二维饱和地基中空沟主动隔振分析
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摘要
根据饱和土Biot理论,在频域内提出了一种适用于弹性波波动问题的有限元-无限元解法,其中有限单元用于近场介质的模拟,而形函数基于一维解析解答的无限单元则被用于人工边界,它可反映波传递到无限远处的特性;应用该法计算算例,以证明其有效性与正确性。在此基础上,对饱和地基中空沟主动隔振效果进行了详细的数值分析,结果表明,空沟深度是影响隔振效果的主要因素,一般沟深越大,隔振效果越好;当沟深一定时,空沟到振源的距离不宜超过1.5倍饱和土剪切波长;空沟的宽度对隔振效果的影响相对较小。
According to the Biot theory in saturated soil,a finite-infinite element method in frequency domain is put forward for analyzing elastic wave propagation.The finite element is utilized to model the near-field medium and the infinite element with shape functions based on analytical solutions is used on the artificial boundary,which can represent wave extending to infinity in far-field.By means of proposed method,a numerical example is presented to demonstrate the effectiveness and accuracy of the method.The parametric study is conducted herein in detail for screening effects of active isolation by open trench in saturated ground.The results show that the isolation effectiveness of open trench is mainly related to the depth of the open trench.Usually increasing the depth gives rise to improving isolation effectiveness.When the depth of the open trench is determined,the distance between the trench and vibration source should not exceed 1.5 times of shear wavelength of saturated ground.Furthermore,the width of open trench has little influence on the screening effectiveness relatively.
According to the Biot theory in saturated soil,a finite-infinite element method in frequency domain is put forward for analyzing elastic wave propagation.The finite element is utilized to model the near-field medium and the infinite element with shape functions based on analytical solutions is used on the artificial boundary,which can represent wave extending to infinity in far-field.By means of proposed method,a numerical example is presented to demonstrate the effectiveness and accuracy of the method.The parametric study is conducted herein in detail for screening effects of active isolation by open trench in saturated ground.The results show that the isolation effectiveness of open trench is mainly related to the depth of the open trench.Usually increasing the depth gives rise to improving isolation effectiveness.When the depth of the open trench is determined,the distance between the trench and vibration source should not exceed 1.5 times of shear wavelength of saturated ground.Furthermore,the width of open trench has little influence on the screening effectiveness relatively.
引文
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[11]KHALILI N,YAZDCHI M,VALLIAPPAN S.Wavepropagation analysis of two-phase saturated porous mediausing coupled finite-infinite element method[J].SoilDynamics and Earthquake Engineering,1999,18(8):533-553.
[2]时刚,高广运.饱和地基中单排桩远场被动隔振研究[J].振动工程学报,2010,23(5):546-553.SHI Gang,GAO Guang-yun.Three-dimensional analysisof a row of piles as passive barriers in saturated soil[J].Journal of Vibration Engineering,2010,23(5):546-553.
[3]时刚,高广运.饱和土半解析边界元法及在双排桩被动隔振中的应用[J].岩土力学,2010,32(增刊2):59-64.SHI Gang,GAO Guang-yun.Semi-analytical boundaryelement method in saturated soil and its application toanalysis of double row of piles as passive barriers[J].Rock and Soil Mechanics,2010,32(Supp.2):59-64.
[4]何俊锋.2.5维有限元法分析列车运行引起的地面动力特性及沉降[D].上海:同济大学,2010.
[5]高广运,何俊锋,李宁,等.饱和地基上列车运行引起的地面振动隔振分析[J].岩土力学,2011,32(7):2191-2198.GAO Guang-yun,HE Jun-feng,LI Ning,et al.Analysisof isolating ground vibration induced by trains running onsaturated ground[J].Rock and Soil Mechanics,2011,32(7):2191-2198.
[6]徐斌.移动荷载引起饱和土动力响应及排桩隔振研究[D].上海:上海交通大学,2009.
[7]LU J F,XU B,WANG J H.A numerical model for theisolation of moving-load induced vibrations by pile rowsembedded in layered porous media[J].InternationalJournal of Solids and Structures,2009,46(21):3771-3781.
[8]CAI Y Q,DING G Y,XU C J.Amplitude reduction ofelastic waves by a row of piles in poroelastic soil[J].Computers and Geotechnics,2009,36(3):463-473.
[9]KHALILI N,VALLIAPPAN S,TABATABAEE Y J,et al.1D infinite element for dynamic problems in saturatedporous media[J].Communications in NumericalMethods in Engineering,1997,13(9):727-738.
[10]BIOT M A.Theory of elastic waves in fluid-saturatedporous solid:Low-frequency range[J].Journal of theAcoustical Society of America,1956,28(2):168-178.
[11]KHALILI N,YAZDCHI M,VALLIAPPAN S.Wavepropagation analysis of two-phase saturated porous mediausing coupled finite-infinite element method[J].SoilDynamics and Earthquake Engineering,1999,18(8):533-553.