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掘进巷道富水型断层突水多场灾变演化规律研究

Study on multi-fields catastrophe evolution laws of water inrush from water-rich fault in excavation roadway

  • 摘要: 断层突水是威胁煤矿安全生产的重大灾害之一,断层既作为导水通道又作为突水水源的强富水型断层突水,具有隐蔽性高,危害性大的特点。为了有效地揭示这一矿井灾害现象,以弘财煤矿为典型案例,建立了流固耦合分析模型和Forchheimer非达西流、N-S紊流非线性渗流模型,利用数值模拟方法再现了开拓巷道富水型断层突水的动态过程,分析了突水灾变演化过程中应力场、位移场和渗流场的耦合演化规律,提炼了有效的突水前兆多元信息特征。研究结果表明:强富水型断层突水是在开挖扰动和断层破碎带内水压共同作用下的结果,在这一过程中,隔水层岩体内多场信息持续变化,整体上可以分为3个阶段,即采掘工作面远离断层时的初始变化阶段,接近断层时的快速变化阶段和突变阶段。突水过程中,地下水沿断层破碎带自上向下涌入巷道,径流途径中压力持续减小,流速总体增大,但在进入突水通道和巷道时,因流向改变而引起流速降低,随后再次增大,最终进入巷道后流速和压力逐渐趋于稳定。在隔水层破断诱发突水前,围岩应力持续增长后发生回跌,围岩位移平缓增长后急剧增大,在接近断层后断层带内水压明显增大,但在濒临突水前出现减小。结果有助于加深对富水性断层突水灾变演化过程的认识,也为突水前兆信息特征的确定提供科学依据。

     

    Abstract: Water inrush from faults is one of the major safety issues threatening the safety of Coal Mines. In water-rich fault inrush, the fault is both the water-inrush channel and the source for water inrush. It poses great harm to mining operation but can be very disguising. In order to better understand this major mine hazardous factor, the authors carried out a thorough study on water inrush accidents at Hongcai Coal Mine, a fluid-solid coupling analysis model and a non-Darcy Forchheimer N-S nonlinear turbulence seepage model is established. Numerical simulation is applied to reconstruct the dynamic process of water-rich fault inrush in the development roadway. The coupled evolution of stress field, displacement field, and seepage field through out the process of water inrush disaster are analyzed, and the effective multivariate information features of water inrush precursors are extracted. This study found out that water-rich fault inrush was the combining result of excavation disturbance and hydraulic pressure in the fault fracture zone. During this process, the multi-field information in the aquiclude changes continuously, which can be divided into three stages: the stage of initial change with the developing face far away from the fault, the stage of rapid change with developing face getting closer to the fault, and the stage of abrupt changes. During the process of water inrush, groundwater flows into the roadway from top to bottom along the fault fracture zone with the pressure continuously decreasing along the runoff path;And the overall trend of flow velocity is increasing with decreasing taking place as the water inrush entering the channel and roadway, before it starts increasing again, and the velocity and pressure gradually come to stabilize after water finally enters the roadway. Before the water inrush is induced in the aquiclude fault, the stress of surrounding rock undergoes continuous increasing before falling down, the displacement of surrounding rock increases sharply after a period of stable building-up; a noticeable increase in the water pressure in fault is observed as it approaching the fault, but decreases right before the water inrush is about to take place. This study helps to deepen the understanding of the evolution process of flooding caused by water inrush at the water-rich fault, and provides a scientific basis for determining the precursor characteristics of water inrush.

     

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