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Reliability analysis of sheet pile wall in spatially variable soil including CPTu test results

Kawa M., Baginska I., Wyjadlowski M.

Archives of Civil and Mechanical Engineering

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2019

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Vol. 19, no. 2

598--613

EN

The paper deals with reliability analysis of cantilever sheet pile wall located in non-cohesive soil with random properties. Spatial variability of friction angle has been described using random fields theory. The influence of both vertical as well as horizontal scale of fluctuation on the mechanical response of sheet pile wall is investigated. Deflection of wall top as well as maximum bending moment in the sheet pile wall are tested. The point distribution of soil friction and its vertical fluctuation scale is estimated using quasi-continuous results of cone penetrometer tests (CPTu). The boundary value problem is solved using finite difference code FLAC. The Fourier series method (FSM) allowing for non-uniform meshes is used to generate random fields for individual realizations. By utilizing Monte Carlo Simulation (MCS) technique the probability distributions of the results for different values of vertical and horizontal scales of fluctuation are obtained and used for reliability analysis. The results of analysis show that in case of cantilever sheet pile wall it is very important to properly estimate value of vertical fluctuation scale for the reliability analysis. It is also illustrated that in the considered problem horizontal scale of fluctuation significantly influences probability of failure.

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The reliability analysis of sheet pile wall located in soil with random properties based on CPTu results

Kawa M., Wyjadłowski M.

Engineering Transactions

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2017

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Vol. 65, iss. 1

193--200

EN

The paper deals with reliability analysis of sheet pile wall located in soil with strong spatial variability of strength properties. The purely frictional soil with the strength governed with Mohr-Coulomb criterion has been considered. Spatial variability of friction has been described using random fields theory. Implementation of Local Average Subdivision (LAS) algorithm has been used for generation of individual realizations of the field. Mean and variance as well as fluctuation scale of friction angle has been estimated for assumed exponential correlation model using the results obtained with CPTu testing in natural non-cohesive soil. Using the generated unidirectional field of friction the probabilistic analysis of sheet pile wall has been performed with finite difference method (FLAC). In the final step of the calculation, reliability analysis have been applied. The obtained results prove usefulness of the presented methodology for reliability based design of sheet pile walls.

3

Random analysis of bearing capacity of square footing using the LAS procedure

Kawa M., Puła W., Suska M.

Studia Geotechnica et Mechanica

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2016

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Vol. 38, nr 3

3--13

EN

In the present paper, a three-dimensional problem of bearing capacity of square footing on random soil medium is analyzed. The random fields of strength parameters c and φ are generated using LAS procedure (Local Average Subdivision, Fenton and Vanmarcke 1990). The procedure used is re-implemented by the authors in Mathematica environment in order to combine it with commercial program. Since the procedure is still tested the random filed has been assumed as one-dimensional: the strength properties of soil are random in vertical direction only. Individual realizations of bearing capacity boundary-problem with strength parameters of medium defined the above procedure are solved using FLAC3D Software. The analysis is performed for two qualitatively different cases, namely for the purely cohesive and cohesive-frictional soils. For the latter case the friction angle and cohesion have been assumed as independent random variables. For these two cases the random square footing bearing capacity results have been obtained for the range of fluctuation scales from 0.5 m to 10 m. Each time 1000 Monte Carlo realizations have been performed. The obtained results allow not only the mean and variance but also the probability density function to be estimated. An example of application of this function for reliability calculation has been presented in the final part of the paper.