含不同倾角裂隙砂岩渗透性能试验研究

Experimental Study on Permeability of Fractured Sandstone with Different Tips

针对西南山区水电边坡破碎岩体的渗透特性问题,以锦屏左岸边坡砂岩为例,对岩石试样预制不同倾角的人工裂隙,使用岩石高压渗透仪对其在不同围压和不同渗透压条件下的渗透特性进行试验研究,并对试验取得的渗透系数进行统计分析。试验结果表明,随着渗透压从0.1 MPa增加至0.5 MPa,裂隙砂岩亲水矿物受到溶解和冲刷作用逐渐增强从而产生新的渗流通道导致渗透系数增加。围压从2 MPa增加至4 MPa,使得岩石内部的裂隙与孔隙受到压缩闭合,导致渗透系数减小。0°、30°和45°裂隙砂岩的整体渗透系数依次减小,裂隙倾角的增加改变了裂隙渗流通道与初始渗流方向以及围压之间的夹角,还减弱了渗透系数对于围压以及渗透压的响应。

According to the seepage characteristics of fractured rock mass of hydropower slope in southwest mountainous area,and taking the sandstone at left bank slope of Jinping Hydropower Station as an example,this paper tests and studies the permeability characteristics of rock samples prefabricated with artificial fracture in different tips under different confining pressures and osmotic pressures by high pressure rock permeameter,and statistically analyzes the permeability coefficients obtained from the tests.The test results show that with the increase of osmotic pressure from 0.1 MPa to 0.5 MPa,the dissolution and scouring of hydrophilic minerals in fractured sandstone increase gradually,resulting in new seepage channels and the increase of permeability coefficient.With the increase of confining pressure from 2 MPa to 4 MPa,the fracture and pore in the rock are closed by compression,leading to the reduction of permeability coefficient.The overall permeability coefficient of fractured sandstone with tips of 0°,30°and 45°decreases in turn,and the increase of fracture dip changes the angle between fracture seepage channel,initial seepage direction and confining pressure,which weakens the response of permeability coefficient to confining pressure and osmotic pressure.