Three-dimensional upper-bound analysis for ultimate bearing capacity of laterally loaded rigid pile in undrained clay

2015 ◽  
Vol 52 (11) ◽  
pp. 1775-1790 ◽  
Author(s):  
Jian Yu ◽  
Maosong Huang ◽  
Chenrong Zhang
Keyword(s):  
Bearing Capacity ◽  
Failure Mechanism ◽  
Plane Strain ◽  
Upper Bound ◽  
Three Dimensional ◽  
Soil Conditions ◽  
Soil Parameters ◽  
Collapse Mechanism ◽  
Layered Soils ◽  
Rigid Plastic

A new three-dimensional upper-bound combined failure mechanism is presented to analyze the lateral ultimate capacity of rigid piles embedded in various soil conditions, involving homogeneous soils, layered soils, and Gibson soils. The wedge curved failure surface function composed by rotating the Newton interpolation polynomial is adopted near the ground surface, and a plane strain collapse mechanism is employed at depth. Furthermore, the energy dissipation of the transition interface is introduced to keep a kinematically admissible velocity field between the wedge and the plane strain mechanism. An empirical equation is then proposed based on the upper-bound solutions for the homogeneous soils, and extended to the layered soils and Gibson soils. Meanwhile, the three-dimensional arbitrary Lagrangian–Eulerian (ALE) analysis is employed to investigate the distribution of limiting pressures along the pile shaft for different soil parameters. It is found that the upper-bound solutions based on the rigid-plastic assumption only exhibits a good agreement with the finite element (FE) results for a very high soil rigidity index of 10 000, due to a Possion’s ratio of approximate but less than 0.5 in such a typical undrained FE analysis. For such a Possion’s ratio, an inevitably slight elastic volumetric change induces the unexpected cavity flow at the deep section of the pile. It leads to the soil rigidity affecting the profile distribution of the bearing capacity, although it is not true for a real undrained analysis. Finally, a centrifuge test is analyzed by the upper-bound method to further testify the rationality of the new failure mechanism.

scholarly journals Saturated Ground Vibration Analysis Based on a Three-Dimensional Coupled Train-Track-Soil Interaction Model

2019 ◽  
Vol 9 (23) ◽  
pp. 4991 ◽  
Author(s):  
Li ◽  
Su ◽  
Kaewunruen
Keyword(s):  
High Speed ◽  
Three Dimensional ◽  
Interaction Model ◽  
Ground Vibration ◽  
Field Measurements ◽  
Soil Conditions ◽  
Layered Soils ◽  
Train Track ◽  
Dynamic Interactions ◽  
Vibration Responses

A novel three-dimensional (3D) coupled train-track-soil interaction model is developed based on the multi-body simulation (MBS) principle and finite element modeling (FEM) theory using LS-DYNA. The novel model is capable of determining the highspeed effects of trains on track and foundation. The soils in this model are treated as saturated media. The wheel-rail dynamic interactions under the track irregularity are developed based on the Hertz contact theory. This model was validated by comparing its numerical results with experimental results obtained from field measurements and a good agreement was established. The one-layered saturated soil model is firstly developed to investigate the vibration responses of pore water pressures, effective and total stresses, and displacements of soils under different train speeds and soil moduli. The multi-layered soils with and without piles are then developed to highlight the influences of multi-layered soils and piles on the ground vibration responses. The effects of water on the train-track dynamic interactions are also presented. The original insight from this study provides a new and better understanding into saturated ground vibration responses in high-speed railway systems using slab tracks in practice. This insight will help track engineers to inspect, maintain, and improve soil conditions effectively, resulting in a seamless railway operation.

Upper-bound solutions of three-dimensional passive earth pressures

2005 ◽  
Vol 42 (5) ◽  
pp. 1449-1460 ◽  
Author(s):  
S Škrabl ◽  
B Macuh
Keyword(s):  
Failure Mechanism ◽  
Upper Bound ◽  
Limit Analysis ◽  
Central Body ◽  
Three Dimensional ◽  
Failure Surface ◽  
Outer Side ◽  
Soil Pressure ◽  
Upper Bound Method ◽  
The Cross

This paper presents a novel approach to the determination of passive soil pressures: using the upper-bound method within the framework of limit analysis theory. It is based on a three-dimensional, kinematically admissible, rotational, hyperbolical failure mechanism. The failure mechanism is composed of the central and two lateral bodies, which are connected by a common velocity field. This approach is similar to two-dimensional stability analyses, where the log spiral potential failure surface is considered. The front surface of the central body interacts with the retaining wall; the upper surface can be loaded by surcharge loading; and the log spiral segment defines the curved failure surface of the central part. The cross sections of the lateral bodies are in agreement with the cross section of the central body. On the outer side, they are laterally bounded by a curved and kinematically admissible hyperbolic surface, which is defined by enveloping the hyperbolical half cones and part of the case surface of the leading half cone. The results give values for the passive soil pressure coefficients that are for most cases lower than the values determined by the upper-bound method of limit analysis for a translational failure mechanism, as published in the literature.Key words: limit analysis, earth pressure, passive pressure, failure surface, soil–structure interaction.

Bearing capacity of square spudcan of jack-up rig based on a three-dimensional failure mechanism

2013 ◽  
Vol 9 (2) ◽  
pp. 149-160 ◽  
Author(s):  
Jun Zhao ◽  
Menglan Duan ◽  
Aixia Zhang ◽  
Fei Wang ◽  
Minghui Zhang
Keyword(s):  
Bearing Capacity ◽  
Failure Mechanism ◽  
Three Dimensional ◽  
Jack Up

scholarly journals An iterative algorithm for random upper bound kinematical analysis

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Marcin Chwała
Keyword(s):  
Spatial Variability ◽  
Bearing Capacity ◽  
Covariance Matrix ◽  
Iterative Algorithm ◽  
Upper Bound ◽  
Three Dimensional ◽  
Soil Strength ◽  
Upper Bound Theorem ◽  
Practical Applications ◽  
Simplified Algorithm

Abstract A new approach for stochastic upper bound kinematical analyses is described. The study proposes an iterative algorithm that uses the Vanmarcke spatial averaging and kinematical failure mechanisms. The iterative procedure ensures the consistency between failure geometry and covariance matrix, which influences the quality of the results. The proposed algorithm can be applied to bearing capacity evaluation or slope stability problems. The iterative algorithm is used in the study to analyse the three-dimensional undrained bearing capacity of shallow foundations and the bearing capacity of the foundation for two-layered soil, in both cases, the soil strength spatial variability is included. Moreover, the obtained results are compared with those provided by the algorithm, based on the constant covariance matrix. The study shows that both approaches provide similar results for a variety of foundation shapes and scale of fluctuation values. Therefore, the simplified algorithm can be used for purposes that require high computational efficiency and for practical applications. The achieved efficiency using a constant covariance matrix for one realisation of a three-dimensional bearing capacity problem that includes the soil strength spatial variability results in about 0.5 seconds for a standard notebook. The numerical example presented in the study indicates the importance of the iterative algorithm for further development of the failure mechanism application in probabilistic analyses. Moreover, because the iterative algorithm is based on the upper bound theorem, it could be utilised as a reference for other methods for spatially variable soil.

Vertical bearing capacity factors for circular and strip footings on Mohr–Coulomb soil

1993 ◽  
Vol 30 (6) ◽  
pp. 1024-1033 ◽  
Author(s):  
M.D. Bolton ◽  
C.K. Lau
Keyword(s):  
Bearing Capacity ◽  
Plane Strain ◽  
Method Of Characteristics ◽  
Soil Parameters ◽  
Shape Factors ◽  
Method Of Solution ◽  
Vertical Bearing ◽  
Strip Footings ◽  
Vertical Bearing Capacity ◽  
The Relationship

The method of characteristics is used to establish consistent factors for the vertical bearing capacity of circular and strip footings on soil which satisfies a linear [Formula: see text] Mohr–Coulomb strength criterion. This method of solution avoids the assumption of arbitrary slip surfaces, and produces zones within which equilibrium and plastic yield are simultaneously satisfied for given boundary stresses. Although similar solutions have previously been published for circular footings, their application has been hindered by errors and confusions over terminology. These are resolved, and the method of solution is explained. It is confirmed that Terzaghi's approach to the superposition of bearing terms containing Nq, Nγ, and Nc is both safe and sufficiently accurate for circular footings, as for strip footings. The values to be adopted are tabulated as functions of [Formula: see text]. Differences between the factors applicable to circular and strip footings far exceed the allowances of the empirical shape factors in common use. Some new shape factors are suggested that better represent the relationship between the limiting equilibrium of circular and strip foundations. Some current shape factors attempt to allow simultaneously for the differences in equilibrium solutions and the differences in axisymmetric (triaxial) and plane strain soil parameters. This cannot succeed, since the relationship between strength parameters depends strongly on relative density. The new bearing factors facilitate a more rational approach in which soil parameters appropriate to the geometry can first be determined and then used to find appropriate bearing capacity factors. Key words : bearing capacity, axisymmetry, method of characteristics, footings, plane strain.

Failure Mechanism and Bearing Capacity of Shallow Foundation on Poorly Cemented Sandstone

2008 ◽  
Vol 24 (3) ◽  
pp. 285-296 ◽  
Author(s):  
J.-C. Chang ◽  
J.-J. Liao ◽  
Y.-W. Pan
Keyword(s):  
Bearing Capacity ◽  
Failure Mechanism ◽  
Upper Bound ◽  
Hard Rock ◽  
Model Tests ◽  
Shallow Foundation ◽  
Load Bearing ◽  
Bound Solution ◽  
Upper Bound Solution ◽  
Bearing Behavior

AbstractThis paper aims to investigate the failure mechanism of a shallow foundation on poorly cemented sandstone and to propose an upper bound solution for the bearing capacity of the foundation. A series of laboratory material and load-bearing model tests with specimens made of artificial rock mimic undisturbed natural poorly cemented sandstone.Based on a series of load-bearing model tests, bearing behavior and progressive failure mechanisms are investigated. It was found that the bearing behavior on poorly cemented sandstone is distinct from the cases on hard rock or on soil, and exhibits both plasticity and brittle characteristics. It is noted that the bearing capacity formulas for a shallow foundation commonly used for soil or hard rock are not appropriate for the case of poorly cemented soft sandstone. Based on the observed failure mechanism, a simplified plastic collapse mechanism is proposed and an upper-bound solution on the basis of a multi-block translation mechanism is formulated. It is shown that the upper bound solution agrees well with the experimental bearing capacity as long as a proper non-associated flow rule is adopted.

Evaluating the Bearing Capacity of a Soil Layer Overlying Rigid Substratum Using a Modified Failure Mechanism Based on Limit State Analysis

2013 ◽  
Vol 353-356 ◽  
pp. 806-814
Author(s):  
Reza Afshar-Mazandaran ◽  
Hadi Khabbaz
Keyword(s):  
Bearing Capacity ◽  
Failure Mechanism ◽  
Limit State ◽  
Soil Layer ◽  
Finite Depth ◽  
Bound State ◽  
Shallow Foundations ◽  
Collapse Mechanism ◽  
Parametric Studies ◽  
Spiral Surface

The bearing capacity of shallow foundations resting on a soil layer with a finite depth over bedrock has been studied for years by many investigators. Farzaneh et al (2010) introduced a rigorous bearing capacity analysis based on the upper bound state theorem, using a log-spiral surface algorithm. This paper presents a thorough evaluation of this collapse mechanism and subsequently, a modified failure mechanism is introduced. The collapse mechanism consists of rigid blocks under combined rotational and transitional movements. The effects of the loading parameters on bearing capacity results are then discussed. The findings of this study are compared with the original limit state mechanism as well as previously published solutions, emphasising the accuracy and efficiency of the modified mechanisms. Furthermore, parametric studies are carried out to evaluate the ultimate bearing capacity of shallow foundations resting on a restricted soil, layer using the proposed mechanism. Design tables are finally presented for practical use in geotechnical engineering.

Sign in / Sign up

Export Citation Format

Share Document