摘要
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 pilehammer,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.
引文
[1]Take W A,Valsangkar A J,Randolph M F.Analytical solution for pile hammer impact[J].Computers and Geotechnics,1999,25(2):57-74.
[2]朱合华,谢永健,王怀忠.打桩锤击解析模型及垫层材料参数的优化[J].同济大学学报(自然科学版),2004,32(7):841-845.ZHU He-hua,XIE Yong-jian,WANG Huai-zhong.Analytical solution for pile hammer impact and application of optimum design technique for determining cushion parameters[J].Journal of Tongji University(Natural Science),2004,32(7):841-845.
[3]Sabellico A R.Pile driver pad[P].US3154155,Oct.27,1964.
[4]Guild C L.Hydraulic cushion block and impact type pile driving hammers[P].US3498391,Mar.3,1970.
[5]Ruppert R W.Pile hammer cushion apparatus[P].US3991833,Nov.16,1976.
[6]杨襄璧,刘德顺,胡均平.撞击回弹问题的理论研究[J].中国有色金属学报,1996,6(4):171-175.YANG Xiang-bi,LIU Des-hun,HU Jun-ping.Theoretical studies on rebound problem of impact[J].The Chinese Journal of Nonferrous Metals,1996,6(4):171-175.
[7]朱萍玉,杨襄璧,刘德顺.基于MATLAB的冲锤反演设计与数控加工初探[J].机械设计与制造,2002,4:81-83.ZHU Ping-yu,YANG Xiang-bi,LIU De-shun.Inverse design of impactors based on matlab[J].Machinery Design&Manufacture,2002,4:81-83.
[8]杨永海,吕景忠,隋振,等.加速下落冲击式液压桩锤设计[J].农业机械学报,2005,36(5):150-152.YANG Yong-hai,LJing-zhong,SUI Zhen,et al.Design of accelerated impact pile hammer[J].Transactions of the Chinese Society for Agricultural Machinery,2005,36(5):450-152.
[9]胡均平,郭勇,宋光伟,等.金属颗粒填充桩锤锤击模型的数值分析[J].中国公路学报,2010,23(2):122-126.HU Jun-ping,GUO Yong,SONG Guang-wei,et al.Numerical analysis for impact model of pile hammer filled with metal particles[J].China Journal of Highway and Transport,2010,23(2):122-126.
[10]Zhang Lei,Gong Xiao-nan,Yang Zhong-xuan,et al.Elastoplastic solutions for single piles under combined vertical and lateral loads[J].J.Cent.South Univ.Technol,2011,18:216-222.
[11]胡育佳.桩基非线性静动力学特性研究[D].上海:上海大学,2008.