软土真空预压处理有效性的宏微观分析

地基处理前分析软土宏微观性质对预测真空预压法处理的有效性具有重要意义。通过室内宏微观试验，对珠海金湾地区软土矿物成分、比表面积，以及固结前后的微观结构、孔隙特征等进行分析和研究，得出土体结合水量、强度指标等影响真空预压法处理效果的关键因素。研究结果表明，珠海金湾软土黏土矿物成分含量不高，且黏胶粒占50%，比表面积较黏土矿物小；颗粒呈曲片絮凝状叠聚体，固结变形后出现团聚现象，孔隙压密，无颗粒破碎形状变化；微孔隙尺寸分布主要为400 nm＜r＜2 500 nm，固结后试样的累积进汞量大幅减小，且大孔隙变成小孔隙。说明土体的结合水量不高，含较多的自由水，且内摩擦角变化不大，而黏聚力有较大的增长，真空预压法处理效果明显。

MACRO AND MICRO ANALYSES OF EFFECTIVENESS BY VACUUM PRELOADING TREATMENT OF SOFT SOIL

The macro and micro analyses of soft soil before foundation treatment are important to predict the effectiveness of vacuum preloading treatment. Through the laboratory macro and micro tests，the properties of soft soil from Zhuhai Jinwan area are investigated，including mineral composition，specific surface area，microstructure，pore properties before and after consolidation，etc.. The key factors are concluded which indicate vacuum preloading treatment effect，such as amount of bound water，strength index. Research result shows that clay content of soft soil from Zhuhai Jinwan area is not high，with the clay content about 50%；and specific surface area is small. The soft soil grains are curved flocculation polymer. After consolidation，microscopic structure has noticeably aggregated with compactness and no particle breaking. The micro-pore distribution is mainly between 400 and 2 500 nm. The cumulative intrusions sharply decrease after consolidation，and pores turn smaller. Therefore，the amount of bound water is not high with more free water. The change of internal friction angle is not big，and cohesion has larger growth. It shows good availability of the vacuum preloading method in soft soil from Zhuhai Jinwan area.