水压作用下三维裂隙组扩展过程试验研究

坝基和边坡等受压岩体裂隙中往往有水压力的存在,真实岩体中不能直接观察内部裂隙的扩展过程。自行研制了一种在低温下具有良好脆性的透明类岩石材料,内部预制张开型裂隙组,通过导管与外部高压注水设备相连进行单轴压缩试验。详细阐述了单裂隙和平行双裂隙组试件在渗透水压和单向压缩条件下内部裂纹的起裂、扩展、贯通机制;研究了裂隙组倾角及间距对平行双裂隙组试件起裂应力和峰值强度的影响。试验表明:水压作用下裂纹的扩展贯通模式和无水情况下明显不同,水压的存在对花瓣型裂纹和反翼裂纹有抑制作用,对包裹式翼裂纹有促进作用;平行双裂隙组试件的起裂应力和峰值强度随裂隙倾角增大呈现先减小后增大的趋势,并且在45°左右时强度最低;裂隙间距增加,起裂应力和峰值强度增大并逐渐趋于单裂隙强度水平。试验成果对研究岩体中水压作用下受压裂隙组起裂、贯通机制具有重要的参考价值。

The Experimental Study of Propagation Progress of 3D Crack-sets under Hydraulic Pressure

There is hydraulic pressure in fractured rock mass of dam foundation and slope under compression, and internal crack propagations in natural rock mass cannot be directly observed. A type of transparent rock-like material which had good brittleness at low temperatures was developed. Using a simple water injection device, hydraulic pressures were loaded, and uniaxial compression tests were conducted on transparent specimens built-in pre-existing elliptical open cracks. The mechanism of crack initiation, propagation and coalescence in single crack and parallel double crack-sets specimens under the combined actions of compression-shear field and seepage field was elaborated. The effect of crack angle and spacing of parallel double crack-sets on the crack initiation stress and peak strength was studied. The results showed that the mode of crack propagation and coalescence under hydraulic pressure was significantly different from that with water. The existence of water pressure had inhibitory effect on the petal crack cracks and the anti-wing cracks, the package type wing crack, while promoted wrapping wing cracks. Crack initiation stress and peak intensity of parallel double crack-sets specimens decreased first and then increased with increasing the crack angle, and got the lowest strength at about 45°. With the increase of crack spacing, the crack initiation stress and peak strength increased and tended to intensity level of single crack specimen gradually. These achievements provided a valuable guide for the analysis of the mechanism of crack-sets initiation and coalescence under pressures.