Numerical optimization of the installing position for the L-shaped TPCT in a permafrost embankment based on the spatial heat control

Abstract

The traditional design of TPCTs in embankment can cause differential frost heave due to the differential cooling effect in space. To enhance the control performance of the TPCTs, we numerically evaluated the influence of installing position on the spatial heat control, including the L-shaped TPCTs at shoulders, at slopes, and at toes. The results show that: (1) the position can affect the work performance of the L-shaped TPCTs. The annual accumulated power of the L-shaped TPCT reduces from 115.0 kW at shoulder to 101.2 kW at slope in the 20th year; (2) although the embankment with L-shaped TPCTs at shoulders has the minimum net annual heat absorption of 24.7 MJ, differential temperature exists for the shallow ground; (3) the L-shaped TPCTs at slopes can both reduce the spatial temperature difference and strengthen the cooling capacity for the deep permafrost. The maximum lateral cooling distance can reach 23.0 m; and (4) the cooling depth is weakened when the L-shaped TPCTs were installed at toes. Meanwhile, its cooling effect on the center section is insufficient due to the bimodal temperature distributions. Furthermore, it can cause slightly asymmetrical temperature distribution for the deep permafrost. Therefore, the installing position of L-shaped TPCT should be considered to develop its control performance in permafrost regions.