粉砂地层盾构施工诱发地表沉降数值研究及其参数分析

Numerical Study on Surface Settlement Induced by Shield Construction in Silt Stratum and Its Parameter Analysis

隧道盾尾注浆弹性模量和土体的强度参数是影响盾构隧道开挖过程中地表变形的重要参数,优化这些参数可有效控制隧道施工期间的地表变形。本文针对沈阳地铁某工程区间盾构施工复杂工况,利用三维数值模拟和实地监测相结合的方法,研究了隧道的盾尾注浆弹性模量、土体的黏聚力和内摩擦角对均质土中地表变形的影响。结果表明:隧道掘进过程中,地表最大沉降和横向沉降槽宽度均随土体黏聚力的增加而减小;土体黏聚力的大小,对隧道拱顶处所产生的土拱形状及范围有较大影响;相比于土体的黏聚力,内摩擦角对地表的变形更为显著;基于模拟数据与监测数据的对比分析,始注浆弹性模量值不低于2 MPa时,可以有效预测地表变形。

The elastic modulus of tunnel shield tail grouting and soil strength are critical parameters that affect the surface deformation during excavation.Optimizing these parameters can effectively suppress the surface deformation during tunnel construction.In this paper,the effects of shield tail grouting elastic modulus,cohesion and internal friction angle of the soil on the ground surface deformation in homogeneous soil are investigated,aiming at the complex working conditions of shield construction in a district of Shenyang Metro project by applying a combination of three-dimensional numerical simulation and field monitoring.The results show that:in the process of tunnel excavation,the maximum settlement of the ground surface and the width of the lateral settlement trough decrease with the increase of soil cohesion;the strength of soil cohesion has a greater influence on the shape and extent of the soil arch at the tunnel vault;In addition,the internal friction angle exerts a more significant effect on the surface deformation than that of soil cohesion;based on the comparative analysis between the simulated data and the monitoring data,surface deformation can be effectively suppressed when the initial grouting elastic modulus value is no less than 2 MPa.