荷载及细粒土含量对饱和砂卵石冻胀融沉影响研究

Influences of load and fine soil content on frost heave and thawing settlement properties of sandy gravel

以北京典型饱和砂卵石地层为研究对象,研究了不同细粒土含量、荷载条件下饱和砂卵石的冻胀融沉特性。试验结果表明:有载条件下的饱和砂卵石试样冻结初期存在明显的冻缩阶段,冻缩量为试样高度的0.053%;冻胀率及融沉系数均与时间具有明显的指数相关性;相同细粒土含量条件下,饱和砂卵石融沉系数(细粒土含量大于10%)及冻胀率随荷载的增加而减小,荷载对细粒土含量小于10%的饱和砂卵石融沉系数影响微乎其微;相同荷载条件下,饱和砂卵石冻胀率及融沉系数随细粒土含量的增加而增大;荷载对冻胀率影响较大,细粒土含量次之,细粒土含量小于0.82%的无载饱和砂卵石是弱冻胀材料;建立了考虑细粒土含量、荷载影响的饱和砂卵石冻胀率及融沉系数预测模型。

With the typical saturated sandy gravel stratum in Beijing as the research object,the frost heave and thawing characteristics of saturated sandy gravel under different fine soil contents and load conditions are studied.The results show that there is a significant shrinkage phase at the initial stage of freezing of saturated sandy gravel specimens under loading conditions,and the shrinkage is 0.053%of the specimen height.Both the frost heave ratio and the thawing settlement coefficient have an obvious exponential correlation with time.Under the same condition of fine soil content,the thawing settlement coefficient of saturated sandy gravel(the content of fine soil is greater than 10%)and the frost heave ratio decrease with the increase of load,and the load has little effect on the thawing settlement coefficient of saturated sandy gravel with a fine soil content less than 10%.Under the same load condition,the frost heave ratio and thawing settlement coefficient of saturated sandy gravel increase with the increase of fine soil content.Load has the greatest influence on the frost heave rate,followed by the fine soil content.Unloaded saturated sandy gravel with a fine soil content less than 0.82%is a weak frost heave material.A prediction model for the frost heave ratio and thawing settlement coefficient of saturated sandy gravel considering the influence of fine soil content and load is established.