平行裂隙群岩体强度与破裂特征的试验研究

STRENGTH AND FRACTURE CHARACTERISTIC OF ROCK MASS CONTAINING PARALLEL FISSURES

为考察含平行裂隙群岩体的强度特征及裂纹扩展规律,结合数字照相量测系统,对不同裂隙倾角下类岩石试样进行了单轴压缩试验。试验结果表明,受裂隙群的影响,试样的力学参数发生一定的劣化,峰值应力和弹性模量的劣化程度分别在10.84%~35.62%和9.79%~54.17%;随着裂隙倾角的逐渐增大,试样峰值应力呈现出先减小后增大的'U'型变化特征,?为45°时达到最小值。试样破裂形式与裂隙倾角?密切相关,?为15°和30°时,次生裂纹以倾斜裂纹和中部裂纹扩展为主,试样失稳破坏模式主要由倾斜裂纹主导;而?为45°、60°和75°时,次生裂纹主要为翼裂纹和共面裂纹,且试样失稳破裂模式主要取决于共面裂纹。

In order to investigate the strength characteristic and crack extension law of rock mass containing parallel fissures, uniaxial compression tests of rock-like samples with different fissure angles were conducted combined with the digital photography measurement system. The results show that the degradation of peak strength and elastic modulus of samples is about 10.84%~35.62% and 9.79%~54.17% respectively with the effect of preset fissures. With the increase of the fissure angle, the peak strength of samples decreases first and then increases, forming a typical characteristic of 'U' type, and it reaches the minimum value as θ is 45°. The failure form is closely related to the fissure angle. The extending types of secondary cracks are mainly inclined cracks and central cracks when the joint angle is 15° or 30°, and the final instability fracture mode is due to the inclined cracks. However, when the joint angle is 45°, 60° or 75°, the extending types of secondary cracks are mainly wing cracks and coplanar cracks, and the final instability fracture mode mainly depends on the coplanar cracks.