Study on determining the strength parameters of carbonate coarse-grained soils based on dynamic cone penetration tests

Carbonate coarse-grained soils are widely distributed in South China Sea. Since it is difficult to obtain undisturbed samples of coarse-grained soils, the field tests are often used to evaluate the physical and mechanical properties of coarse-grained soils. Large-scale direct shear tests on the carbonate coarse-grained soil from South China Sea were performed, and the strength parameters of carbonate gravel were obtained. The results show that based onMohr-Coulomb failure criterion, both the internal friction angle and the apparent cohesion of the carbonate coarse-grained soil are high, and that poor grade will lead to the decrement of the internal friction angle and the increment of the apparent cohesion. Indoor light dynamic cone penetration tests on the same soil were carried out, and the influences of the relative density, the average particle size and the uniform coefficient on the penetration index(Pindex) were discussed. An index named initial penetration depth, for characterizing the apparent cohesion, was proposed to establish the relationships of the penetration index with the apparent cohesion and the internal friction angle of carbonate coarse-grained soils. © 2022, Science Press. All right reserved.