【作者】 李东阳；

【导师】 刘波；

【作者基本信息】 中国矿业大学（北京） ， 岩土工程， 2011， 博士

【摘要】 本文提出了一种冻土未冻水含量测试新方法。通过分析冻土冻融过程中时间-温度变化曲线,推求了冻融过程中各自的未冻水含量特征曲线。以粘土为例,比较粘土冻融过程中的未冻水含量曲线,观察和分析了未冻水变化的滞后现象。讨论和修改了未冻水含量特征曲线经验拟合公式成立的前提条件,提出了正融过程中未冻水含量特征曲线的经验公式。利用该方法研究了粉土、粘土和粉质粘土在融化过程中的相变特点。探索了冻土正融过程中CT图像灰度值的变化特征,试验结果表明：在冻土温度上升和融化过程中灰度均值随时间呈明显上升趋势；在冻土融化完成时刻,时间-灰度关系图像上有一个明显的折点,是冻土融化完成的标志。结合随机介质理论方法和前苏联一维融土层沉降公式,建立了反映土压力对地表沉降量影响的计算模型。不仅考虑了融化系数的作用,同时也考虑了土体压力的压密作用。结合某地铁联络通道冻结工程,预测分析了正融过程中的地表沉降量。更多还原

【Abstract】 A new test method is proposed to measure the unfrozen water content in frozen soil. Each characteristic graph of unfrozen water is obtained by analyzing temperature-time history during freezing and thawing. The hysteresis of clay was be observed and analyzed by comparing its characteristic graphs of unfrozen water for freezing hand thawing. The assumptions of fitting unfrozen water content curve were discussed and revised, and then a semi-empirical characteristic curve of unfrozen water content during thawing is presented. The characteristic of silt, clay and silty-clay during phase transition are researched by analyzing their test results with this method. The feature of CT images grayscale of frozen soil during thawing is explored. The result discovers that the average grayscale increase obviously as temperature of frozen soil rise and during its thawing. However, after sample thaw complete, the average grayscale is not practically changing even temperature still rising. There is a break point is obviously observed at graph of grayscale-time at the moment of phase-transition finished, which is considered as a symbol of frozen soil melting complete. A mathematical model of ground settlement which include earth pressure and thaw-settlement coefficient is built by combining stochastic media theory with one dimension settlement formulas of thaw soils (former Soviet Union). The model is applied to a lateral artificial freezing engineering of connect aisle for predicting the ground settlement.更多还原