ANALYSIS OF DISINTEGRATION CHARACTERISTICS AND DISSIPATION ENERGY OF CRETACEOUS SANDSTONE UNDER HYDRATION

The Cretaceous sandstone has a short sedimentation time and a poor degree of cementation. It is easy to disintegrate under hydration. The Cretaceous Wulong Formation sandstone in Yichang, Hubei is selected to carry out laboratory static and dynamic disintegration tests. The variation law of the Cretaceous sandstone's disintegration resistance index under static and dynamic disintegration methods is analyzed. The disintegration process of Cretaceous sandstone is analyzed by measuring the change in the mass percentage of disintegrated particles in different particle size ranges after the disintegration cycle. The microscopic characteristics of the Cretaceous sandstone before and after the disintegration is observed by scanning electron microscope tests. The morphological characteristics of post-disintegration residues is analyzed for the disintegration failure mode of Cretaceous sandstone. The disintegration mechanism of Cretaceous sandstone is examined. Starting from the perspective of energy dissipation, the surface energy increment is used to quantitatively describe the process of Cretaceous sandstone disintegration degree of fragmentation. The results show that the Cretaceous sandstone under static disintegration has a lower disintegration resistance index than that of dynamic disintegration. As the number of disintegration increases, the mass percentage of small particles(0.25~0.075 mm) gradually increases, and eventually stabilizes. The disintegration of Cretaceous sandstone mainly spreads along the joint fracture surface, particle cementation surface and micro-cracks. As the particle size of the disintegrated material becomes smaller, the chance of contact with water increases, and the corresponding crack propagation path becomes shorter. The degree of disintegration is increased. The cumulative increase in surface energy can better reflect the degree of fragmentation of the Cretaceous sandstone during the disintegration process. The greater the cumulative increase in surface energy, the more broken the disintegration residue and the higher the degree of disintegration. The research results can provide a theoretical reference for the evaluation of the engineering properties of the rock and soil mass in the soft rock area.