采动诱发断层失稳的精细光学测量和连续-非连续介质力学分析方法研究及应用

Most of coal bumps or rockbursts are related to faults, reaching 60-70 percent of the total. Compared with other rockbursts, fault rockbursts (FRB) or called rockbursts induced by fault instability possess the following characteristics: a large amount of coal thrown out, serious damage and sudden occurrence, etc. In China, serious FRB take place in several coal mines, such as Qianqiu, Yuejin, Jisan, Baodian, Muchengjian, Laohutai and Wulong coal mines. With an increase of mining depth, FRB take place frequently and seriously, and many coal mines encounter incremental hazards in mining. At present, the fault instability criterion stems from experiments has not been proposed, and the effective numerical method which can be used to study the problem related to cracking of strata, movement of strata, fault instability and impact on cracked coal and rock structures is still scarce. In this proposal, based on the past studies, we attempt to develop a new digital image correlation method where a subset includes two kinds of isolated deformational modes to refinedly measure the distribution and evolution of the accumulated and liberated strain (or energy) at fault bands and nearby and the synchronistical degree of the change of displacements at different sections at a fault, and to find the fault instability criterion induced by mining. Moreover, we attempt to modify a continuous-discontinuous medium method for numerical simulation in several aspects, such as cracking of elements, assessment for unstable fault criterion and the transit from quasi-static to dynamic modes, which is preliminarily developed by Wang and coworkers, and to model a complex mechanical process that occurs in several cycles. The process is relate to several consequential stages, such as quasi-static fault deformation, fault instability, impact due to fault instability and arrest of the impact. Thus, this study can explain the mechanism and process of FRB under complex geological structures, and can provide valuable suggestions and guidelines for their predictions and preventions.

60-70%的冲击地压发生与断层有关。和其他类型冲击地压相比，断层冲击地压（FRB）具有冲击煤量大、破坏性强、发生突然等特点，千秋、跃进、济三、鲍店、木城涧、老虎台、五龙等煤矿都发生过严重的FRB。随着采深增加，FRB的频次和震级越来越大，安全生产形势严峻。目前，尚缺乏具有实验依据的断层失稳判据及采动诱发岩层开裂、运动、断层失稳及对开裂煤岩层结构冲击问题研究的有效数值方法。本项目拟在过去研究的基础上发展子区拥有两种独立变形模式的数字图像相关方法，精细探测断层带及附近的应变积累及释放规律和断层不同部位位移变化的协同化程度，获取采动诱发的断层失稳判据；通过对自主开发的连续-非连续介质力学分析方法的单元开裂、断层失稳判别方法及准静态至动态模式切换等方面的完善，实现采动下从断层准静态变形→断层失稳→冲击→冲击停止整个过程多次循环的模拟，阐明复杂构造下FRB的发生机理和过程，为其预防提供建议和指导。

断层是采矿工程中经常遇到的一种地质构造，研究采动诱发断层活化规律对安全开采具有重要意义。本项目在数值模拟、实验和算法研究方面深入开展了研究工作。在数值方面，以连续方法为工具，分别以正、逆断层上盘、下盘开采为研究对象，重点研究了断层及附近煤层应力的时空分布和断层阻隔效应；以连续-非连续方法为工具，重点研究了水平岩层变形-开裂-垮落过程及支承压力的时空分布和开采及均布载荷条件下无黏结双层叠梁变形-开裂-垮落过程。开展了剪切带精细光学测量算法研究。在基于局部位移场最小二乘拟合数字图像相关方法的剪切带应变测量、基于背景值及数字图像相关方法的土样剪切带宽度测量和修正的子区分割法及剪切带位移和应变测量等方面，取得了良好进展。以某矿为原型进行了相似材料模拟实验，并利用自主研发的数字图像相关方法计算了开采过程中断层附近的位移场以研究断层滑移规律，发现工作面与断层距离超过35m才能防止断层快速滑移。