Considering dynamic soil structure interaction (SSI) effects on seismic isolation retrofit efficiency and the importance of natural frequency ratio   总被引：3，自引：0，他引：3  

Edward H. Stehmeyer  III  Dimitris C. Rizos   《Soil Dynamics and Earthquake Engineering》2008,28(6):468-479

This paper utilizes and expands on existing coupled BEM–FEM (finite element method) methods for the investigation of the effects of soil structure interaction (SSI) on both an un-retrofitted and seismically isolated typical bridge structure. A simple numerical model of the bridge and surrounding soil is formulated and excited by an earthquake excitation. Utilizing Newmark's β FEM solution method along with the closed form B-spline BIRF method, the structural damped period, composite damping ratio, pier relative displacement, and base shear demand are monitored. From these results, the effects of SSI on this structure are identified. Additionally, the importance of the relative rigidity between the soil-foundation system and the bridge structure is also investigated. The results of the studies indicate that the response of the complete structure system considered is affected by the inclusion of SSI effects. Furthermore, the efficiency of the isolation measures designed using fixed base conditions is decreased by considering SSI over a certain relative rigidity range that is quantified using the structure to soil-foundation natural frequency ratio.  相似文献   

某特深基坑支护的非线性三维有限元分析   总被引：37，自引：4，他引：33  

宋二祥  娄鹏  陆新征  沈伟 《岩土力学》2004,25(4):538-543

讨论了润扬长江大桥北锚碇基础施工开挖中50 m特深基坑的三维非线性有限元分析,介绍了工程的有关情况,讨论了其计算模型和参数取值,给出主要计算结果并对有关影响因素进行了分析,在此基础上对该基坑支护的设计作出评价,最后结合施工结果讨论了计算分析的可靠性。  相似文献   

旁压试验在苏通大桥地质勘察工程中的应用   总被引：8，自引：2，他引：6  

汪稔  胡建华 《岩土力学》2003,24(6):887-891

详细介绍了旁压试验的使用方法,以及受潮汐影响的大桥勘察旁压原位测试中的特殊处理措施,分析了旁压试验中各强度参数指标的处理方法和原则,并运用这些方法和原则处理了苏通大桥旁压试验的强度参数指标,为大桥的设计提供了设计强度参数,也可为同类工程提供参考意义。  相似文献   

Palaeotopography of the northern portion of the Telychian (Silurian) turbidite basin in central Wales     

D.M.D. James 《Geological Journal》2005,40(5):593-601

New palaeocurrent data from the country northeast and southwest of Corris (central Wales) indicate that Telychian sandstones in the Devil's Bridge Formation hereabouts were transported from both the northeast and northwest, consistent with topographical control by down‐to‐southeast movement on the Bala Lineament. This conclusion is supported by considerations of thickness variation and by evidence for listric detachment faulting in the formation at Bwlch y Groes. Towards Plynlimon, flow is broadly southerly and suggests confinement by the northward extension of the Bronnant Fault. A facies and palaeocurrent map is presented for the utilis sub‐Biozone of the Telychian which links with work by the British Geological Survey between Aberyswyth and Rhayader where, by contrast, palaeoflow is to the NNW. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

公民科学素质视角下的防震减灾科普研究——以日本和美国为例     

陆文静  郭浩然  孙春仙  夏文君 《震灾防御技术》2019,14(4):882-889

防震减灾科普教育是提升公民防震减灾科学素质的重要途经。日本和美国是在防震减灾科普教育方面走在世界前列的国家。本文通过研究日本和美国关于公民防震减灾科学素质建设文献资料，分类归纳日本和美国公民防震减灾科学素质建设的历史背景、发展特点及主要路径，由此对我国公民防震减灾科学素质建设提出思考和建议。  相似文献   

不同约束方式对匝道桥动力特性的影响研究   总被引：1，自引：0，他引：1  

王克海  张盼盼  吴刚  鲁冠亚 《震灾防御技术》2018,13(4):756-763

近年来，地震作用下的匝道桥表现出较高的地震易损性。为建立匝道桥的有效约束方式，以减小其地震损伤，本文基于汶川地震中连续梁桥约束方式的调研结果，建立了4种不同匝道桥支座约束方式，并以石家庄石环线某匝道桥为例，对比分析了不同约束方式下匝道桥的自振特性及地震响应。结果表明:板式橡胶支座具有一定的剪切变形能力，可降低桥墩与支座组成的体系刚度，有效分散了上部结构的地震惯性力，保护了下部结构，但应注意其引起的较大主梁位移；固定支座或墩梁固结形式会放大桥墩受力，增加下部结构的损坏，不宜设置在高度较矮、刚度较大的桥墩上；双层挡块和垫石凹槽分级限位支座具有较好的限位能力，并可耗散部分地震能量。  相似文献   

新亚欧大陆桥新疆段暴雨灾变事件的灰色预测   总被引：1，自引：1，他引：0  

陈亚宁  杨思全 《干旱区地理》1999,22(4):77-82

通过对新亚欧大陆桥新疆段水害严重区段暴雨灾变事件的分析,确定暴雨灾变事件的临界雨强,并运用灰色灾变预测方法,根据暴雨灾变序列确立相应的灾变年份序列,运用ＧＭ（１,１）模型,分别求出灾变年份序列的ＧＭ（１,１）序号响应式和灾变年份预测式。  相似文献   

厦漳跨海大桥施工控制网复测     

吴迪军  张建军  李书银 《地理空间信息》2010,8(3):103-105

介绍厦漳跨海大桥施工控制网复测的方法、技术要点及成果精度等情况,通过复测成果与建网成果的比较分析,对施工控制点的稳定性进行了评价,提出了施工期间控制点稳定性检测的建议。  相似文献   

EH4电磁成像系统在高速公路长大深埋隧道勘察中的应用研究   总被引：13，自引：1，他引：12  

孙英勋 《工程地质学报》2005,13(4):546-550

EH4电磁成像系统是一套双源型电磁法数据自动采集和处理的物探系统,它是CSAMT和MT的结合体。本文介绍了EH4的原理、特点、工作方法和资料处理。该系统首次运用于高速公路长大深埋隧道勘察中,结合其他手段,成功解译出了隧道的软弱层、地下水及断层破碎带的位置,为划分隧道围岩类别提供了较好的依据,同时也为高速公路长大深埋隧道提供了一种新的勘察方法。  相似文献   

Enhancing PIV image and fractal descriptor for velocity and shear stresses propagation around a circular pier     

Alireza Keshavarzi  James Ball 《地学前缘(英文版)》2017,8(4):869-883

In this study,the fractal dimensions of velocity fluctuations and the Reynolds shear stresses propagation for flow around a circular bridge pier are presented.In the study reported herein,the fractal dimension of velocity fluctuations(u′,v′,w′) and the Reynolds shear stresses(u′v′ and u′w′) of flow around a bridge pier were computed using a Fractal Interpolation Function(FIF) algorithm.The velocity fluctuations of flow along a horizontal plane above the bed were measured using Acoustic Doppler Velocity meter(ADV)and Particle Image Velocimetry(P1V).The PIV is a powerful technique which enables us to attain high resolution spatial and temporal information of turbulent flow using instantaneous time snapshots.In this study,PIV was used for detection of high resolution fractal scaling around a bridge pier.The results showed that the fractal dimension of flow fluctuated significantly in the longitudinal and transverse directions in the vicinity of the pier.It was also found that the fractal dimension of velocity fluctuations and shear stresses increased rapidly at vicinity of pier at downstream whereas it remained approximately unchanged far downstream of the pier.The higher value of fractal dimension was found at a distance equal to one times of the pier diameter in the back of the pier.Furthermore,the average fractal dimension for the streamwise and transverse velocity fluctuations decreased from the centreline to the side wall of the flume.Finally,the results from ADV measurement were consistent with the result from PIV,therefore,the ADV enables to detect turbulent characteristics of flow around a circular bridge pier.  相似文献