考虑空间和锚固效应的硐室围岩弹塑性分析

为研究圆形硐室围岩在开挖-支护过程中的力学机制,根据围岩力学特征将围岩划分为弹性区、软化区及残余区,考虑围岩软化、扩容和空间、锚固效应,引入软化模量、扩容系数和剪胀角,推出了围岩弹塑性区应力、位移和范围的解析表达式。通过算例分析了不同因素对塑性区范围、应力和硐室周边位移的影响。结果表明:对于软化模量较大的围岩,锚固效应可有效地减小塑性区半径和位移;而考虑空间效应时,当开挖面到计算面的距离x值越小,围岩应力、位移越大,当x值大于10 m时,空间效应基本失效;锚固残余区扩容系数h3对硐室周边位移的影响大于锚固软化区扩容系数h2;根据不同长度锚杆支护下的硐室周边位移为支护结构围岩预留变形量设计提供了参考。

Elasto-plastic analysis of chamber rock considering spatial effect and anchorage mechanical effect

In order to study the mechanical mechanism of chamber surrounding rock in the process of excavation-supporting, the circular chamber was divided into elastic zone,plastic softening zone and plastic residual zone in accordance with mechanical characteristics of surrounding rock. The surrounding rock softening,dilatation,spatial effect and anchorage mechanical effect were considered and the softening modulus of strength parameters,coefficients of dilatancy and dilatation angle were introduced. The analytical solutions of elastoplastic stress,displacement and plastic zone radius were obtained. In addition,an example was analyzed to study the effect of different factors on the stress of plastic zone,surrounding displacement and plastic zone radius of chamber. The results show that anchorage mechanical effect can decrease plastic range and plastic zone radius for the large softening modulus of surrounding rock. While considering spatial effect when the shorter distance from excavation face to supporting face named value of x is,the bigger stress and displacement are and when value of x is greater than 10 m,the spatial effect is fail basically. Dilatancy coefficient h3 has a more important influence than h2 for surrounding displacement. Surrounding displacement of chamber under anchor bolt of different lengths can provide reference for the reserved rock deformation of supporting structure. The study in this paper can provide a theoretical basis for excavation-supporting of chamber.