Soil Conditioning Experiments for EPB Shield Tunneling in Water-Rich Sandy Cobble Strata

Based on the shield tunneling of the Chengdu Metro line 3, the soil conditioning experiment for waterrich sandy cobble strata is conducted. In light of the laboratory experiments, a reasonable mix proportion of the modifier and the optimized mixing proportion range of the foam improvement are obtained for different moisture content conditions. In a field test, the main parameters for the shield are used as indicators to evaluate the effects on soil improvement and to analyze the feasibility of soil conditioning with a foaming agent in the water-rich sandy gravel stratum dominated by slightly dense pebbles in order to ensure the quality of the soil modifier. Through a FEM numerical simulation, the laboratory and field soil conditioning test results are further verified, and the research results of the optimized mix proportion of the improvement agent and the principal excavation parameters of shield tunneling can be used as a reference for similar construction scenarios.