采空区隧道二衬受力特性模型试验与耦合分析

Model Test and Coupling Analysis of Mechanical Characteristics of Tunnel Secondary Lining under the Goaf

由于采空区地层的非连续特征,下穿隧道衬砌往往处在偏心受压的不利状态,后期运营病害相对严重。为了查清不同采空区条件下的衬砌结构受力特性,采用室内物理模型试验和基于连续非连续耦合数值模拟相结合的方法,开展了相关研究。结果表明:(1)采空区的存在会使二衬结构受到偏压荷载,远离采空区侧总体受力大于近侧,且倾角越大偏压越严重;(2)采煤层厚度、冒落带与初支距离的增大会引起围岩压力的降低,二衬内力减小,安全性提升,当采煤层厚度大于1.8 m时或冒落带与初支间距大于0.8倍隧道洞跨后,采空区对二衬安全性的影响很小;(3)喷层厚度的增加阻碍了围岩变形,引起围岩压力增加,不利于二衬受力和安全性。研究结论对于完善采空区隧道围岩压力计算理论和支护结构设计方法具有理论指导意义。

Due to the discontinuous characteristics of the strata in the goaf,the lining of the underpass tunnel is often in an unfavorable state of eccentric compression,and the later operation diseases are relatively serious.In order to find out the stress characteristics of lining structure under different goaf conditions,the indoor physical model tests and numerical simulation based on continuous discontinuous coupling were used to carry out the relevant research.The research results show that:(1)The existence of goaf makes the secondary lining structure subject to eccentric pressure load.The overall stress of the side far away from the goaf is greater than that of the near side,and the greater the inclination angle,the more serious the bias pressure is;(2)The increase of the thickness of coal seam and the distance between caving zone and initial support reduce the pressure of surrounding rock,reduce the internal force of secondary lining and improve the safety.When the thickness of coal seam is greater than 1.8 m or the distance between caving zone and initial support is greater than 0.8 times of tunnel span,the goaf has little impact on the safety of secondary lining;(3)The increase of shotcrete thickness hinders the deformation of surrounding rock and causes the increase of surrounding rock pressure,which is not conducive to the stress and safety of secondary lining.The research conclusion is of theoretical significance for improving the calculation theory of surrounding rock pressure and the design method of supporting structure of tunnel in goaf.