一维动静组合加载下圆柱孔洞花岗岩的力学性能及破裂特征

Mechanical characteristics and fracture mechanism of cylindrical hole granite under one-dimensional coupled static-dynamic load

地应力集中和动力扰动是诱发深部岩石工程灾变的两个重要因素,开展动静组合加载下含孔洞岩石的力学特性研究能够为揭示深部岩石工程动力灾变提供参考。本文将地下巷道结构简化为含圆柱形孔洞的岩石试样,利用动静组合加载系统分别测试了不同轴向静载(σ_(s))下试样的动态力学特性,分析了σ_(s)对试样动态力学响应的影响;并对动静组合加载下圆柱孔周边的能量分布特征进行了数值模拟。结果表明:试样动态损伤总是从圆柱孔周边开始;当σ_(s)为27 MPa和36 MPa时,试样动态强度、割线模量达到最大值;试样动态损伤范围随轴向静载的增加先减小后增大,且σ_(s)大于27 MPa后,岩爆现象逐渐增强;在动静组合加载下,最大应变能密度始终出现在垂直于加载方向的圆柱孔周边。

Stress concentration and dynamic disturbance are two important factors affecting the disaster of deep rock engineering,thus the investigation of mechanical properties of rock structures under coupled static-dynamic load can provide references for revealing dynamic catastrophes in deep rock engineering.In this study,the underground roadway structure was first simplified as a rock model with a cylindrical hole,and the dynamic mechanical properties and failure modes of the cylindrical hole rock under different axial static loads(σ_(s))were tested successively by using the static and dynamic combined loading system.The effect ofσ_(s)on the dynamic mechanical response of the specimen was analyzed.Then,the energy distribution characteristics around the cylindrical hole of the specimen under coupled static-dynamic load were numerically simulated.The results show that the dynamic damage of the specimen always starts from the periphery of the cylindrical hole,and the maximum dynamic strength,secant modulus appears asσ_(s)increases to 7 MPa and 36 MPa,respectively.With the increase ofσ_(s),the dynamic damage range of the specimen first decreases and then increases,and the intensity of rockburst increases gradually whenσ_(s)is larger than 27 MPa.The maximum strain energy density always appears near the position of the cylindrical hole that is perpendicular to the loading direction ofσ_(s)and dynamic load.