富水砂层盾构脱困降水方案设计与效果分析

Design of Dewatering Plan for Trapped Shield in Water-Rich Sand Stratum and Its Effect Analysis

深圳某地铁隧道盾构过富水砂层加固区时被困,为使盾构脱困,现场采用在盾构机四周施作三轴搅拌桩止水帷幕,而后在帷幕内或外布设降水井降水,待水位降到盾构机底部时,人工进舱清理的工法。通过降水理论计算,得出了帷幕内、外降水的涌水量和影响半径、降水井的布设数量和间距以及由于降水引起的地表沉降等参数,初步制定了较为合理的降水井布设方案,并在此基础上进行数值模拟分析,进一步确认了降水井布设方案的合理性及可行性。现场施工的成功实践表明,采用理论计算与数值模拟相结合的方法进行盾构脱困降水设计非常有效,可为类似工程提供借鉴或参考。

In order to release the shield trapped in the consolidated water-rich sand stratum in a Shenzhen subway tunnel, tile waterproof curtain by three-axis mixing piles was used to surround the shield in construction site, and tile dewatering wells were laid out inside and outside the curtain for drainage. When the water level is down to the bottom of the shield machine, the chamber would be cleaned by hand. The theoretical dewatering arithmetic was used to calculate parameters such as the water inflow due to dewatering inside and outside the curtain and its influence radius, the number and spacing of dewatering wells, as well as the surface subsidenee induced by drainage. Based on the relative reasonable initial design scheme of dewatering wells, a numerical simulation was carried out for turther confirmation of the rationality and feasibility of the design scheme. The successful practice at site shows that it is w;ry effctive to dewater and release the trapped shield by the method combining theoretical arithmetic and numerical simulation, providing a reference to similar projects.