软岩巷道锚注结构承载特性的时变规律与初步应用

Time-dependent laws and initial application of bearing features of bolt-grouting structure in soft rock roadway

针对软岩巷道锚注结构承载特性的时变特征,尝试将锚注结构的承载力视为时变值,并将巷道周边弹性区、塑性区以及锚注区简化为厚壁圆筒的受力分析问题,通过引入弹黏塑性本构模型,得到了锚注结构承载力的计算公式,理论分析表明:流变停止所需的锚注结构承载力以及流变量随Pb(原岩应力)与s(拉伸屈服极限)比值的增大而升高,流变特性更为显著、支护难度增加;锚注支护强度及范围的减小,导致流变停止所需的承载力以及流变量升高,是造成锚注结构失效、流变加剧的主要原因,而流变停止所需的承载力又与锚注参数密切相关,合理确定锚注参数保证流变停止时锚注结构的稳定至关重要。理论计算结果较好的反映了锚注结构承载力随流变变形增加而逐渐增大的时变规律,且与现场实测结果较为吻合,对软岩巷道锚注支护设计可起到一定的指导作用。

Regarding the time-dependent behaviors of the bolting and grouting structure in soft rock roadway, the bearing capacity of bolt-grouting structure is treated as time-dependen value, and the elastic zone, plastic zone and bolt-grouting zone around the roadway are simplified as the stress analysis problem of a thick walled cylinder. Based on an elastic-viscoplastic constitutive model, the formulas for the bearing capacity of bolt-grouting structure are attained. The results show that the needed bearing capacity of bolt-grouting structure to stop rheology and rheological convergence/deformation increases with the increase of the ratio of （original rock stress） to （Tensile yield limit）, and the more apparent the rheological features the more the support difficulty. The main reason for support failure and serious rheology is that the needed bearing capacity to stop rheology and rheological deformation increases because of the decrease of support strength and range. The value of the bearing capacity has close relationship with the bolt-grouting parameters, and it is very important that the appropriate bolt-grouting parameters can guarantee the stability of the bolt-grouting structure when rheology ends. The theoretical results reflect well the time-dependent laws of bearing capacity of bolt-grouting structure increasing with the increase of the rheological deformation, and they agree with the field observations, thus playing a great role in the design of bolt-grouting support structure in soft rock roadway.