深圳强风化砂岩地层中盾构下穿桩基的环境效应

Environmental Effects of the Shield Machine Underpassing Pile Foundations in Highly Weathered Sandstone of Shenzhen

依托深圳地铁龙岗线西延段福少区间盾构隧道施工工程,选取无桩、单桩与多桩存在条件下的三个监测断面,对盾构施工过程中的瞬时地表沉降与稳定地表沉降进行数值模拟,并与实测结果进行对比,研究桩基对盾构掘进过程引起的地表沉降的影响。结果表明:监测点距离隧道轴线的距离越近,产生的地表沉降值就越大;桩基所在位置监测点的地表沉降明显大于附近监测点,而多桩所在位置的沉降值在整个区段达到了最大值,且影响范围也更大,此外,多桩区域稳定沉降与瞬时沉降的差值也大于单桩或者无桩情况下的差值。为了防止盾构下穿桩基造成地表沉降过大、桩基失效等不良环境效应,提出了调整盾构掘进参数、跟踪注浆等施工控制措施。

Based on the shield tunneling of the Metro line 3 in Shenzhen city, the monitoring cross sections locating at the interval tunnel between Futian and Shaoniangong station were selected, and the influence of the pile foundations of the ground settlement was investigated. The results of numerical simulation and monitoring showed that with the increase of distance between monitoring sites and tunnel axis, the ground settlement gradually decreased;The ground settlement of the pile foundation locations was obviously greater than that of the nearby monitoring site, and that the settlements in multi-piles zone were the greatest in the whole section. In addition, the difference between stable settlement and immediate settlement of multiple piles zone was also greater than that of single pile or no pile. The construction controlling measures, such as adjusting tunneling parameters and tracking grouting, were put forward to avoiding to the adverse environmental effects, including the large ground settlement, pile foundation failure etc.