Shear Strength Reduction at Soil Structure Interface

Shear strength of soil-structure interface is very important while designing structures pertinent to geotechnical engineering that include but not limited to design of shallow foundation, pile, retaining wall, and sheet pile. Although the interface shear strength is very important, designers use empirical values while designing such structures. There are numerous literatures available regarding the numerically simulated values of interface shear strength. However, very few researches have been done lately on the interface resistance of different types of soil and structure. Different soil specimens were tested in a multiple-reversal direct shear device to measure the shearing resistance of soil-concrete, soil-wood, and soil-steel interface. The types of soil included in the research were SP, SW, SM, SP-SM, MH, ML, and CL, based on the USCS system. The result shows that skin resistance of soil-structure interface depends on the surface material of the structure and the type of soil. The behavior of dry soil differs from that of saturated soil.