裂隙倾角及数目对岩体强度和破坏模式的影响

为研究不同裂隙倾角和数目下低强度岩体强度和变形破坏特征,对含不同预制裂隙的类岩石材料试件进行常规单轴压缩试验。结果表明:(1)低强度岩体峰值强度随裂隙数目增加而减小,随裂隙倾角增大而增大,裂隙倾角0°的三裂隙试件单轴压缩强度最低;(2)除90°裂隙试件外,随裂隙数量增加,试件弹性模量减小,而轴向峰值应变先增大后减小;(3)随裂隙倾角增大,试件弹性模量和轴向峰值应变总体呈“凹型”变化,最小值发生在30°裂隙试件,且大倾角裂隙试件(α>45°)的轴向峰值应变对裂隙倾角敏感程度大于小倾角裂隙试件(α<45°);(4)随裂隙数目增加,低强度岩体的破坏模式变化趋势:脆性破坏→塑性破坏→塑性流动变形破坏。

Effect of Fracture Dip Angle and Number on Mechanical Properties and Failure Modes of Rock Mass

In order to study the variation of strength and deformation characteristics of low strength rock mass with different slit angle and number of fissures, a uniaxial compression test of rock model specimens containing prefabricated cracks was carried out. The results show that (1) the peak strength of the low-strength rock mass decreases with the increase of the number of fractures, and the overall strength increases with the increase of the fracture angle. The peak strength of the multi fracture specimen with the slit angle of 0° is the lowest. (2) As the number of cracks increases, the elastic modulus of specimens at the same dip angle decreases except for 90° crack specimens, and the axial peak strain increases first and then decreases. (3) With the increase of the fracture angle, the elastic modulus and the axial peak strain have a “concave” trend, and the minimum value occurred at 30° crack specimens. The axial peak strain of the large inclination crack specimen (α >45°) is more sensitive to the crack inclination than the small dip angle fracture specimen (α <45°). (4)As the number of cracks increases, the failure modes of specimens are: brittle failure, plastic failure, plastic flow deformation and failure.