应用碱性水泥外掺剂固化天津海积软土的试验研究  

TEST AND STUDY ON THE SOLIDIFYING TIANJIN MARINE SOFT SOIL WITH ALKALESCENT CEMENT ADDITIVE

作　　者：王宝勋[1,2] 李夕兵[1] 杜东菊[3] 杨爱武[3] 

机构地区：[1]中南大学,长沙410083 [2]天津华北地质勘查局,天津300181 [3]天津城市建设学院,天津300384

出　　处：《工程地质学报》2009年第3期426-432,共7页Journal of Engineering Geology

基　　金：天津市社会发展科技项目(No.04311381);天津市科技攻关项目(编号:06yfszsf04000)

摘　　要：天津海积软土具有高含水量、低强度、高压缩性、低pH值等特征,不能直接满足工程建设需要,必须进行人工处理。在水泥土搅拌法中使用适量碱性外掺剂NaOH或Na2CO3,可以提高桩身水泥土强度和复合地基承载力,同时能节省大量水泥,降低工程费用。现场试验中将海积软土与分别掺入0.5%NaOH和0.5%Na2CO3的10%水泥就地搅拌,形成两种新型水泥土,在与原状土及20%纯水泥土进行比较后,发现碱性外掺剂可以促使生成大量针状、棒状或纤维状水化硅酸钙晶体,抑制了能产生膨胀作用的钙矾石的生成,同时,有Ca(OH)2晶体析出,它们共同构成土颗粒间和土颗粒表面的充填物和包裹物,使水泥固化土的孔隙明显减小,密度和强度得到极大提高。检测结果显示水泥土强度提高了20%以上,复合地基承载力不小于120kPa。The marine soft soil in Tianjin coastal region has high water content, low strength, high compressibility and low pH. It cant meet the needs of engineering construction and has to be improved. One of the soil improvement methods is to mix feasible alkalic additive sodium hydroxide or sodium carbonate into the whisking cement soil. This method can improve the strength of pile cement soil and the bearing capacity of composite foundation, and save a great deal cement. In this paper, the marine soft soil is mixed with 10% cement added with 0.5% NaOH and 0.5% Na2CO3 separately, which form two types of new cement -soils. Comparing with the undisturbed soil and the 20% cement - soil results in that the alkalescence additive can contribute to generate a large number of needle -like, rod -like or fibriform hydrate calcium silicate crystals. The hydrate calcium silicate crystals can inhibit the generation of calcic alum crystal which would bring expansive action. At the mean time, it can separate out hydrate calcium. The hydrate calcium silicate crystals and hydrate calcium constitute the filling and inclusions together among soil particles and on the surface of soil particles, which cut down the interstices of cement soil obvi-ously. Therefore, the soil mass can be reinforced and the intensity can be improved. Test resuhs show that the soil - cement strength increases more than 20%. The composite foundation bearing capacity is not less than 120kPa.

关 键 词：外掺剂 海积软土 水泥土 微观结构 

分 类 号：P642[天文地球—工程地质学]