关键词: 盾构, 富水砂层, 近距离下穿, 数值模拟, 停机, 沉降控制

Abstract: This paper presents a case history of a shielded tunnel of Nanjing Metro Line 7 from Gaomiao Road Station to Yongchu Road Station crossing the existing transit station. The MIDAS GTS NX finite element software is used to perform the numerical simulation on the entire construction process. Based on the actual monitoring data during the construction, the influence of the shielded tunnel construction on the settlement and deformation of the existing station is analyzed. The results show that when the shielded machine is excavating in the water-rich silty sand stratum, due to the disturbance to the surrounding soils, the change of the soil stress state causes the settlement and deformation of the existing structure; The existing structure deformation and the ground surface settlement caused by the shielded construction can be effectively controlled by selecting the reasonable range of the ground reinforcement, defining the reasonable earth pressure value, reducing the downtime and other measures, and at the same time controlling the grouting effects such as shielded tail synchronous grouting, lining and ground gap grouting filling.

Key words: Shielded Tunneling, Waterrich Sandy Layer, Closely Crossing, Numerical Simulation, Shutdown, Settlement Control