浙江飞云江流域玄武岩残积土滑坡降雨入渗柱状实验研究

浙江飞云江流域广泛发育玄武岩残积土,土体松散,具有膨胀性、可塑性,在人类工程活动及强降雨作用下极易引发滑坡地质灾害。为掌握玄武岩残积土滑坡的成灾机理,选择玄武岩残积土典型滑坡——马济头滑坡,设计了降雨入渗柱状实验,模拟ABA和BAA两种降雨工况条件下土体内地下水入渗规律。结果表明:降雨期,土柱内土体体积含水率逐渐增大至最大值;间歇期,土柱内土体体积含水率减小幅度与土柱深度呈反比。ABA和BAA两种降雨工况的湿润锋入渗曲线形状均为直线型,湿润锋入渗速度不随深度发生变化,且湿润锋入渗速度与降雨强度呈正比。不同降雨工况下,土体体积含水率响应速度差异较明显。

柴河铅锌尾矿中重金属铅、锌、镉的迁移特征

采用柱状淋滤实验模拟降水,研究柴河铅锌尾矿中重金属铅(Pb)、锌(Zn)、镉(Cd)的迁移特征。结果表明:无覆土层的尾矿柱(柱1)与含50cm覆土层的尾矿柱(柱2)淋滤液pH均在30d分别出现最低值5.86和6.67;在180d分别出现最高值7.85和7.89。柱1淋滤液中Pb、Zn、Cd最高质量浓度分别为0.053 0、5.980 0、0.009 4mg/L,均超过《地表水环境质量标准》(GB 3838—2002)的Ⅳ类标准规定的限值。柱2淋滤液中Pb、Cd最高浓度符合GB 3838—2002的Ⅳ类标准,Zn最高浓度超过GB 3838—2002的Ⅳ类标准规定的限值。随着淋滤时间延长,柱2淋滤液中Pb、Zn、Cd浓度均低于柱1,说明表层覆土措施可减少尾矿中重金属淋失。经过柱状淋滤实验,柱2中40cm处Pb、Zn、Cd全量相比原覆土分别增加17.47%、23.37%、26.09%,表明下部尾矿层中的重金属可向上部覆土层迁移。

Experimental Study of Concrete Column Shape Modification Using Fiber Reinforced Polymer Composite Shells and Expansive Cement Concrete

Fiber Reinforced Polymer （FRP） composites are an effective material for strengthening circular concrete columns. The effectiveness of FRP confinement for square and rectangular columns is greatly reduced due to stress concentrations at the sharp comers and loss of the membrane effect at the fiat sides of the cross-section. Shape modification can eliminate the effects of column comers and flat sides, and thereby restore the membrane effect and improve the compressive behavior of FRP-confined square and rectangular concrete columns. Shape modification using chemical post-tensioning, achieved by using expansive cement concrete, is described and several mix designs for obtaining the optimal level of expansion are presented. In addition, parametric studies regarding the optimal geometry of the shape-modified cross-section are presented utilizing the analytical model.