摘要
青藏公路沿线冻土对工程建设和后期运营维护具有重要影响,历来是研究重点。基于青藏公路沿线167个钻孔地质调查数据,对土样冻胀力与天然密度和含水量的关系进行分析,依据冻胀力进行评价。结果表明:沿线天然密度集中于1.9~2.2 g?cm?3之间;冻胀力受天然密度的影响可分为三个阶段,I:土体天然密度在1.8~1.9 g?cm?3时,冻胀力随着天然密度的增加而急剧减小;II:在1.9~2.2 g?cm?3时,冻胀力呈现缓慢下降的趋势;III:在2.2~2.6 g?cm?3时,此时由于土体密实度较大,颗粒间只存下少量微孔隙和裂隙,冻胀力因而基本保持不变;同时冻胀力随天然含水量的增加而增加,其增加趋势亦可以分为三个阶段,I:天然含水量为10%~25%时,冻胀力随含水量的增大而快速增大;II:25%~40%时,冻胀力随含水量的增加而缓慢增加;当含水量达到40%后,进入阶段III,此时冰分子成为土体的主要部分,冻胀力趋于冰的冻胀力。西大滩断线谷地–阿青岗尔陇巴河谷区段,地下水水位较深,浅层为少冰冻土,含水量较低,冻胀力较小;在楚玛尔河高平原段,地表水系发育,浅层含水量较大,使其冻胀力达到37 kPa,为沿线最大值。
Permafrost along the Qinghai-Tibet Highway has an important impact on engineering construction and late operation and maintenance. Based on the geological survey data of 167 boreholes along the Qinghai-Tibet Highway, the relationship between frost heaving force and natural density and water content of soil samples was analyzed and evaluated according to frost heaving force. The results show that the natural density along the line is concentrated from 1.9 g?cm?3 to 2.2 g?cm?3. And the frost heaving force decreases with the increase of the natural density. Frost heaving force is affected by natural density in three stages. First of all, the natural density of soil ranges from 1.8 g?cm?3 to 1.9 g?cm?3. The frost heaving force decreases sharply with the increase of natural density. Second, the natural density ranges between 1.9 g?cm?3 and 2.2 g?cm?3. The large pores in particles decrease and the frost heaving force shows a slow decline trend. Third, the natural density ranges from 2.2 to 2.6 g?cm?3. Due to the relatively high soil compactness, there are only a few micro-pores and cracks in particles. Frost heaving force thus remains essentially constant. At the same time, the frost heaving force increases with the increase of natural water content, which can be divided into three stages. First, the natural water content ranges from 10% to 25%, the frost heaving force increases rapidly with the increase of water content. Second, the natural water content ranges from 25% to 40%. Frost heaving force increases slowly with the increase of water content. When the water content reaches 40%, it enters the third stage, when the ice molecules become the main part of the soil. Frost heaving tends to ice. In the section of Xidatan broken line valley-Erlongba valley, the groundwater level is deep, the shallow layer is little frozen soil, the water content is low, and the frost heaving force is small. In the high plain section of Chumar river, the surface water system is developed and the water content in the shallow layer is relatively large, which makes the frost heaving force reach 37 kPa. That is the maximum along the line.
出处
《土木工程》
2020年第1期27-34,共8页
Hans Journal of Civil Engineering
基金
国家自然科学基金:51879207
西京学院高层次人才专项基金:XJ17B05。
