Frost heave cracking and uniaxial compression failure behavior of sandstone samples containing a flaw filled with water.

The frost heave failure mechanism of fractured rock mass is a complicated problem faced by engineering construction in cold area. In this study, low temperature frost heave test and post-freezing uniaxial compression test on sandstone samples with a water-filled flaw were carried out. The frost heave cracking mode, frost heave pressure, frost heave cracking criterion and the effect of frost heave-induced cracks on post-freezing uniaxial compression failure behavior under different flaw inclination angles (0 ~ 90°) and freezing temperatures (-10~-40 °C) were investigated. Frost heave cracks initiate and extend along the coplanar direction of flaws. The frost heave damage degree decreases with the increase of flaw inclination angle. As the freezing temperature drops, the flaw cracking length first increases greatly, and then decreases, reaching the maximum at - 15 °C. The evolution of frost heave pressure can be divided into six stages: pre-freeze stage, rapid increase stage, rapid decrease stage, stable stage, slight rebound stage and dissipation stage. The peak frost heave pressure first increases and then decreases with the increase of flaw inclination angle, and reaches the maximum at 60°, and increases as the freezing temperature drops. Formulas for calculating the critical stress intensity factor K for flaw frost heave cracking are provided, considering flaw inclination angle or freezing temperature. When the flaw is within a certain range of inclination angles (45 ~ 75°), cracks under uniaxial compression will extend from the frost heave-induced cracks.