Estimation of Design Parameters for Braced Excavation in Clays

Abstract

In this study, the optimum values of the design parameters (position of struts, embedment depth of the wall, thickness of the wall and the strut stiffness) for braced excavation in clayey soil have been determined by using the numerical tool, FLAC. The design parameters are determined by studying their effects on the factors such as strut force, wall deflection, wall moment and displacement of the ground surface adjacent to the braced excavation which play significant role in the design of braced excavation. The results of the present numerical model are compared with the observed values obtained from a case study on braced excavation in a clayey soil. A close agreement between the result as obtained from the present numerical study and that measured in the field has been observed. On the basis of the parametric studies done on two different clayey soil profiles, it is found that the most effective design of excavation in a clayey soil can be done when the embedment depth of the wall, the thickness of the wall and the strut stiffness are kept within the range of (80–100)% of the depth of excavation (6–7)% of the depth of excavation and (5–25) × 105 kN/m/m, respectively. The top strut can be kept at a height of (2–3) m below the ground level without endangering the safety of the system.