Estimation of strut forces for braced excavation in granular soils from numerical analysis and case histories

Abstract

Construction work of many projects in urban areas requires deep braced excavations, under which circumstances, appropriate design method to assure both the safety and economy of the retaining walls and supporting systems is therefore of paramount importance. For multi-propped retaining walls, Apparent Pressure Diagram (APD) method developed by Peck (1969) is commonly adopted to determine the forces acting on the struts. Unfortunately, most previous studies focused on the performance of braced excavations in soft to stiff clays, where limited publications involve braced excavations in dense sand and gravel with medium rigid walls. In this study, both 2D and 3D finite element analyses were carried out to examine the strut forces for braced excavations in granular soils. Subsequently, based on the numerical results as well as the field measurements from a number of reported case histories, empirical charts have been proposed to determine strut loads for deep excavations in granular soils with medium rigid walls.