煤矿陷落柱突水的变形-渗流-冲蚀耦合模型及应用

为揭示煤矿陷落柱突水机理并为其突水防治提供理论依据,基于双重孔隙介质渗流理论,将陷落柱视为由岩块骨架、流体、裂隙充填物3种介质构成,分别推导了其运动控制方程,给出了裂隙演化控制方程,建立了多场耦合的陷落柱突水变形-渗流-冲蚀力学模型。结合研究矿区地质条件,运用多物理场耦合软件COMSOL Multiphysics将力学模型数值化,模拟研究了陷落柱内裂隙开度、颗粒体积浓度、涌水量等随时间的变化规律,数值再现了煤矿底板承压陷落柱突水发展的全过程。研究结果表明:(1)数值模拟得到的陷落柱涌水量曲线与实测数据吻合较好,验证了本文建立的陷落柱突水变形-渗流-冲蚀耦合模型的正确性。(2)在骨架变形-水渗流-充填物颗粒冲蚀迁移耦合作用下,陷落柱内充填物颗粒液化并迁移流失,部分裂隙不断扩展并贯通发展成为优势导水通道,导致陷落柱涌水量急剧增大并引发了突水事故。

A deformation-seepage-erosion coupling model for water outburst of Karst collapse pillar and its application

In order to reveal the water outburst mechanism of Karst collapse pillars (KCP) and provide theoretical basis for the water outburst prevention,based on the dual-porosity media seepage theory,the authors consider KCPs as three main components,i.e.solid matrix,fluid and filling material in fractures between matrix,then a mechanical model for KCP water outburst involving the processes of solid deformation,water flow,particles erosion and migration,fracture and the permeability change were presented.The seepage characteristics of KCPs were investigated by numerical simulation based on engineering practice,obtaining the variation of porosity,seepage velocity,water pressure,particles concentration as well as water inflow volume as the time.The research results indicate that (1) the water inflow of KCP obtained by numerical simulation is agreed with the field test data,which indicates the correctness of the mechanical model.(2) the particles in KCPs will be eroded and transported under the coupling effect of deformation-seepage-erosion,fractures will increase rapidly,then several main seepage channels will form and eventually cause the KCP water outburst accident.