Overview of Preventive Conservation Research Work on Seismic Mitigation and Subway Vibration Control in Chengdu Museum of China

ABSTRACT

The 2008 Wenchuan earthquake brought numerous issues to the attention of researchers of seismic mitigation in Chinese museums. After the Wenchuan earthquake, the structural design team of Chengdu Museum conducted a series of research projects on seismic mitigation and subway vibration control design of buildings. These projects included the following topics: optimization of design, numerical simulation of seismic performance, analysis of key technologies for the base isolation structure, in-depth studies on structural vibrations caused by the nearby subway, and proposals for reducing structural vibrations. In 2015, after the superstructure of Chengdu Museum was completed, conservators evaluated the safety of permanent exhibitions under earthquake conditions. Seismic protection devices were installed on the showcases according to the preventive conservation requirements for museum collections. Reinforced measures were used for museum collections according to the methods suggested in the document ‘Specification for seismic protection of museum collection’ (WW/T 0069-2015). The conservators also built a systematic platform for earthquake monitoring for museum collections. Preventive conservation studies on seismic protection and subway vibration control in Chengdu Museum are summarized and forecasted.     

城市轨道交通对住房价格影响的计量分析——以南京市地铁1、2号线为例

本文从理论和实证角度,分析验证了城市轨道交通对沿线站点住房价格的影响。首先通过理论分析提出假说,然后基于特征价格方法构建计量分析模型,利用南京市地铁1、2号线站点附近2km范围内二手楼盘数据,实证分析了城市轨道交通地铁对沿线站点住房价格的影响。结果表明:1城市轨道交通对沿线站点住房价格产生了显著的增值效应,不同距离范围影响程度不同,距地铁站点500m以内住房价格比500m以外高出14.3%,1 000m以内住房价格比1 000m以外高出8.9%,1 500m以内住房价格比1 500m以外高出3.9%,当距离范围超过1 500m后,增值效应在统计上不显著;2轨道交通对住房价格的影响程度与距地铁站点直线距离存在着显著的倒"U"形关系,影响程度随距离先增大后减小,在距地铁站点大约320m时影响程度最大;3轨道交通对沿线站点住房价格的影响程度具有显著的分市场效应,对郊区市场的影响程度要远大于主城区市场。     

进度视角下地铁项目施工安全风险的系统动力学分析

在分析地铁施工安全风险影响因素的基础上,从进度的视角构建了地铁项目施工安全风险的系统动力学模型,并收集数据进行模型仿真。通过调整影响进度压力的三个关键变量——期望劳动力、工作强度和加班时间的权重赋值来进行政策模拟。研究结果表明:增加劳动力是降低系统安全和进度风险水平最有效的方式;增加工作强度的方式不可作为首要策略;在不同的系统目标优先度下,管理者对这三个变量应给予差异化的管理排序。     

Numerical Simulation of Dynamic Response of an Existing Subway Station Subjected to Internal Blast Loading

In order to design and retrofit a subway station to resist an internal blast,the distribution of blast loading and its effects on structures should be investigated firstly.In this paper,the behavior of a typical subway station subjected to different internal blast Ioadings was analyzed.It briefly introduced the geometric characteristics and material constitutive model of an existing two-layer and three-span frame subway station.Then three cases of different explosive charges were considered to analyze the dynamic responses of the structure.Finally,the maximum principal stress,displacement and velocity of the columns in the three cases were obtained and discussed.It concluded that the responses of the columns are sensitive to the charge of explosive and the distance from the detonation.It's also found that the stairs between the two layers have significant effects on the distribution of the maximum principal stress of the columns in the upper layer.The explicit dynamic nonlinear finite element software-ANSYS/LS-DYNA was used in this study.     

迷失在无序世界——库弗《街边车祸》的后现代写作体验

短篇小说《街边车祸》极好地体现了库弗后现代小说的创作特色。作者运用戏仿，大量兼容各种亚文学体裁，跨越了高雅文化和通俗文化的疆界，模糊了幻想和现实的界限，化人物为漂移不定的符号。     

盾构法施工技术在我国的应用与发展

21世纪我国隧道与地下工程需求量很大,盾构法施工技术将会在隧道和地下工程得到较多的应用。本文阐述了盾构法的基本原理,介绍了几种主要的盾构型式,叙述了盾构法施工技术在我国的发展状况。     

城市地铁施工预支护方案多目标多层次系统多维模糊决策

在城市地铁区间施工中,预支护方案的选择涉及诸多因素,本文基于地铁工程的特点,综合应用系统工程的模糊数学识别理论与模糊关系优选理论,建立地铁施工预支护方案选择的多目标多层次模糊决策理论模型,以方案的目标特征值作为最低层次的输入,依次以低层次的输出作为高层次的输入,对每一层次进行模糊计算,最后用级别向量的特征值对各个预支护方案进行排序,得出最优方案。通过算例计算得到比较理想的结果,有效地解决受众多模糊性和不确定性因素影响的地铁施工预支护方案的多目标优化决策问题。     

Wave motion of smoke in subway fire environment

Wave motion in subway or tunnel fire is an intrinsic property of smoke.As the pressure of smoke changes with mass of certain power,a kind of linear wave equation for smoke can be derived from the conservation equations of its mass and momentum,under nearly homogeneous zone assumption.The smoke movement of 4 subway fires was simulated with Airpak.By fitting the pressure-mass functions to the simulated data,wave equations of the smoke were derived,and wave motions of smoke were thus validated.It can be seen that smoke wave is a kind of mass wave,whose velocity is inversely proportional to smoke mass,and wave of a bigger fire propagates slower.     

地铁建设安全风险识别与评估研究综述

为促进地铁施工风险管理的进一步研究和实践,以我国国情为基准,从风险人工识别和自动识别两个方面分析目前地铁建设风险识别现状,从评估方法和评估成果两个方面分析地铁风险评估现状,探讨目前地铁建设安全管理存在的问题和挑战。结果表明,地铁建设安全管理研究具有重大理论和实践价值,但目前存在风险管理不完备的问题,在数据获取、综合模型建立、风险因素融合和管理方式转变等方面需要开展深入研究。     

旋喷桩施工技术在深圳地铁盾构加固区中的应用

简要介绍了深圳地铁红岭段的工程概况,对旋喷桩施工的机理及其地层适应性进行了分析,详细阐述盾构区旋喷桩施工技术和方法,通过在深圳地铁红岭段盾构加固区中的应用,达到较好的加固效果,证明了旋喷桩在地基加固的实用性,说明采用高压喷法比较适合城市轨道盾构区加固．