Mechanism of slurry trench wall stability in soft clay grounds

The diaphragm: wall method, by which high reliable earth-retaining walls can be constructed, is mostly adopted for excavation works on large-scale deep underground structures in soft clay grounds. It is essential to stabilize slurry trench walls, when the diaphragm wall method is adopted in soft clay grounds. Consequently, it is most significant to elucidate the ground conditions and:mechanism to establish the slurry trench wall stability. In this paper, the ground conditions and mechanism for stabilizing slurry trench walls in soft clay grounds are discussed based on the field data. The main conclusions are summarized as follows: (1) The slurry trench wall stability in soft clay grounds can be judged being based on the consolidation condition and the value of c(u)/p. (2) The lateral pressure (sum of water and earth pressures) acting on the slurry trench wall in soft clay grounds decreases from the: state at rest to the active state due to the trench wall displacement towards excavation side, followed by balancing with the slurry pressure, and that results in the slurry trench wall stability.