Mechanism study on cracking of expansion rock

The weight and length of three directions of calcareous mudstone after infiltrated with water in different period of time were measured by using electronic balance and vernier caliper. The results show that the calcareous mudstone expansion strain is proportional to volume and mass water content. It was showed from the rock SEM picture that the structure of expansion rock was loose when infiltrated with water, and the intensity was also reduces. The mechanism of expansion rock cracking was studied. When the expansion stress inside of rock overtook the tensile strength or compressive strength, the rock produced craze, even disintegration.