Experimental study of interface shear characteristics between calcareous soil and steel, application to estimate axial bearing capacity of steel pile

A modified direct shear tests of interface between well-graded coral sand and coral sandy-gravel with smooth steel plate were conducted in this study under various normal stress levels. The obsevation from experimental results indicates that: (1) interface shear behavior between well-graded coral soils and steel structure follows the strain hardening rules; (2) the magnitudes of friction resistances between two materials are related to the gradation and grain size of coral soils, for coral sand limit sliding displacement is around 1mm with interface friction angle of 27.9o while for coral sandy-gravel these values are 2-3mm and 32.8o respectively; (3) interface direct shear test can be used to accurately determine friction characteristics between calcareous soil and structural material, which can effectively support analysis and design of structures built on calcareous soil.