回收石膏粉末改良路基软黏土试验研究

Experimental Study on Improvement of Subgrade Soft Clay by Recycled Gypsum Powder

在南方某湖区高速公路现场采取了软黏土,制备了不同石膏粉末掺量的改良土试样,开展了无侧限抗压强度试验、劈裂试验、CBR试验等,探讨了强度、CBR值、膨胀性等随改良剂掺量的变化规律,获取了改良土用于下路堤填筑的合理改良配比。研究结果表明,随着回收石膏粉末掺量增加,土的干密度增加,含水率减小,可以缩短压实填筑前的翻晒时间;此外抗压强度、劈裂强度和CBR都有所提高,其中CBR的提高效果最为明显。当2种软黏土中石膏粉末掺量达到81 kg/m^(3)和109 kg/m^(3)时,改良土的CBR达到下路提填筑标准。采用石膏粉末改良软黏土的同时,配入水泥,所得的改良土在浸水饱和条件下膨胀量较小,表明其具有一定的水稳定性,可满足下路堤填筑要求。

This studycollected soft clay soil specimens at a certain expressway construction site in lake district of south china.Some improved soil specimens with different dosage of gypsum powder were prepared,and a series of compressive strength tests,splitting tests and CBR tests were carried out.The variation rule of intensity,CBR and swelling feature with modifier content was discussed.The reasonable ratio for modifier used for improving soil clay to meet the standard of lower embankment filling was acquired.The research results show that with the increase of gypsum powder content,the dry density of soil increases,the moisture content is reduced which means the ted time before compaction filling can be shorten.In addition,the unconfined compressive strength,splitting strength and CBR are also enhanced,and the enhancement of CBR is most obvious.In order to achieve the lower embankment CBR requirement,the required modifier content for two kinds of soft clay should be up to 81 kg/m^(3) and 109 kg/m^(3).When gypsum powder is used to improve soft clay and cement is added,the improved soil has a small expansion tendency even under saturated condition,therefore it has an ideal water stability and can meet the requirement of lower embankment construction.