季节冻土区纤维改良路基土热物理学特性研究

Study on Thermophysical Properties of Fiber-reinforced Subgrade Soil in Seasonal Frozen Soil Region

为研究冻融循环下纤维改良粉砂土路基的含水率、干密度、纤维掺量对土体热物理学特性的影响规律,通过开展室内导热系数测试试验,测得不同含水率、干密度、纤维掺量改良粉砂土的导热系数,分析不同因素对改良粉砂土导热系数的影响。结果表明,在干密度、纤维掺量以及冻融次数相同的情况下,改良路基土的导热系数随含水率的增大呈非线性增长,且当含水率超过12%时,增长速率减小,试验范围内导热系数为0.39~1.32 W/(m·K);在含水率、纤维掺量以及冻融次数相同的情况下,改良路基土的导热系数随干密度的增大呈指数增长,且当干密度超过1.9 g/cm^(3)时,增长速率减小,试验范围内导热系数为0.45~1.87 W/(m·K);在含水率、干密度以及冻融次数相同的情况下,改良路基土的导热系数随纤维掺量的增大线性减小,试验范围内导热系数为0.59~1.3 W/(m·K);在含水率、干密度以及纤维掺量相同的情况下,改良路基土的导热系数随冻融循环次数的增大线性减小,试验范围内导热系数在0.48~1.01 W/(m·K)。研究成果可为西部粉砂土分布地区工程建设提供参考。

In order to study the effects of moisture content,dry density and fiber content of fiber-modified subgrade soil on the thermophysical properties of soil under freeze-thaw cycles,the indoor thermal conductivity tests are carried out to measure the thermal conductivity of silty sand with different moisture content,dry density and fiber content,and the effects of different factors on thermal conductivity of subgrade soil are analyzed.The results show that,(a)under the same conditions of dry density,fiber content and freezing-thawing times,the thermal conductivity of improved subgrade soil increases nonlinearly with the increase of moisture content and the growth rate decreases when the moisture content exceeds 12%,and the thermal conductivity in these tests is 0.39-1.32 W/(m·K);(b)under the same moisture content,fiber content and freezing-thawing times,the thermal conductivity of improved subgrade soil increases exponentially with the increase of dry density,and when the dry density exceeds 1.9 g/cm^(-3),the growth rate decreases,and the thermal conductivity in these tests is 0.45-1.87 W/(m·K);(c)the thermal conductivity of improved subgrade soil decreases linearly with the increase of fiber content,and the thermal conductivity in these tests is 0.59-1.3 W/(m·K);and(e)in the same moisture content,dry density and fiber content,the thermal conductivity of improved subgrade soil decreases linearly with the increase of freezing-thawing cycles,and the thermal conductivity in these tests is 0.48-1.01 W/(m•K).The research results can provide reference for engineering construction in the west of China where the silty sand is distributed.