初期支护对软岩隧道围岩稳定性和位移影响分析

软弱岩体隧道开挖后,围岩变形具有异常显著的流变性。基于Poyting-Thomoson模型,对隧道围岩位移进行了粘弹性解析分析,根据所得出的解析解,结合渝(重庆)沙(长沙)高速公路石龙隧道位移监控量测实践,对初期支护后隧道围岩变形特征量进行了分析对比,结果表明,理论曲线能较好地反映围岩实际位移变化特征。最后通过将支护前后围岩受力状态与单轴和三轴应力状态岩石蠕变进行类比,得知初期支护在一定程度上减小了围岩的最终变形量,可以有效地抑制隧道围岩的变形速率。其结果为确定合理的二次支护时机提供了理论依据,对同类隧道的施工支护具有很好的指导意义和较高的参考价值。

Discussion on influence of initial support to stability and deformation of surrounding rock mass in soft rock tunnel

The deformation of surrounding rock mass has prominent rheological behavior while the tunnel was excavated. The deformation of surrounding rock mass was analyzed on the basis of Poyting-Thomoson model, and the characteristics of surrounding rock mass deformation under initial support were discussed according to the universal analytical viscoelasticity solution and the monitoring results of Shilong Tunnel of Yu(Chongqing)-Sha(Changsha) Expressway. Analogy surrounding rock mass under initial support or not with rock creep under uniaxial or triaxial stress. Initial support can diminish the permanent deformation value of surrounding rock in a certain extent, and reduce the deformation rate of tunnel surrounding rock greatly. These achievements are very helpful to the determining the time of secondary lining, and have instrutional significance and referential value for similar engineerings.