富水砂层盾构隧道地表沉降规律数值模拟分析

Numerical Simulation and Analysis of Surface Settlement Law of Shield Tunnel in Water-Rich Sand Layer

盾构机在密实性差、富水性和渗透性强、承载力较低的砂层中掘进时,易产生喷涌透水,并诱发地面塌陷。结合深圳市轨道交通12号线宝臣区间穿越富水砂层案例,采用有限元法对富水砂层地铁区间隧道盾构施工过程进行数值模拟,分析在不同掌子面压力下地表沉降规律,为掘进参数的选择提供指导。从施工成本的角度而言,掌子面压力主要用于平衡主动土压力,保持开挖面的稳定性,而采用掌子面压力来控制地表沉降并不可取,故推荐采用掌子面压力为225.3kPa~275.3kPa。

When shield tunneling machine is excavated in sand layer with poor compactness,water-rich and permeability,and low bearing capacity,it is easy to generate water gushing and seepage,which will induce ground collapse.Based on the case of Baochen Section of Shenzhen Rail Transit Line 12 crossing water-rich sand layer,the shield construction process of tunnel in water-rich sand layer is simulated by finite element method,and the ground settlement law under different face pressures is analyzed,which provides guidance for selection of excavation parameters.From the point of view of construction cost,the palm face pressure is mainly used to balance the active earth pressure and maintain the stability of the excavation surface,while it is not advisable to control the surface settlement by the palm face pressure.Therefore,the palm face pressure is recommended to be 225.3kPa~275.3kPa.