Development of Cyclic Interface Shear Test Device and Testing Procedure to Measure the Response of Cohesive Soil-Structure Interface

Abstract Cyclic loading acting on foundations supporting renewable energy systems affects the soil-structure interface properties and shear resistance. The cyclic shear stress and cyclic displacement applied to the cohesive soil-structure interface may cause volume changes and pore pressure build up in the surrounding soil. This article focuses on the development of a new testing device named the cyclic interface shear test (CIST). The CIST is a fully automated device developed to directly measure the response of cohesive soil-structure interface for foundations subjected to long-term cyclic axial loading. This article describes the newly developed testing device, including the design of the shear head and the three-dimensional (3D) printed interface elements, as well as the control system and data acquisition system. Furthermore, the article presents the sample preparation for clayey soil and the recommended testing procedure for conducting static or cyclic interface shear tests, or both. The developed CIST device is capable of applying one-way, two-way, or combined one- and two-way cycles. Furthermore, the CIST is capable of applying different amplitudes, a range of loading frequencies, and a large number of cycles. To demonstrate the capabilities of the CIST device and to finalize the testing procedure, a series of preliminary CISTs and a static baseline test on cohesive soil-3D printed interface were performed.