高庙子膨润土和砂混合物膨胀变形特性及其预测.docVIP

  高庙子膨润土和砂混合物膨胀变形特性 及其预测# 孙德安，邵莉娜* 5 10 15 20 25 30 35 40 （上海大学土木工程系，上海 200072） 摘要：内蒙古兴和县高庙子膨润土被确定为我国高放废物地质处置库中首选缓冲回填材料。 本文以高庙子钠基膨润土为试验材料，利用单向固结仪，进行了一维浸水膨胀、浸水湿陷以 及膨胀力试验，分析了该膨润土在不同掺砂率下浸水膨胀和湿陷变形特性等问题。根据蒙脱 石孔隙比的概念，统一整理了饱和时的膨润土及其掺砂混和物的变形特性。试验结果表明， 在低掺砂率下充分吸水膨胀或湿陷或不变形时膨润土与砂混合物的蒙脱石孔隙比与竖向压 力关系在对数坐标是一条直线。由此可预测膨润土及膨润土掺砂混和物在不同的干密度、不 同配合比下吸水至饱和的变形量及膨胀力。用砂孔隙比概念对高掺砂率膨润土混合物的试验 结果进行分析，并可预测高掺砂率混合物在形成砂颗粒骨架时的垂直应力值。 关键词：高庙子膨润土；蒙脱石；孔隙比；吸水膨胀 中图分类号：TU 443 Swelling deformation characteristics of Gaomiaozi bentonite-sand mixture and its prediction SUN Dean, SHAO Lina (Department of Civil Engineering,Shanghai University, ShangHai 200072) Abstract: A bentonite from Gaomiaozi, Xinghe County, Inner Mongolia, has been regarded as the first choice for using as buffer/backfill materials in the high-level waste geological disposal in China. In this paper, one-dimensional swelling deformation tests, collapse tests and swell pressure tests due to wetting were carried out on Gaomiaozi sodium bentonite by using oedometer, for analyzing the swelling and collapse deformation characteristics of mixtures of bentonite and quartz sand in different sand additions. Based on the concept of the montmorillonite void ratio, the deformation characteristics of bentonite-sand mixtures at saturation were consistently identified. Test results indicated that when the content of sand in the mixture is small, the relationship between the montmorillonite void ratio and vertical pressure at saturation is a straight line in the log scales. According to this line, the swelling deformation and pressure can be predicted when the bentonite or its mixtures at different dry densities or mixing ratios absorb water till saturation. Test results of the mixture with high sand fractions were analyzed by using the sand skeleton void ratio, which can predict whether the sand skeleton forms and the vertical pressure when the sand skeleton begins to form. Keywords: Gaomiaozi bentonite; montmorillonite; void ratio; swelling 0 引言 随着我国经