沿海滩涂回填区地基真空预压加固的原观资料分析

结合浙江某码头陆域地基加固工程现场试验研究,基于非理想井固结理论,由实测沉降曲线和孔隙水压力消散曲线推算得到径向固结系数,两者所得结果均大于室内试验的结果.通过对分层沉降和侧向位移监测数据分析可知,真空预压有效加固深度不超过15~20 m.孔隙水压力监测结果表明,真空预压后期停开部分真空泵,即使可以维持膜下真空度的设计要求,但会明显降低了土体的固结速度.十字板剪切实验结果表明,预压后土体的抗剪强度有明显的提高.

Analysis on Field Test Data for Coastal Soft Foundation Improved by Vacuum Preloading Method

Taking the reinforcement project of coal transfer terminal carried out in Zhejiang as example,the radius coefficient of consolidation is evaluated by the curve of settlement and excess pore water pressure based on the non-ideal drain consolidation theory,whose results are larger than that obtained from lab. The monitored settlement at various depths and lateral displacements are analyzed,which indicate that the effective improving depth of vacuum preloading does not exceed 15～20 m.The results of monitored pore water pressure show that the speed of soil consolidation decreases significantly when some vacuum pumps are closed at the later period of vacuum preloading,even though the vacuum degree under membrane can meet the design requirements.The results of field vane shear test indicate that the soil shear strength is improved significantly after preloading.