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深部围岩在开挖卸载过程中表现出的峰后复杂力学特性一直是工程界十分关注的问题,深入研究岩石峰后力学行为对深部资源开采工程具有重要意义。以深部立井马头门工程为依托,通过室内试验方法研究花岗岩峰后力学特性,采用非线性拟合方法获得花岗岩峰后软化模量与围压的指数关系式,假定岩石的剪胀角为恒定值,基于塑性理论构建考虑围压及剪胀角影响的岩石峰后应变软化模型;以FLAC3D为平台开发数学模型并进行验证,通过构建马头门巷道数值模型,分析深部围岩在应变软化条件下的破坏特征规律。通过研究可知,花岗岩峰后破坏具有脆–延性转化趋势,在高围压条件下,岩石峰后表现出塑性软化破坏特征,岩石峰后软化模量随着围压的增大而减小;通过FLAC3D进行数值验证可知,构建的应变软化模型与试验数据基本吻合,所建立的应变软化模型具有较高的可靠性;通过数值模拟方法分析深部马头门巷道围岩破坏特征可知,巷道拱顶及拱脚等局部区域出现了塑性剪切应变,与现场巷道围岩破损位置及深度基本相同。
The complex post-peak mechanics characteristics of deep surrounding rock during excavation and unloading process have always been a very important issue in engineering field. It is of great significance to deeply study the mechanical behavior of post-peak rock on the exploitation of deep resources. Based on the deep vertical well Ma Tau Mun project, the mechanical properties of granite after the peak were studied by laboratory test, and the exponential relationship between the post-peak softening modulus and confining pressure of granite peak was obtained by non-linear fitting method. Assuming that the rock dilatancy angle is constant , The post-rock strain-softening model considering the effect of confining pressure and dilatancy angle was constructed based on plasticity theory. The mathematical model was developed and verified by using FLAC3D platform. By constructing the numerical model of the Matoumen roadway, Under the destruction of the characteristics of law. The results show that the post-peak granite fracture has the tendency of brittle-ductile transformation. Under high confining pressure, the plastic softening failure characteristics appear after the rock peak. The post-peak softening modulus decreases with the increase of confining pressure. FLAC3D numerical verification shows that the strain softening model is basically consistent with the experimental data, the established strain softening model has high reliability; numerical simulation method to analyze the surrounding rock characteristics of the deep Ma Toumen can be seen that the tunnel roof and Arch and other local areas appeared plastic shear strain, and the surrounding rock roadway location and depth of damage is basically the same.