降水联合强夯置换在深厚吹填粉煤灰地基加固中的应用

Application of combined dewatering and dynamic compaction replacement in the improvement of deep reclaimed fly ash foundation

近年来,粉煤灰地基的加固处理受到岩土工程界的广泛重视。秦皇岛某粮油项目场地位于废弃的电厂贮灰场区,上部分布有6~9 m厚的吹填粉煤灰层。为消除粉煤灰层的地震液化,提高地基承载力,基于吹填粉煤灰的工程特性和处理后场地的标高要求,确定了井点降水配合强夯置换的地基处理方法。研究表明:对表层承载能力低、地下水位高的软弱粉煤灰场地采用强夯加固时,应先进行降水和低夯击能夯击,待场地浅层的承载能力提高后,再以大夯击能对深部地基土进行加固;加固场地内部应设置轻型井点等可靠的排水通道,以保证超孔隙水压力的有效消散;施工时应以夯坑周围不发生明显隆起为终夯控制标准。本文研究结论对粉煤灰地区的加固具有一定的指导和参考意义。

In recent years,improvement of fly ash foundations has become a focal point in geotechnical engineering.A grain and oil processing project in Qinhuangdao is located in an abandoned power plant ash storage yard,with a 6-9 m thick fly ash layer distributed on the upper part.In order to eliminate the seismic liquefaction of the fly ash layer and improve the bearing capacity of the foundation,a ground improvement method combining wellpoint dewatering with dynamic compaction replacement was used,to meet the requirements of site elevation and properties of the fly ash fill.The results show that dewatering and compaction with low energy should be conducted first when dynamic compaction is used to reinforce weak fly ash sites with low surface bearing capacity and high groundwater level.After the bearing capacity of the shallow layer is improved,the deep soil layer can be improved with large compaction energy.Reliable drainage channels such as light well points should be set up inside the reinforced site to ensure the effective dissipation of excess pore water pressure.During construction,no obvious uplift around the tamping pit should be the final compaction control standard.The findings of this research can provide significant guidance and reference for strengthening measures in fly ash regions.