压实度及水分对青藏高原季冻区砂砾土冻胀特性的影响

Influence of compaction degree and moisture on frost heaving properties of gravel soil in seasonally frozen region of Qinghai-Tibetan Plateau

针对青藏高原季冻区某机场道基主要材料砂砾土,通过实验系统地研究了压实度、初始含水率及补水状况对砂砾土冻胀特性的影响规律。结果表明,在封闭条件下,若初始含水率不变,则砂砾土冻胀率随压实度的增加呈先增大后减小的趋势,在压实度为95%左右时达到最大值,若压实度不变,则冻胀率随初始含水率的增加呈线性增大;压实度和初始含水率均与冻胀率之间存在高度相关的函数关系,这些关系式在某些情况下可用于相关指标的相互预测。在开放条件下,砂砾土的冻胀率较封闭条件下显著增大,通常达3～4倍以上。为有效防治砂砾土冻胀,应严格控制压实度和初始含水率,同时采用降低地下水位、设置隔水垫层等措施阻止外界水源补充。

In order to see the influence of the compaction degree and the moisture on the frost heaving properties of the gravel soil in the seasonally frozen region of Qinghai-Tibetan Plateau, and provide a foundation for the prevention and the control of the soil frost heaving, a series of frost-heaving ratio indoor tests with improved test devices are conducted to study the influence of the compaction degree, the initial moisture content and the water replenishing on the frost-heaving ratio . It is shown that, the frost-heaving ratio of the gravel soil decreases after the first increase with the increase of the compaction degree, with its maximum at the compaction degree of 95% under the closed condition and with the same initial moisture content, and it increases linearly with the increase of the initial moisture content under the closed condition and with the same compaction degree. There are highly related functional relationship between the compaction degree, the initial moisture content and the frost-heaving ratio, which can be used to forecast related indicators in some cases. The frost-heaving ratio increases over several times under the open condition than under the closed condition. It is necessary to reduce the underground water level, to set the water-resisting layer, and to strictly control the compaction degree and the initial moisture content for the effective prevention and control of the soil frost.