基于大型动态试验的动荷载诱发卸荷煤岩体冲击地压机理研究

With the excavation depth of coal mining increasing, the disaster of rock burst is aggravated obviously and the new characteristic of it induced by dynamic load is appeared. According to this, it is studied the mechanism of rock burst in unloading coal-rock induced by dynamic load, with new thought of large size dynamic test system based on large scale specimen of unloading coal-rock , which breaking through the limit of small specimen size in SHPB. It is studied the fracture evolution law of unloading coal-rock on large scale specimen by different action mode of dynamic load. The dynamic constitutive model is established, the dynamic effect (strain rate effect, wave effect and inertial effect) is analysed, the dynamic response mechanism of unloading coal-rock by dynamic load is studied, the failure mode and the criterion of coal-rock is identified, base on large size dynamic test, multi-scale numerical simulation test, field monitoring and theoretical analysis. The unloading coal-rock induced by dynamic load is system analysis by multi-scale, which about the crack damage of meso-scale, the material deterioration of test-scale, and structural instability of macro-scale.The catastrophe model of bipartite system dynamic instability is established and the mechanism of rock burst induced by dynamic load is studied.It will improve the mechanism of rock burst, reduce the dynamic disaster and has important scientific significance.

随着煤矿采深的增加，冲击地压灾害显著加重，且出现动荷载诱发冲击地压的新特点，针对这一现象，本项目围绕动荷载诱发卸荷煤岩体冲击地压机理，突破SHPB试验中试件尺寸小的限制，提出基于大尺寸煤岩卸荷试件的大型动态试验的新思路。在大尺寸煤岩模型上模拟开挖卸荷，施加不同作用形式的动荷载，获得卸荷煤岩体的裂隙破裂演化规律；并结合多尺度数值模拟试验、现场监测和理论分析，建立动荷载下卸荷煤岩体的动态本构模型，分析卸荷煤岩体在动荷载作用下的应变率效应、波效应和惯性效应等动力效应，明确卸荷煤岩体不同动载条件下的动态响应机制，辨识煤岩体的结构失效模式，量化相应的结构失效准则；从细观尺度的裂隙损伤、实验尺度的材料劣化和宏观尺度的结构失稳，对动荷载作用下卸荷煤岩体进行多尺度的系统分析，建立煤岩两体结构系统的动力失稳突变模型，量化发生冲击地压的判据，对完善冲击地压理论，减少煤矿动力灾害的发生，具有重要的科学意义。

本项目从煤矿采掘期间动载型冲击地压发生特点入手，探讨卸荷煤岩体在不同类型载荷作用下的围岩稳定性规律，指出动载对卸荷煤岩体冲击破坏的响应形式和响应特征，得出动静耦合作用效果与单一静载或动载作用的差别；根据动载型煤矿巷道围岩破坏特点，研究了不同卸压与加压条件下卸荷煤岩体裂隙发育特点，指出卸荷煤岩体存在分区破坏特性，在此基础上探讨静态卸荷与动态卸荷对卸荷围岩的破坏特性，指出动态卸荷时间存在临界值，结合卸荷过程中力学参数的演化规律提出卸荷量变化比值，用以表征卸荷煤岩体力学参数劣化规律，进而对开挖卸荷过程中卸荷影响区进行划分；利用波形转化将现场微震波形转化为试验室加载路径，借助大型动态试验机再现大尺寸煤样动态失稳破坏的宏观力学表现，结合不同动静组合路径下声发射统计计数演化特征，建立动载作用下卸荷煤岩体损伤模型，即“卸荷-静载-动载”模型，针对静载基础上动载波形的加卸载特点，提出动载弹性能量指数与动载滞回环概念，分析动载荷作用下卸荷煤岩体能量的积聚与耗散特性，在此基础上提出卸荷煤岩体在冲击载荷作用下发生破坏的动态响应机制；结合工程尺度动载诱发卸荷煤岩体失稳特性，提出动载冲击地压的发生需要一定的静载基础，静载水平越高，动载作用下发生冲击地压的概率越大，即动载型冲击地压的量化判据，进一步指出动载诱发卸荷煤岩体失稳主要体现在“多重损伤-动态扰动”的演化过程。