渗流作用下深埋岩石巷道不同强度准则对比分析

强度准则的选取是否得当，会直接影响到巷道围岩的稳定性评价与控制。为了研究强度准则效应对渗流环境下深埋圆形巷道围岩稳定性的影响规律，首先对Mohr-Coulomb(MC)准则、Drucker-Prager(DP)准则、统一强度理论(UST)和Mogi-Coulomb(MO)准则等4种岩石材料常用的强度准则进行了归纳总结，得到了平面应变条件下统一形式的屈服方程;然后针对受孔隙水压力作用的深埋圆形巷道建立理想弹塑性模型，综合考虑渗流体积力、中间主应力效应、围岩的剪胀特性以及不同的塑性区弹性应变处理方式，基于弹塑性理论推导了渗流作用下的围岩应力场、位移场和塑性区半径的统一解析解，并通过具体算例对新解的多方面影响因素进行了对比分析。研究结果表明:本文所提出的新解不仅形式简洁，而且可以灵活匹配多种常用的岩石强度准则;不考虑中间主应力效应的MC准则和DP系列准则的计算结果相对保守;考虑中间主应力效应时，可优先选用外接圆DP准则和权系数为0.5的统一强度理论，谨慎选用权系数为1的统一强度理论;中间主应力对围岩强度具有区间效应，不考虑中间主应力效应的强度准则普遍偏于保守;岩土材料的剪胀特性不仅与围岩剪胀角有关，而且还与建立的塑性势函数有关;剪胀不会改变围岩的塑性区半径，但会影响塑性区的位移分布，若不考虑剪胀将会低估围岩的实际变形;不建议将塑性区的弹性应变视为常数，应当考虑塑性区应力重分布的影响，采用广义胡克定律进行分析。

Comparative analysis of different strength criteria for deep-buried rock roadway under seepage

The selection of strength criterion will directly affect the stability evaluation and control of surrounding rock.In order to study the effect of strength criterion on the surrounding rock stability of deep-buried circular roadway considering seepage,under the plane strain condition,a unified yield equation was firstly summarized for four commonly used strength criteria of rock materials,such as Mohr-Coulomb (MC) criterion,Drucker-Prager (DP) criterion,Uniform strength Theory and Mogi-Coulomb (MO) criterion.Then,an ideal elastic-plastic model was established for the deep-buried circular roadway under the action of pore water pressure.With the considerations of seepage body force,intermediate principal stress effect,dilatancy and different elastic strains in the plastic zone,the unified analytical solutions of stress field,displacement field and radius of plastic zone of surrounding rock under seepage were deduced based on the elastic-plastic theory.Finally,some comparative analyses were conducted on the various influence factors of the new solutions by a specific example.It was found that the new solutions proposed not only have the form of conciseness,but also can flexibly match various commonly used rock strength criteria.The results of MC criterion and DP criteria without considering the effect of intermediate principal stress are relatively conservative.When considering the effect of intermediate principal stress,the circumcircle DP criterion and the uniform strength theory with a weight coefficient of 0.5 can be prioritized,and the unified strength theory with a weight coefficient of 1 should be chosen carefully.Intermediate principal stress has interval effect on surrounding rock strength.The strength criteria without considering the effect of intermediate principal stress are generally conservative.The dilatancy of geomaterial is not only related to the dilatancy angle of surrounding rock,but also related to the plastic potential function.The dilatancy does not change the radius of plastic zone,but it will affect the displacement distribution of plastic zone.The actual deformation of surrounding rock will be underestimated without the consideration of dilatancy.The effect of the stress redistribution in the plastic zone should be considered,and the generalized Hook’s law should be used for the analysis,instead of regarding the elastic strain in the plastic zone as a constant.