预压作用下软土固结蠕变及微观结构试验研究

Test Study on Consolidation-Creep and Microstructure Characteristics of Soft Clayey Soils by Preloading Method

为了揭示预压荷载作用下软土路基工后沉降的机理,开展了室内模拟真空、堆载以及真空—堆载联合预压加固软土的固结蠕变三轴试验及微观结构试验。分析了在三种不同的预压作用下土体固结蠕变性状的不同和微观结构的变化机理。结果表明:在三种不同的预压荷载作用下,固结过程中,是真空—堆载联合预压条件下土体的沉降量最大,其次是堆载预压,最小的是真空预压。蠕变过程的沉降量是堆载预压的最大,其次是联合预压,最小的是真空预压。预压荷载作用下土体的固结和蠕变具有耦合效应;微观结构参数的变化受预压加载方式的影响。微观结构参数的变化率与宏观物性参数的变化率有相似的性质。

In order to explore the mechanism of the settlement after the completion of soft foundation project im- proved by preloading, the triaxial consolidation and creep tests have been carried out which simulate the soft clayey soils under consolidation by vacuum, surcharge, and combined vacuum-surcharge preloading. The microstrueture tests of soft clayey soils before and after triaxial tests have been carried out too. The difference in characteristics of consolidation-creep and mechanism of change of soft soil micro-structure under the loading of three different preload- ing methods were analyzed. The outcome as follows：in the consolidation process, the maximum soil settlement was under the condition of vacuum-surcharge preloading, followed by surcharge preloading, the smallest is vacuum pre- loading. In the creep process, soil settlement was maximally under the condition of surcharge preloading, followed by vacuum-surcharge preloading, the smallest is vacuum preloading. The course of consolidation and the course of creep of samples under the preloading methods have coupling effect ; Changes of microstructure parameters are under the influence of preloading loads. The rate of change of microstructure parameters and the rate of change of macroscopic natural parameters has the similar nature.