Pavement deformation risk assessment in permafrost regions based on cone penetration test

To investigate the load-bearing characteristics of shallow permafrost and the patterns of road surface deformation in the permafrost regions of the Qinghai-Tibet Plateau, representative areas were selected for onsite road surface deformation surveys and in situ cone penetration tests. Greater penetration resistance ratio or cone tip resistance correlates with reduced penetration depth during the Cone Penetration Test (CPT), indicating stronger load-bearing capacity in the respective area and consequently lesser road surface settlement. Smaller values of penetration resistance ratio or cone tip resistance, coupled with greater thickness in the region, result in more severe road surface deformation. Based on the penetration resistance ratio and cone tip resistance of the permafrost strata, the concept of the envelope area ratio is proposed to evaluate the load-bearing capacity of shallow permafrost. Under identical standard conditions, a larger envelope area ratio of either the P_s-d or q_c-d curves indicates stronger load-bearing capacity of the permafrost strata and lower surface settlement risk. Empirical formulas correlating the envelope area ratio of the P_s-d and q_c-d curves with the maximum value of road surface settlement were established, with determination coefficients exceeding 0.9.