Parameter Optimization of Foam-Modified Silty Clay Layer Based on Response Surface Methodology

As the stratum environment of shield tunneling is becoming more complex and rich, more and more technical problems are encountered. In order to determine the optimal foam improvement parameters when excavating in silty clay for a power shield tunnel in Xi'an, a single factor test of foam injection ratio was carried out, and a regression model was established for response surface analysis to investigate the effect of the factor on the response, and the best parameters of sediment improvement were determined. The results show that the optimal silty clay improvement parameters were obtained through response surface methodology optimization: foam injection ratio of 60%, and the theoretical value of slump under the optimal improvement parameters was 118 mm, reaching the optimal fluid plasticity standard. The optimized improved parameters are applied to the shield tunneling construction, the total thrust is reduced by 1221kN, a 12% reduction, and the cutter head torque is reduced by 260kN m, a 20% reduction, and the total thrust of shield and the torque of cutter head are obviously reduced, so that the wear of cutter head is reduced and the construction speed is increased.