Testing and modeling of frozen clay–concrete interface behavior based on large-scale shear tests

Abstract

The shear behavior of the frozen soil−structure interface is important for accurately predicting the interface responses of structures adopted in the cold regions. The purpose of this study is to experimentally and theoretically investigate the shear behavior of frozen clay–concrete interface under engineering conditions. A large-scale direct shear apparatus with a temperature-controlled shear box is used to test the interface behavior. Test specimens consisting of a cement concrete block and frozen soil with initial water content ranging between 14.6% and 24.6% were prepared at different conditions of temperatures (15.4 to −9.8 °C), shear rates (0.03–0.9 mm min−1), and normal stresses (50–200 kPa). It is found that the peak shear strength is linear developing with increasing of normal stress, initial water content, and temperature. It increased from 67.7 to 133.3 kPa as the initial water content increased from 14.9% to 24.6% at temperature of −6.8 to −6.6 °C, and it increased from 51.2 to 80.6 kPa with temperature decreasing from 15.4 to −9.8 °C at initial water content of 14.6%–14.9%, furthermore it has a power law relationship with shear rate. The final vertical displacement increases with the decreasing temperature, and increasing initial water content. While, it is slight or could be ignored at lower shear rates (e.g. 0.03 mm min−1 and 0.15 mm min−1) and it is −0.25 mm and −0.28 mm at shear rate of 0.3 mm min−1 and 0.9 mm min−1, respectively. In addition, the evolution of vertical displacement also varies with test condition, the growth rate at beginning increases with increasing initial water content and decreasing temperature or ice content, which is because of the ice film effects the particle size. Moreover, a disturbed state concept model combined with linear and nonlinear characteristics is developed to describe the interface shear behavior. The disturbance D reflects the interface mechanical response and responds differently trend for different test conditions, increasing faster with increasing temperature and decreasing initial water content or shear rate. The testing results, including the test and model results, can be used to simulate the performance of engineered geotechnical assets such as earth dams or irrigation channels with concrete linings in cold regions.