Study On The Effect of Bond Strength On The Failure Mode of Coarse-Grained Sandstone In Weakly Cemented Stratum

Abstract Bond strength is one of the most important parameters and can affect the macroscopic mechanical properties and the damage state of the rock to some degree. The coarse-grained sandstone with strength of less than 40 MPa was studied by the controlled variable method. The influence of parallel bond strength on the peak strength and failure mode of coarse-grained sandstone was simulated, the evolution law of peak strength and failure mode of bond strength were comprehensively analyzed. The results show that the peak strength of rock was positively correlated with the bond strength, the difference value between tensile and shear crack was negatively correlated with tensile bond strength and positively correlated with shear bond strength. Tensile-shear bond strength ratio less than 0.5, the peak strength of the rock was usually stable at the certain extreme value under a constant tensile bond strength. Tensile crack was negatively correlated with the tensile-shear bond strength ratio, shear crack was positively correlated with the tensile-shear bond strength ratio. The failure mode of coarse-grained sandstone is shear failure. The research results can be used to guide the ground control of other mine stopes or roadways with weak cementation lithology.