温度梯度下压实黏土的水热迁移规律和渗透特性

开展了室内压实黏土体模型柱试验,研究了温度梯度作用对压实黏土水热迁移和渗透性的响应规律.结果表明:热量在黏土柱下部比黏土柱上部传输快,温度的升高随离热源距离的增加而明显延迟;底部热源促使压实黏土柱产生温度梯度,进而促使水汽在黏土柱内由底向上迁移,造成水分损失较快;随热源的持续作用,黏土柱内温度梯度逐渐下降,水汽迁移速率减小,含水率下降缓慢并趋于稳定.热源持续作用使土柱上表面开裂程度明显大于下底面,用示踪剂来粗略测量裂缝深度是可行的.温度梯度作用不同程度地增大了黏土体的渗透系数,且黏土柱的两端渗透系数增加较快,中间部分增大倍数次之.

Moisture-Heat Migration Laws and Permeability of Compacted Clay Under Temperature Gradient

Through the indoor model experiments， the response laws of the moisture-heat migration and permeability of compacted clay were studied under the temperature gradient. The results demonstrated that: the heat transmitted relatively faster at the bottom of clay column than the upper of clay column; the rise of the temperature underwent an obvious delay with the increase of the distance from the heat source; the heat at the bottom facilitated the occurrence of the temperature gradient inside the compacted clay column， which further prompted the moisture migration from the bottom to the top and caused the quick loss of water; with the continuous heating， the temperature gradient inside the compacted clay column underwent a gradual decline， the rate of moisture migration reduced and the moisture content decreased very slowly and tended to be stable. Under the continuous influence of the heat source， the cracking degree of the upper surface was significantly larger than that of the bottom and it was proved to be feasible to test the cracking depth using a tracer. The temperature gradient raised the permeability coefficient of compacted clay to varying degrees. Moreover， the permeability coefficient at both ends of the clay column rose quickly， followed by that in the middle of the clay column.