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地下工程围岩承受载荷的形式为真三轴卸–加载后的扰动载荷,在频繁扰动载荷作用下围岩易出现物理力学性能劣化,进而诱发岩爆等工程灾害。基于地下工程围岩复杂受力环境,利用自制的岩石真三轴扰动诱变试验系统,开展复杂真三轴预应力路径和局部异源扰动载荷作用下花岗岩破裂试验。试验结果表明,在特定的应力状态下,在较大幅值的局部异源扰动载荷下花岗岩发生剧烈破坏,破裂模式为劈裂拉伸破坏。利用PFC3D精确再现室内试验并研究岩石扰动破裂的微观机制,研究结果表明:岩石内部的颗粒黏结从扰动载荷作用处开始破坏,当扰动载荷的幅值为150,200,250 k N时,破坏颗粒黏结数趋于稳定,最终岩石未发生整体破坏;但扰动载荷幅值等于300 k N时,破坏黏结数从施加扰动载荷位置扩散至试件整体,岩石扰动破坏由剪切破坏逐渐转变为拉伸破坏,最后发生试件整体破坏,室内试验与数值模拟结果相一致。
The load of surrounding rock in underground engineering is in the form of true triaxial unloading-disturbance load after loading, and the physical and mechanical properties are apt to deteriorate in the surrounding rock under frequent disturbing loads, so as to induce the rock burst and other engineering disasters. Based on the complex stress environment of surrounding rock in underground engineering, the self-made rock triaxial perturbation mutagenesis test system was used to carry out the test of granite fracture under the complicated true triaxial prestressing path and the local disturbance load. The experimental results show that under the condition of specific stress, the granite under severe local heterogenous perturbation load has violent damage, and the fracture mode is the splitting tensile failure. Using PFC3D to accurately reproduce the laboratory experiment and study the micro-mechanism of rock disturbance and fracture, the results show that the particle bond in the rock begins to destroy from the disturbance load. When the disturbance load amplitude is 150, 200 and 250 kN, the number of broken particles tends to And the final rock did not cause total damage. However, when the disturbance load amplitude was equal to 300 kN, the number of failure bonds diffused from the position where the disturbance was applied to the whole specimen, and the rock disturbance failure gradually changed from shear failure to tensile failure and finally occurred The whole specimen is damaged, and the indoor experiment is consistent with the numerical simulation results.