强夯置换的ALE法仿真与夯击参数研究

Simulation of dynamic compaction replacement using ALE method andtamping parameters

为揭示强夯置换动态变形特征与地基加固变化规律,将基于有限差分原理的ALE法引入强夯置换仿真分析,建立三维ALE法强夯置换动力分析模型,模拟单次夯击与连续强夯置换地基加固过程,分析不同夯击参数对高能级强夯置换加固效果影响并应用于工程实例。结果表明:ALE法可描述碎石填料夯击流动变形,实现连续强夯置换仿真;回填碎石对夯击能吸收作用可削弱夯击地基加固效果,故采取“少填多夯”方式较合理;针对8000 kN·m高能级强夯置换,采用2.5 m夯锤直径有利于地基加固深度向下发展;夯锤高径比在0.3~0.5时能充分利用夯击能形成承载力均衡的复合地基结构,研究结论可为夯击参数比选提供依据。

In order to reveal the deformation characteristics and foundation reinforcement laws due to dynamic compaction replacement(DCR),the finite difference principle-based arbitrary Lagrange Euler(ALE)method is adopted in the DCR simulation.A three-dimensional dynamic FEM model is established based on the ALE method.The process of foundation reinforcement under single tamping and continuous dynamic compaction replacement is discussed respectively.The influences of various parameters on the reinforcement effects of high-energy DCR are then analyzed and applied in a real project.The research results indicate that the ALE simulation method can describe the flow deformation of gravel layer during DCR,and can be used for simulating continuous dynamic compaction.The absorption of ramming energy due to backfilling gravel is notable that the reinforcement effects of foundation soil can be weakened as consequence.Therefore,the“less filling-more ramming”named DCR strategy is proved to be more reasonable.The rammer diameter,as much as 2.5 m,is beneficial to the increase of the reinforcement depth of foundation soil when the energy level of DCR equals 8000 kN·m.In case of the rammer height-diameter ratio between 0.3 and 0.5,the ramming energy is fully used in order to form composite foundation with even bearing capacity.The conclusions can be used as reference for comparison and selection of construction parameters of DCR.