开采沉陷中不同断层活化模式研究

当工作面上覆岩层中含有断层时,地表下沉规律与不含断层时具有显著差别。为了研究开采沉陷中断层活化机理,通过理论推导将开采沉陷中断层活化分为"断层面产生离层空间"、"煤柱压缩"两种断层活化模式并分别利用数值模拟和现场实例进行了验证。研究结果表明:①采动将造成断层面产生离层空间,离层空间以下沉系数等于1传递给松散层造成断层露头处地表产生台阶下沉,影响断层离层空间的主要因素有工作面推进长度、基岩厚度、保护煤柱宽度、煤层厚度、断层倾角、断层是否含水、断层带岩体内摩擦角及黏聚力等;②断层面离层空间随着工作面推进长度的增加而增加,当工作面推进一定长度时不再变化;断层面离层空间随着基岩厚度的增加而线性增加;断层面离层空间随着保护煤柱宽度增加而减小;断层面离层空间随煤层厚度增加而线性增加;断层面离层空间随断层倾角增大而增加;断层带岩体原生水的存在对断层面离层空间产生具有促进作用;断层面离层空间随断层带岩体黏聚力和内摩擦角的增加而减小;③工作面主要影响角和断层倾角的大小关系控制"断层面产生离层空间"模式断层活化,当断层倾角大于主要影响角并与主要影响角在基岩内相交时,断层将活化;④当断层倾角小于主要影响角时,工作面超前支承压力影响范围控制"煤柱压缩"模式断层活化,当工作面超前支承压力接触断层时,断层将活化。

Different fault activation models in mining subsidence

When a fault exists in overburden strata,the laws of surface subsidence caused by mining would be greatly different from that without faults. To study the mechanism of fault activation in mining subsidence,it is divided into two different kinds of model,which are respectively the separation zone along fault plane and the coal pillar compression. At the same time,the two kinds of fault activation model are verified by numerical simulation and field example. The results show that the fault will produce separation space and the space will be transmitted to loose layer with subsidence coefficient equal to 1,which result in step subsidence at outcrop,and the influencing factors are working face advancing length,bedrock thickness,coal pillar width,coal seam height,fault dip,water in fault zone,and rock mass properties including cohesion and internal friction angle. Fault separation space will increase with working face advancing length and the increase will stop when working face advance length reach a limit. At the same time,the fault separation space will increase with bedrock thickness,coal seam height and fault dip angle,while it will decrease when coal pillar width,cohesion and friction angle of fault zone rock mass increases. Simultaneously,the fault activation model of separation space along fault plane is decided by the relationship between fault dip and influence angle and the fault will be activated when the fault angle is larger than influence angle and they intersect in bedrock. When the fault angle is smaller than influence angle,the activation model of coal pillar compression is controlled by advancing abutment pressure and it will be activated when the advancing abutment pressure reaches the fault.