CHAPTER 4

BEHAVIOUR OF DEEP EXCAVATION DURING FAILURE

4.1 Introduction

In this chapter, centrifuge tests on behaviour of deep excavation during failure are reported. In this series of tests, the centrifuge models were designed such that the excavation was vertically supported by diaphragm wall and the total excavation depth was 150 mm in model scale subjected to 100g which corresponds to a prototype scale of 15 m. This series includes five tests namely To1, To2, Ts1, Ts2 and Ts3 ( Table 3.4) where the lateral supports were different. To1 and To2 were excavations supported by a cantilever diaphragm wall. For test Ts1, the diaphragm wall is strutted near the ground level. In test Ts3, the wall was supported by an upper strut similar to Ts1 before excavation but a second strut was installed when excavation was down to 75 mm. For test Ts2, the diaphragm wall is strutted at top of the wall as in Ts1, but the total excavation depth is 50 mm instead of the 150 mm in Ts1. Due to the corruption of computer hardware, the data for tests To2 and Ts1 cannot be fully presented. In order to investigate the behaviour of deep excavation during failure, all tests in this series were carried