考虑干湿循环路径的石灰改性红黏土路用性能试验研究

Experimental study of pavement performances of lime-treated laterite soil considering drying-wetting cycle paths

红黏土是一种对环境湿、热变化敏感的高塑性黏土,用作路基填料时,为改善其路用性能,并延长路基使用寿命,工程中通常掺入一定剂量的石灰对其进行改性。在地下水、降雨入渗和蒸发等自然营力作用下,运营期间路基土的含水率反复变动会对其工程特性产生一定影响。采用两种与实际工况接近的典型干湿路径,开展红黏土及其石灰改性土的强度和变形特性对比试验研究。试验结果表明:均匀干湿循环作用下,石灰改性土的黏聚力减小,内摩擦角小幅度增大,抗剪强度略高于红黏土,改性效果不明显;定向干湿循环作用下,石灰改性土的收缩裂缝较少,强度和变形参数均显著提高,路用性能得到明显改善。

Laterite soil is one kind of high plastic clay being very sensitive to environmental heat and moisture variation,and mixing optimal ratio of lime into laterite soil is made when construction to improve pavement performance and prolong the life span.Engineering properties of subgrade are obviously affected by soil moisture state and its drying-wetting history during excavation and exertion of the expressway.Experimental investigations on strength and deformation properties of lime-treated laterite soil and laterite soil are carried out,considering two drying-wetting paths which are exactly accordant with practices.The results indicate that： with uniformity drying-wetting cycles,lime-treated soil,internal friction angle increase a little and cohesive strength decrease with shearing strength reducing and pavement performance has not improved greatly.With directional drying-wetting cycles,lime-treated soil have less drying-shrinking cracks with unconfined compression strength and deformation resistance decreasing a little and the long-term strength and deformation performance enhanced significantly.