升降温作用下裂隙演化对单裂隙花岗岩渗流特性的影响研究

Study on the Effect of Fracture Evolution on Seepage Characteristics of Granite with Single Fracture Under Heating and Cooling

为研究高温高压下粗糙单裂隙表面形貌演化特征及水力流动特性,在不同应力与渗透压条件下,开展了50~350℃升温降温循环的单裂隙渗流试验,采用三维形貌扫描技术描述不同围压下升降温作用后裂隙表面的演化特征,分析了升降温作用对单裂隙花岗岩渗流特性的影响。结果表明:单裂隙花岗岩经温度循环及渗流作用后,裂隙表面局部岩体脱落,整体轮廓高度降低,轮廓线趋于平滑;在不同应力下,升温阶段裂隙水力开度和渗透系数先减小后增大,在降温阶段,同一温度下的裂隙水力开度和渗透系数均高于升温阶段时的值;高温高压渗流作用导致裂隙表面岩体产生不可逆的热破坏,裂隙面粗糙度降低,裂隙水力开度与渗流系数因此增大。

In order to study the surface morphology evolution characteristics and hydraulic flow characteristics of rough single fracture under high temperature and high pressure,a single-fracture seepage test with heating and cooling cycles of 50-350℃under different stress and osmotic pressure conditions was carried out.Three-dimensional morphology scanning technology was used to describe the evolution characteristics of fracture surface after heating and cooling under different confining pressures,and the influence of heating and cooling on the seepage characteristics of granite with single fracture was analyzed.The results show that after the temperature cycle and seepage of the granite with single fracture,the local rock mass on the fracture surface falls off,the overall contour height decreases,and the contour line tends to be smooth.Under different stresses,the hydraulic aperture and permeability coefficient of the fracture in the heating stage decrease first and then increase.In the cooling stage,the hydraulic aperture and permeability coefficient of the fracture at the same temperature are higher than those in the heating stage.The high temperature and high pressure seepage causes irreversible thermal damage to the rock mass on the fracture surface,the roughness of the fracture surface decreases,and increasing the hydraulic aperture and permeability coefficient of the fracture.