Two- and three-dimensional analyses of translational slides in soils with nonlinear failure envelopes

2010 ◽  
Vol 47 (4) ◽  
pp. 388-399 ◽  
Author(s):  
Hisham T. Eid
Keyword(s):  
Shear Strength ◽  
Dimensional Stability ◽  
Three Dimensional ◽  
Shear Resistance ◽  
Fast Method ◽  
Stability Number ◽  
Stability Function ◽  
Case Histories ◽  
Failure Envelopes ◽  
Soil Shear Strength

This paper aims to assess the effect of nonlinearity of the soil shear strength envelope on the sliding mass configurations and the minimum two- and three-dimensional factors of safety for slopes susceptible to translational failure in both static and seismic conditions. An extensive parametric study was conducted using slope models and nonlinear soil strength envelopes that simulate translational failure case histories. Analysis of the results led to the development of stability charts that do not require an iterative procedure when determining the factors of safety. The introduction of a two-dimensional stability number and three-dimensional stability function, the values of which depend on the degrees of nonlinearity of the involved soils’ strength envelopes, has made it possible to develop such charts. These charts give the practicing geotechnical engineer a reliable and fast method to analyze translational failures. Using available software in such an analysis can be complicated if shear resistance along the sliding mass vertical sides and nonlinearity of soil shear strength envelopes are considered. Numerical examples and a case history are given to verify the reliability and illustrate the different applications of these charts.

scholarly journals Evaluation of Undrained Bearing Capacities of Wide-Shallow Bucket Foundation with Honeycomb Bulkheads in Clay

2019 ◽  
Vol 2019 ◽  
pp. 1-13
Author(s):  
Qingshan Wang ◽  
Xun Han ◽  
Yunfei Guan ◽  
Yongyong Cao ◽  
Wenxuan Li
Keyword(s):  
Shear Strength ◽  
Three Dimensional ◽  
Offshore Wind ◽  
Combined Loading ◽  
Vertical Load ◽  
Bucket Foundation ◽  
Failure Envelopes ◽  
Soil Shear Strength ◽  
New Type ◽  
The Moment

As a new type of offshore wind foundation, the wide-shallow bucket foundation with honeycomb bulkheads mainly bears vertical, horizontal, and moment loads. As yet, no systematic study has been conducted regarding the effects of honeycomb bulkheads on the undrained bearing capacities of the wide-shallow bucket foundation. In this study, a large number of three-dimensional (3D) finite element (FE) analyses were performed to investigate the undrained bearing capacities of the wide-shallow bucket foundations with and without honeycomb bulkheads, thereby evaluating the influence of honeycomb bulkheads on the bearing capacities under different conditions. The results show that under uniaxial loading, the uniaxial bearing capacities of the wide-shallow bucket foundation are basically unaffected by the honeycomb bulkheads in homogeneous clay. For nonhomogeneous clay, the moment bearing capacity will be considerably enhanced with the increase in soil shear strength heterogeneity. Under combined loading, the honeycomb bulkheads will enhance the combined bearing capacities only in nonhomogeneous clay. The enhancement effects will increase with the increase in soil shear strength heterogeneity but decrease with the increase in vertical load. Besides, the simplified equations for calculating the uniaxial bearing capacities of the wide-shallow bucket foundation with honeycomb bulkheads are also proposed considering the influence of embedment ratio and soil shear strength heterogeneity. At last, the parameters of an approximating expression are fitted to predict the failure envelopes of this foundation under combined loading.

scholarly journals Effects of Vegetation Type on Soil Shear Strength in Fengyang Mountain Nature Reserve, China

Forests ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 490
Author(s):  
Xin Liu ◽  
Xuefei Cheng ◽  
Nan Wang ◽  
Miaojing Meng ◽  
Zhaohui Jia ◽  
...  
Keyword(s):  
Particle Size ◽  
Shear Strength ◽  
Nature Reserve ◽  
Vegetation Type ◽  
Mixed Forest ◽  
Shear Resistance ◽  
Vegetation Types ◽  
Broad Leaved Forest ◽  
Soil Shear Strength ◽  
Leaved Forest

Shear strength is an important mechanical property of soil, as its mechanical function plays critical roles in reducing land degradation and preventing soil erosion. However, shear strength may be affected by vegetation type through changes in the soil and root patterns. To understand the influences of different types of vegetation on shear strength, the soil shear indices of three typical vegetation types (broad-leaved forest, coniferous broad-leaved mixed forest, and grassland) were studied and evaluated at the Fengyang Mountain Nature Reserve, China. We employed a direct shear apparatus to measure the soil shear resistance index. We quantified the soil porosity, moisture content, and composition of particle size to determine the properties of the soil, and a root scanner was used to quantify the root index. The results revealed that there were significant differences in shear resistance indices at the stand level. Between the three vegetation types, the internal friction angle of the broad-leaved forest was the largest and the cohesion was the smallest. The soil moisture content and porosity of the coniferous broad-leaved mixed forest were higher than those of the broad-leaved forest, and the root volume density (RVD/cm3) of the broad-leaved forest was higher than that of the coniferous and broad-leaved mixed forest and grassland. Structural equation modeling results show that the soil particle size and root characteristics indirectly impacted the soil water content by affecting porosity, which finally affected shear strength. In general, there were significant differences in soil properties and plant root indices between the different stands, which had an impact on soil shear strength.

Bearing Capacities of Shallow Skirted Foundations After the Action of Multi-Directional Cyclic Displacements Considering Soil Degradation

2019 ◽  
Author(s):  
Zhong Xiao ◽  
Donghai Zhang ◽  
Haixiao Liu ◽  
Ying Liu
Keyword(s):  
Shear Strength ◽  
Soil Degradation ◽  
Soft Soil ◽  
Ocean Engineering ◽  
Loading Paths ◽  
Plastic Shear Strain ◽  
Failure Envelopes ◽  
Soil Shear Strength ◽  
Service State ◽  
Continuous Accumulation

Abstract Shallow skirted foundations have been applied widely in ocean engineering. Under the action of external excitation, the shallow skirted foundations on soft soil undergo cyclic displacements during service state. Under the action of cyclic displacements, the foundations drive the surrounding soft soil to produce a continuous accumulation of absolute plastic shear strain, which weakens the shear strength of the soft soil around the foundations. Therefore, the bearing capacities of shallow skirted foundations reduce after the action of cyclic displacements considering soil degradation. In order to study the evolutions of bearing capacities of shallow skirted foundations after the action of multi-directional cyclic displacements considering soil degradation, the elastoplastic finite element models of shallow skirted foundations with different embedment ratio are established. Cyclic displacements are applied along different displacement loading paths, and the evolutions of soil shear strength and bearing capacities of shallow skirted foundations after the action of cyclic displacements are analyzed. The results show that the soil softening zone gradually expands from the stress concentration zone of the soft soil to the surrounds with increasing number of loading cycles. Due to the enlargement and weakening of the soil softening zone, the failure envelopes of shallow skirted foundations gradually shrink, but the shrinkage trend gradually converges with increasing number of loading cycles. The shapes of the failure envelopes are relatively less affected by the cyclic number of displacements. The size of the failure envelopes is greatly affected by the loading paths while the shape of the failure envelopes is relatively less affected.

Finite Element Modeling of a Mechanically Stabilized Earth Trial Wall

2021 ◽  
pp. 036119812110164
Author(s):  
Andrew Lees ◽  
Michael Dobie
Keyword(s):  
Finite Element ◽  
Shear Strength ◽  
Retaining Wall ◽  
Back Analysis ◽  
Soil Parameters ◽  
Failure Behavior ◽  
Valuable Insight ◽  
Deformation And Failure ◽  
First Case ◽  
Soil Shear Strength

Polymer geogrid reinforced soil retaining walls have become commonplace, with routine design generally carried out by limiting equilibrium methods. Finite element analysis (FEA) is becoming more widely used to assess the likely deformation behavior of these structures, although in many cases such analyses over-predict deformation compared with monitored structures. Back-analysis of unit tests and instrumented walls improves the techniques and models used in FEA to represent the soil fill, reinforcement and composite behavior caused by the stabilization effect of the geogrid apertures on the soil particles. This composite behavior is most representatively modeled as enhanced soil shear strength. The back-analysis of two test cases provides valuable insight into the benefits of this approach. In the first case, a unit cell was set up such that one side could yield thereby reaching the active earth pressure state. Using FEA a test without geogrid was modeled to help establish appropriate soil parameters. These parameters were then used to back-analyze a test with geogrid present. Simply using the tensile properties of the geogrid over-predicted the yield pressure but using an enhanced soil shear strength gave a satisfactory comparison with the measured result. In the second case a trial retaining wall was back-analyzed to investigate both deformation and failure, the failure induced by cutting the geogrid after construction using heated wires. The closest fit to the actual deformation and failure behavior was provided by using enhanced fill shear strength.

Shear Strength Monitoring System Based on Measurement of Shear Wave Velocity and Moisture Content

2014 ◽  
Vol 635-637 ◽  
pp. 750-754
Author(s):  
Peng Hu ◽  
Qing Li ◽  
Yi Wei Xu ◽  
Nan Ying Shentu ◽  
Quan Yuan Peng
Keyword(s):  
Shear Strength ◽  
Moisture Content ◽  
Shear Wave ◽  
Monitoring System ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Bender Elements ◽  
Strength Measurement ◽  
Soil Shear Strength ◽  
The Relationship

Expound the importance of soil shear strength measurement at mudslide hidden point to release the loss caused by the disaster, explain the relationship between shear wave velocity, moisture content and shear strength, design the shear strength monitoring system combining the shear wave velocity measured by Piezoelectric bender elements and moisture content.

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