Sina Javankhoshdel

• Ph.D., P.Eng. A.M.ASCE
• Geomechanics Product Manager at Rocscience Inc.

Design charts to estimate the factor of safety for simple slopes with cohesive-frictional (c-ϕ) soils are now available in the literature; however, the factor of safety is an imperfect measure for quantifying the margin of safety of a slope because nominal identical slopes with the same factor of safety can have different probabilities of failure d...

This paper focuses on the calculation of probability of failure of simple unreinforced slopes and the influence of the magnitude of cross correlation between soil parameters on numerical outcomes. A general closed-form solution for cohesive slopes with cross correlation between cohesion and unit weight was investigated and results compared with cas...

A general closed-form solution for the true probability of failure of a simple limit state function with one load term and one resistance term is derived. The formulation considers contributions due to model type, uncertainty in method bias values, bias dependencies, uncertainty in estimates of nominal values for correlated and uncorrelated load an...

Reinforced slopes with horizontal layers of geosynthetic reinforcement can have different mechanisms of failure. In this paper two major mechanisms of failure of reinforced slopes are investigated. External mechanisms occur when the critical slip surface passes beyond the reinforced zone. Internal mechanisms are characterised by failure surfaces th...

The 2D random finite element method and the one-dimensional and 2D random limit equilibrium method are used to investigate the influence of spatial variability of soil strength parameters on the probability of failure of simple soil slopes with cohesive undrained shear strength. The combined influence of spatial variability of soil properties and c...

Rock mass classification is fundamental for evaluating rock mass quality, essential for stability analysis and geotechnical design. Traditional classification methods are limited by joint observation technology, which typically gathers joint information from one-dimensional or two-dimensional perspectives, failing to comprehensively capture three-d...

With the ongoing development of urban areas, excavation plays a vital role in building construction, requiring careful consideration of safety from a geotechnical standpoint. Tied-back walls serve as a cost-effective solution for supporting excavations. This study focuses on the geotechnical engineering and stability analysis of tied-back urban dee...

Geosynthetics are commonly considered to provide restoring forces against sliding during overall slope stability analyses. Where a slipping surface intersects a geosynthetic layer, the geosynthetic layer produces a reaction force either in the opposite direction of sliding, in the direction of the geosynthetic alignment, or in some intermediate dir...

Soil hydraulic conductivity significantly influences the stability of embankment slopes by governing water seepage and water balance in soils. Spatial variability of this parameter can affect slope stability, making reliance on deterministic values potentially inaccurate, as shown by previous studies. This paper investigates the impact of spatial v...

In response to challenges in the design process of concrete arch pre-supporting systems (CAPS) for urban subway stations, we propose a novel approach that integrates robust multi-objective decision-making, ensemble learning, and clustering algorithms. This integrated framework aims to achieve an optimal design by considering both design objectives...

Geosynthetics are commonly considered to provide restoring forces against sliding during overall slope stability analyses. Where a slipping surface intersects a geosynthetic layer, the geosynthetic layer produces a reaction force either in the opposite direction of sliding, in the direction of the geosynthetic alignment, or in some intermediate dir...

In slope stability, weak layers are thin layers of low-strength materials which can potentially form part of the critical sliding surface. The search for the critical slip surface in slope stability is a complicated optimization problem that minimizes the factor of safety by altering the parameters corresponding to the geometry of a slip surface. W...

Determining parameters, including geomechanical characteristics of rocks or rock mass, initial stress state, underground water conditions, permeability, etc., with high accuracy is difficult and expensive due to the complexity of the geological conditions. On the other hand, analyzing the stability of tunnels and determining the behavioral characte...

Studies have shown that embankments built with fine materials such as silt are more susceptible to extreme rainfall events than those built with coarse materials. In most of these studies, it was assumed that soil strength and hydraulic parameters such as unit weight, friction angle, cohesion, and hydraulic conductivity are random variables. Howeve...

Due to the continuous development of urban areas, excavation has become a crucial part of the building’s construction. From the geotechnical point of view, excavation safety must be considered. Nail walls are an economical solution, widely used to support excavations. In this study, the construction of a nailed wall is simulated using a limit equil...

A novel method involving the transformation of spline surfaces is introduced to search for the critical slip surface in a three-dimensional (3D) slope, which corresponds to the minimum limit equilibrium method factor of safety for overall slope stability. A slipping surface in a slope can be represented as the intersection of any continuous geometr...

The FEM software RS2's efficiency in modelling an MSE wall was verified through numerical simulation of the significant structural components of a field-constructed MSE wall in Seattle, Washington. A 10.7-meter high wall was simulated, and its performance was evaluated by plotting strain and load profiles for different geogrid reinforcement layers...

The paper demonstrates the use of the response surface method (RSM) to carry out probabilistic assessment of the seismic bearing capacity of shallow footings seated near naturally occurring heterogeneous slopes. To this end, a pseudo-static loading is applied to a randomly uniform slope, which is homogeneous in each case but random between realizat...

The PowerPoint presentation at ARMA 2022

Three-dimensional (3D) slope stability analysis of a landslide is carried out using Limit Equilibrium Method (LEM) of analysis and Finite Element Method (FEM) of Analysis. FEM has the ability to find different critical regions with the maximum shear strain. Traditional LEM slope stability analysis methods seek to locate one single critical failure...

Piles are often used to reinforce slopes as they increase the available restoring force when calculating the factor of safety against sliding. In this paper, a 3D model of a slope containing multiple modes of failure is reinforced using pile elements. The results of the 3D Limit Equilibrium analysis containing piles are obtained using a newly intro...

Piles can be employed to increase the available restoring force, and subsequently the factor of safety of sliding in slopes. In this paper, a 3D model of a slope exhibiting multiple failure modes with factor of safety near unity is reinforced using pile elements. The results of the analysis with piles are obtained using a new coupled approach which...

Gabion walls are a form of retaining wall composed of modular steel baskets typically filled with rock. Gabion retaining structures have seen an increase in popularity and use due to their aesthetic properties and structural strength. Very few solutions to modelling gabion walls exist in the literature, lacking especially in limit equilibrium analy...

Slope instability is one of the major problems in geotechnical engineering. Slope instability affects both man-made and natural slopes and may cause significant economic damage, and sometimes injuries and loss of lives. During the construction of the Musandam Independent Power Plant (MIPP) in Northern Oman, a rock slope failure occurred on a benche...

Limit equilibrium analyses were conducted using pseudo-static approach to investigate the behavior of a typical reinforced slope under seismic loading. Slope height, slope face inclination, internal friction angle of the fill materials and seismic acceleration coefficients were all varied so that the length and tensile strength requirements of the...

Copyright 2022 ARMA, American Rock Mechanics Association This paper was prepared for presentation at the 56th US Rock Mechanics/Geomechanics Symposium held in Santa Fe, New Mexico, USA, 26-29 June 2022. This paper was selected for presentation at the symposium by an ARMA Technical Program Committee based on a technical and critical review of the pa...

The evaluation of slope stability of a three-dimensional slope requires identifying the critical slip surface with the minimum factor of safety, which is a complex optimization problem. Failure to identify the critical slip surface can lead to unconservative conclusions about the stability of a slope. This paper proposes a novel 3D surface-altering...

The disturbance factor (D) is a parameter in the Generalized Hoek-Brown failure criterion for rock slopes in slope stability. It represents the subsurface damage to the rock material properties resulting from blasting and stress relaxation during excavations. Within the region of assumed damage, a number between zero (undisturbed) and unity (very d...

Relief wells are commonly used to reduce the pore water pressure on the riverside of levees, thereby reducing the risk of levee and embankment failure. Two-dimensional slope stability analysis is typically used to analyze the stability of the levee. It assumes that relief wells have infinite length normal to the 2D plane of the model. This study co...

This paper combines transient groundwater analysis with a Random Limit Equilibrium Method (RLEM) to assess the safety of an embankment dam under water level variations. To this end, shear strength parameters, i.e., cohesion and friction angle, are modeled as random variables. The prevailing uncertainties of soil hydraulic characteristics are taken...

Relief wells are commonly used to reduce the pore water pressure on the river-side of levees, thereby reducing the risk of levee and embankment failure. Two-dimensional slope stability analysis is typically used to analyze the stability of the levee. It assumes that relief wells have infinite length normal to the 2D plane of the model. This study c...

This paper combines transient groundwater analysis with a Random Limit Equilibrium Method (RLEM) to assess the safety of an embankment dam under water level variations. To this end, shear strength parameters, i.e., cohesion and friction angle, are modeled as random variables. The prevailing uncertainties of soil hydraulic characteristics are taken...

The process of designing the support system of a subway station using a concrete arch pre-supporting system (CAPS) construction method includes an estimation of design variables based on intuition and experience. However, this process may often lead to controversial and economically unfavorable designs. In this regard, developing an optimization mo...

Spatial variability of soil deposits is an indispensable characteristic of natural deposits, which is due predominantly to the sedimentation process and chemical composition of the medium during formation of soil deposits. Innumerable researchers in literature have long investigated the impact of the spatial variability of soil strength and stiffne...

The Limit Equilibrium (LE) analysis of pile-supported geotechnical structures normally assumes a constant shear force for the pile instead of considering the non-linear capacity of the pile which is related to the pile displacement. In this study, a 3D Limit Equilibrium analysis is carried out for a landslide model supported with piles by consideri...

Finding the critical slip surface on a three-dimensional slope is a complex optimization problem. Failure to identify it can lead to unconservative conclusions about the stability of a slope and its factor of safety. This paper outlines the novel 3D Surface Altering Optimization method, which iteratively alters the geometry of a 3D slip surface to...

The conventional pseudo-dynamic (CPD) and modified pseudo-dynamic (MPD) methods are invoked to obtain the seismic bearing capacity of strip foundations using the limit equilibrium method, with a two-wedge failure mechanism. A spectral version of the conventional pseudo-dynamic method (SPD) is also invoked by considering the ground motion amplificat...

Large-scale landslides in sensitive clays are common in eastern Canada. Once initiated, failure occurs quite rapidly, essentially in undrained conditions. Based on the initiation and progression of the sliding surfaces or shear bands, the failure of slopes can be divided into two categories, namely upward and downward progressive failures. Upward p...

In this study, the well-established pseudo-static approach along with the horizontal slices method (HSM) is employed to investigate the seismic internal stability of geosynthetic-reinforced earth slopes. Previous simple HSM analyses were based on a primary assumption stating that the normal inter-slice forces are exerted on the mid-length of horizo...

Three-dimensional slope stability analysis of open pit mines is carried out using Limit Equilibrium Method (LEM) of analysis and Finite Element Analysis (FEM). Finite Element analysis has the ability to find different critical regions with the maximum shear strain. However, traditional LEM slope stability analysis methods seek to locate one single...

The purpose of this study is to examine the behavior of simple soil slopes reinforced with geosynthetics using deterministic and stochastic as well as circular and noncircular limit equilibrium method (LEM) of slope stability analyses. Two particular types of stochastic analyses, namely single random variable analyses and spatial variability analys...

In geotechnical engineering, most of the parameters have an inherent variability which should be considered in the analysis and design to attain more reliable results. The object of this study is to investigate the influence of the variability of soil strength parameters on the variability of the factor of safety of soil nail walls using the probab...

Three-dimensional (3D) probabilistic slope stability analysis using limit equilibrium methods is a time-consuming procedure. Using traditional sampling methods such as Monte Carlo or Latin hypercube may take days of computation, especially when there are multiple random variables and complicated geometries involved. Stochastic response surface (SRS...

Limit equilibrium (LE) slope stability analysis methods are typically combined with global search methods to locate a single critical slip surface, which corresponds to the minimum factor of safety for a topographical model. However, in complicated 3D models there often exist multiple modes of failure with similar factors of safety within the topog...

Large-scale landslides in sensitive clays are common in eastern Canada. Failure occurs quite rapidly, essentially in undrained conditions. Based on initiation and progression of the sliding surfaces or shear bands, the failure of slopes can be divided into two categories, namely upward and downward progressive failures. Upward progressive failure m...

Probabilistic analyses are often employed in slope stability analyses to account for the uncertainty associated with local variations in subsurface conditions. Practically, the consideration of spa-tially and stochastically varying soil properties is commonly achieved in combination with limit equilibrium methods to calculate the factor of safety....