大断面矩形巷道采动条件下过断层组破碎带研究

Study on fracture zone of cross fault group in large section rectangular roadway under mining conditions

为了使长平矿4310工作面矩形巷道在动载荷影响下能够安全快速的通过断层组破碎带,以及保持后期回采过程中巷道的稳定,在对断层受力分析的基础上,研究了工作面回采中的矿山压力与正断层上盘正应力之间的关系,并运用岩体超低摩擦效应理论和动载应力波理论研究了动载荷对断层破碎带的影响,并提出了巷道过断层的相应安全措施。研究结果表明:正断层上盘作用于下盘的正应力与回采产生的矿山压力相互作用形成应力集中导致破碎带多次扩展,动载荷使破碎带岩体失稳且造成塑性区损伤破坏;在断层破碎带采用超前预注浆改善岩性后,巷道以挖底的形式穿过正断层破碎带,使较低的应力作用于破碎围岩且使巷道穿过较小破碎带;加强支护以主被动联合支护为核心,在注浆加锚网带支护的基础上,施以合理的金属支架缓冲载荷、提高围岩强度;其底抽三巷3个断层加强支护范围分别为40、40、50 m,回采巷道见破碎发育支护即可。

Dynamic stress could cause safety issues for rectangular roadway when passing through facture zones of fault groups.The stability of roadways could also be affected under mining conditions.This paper presents a case study of a fracture zone of cross fault group on No.4310 working face of Changping Mine.The relationship between mine pressure and positive stress on the upper plate of normal fault was analyzed based on the stress analysis of faults.The theory of ultra-low friction effect on rock mass and the theory of dynamic stress wave were applied to explore the effects of dynamic stress on fault fracture zone.Then the safety measures when roadway passes through faults zone were recommended.The authors demonstrated that the stress concentration caused by the interaction between the stresses of normal fault upper plate acting on the lower plate and the mine pressure could lead to multiple expansions of the fracture zone.The dynamic stress can destabilize rocks of fracture zone and damage plastic zones.The pre-grouting method could be used to improve the lithology of fault fracture zones.Using this approach,the roadway passed through the normal fault fracture zones in the form of a dinting so that the stress applied to break surrounding rocks was lower and the fracture zone that roadway passed through was smaller.Another measure was to apply reinforced support wherever fracture was developed.The reinforced support combined active and passive supports,and applied grouting and anchoring belt and metal support to cushion the load and consolidate the strength of surrounding rocks.The ranges of the reinforced support for the three faults in the bed plate tunnel are 40,40,50 m,respectively,and the mining roadway needed to be support when the fracture was developed.