高温后上海软黏土的物理性能试验研究

Experimental study on physical properties of Shanghai soft clay under high temperatures

土的温度效应是岩土工程领域的热点问题,但对于100℃以上高温环境下土的物理性能的研究并不多。详细介绍了自行研制的高温加热试验装置,并利用该设备测定了上海软黏土样在105℃,120℃,150℃和200℃等高温加热2.5h和4.0 h后的体积变化、干密度和饱和度的变化,测定了105℃,150℃和200℃下恒温4.0 h土的导热情况。试验结果表明土样的体积和饱和度均随温度增加而减小,土样的干密度随温度的增加而增加,且随加热时间增加变化趋缓;湿土和干土的导热系数均随温度升高而增大,且干土的导热系数小于湿土的导热系数。说明软黏性土在100℃以上高温环境作用下会出现塑性变形和加热硬化现象,高温对土的导热系数影响显著。

The temperature effect of soil is a hot issue in geotechnical engineering. However, the researches on the physical properties of soil in high-temperature environment over 100?C are still insufficient. A kind of self-developed high-temperature heating apparatus is introduced, by which the variations of mass, moisture content, diameter and height of different soft clay samples from Shanghai are measured in the high-temperature environment of 105?C, 120?C, 150?C and 200?C for 2.5 hours or 4.0 hours. The variations of soil conductivity under 105?C, 150?C and 200?C for 4.0 hours are also examined. The experimental results indicate that the volume and saturation of Shanghai soft clay decrease with the increasing temperature while the dry density of soil samples increases, and the trends of variations turn slow. The longer the heating time is, the greater the variation values of volume, saturation and dry density. The high temperature causes the increase of thermal conductivity for wet soil and dry soil and the thermal conductivity of dry soil is less than that of wet soil. Plastic deformation and heat hardening can be found for the soft clay in high-temperature environment, and the high temperature significantly affects the thermal conductivity of soft clay above 100?C.