无含水层盾构始发区加固土体稳定性的有限元模拟——以苏州地铁某工程为例

A Finite-element Numerical Simulation Study of the Reinforced Soil Stability of Aquifer-free Shield Starting Zone

盾构始发端头土体加固时,如何保证加固土体的稳定性是需要解决的关键问题.结合苏州地铁某车站西端头盾构始发工程(无含水层),运用通用有限元分析软件在封门拆除这种最不利的工况下对该工程始发掘进进行了模拟分析.由数值模拟知,当纵向加固长度为3 m时,沿盾构隧道掘进方向土体向工作井内移动,最大位移发生在暴露掌子面的中心处,达12.92 mm,封门上方地表土体变形最大,沉降约为3.0 mm,强加固区范围内土体受力均在设计强度范围之内,计算出安全系数分别为2.05、1.47和1.30;在无含水层的盾构始发端头,纵向加固长度为3 m时就可以在强度上满足要求,且安全系数有富余.

Shield starting is an accident-frequent phase in th ensuring the stability of reinforced soil in this phase is a key first, frequently-adopted methods for reinforcing the soil summarized, then by combining the case of s west end in Suzhou Subway, a numerical si analysis of reinforced areas at shield start e construction of shield tunnel and and urgent problem. In this paper, at the shield tunnel ends were hield launching project （aquifer-free） of one station＇s mulation program was applied to conduct simulation ing condition--with the sealed door removed. A shafts under the most unfavorable construction ccording to numerical simulations, when thelongitudinal reinforcement length reaches 3 m, the soil shall move towards the working well in the tunneling direction of the shield tunnel, and the maximum displacement occurs in the center of exposed tunnel face, up to 12.92 m. Surface soil above the sealed door becomes deformed most, settling by approximately 3.0 m and soil within the strong reinforcement area is stressed within designed strength range, and the safety factor is 2.05, 1.47 and 1.30 respectively. At the shield starting shaft which is aquifer-free, if the longitudinal reinforcement length reaches 3 m, requirements in both strength and deformation can be met.