含石率对断层土石混合体渗流特性的影响

断层破碎带是矿山突水的重要通道,大多数破碎带由土石混合体组成,其渗流特性对矿山突水的预测和防治具有重要影响。为了研究含石率对断层破碎带土石混合体渗流特性的影响,采用现场取样、实验室重塑的方法,应用 GDS 三轴试验系统研究了不同含石率土石混合体试样在不同围压和轴向压力作用下的渗透特性,并分析了渗透系数对含石率变化的敏感性;采用RFPA数值模拟方法,研究了不同含石率土石混合体试样的渗流特性和开裂破坏演化规律。研究表明:含石率越高,初始渗透系数越高,土石混合体强度也越高;土石混合体的渗透系数随围压的增大而减小,与轴压的关系可以用指数函数来描述;含石率为40%和60%时,含石率对渗透系数影响的程度最大;土石混合体渗透破坏时裂纹的扩展主要出现在块石之间的土体内,渗透系数的突变点与试样峰值强度破坏点及声发射次数最高点存在一致性。对断层破碎带土石混合体渗流特性的研究可为防治不同含石率断层区工程突水等地质灾害提供参考。

Influence of Rock Block Proportion on Seepage Characteristics of Soil-rock Mixture in Fault Zone

Fault fracture zone is an important channel for mine water inrush. Most of the fracture zone is composed of soil-rock mixture(SRM) whose seepage characteristics have an important influence on the prediction and prevention of mine water inrush. To investigate the impact of rock content on the seepage characteristics of SRM in fault fracture zone,SRM samples were remolded in lab from the field-collected mixture of fault gouge and rubble. The permeability characteristics of samples with different rock block proportions were examined under different confining pressures and axial pressures by using GDS tri-axial test system,and the sensitivity of permeability coefficient to rock content change was analyzed. Moreover,the seepage characteristics,the crack propagation and failure of SRM samples with different rock-bearing rates were investigated by using RFPA. Results demonstrated that 1)higher rock content resulted in larger initial permeability coefficient and higher strength of SRM;2)the permeability coefficient reduced with the increase of confining pressure,and the relation between permeability coefficient and axial pressure can be described by exponential function;3)rock content of 40% and 60% had a largest influence on permeability coefficient;4)cracks during the seepage failure of SRM mainly propagated in the soil between the rocks;5)the sudden change point of permeability coefficient was consistent with the peak strength failure point of the sample and the highest point of acoustic emission frequency. The research results offer reference for preventing and controlling geological disasters such as engineering water inrush in fault areas with varied rock content.