PAC改进真空预压法加固软土地基试验研究

选取广西吹填造陆场区土样,测试了土样基本物理特性指标,开展了不同聚合氯化铝(以下简称“PAC”)添加量条件下真空预压室内模型试验。通过监测真空预压过程中真空度传递和超静孔隙水压力消散的情况,得到了排水量、超静孔隙水压力消散、真空度随时间变化规律以及不同添加量下的排水稳定时间;通过十字板剪切强度测试得到了十字板剪切强度随深度增加逐渐减小的规律;分析了聚合氯化铝改进真空预压法的加固性能。研究结果表明:聚合氯化铝的存在可以提高真空预压的加固效率,缩短加固周期10%~35%;超静孔隙水压力消散值相比较未掺加组提高了20%~30%;真空压力损失比未掺加组试样最高可降低11%,真空加载稳定所需耗时降低了约20%~50%,有效降低真空压力达到稳定的时间,实现了快速稳定真空加载的目的;加固后十字板强度提高了20%~30%;聚合氯化铝添加量存在较优掺加配比,当掺加比为0.3‰时具有较好的应用价值。

Effect of Poly Aluminum Chlorideon on the Treatment of Dredger Fill with Vacuum Preloading Method

The basic physical properties of the soil samples in the land reclamation area of Guangxi were tested, and the indoor model test of vacuum preloading was carried out under the condition of different amount of polyaluminium chloride addition. By monitoring the vacuum degree transmission and excess pore pressure dissipation during the vacuum preloading process, the law of drainage, excess pore water pressure dissipation, vacuum degree changing with time were obtained, and the time duration for reaching drainage stability was investigated. The results show that the vane shear strength of soil after cementation decreases with the increase of the depth; the presence of PAC can improve the efficiency of vacuum preloading, shorten the period of reinforcement by 10% ~ 35%; the dissipation value of excess pore water pressure is increased by 20% ~ 30% compared with the natural samples; the maximum loss of vacuum pressure can be reduced by 11% compared with the natural samples, and the time required for vacuum loading stability can be reduced by about 20% ~ 50% .After vacuum cementation, the vane shear strength is increased by 20% ~ 30%. There is an optimal addition percentage of PAC and in this research, and the ratio of 0.3 ‰ PAC is proposed for possible application.