地应力对岩溶裂隙含水介质渗透特性的影响

Effect of geo-stress on permeability of groundwater in karst-fractured rock mass

研究深部岩溶裂隙含水介质渗透特性和富水规律对深部矿井安全开采具有重要意义.介绍了深部岩溶裂隙形成机理和裂隙岩体渗流运动的基本规律,结合不同现场多个钻孔进行了同一岩溶裂隙含水层在不同深度处的现场地面抽水试验和不同深度处岩层的地应力测试,同时在井下不同开采标高处对同一岩溶裂隙含水层进行了大量的单孔放水试验和涌水钻孔概率统计,得到了不同深度处的地应力值、渗透系数值、富水性指标(钻孔单位涌水量)、水压值、钻孔最大涌水量值和涌水钻孔概率.结果表明:水压值和地应力值都随埋深的增大而线性增加;钻孔最大涌水量和涌水孔率都随开采深度的增加而减小.岩溶裂隙含水介质的渗透系数和钻孔单位涌水量随地应力的增加都呈负指数规律减小;地应力增加导致岩溶裂隙张开度的减小,渗透系数减小,层流侵蚀水溶解石灰岩的能力减弱,进而使得深部岩溶裂隙含水介质的富水性变弱.不同地区的深部岩溶裂隙含水介质的渗透特性随地应力(垂向应力和平均水平主应力)的增加都呈负指数递减的规律.

It is important to study the effect of geo-stress on the permeability and water abundance of deep groundwater in karst-fractured rock mass.The formation mechanism of deep karst fissure and the basic rules of seepage in fissured rock mass were proposed.The multiple drillings were constructed for field pumping tests in different depths of the same karst fractured aquifer in different mining areas and geo-stress were measured in different depths of rock mass.Meanwhile many drillings of different mining elevations,which reveal the same karst fractured aquifer,were constructed for statistical analysis of water inflowing drilling and for single-hole water-draining tests.The values of geo-stress,water permeability coefficient,water abundance（drilling inflow per unit time）,water pressure,drilling maximum water quantity and probability of water inflowing drilling were obtained.The results show that the water pressure and geo-stress increase linearly with the increasing of the buried depth.The drilling maximum water quantities and probability of water inflowing drilling decrease with the increasing of mining depth.The water abundance and permeability coefficient of groundwater in deep karst-fractured rock mass have the same negative exponential decay with the increasing of geo-stress.The increasing of geo-stress leads to reduction of karst fissures aperture which causes decreasing of permeability,thereby the water dissolution ability of laminar flow on limestone is weakened,which resulted in the decreasing of the water abundance of deep karst-fractured rock mass.The permeability of deep karst-fractured rock mass declines in the same negative exponential fashion when the geo-stress（vertical stress and average level principle stress） increase linearly in different areas.