Use of diaphragm walls to mitigate ground movements induced by tunnelling

Abstract

Tunnelling in urban areas can damage the existing buildings and underground services, as a consequence of ground movements induced by excavation. In this paper the potential of a vertical diaphragm wall to modify the displacement field induced by tunnel excavation is investigated. A series of centrifuge tests were performed in which a diaphragm wall was embedded to one side of a tunnel. The location of the wall, its length, thickness and the roughness of the wall–soil interface were varied. In addition, a series of numerical analyses were carried out to supplement the experimental data. It was observed that the field of displacements was modified in different ways, depending on the combination of the above factors, and the sensitivity of the problem to the variation of each factor is discussed. An efficiency parameter is defined that expresses the ability of the wall to modify the reference (no wall) profile of settlements.