含尖端相交裂隙岩石的破裂特征

FRACTURE CHARACTERISTICS OF ROCK WITH TIP INTERSECTED FRACTURE

依据相似理论选取与白砂岩性质相似的模拟材料,制作含尖端相交裂隙试样并进行单轴压缩试验,分析2条相交裂隙夹角α和α角的角平分线与水平方向的夹角β对白砂岩破坏模式、力学特性的影响。采用离散元软件PFC3D对试样进行建模,模拟试样在单轴压缩下裂纹的扩展,得到了单轴压缩作用下试样的裂纹扩展特征和起裂应力变化规律。结果表明:1)随着α角的增大,试样峰值强度逐渐降低,预制裂隙内尖端裂纹发育水平逐渐提高;2)随着β角的增大,试样峰值强度逐渐提高,预制裂隙内尖端的裂纹发育水平逐渐降低;3)物理试验与数值模拟结果吻合较好,α角对起裂应力影响较大,随着α角的增大,起裂应力逐渐减小,起裂应力的大小几乎不受β角影响。

According to the similarity theory, a simulated material with similar property to white sandstone was selected. The uniaxial compression test was carried out on the specimens with tip intersected fracture. The effects of included angle of intersecting fracture α and the angle between the α bisector and the horizontal direction β on the damage modes and mechanical properties were analyzed. The specimens were modeled by discrete element software PFC3 D, and the crack propagations of the specimens under uniaxial compression were simulated. The crack propagation characteristics and cracking stresses of the specimens under uniaxial compression were obtained. The results showed that: 1) the peak intensity of the specimen decreased gradually with the increase of angle α, and the development level of the tip crack in the prefabricated crack increased gradually;2) with the increase of the angle β, the peak intensity of the specimen gradually increased, and the crack development level at the tip of the pre-formed crack gradually decreased;3) the results of numerical simulation agreed well with theoretical analysis, the cracking stress was greatly influenced by angle α. With the increase of angle α, the cracking stress gradually decreased. The size of the cracking stress was almost unaffected by angle β.