盾构隧道开挖引起围土变形模型试验研究

Model Test Study on Deformation Law of Soil around Shield Tunnel Excavation

基于大尺度三向加载试验系统和自行设计的微型非接触式位移测量系统,开展室内模型试验,得到了隧道开挖过程中围土的卸载变形规律,并通过模拟不同土体损失率和荷载条件,得到洞周土体和地表土体的变形规律。结果表明:隧道开挖后,隧道拱顶发生沉降变形,底部产生隆起,隆起量约为顶部沉降量的3/5,左右两侧土体各向外产生位移,位移量约为拱顶沉降的1/3;随着竖向荷载的增大,隧洞拱顶沉降和底部隆起量都逐渐增大,变形速率减小,洞周土体随着隧道开挖和竖向荷载的增大,隧道拱顶高度呈非线性减小的趋势;各截面的地表横向沉降特征曲线较好的符合高斯函数分布规律。

Based on the large-scale three-dimensiona loading test system and the self-designed micro non-contact displacement measurement system,a indoor model test was carried out,and the unloading deformation law of surrounding soil during tunnel excavation was obtained,and the loss rate of different soils was simulated.Under the load condition,the influence law on the deformation of the surrounding soil and the surface soil was obtained.The results show that after tunnel excavation,the tunnel arch has settlement deformation,and the bottom has a bulge.The uplift is about 3/5 of the top settlement.The soil on the left and right sides are displaced outwards,and the displacement is about 1/3 of the top settlement;with the increase of vertical load,the tunnel arch settlement and bottom uplift are gradually increased,and the deformation rate decreases.With the tunnel excavation and vertical load increasing,the height of tunnel vault decreases nonlinearly;the characteristic curve of the surface transverse settlement of each section is in good agreement with the distribution law of Gaussian function.