Experimental Research on Fracture Toughness and Tensile Strength of Red Sandstone under Different Moisture Content

In order to study the variation and correlation of mode I fracture toughness and tensile strength of red sandstone under different moisture content conditions, Brazilian splitting and NSCB tests were carried out on the red sandstone specimens with moisture content of 0%, 1.63% and 3.33% respectively by using the CMT53 test loading system, and the test data obtained were fitted and analyzed. The test results show that: 1. The tensile strength and fracture toughness of red sandstone gradually decrease with the increase of moisture content, and the softening effect of water on red sandstone is obvious, with the reduction coefficients of 0.72 and 0.66, respectively. 2. With the increase of moisture content, the dispersion of tensile strength and fracture toughness of red sandstone increases. 3. The fitting formulas of water content and tensile strength and fracture toughness are obtained by data fitting, and the fitting correlation is relatively high. The piecewise function is used to describe the relationship between tensile strength and fracture toughness. It is convenient to estimate the fracture toughness of red sandstone through its tensile strength and it has a certain reference value for studying the relationship between tensile strength and fracture toughness of red sandstone.