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571.
In this paper, a numerical approach for the prediction of vibrations induced in buildings due to railway traffic in tunnel is proposed. The numerical method is based on a sub-structuring approach, where the train is simulated by a multi-body model; the track–tunnel–ground system is modeled by a 2.5D FEM–PML approach; and the building by resource to a 3D FEM method. The coupling of the building to the ground is established taking into account the soil–structure-interaction (SSI). The methodology proposed allows dealing with the three-dimensional characteristics of the problem with a reasonable computational effort. Using the proposed model, a numerical study is developed in order to better discern the impact of the use of floating slabs systems for the isolation of vibrations in the tunnel on the dynamic response of a building located in the surrounding of the tunnel. The comparison between isolated and non-isolated scenarios allowed concluding that the mats stiffness is a key parameter on the efficiency of floating slab systems. Furthermore, it was found that the selection of the stiffness of the mats should be performed carefully in order to avoid amplification of vertical vibrations of the slabs of the building. 相似文献
572.
桩-网复合地基同时具备竖向增强和水平向增强两种加固形式的优点,由桩、网、土三者共同协调作用,有效分担路堤荷载,是一种作用机理复杂的地基加固方法。通过对某客运专线红粘土桩-网复合地基试验段进行的现场测试试验,对复合地基的基底土压力、土工格栅变形、孔隙水压力以及桩土沉降量等方面的测试,得出红粘土复合地基需要在桩、网、桩间土通过一个反复的作用过程才能达到稳定状态等结论,将有助于深入研究桩-网复合地基加固机理,并为进一步完善桩-网复合地基设计方法提供依据。 相似文献
573.
新疆公路交通基础设施建设对经济增长的贡献分析 总被引:13,自引:1,他引:12
投入产出分析与ESDA结合可能对拓宽投入产出分析的发展领域具有重要意义。试将投入产出分析与ESDA相结合,就1997-2008 年新疆公路交通基础设施建设(以下简称新疆交通建设) 对经济增长的贡献进行分析,主要结论为:① 新疆交通建设促进经济增长的机理主要在于:以相对较小的劳动力消耗实现较大的后向波及部门商品价值转移,并由此产生更大比重的前向波及作用、消费波及作用,乘数效应是新疆交通建设促进经济增长、拉动内需的重要枢纽;② 在新疆区域经济极化-扩散过程的大背景下、大尺度中,各地州市域交通建设对经济增长贡献空间相关性逐步增强,呈明显的扩散效应,各地州市域交通建设经济贡献率呈空间正相关性,空间上的反极化效应显著;③ 新疆交通建设对经济增长贡献既满足了中心区域的极化需要,也通过三级垂直波及作用模式的横向扩散促进了外围区域经济社会发展,使外围区域各族群众通过直接或间接参与交通建设活动而首先分享到了改革与发展的部分成果。研究表明,将投入产出分析与ESDA相结合,对初步揭示交通建设促进经济增长的作用机理及空间分异、空间相互作用具有一定作用。 相似文献
574.
High‐tech equipments engaged in the production of ultra‐precision products have very stringent vibration criteria for their functionality in normal operation conditions and their safety during an earthquake. Most previous investigations were based on simplified planar models of building structures, despite the fact that real ground motions and structures are always three‐dimensional. This paper hence presents a three‐dimensional analytical study of a hybrid platform on which high‐tech equipments are mounted for their vibration mitigation. The design methodology of the hybrid platform proposed in this study is based on dual‐level performance objectives for high‐tech equipments: safety against seismic hazard and functionality against traffic‐induced microvibration. The passive devices (represented by springs and viscous dampers) and the active actuators are designed, respectively, to meet vibration criteria corresponding to safety level and functionality level. A prototype three‐story building with high‐tech equipments installed on the second floor is selected in the case study to evaluate the effectiveness of the hybrid platform. The optimal location of the platform on the second building floor is determined during the design procedure in terms of the minimal H 2 cost function of absolute velocity response. The simulation of the coupled actuator‐platform‐building system subjected to three‐dimensional ground motions indicates that the optimally designed hybrid platform can well achieve the dual target performance and effectively mitigate vibration at both ground motion levels. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
575.
Effect of vehicle weight on natural frequencies of bridges measured from traffic-induced vibration 总被引:2,自引:0,他引:2
Chul-Young?KimEmail author Dae-Sung?Jung Nam-Sik?Kim Soon-Duck?Kwon Maria?Q.?Feng 《地震工程与工程振动(英文版)》2003,2(1):109-115
Recently, ambient vibration test (AVT) is widely used to estimate dynamic characteristics of large civil structures. Dynamic
characteristics can be affected by various environmental factors such as humidity, intensity of wind, and temperature. Besides
these environmental conditions, the mass of vehicles may change the measured values when traffic-induced vibration is used
as a source of AVT for bridges. The effect of vehicle mass on dynamic characteristics is investigated through traffic-induced
vibration tests on three bridges; (1) three-span suspension bridge (128m +404m + 128m), (2) five-span continuous steel box
girder bridge (59m + 3@95m + 59m), (3) simply supported plate girder bridge (46m). Acceleration histories of each measurement
location under normal traffic are recorded for 30 minutes at field. These recorded histories are divided into individual vibrations
and are combined into two groups according to the level of vibration ; one by heavy vehicles such as trucks and buses and
the other by light vehicles such as passenger cars. Separate processing of the two groups of signals shows that, for the middle
and long-span bridges, the difference can be hardly detected, but, for the short span bridges whose mass is relatively small,
the measured natural frequencies can change up to 5.4%.
Supported by: the Ministry of Construction and Transportation, Korea Highway Corporation and Hyundai E&C Co. Ltd. under Project
No. R&D/970003-2. 相似文献
576.
基于游客行为的旅游线路组织研究 总被引:11,自引:0,他引:11
马晓龙 《地理与地理信息科学》2005,21(2):98-101
为寻求合理的旅游线路组织方式,指导区域旅游线路体系建设和旅行社线路组织,该文对国内外旅游线路的组织模式进行总结和评价,认为现有线路组织模式未能与我国国情衔接,缺乏实用性和对游客行为特征的考虑。提出基于游客行为特征的旅游线路组织模式,并分析影响这种旅游线路组织的要素及相互作用关系。以西安旅游区为例,通过对资源分布特征和旅游线路组织现状的分析,以该模型为基础,优化和构建了西安旅游区旅游线路组织的宏观发展框架。 相似文献
577.
578.
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580.
基于GIS的区域交通通达性模型的研究与开发 总被引:1,自引:0,他引:1
SONG Qin-chang LIU Wan-song REN You-gui QIAO Jin-hai XIAO Yang XU Jun-qiang College of GeoExploration Science Technology Jilin University Changchun China 《吉林大学学报(地球科学版)》2006,(Z2)
介绍了基于栅格数据的区域通达性模型的设计和实现思路,提出了以GIS为基础平台,以地图为载体,整合各种资源,建立区域通达度模型的方法,讨论了基于栅格数据的最佳路径分析方法,综合考虑各种影响因素,通过计算最小累加费用值确定最佳路径。 相似文献