高液限膨胀性黏土化学改良试验研究

Experimental Study on Chemical Improvement ofExpansive Clay with High Liquid Limit

印尼雅加达至万隆高速铁路路堑挖方以不同膨胀等级的黏土、泥岩为主,黏土的液限和有机质含量较高,国内尚无将该类黏土改良用于高速铁路填筑的先例,为充分利用路堑挖方,降低路基工程造价,对高液限膨胀性黏土进行了化学改良室内试验。试验结果表明:雅万高速铁路沿线黏土平均含水率为42.3%,液限为64.5%,塑性指数为27.7,自由膨胀率为55%,为高液限土,具有弱~强膨胀性;黏土室内改良试件可满足路基填料的压实标准,粉煤灰改良效果不明显,外掺料宜采用石灰、水泥或者石灰+水泥,建议按照掺2%石灰+3%水泥进行现场压实试验;高液限膨胀性黏土掺灰后细颗粒含量依然较多,砂化效果不明显,塑限略有变化,雨季时原土料天然含水率较高,因此改良土施工应选择在旱季进行,并通过晾晒、洒水等控制含水率。

The cutting excavation of Indonesia’s Jakarta-Bandung high speed railway was mainly composed of clays and mudstones with different expansion grades.The liquid limit and organic matter content of clays were relatively high.There was no domestic precedent to improve such clays for high speed railway filling.In order to make full use of cutting excavation and reduce the cost of subgrade engineering,the laboratory test of chemical improvement of high liquid limit expansive clay was carried out.The test results show that the average moisture content of clay along the Jakarta-Bandung high speed railway is 42.3%,the liquid limit is 64.5%,the plasticity index is 27.7,and the free expansion rate is 55%,which is high liquid limit soil with weak and strong expansibility.The clay indoor improvement specimen can meet the compaction standard of subgrade filler,and the improvement effect of fly ash is not obvious.Lime,cement or lime with cement should be used as the external admixture.It is suggested that the field compaction test should be carried out with 2%lime+3%cement.The content of fine particles in high liquid limit expansive clay mixed with ash is still more,the effect of sanding is not obvious,the plastic limit changes slightly,and the natural water content of raw material is higher in rainy season.Therefore,the construction of improved soil should be carried out in dry season,and the water content should be controlled by drying or watering.