含砂低液限粉土路用施工技术研究

含砂低液限粉土的路用性能较差,通常不用作高速公路路基填料。云南省新河高速公路沿线广泛分布该类土体,其含水量较高,常规施工难以压实。从技术上讲,对其可用良性土换填、土体改良等方法进行处理,但由于路线附近缺乏良性土料和石料,换填和改良不仅会大幅提高工程造价,同时不利于环境保护。通过改变施工工艺的方法,提高含砂低液限粉土压实度,可以使其满足规范要求。根据气候条件,土料含水量可在每年11月~次年4月间通过翻拌晾晒的方法降低;现场振动压实试验表明,当松铺土层厚度为30 cm、压实遍数不小于5遍时,只要控制好土料含水量的变化范围,压实度是可以确保的;冲击压实试验表明,冲压补强措施对提高压实度是有益的,当压实度不满足要求时可以考虑使用冲压补强。

Construction Technique of Bearing Sand Silt with Low Liquid Limit Used as Highway Subgrade

In most cases,bearing sand silt with liquid limit isn't used as the material to building highway subgrades because its compaction is very difficult.The Xin-He Expressway in Yunnan Province is an important road being constructed.On the basis of modern mature building techniques of highway subgrades,the soil can be replaced by some better soil,or modified by adding some stone or such other materials as cement and lime.But both of the two methods will largely increase the cost to building the road because there isn't better and enough soil or stone near the road line.Another bad aspect of the two methods is they may damage environment.Construction technique,which may improve the degree of compaction of the soil,is therefore investigated in this study.According to the climatic condition at the road,the high water content of the soil can be effectively decreased by rabble under sunlight during the period from November to April next year.The results of vibrating compaction tests indicate that when the thickness of loose soil layer is 30 cm and the repeat number of vibrating compaction isn't less than 5,the degree of compaction of the soil can meet the requirements in the specification for construction of highway subgrades.The results of impacting compaction tests indicate that the impacting compaction is useful to increase the degree of compaction of the soil compacted by the vibrating compaction, so it may be used together with the vibrating compaction to improve the degree of compaction of the soil in actual construction of the highway subgrade.