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针对光滑平行板裂隙加载渗流规律难以准确反映实际工程裂隙岩体卸荷渗流特性的问题,利用水力压裂方法制作了天然岩芯裂隙,开展了裂隙试件受轴压、围压加载和卸载作用的渗流试验,并将裂隙试件的CT扫描图像导入ABAQUS软件,对粗糙裂隙受载时的应力和变形规律进行了数值模拟。结果表明:裂隙面的法向应力是影响裂隙渗流的主要因素;在加载阶段,粗糙裂隙面受载产生接触应力致使接触部分产生变形和破坏,裂隙接触刚度增大,裂隙宽度非线性减小,渗透率降低速率越来越小;在卸载阶段,弹性变形逐步恢复,裂隙宽度缓慢增加,渗透率先缓慢增大,当载荷卸到一定值后,在孔隙压力作用下裂隙张开、渗透率突然增大。研究结果表明了粗糙裂隙与光滑平行板裂隙对载荷敏感性不同的机理,反映了实际工程裂隙岩体卸荷渗流特性。
In order to solve the problem that the seepage flow of the smooth parallel plate fissures is difficult to accurately reflect the unloading and seepage characteristics of the actual engineering fractured rock mass, the natural core fissure is produced by the hydraulic fracturing method, and the loading and unloading of the fractured specimen by axial compression and confining pressure are carried out And the CT images of the cracked specimens were imported into ABAQUS software to simulate the stress and deformation of the rough crack under loading. The results show that the normal stress of the fracture surface is the main factor affecting the seepage of fractures. During the loading phase, the contact stress generated by the load on the rough fracture surface causes deformation and failure of the contact area, increases the contact stiffness of the fracture surface and decreases the nonlinearity of the fracture width. At the unloading stage, the elastic deformation gradually recovered, the crack width increased slowly and the permeability increased slowly first. After the load unloaded to a certain value, the crack opened up under the pore pressure and the permeability suddenly increased Big. The results show that the mechanism of different load sensitivity between the rough crack and the smooth parallel plate crack reflects the unloading seepage characteristics of the actual engineering fractured rock mass.