Shear Behavior of Paris Green Clay-Concrete Interface Under Constant and Cyclic Temperature Loadings
摘要
Energy piles are subjected to daily and seasonal heating–cooling cycles, leading to cyclic expansion and contraction. These deformations can trigger changes in the thermo-mechanical behavior of the soil-pile interface. Shear behavior of the soil-pile interface can significantly affect the design and performance of energy piles. In this study, a set of direct shear tests was performed to evaluate the impact of geothermal activation on the mobilization of shear response at the interface between concrete energy piles and Paris green clay. A specially designed interface direct shear apparatus for thermo-mechanical loadings was employed. The experiments were performed under three normal stress levels of 50 kPa, 100 kPa, and 150 kPa. Constant normal load (CNL) direct shear tests were conducted for each of these normal stress levels under four different thermal loading scenarios. The first three scenarios maintained constant temperatures of 8 °C, 13 °C (reference), and 18 °C, whereas the fourth scenario involved 10 cooling–heating cycles ranging between 8 and 18 °C. The experimental interpretation of the shear behavior at the interface between saturated Paris green clay and concrete is presented and compared. Observations indicate that constant cooling (8 °C) and heating (18 °C) temperatures caused an increase in the adhesion and a reduction in the friction angle of the Paris green clay-concrete interface. In comparison, the 10 temperature cycles (8–18 °C) exerted a more limited influence on adhesion and the interface friction angle, with values remaining closer to the reference response. The results advance our understanding of the shear response of the Paris green clay-concrete interface and offer valuable insights for the design of energy piles.