Numerical Study of Optimal Location of Non-Circular Segmented Failure Surface in Soil Slope With Weak Soil Layer

2021 ◽  
Vol 12 (1) ◽  
pp. 111-141
Author(s):  
Navneet Himanshu ◽  
Avijit Burman ◽  
Vinay Kumar
Keyword(s):  
Numerical Study ◽  
Soil Layer ◽  
Failure Surface ◽  
Detailed Comparison ◽  
Global Optimum ◽  
Weak Soil ◽  
Critical Failure Surface ◽  
Potential Failure ◽  
Swarm Size ◽  
Contemporary Standard

The article addresses stability analysis of complicated slopes having weak soil layer sandwiched between two strong layers. The search for critical failure surface and associated optimum/minimum factor of safety (FOS) among all potential failure surfaces can be posed as an optimization problem. Two different variants of particle swarm optimization (PSO) models, namely inertia weight-based PSO (IW-PSO) and contemporary standard PSO (CS-PSO), are used to obtain optimum global solution. Detailed comparison between the global optimum solutions obtained from two PSO variants and the effect of swarm size is studied. The performance of IW-PSO and CS-PSO are studied by observing the convergence behavior of the respective algorithms with respect to iteration count. The influence of velocity clamping on the optimized solution is investigated and its use is found beneficial as it prevents the solution from overflying the region with global best solution. The studies related to swarm diversity demonstrating the exploitation and exploration behaviors of the algorithms are also presented.

scholarly journals Numerical Study of the Behavior of Back-to-Back Mechanically Stabilized Earth Walls

Geotechnics ◽  
2021 ◽  
Vol 1 (1) ◽  
pp. 18-37
Author(s):  
Seyed Hamid Lajevardi ◽  
Khashayar Malekmohammadi ◽  
Daniel Dias
Keyword(s):  
Numerical Study ◽  
Failure Surface ◽  
Friction Angle ◽  
Soil Reinforcement ◽  
Mechanically Stabilized Earth ◽  
Surface Shear ◽  
Mechanically Stabilized Earth Walls ◽  
Critical Failure Surface ◽  
Mechanically Stabilized ◽  
Earth Walls

Back-to-back mechanically stabilized earth (MSE) walls can sustain significant loadings and deformations due to the interaction mechanisms which occur between the backfill material and reinforcement elements. These walls are commonly used in embankments approaching bridges, ramps, and railways. The performance of a reinforced wall depends on numerous factors, including those defining the soil, the reinforcement, and the soil/reinforcement interaction behavior. The focus of this study is to investigate the behavior of back-to-back mechanically stabilized earth walls considering synthetic and metallic strips. A two-dimensional finite difference numerical modeling is considered. The role of the soil friction angle, the distance of the reinforcement elements, the walls’ width to height ratio, and the quality of the soil material are investigated in a parametric study. Their effects on the critical failure surface, shear displacements, wall displacements, and tensile forces on the reinforcements are presented. The interaction between back-to-back reinforced walls strongly depends on the distance between walls and modifies the critical failure surface location.

scholarly journals A Comprehensive Numerical Study on Building-Excavation Interaction

2020 ◽  
Vol 6 (2) ◽  
pp. 326-343
Author(s):  
Arman Maddah ◽  
Abbas Soroush
Keyword(s):  
Numerical Study ◽  
Failure Surface ◽  
Embedment Depth ◽  
Deep Excavation ◽  
Building Foundation ◽  
Potential Failure ◽  
Building Characteristics ◽  
Parametric Analyses ◽  
3D Software ◽  
Story Building

This paper presents results of a plane strain comprehensive numerical study on the interaction between a 31-meter-deep excavation and an adjacent 12-story building; the study emphasizes on parametric analyses with respect to the building characteristics, such as the building width in plan (B), i.e., the side perpendicular to the excavation wall, the embedment depth of the building foundation (D), as well as the building distance to the excavation edge (e). Through the parametric analyses and assuming different values for B, D, and e, settlements and rotations of the building and horizontal displacements of the excavation edge were computed and evaluated using the finite element method adopted in PLAXIS 3D software. Prior to the parametric study, the numerical modeling was verified by modeling a recorded case study, which is an anchored deep excavation adjacent to a 12-story building. The results of the parametric analyses suggest that for the given soil and excavation, (1) the position of the developing potential failure surface, PFS, in the soil behind the excavation is almost independent from the building location and (2) the position of the building with respect to the outcrop of the PFS in the excavation crest, i.e., if the building locates fully on the potential failure wedge or PFS intersect the building base, is the main factor affecting the induced displacements and rotations of the building.

Technical Review of Slope Failure (Case Study of Tawangmangu-Cemorosewu Sta. 4+600 Section)

2016 ◽  
Vol 845 ◽  
pp. 76-82
Author(s):  
Alik Mustakim ◽  
Yusep Muslih Purwana ◽  
Ary Setyawan ◽  
Mamok Suprapto
Keyword(s):  
Safety Factor ◽  
Slope Failure ◽  
Soil Layer ◽  
Failure Surface ◽  
Finite Element Software ◽  
Central Java ◽  
Safety Reason ◽  
Critical Failure Surface ◽  
Reasonable Choice ◽  
Failure Location

Tawangmangu-Sarangan highway is a national strategic road connecting two districts in two provinces; Karanganyar in Central Java and Magetan in East Java. The topography of the area is relatively high due to stiff hill and valley with the problematic geologic condition of weathered rock and silt sand. During rainy season, slope failures at some sections of this road were very often. The study to understand the cause of the failures is very important. Deep boring may have the best result to obtain soil parameter and stratigraphy of soil layer. However, this method was impossible due to the safety reason. The use of geophysic instrument such as geoelectric for the investigation combined with hand boring for soil sampling was a reasonable choice. Geoelecetric was utilized to predict soil layers properties and potential failure surface of the slope. This study was focused on the investigation on a slope failure location of Tawangmangu-Cemorosewu at Sta 4+600. Finite element software was utilized to understand the cause of previous failure and to model the most critical failure surface that may occurre in the future. Based on the modeling, the safety factor of the slope was 1.18 and 0.930 before and during construction. The condition of the slope after failure is still very critical due to the very low safety factor of 1.03 causing the potential of failure. It also recommended that geometrical method such as terrasering might be one of the solutions producing the safety fractor of 1.5.

scholarly journals 3-D Numerical Study of Mechanical Behaviors of Pile-Anchor System

2014 ◽  
Vol 580-583 ◽  
pp. 238-242
Author(s):  
Ri Cheng Liu ◽  
Bang Shu Xu ◽  
Bo Li ◽  
Yu Jing Jiang
Keyword(s):  
Simulation Analysis ◽  
Numerical Study ◽  
Bending Moments ◽  
Mechanical Behaviors ◽  
Foundation Pit ◽  
Anchor System ◽  
Anchor Cable ◽  
Axial Forces ◽  
Toppling Failure ◽  
Potential Failure

Mechanical behaviors of pile-soil effect and anchor-soil effect are significantly important in supporting engineering activities of foundation pit. In this paper, finite difference method (FDM) was utilized to perform the numerical simulation of pile-anchor system, composed of supporting piles and pre-stressed anchor cables. Numerical simulations were on the basis of the foundation pit of Jinan’s West Railway Station, and 3D simulation analysis of foundation pit has been prepared during the whole processes of excavation, supporting and construction. The paper also analyzed the changes of bending moments of piles and axial forces of cables, and discussed mechanical behaviors of pile-anchor system, through comparisons with field monitoring. The results show that the parameters concluding vertical gridding’s number, cohesion of pile and soil, and pile stiffness have robust influences on supporting elements’ behaviors. Mechanical behaviors of supporting pile and axial forces of anchor cable changed dramatically, indicating that the potential failure form was converted from toppling failure to sliding failure.

scholarly journals A Theoretical Consideration of the Strength of Snow

1966 ◽  
Vol 6 (43) ◽  
pp. 159-170 ◽  
Author(s):  
G. E. H. Ballard ◽  
E. D. Feldt
Keyword(s):  
Theoretical Consideration ◽  
Failure Surface ◽  
Maximum Strength ◽  
Age Hardening ◽  
Temperature Dependent ◽  
Dependent Parameter ◽  
Potential Failure ◽  
Image Position

AbstractA consideration of possible expressions for the number and size of bonds intersected by a potential failure surface leads to the following expression for the strength of snow, σf, which is age-hardening at a constant porosity n: where σi is the strength of ice, tf is the time at failure, α is a parameter specifically related to the mechanism of bonding, and ω is a temperature-dependent parameter. Allowing tf to become infinite provides the envelope of maximum strength for fully age-hardened snow at any porosity n.

scholarly journals The circulation of the Persian Gulf: a numerical study

2005 ◽  
Vol 2 (3) ◽  
pp. 129-164 ◽  
Author(s):  
J. Kämpf ◽  
M. Sadrinasab
Keyword(s):  
United Arab Emirates ◽  
Persian Gulf ◽  
Thermal Stratification ◽  
Numerical Study ◽  
Three Dimensional ◽  
Detailed Comparison ◽  
Mass Properties ◽  
Inverse Estuary ◽  
The Persian Gulf ◽  
Autumn And Winter

Abstract. We employ a three-dimensional hydrodynamic model (COHERENS) to study the circulation and water mass properties of the Persian Gulf, which is a large inverse estuary. Our findings suggest that the Persian Gulf experiences a distinct seasonal cycle in which a Gulf-wide cyclonic overturning circulation establishes in spring and summer, but this disintegrates into mesoscale eddies in autumn and winter. Establishment of the Gulf-wide circulation coincides with establishment of thermal stratification and strengthening of the baroclinic exchange circulation through the Strait of Hormuz. The latter is associated with winter cooling of extreme saline (>45 psu) water in shallow regions along the coast of United Arab Emirates. To validate the model results, we present a detailed comparison with observational evidence.

Simulation Optimization Using Multi-Time-Scale Adaptive Random Search

2019 ◽  
Vol 36 (06) ◽  
pp. 1940014
Author(s):  
Qi Zhang ◽  
Jiaqiao Hu
Keyword(s):  
Search Algorithm ◽  
Numerical Study ◽  
Random Search ◽  
Solution Space ◽  
Population Based ◽  
Global Optimum ◽  
Adaptive Random Search ◽  
Candidate Solution ◽  
Approximation Type ◽  
Effective Use

We propose a random search algorithm for seeking the global optimum of an objective function in a simulation setting. The algorithm can be viewed as an extension of the MARS algorithm proposed in Hu and Hu (2011) for deterministic optimization, which iteratively finds improved solutions by modifying and sampling from a parameterized probability distribution over the solution space. However, unlike MARS and many other algorithms in this class, which are often population-based, our method only requires a single candidate solution to be generated at each iteration. This is primarily achieved through an effective use of past sampling information by means of embedding multiple nested stochastic approximation type of recursions into the algorithm. We prove the global convergence of the algorithm under general conditions and discuss two special simulation noise cases of interest, in which we show that only one simulation replication run is needed for each sampled solution. A preliminary numerical study is also carried out to illustrate the algorithm.

scholarly journals An Extension of Taylor’s φ-Circle Method and Some Stability Charts for Submerged Slopes

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Ping Li ◽  
Luanhua Dong ◽  
Xiaowen Gao ◽  
Tonglu Li ◽  
Xiaokun Hou
Keyword(s):  
Analytical Solutions ◽  
Factor Of Safety ◽  
Classical Method ◽  
Circle Method ◽  
Failure Surface ◽  
Underground Water ◽  
Submerged Condition ◽  
Stability Calculation ◽  
Critical Failure Surface ◽  
Underground Water Table

Taylor’s φ-circle method is a classical method for slope stability calculation, which has analytical solutions. Taylor derived equations in two cases separately, namely, (i) the outlet of the critical failure surface is at the slope toe and (ii) the outlet of the failure surfaces is not at the slope toe. The method is only appropriate for two conditions (without underground water table in slopes or totally submerged slopes). In this study, a general equation that unifies the equations of the two cases is proposed and partially submerged condition is introduced. The critical failure surfaces corresponding to the minimum factor of safety are determined using the computer program proposed by the authors. The general expression of the safety factor of slopes under the following four conditions is derived, namely, (i) partly submerged, (ii) completely submerged, (iii) water sudden drawdown, and (iv) water slow drawdown. The corresponding charts for practical use are available.

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