Estimation of Fill properties behind a deep excavation by back analysis

Abstract

Accurate prediction of soil parameters is a challenge to braced excavation systems design, especially when the wall retains “Fill” containing artificial materials. This paper presents a case study of a braced diaphragm in situ wall supporting 14 m of Fill in Egypt with the objective of estimating representative parameters for the Fill. The wall, designed based on conservative strength and deformation parameters, was monitored using inclinometers. Back analysis is conducted to determine representative Fill parameters using the beams on elastic foundation (BEF) and finite element (FE) methods. The FE analysis is conducted using the hardening soil constitutive model, and a comparison is made with Mohr–Coulomb (MC) model. The results show that the hardening soil model can reproduce the wall movement better than MC model and the BEF method. Hence, representative parameters are estimated for the retained Fill. It is illustrated that adopting the deduced values could result in considerable savings.