• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文学位 >Investigation of three-dimensional tunnel responses due to basement excavation.
【24h】

Investigation of three-dimensional tunnel responses due to basement excavation.

机译：对地下室开挖引起的三维隧道响应的研究。

获取原文
获取原文并翻译 | 示例
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

For public convenience, basement excavations for shopping malls and/or car parks areconstructed very close to existing tunnels. Construction of basement may induceunsymmetrical and highly skewed loadings and/or stress changes in an existing tunnel, notonly in the transverse but also in the longitudinal direction of the tunnel. Although thebasement-tunnel interaction has attracted considerable attention recently, it is often simplytreated as a plane strain problem.;This research aims at investigating the fundamental mechanisms of the basement-tunnelinteraction three-dimensionally. Two major research methodologies, i.e., centrifuge modellingand finite element analysis, were adopted. Based on a dimensional analysis of the governingparameters, four centrifuge tests were conducted in dry sand to investigate the influence oftunnel location, sand density and retaining wall stiffness on the three-dimensional tunnelresponses due to basement excavation. Moreover, two tests were carried out in saturated clayto explore long-term tunnel responses due to overlying basement excavation. A continuousaluminium tube (i.e., empty) was used to model existing tunnel. Effects of excavation weresimulated by draining heavy fluid away in-flight. To enhance the fundamental understandingof the basement-tunnel interaction, three-dimensional numerical back-analysis of centrifugetests and systematic parametric study were conducted. The parameters considered on theinteraction in sand included sand density, retaining wall stiffness, excavation geometry,aspect ratio, unloading ratio, tunnel stiffness and joint stiffness ratio.;For the tunnel located directly beneath the basement, heave was induced due to vertical stressrelief. Because of symmetrical stress relief around the tunnel, it was vertically elongated. Asthe relative sand density decreased from 90% to 30%, the maximum heave and tensile straininduced in the tunnel increased by 90% and 80%, respectively. This is because a looser sandhas smaller stiffness. Moreover, it is found that the tensile strain induced along thelongitudinal direction was insensitive to retaining wall stiffness, but that induced along thetransverse direction was significantly reduced by a stiff wall. In addition, the basement-tunnelinteraction at the basement centre reached a plane strain condition when excavation lengthalong the longitudinal tunnel direction was longer than 9 He (final excavation depth). Bothheave and transverse tensile strain of the tunnel exceeded the allowable movement limit andcracking strain when excavation length was longer than 5 He (final excavation depth) andexcavation width was wider than 2 He. For the tunnel located outside the basement, itdemonstrated settlement resulting from inward soil movements behind the wall. Due tounsymmetrical stress relief and shearing, the tunnel was distorted (i.e., elongate towardbasement). The induced tunnel response in this case was less than 35% of the correspondingvalue for the tunnel located directly beneath basement. Thus, it is suggested to construct abasement at a side of tunnel rather than above it. The use of a diaphragm wall reduced themaximum settlements and tensile strains induced in the tunnel by up to 22% and 58%,respectively, compared with the use of a sheet pile wall. This is because a stiffer diaphragmwall can significantly reduce the ground movements behind it.;Because of a smaller initial void ratio in a stiffer clay, induced tunnel heave and tensile strainupon completion of excavation in heavily overconsolidated clay (overconsolidation ratio(OCR) = 6.0) were 25% and 16% smaller than that in lightly overconsolidated clay (OCR =1.7). Due to the dissipation of excess negative pore water pressure, the maximum tunnelheave and tensile strain increased by up to 210% and 50%, respectively, in heavily and lightlyoverconsolidated clays. Observed larger long-term tunnel response in the stiffer clay was dueto shearing induced larger excess negative pore water pressure.
机译：为了公共便利，大型购物中心和/或停车场的地下建筑被建造在非常接近现有隧道的位置。地下室的构造可能会在既有隧道中引起不对称和高度偏斜的荷载和/或应力变化，不仅在隧道的横向而且在隧道的纵向。尽管近来地下室-隧道相互作用引起了广泛的关注，但它通常被简单地视为平面应变问题。本研究旨在从三维角度研究地下室-隧道相互作用的基本机理。采用了两种主要的研究方法，即离心机建模和有限元分析。基于控制参数的尺寸分析，在干砂中进行了四个离心试验，以研究隧道位置，砂密度和挡土墙刚度对地下室开挖引起的三维隧道响应的影响。此外，在饱和黏土中进行了两个测试，以探讨由于地下室开挖引起的长期隧道响应。连续的铝管（即空的）用于模拟现有隧道。通过在飞行中排出重油来模拟开挖的效果。为了增强对地下室-隧道相互作用的基本理解，进行了离心试验的三维数值反分析和系统的参数研究。考虑砂土相互作用的参数包括：砂密度，挡土墙刚度，开挖几何形状，长宽比，卸载比，隧道刚度和接缝刚度比。对于位于地下室正下方的隧道，由于竖向应力释放而引起隆起。由于隧道周围的对称应力释放，它被垂直拉长。随着相对沙子密度从90％降低到30％，隧道中引起的最大起伏和拉伸应变分别增加了90％和80％。这是因为较松的砂具有较小的刚度。此外，发现沿纵向方向引起的拉伸应变对保持壁的刚度不敏感，但是沿横向方向引起的拉伸应变被坚硬的壁显着减小。另外，当沿纵向隧道方向的开挖长度大于9 He（最终开挖深度）时，地下室中心处的地下室-隧道相互作用达到了平面应变条件。当开挖长度大于5 He（最终开挖深度）且开挖宽度大于2 He时，隧道的波动和横向拉伸应变均超过允许的运动极限和开裂应变。对于位于地下室外部的隧道，它表明了墙后向内的土壤运动所导致的沉降。由于不对称的应力释放和剪切作用，隧道变形了（即向基底延伸）。在这种情况下，诱发的隧道响应小于位于地下室正下方的隧道的相应值的35％。因此，建议在隧道的一侧而不是在其上方建造一个地下室。与使用板桩墙相比，使用隔板墙可将隧道中的最大沉降和拉伸应变分别降低22％和58％。这是因为较硬的隔板墙可显着减少其后的地面运动。;由于较硬的粘土中较小的初始空隙率，在严重超固结的粘土中完成开挖时会引起隧道隆起和拉伸应变（超固结比（OCR）= 6.0）分别比轻度超固结的粘土（OCR = 1.7）小25％和16％。由于消散了多余的负孔隙水压力，在重固结和轻度超固结的黏土中，最大的隧道起伏和拉伸应变分别增加了210％和50％。在较硬的黏土中观察到较大的长期隧道响应是由于剪切作用导致较大的过量负孔隙水压力。

著录项

  • 作者

    Shi, Jiangwei.;

  • 作者单位

    Hong Kong University of Science and Technology (Hong Kong).;

  • 授予单位 Hong Kong University of Science and Technology (Hong Kong).;
  • 学科 Civil engineering.
  • 学位 Ph.D.
  • 年度 2015
  • 页码 257 p.
  • 总页数 257
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号