Degree of Consolidation

(Constant, Variable, and Cyclic Loadings)

by the

Program Quick ELPLA

This book describes procedures and methods available in Quick ELPLA to analyze the problem of time-dependent consolidation of clay. The methods consider various analysis aspects of the consolidation problem such as, among others: uniform and time-dependent loading, cycling loading, nonlinear compressibility parameters, multi-layered soil, normal- and over-consolidated clay. The initial applied stress on the clay layers may be considered non-uniform.

Quick ELPLA has been developed for solving time-dependent settlement problems of clay layers using three different numerical methods:

·         Layer Equation Method (LEM), that was developed by Herrmann/ El Gendy (2014).

·         Finite Difference Method (FDM), that is the traditional solution of consolidation problems.

·         Eigen Value Method (EVM).

Although a more practical and meshless method LEM was developed for the program, the old one of FDM was considered because many geotechnical engineers are familiar with it. The developed LEM method depends on selecting a number of nodes in the soil layers. Consequently, a better representation for applied stresses on the layers can be represented. LEM requires fewer equation terms, in which a few terms are sufficient to give good results.

El Gendy, O. (2016) had carried out a numerical modification on the semi-analytical solution of Toufig and Ouria (2009) to be applicable for multi-layered soil subjected to any variable stress along the depth of the soil using LEM. Some of verification examples for cyclic loading on multi-layered soil carried out by him are presented in the this book.

Many tested examples are presented to verify and illustrate the available methods. Furthermore, an application for LEM on reloading time-dependent settlement of clay is presented in which a deep excavation is necessary for buildings with basements. In this case, the soil stress reduces due to excavation, and the reloading of the soil should be taken into account.