DISPLACEMENT CHARACTERISTICS OF FRICTION PILES EMBEDDED IN SATURATED CLAY SUBJECTED TO THERMAL CYCLES

Energy piles play a dual role in supporting the upper load and energy exchange. The bearing capacity of end-bearing piles and the deformation of friction piles under cyclic temperature are two major problems. However, there are few studies on the deformation characteristics and mechanism of friction piles in saturated clay under long-term cyclic temperature. In this study, a model test on the thermal response characteristics of a pile foundation under long-term cyclic temperature was carried out for friction piles in saturated clay. The development pattern of pile/soil temperature distribution, pore water pressure of soil surrounding the pile caused by temperature and the deformation of pile head were measured. The mechanism and variation of cumulative settlement of pile head were discussed. The results show that during a single thermal cycle, the displacement rate of the pile top under heating is slightly smaller than that of cooling. The difference in the displacement rate of the pile head between heating and cooling gradually decreases with the increase in the number of temperature cycles. Therefore, the cumulative settlement gradually stabilizes. Under the conditions of this study and long-term (20 times) cyclic temperature, the cumulative head settlement of the friction pile gradually stabilized at 2%D (D is the pile diameter).