Experimental study on cyclic behavior of gravel-structure interface with stress-control mode under constant normal stiffness

A new apparatus is developed to investigate the stress-controlled behavior of the interface between structure and gravelly soil under constant normal stiffness condition. The test results indicate that: (1) the volumetric change is induced by cyclic shear and can be divided into reversible and irreversible parts. The reversible part is governed by tangential displacement amplitude, and the irreversible part is significantly affected by shear distance; (2) the anisotropy of interface volumetric change is obviously observed and has great concern with shear paths and control modes; (3) the tangential displacement accumulates and migrates gradually with shear cycles. The shear paths and control modes have influences on the relationship between shear stress, stress ratio, normal displacement versus tangential displacement; (4) the interface shear strength is gradually mobilized after the first few shear cycles under stress control, and its friction angle is independent of the control modes.