Experimental study on progressive failure properties of weak and fractured rock slopes with different anchoring modes

Cutting slopes in weak and fractured rock mass will inevitably induce excessive stress or deformation of the surrounding rock, which may result in slope collapse accidents. Therefore, a large number of anchor bolts are required to reinforce the rock mass. In order to further understand the failure mechanism and the anchoring effect of this kind of slope, the weak and fractured rock mass of grade Ⅳ, according to China's classification, is taken as the reference prototype. It is equivalent to be isotropic continual stratum for facilitating research firstly, and then its geologic model ground is manufactured according to the similarity theory. Subsequently, a series of model tests are carried out to study failure characteristics of the rock slope with or without bolt reinforcement. The test results show that, if no reinforcement measures are taken, the collapse of slope is the combined results of tension failure at the top and compression-shearing failure at the bottom of the slope, and it often presents the characteristics of progressive failure. If bolts are adopted for reinforcement, on the one hand, it can effectively improve the bearing capacity and deformation resistance of rock mass, and the anchoring effect of the bolts is mainly reflected by the aspects of shear resistance, crack resistance and anti-extension; on the other hand, different bolt diameters, lengths and spacings have a great impact on the reinforcement effect and the final failure mode of the rock slope.