花岗岩卸荷破坏机理与数值模拟研究

Essentially the excavation of rocks, rock mass of surrounding wall undergo complicated stress path with the progress of working face, display different mechanics and brittle failure characteristics in macro scale. However, current research research the rock failure mechanism with loading conditions usually, which without considering the nature of process with loading and unloading are different.The specimen of laboratory test is different, which cannot be used to repeated the different boundary conditions test, thus disturb essentially the rule analysis of unloading mechanical properties.The research focuses on the unloading mechanical property of granite of Kashgar, Xinjiang Uygur Autonomous Region, through calibration of laboratory mechanics test, the discrete element simulation test method using digital image processing, draw the correlation of micro and macro parameters, construction of unloading servo control function. The effects of unloading rate, hoop loading rate and content of mineral on the strength, deformation and failure models are studied. Through this research, the failure mechanism of surrounding wall will be revealed from the direction of unloading point, and the method of the evaluation stability of underground cavern will be improved.

地下工程开挖实质是岩体的卸荷过程，围岩随掌子面推进历经复杂卸荷应力路径，表现出不同的力学及变形响应特征和破坏模式。然而当前岩石破坏机理的研究多在加载条件下进行，没有考虑卸荷与加载过程的本质不同，特别是室内力学试验存在样本差异，单一试件无法完成多种不同边界条件下的卸荷试验，进而对卸荷破坏机理研究产生根本干扰。本项目拟以新疆喀什地区花岗岩为研究对象，通过室内力学试验实例校正，将数字图像技术融入离散元模拟中，获取微观参数与宏观参数的关系，构建卸荷伺服控制函数，研究卸荷模式变化及矿物含量等对于花岗岩强度、变形、破坏模式影响规律，最终揭示花岗岩卸荷破坏机理。通过本项目的研究，有望阐述深部地下工程围岩破坏机理，进一步提升地下洞室围岩稳定评价方法。

深埋地下工程开挖实质是岩体的卸荷过程，围岩随掌子面推进历经复杂卸荷应力路径，表现出不同的力学及变形响应特征和破坏模式，如片帮、岩爆等。然而当前岩石破坏机理的研究多在加载条件下进行，没有考虑卸荷与加载过程的本质不同，特别是室内力学试验存在样本差异，单一试件无法完成多种不同边界条件下的卸荷试验，进而对卸荷破坏机理研究产生根本干扰。项目中以新疆喀什地区花岗岩为研究对象，通过数值模拟方式获取地下洞室开挖过程中围岩所历经的应力路径变化规律的基础上，开展了大量的室内复杂应力路径下岩石力学实验。同时，通过室内力学试验实例校正，将数字图像技术融入离散元模拟中，获得了微观参数与宏观参数的关系，构建了PFC数值仿真中卸荷伺服控制函数，对卸荷模式变化与花岗岩强度、变形、破坏模式影响规律等进行了详尽地研究，并最终揭示了花岗岩卸荷破坏机理。项目研究结果可深部地下工程围岩破坏机理进行了阐述，有助于进一步提升地下洞室围岩稳定评价方法。