关键词: 顶管沉井, 顶推力, 土体破坏面, 旋喷桩加固, 模型试验, 三维主动破坏体, 三维被动破坏体

Abstract:  In order to study the deformation of pipejacking caisson and its surrounding soil under jacking force, the ABAQUS software calculation model with reinforced jet grouting pile as caisson strengthening method is established, and the simulation result is analyzed and compared with practical project and the result of PLAXIS 3D software. Meanwhile, a caisson model test is carried out with the granite residual soil of Guangzhou to verify and complement the numerical simulation results. The conclusions are as follows: (1) Jet grouting pile with designed strength before excavation can effectively reduce soil collapse around the foundation pit and pit heave. (2) When the working jacking force is applied, the penetrating crack firstly appears in the front active zone, and the vertical displacement slope increases and an obvious inflection point appears; if the jacking force continues to increase, the soil displacement will increase sharply and the surface settlement will be serious.（3) For the soil at the back, under the jacking force, the tangent angle of the surface rupture line gradually increases from 0° to 45°+φ/2, resulting in the expansion of the fracture range；When the jacking force reaches 45°+φ/2, the extension of the failure range in the short axis direction is faster than that in the long axis direction；In the threedimensional space, the failure surface of the failure soil in the passive zone is elliptic in shape at the surface；The direction of the long axis of the ellipse is the direction of the pushing axis, and the passive failure body shows an elliptic wedge in the shape of a bull horn.

Key words: pipe jacking caisson, jacking force, soil failure surface, jet grouting pile reinforcement, model test, 3D active failure wedge, 3D passive failure wedge