工作面开采正断层活化规律及采动应力演化特征

发布时间：2018-08-20 17:52

【摘要】：断层是煤矿开采中常见、影响较大的地质构造。断层破坏了岩层连续整体赋存状态,在其附近应力分布异常,采动效应十分突出,极易诱发动力灾害,对煤矿开采设计、安全生产等存在重大影响。本文通过理论计算、相似材料模拟试验和数值模拟方法,对上、下盘工作面过正断层开采期间的断层两盘运移规律、采动应力演化特征和断层活化规律进行研究,并通过现场微震事件进行了验证,主要研究成果如下:1)断层带切割了顶底板岩层的完整性,采动应力的阻隔效应显著,致使断层煤柱易形成较高的应力集中区;下盘向正断层推进时,存在支承应力突增点,使断层煤柱发生塑性破坏,释放大量弹性能;上盘向正断层推进时,支承应力平缓增加,且推进过程中部分应力能够向下盘转移。相比上盘开采,下盘开采时断层附近基本顶不易形成稳定铰接结构,向对盘传递载荷的能力弱,断层阻隔作用相对较强,断层煤柱内支承应力存在突增现象。2)断层面应力变化具有明显的时空特性。高位断层更容易受采动影响,断层面应力状态首先发生改变。同一层位断层面上,剪应力与法向应力受采动影响的敏感性不同,法向应力最先受到影响,随后剪应力发生改变。3)由数值模拟和相似材料模拟可知,下盘工作面过正断层前后30m,断层活化危险性最大,两盘覆岩运动最剧烈,过断层期间下盘易沿断层面整体滑移,过断层后20-30m期间上盘悬臂基本顶易整体切落。上盘工作面过断层期间及过断层后20m范围内断层活化的危险性最大,过断层后70m范围内两盘覆岩运动最剧烈,直接顶和基本顶随采随冒,由工作面煤壁斜向断层周期性形成破断线,切割下盘岩层,形成三角岩体,整体沉降。4)随工作面向断层推进,高位断层首先受采动影响,而后在垂直方向上向断层两端扩展。相比上盘开采,下盘工作面采动应力存在突增点,断层活化启动时间较早,断层活化期间两盘运动更剧烈,活化危险性和危害性更大。5)断层倾角、采高对煤壁前方采动应力和断层活化影响较大,断层落差影响较小。
[Abstract]:Fault is a common and influential geological structure in coal mining.Fault destroys the continuous and integral state of rock strata,abnormal stress distribution near it,mining effect is very prominent,it is very easy to induce dynamic disasters,and has a great influence on coal mining design and safety production.This paper presents theoretical calculation,analog material simulation test and numerical simulation. The numerical simulation method is used to study the migration law of the two sides of the fault, the evolutionary characteristics of mining stress and the law of fault activation during the mining of the normal faults in the upper and lower faces. The main results are verified by the field microseismic events. The main research results are as follows: 1) The fault zone cuts the integrity of the roof and floor strata, and the barrier effect of mining stress is remarkable. It is easy to form a high stress concentration area of the fault coal pillar; when the footwall is advancing toward the normal fault, there is a sudden increase in the supporting stress, which causes the plastic failure of the fault coal pillar and releases a large amount of elastic energy; when the footwall is advancing toward the normal fault, the supporting stress increases gently, and part of the stress can be transferred to the downwall during the advancing process. It is difficult to form stable articulated structure near the fault during mining, the ability of transmitting load to the wall is weak, the fault barrier effect is relatively strong, and the abutment stress in the coal pillar of the fault increases abruptly. 2) The stress change of the fault plane has obvious space-time characteristics. On the same fault plane, the sensitivity of shear stress and normal stress affected by mining is different. Normal stress is first affected, then shear stress changes. 3) According to numerical simulation and similar material simulation, the danger of fault activation is the greatest before and after the normal fault is crossed in the lower face, and the movement of overlying rock in the two sides is the most violent. Panyi slips along the fault plane as a whole, and the basic roof of the hanging wall is easy to fall down during the period of 20-30 m after passing the fault. With the working face advancing toward the fault, the high-level fault is first affected by mining, and then propagates toward both ends of the fault in the vertical direction. Compared with the upper wall mining, the mining stress of the lower wall face has a sudden increase point, the activation time of the fault is earlier, and the activation period of the fault is two. 5) Fault dip angle and mining height have greater influence on mining stress and fault activation in front of coal wall, and the influence of fault drop is smaller.
【学位授予单位】：山东科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TD82

【参考文献】