【作者】 陈宪麦；

【导师】 陶夏新；

【作者基本信息】 中国地震局工程力学研究所 ， 防灾减灾工程及防护工程， 2003， 硕士

【摘要】 公路工程在我国国民经济中正在发挥越来越重要的作用。近十几年来，通车里程迅速增加，技术等级大幅度提高，公路桥梁和隧道建设取得显著成果。从国内外大量地震的震害中能够看到，现代公路工程仍然十分脆弱，在地震中容易遭受破坏，影响甚至中断交通，还会给震后救灾工作带来极大困难。公路工程的震害表明，挡土结构的地震破坏，往往是造成道路受损、桥梁破坏的主要原因之一。受各种条件限制，挡土墙的抗震验算，仍普遍采用拟静力法(以下简称静力法)。地震惯性力和地震土压力的确定方法，是目前挡土结构的抗震分析中有待深入研究改进的课题。我国现行《公路工程抗震设计规范》(JTJ 004-89)已使用十多年。在这期间，我国公路工程建设高速增长，科学技术有了长足发展，公路建设的规模大大超过此前。规范的部分内容已落后于时代、落后于地震工程科学技术的发展，不能很好的满足我国的公路工程的建设和发展。为此，迫切需要更新，采用更先进、成熟的理论和方法。结合规范JTJ 004—89的修编，本文在总结已有研究成果的基础上，主要研究了挡土墙和桥台地震惯性力沿高度分布的规律，粘性填土的地震土压力计算和计算公式的简化，以及在公路工程抗震设计规范中将挡土墙和桥台的抗震设计归入一章的问题，具体包括如下5项工作。 1．综合评述国内外公路工程抗震设计规范中地震作用计算方法以及地震土压力计算方法的演进历史及现状，详细分析我国现行公路工程抗震设计规范中挡土墙和桥台的抗震验算方法，指出存在的问题和解决这些问题的必要性。 2．选用针对地震烈度6、7、8、9合成的总共18条地震动时程，选取具有代表性的6个不同高度的挡土墙以及2个不同高度的桥台模型，利用波动有限元法既有程序分析地震反应，研究水平地震加速度沿高度的分布规律。数值结果显示，重力式挡土结构刚度很大，地震加速度反应在水平方向差异很小，可看作是同步的，可取中心线上各点最大加速度来描述静力法中地震作用沿高度的变化规律。在沿墙高度方向，加速度分布不是呈直线变化，比较复杂，总的变化趋势大体一致。从挡墙底部开始，最大地震加速度并不马上随高度的增加而增大，直至高度达到挡墙总高度的1／2—2／3处才开始比较迅速的增加，至项部达到最大值，约为底部的1.1-2.0倍。高挡墙(高度25米)自振周期长，对近处小震放大不明显，除此以外，中国地震局工程力学研究所硕士学位论文顶部放大都在14倍以上。放大倍数，随挡墙总高度的增大，呈渐增的趋势，只有个别的超过1名倍(大于1.9的占2.1%，大于1.8的占35%)。根据这些规律性的认识，本文建议了两种挡土结构水平地震作用沿相对墙高(高度与挡墙总高度的比)分布系数，一种折线型、一种曲线型，最大值均取1 .8。 3.规范JTJ 00牛se-89规定当挡土墙高度大于12米时才考虑加速度沿墙高的放大效应，可能不够安全。本文计算结果表明，高度高7米、9米的挡土墙和高度6米、8米的扩大基础桥台的地震加速度反应在顶部也会有约1，5一1.6倍的放大。为了安全，本文建议改以6米为界限，墙高小于6米的可以不考虑地震惯性力沿墙高的增大。 4.基于广义库仑基本理论的最近研究成果叫’]，整理、推导了粘性填土地震主动土压力和被动土压力的计算表达式，得出了考虑填土为粘性土、填土表面作用均布荷载、填土表面有一定坡度的地震土压力解析解。导出的计算公式很复杂，应用到实际工程、采纳到规范中，仍有一定难度。在分析粘性土地震土压力对计算公式中各因素敏感性的基础上，采用厂十。型思路，部分吸收M一O法的优点，借鉴Seed一Whi加an对M一O公式简化思想，本文提出了两种简易工程计算式。结合具体算例，将第一种简化算式与国内外多种计算公式的结果进行了比较，将第二种简化算式与现行水运工程抗震设计规范的粘性土地震土压力计算式的结果进行了对比，说明了本文建议公式的适用性和工程应用价值。此外，还简单地讨论了本文方法在一些复杂问题地震土压力计算中的应用。 5.现行公路工程抗震设计规范中将挡土墙和桥台的验算分放在两章考虑，分别按各自的公式计算，造成一定的不方便。本文从挡土结构承受地震作用和地震土压力两个方面分析，强调了这两类结构验算的共性，将挡土墙和桥台的抗震验算统一了起来，并建议在规范修编中列入一章。 最后，对本文工作进行了总结，并提出了有待今后继续研究的三个问题。更多还原

【Abstract】 Highway system plays a more and more important role in the national economy. In the past ten odd years, a great progress has been made in highway construction. The total length of road, the length of good quality highway, number of the bridges and tunnels are all increased and increasing remarkably. Seismic damage of highway system caused in strong earthquake worldwide indicated that modern Highway system is still vulnerable, it may be damaged extensively and slow down so much as shut down the local traffic, which always makes big troubles for rescue in a past earthquake situation. The earthquake damage of Highway system shows that the failure of retaining structures is sometimes one of the main causes of road damage and bridge collapse. The pseudo-static method (static method in brief) is now currently adopted in seismic analysis of retaining structures for some well known limitation. The study on seismic inertia and seismic soil pressure is a significant task to be deeply treated with and improved in the static analysis of retaining structures. The currently used Chinese Earthquake Resistant Design Code for Highway Construction (JTJ 004-89) was issued a dozen years ago. During this period. Highway construction increased very fast in China and the scale was much larger than ever before, while the technology was developed quite great. Some contents of the code now have dropped behind the progress of science and technology and the development of the epoch and can not meet the requirement of the development of highway construction any longer. Therefore the code needs to be updated by some more advanced and mature theories and approaches. On basis of a review of the recent achievements, the distribution of the lateral seismic inertia force along the height of retaining wall and/or bridge abutment, and the calculation of the seismic soil pressure of cohesive backfill are treated with in this paper, for the revision of Chinese Earthquake Resistant Design Code for Highway Construction, and a suggestion to combine seismic design of retaining wall and of bridge abutment together into one chapter from the past in two chapters in the previous version is also worked out. The main contents are summarized as follows:1. The evolution, state of the art and the developing trend of the lateralseismic inertia force calculation for retaining wall and/or bridge abutment and the calculation of the seismic cohesive backfill soil pressure are reviewed. The approaches of seismic analysis of retaining walls and bridge abutments in the current Highway codes of China are studied in detail and the shortcomings in the analysis procedure and the necessity of further improvements to them are pointed out.2. Total 18 simulated acceleration time histories for Intensity 6, 7, 8 and 9 are adopted as inputs, 6 typical retaining walls heights and 2 bridge abutments with difference are selected as the structural models of soil-structure system, the seismic responses of the system and the horizontal variation of the maximum response accelerations at different height levels are analyzed by means of a wave propagation finite element program. The numerical results show that the horizontal variation of response acceleration of gravity retaining wall is quite small since its lateral rigidity is large enough, the response at a given height level can be considered as the same, the maximum accelerations at different heights on the central vertical line can describe the distribution of earthquake load along the wall height in static analysis very well. The acceleration changes along the height direction nonlinearly with a little bit complicated pattern, and the changing patterns, in general, are similar. The acceleration does not increase immediately after the wall height is getting taller from the bottom of the retaining wall, and it starts to increase rapidly with the height level at a height of half to two thirds of the total wall height. It gets a maximum amplification value of 1.1 to 2.0 at the top of the wall. The ratios between accel更多还原