岩爆实验过程裂纹扩展及能量转化机理研究

Rock burst is a non-linear dynamic phenomenon with an abrupt release of the energy stored in the rock mass, which always happens suddenly and may result in serious damage. Failure occurs due to the rapid transformation and release of the energy stored in the rock mass, consequently, it is necessary to study the characteristics of the energy and its transformation law during the rock burst process in order to control the occurrence of rock burst and decrease the damage owing to this disaster..With the self developed “Deep rock burst test system”, rock burst tests can be conducted on the rock samples in the laboratory with the method of traxial loading and abrupt unloading in one direction. In this research, it is planned to carry out 300 laboratory rock burst tests on various rock types including marble, granite, coal etc. During the experiments, the information including stress, strain, AE (Acoustic Emission), digital images and high speed photographs of the rock specimens will be monitored, and the methods such as image, time-frequency, crack and fragment trajectory tracing etc. will be employed to obtain the datum like the cracking and fragment ejection velocities, failure pictures, wave forms etc., and to analyze the energy characteristics and transformation law corresponding to the various periods such as loading, unloading, failure and so on; SEM (Scanning Electron Microscope) technology will be applied to study the micro-cracks of the samples before and after the tests; 3D topography of the fracture surfaces will be studied by 3D laser scanning; High speed recorded photographs of the samples will be used to analyze the crack propagation during the tests. Deformation energy, AE energy rate, surface energy of the fragments and the kinetic energy will be calculated; Mechanism of energy transformation during the rock burst process will be analyzed, thereafter, some rock burst prediction and controlling methods will be proposed..This research aims at studying the energy characteristics during the various periods of rock burst in the laboratory tests and field engineering combining many different methods like non-linear dynamics, from a perspective of energy transformation. The information including force, deformation, AE signals, crack propagation, fractal characteristics and so on will be obtained and studied in order to get a better understanding of the energy transformation law during the rock burst process.

本项目通过岩爆实验过程中试件裂纹扩展及能量转化规律分析进行岩爆机理研究。利用自主开研发的深部岩爆过程实验系统，模拟现场应力状况，进行花岗岩、大理岩、煤等在不同应力条件下的岩爆实验，采集岩爆试件在实验过程中的荷载、变形、声发射、数字照片、高速数字图像等信息，运用图像、时频、运动轨迹追踪等分析手段提取岩爆发生过程中采集到的应力、应变、速率、图像、波形等多种信息，分析岩爆实验加载、卸载、破坏等阶段对应裂纹发生及扩展特征；进行电子显微镜扫描(SEM)，分析岩样微观结构破坏前后的变化，分析判断裂纹类型及主要特征；进行三维激光扫描，获得岩爆破坏后断口表面三维形貌；分析试件表面裂纹形成及扩展特征，包括裂纹在不同阶段的扩展方向，扩展速率；计算试件应变能、岩爆破裂耗能、碎屑动能，分析岩爆过程能量转化规律，研究岩爆发生的非线性动力学机制，为工程岩爆预测预报及防治提供科学依据。

本基金项目以室内岩爆实验为基础，在实验过程中运用高速摄影、声发射和电镜扫描等观测技术手段，获取岩石试件在实验过程中的裂纹扩展等信息。基于图形图像分析，进行裂纹类型划分和特征分析，基于分形理论研究碎屑分布以及裂纹分形特征。运用双目立体视觉测量技术分析碎屑的分布规律和运动特征，定量计算岩爆碎屑动能。运用数值模拟方法模拟岩爆实验过程，进行岩爆裂纹扩展、岩爆碎屑运动和岩爆破坏进程中各阶段的不同能量形式定量计算和演化分析，得到岩爆实验过程裂纹扩展特征及能量转化基本规律。.本项目在研究过程中，将双目高速摄影手段及双目立体视觉测量技术创新性地引到岩爆实验研究之中，建立了岩爆碎屑动能测试与分析方法。从裂纹扩展和能量角度转化角度研究了岩爆试件的破坏过程，考虑了加卸载速率、外界扰动、温度条件变化等对岩爆破坏特征的影响。结合数值模拟以及微观结构分析等手段，对岩爆实验过程中岩石试件的破坏过程进行了深入分析，研究了裂纹扩展过程、碎屑特征、能量转化等关键问题，可以提高对岩爆孕育、发生、发展及致灾机理的认识，为岩爆灾害的预防和控制提供参考。