黏土中圆形低真空隧道管片结构内力分布及其影响因素

针对盾构隧道管片结构在不同环境下的受力性能,建立基于修正惯用法的力学模型,推导出圆形低真空隧道管片结构内力的解析解;以武汉黏土作为模拟地层,分别采用修正剑桥模型和弹簧模型,模拟分析圆形低真空隧道结构的内力分布;在获得解析解和2种数值解的基础上,对比分析特定工况下3种方法得到的隧道管片结构内力分布,探讨真空力、弯曲刚度有效率、地基抗力系数、侧向土压力系数这4个关键参数的影响规律。结果表明:对于黏土中的圆形低真空隧道,顶部与底部的管片结构正弯矩较大,腰部则是轴力与负弯矩较大;真空力对管片结构的弯矩几乎没有影响,但对轴力影响非常显著,且随真空力的增大而增大;管片结构弯矩随弯曲刚度有效率的增大而增大,随地基抗力系数和侧向土压力系数增大而减小;管片结构轴力随地基抗力系数的增大而增大,随弯曲刚度有效率增大而减小;在隧道腰部附近,轴力随侧向土压力系数的增大而减小,但隧道底部和顶部附近则与之相反。对比3种方法,解析解与数值解具有较好的一致性,但求解结果偏于保守。

Internal Force Distribution and Influencing Factors for Segment Structure of Circular Low Vacuum Tunnel in Clay

According to the mechanical performance of shield tunnel segment structure in different environments,the mechanical model based on modified routine method was established,and the analytical solution for the internal force in the segment structure of circular low vacuum tunnel in clay was derived based on the routine method.Taking Wuhan clay as the simulation stratum,the modified Cam-clay model and elastic spring model was respectively used to simulate and analyze the internal force distribution in the segment structure of circular low vacuum tunnel.Based on the analytical solution and two numerical solutions,the internal force distributions of tunnel segment structure obtained by three methods under specific working conditions were compared and analyzed,and the influence laws of four key parameters such as vacuum force,bending stiffness efficiency,foundation resistance coefficient and lateral earth pressure coefficient were discussed.Results show that for the circular low vacuum tunnel in clay,the positive bending moment of the segment structure is larger at the top and bottom,while the axial force and negative bending moment are larger at the waist.The vacuum force has little effect on the bending moment of the segment structure,but it has a significant effect on the axial force,which increases with the increase of the vacuum force.The bending moment of segment structure increases with the increase of the effective rate of bending stiffness and decreases with the increase of the subgrade reaction coefficient and lateral earth pressure coefficient.The axial force of segment structure increases with the increase of subgrade reaction coefficient,and decreases with the increase of the effective rate of bending stiffness.The axial force near the waist of tunnel decreases with increase of lateral earth pressure coefficient,but it is opposite near the bottom and top of the tunnel.Compared with the three methods,the results based on the analytical solution are generally in good agreement with those obtained from numerical solution,however,the results are conservative.