组合桩锤锤击模型的数值分析

Numerical analysis for impact model of a combined pile-hammer

为分析一个锤击周期内两个锤头连续锤击时对打桩锤锤击力的影响,将锤头结构设计为由上、下锤头和中间垫层组成的组合桩锤,用不同的集中质量块表示上锤头、下锤头、砧座和桩帽,用不同的并联的弹簧和阻尼器表示中间垫层和锤垫,用弹簧表示桩垫,用阻尼器表示桩,建立了平衡方程。采用量纲分析法推导出锤击力的数值解,分析了桩锤与垫层的分离情况,比较了组合桩锤各参数和垫层参数对锤击力的影响,并与普通桩锤产生的锤击力进行了比较。结果表明:将锤头设计为组合桩锤结构,使得锤击力波形出现多个峰值,且峰值减小,有效锤击时间加长。

In order to analyze the influence of two rams one by one impact in a cycle on the impact force of a pile- hammer, numerical analysis model for a combined pile-hammer consisting of an upper ram and lower ram was presented. In the model, different lumped masses were taken as an upper ram, a lower ram, an anvil and a pile cap, different springs and dashpots were taken as a middle cushion and a ram cushion, a spring was taken as a pile cushion and a dashpot was taken as a pile. The equilibrium equations were establishe. Numerical solution to the impact force was derived with the dimensional analysis, the separation of a ram from its cushion and the separation of a pile from its cushion were considered, the influence of the combined pile-hammer＇s parameters on the impact force was analyzed, and the impact forces generated by a common pile-hammer and a combined pile-hammer were compared. Results showed that the combined pile-hammer structure makes the impact force have several smaller peaks and the effective impact time be longer.