The behavior of tied-back retaining walls

Abstract

Rational design of an excavation support system that incorporates the retaining of the soil mass by a wall which is held by prestressed anchors (tie-backs) located in the retained soil necessitates an appreciation of the influence of construction techniques on performance, an estimation of the magnitude of the ground movements that will take place, and the provision of adequate strength to the structural components of the wall. In this paper, the general subject of tied-back retaining walls is considered and the results of a series of laboratory scale experiments are presented. These data provide the first comprehensive information on the subject and have enabled the basic mechanics of wall behavior to be worked out. In particular it has been shown that the performance of a tied-back retaining wall is conditioned by (1) the depth of the excavation in relation to the ground geometry, (2) the bearing capacity of the base of the wall and, (3) the interaction between the flexible support anchors (their inclination in particular), the retained ground, and the wall.The paper is divided into three parts: the first contains a brief discussion on the tied-back retaining wall with particular reference to the interaction between the anchors, the wall, and the ground; the second part is concerned with a laboratory scale test program; the third part provides a tentative interpretation of the experimental findings and draws attention to the limitation in the present understanding of the subject.