关键词: 压入式沉井, 淤泥地层, 挤土效应, CEL, 数值模拟

Abstract:

In order to investigate the soil squeezing effect induced by press-in caisson sinking in muddy ground, the mechanism of soil displacement caused by soil squeezing is analyzed, and then the coupled Eulerian-Lagrangian (CEL) method is used to simulate the process of caisson sinking based on an ultra-deep underground garage project. In this way, the soil squeezing effect of press-in caisson and its influencing factors are studied. The study results show that: (1) The ground deformation caused by sinking can be classified into 4 types, i.e. soil plug, settlement, major heave and minor heave. (2) The faster the sinking speed, the greater the vertical squeezing effect, the smaller the horizontal squeezing effect and the larger the press stress; and the soil squeezing effect is the smallest when the sinking speed is 0.2-0.3 m/d. (3) The increase in compressive modulus of soil will lead to the growth of both vertical and horizontal squeezing effects; and the soil squeezing effect is rather small when the compressive modulus is less than 2.03 MPa. (4) The isolation piles can greatly limit the soil displacement caused by soil squeezing effect, but the press stress will also increase significantly as a result. (5) To control the soil squeezing effect, it is suggested to gently press-in caisson in soft ground with high compressibility and take digging inside caisson as an auxiliary measure in harder ground.

Key words: press-in caisson, muddy ground, soil squeezing effect, CEL, numerical simulation