盾构隧道施工土体扰动范围研究

Determination of the range of shield tunneling-induced soil disturbance

盾构隧道施工,隧道周边土体应力场发生改变,临近隧道土体因应力扰动出现塑性区,塑性区的分布范围与注浆压力、注浆量等注浆参数密切相关。塑性区被认为是施工扰动比较严重的区域,为分析盾构施工扰动范围,基于小孔扩张理论研究了注浆压力、注浆量对土体扰动塑性区的影响,推导了塑性区与注浆压力和注浆量之间的函数关系。在定义扰动评价标准基础上,提出应用有限元计算盾构施工塑性区和扰动范围的一种简捷实用的数值方法。最后采用静力触探现场测试盾构施工扰动范围,并与理论公式及有限元方法进行比较,理论公式、有限元及现场测试三者取得了较为一致的结果,验证了推荐方法的有效性。其研究结果可对盾构施工注浆参数的正确选择提供理论支持。

Due to shield tunnel construction disturbance, additional soil stresses can occur and thus soil plastic zones around tunnel may appear around the tunnel. The range of the plastic zone is closely related to grouting parameters, such as grouting pressure and grouting amount. To analyze the disturbance range caused by shield tunneling, the cavity expansion theory is introduced to determine the plastic zone and the disturbance range of the surrounding soil. The effects of backfill grouting pressure and grouting amount on the plastic zone and the range of disturbance by shield tunneling are investigated, and a functional relation between the plastic zone and grouting parameters is derived based on the cavity expansion theory. By defining a disturbance evaluation criterion, a simple numerical method for calculating the plastic zone and the disturbance range during shield construction is proposed based on the finite element method. The results obtained by theoretical formulation and finite element method are compared with the static cone penetration test（CPT） data, showing that the theoretical and numerical results are in a good agreement with those obtained by field tests, demonstrating the validity of the proposed approach. The results provide a theoretical support for the proper choice of grouting parameters in shield construction.