不同温度下红黏土胀缩性试验研究

Experimental Study on Swelling and Shrinkage Properties of Red Clay at Different Temperatures

为了探究温度对红黏土胀缩性的影响,通过不同温度下红黏土的胀缩性试验(膨胀变形和收缩变形试验),以初始含水率和干密度为对比变量,分析红黏土胀缩性;并通过红黏土的收缩变形试验分析温度对红黏土体缩率、最终线缩率和收缩系数的影响规律。试验结果表明:膨胀率随着初始含水率的变化而变化,干密度最大的试样的膨胀率增幅最明显,干密度最小的试样的膨胀率却随着初始含水率的增加而减小;随着温度的升高,膨胀率总体呈增大趋势,膨胀率在 80℃之前缓慢增长,超过 80℃时增长较快;随着温度的升高,线缩率、体缩率、收缩系数总体呈现递减的趋势;不同温度下红黏土随着含水率的降低,收缩曲线大致可以分为斜直线阶段、外凸阶段和直线稳定阶段共 3个阶段,各阶段的收缩速度和收缩变化幅度不同。研究成果可为研究红黏土胀缩性的岩土工程技术人员提供参考。

In this paper, the swelling and shrinkage properties of red clay under different temperatures were studied via swelling deformation and shrinkage deformation test with initial moisture content and initial dry density as contrast variables. The influence of temperature on volumetric shrinkage rate, final linear shrinkage rate, and shrinkage coefficient was analyzed. The experimental results revealed that expansion rate increased correspondingly with the rising of initial moisture content;the expansion rate of sample with the highest dry density increased most obviously, while the expansion rate of sample with the lowest dry density decreased with the rising of moisture content.With the climbing of temperature, shrinkage rate presented an overall increasing trend, and in particular, expansion rate surged when temperature exceeded 80 ℃;but volumetric shrinkage rate, linear shrinkage rate and shrinkage coefficient displayed a holistic declining trend. As moisture content declined, the shrinkage curve of red clay can be divided into three stages at different temperatures: oblique straight line, convex, and straight lines, each with different shrinkage velocities and amplitudes.