疏松粉细砂无填料振冲加固机理研究

无填料振冲法加固粉细砂地基较为少见。结合上海市某重点工程,通过现场试验研究粉细砂的无填料振冲加固特性,包括对初始地下水位影响特点、孔隙水压力消散规律、静力触探和标准贯入效果进行深入分析。结果表明:初始地下水位过低对粉细砂加固不利,振冲过程中产生的孔隙水压力与振点和振冲次数关系密切,振冲加固后地基承载力明显提高。总结试验结果,提出了基于疏松粉细砂的工程特性和合理施工工艺和技术参数,研究结果定性验证了无填料振冲法加固粉细砂的适用性。

STUDY ON THE VIBROFLOTATION MECHANISM OF LOOSE SILTY FINE SANDS WITHOUT ADDITIONAL BACKFILL

The application of vibroflotation without additional backfill treatment in silty fine sands is not so common.Combined with one key project in Shanghai,the engineering properties of saturated loose silty fine sands were investigated through in-situ vibroflotation test.The effect of initial underground water level,dissipation regularity of pore water pressure,effects of cone penetration test(CPT) and standard penetration test(SPT) were explored.Research shows that the treatment effect is not so good if the underground water level is too low,and the pore water pressure generated during vibroflotation is related closely with the vibroflotation points and frequency,and foundation capability is greatly improved after treatment.Summarizing the rest results,some rational construction techniques and parameters were suggested.Research testified the applicability of vibroflotation without additional backfill treatment in saturated silty fine sands.