饱和地基中波阻板远场被动隔振的二维BEM-FEM耦合分析  

2D BEM-FEM analysis of vibration isolation by using WIB as passive wave barrier in saturated soil

作　　者：时刚[1] 朱超杰 陈既学 SHI Gang;ZHU Chaojie;CHEN Jixue(School of Civil Engineering,Zhengzhou University,Zhengzhou 450001,China)

机构地区：[1]郑州大学土木工程学院,河南郑州450001

出　　处：《世界地震工程》2023年第3期216-226,共11页World Earthquake Engineering

摘　　要：国际上已把振动污染列入“七大环境公害”之一,而波阻板(wave impedance block,简称“WIB”)是低频环境振动污染防治的一种常用手段。针对饱和地基中建(构)筑物下方设置波阻板的远场被动隔振问题,分别采用饱和土半解析BEM对饱和地基和FEM对波阻板进行建模,最终建立了波阻板对入射Rayleigh波隔振的半解析BEM-FEM耦合方程,采用该方法计算分析了波阻板的远场被动隔振效果,并初步探讨了组合式波阻板(由多种材料组成的波阻板)的隔振效果。研究结果表明:在建(构)筑物下方一定深度设置波阻板能够有效降低波阻板上方地表的振动;地表屏蔽区域范围与波阻板设置范围基本吻合。减小波阻板埋深和增大波阻板厚度均能取得更好的隔振效果,而波阻板宽度对隔振效果基本无影响;实际工程设计时,建议波阻板埋深取0.2~0.4λR(λR为Rayleigh波波长)和厚度取0.2~0.3λR,宽度则根据被保护建筑尺寸确定。波阻板材料剪切模量对隔振效果影响较大,增加波阻板材料剪切模量是提高波阻板被动隔振效果最为有效的措施之一。此外,当波阻板由竖向多层材料组成时,建议采用上软下硬方式构建波阻板;当波阻板由多种材料水平分区组成时,地表隔振效果与其下方对应分区的材料性质相对应,可根据实际工程振动控制要求的不同构建多种材料分区的组合式波阻板。The adverse effects of ground vibrations,which are generated by traffic,machine operations and so on,can be eliminated or prevented by using various types of wave barriers,such as wave impedance block(WIB),which can be used to isolate the low-frequency vibrations.This paper presents a study on the problem of the ground vibration isolation by using WIB as passive barriers installed under the protected structure in saturated soil.The analysis is accomplished with the aid of semi-analytical BEM coupled with FEM,and the BEM-FEM equations of the scattering of Rayleigh waves by WIB are put forward.Effects of the relevant parameters on the vibration isolation efficiency are analyzed and discussed in detail.The results show that the WIB can isolate ground vibrations effectively inside the zones above the WIB,and the width of screening zone is similar to that of WIB.Decreasing the embedded depth and increasing the thickness of WIB can all increase the screening efficiency of WIB.Then it’s suggested that the embedded depth and the thickness of WIB should take the value of 0.2~0.4λR(the Rayleigh wavelength)and 0.2~0.3λR,respectively,and the width of WIB should be designed according to the protected structure.Further,increasing the shear modulus of WIB maybe the optimum measure to obtain better isolation efficiency.Moreover,when WIB is made up of several layers with different materials,it is suggested that the softer layers should be constructed above the harder ones,while for WIB which is made up of several blocks with different materials in horizontal,the vibration isolation effectiveness of different surface region is dependent on the materials of WIB beneath the region.

关 键 词：饱和地基 波阻板 RAYLEIGH波 半解析BEM-FEM耦合方法 远场被动隔振 隔振效果 

分 类 号：TU435[建筑科学—岩土工程]