Frost heave evaluation and prediction of high-speed railway subgrade with coarse filler in high altitude seasonal frozen region, northwest China

Abstract

The subgrade frost heave problem in high altitude seasonal frozen regions is influenced by extreme climatic conditions, geological factors, subgrade structure, and other external variables. Consequently, controlling the frost heave issue becomes challenging. Based on 8 years field monitoring of Lanzhou-Xinjiang high-speed railway (LXHR), the engineering effectiveness of current subgrade anti-frost heave measures in seasonal frozen regions is comprehensively evaluated, and long-term frost heave of subgrade is predicted. The results demonstrate that Geological conditions exert a significant influence on both subgrade frost heave and frozen depth, and the specific manifestations of frost heave are as follows: intermountain basin > Gobi desert > diluvial plain, while the frozen depths are follows: diluvial plain > Gobi desert ≈ intermountain basin. The frost heave in the middle and upper layer of the subgrade (above 1.5 m) constitutes approximately 80 %–87.5 % of the total frost heave. Considering the cumulative increase in subgrade frost heave over time, the subgrade with coarse particle material replacement, and the “two cloth and one film” technique may not be conducive to long-term stability. It is predicted that after 30 years of operation, the subgrade antifreeze layer may transition from being non-sensitive of frost heave to becoming sensitive.