Experimental Research on Shear Mechanical Characteristics of Pile-Coral Sand Interface

Coral sand pile foundation engineering has attracted more and more attention in the construction of islands and reefs, and the influence of its occurrence environment on the bearing characteristics of pile foundation can not be underestimated. To study the shear mechanical properties of pile-coral sand interface in different environments, a self-developed temperature-controlled pile-soil interface triaxial test instrument was used to carry out triaxial drainage shear tests of coral sand taken from the South China Sea at different temperatures, confining pressures and salinities. The results show that the shear stress-displacement curve of the pile-coral sand interface has obvious strain softening characteristics, and the temperature has no significant effect on the surface characteristics of pile and coral sand, and the temperature has little effect on the shear characteristics of the interface between pile and coral sand. There is a linear positive correlation between the confining pressure and the shear strength of the contact surface. Under 100~300 kPa confining pressure, due to the rearrangement and fragmentation of coral sand particles in the shearing process, the friction angle of the contact surface decreases, and the residual strength occupies about 70%~80% of the peak strength, and the shear strength loss is more significant under higher confining pressure; compared with the fresh water environment, the salt water environment will weaken the shear strength of the contact surface to a certain extent.