流冰与桥墩的相互作用

发布时间：2018-02-14 06:09

本文关键词： 流冰桥墩冰温强度相互作用防撞措施　出处：《东北林业大学》2014年博士论文　论文类型：学位论文

【摘要】：在我国境内,北纬35°以北的湖泊、水库、河流等水域均会出现冰冻现象,在冬春季节容易发生凌汛现象,尤其是青藏高原上江河、嫩江上游、黄河下游河段、黑龙江上游河段、松花江依兰以下河段、黄河内蒙古河段等水域春季凌汛现象更为严重,冰凌经常造成河道拥堵,对防洪、交通、给排水、水利水电工程等运营施工产生非常不利的影响。因此,深入研究流冰与桥墩的相互作用,提出防冰撞措施,预防和根治冰灾害,确保人民生命和财产安全,具有非常重要的现实意义。针对我国最易发生流冰凌汛的江河,本论文对黑龙江流域、内蒙东北部地区、黄河中上游等进行了桥梁安全性及灾害影响调研,并分析了我国江河冰情的形成及演变过程。选定4处典型试验河段,建立了流冰期河冰温度试验场,并对其进行了长时间的温度观测。选定5处典型试验河段,进行河冰力学性能试验；根据试验结果,将温度、应变速率与河冰强度、弹性模量联系起来,并建立起它们之间的关系,提出考虑冰温、应变速率等因素后计算河冰强度标准值的方法。同时,运用LS-DYNA显式动力分析软件,以非线性有限元分析理论和接触-碰撞理论为依据,对流冰撞击桥墩过程进行仿真分析,建立分析计算模型,探讨了冰排特性和桥墩破冰体形状对流冰撞击力的影响。具体工作如下： (1)针对流冰期河冰温度场,研究各试验河段流冰期冰温沿冰厚的分布规律。以通用全局优化法和准牛顿法为依据,运用lstOpt软件,建立黑龙江省三个区域的冰温、水温、气温三者关系的数值模型。 (2)结合河冰力学性能试验,提出冰温、应变速率对抗压强度和压缩弹性模量的影响及对弯曲强度和抗弯弹性模量的影响,温度和应变速率呈相近的变化规律。 (3)在相同温度和加载速率条件下,得出黑龙江省各区域的冰的抗压强度均比抗弯强度大,在相同加载速率作用下,压缩弹性模量约为弯曲弹性模量的50%,单轴压缩强度约为抗弯强度的1.7倍的结论。 (4)通过对影响撞击力仿真计算的建模因素研究,分析接触类型及接触算法的影响。计算得出流冰撞击力随着冰排强度、弹性模量、冰排厚度的增加而呈增大的趋势。 (5)提出冰压力标准值的计算方法,冰强度的标准值根据历年流冰时最低的加权平均冰温和最大的冰流速计算确定,也可以根据历年流冰时最低气温、水温和最大冰流速计算来确定。这种确定方法符合桥位河段现场的实际情况,从而大大提高了计算的精准度。 (6)研究流冰撞击破坏的机理及破冰体形状、倾角对流冰撞击力的影响。提出不同桥墩模式所设置的不同尖角和竖向前棱倾角的取值范围,提升防撞效果。 (7)分析桥墩四种破坏形式,提出桥墩防冰撞设计原则,制定可经济、实用的防撞措施,有效地确保桥墩免受严重流冰的毁坏。流冰与桥墩相互作用的研究成果为下步防冰撞技术措施的研究奠定基础,并为桥墩防冰撞设计提供有效的参考意见。
[Abstract]:In our country, north latitude 35 degrees north of the lake, reservoir, river water will be frozen, prone to the phenomenon of ice in the winter season, especially in the Qinghai Tibet Plateau on the river, the upper reaches of the Nenjiang River, the Yellow River River, Heilongjiang River, Songhua River and Yilan in the lower reaches of the the Yellow River River, Inner Mongolia and other waters in spring flood phenomenon serious, often caused by river ice jams, for flood control, transportation, water supply and drainage, water conservancy and hydropower engineering construction operations have a very negative impact. Therefore, research on the interaction of ice and pier, the anti ice bump measures, prevention and cure of ice disaster, to ensure the safety of people's lives and property, has very important practical significance.
In our country the most prone to ice flood river, the Heilongjiang River Basin, Northeastern Inner Mongolia, the Yellow River and other upstream of the bridge safety and disaster affected research, and analyzes the formation of China's rivers of ice and evolution. Selected 4 typical test section, a period of river ice ice temperature the test field, and has carried on the observation of temperature long time. Selected 5 typical test section, test of river ice mechanical properties; according to the test results, the temperature, strain rate and river ice strength, contact elastic modulus, and establish the relationship between them, proposed method of river ice temperature. The ice strength standard value calculation factor and strain rate. At the same time, using LS-DYNA explicit dynamic analysis software, based on the nonlinear finite element analysis theory and contact impact theory, convection ice pier collision simulation analysis process, establish Analysis and calculation model, discusses the influence of ice and ice pier body shape characteristics of convective impact force. The specific work is as follows:
(1) the river ice temperature field of ice period, ice thickness distribution along the river ice ice temperature test period. The general global optimization method and quasi Newton method based on the use of lstOpt software, the establishment of ice temperature, the three regions of Heilongjiang Province, the water temperature, the numerical model of the temperature of the relationship between the three.
(2) combined with the mechanical performance test of river ice, the influence of ice temperature and strain rate on compressive strength and compressive elastic modulus and the influence of flexural strength and bending modulus of elasticity are put forward.
(3) under the same temperature and loading rate, it is concluded that the compressive strength of each area in Heilongjiang is greater than that of flexural strength. Under the same loading rate, the compressive elastic modulus is about 50% of the flexural modulus, and the uniaxial compressive strength is 1.7 times the bending strength.
(4) through the research of modeling calculation on the influence factors of impact force simulation, influence of contact type and contact algorithm. The calculated ice impact force with ice strength, elastic modulus, and the increase of ice thickness increases.
(5) proposed a method to calculate the standard value of the pressure of ice, ice strength standard value calculated and determined according to the weighted average of the lowest over the ice ice temperature and maximum ice velocity, ice can also be based on the calendar year when the minimum temperature, maximum temperature and ice velocity calculation to determine. This determination method in accordance with the actual situation of the bridge site reach the scene, which greatly improves the calculation accuracy.
(6) the mechanism and ice shape research of ice collision damage, influence of inclination of convection impact force. The range of proposed different pier mode set by different angle and vertical angle of the forward edge, enhance the anti collision effect.
(7) analysis of pier four failure modes, the anti ice pier hit design principles, develop economy, practical anti-collision measures, effectively ensure the destruction of the pier from serious ice.
The results lay the foundation of ice and pier interaction for the next step into the anti icing technical measures, and provide effective reference for design of anti ice pier hit.

【学位授予单位】：东北林业大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：U443.22;U442.3

【参考文献】