以吹填砂为覆盖层的饱和软粘土地基强夯试验研究

Experimental study on dynamic compaction to improve saturated soft c1ay covered with hydraulic fill sand

针对某港区工程陆域不同区域的地质条件和工程荷载,进行了不同工艺的强夯试验,对夯坑周围地表变形、土体水平位移以及孔压的增长和消散进行了观测,并对强夯加固效果进行了试验研究.研究表明,采用强夯法加固以吹填砂为覆盖层的饱和软土地基是可行的,有效加固深度可达到6～7 m,吹填砂层厚度对有效夯击率和碎石土垫层的作用有显著影响.由于吹填砂层和淤泥质粘土层中的粉细砂薄层有利于孔隙水压力的消散,用强夯法处理该类地基时,如果设计加固深度较小时,可以不设置竖向排水体.通过对试验数据的分析研究,获得强夯法加固该类地基土的最佳强夯参数和施工工艺,并且认为选择强夯施工工艺应考虑吹填砂层厚度.

According to geological conditions and engineering loads of different zones of a harbor project, a series of dynamic compaction tests with different techniques were performed. Ground deformation around ramming points , horizontal displacement in soil mass and pore water pressures were monitored; and compaction effectiveness was test. Research results show that it is feasible to treat the saturated soft soil covered with hydraulic fill sand by dynamic consolidation method, of which effective improvement depth is six to seven meters; and the depth of hydraulic fill sand influences remarkably on effective ramming power and function of gravel-soil cushion. Vertical drainage measure may not be taken because of presence of hydraulic fill sand layer and silty sand layer if improved depth to need is shallow. By analyzing the measuring data, the optimal parameters and construction techniques are obtained; and the depth of hydraulic fill sand shall be taken into account when construction techniques is chosen.