开展了室内模拟真空、堆载以及真空—堆载联合预压作用下软土的三轴固结试验；拍摄了试样在三轴试验前后的SEM电镜扫描照片；从宏观工程性质和微观结构变化及二者结合的角度研究了在三种预压方式下土体加固效果的不同和机理的差异.结果表明:土体的微观结构在预压荷载加固后发生了显著的变化,微观结构参数的变化与各自加载的方式相符,并与宏观物性参数的变化密切相关；宏观物性指标和微观结构参数的变化都表明,联合预压的效果最好,真空预压次之,最小的是堆载预压.试验说明土体的宏观工程性状在本质上决定于微观结构.%The triaxial compress tests of soft soils under consolidation by three preloading methods of vacuum, surcharge, combined vacuum-surcharge are performed, and the SEM photos are taken before and after the tests from up, middle and bottom of soil samples which describe the microstructural changes in the different preloading methods: Reinforcement effects and mechanisms of three preloading methods are analyzed with the micromechanics, macroscopic engineering properties of soils, and combination of both. The relationship between changes of microstructural index and engineering characteristic of soft soil are studied. The results show that: The microstructure of soil has remarkable change after the precompression load reinforcement. The changes in the microstructure parameters consistent with their way of preloading, and are relative closely to the changes of macroscopic parameters of the soils. Index changes of both macroscopic properties and microstructure indicate that combined effect of preloading is the best, followed by vacuum preloading, the smallest is surcharge preloading. The experiment result which means that the macro-engineering behavior of soil is essentially determined by the microstructure.
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