低、多层房屋基底软土垫层隔震研究

Research on isolated low-rise buildings using a thin soft soil layer

为了发展适用于低、多层房屋的隔震方法,本文提出了基底软土薄层隔震的思想和详细构造。通过建立包含基底软土垫层的地基-基础-上部结构体系整体有限元模型,考虑软土垫层的几何特性及动力学特性参数的变化,分析了软土垫层埋深、厚度、端部宽度以及软土层最大动剪模量、软土层横观各向同性特性对上部结构动力反应的影响。结果表明:(1)基底软土薄层将使得上部结构的加速度幅值减小,并且降低的程度随着软土动剪模量的降低而增大;(2)软土层动力非线性的发展和横观各向同性特性有助于其隔震效应的提高;(3)当在实践可能的范围内变化时,基础埋深、基底软土层厚度、基础端部软土层宽度等决定隔震垫层工程量大小的参数对软土层隔震效应影响较小;(4)基底软土层隔震效应随着上部结构自身刚度增大而增加。本文研究结果表明基底软土隔震是一种适用于低、多层房屋的简单廉价的隔震方法,且具有较好的鲁棒性。

For the purpose of developing effective and economic base isolation methods for low-rise buildings,the idea,which includes a thin soft layer between the foundation and the underlying soil as a vibration isolator,is studied in this paper.Firstly,the finite element analysis model,which takes the soil-inter soft layer-foundation-superstructure system into consideration,is built up,then the effects of variations of the geometric and mechanical parameters of the inter-soft-layer are investigated.Numerical results indicate that:(1) the imposing of an inter-softlayer can reduce the amplitude of acceleration of the structure,and the degree of reduction increases with the decreasing of soft soil shear modulus;(2) the dynamic nonlinearity of soils and the transversely isotropic characteristics of the soft soil layer are beneficial to the improvement of isolation effect;(3) the geometric parameters of the inter-soft-layer,i.e.,the buried depth of foundation and the thickness of soft-inter-layer beneath and beside the foundation,affect the isolation effect slightly;(4) the isolation effect of the soft-inter-layer increases with the superstructure stiffness.These results demonstrate that a thin soft-soil-layer between the foundation and the underlying soil is an isolation method that is simple and cost effective and is particularly suitable for low-rise buildings.