【摘要】 目的:压缩性和渗透性是垃圾填埋场竖向隔离墙材料的2个重要指标。本文旨在探讨不同凹凸棒土添加量对砂-凹凸棒土隔离墙材料压缩性和渗透性的影响,并在Kozeny-Carman方程的框架下建立经验公式来预测砂-凹凸棒土隔离墙材料的渗透系数。创新点:1.系统全面地研究了不同凹凸棒土添加量对砂-凹凸棒土隔离墙材料压缩性和渗透性的影响;2.建立经验公式,预测砂-凹凸棒土隔离墙材料的渗透系数。方法:1.通过固结试验和刚性壁渗透试验,得出不同凹凸棒土添加量对砂-凹凸棒土隔离墙材料压缩性和渗透性的影响(图3和4,表1);2.通过公式推导,建立经验公式来预测砂-凹凸棒土隔离墙材料的渗透系数(公式(3)和(4))。结论:1.压缩指数(Cc)和回弹指数(Cs)均随回填料中凹凸棒土含量(Ap)的增加而增大,且Cc和Cs与Ap均有很好的线性关系:Cc=0.0062Ap+0.0161(r2=0.9914),Cs=0.0009Ap-0.0058(r2=0.9888)。2.用Casagrande和Taylor方法计算的固结系数(Cv)值均随回填料中凹凸棒土含量的增加而降低。3.利用太沙基固结理论计算的回填料渗透系数(ktheory)随回填料中凹凸棒土含量的增加而降低;在有效固结压力σ′<100 k Pa的情况下,只有凹凸棒土含量Ap≥30%,ktheory才会低于10-9 m/s;用刚性壁渗透试验测得的渗透系数kf与ktheory有相同的变化特征。4.基于试验数据提出了2种预测砂-凹凸棒土回填料渗透系数的方法,其中方法 2更好;由于这些方法都是经验公式,所以它们能否应用于原位场地或其它类型回填料仍需进一步的研究。更多还原

【Abstract】 Soil-bentonite cut-off walls have been used widely to control pollution in landfills but their antifouling property（their ability to prevent contaminants in landfills from polluting the surrounding environment） decreases significantly over time due to a variety of factors（e.g. contaminant concentrations）. In recent years, attapulgite has been considered as a backfill material for cut-off walls, but relevant studies are lacking. In this study, the compressibility and hydraulic conductivity of sand-attapulgite backfills were investigated using consolidation and hydraulic conductivity tests. In these tests, attapulgite comprised 10%, 20%,30%, 40%, 60%, 80%, or 100%（dry weight） of the backfills. The results showed that（1） the compression（C_c） and swell（C_s）indexes of the backfills increased linearly with increasing attapulgite content（A_p）;（2） both the consolidation coefficient（C_v）calculated by the Casagrande and Taylor methods and the hydraulic conductivity(k_theory) calculated according to Terzaghi consolidation theory decreased with increasing attapulgite content. In the case of an effective consolidation stress σ′<100 kPa, k_theory<10-9 m/s when A_p≥30%, which was supported by the hydraulic conductivity tests. Two methods were developed based on laboratory data, for predicting the hydraulic conductivity of sand-attapulgite backfills. We conclude that the use of sand-attapulgite backfills applied to cut-off walls as substitutes for soil-bentonite backfills is technically feasible.更多还原