Strength and failure characteristics of rock-like material containing single crack under freeze-thaw and uniaxial compression

The frost heaving pressure in cracks, caused by 9% volumetric expansion of freezing water, may deteriorate fractured rock. Several freeze-thaw cycles and uniaxial compressive experiments were conducted on crack-containing specimens to study the frost propagation of open cracks and uniaxial compressive strength (UCS) of these frost-cracking specimens. The experimental results show that new frost-heaving cracks initiate at the crack tip and grow along the coplanar direction firstly, then most of them turn to the short side of specimens because of boundary effect. The frost cracking of saturated rock is greatly affected by the freezing direction. If the preexisted crack is saturated before freezing, new frost-heaving cracks will appear after only 1-4 freeze-thaw cycles. However, no frost-heaving crack occurs after 20 freeze-thaw cycles if water is injected into the precooling crack after freezing, because > 8% crack ice is squeezed out of crack. Morever, the UCS of crack-containing rock-like specimens will be reduced by these new frost-heaving cracks when the inclination angle of pre-existed crack is close to the rupture angle, and the UCS increases with increasing inclination angle or decreasing crack length.