【作者】 田力；

【导师】 李忠献；

【作者基本信息】 天津大学 ， 结构工程， 2004， 博士

【摘要】 城市地下隧道内的剧烈爆炸,往往会给隧道衬砌、周围土体以及附近地面的结构物造成严重损坏。为揭示各类地表结构在该事故引发的地下爆炸波作用下的动力响应规律,探讨能降低其响应的一些减隔震措施及其效果,本文针对多层建筑、大跨屋盖结构和连续梁桥等三类结构遭受地下爆炸波冲击的动力响应及其滑移隔震效果进行了系统的分析研究,主要的创新工作与成果包括以下几个方面:(1)引入多种数值模拟方法,采用子结构理论建立起包含地下隧道、半无限土体和各类地表结构(分为非隔震和滑移隔震两种情形)在内的各个耦合体系模型。基于本文提出的隧道内壁爆炸超压的简化模型和相应于隧道衬砌和周围土体而采取的 von-Mises 和 Mohr-Coulomb 等屈服准则,应用 Newmark 增量时程计算中的等效载荷法对各体系进行隧道内爆炸作用下的弹塑性动力响应分析。与使用 Lysmer粘滞边界法和修正的 Lysmer 粘滞边界法的结果比较,验证了本文方法的有效性。(2)针对地下爆炸波冲击下多层建筑和大跨屋盖结构的基底滑移隔震分析和连续梁桥的摩擦摆支座隔震分析而分别建立起各个隔震装置的力学模型,提出了以滑移接触面压力和相对滑移速度为自变量的各个修正连续摩擦力模型。这不仅消除了应用传统库仑摩擦力模型所带来的对啮合、滑移阶段及其过渡边界需时刻跟踪以及易造成较大累积误差等缺陷,还使摩擦力的确定过程大为简化。(3)应用本文提出的单元塑性区域确定方法,研究了隧道及其周围土体在隧道内爆炸发生时的塑性区域拓展规律;分析了自由场地表各点位移、速度及加速度的峰值变化趋势以及地下爆炸波沿地表传播的行波效应和衰减特征。至于地下爆炸波冲击下上述三类地表结构在同时考虑土-结构相互作用、各个滑移装置的独立工作以及地下爆炸波的行波效应等因素时(后两者主要针对大跨屋盖结构和连续梁桥而言)的复杂动力响应计算问题,应用本文的模型及求解方法均可自然、良好地加以解决。对连续梁桥来说,本文的相关模型及解法还自然考虑了凹形地表对地下爆炸波行波效应的影响以及该爆炸波遇凹形地表后的散射问题。(4)应用本文方法对地下爆炸波冲击下多层建筑和大跨屋盖结构在非隔震和基底滑移隔震两种情况下的动力响应进行了比较分析,揭示了摩擦系数和地基强度等参数对其隔震效果的影响规律;对地下爆炸波冲击下连续梁桥在分别设置钢性球铰支座、板式橡胶支座和摩擦摆支座等三种情形下的动力响应进行了比较分析,揭示了摩擦系数和地基强度等参数对摩擦摆支座隔震效果的影响规律。对大跨屋盖结构和连续梁桥还提出了“残余内力”问题,分析了影响其大小的一些因素。上述工作既为进一步的理论研究奠定了基础,也为具体工程实践提供了重要而有益的借鉴。更多还原

【Abstract】 A fierce explosion occurring in an underground tunnel of city usually causes severedamage to the tunnel lining, the surrounding soil and even some structures on the groundadjacent to the tunnel. In order to discover the laws for the dynamic responses ofdifferent types of structures to the underground explosion waves from the accident andthen to develop some shock absorber or isolator of those structures and evaluate theireffects, a systematical study on the dynamic responses and the sliding-isolation effects ofthe three types of structures, consisting of the multistory building, the long-spanroof-truss structure and the continuous-girder bridge, under the impact of theunderground explosion waves is performed in this dissertation, and the primaryinnovative work and achievements are as follows.(1) Some different kinds of numerical methods are introduced to establish variouscoupling models of systems, including the underground tunnel, semi-infinite soil and thethree types of structures whether their sliding isolation equipment is installed or not,using sub-structure theory. According to the proposed simplified model of overpressureon the tunnel wall and the von-Mises’ and the Mohr-Coulomb’s yielding principlescorresponding to the tunnel and the soil around respectively, the elaso-plastic dynamicresponses of various systems to the explosion inside the tunnel are numerically analyzedby means of the equivalent-load method in the Newmark increment calculation. Incomparison with the results of the Lysmer viscous boundary method and the modifiedLysmer viscous boundary method, the validity of the methods proposed in thedissertation is proved.(2) In respect of the sliding base-isolation analyses of the multistory building and thelong-span roof-truss structure and the friction pendulum isolation analyses of thecontinuous-girder bridge, the mechanical models of various isolation installations arebuilt, and a number of the modified continuous friction models with the compressiveforce of the sliding interface and the sliding velocity relative regarded as the independentvariables are proposed. This not only avoids some disadvantages of the traditionalCoulomb friction model, like tracing momentarily the phases of the meshing and thesliding and the boundaries between them and resulting easily in remarkable accumulatederrors, but also makes the process of determining the friction simplified greatly.(3) With a method suggested in the dissertation to determine the plastic region of element,the law of extending of the plastic region in the tunnel and the soil around on account ofthe explosion happening in the tunnel is investigated. In addition, the varying trends of<WP=5>the peak displacements, the peak velocities and the peak accelerations at the surfacepoints of the free-field are analyzed, and the travelling-wave effects and the attenuationcharacteristics of the underground explosion waves propagating along the earth’s surfaceare testified at the same time. As for the complicated computation about the dynamicresponses of the three types of structures to the underground explosion wavesconsidering the soil-structure interaction, the independent work of every sliding isolationinstallation and the traveling-wave effect of the blast waves all together (the last twofactors are mainly related to the long-span roof-truss structures and the continuous-girderbridge), the models and solutions offered in the dissertation can be used to naturally andbetter deal with it. For the continuous-girder bridge, the related models and solutions canalso naturally consider both the influence of the concave surface of the earth on thetraveling-wave effect of the blast waves and the scatter problem of the blast waves on theconcave surface.(4) Some comparative analyses on the dynamic responses of the multistory building andthe long-span roof-truss structure, considering no isolation and the sliding base-isolation,to the underground explosion waves are executed usi更多还原