单裂隙花岗岩在应力–渗流–化学耦合作用下的试验研究

 通过开展单裂隙花岗岩在恒定三轴应力及化学溶液渗透压作用下的试验，对单裂隙岩石在应力–渗流–化学耦合环境下的综合响应机制进行研究。结果表明，单裂隙花岗岩在同时承受三轴压缩荷载及渗透压作用时，其侧向蠕变变形一直以稳定速率增加，显示水对裂隙面的物理软化效果，不同于完整岩石的扩容机制；应力作用下渗流溶液与裂隙表面矿物发生明显的溶解反应，其中反映硅铝酸岩矿物溶解的Al3+及SiO2浓度随时间递增，硅铝摩尔浓度比下降。扫描电镜下观察到长石、石英表面溶蚀孔洞及云母溶解后的不完整解理；随着裂隙接触面上水岩相互作用，水力开度发生变化。酸性溶液渗流情况下的水力开度降低，直至稳定；而蒸馏水渗流情况下的水力开度先增加直至稳定。造成此种不同变化规律是水岩化学反应及水力通道贯通两种因素的相互竞争的结果。对裂隙表面三维激光扫描表明，反应后裂隙面的JRC明显降低，表面趋于平缓化，表明应力作用下的溶解反应优先发展于矿物颗粒接触面。

EXPERIMENTAL RESEARCH ON MECHANO-HYDRO-CHEMICAL COUPLING OF GRANITE WITH SINGLE FRACTURE

Experiments of granite with single fracture under constant triaxial stress and chemical solution seepage are conducted，and the response mechanisms of single fracture rock to mechanico-hydro-chemical coupled condition are studied. Experimental results show that when triaxial stress and hydraulic stress are applied to the fracture spontaneously，the lateral creep deformation always increases at a constant rate. These phenomena indicate the softening effect is induced by water，which is different from the volume expansion of intact rock. Obvious dissolution between fracture surface mineral and permeant is observed，for that concentrations of Al3+and SiO2 of outlet solution increase with time. Meanwhile，according to the SEM graphs，distinct etch holes can be found at feldspar and quartz surface，and muscovite leaves uncompleted cleavage. Aperture changes with the development of water-rock interaction. Under the acid solution seepage，aperture decreases and then becomes stable. While as for distilled water seepage，aperture increases firstly，and then keeps stable. The cause for such difference is the effect competition between chemical reaction and cutting through of permeability channels. Tests of 3D laser scan of fracture surfaces denote that JRC of after-test fracture are smaller than those before test，and surfaces become smooth. Such results show the preferential dissolution occurs at mineral interface.