Soil parameters form the foundation of hydrogeological research and are crucial for studying engineering construction and maintenance, climate change, and ecological environment effects in cold regions. However, the soil properties in the permafrost region of the Qinghai–Tibet Plateau (QTP) remain unclear. Hence, in this study, soil temperature (Ts), volumetric specific heat capacity (C), thermal conductivity (K), thermal diffusivity (D), soil water content (SWC), electric conductivity (EC), vertical (Kv) and horizontal (Kh) saturated hydraulic conductivity, bulk density (ρb), and soil texture near the Qinghai-Tibet Railway were measured, and their effects on the freeze-thaw process were evaluated. The results revealed a predominantly sandy loam soil texture, with Kh and Kv showing strong spatial variability, while the other parameters presented moderate spatial variability. Thermokarst lake had a limited influence on D, C, K, and ρb but significantly reduced Kh and Kv. Groundwater affected SWC, Ts, and EC. The model results showed that all parameters indicated small sensitivities to the maximum thawing depth (MTD), with MTD positively responding to all parameters except for Kv and porosity (ρp). Except for Kh and Kv, all parameters showed high sensitivities to the time from starting to complete freezing (TSCF). TSCF responded positively to C, ρp, and density (ρd) and negatively to K and Kh. This study expanded the quantification of soil properties in the QTP, which can help improve the accuracy of cryohydrogeologic models, thus guiding the construction and maintenance of infrastructure engineering.

中文翻译：

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研究青藏高原热岩溶湖区土壤性质及其对冻融过程的影响


土壤参数构成了水文地质研究的基础，对于研究寒冷地区的工程建设和维护、气候变化和生态环境影响至关重要。然而，青藏高原 （QTP） 多年冻土区的土壤特性仍不清楚。因此，本研究测量了青藏铁路附近的土壤温度 （Ts）、体积比热容 （C）、热导率 （K）、热扩散率 （D）、土壤含水量 （SWC）、电导率 （EC）、垂直 （Kv） 和水平 （Kh） 饱和水电导率、容重 （ρb） 和土壤质地，并评估了它们对冻融过程的影响。结果显示，土壤质地以沙壤土为主，Kh 和 Kv 表现出较强的空间变异性，而其他参数表现出中等的空间变异性。热喀斯特湖对 D 、 C 、 K 和 ρb 的影响有限，但显著降低了 Kh 和 Kv。地下水影响了 SWC 、 Ts 和 EC。模型结果表明，所有参数都表明对最大解冻深度 （MTD） 的敏感性较小，其中 MTD 对除 Kv 和孔隙率 （ρp） 外的所有参数都呈正响应。除 Kh 和 Kv 外，所有参数均对从开始到完全冻结的时间 （TSCF） 表现出高度敏感性。TSCF 对 C、ρp 和密度 （ρd） 呈正响应，对 K 和 Kh 呈负响应。这项研究扩展了 QTP 中土壤特性的量化，有助于提高低温水文地质模型的准确性，从而指导基础设施工程的建设和维护。