy soils. In this research, a numerical finite element modeling in ABAQUS software was used to estimate the effect of oil contamination in the range of 0 to 16% (0%-4%-8%-12%-16%) on the stability safety factor of vertical clayey trenches with heights of 3 m, 4 m, 5 m, and 6 m, and the results were compared with results of a limit state analysis. The findings of the limit equilibrium method show that adding 4% of oil contamination to a clayey trench will decrease 62% of its critical depth. Also, the numerical analysis results show that adding oil contamination in the range of 0 to 16% to the clayey soil will increase the maximum displacements of the trenches to five times their clean state.

Ensuring construction safety and promoting environmental conservation, necessitate the determination of the optimal jacking force for rectangular pipe jacking projects. However, reliance on empirical calculations for estimating jacking force often resulted in overly conservative results. This study proposed a modified Protodyakonov ' s arch model to calculate the soil pressure around the jacked pipe considering the critical damage boundary. A three-dimensional log-spiral prism model, based on limit equilibrium method was applied to analyze the resistance on the shield face. The determination of jacking force integrated factors such as soil pressure around jacked pipes, friction coefficient between pipe and soil, and shield face resistance. By utilizing Suzhou ' s jacking-pipe engineering as a practical context, the accuracy was validated against field monitoring data and existing jacking force calculation models of varying specifications. Parametric analysis indicated the jacking force is linearly correlated with the soil unit weight and pipe-soil friction coefficient. However, the jacking force decreases significantly with increasing internal friction angle. As the internal friction angle rose from 25 degrees to 50 degrees , the soil arch height gradually diminished from 8.91 to 2.59 m. Notably, a complete arch structure failed to form above the jacked pipe when the cover depth ratio was less than 0.5. The heightened predictive precision of the proposed model enhanced its suitability for practical shallow buried tunnel jacking force predictions.

Three-dimensional slope stability study is preferable to 2D stability assessments since all slopes are three-dimensional. Based on 3D extensions of the ordinary slice method and simplified Bishop's method, this study presents 3D slope stability analysis results for homogenous and heterogeneous soil slopes. The geometry of the slope is built with the help of the Digital Elevation Modelling (DEM) technique. Both the ordinary column method (OCM) and simplified Bishop's method (SBM) in 3D satisfy the moment equilibrium of the failure mass. The obtained FS values for all three problems match the published results closely. The effects of pore water pressure applications and seismic loadings are further investigated by considering different combinations. The pore pressure ratio (ru) and horizontal seismic coefficient (keq), with values ranging from 0.25 to 0.50 and 0.05 to 0.10, respectively, have been considered in the present analysis. The detailed variations of normal and shear forces acting on the base of the 3D columns, as well as the variations of other important parameters such as true dip angle and apparent dip angles along the longitudinal and lateral direction of the failure surface, are shown to highlight the mechanisms of generation of internal forces inside the failure mass, both along longitudinal and lateral directions of the slope. The plots of normal and shear forces along the longitudinal direction of the slope follow a symmetric distribution. In contrast, these plots along the lateral direction of the slope follow an asymmetric profile. It is further seen that when pore pressure and earthquake forces are considered, the normal forces increase, and the mobilised shear forces decrease along both longitudinal and lateral directions of the 3D slope.

This paper employs Discrete Element Method (DEM) simulations to investigate the influence of relative density on soil arching within a plane -strain active trapdoor scenario. For varying relative trapdoor depths, DEM simulations illustrate the key influence of dilatancy on displacement and strain fields and on stress rotation and trapdoor pressure, confirming that shear bands develop at the trapdoor depending on the soil's dilation angle. The interplay between dilatancy and soil cover governs the arching phenomenon and the ground deformation mode; the significance of relative density is also highlighted by its effects on the principal stress rotation and ground reaction curves. To predict the minimum trapdoor pressure, we propose a Limit Equilibrium Method (LEM) solution that considers the type of failure mechanism (trapezoidal or triangular) and the lateral earth pressure as a function of the soil's dilatancy and stress arching shape; this approach coincides with Terzaghi's soil pressure concept at the critical state. LEM predictions of minimum and ultimate (or terminal) trapdoor pressure, and of shear deformation modes, are validated with our DEM results and with literature results. Finally, the impact of effective stresses and relative density on deformation patterns and design charts that quantify the minimum trapdoor pressure is discussed.

Too little support force at the palm surface during shield excavation can lead to destabilization of soil before the excavation face and cause ground subsidence. Construction disturbances during excavation can affect the mechanical properties of the surrounding soil, which cannot be ignored when determining the needed support force at an excavation face. Based on the Mohr - Coulomb yield criterion, the collapse of dense sandy soils before the excavation face of shallowly buried shield tunnels is simulated using PLAXIS 3D to determine the collapse mode. Furthermore, the prismatic body in the traditional 3D wedge model is modified to an inverted elliptical-truncated cone with a certain inclination so that the collapse zone is closer to real sliding soils, and the disturbance ratio r is introduced as an index to consider a construction disturbance. The expression of the active limit support force with respect to wedge inclination is derived, and the maximum support force is determined by trial and error to be the minimum support force needed. The results of the modified 3D curved model are in good agreement with the numerical simulation results, as well as the results of theoretical methods and model tests.

Toppling failure of rock mass/soil slope is an important geological and environmental problem. Clarifying its failure mechanism under different conditions has great significance in engineering. The toppling failure of a cutting slope occurred in a hydropower station in Kyushu, Japan illustrates that the joint characteristic played a significant role in the occurrence of rock slope tipping failure. Thus, in order to consider the mechanical properties of jointed rock mass and the influence of geometric conditions, a simplified analytical approach based on the limit equilibrium method for modeling the flexural toppling of cut rock slopes is proposed to consider the influence of the mechanical properties and geometry condition of jointed rock mass. The theoretical solution is compared with the numerical solution taking Kyushu Hydropower Station in Japan as one case, and it is found that the theoretical solution obtained by the simplified analysis method is consistent with the numerical analytical solution, thus verifying the accuracy of the simplified method. Meanwhile, the Goodman-Bray approach conventionally used in engineering practice is improved according to the analytical results. The results show that the allowable slope angle may be obtained by the improved Goodman-Bray approach considering the joint spacing, the joint frictional angle and the tensile strength of rock mass together.

The failure of soil slopes is usually triggered by rainfall infiltration. Under the rainfall infiltrating, soils transform from unsaturated state to saturated state, the matric suction gradually disappears, pore water pressure increases, and the safety factor of soil slopes decreases. In this paper, a novel rigorous limit equilibrium method is proposed to investigate the stability of unsaturated-saturated soil slopes under rainfall infiltration. The force equilibrium conditions along three coordinate axes and the overall moment equilibrium conditions around three coordinate axes are all strictly satisfied, which are more coincident with the real force state of the slopes. In addition, the seepage fields of soil slopes are investigated by using SEEP/W software. Then, the seepage fields are introduced to the rigorous limit equilibrium method. The effects of rainfall intensity, rainfall patterns and rainfall duration on the stability of the unsaturated-saturated soil slopes are investigated using the proposed method. For the unsaturated soils, in which there exists the matric suction, and the matric suction can improve the stability of soil slopes. The safety factors of soil slops under the different rainfall intensity and rainfall patterns are investigated. Moreover, the stability of Fanlingqian slope under rainfall infiltration is analyzed to verify the correctness and precision of the proposed method.