基于滑移面夹角线性变化的盾构隧道松动土压力计算方法研究

Study on Loose Soil Pressure Calculation of Shield Tunnel Based on Linear Change of the Included Angle of Slip Surface

基于滑移面形态随相对位移的变化而变化,并考虑盾构隧道不同地层损失下土拱演化过程,提出滑移面夹角线性变化计算方法。分析极限平衡状态下受力微分方程以求解松动土压力表达式,并考虑滑移面高度随相对位移的变化以分析地层拱对边界条件的影响。通过颗粒流数值分析模拟,研究不同工况下土拱比的变化规律以验证理论计算模型的合理性。结果表明:平均竖向应力随深度的增加而增大,但增长率逐渐变小;土拱演化过程以应力恢复为主,土拱比从0.326缓慢增大至0.495;埋深比和内摩擦角越大,土拱比越小。

Given the fact that the slip surface form changes as the relative displacement changes,and with consideration of the evolution process of soil arch of shield tunnel under different ground losses,the method for calculating the linear change of included angle has been devised.The differential equation for the stress in ultimate equilibrium is analyzed in order to solve the loose soil pressure expression,and the impact of stratum arch on the boundary conditions is analyzed by considering the pattern by which the slip surface height changes as the relative displacement changes.The particle flow numerical analysis simulation has been conducted to investigate the variation pattern of soil-arch ratio in different cases and thus verify the rationality of the theoretical calculation model.As the study indicates:Average vertical stress increases as depth increases,but the increase rate gradually decreases;the soil arch evolution process is dominated by stress restoration,soil-arch ratio slowly increases from 0.326 to 0.495;bigger buried depth ratio and internal friction angle entail smaller soil-arch ratio.