石灰改良膨胀土膨胀性和水稳定性室内试验研究

Laboratory Test the Expansibility and Water Stability of Lime Treated Expansive Soil

针对安徽张庄矿尾矿坝填料膨胀土进行含水率、自由膨胀率δe f、膨胀力Pe和50 kPa压力下的有荷膨胀率δeP50试验,确定膨胀土的膨胀潜势及分布范围,采用掺石灰的方法对土体进行改良并进行击实试验,根据最大干密度和压实度96%制样,研究不同石灰掺量改良土自由膨胀率随养护时间的关系,进行干湿循环试验研究改良土的胀缩变形规律、渗透特性及抗剪强度特性.试验研究结果表明:随着石灰掺量的增加,膨胀土击实后最优含水率逐渐升高、最大干密度逐渐减小;改良土自由膨胀率随着养护时间的增加逐渐减小并于30 d之后趋于稳定;经历6次干湿循环后试样的胀缩变形存在着不可逆性,但掺灰量大于2%的改良土绝对膨胀率小于4%,试样表面无明显裂隙,抗剪强度提高明显,可认为试样膨胀性得到了良好的控制;对于相同石灰掺量的改良土,二次掺灰的改良效果要优于一次掺灰.

In order to determine the swelling potential and distribution range of expansive soil filling of tailingsdam in Zhangzhuang,Anhui,the moisture content,free swelling ratio δe f,expansive force Pe,loaded swelling rateunder 50 k Pa δe P50 are analyzed through laboratory tests. This study deals with the relation between free swellingratio and curing time of different proportion of lime. The cyclic drying and wetting test deals with swelling andshrinkage deformation rule,seepage properties and shear strength of improved soil. The laboratory results showedthat optimum moisture content of expansive soil after hit- solid is increasing with the increasing number ofproportion of lime,while maximum dry density is decreasing. The free swelling ratio of improved soil is decreasingwith the curing time and tends to be stable after 30 days. The nonreversibility of shrinkage deformation rule isdecided after six times＇ cyclic drying and wetting test. The swelling ratio is below 4% while proportion of lime isover 2%. It may be considered that the expansibility and water stability have been well improved through theincreasing of shear strength and less obvious fractures of the patterns＇ surface. Improvement effect of two-step lime-cement mixing is better than one-step for the same proportion of lime.