砂卵石地层盾构施工渣土改良试验和数值模拟分析

Improvement Experiment and Numerical Simulation Analysis of Muck of Shield Tunneling in Sandy Pebble Stratum

针对城市地铁盾构施工在穿越富水砂卵石地层时所表现出的非适应性问题,设计开展了不同含石量砂卵石和膨润土泥浆注入率下的渣土改良试验。试验结果表明:膨润土与水的最佳土水质量比为1∶10,最佳膨化时间为20 h;通过抗剪、坍落度和渗透试验,确定了20%、40%、60%和80%含石量砂卵石膨润土泥浆的最佳注入率,并将试验结果应用于工程实践。经有限元模拟分析表明,采用19%膨润土泥浆注入率处理65%~80%含石量的砂卵石地层具有较好的应用效果,能够保证隧道沉降控制在工程要求的范围之内。

In view of the inadaptability of urban metro shield tunneling in water rich sandy pebble stratum,the experiments of the muck improvement with different stone content and mud injection rate are carried out.The results show that the optimal ratio of bentonite to water is 1∶10,and the optimal expansion time is 20 h.Through the shear resistance,slump and permeability tests,the best injection rates of sandy pebble bentonite slurry with 20%,40%,60%and 80%stone content are achieved.The test results are applied to the engineering practice.By the finite element simulation analysis,19%injection rate can better manage sandy pebble stratum with 65%~80%stone content,and ensure the tunnel settlement control within the scope of engineering requirements.