Basal-heave analysis of pit-in-pit braced excavations in soft clays

Abstract Recently, the pit-in-pit braced excavations are frequently adopted in the geotechnical engineering projects in China due to the large demand of urban underground space utilization. In this study, a simplified approach for basal-heave stability analysis of pit-in-pit braced excavations in soft clays is developed based on the limit equilibrium method. The configuration of failure surfaces is obtained by using finite element method with the shear strength reduction technique. The factors of safety computed with the simplified approach are comparable to those from the finite element simulation. This simplified approach is demonstrated through a case study of pit-in-pit excavations in Shanghai.