Treatment Technology and Engineering Application of Settlement Distress in Permafrost Subgrades in Alpine Regions of Tibet

Chaoping Li

doi:10.63313/FE.9012

Authors

Chaoping Li Lhasa Municipality Design Group Co.,Ltd, Lhasa, Xizang, 851414, China Author

DOI:

https://doi.org/10.63313/FE.9012

Keywords:

Alpine regions of Tibet, frozen-soil subgrade, settlement distress, synergistic treatment, thermal insulation, engineering application

Abstract

Permafrost and seasonal frozen soils are widely distributed in the alpine regions of Tibet. Under the combined effects of climate warming and engineering disturbances, the thermal stability of frozen ground has continuously deteriorated, resulting in increasingly severe pavement and subgrade distresses, including subgrade settlement, pavement cracking, and shoulder deformation, which significantly threaten highway operational safety and service performance. Existing studies have primarily focused on the mechanisms of frozen-subgrade distress formation and individual treatment measures, whereas research on distress diagnosis systems and integrated treatment technologies for engineering maintenance applications remains relatively limited. Based on a settlement remediation project for a highway permafrost subgrade in an alpine region of Tibet, this study established a diagnostic and decision-making framework for settlement distress in frozen-soil subgrades and proposed a synergistic treatment technology integrating thermal insulation, drainage improvement, and foundation reinforcement. By developing a distress classification standard and a comprehensive evaluation index system, accurate matching between distress types and treatment schemes was achieved. Combined with insulation layer installation, drainage system optimization, and grouting reinforcement, field implementation and long-term monitoring were conducted to evaluate treatment effectiveness. The results indicate that the maximum settlement of the distressed section decreased from 168 mm to 42 mm, while the annual settlement rate was reduced from 56 mm·a⁻¹ to 12 mm·a⁻¹, corresponding to a settlement control efficiency of 75%. The proposed synergistic treatment technology effectively improved the thermal regime, moisture condition, and structural stability of the subgrade, thereby significantly mitigating the development of settlement distress. The study establishes a comprehensive technical framework for the treatment of settlement distress in frozen-soil subgrades in the alpine regions of Tibet and provides valuable engineering references for highway maintenance and distress remediation in similar cold-region permafrost areas.

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