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真空—堆载联合预压法是一种较好的软基处理方法。但是与工程实践相比较,理论研究相对滞后,为弄清机理,提高设计和施工水平,有必要作进一步深入的研究。对九江大桥至江门市公路软基进行现场试验研究,分析结果表明:一般在地基相同的深度处:塑排真空度>淤泥真空度。加固区内地基中的孔隙水压力的最大消散值可分为两个组成部分:一为真空度的直接传递导致的孔压下降值;二为抽真空引起水位线下降进而引起的孔压消散值。淤泥地基中孔隙水压力消散主要是由于地下水位线的下降引起的;而塑排中的孔压消散大部分由真空度直接引起。在路基填筑期间,淤泥地基与竖向排水体之间的孔压差增大,加速土体固结。地表的水平位移影响范围可达24m,约为1倍排水板深度的距离。通过十字板剪切试验与静力触探试验,加固后土体的抗剪强度一般可提高1.5~6倍,说明真空联合堆载预压加固软土地基的效果显著。
Vacuum - stowed combined preloading method is a better method of soft foundation treatment. However, compared with engineering practice, theoretical research lags behind. In order to clarify the mechanism and improve the design and construction level, it is necessary to do further research. The field test on the soft ground of Jiujiang Bridge to Jiangmen Highway was carried out. The analysis results show that the vacuum at the same depth is the same as the vacuum at the bottom of the foundation: the vacuum degree of the vat> the degree of vacuum of the sludge. The maximum dissipation of pore water pressure in the foundation in the reinforcement zone can be divided into two components: one is the pore pressure drop caused by the direct transfer of vacuum; the other is the pore pressure dissipation caused by the water level drop caused by vacuum pumping . The dissipation of pore water pressure in the silt foundation is mainly caused by the drop of groundwater level line, while the dissipation of pore pressure in the planing is mostly caused by the degree of vacuum directly. During subgrade filling, the pore pressure difference between silt foundation and vertical drainage body will increase, which will accelerate soil consolidation. Surface horizontal displacement of up to 24m, about 1 times the depth of the drainage board distance. The shear strength of soils can generally be increased by 1.5 ~ 6 times by means of the cross-shear test and the static penetration test, which shows that the effect of vacuum combined with preloading on consolidation of soft soil foundation is remarkable.