: 为分析盾构停机期间地层变形规律,依托某富水圆砾地层地铁区间盾构工程,对盾构停机前后地层沉降变形和掘进参数变 化进行监测和研究,并计算单纯由盾体下卧层压缩引起的地层沉降。 结果表明: 盾构停机对盾体前方土体沉降变形影响更大,且 沉降速率与停机时间密切相关;盾体后方土体沉降主要受盾构掘进地层损失影响,其沉降逐渐稳定,且土层深度越浅沉降越早稳 定;对于近距离盾构下穿施工,下穿前停机造成的影响比下穿后停机造成的影响更大;盾构停机复推时由于总推力和上土舱压力大 幅增大,地层沉降曲线出现先隆起再下沉的波动,深层沉降波动幅度显著大于地表沉降,表明富水圆砾地层盾构停机会放大对邻近 深层土体的扰动影响,在盾构近距离下穿既有地下工程施工过程中应尽量避免停机。

The variations of ground settlement and shield boring parameters before and after shield stop of a metro shield section in water-rich gravel stratum are monitored and analyzed, and the ground settlement induced by shield body weight is calculated. The results indicate that: (1) The shield stop affects the settlement of the soil in front of shield body greatly, and the settlement rate is closely related to the stop time. (2) The soil settlement behind the shield body, which is mainly affected by the ground loss caused by shield construction, gradually becomes stable over time, and the shallower the depth of the soil layer, the earlier the settlement becomes stable. (3) For closely undercrossing construction of a new tunnel underneath an existing one, the impact of shield stop before undercrossing is greater than that after undercrossing. (4) Due to the large increase of the total thrust of jacks and upper pressure of the soil chamber, the ground settlement curve fluctuates first and then subsides, and the fluctuation range of deep settlement is significantly larger than that of surface settlement, which shows that shield stop in water-rich gravel stratum will amplify the disturbance effect on the adjacent deep soil, and the shield stop should be avoided as much as possible during the closely undercrossing construction.