考虑围岩应变强化及扩容的深埋软岩隧洞时变位移解

Time-varying Displacement Analytical Solution of Deep Soft Rock Tunnel Considering Strain-hardening and Dilatation of Surrounding Rock

为描述深埋软岩隧洞围岩时变位移受岩石应变强化与扩容协同影响的复杂力学过程,假设岩体为符合Burgers体与Drucker-Prager屈服准则组合的黏弹塑性模型,在考虑应变强化及扩容效应影响的初始应力场下,推导得到深埋软岩隧洞的黏弹塑性时变位移解析解并进行分析。结果表明:该解析解能较好地描述软岩隧洞蠕变位移受岩体应变强化和扩容的影响。随着幂强化指数或剪胀角的增大,隧洞围岩的时效变形逐渐增大,且发展变快。隧洞围岩在应变强化和扩容效应的共同影响下,幂强化指数与剪胀角越大,其位移越敏感,且幂强化指数对围岩位移的敏感性更高。为验证该解析解的实用价值,与工程实测数据进行对比,结果显示计算值与实测值吻合较好,表明该解析解对深埋软岩隧洞时变位移预测具有一定的借鉴意义。

The deformation of deep tunnels in soft rocks is a complex mechanical process under the effects of strainhardening and dilatation of surrounding rock. To describe this process,a combination model of a Burgers body with a friction plate considering Drucker-Prager criterion is used when the excavation are finished,and the surrounding rock performed as an elastoplastic material. Under this condition,the time-varying displacement analytical solution of the surrounding rock is deduced considering dilatancy for the deep tunnel in soft rock. The results show that the timedependent deformation of surrounding rock increases with the increase of power-hardening index or that of dilatancy angle. When the tunnel surrounding rock is affected by both strain-hardening effect and dilatancy effect,the powerhardening index and dilatancy angle become severer,the displacement is more sensitive,and the power-hardening index is more sensitive to the displacement of surrounding rocks. So,strain-hardening and dilatancy of soft rock influence greatly on the creep of surrounding rock. The calculated results of coincide with the actural measured data very well.