冻融循环次数对黄土路用性能影响规律的试验

Test research on change law of highway performance at loess are influenced by number of freeze-thaw cycles

以黄延(黄陵—延安)高速公路沿线黄土为研究对象,在不补水条件下对天然土样和饱和土样进行多次冻融循环,每经过2次冻融循环后测定土样的界限含水率、剪切强度及压缩模量等路用性能参数。测试结果表明:经过多次冻融循环后,黄土的液限降低,塑限变化较小,从而导致塑性指数降低;随着冻融循环次数的增加,2种土样的粘聚力呈减小趋势,内摩擦角则相反,其中饱和土样的粘聚力降低幅度比较明显,内摩擦角变化不大;土的压缩性随着冻融循环次数的增加而逐渐增强,饱和土样压缩模量降低幅度明显高于天然土样,即冻融循环对饱和土样的压缩性影响较大。

Take the loess along Huang-Yan highway as the object of research, freeze-thaw cycles were carried out on natural soil samples and saturated soil samples without water supplied, and parameters of highway performance, such as water ratio limit, shearing strength, compression modulus and so on, were obtained after every two times of freeze-thaw cycle. The results of tests show that liquid limit of loess decreases, plastic limit remains unchanged, and plastic index de- creases. With more times of freeze-thaw cycle, cohesive forces of two soil samples tend to de- crease but angles of internal friction tend to increase. Reduction of saturated soil＇s cohesive force is larger and growth of internal friction angle is smaller. Compressibility of loess more with in-creasing times of freeze-thaw cycle, compression modulus of saturated soil changes more obvious-ly than that of natural soil, that is to say compressibility of saturated soil is more influenced by freeze-thaw cycle. 2 tabs, 12 figs, 10 refs.