层状岩体动态拉伸破坏能量耗散特征及损伤机理研究

The problem of Layered rock mass dynamic has been a hotspot in civil air defense, transportation, mining and other engineering. With the rapid development of underground engineering in China, analyzing the layered rock mass tensile dynamics damage and energy consumption characteristics are inevitable issues, especially under the condition that the lack of tensile strength of rock damage and the effectively energy is far less than the total energy input during drilling and blasting processes. As closely related with the ring topic of mass dynamic tensile damage and energy consumption characteristics of layered rock, this project uses SHPB system to conduct rock impact damage experiments at various bedding plane angle thus obtaining the intensity distribution of the layered rock mass sample and the whole stress-strain curve, variation of dynamic tensile strength, failure strain, crushing degree and energy dissipation characteristics on bedding angle, strain rate and specimen size. These results attempt to reveal the influential mechanism for the damage failure mechanism and the energy law of rock at different bedding plane angle. Based on rock dynamic, statistical theory of damage mechanics, rock mass structural mechanics, portfolio model method and numerical modeling, the damage parameter and constructed rock dynamic damage evolution equation are to be established; meanwhile, the energy equation and constitutive equations are created while considering the effect of bedding surface. The above results will reveal the internal mechanisms for energy dissipation during the layered rock mass deformation and failure processes. Overall, this project can provide a theoretical support of preventing disaster of layered rock engineering with dynamic load and improving energy utilization.

人防、交通、矿业等工程中都会涉及到冲击载荷下层状岩体动力学问题。特别是在凿岩爆破过程中，存在爆破区域外岩体因层理面损伤而导致拉裂破坏以及破岩的有效能远低于总输入能等一系列问题，开展层状岩体的动态拉伸破坏能耗规律和损伤机理研究具有十分显著意义。本项目紧密围绕这一研究主题，利用SHPB实验系统，开展不同层理面倾角下岩石冲击损伤实验，获得层状岩体岩样的强度分布、全程应力-应变曲线、微观破坏形式和裂纹开展方式，分析动态拉伸强度、加载率、破碎程度、破坏形式和层理面倾角与能量耗散特征之间的规律，揭示不同层理面倾角作用下岩石冲击破坏机理和能量耗散规律。项目以冲击动力学、统计损伤力学理论、岩体结构力学、组合模型法和数值仿真等多种理论和分析方法为手段，确定损伤参量及描述方法，构建反映层理面破坏的动态拉伸损伤本构模型。本项目的研究成果将为动载荷影响下层状岩体工程灾害防治和提高能源利用率提供可靠的理论基础。

人防、交通、矿业等工程中都会涉及到冲击载荷下层状岩体动力学问题。特别是在凿岩爆破过程中，存在爆破区域外岩体因层理面损伤而导致拉裂破坏以及破岩的有效能远低于总输入能等一系列问题，开展层状岩体的动态拉伸破坏能耗规律和损伤机理研究具有十分显著意义。本项目通过RMT-150C岩石压力机、SHPB系统和高速摄像仪开展了巴西劈裂试验，研究了不同层理角度和加载率下板岩动静拉伸强度、动态拉伸能量耗散规律以及岩体破坏模式、破坏过程和破碎程度与能量耗散之间的关系。通过研究得到如下主要结论：（1）随着加载率的增加，不同层理角度下板岩动态拉伸强度和耗散能密度均呈现非线性指数增长的趋势；（2）随着加载率的提高，板岩强度各向异性系数逐渐降低，并趋近于1；当加载率超过600GPa·s-1时，拉伸强度主要受加载率的影响；加载率低于600GPa·s-1时，层状板岩的拉伸强度受角度和加载率共同影响。（3）当加载率低于395GPa·s-1时，饱水板岩的拉伸强度低于干燥板岩，岩体强度呈现饱水软化现象；当加载率高于395GPa·s-1时，饱水板岩的拉伸强度高于干燥板岩，岩体强度呈现饱水强化现象；（4）当层理角度为0°时，动态拉伸强度处于低强度区间，破坏形式为沿层理面拉伸破坏，耗散能低；当层理角度为15°、30°和45°时，动态拉伸强度处于中等强度区间，破坏形式为沿层理面剪切破坏和沿非层理面拉伸破坏，耗散能值处于沿层理和非层理破坏之间；当层理角度为60°、75°和90°时，动态拉伸强度处于高强度区间，破坏形式为沿非层理面拉伸破坏，耗散能最大。（5）随着加载率的提高，岩体耗散能密度越大，岩体吸收的能量越多，分形维数D值越大，岩体越破碎。