南通地铁盾构下穿既有建筑诱发基础沉降分析

针对盾构机下穿既有建筑问题，以南通地铁1号线环城东路站至中级人民法院站盾构区间下穿森大蒂花苑老旧居民区为研究对象，基于现场沉降监测，进行盾构施工对既有邻近建筑基础沉降的影响分析，针对盾构隧道下穿该老旧居民区进行数值模拟，综合考虑上部建筑荷载及盾构施工对围岩的扰动，对建筑物基础沉降进行分析。结果表明：盾构机在高富水砂土、粉土中掘进时，由于对地层的扰动和孔隙水消散等原因，易使机头扭转，造成掘进不稳定，最终引起地表沉降；而通过设置合理的土压力值，保持掘进面平衡，尽量使盾构机平稳通过，同时做好注浆、衬砌与地层间缝隙填充等工作，能够有效减小盾构引起的地表沉降。

Analysis of foundation settlement induced by shield construction of Nantong metro underpassing existing buildings

In response to the problem of shields that underpass the existing buildings, the Nantong Metro Line 1 interval, from the East Huancheng Road Station to the Intermediate People''s Court Station, which underpasses the old residential area of the Community Sendadi-Huayuan, was taken as the research case history. Based on the site settlement monitoring data, the impact of shield tunnel construction on the settlement of the adjacent buildings foundations was analyzed. Numerical simulations, taking into account the upper building load and the shield construction disturbance to the surrounding rock, were performed. The pattern of building foundation settlement was summarized. The results show that when the shield machine is tunneling in highly water-rich sandy soil and chalky soil, the head of the shield machine is prone to twisting due to soil disturbance and the dissipation of pore water, which causes instability in the excavation process and eventuallyresults in surface settlement. By setting a reasonable value of soil pressure, maintaining the balance of the digging surface, making the shield machine pass as smoothly as possible, while performing a grouting well, and filling the gap between the lining and the strata, the surface settlement caused by the shield can be effectively reduced.