Study on the Relationship between Fracture Morphology and Splitting Strength of Granite Based on Fabric Distribution

Abstract

Because of the requirement of the mechanical properties of the damaged surrounding granite rock and the existence of the fracture water in hydraulic fracturing engineering, the strength of granite is related to the fabric, and the roughness of the section is also related to the liquid flow rate, a method of roughly determining the strength of the specimen by observing the failure mode of rock is needed. Considering that the physical and mechanical properties of granite are obviously affected by the fabric, the discrete element numerical simulation method was used to reconstruct the granite fabric based on the spatial correlation function to simulate the splitting experiment to investigate the failure mode of the specimen. The relationship between strength, the fractal value of cross-section, and the fabric was analyzed, which was verified through experiment. The results show that (1) the Voronoi GBM model with spatial correlation function of the discrete element can effectively simulate the controllable granite fabric and carry out micromechanical analysis. (2) The strength of the granite specimen and the fractal value of the cross-section have an obvious linear relationship with the fabric; besides, there is also a certain linear relationship between the strength of the specimen and the fractal value, which is influenced by granite fabric. (3) The predicted strength of the specimen according to the fractal value of the section is in good agreement with the actual strength with the error rate of 30%. In a word, this method can predict the strength of the specimen through the failure section and analyze the hydraulic fracture section and water pressure.

Experimental study on the fracture surface morphological characteristics and permeability characteristics of sandstones with different particle sizes

“…21 Du et al found that the strength of granite is related to the roughness of the section and established a method to determine the strength of specimens approximately by observing the damage pattern of the rock. 22 Chinnasamy et al investigated the effect of cryogenic treatment of rock cutting bits microstructure with different soaking time and analyzed the treatment mechanism. 23,24 Zheng et al and Tan et al conducted percolation tests on sandstone rock samples with different water saturation and studied the relationship between permeability, porosity, and stress.…”

“…Cui et al analyzed the variation law of mechanical properties and roughness properties of splitting surface of granite, and established the fitting curve between tensile strength and roughness properties 21 . Du et al found that the strength of granite is related to the roughness of the section and established a method to determine the strength of specimens approximately by observing the damage pattern of the rock 22 . Chinnasamy et al investigated the effect of cryogenic treatment of rock cutting bits microstructure with different soaking time and analyzed the treatment mechanism 23,24 .…”