高应力巷道锚固复合承载体及其承载效应研究

The composite anchorage bearing structure in high stress roadway and its load-bearing effect

采用锚杆支护的巷道,锚杆和其巷道锚固范围内的浅层破碎围岩共同作用形成的具有一定承载能力的结构称为锚固复合承载体,锚杆支护主要改善了承载体内围岩应力分布状态。采用理论分析对锚固复合承载体进行研究,建立围岩-支护相互作用机制的基础。考虑高应力岩体不可压缩性,采用Levy-Mises增量型本构关系对围岩塑性进行表述,并考虑中间主应力的影响,利用修正Mohr-Coulomb强度准则进行高应力锚固巷道围岩力学分析,给出出现塑性变形时的原岩应力阈值。算例与分析的对比结果表明,基于锚固复合承载体承载效应,利用Levy-Mises本构关系修正的Mohr-Coulomb强度准则更适用于高应力场巷道围岩分析。

In roadways supported by bolting,the composite anchorage bearing body,a bearing structure with a certain carrying capacity,is formed by the combination of bolts and broken soft rocks within its anchorage range,where the bolt support improves the stress state of surrounding rock.The composite anchorage bearing body was studied through theoretical analysis,to establish the basis of the surrounding rock-support interaction mechanism.In view of the incompressibility of high stress rock mass,the plasticity of surrounding rock was described with Levy-Mises increment constitutive relation.In addition,the mechanical analysis of surrounding rock of high stress bolting roadway was conducted with modified Mohr-Coulomb strength criterion in consideration of the influence of intermediate principal stress,further delivering the original rock stress threshold when the plastic deformation occurs.The comparison between the diffset and the analysis has shown that the Mohr-Coulomb strength criterion modified by the Levy-Mises constitutive relation is more suitable for the surrounding rock analysis of high stress field roadway based on the bearing effect of composite anchorage bearing body.