Behavior of Cantilever Concrete Diaphragm Wall Under Sequential Excavation of Front-Fill Soil: A Numerical Study

Abstract

A diaphragm wall is a concrete retaining wall constructed in a deep excavation on congested sites, incredibly close to existing structures. In this paper, a numerical study by a finite element program of ABAQUS was made on a cantilever concrete diaphragm wall of 30 m high with stratified sand deposits under natural and modified soil conditions. In the present study, sequential excavation of soils was done in front of the wall. The excavation of a total of 15 m deep was performed by lifting excavated soil in six steps, the thickness of each lift being 2.5 m. This paper analyzed the effects of different magnitudes of surcharge strip loadings on the diaphragm wall by varying loading positions from the edge of the wall. Wall deflections, bending moments, ground settlements, and horizontal earth pressures were investigated. It was observed that due to modification of front-fill foundation soil, the maximum deflection of the wall reduces by an average value of 0.55 times the deflection obtained in natural soil. This reduction is independent of the magnitude of the surcharge load and its position. The bending moment was reduced slightly, but the ground settlements were found to be reduced significantly. The magnitude of horizontal earth pressures produced along the wall's depth reaches its maximum value in modified soil conditions. Therefore, it may be concluded that the results of the present investigation may be helpful to the design engineers in selecting a suitable diaphragm wall section in loose foundation soil.KeywordsDiaphragm wallFinite element analysisWall deflectionWall bending momentGround settlement