Shear mechanical properties of limestone structural plane under hydrodynamic force-dissolution

The dissolved rock mass is widely distributed in Southwest China. Under the action of karst, the continuous deterioration of structural plane strength is one of the important factors affecting the stability of rock mass. In order to explore the evolution characteristics of structural plane under dissolution and to reveal the influences of karstification on the shear mechanical properties of limestone structural plane, based on the example of the dissolution rock slope of Jiwei Mountain in Wulong, the apparent evolution patterns of limestone structural plane and the evolution laws of shear mechanical properties as well as the deterioration mechanism of structural plane are expounded by using the indoor seepage dissolution and direct shear tests on the structural plane and the three-dimensional morphology optical scanning technology. The results show that under the dual action of chemical corrosion and physical erosion, the limestone structural plane has experienced four stages: point selective dissolution, thin groove linear stable seepage dissolution, strong dissolution of dominant pipeline flow and wall slow dissolution. During the dissolution process, the surface roughness index and dissolution rate index of limestone structural plane increase with the increase of dissolution time, and exhibit a convergence trend. During the direct shear process, the corrosion structural plane shows two-stage characteristics of the initial locking and the later shear friction and sliding, and the longer the corrosion time and the higher the stress level, the more obvious the shear hardening characteristics. With the increase of the corrosion time, the main anti-sliding structure of the structural plane develops from a rigid stable microconvex to a fine solution groove and finally evolves into a deep karst pipeline, and its ultimate shear strength shows a trend of " first decreasing, then increasing". The prediction model for shear strength of limestone dissolution structural plane is established based on the Barton's formula.