摘要
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。
Bumping Vacuum combined with surcharge preloading is a good method to reinforce soft foundation. But the mechanism of the vacuum combined with surcharge preloading is not clear, it is necessary to study the method. The field test of soft ground of the highway from Jiujiang Bridge to JiangMeng city was performed and the observation results of test site were analyzed. The results show that the vacuum degree in the PVDs is higher than the vacuum degree in the silt at the same depth in the ground. The value of pore water pressure dissipation can be divided into two phases. The first is produced by vacuum degree drop and the second is produced by groundwater table lowering. The pore water pressure dissipation in the silt is produced mainly by lowering of the groundwater table and the pore water pressure dissipation in the PVDs is produced mainly by the vacuum degree drop. The dissipation value of pore water pressure does not change along the depth. The pore water pressure difference between silt and PVDs increases and the soil consolidation velocity is accelerated during the embankment construction. The increase of vacuum energy can not accelerate the surface settlement when the flow is small. The influenced scope of soil horizontal displacement is 24m away far from the improvement area border, about the same depth as PVDs. The shear strength increases by 1.5 - 6 times after improvement with vane shear test and the resistance increases largely with CPT. The soft foundation treated by the vacuum combined with surcharge preloading is very effective.
出处
《建筑科学》
北大核心
2010年第1期50-55,共6页
Building Science
基金
河北省交通厅基金项目资助(项目编号Y-060236)
关键词
真空-堆载联合预压法
现场试验
真空度
孔隙水压力
沉降
vacuum combined with surcharge preloading
field test
vacuum degree
pore water pressure
settlement
