Abstract：The effects of water pressure and chemical damage on the stress intensity factor of crack in rocks are analyzed，and a new fracture strength criterion of rocks with cracks under water pressure and chemical damage is put forward. This new criterion can quantitatively reflect the effects of static water pressure，dynamic water pressure or hydraulic gradient，and water-chemical damage. The effects of water on the fracture strength of rocks with cracks stem not only from static or dynamic water pressure of crack in rocks，but also from chemical damage of water on the internal friction and coherence of crack in rocks. The formula of the new fracture strength criterion of rocks with cracks is different for the two cases of close and open cracks in rocks.
