The Undrained Shear Behavior of Clean Coral Silt and Coral Silt-Sand Mixtures

ABSTRACT Coral silt foundation is deposited from marine land reclamation. Different soil types, including coral sand, silt, and clay with different particle diameters, are distributed in different areas through sorting and deposition. As a new type of fine-grained coral silt, the coral silt is made up of more than 50 % of particles with a grain diameter of less than 0.075 mm. This part of the fine-grained coral silt interlayer will affect the bearing capacity and cause uneven settlement of the coral silt foundation. To obtain the shear characteristics of coral silt, a series of consolidation undrained triaxial experiments were conducted on clean coral silt and coral silt-sand mixtures. The results show that the undrained behavior of coral silt displayed a strain-softening behavior. For clean coral silt, undrained peak strength and critical state shear strength were significantly dependent on the dry density. The undrained peak shear strength and critical state shear strength increase as the dry density increases. For coral silt-sand mixtures, as the coral sand content increased up to a threshold value (about 20 %), the undrained peak shear strength and critical state shear strength decreased. However, with a further increase in coral sand content, the undrained peak shear intensity and steady-state intensity began to increase.