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Study on the Prediction Model of Unfrozen Water Content and the Variation of Parameters in Silty Clay |
DENG Shi-lei1, WAN Xu-sheng1, LU Jian-guo1, LI Shuang-yang2, YAN Zhong-rui1
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1. School of Civil Engineering and Geomatics, Southwest Petroleum University, Chengdu Sichuan, 610513, China; 2. State Key Laboratory of Frozen Soil Engineering, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou Gansu, 730000, China |
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Abstract The engineering characteristics of frozen soil are closely related to the unfrozen water content, so the determination of unfrozen water content is of great theoretical significance for engineering hydrothermal simulation in cold regions. In order to study the change law of liquid water content during cooling process, the characteristics of three classical unfrozen water content prediction models were compared and analyzed, and the applicable temperature range and parameters variation of the models were discussed. Firstly, based on the existing prediction model of unfrozen water content, 29 groups of experimental data of silty clay were selected to analyze the prediction effect of unfrozen water content, the values of model parameters were determined, and the influence of each parameter on the curve shape of model was studied. Secondly, the Root Mean Squared Error (RMSE) and Average Deviation (AD) of the model were calculated, and the calculation accuracy of the model was discussed. Finally, the upper and lower boundaries of the data scatter diagram were drawn to obtain the reference range of the model parameters, and the relationship between the model parameters and the initial water content was analyzed. The results show that Anderson and Tice's (1972) model has the highest calculation accuracy for specific soil samples; Dall' Amico et al.'s (2011) model has better prediction effect, and the integrity of the model is better; Michalowski's (1993) model has larger prediction error. Anderson and Tice's (1972) model overestimates unfrozen water content in soil, while the latter two underestimate unfrozen water content. With the variation of initial water content, the parameters of Anderson and Tice's (1972) model show a wide range of values, and the prediction has uncertainty; Michalowski's (1993) model takes the second place; Dall' Amico et al.'s (2011) model has the smallest range of variation. The values of parameters a and μ increase with the increase of initial water content, while parameters b, α, n and m have no clear law with the increase of initial water content.
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Received: 26 November 2020
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Fund:Supported by the National Natural Science Foundation of China (Nos.42071087, 41601068); Sichuan Science and Technology Program (No.2021YFQ0021); Open Foundation of State Key Laboratory of Permafrost Engineering (No.SKLFSE202007); Key R & D and Transformation Projects in Tibet Autonomous Region (No.XZ201801-GB-07) |
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