成层土中桩土耦合扭转振动特性理论研究
|
摘要
假设桩周土层为成层黏弹性体,土体材料阻尼为黏性阻尼,从三维轴对称角度出发,对任意激振扭矩作用下,成层土中完整桩与土扭转耦合振动时的桩顶振动特性进行了理论研究。首先建立定解问题,然后利用拉氏变换求解得到其振动角位移的形式解,并利用桩土接触界面处的连续条件来考虑桩土耦合作用,使用桩段阻抗函数的传递性进行逐层递推求解,最终得到桩顶频域和时域响应的理论解。通过参数影响分析研究发现,成层土中桩顶复刚度主要受上部土层动力特性及性质影响;随着上层土模量增大桩顶复刚度的刚度部分也相应增大,阻尼部分相应减小。成层土由于土层模量变化,桩的导纳曲线有大峰夹小峰循环的特征。当上层土模量大于下层土模量时,在土层分界面时域波形与初始脉冲反向,反之则同向,土模量突变导致的时域波形的特征反射较平缓,幅度不大。
Considering the interaction between visco-elastic layered soils and integral pile,the dynamic response at the pile head to an arbitrary dynamic load is theoretically investigated.By Laplace transforms and the transmit property of impedance function,the analytical expression of the impedance function and displacement and velocity response function at the pile head in frequency domain and in time domain are derived.The characteristic of interaction between soil layers and pile is theoretically investigated.The results indicate that dynamic characteristics of upper layer soil are major factors that affect the complex stiffness of pile.Pile stiffness increases and damping decreases with increasing modulus of upper soil.Because of the change of soil modulus,admittance curves of pile have cycle characteristics which have big peak and small peak.When the modulus of upper soil is higher than that of lower layer soil,the reflection wave shape in time domain at soil division surface and initial pulses are on the contrary.Conversely,they are the same.In genaral,reflection wave shape in time domain at soil division surface is flat and the amplitude is not very large.
Considering the interaction between visco-elastic layered soils and integral pile,the dynamic response at the pile head to an arbitrary dynamic load is theoretically investigated.By Laplace transforms and the transmit property of impedance function,the analytical expression of the impedance function and displacement and velocity response function at the pile head in frequency domain and in time domain are derived.The characteristic of interaction between soil layers and pile is theoretically investigated.The results indicate that dynamic characteristics of upper layer soil are major factors that affect the complex stiffness of pile.Pile stiffness increases and damping decreases with increasing modulus of upper soil.Because of the change of soil modulus,admittance curves of pile have cycle characteristics which have big peak and small peak.When the modulus of upper soil is higher than that of lower layer soil,the reflection wave shape in time domain at soil division surface and initial pulses are on the contrary.Conversely,they are the same.In genaral,reflection wave shape in time domain at soil division surface is flat and the amplitude is not very large.
引文
[1]王腾,王奎华,谢康和.成层土中桩的纵向振动理论研究及应用[J].土木工程学报,2002,35(1):83-87.
[2]刘东甲,周安,刘煜洲.有限长完整桩中的扭转波[J].应用力学学报,2005,22(2):258-263.
[3]Chang Derwen,Roesset J M,Wen Chanhua.Atime-domain viscous damping model based on frequency dependent damping ratios[J].Soil Dy-namics Earthquake Engng,2000,19:551-558.
[4]Militano G,Rajapakse R K N D.Dynamic response of a pile in a multi-layered soil to transient torsional and axial loading[J].Geotechnique,1999,49(1):91-109.
[5]Nogami T,Novak M.Soil-pile interaction in vertical vibration[J].Earthq.Engng.Stuct.Dyn.,1976,4:277-293.
[6]Muki R,Sternberg E.Elastostatic load-transfer to a half-space from a partially embedded axially loaded rod[J].Int J Solids Struct,1970,6:69-90.
[7]Zeng X,Rajapakse R KND.Dynamic axial load transfer fromelastic bar to poroelastic medium[J].J.of Engng.Mech.,1999,125(9):1048-1055.
[8]胡昌斌,王奎华,谢康和.考虑桩土相互作用效应的桩顶纵向振动时域响应分析[J].计算力学学报,2004,21(4):392-399.
[9]胡昌斌,张涛.基于平面应变简化假定的桩扭转振动理论精度研究[J].地震工程与工程振动,2008,28(3):122-130.
[10]胡昌斌张涛.桩与黏性阻尼土耦合扭转振动时桩顶时域响应研究[J].振动工程学报,2006,19(3):404-410.
[11]阙仁波王奎华.考虑土体三维波动效应时弹性支承桩的振动理论及其应用[J].计算力学学报,2005,22(6):658-665.
[12]李强,王奎华,谢康和.饱和土中端承桩纵向振动特性研究[J].力学学报,2004,36(4):435-442.
[13]Lin Meei-Ling,Huang Tsan-Hwei,You Jeng-Chie.The effects of frequency on damping properties of sand[J].Soil Dynamics EarthquakeEngng,1996,15:269-278.
[14]孔德森,栾茂田,杨庆.桩土相互作用分析中的动力Winkler模型研究评述[J].世界地震工程,2005,21(1):12-17.
[15]栾茂田,孔德森.单桩竖向动力阻抗计算方法及其影响因素分析[J].振动工程学报,2004,17(4):500-505.
[16]Meymand P J.Shaking table scale model tests of nonlinear soil-pile-superstructure interaction in soft Clay[D].Berkeley:University of Califor-nia,1998.
[17]Veletsos AS,Damodaran Nair VV.Torsional vibration of viscoelastic foundations[J].Journal of Geotechnical Engineering,1974,100(3):225-246.
[2]刘东甲,周安,刘煜洲.有限长完整桩中的扭转波[J].应用力学学报,2005,22(2):258-263.
[3]Chang Derwen,Roesset J M,Wen Chanhua.Atime-domain viscous damping model based on frequency dependent damping ratios[J].Soil Dy-namics Earthquake Engng,2000,19:551-558.
[4]Militano G,Rajapakse R K N D.Dynamic response of a pile in a multi-layered soil to transient torsional and axial loading[J].Geotechnique,1999,49(1):91-109.
[5]Nogami T,Novak M.Soil-pile interaction in vertical vibration[J].Earthq.Engng.Stuct.Dyn.,1976,4:277-293.
[6]Muki R,Sternberg E.Elastostatic load-transfer to a half-space from a partially embedded axially loaded rod[J].Int J Solids Struct,1970,6:69-90.
[7]Zeng X,Rajapakse R KND.Dynamic axial load transfer fromelastic bar to poroelastic medium[J].J.of Engng.Mech.,1999,125(9):1048-1055.
[8]胡昌斌,王奎华,谢康和.考虑桩土相互作用效应的桩顶纵向振动时域响应分析[J].计算力学学报,2004,21(4):392-399.
[9]胡昌斌,张涛.基于平面应变简化假定的桩扭转振动理论精度研究[J].地震工程与工程振动,2008,28(3):122-130.
[10]胡昌斌张涛.桩与黏性阻尼土耦合扭转振动时桩顶时域响应研究[J].振动工程学报,2006,19(3):404-410.
[11]阙仁波王奎华.考虑土体三维波动效应时弹性支承桩的振动理论及其应用[J].计算力学学报,2005,22(6):658-665.
[12]李强,王奎华,谢康和.饱和土中端承桩纵向振动特性研究[J].力学学报,2004,36(4):435-442.
[13]Lin Meei-Ling,Huang Tsan-Hwei,You Jeng-Chie.The effects of frequency on damping properties of sand[J].Soil Dynamics EarthquakeEngng,1996,15:269-278.
[14]孔德森,栾茂田,杨庆.桩土相互作用分析中的动力Winkler模型研究评述[J].世界地震工程,2005,21(1):12-17.
[15]栾茂田,孔德森.单桩竖向动力阻抗计算方法及其影响因素分析[J].振动工程学报,2004,17(4):500-505.
[16]Meymand P J.Shaking table scale model tests of nonlinear soil-pile-superstructure interaction in soft Clay[D].Berkeley:University of Califor-nia,1998.
[17]Veletsos AS,Damodaran Nair VV.Torsional vibration of viscoelastic foundations[J].Journal of Geotechnical Engineering,1974,100(3):225-246.
版权所有：© 2023 中国地质图书馆 中国地质调查局地学文献中心