饱和土中单桩复合地基上块体的速度导纳特性分析
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摘要
根据饱和土弹性波动方程,建立了饱和地基轴对称竖向振动问题的一种有限元-无限元耦合解法并编制了计算程序,其精度应用Lamb问题的理论解来进行检验。参数分析结果表明,地基土的渗透性对单桩复合地基上块体竖向振动速度导纳的低频特性及共振频率影响甚微,但会使高频下的速度导纳幅值有所增大。该方法对饱和土中单桩复合地基动测技术的研究与应用具有一定的理论指导作用。
Based on the dynamic governing equations of elastic waves, a hybrid finite-infinite element method is proposed for analyzing axisymmetrically vertical vibration of saturated media. Using the compiled program, the surface vertical displacements of the air-saturated ground (dry soil) are calculated under a surface point excitation, which are agree well with the theoretical solutions of the Lamb’s problem. The velocity admittance curves of block on single-piled composite foundations in saturated soil with varied permeability are calculated with the conclusions that the soil permeability will have few effects on the velocity admittances of block at low frequencies and on the resonant frequency, while the velocity admittances of block at high frequencies will increase with increasing permeability coefficient of soil. The conclusion will be of guide significance on further research of dynamic test method for engineering parameters of composite foundations in saturated soil.
Based on the dynamic governing equations of elastic waves, a hybrid finite-infinite element method is proposed for analyzing axisymmetrically vertical vibration of saturated media. Using the compiled program, the surface vertical displacements of the air-saturated ground (dry soil) are calculated under a surface point excitation, which are agree well with the theoretical solutions of the Lamb’s problem. The velocity admittance curves of block on single-piled composite foundations in saturated soil with varied permeability are calculated with the conclusions that the soil permeability will have few effects on the velocity admittances of block at low frequencies and on the resonant frequency, while the velocity admittances of block at high frequencies will increase with increasing permeability coefficient of soil. The conclusion will be of guide significance on further research of dynamic test method for engineering parameters of composite foundations in saturated soil.
引文
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[8]宋春雨,陈龙珠,夏宇峰.单桩复合地基上块体的竖向振动特性[J].地震工程与工程振动,2004,24(2):134-140.SONG Chun-yu,CHEN Long-zhu,XIA Yu-feng.Dynamics of block on composite foundation with single pile[J].Earthquake Engineering and Engineering Vibration,2004,24(2):134-140.
[9]Biot MA.The theory of propagation of elastic waves in a fluid-saturated porous solid[J].The Journal of Acoustical Society of America,1956,28:168-191.
[10]Philippacopoulos AJ.Waves in a partially saturated layered half space:analytic formulation[J].Bulletin of the Seismological Society of America,1987,77(5):1838-1853.
[11]严人觉,王贻荪,韩清宇.动力基础半空间理论概论[M].北京:中国建筑工业出版社,1981.
[2]徐攸在.动测技术在复合地基承载力测定中的应用[J].工业建筑,1993,3(4):3-5.XU You-zai.The application of dynamic testing to determining bearing capacity of composite soil founda-tion[J].Industrial Construction,1993,3(4):3-5.
[3]Bettess P.Infinite elements[J].International Journal of Numerical Method for Engineering,1977,11:53-64.
[4]Medina F,et al.Infinite elements for elastodynamics[J].Earthquake Engineering and Structure Dynamics,1982,10:699-709.
[5]赵崇斌,张楚汉,张光斗.工程中的无穷元方法及其进展[J].陕西机械学院学报,1989,5(1):98-106.ZHAO Chong-bin,ZHANG Chu-han,ZHANG Guang-dou.Application of infinite method in engineering and its development[J].Journal of Shaanxi Institute of Mechanical Engineering,1989,5(1):98-106.
[6]赵崇斌,张楚汉,张光斗.地基无限域的动力模拟:有限元与无穷元耦合模型[J].水利学报,1990,21(6):20-27.ZHAO Chong-bin,ZHANG Chu-han,ZHANG Guang-dou.Dynamic simulation of infinite foundations[J].Journal of Hydraulic Engineering,1900,21(6):20-27.
[7]Khalili N,Yazdchi M,et al.Wave propagation analysis of two-phase saturated porous media using coupled finite-infinite element method[J].Soil Dynamics and Earthquake Engineering,1999,18:533-553.
[8]宋春雨,陈龙珠,夏宇峰.单桩复合地基上块体的竖向振动特性[J].地震工程与工程振动,2004,24(2):134-140.SONG Chun-yu,CHEN Long-zhu,XIA Yu-feng.Dynamics of block on composite foundation with single pile[J].Earthquake Engineering and Engineering Vibration,2004,24(2):134-140.
[9]Biot MA.The theory of propagation of elastic waves in a fluid-saturated porous solid[J].The Journal of Acoustical Society of America,1956,28:168-191.
[10]Philippacopoulos AJ.Waves in a partially saturated layered half space:analytic formulation[J].Bulletin of the Seismological Society of America,1987,77(5):1838-1853.
[11]严人觉,王贻荪,韩清宇.动力基础半空间理论概论[M].北京:中国建筑工业出版社,1981.
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