Empirical Method to Estimate Lateral Wall Deformation Profiles and Bending Moment in Excavation Retaining Walls

Excessive ground movements are a major concern in urban excavations because they can lead to significant displacements and rotations in adjacent structures. One of the key elements to add stiffness to an excavation support system is the retaining wall. However, it is conventionally designed based on limit equilibrium. The internal wall shear forces and bending moments are estimated employing apparent earth pressure diagrams and the internal hinge or tributary area methods. Although these approaches will prevent structural failure of the support wall, they may result in excessive wall deformations and ground movements. This paper presents an empirical method to estimate lateral wall deformation profiles and internal bending moment along a retaining wall in clays. The method is based on inclinometer data collected from 30 case histories worldwide and allows the designer, having the maximum lateral wall displacement and the height of the retaining wall, to predict the shape of lateral wall deformations for deep excavations based on soil type (i.e., based on the undrained shear strength parameter). The internal bending moment along the wall is derived from the fundamental relations of mechanics of materials and the classical theory of beams that relate the bending moment to the components of translation of the member. It assumes that the wall material is linear elastic.