水环境下大跨度上承式拱桥的静、动力特性分析

发布时间：2018-11-16 20:13

【摘要】：近年来,随着高速公路的发展,铁路的提速,对道路的线形要求日益提高,沿线不免跨越深沟峡谷。由于峡谷的地形条件,以上承式拱桥方案较为合理。然而,对于水资源丰富的地区而言,峡谷又是水利工程建设多选地形。从实现经济效益的角度而言,线路爬坡高度不宜太高,设计标高的降低导致拱圈多半会为库水所淹。虽然水体与空气同属于流体,但在具体的某些特性上仍有不同,本论文基于此对库区大跨度上承式拱桥展开分析研究:首先,针对库区大跨度上承式拱桥有别于其他拱桥的环境特征,确定该类拱桥在动静力分析时有别于其他拱桥的主要影响要素。大跨度上承式拱桥水下部分结构会受到水体的影响。在正常水环境下,流水对结构的作用主要在于侧向流水压力和竖向水浮力。在地震作用下,结构会产生变形、振动,同时导致水体振动,使水体通过动水压力的形式反作用于结构,从而在结构与水体之间形成作用与反作用并贯穿地震作用始终,因此流固耦合是地震作用下的主要影响因素。其次,对流体的基本特性进行了研究,得到了水下拱圈部分的流水压力、水浮力计算公式。对现有流固耦合的计算理论进行了研究,探寻适合水下拱圈结构的流固耦合计算方法。再次,对拱结构的有限元理论进行了研究探讨。虽然曲梁单元更适用于解拱的荷载效应、自由振动和强迫振动,但由于其复杂性,工程上的有限元仍更多的采用以直代曲的方法来求解拱结构效应。最后,根据工程实例,建立大跨度上承式拱桥的空间有限元模型,考虑静力分析时的两个主要影响因素—流水压力和水浮力的作用,分析两个主要影响因素对拱圈内力的影响程度及影响规律,探讨流水速度影响下,能否忽略流水压力的影响,将库水视为静水,探讨在低烈度地震设防区,静水环境下拱圈可能被淹没的高度;研究考虑流固耦合作用后,拱圈淹没深度对拱桥自振特性的影响规律以及此时地震作用下,拱圈淹没深度对拱圈内力影响程度及影响规律,探讨在高烈度地震设防区,拱圈所能承受的淹没高度。
[Abstract]:In recent years, with the development of freeway and the increase of railway speed, the demand for road alignment is increasing day by day, so it is inevitable to cross deep gully canyons along the line. Because of the terrain condition of the canyon, the scheme of the above arch bridge is reasonable. However, for water rich areas, canyons are a multi-choice terrain for water conservancy projects. From the point of view of realizing economic benefit, the climbing height of the line should not be too high, and the decrease of the design elevation will cause the arch ring to be flooded by the reservoir water. Although the water and air are both fluid, there are still some differences in some specific characteristics. Based on this, this paper carries out an analysis and research on the large-span arch bridge in the reservoir area: first of all, In view of the environmental characteristics of long-span overbearing arch bridges different from other arch bridges in the reservoir area, it is determined that the main influencing factors of this kind of arch bridges are different from other arch bridges in dynamic and dynamic analysis. The underwater structure of long span overbearing arch bridge will be affected by water. In normal water environment, the effect of flowing water on the structure mainly lies in the lateral flow pressure and vertical water buoyancy. Under the action of earthquake, the structure will deform and vibrate, and at the same time, it will cause the water body to vibrate, so that the water body will react on the structure through the form of dynamic water pressure, thus forming the action and reaction between the structure and the water body and running through the earthquake action all the time. Therefore, fluid-solid coupling is the main influencing factor under earthquake. Secondly, the basic characteristics of the fluid are studied, and the calculation formulas of the flowing water pressure and the water buoyancy of the underwater arch ring are obtained. In this paper, the calculation theory of fluid-solid coupling is studied, and the fluid-structure coupling calculation method suitable for underwater arch ring structure is explored. Thirdly, the finite element theory of arch structure is studied. Although the curved beam element is more suitable for the load effect, free vibration and forced vibration of the arch, but because of its complexity, the engineering finite element method is more often used to solve the arch structure effect. Finally, according to the engineering example, the spatial finite element model of long-span overbearing arch bridge is established, and two main influencing factors in static analysis are considered, which are the effect of flowing water pressure and water buoyancy. This paper analyzes the influence degree and law of two main influencing factors on the internal force of arch ring, discusses whether the influence of flowing water pressure can be ignored under the influence of flowing water velocity, regards reservoir water as static water, and probes into the fortification area of low intensity earthquake. The height at which the arch can be submerged in a still water environment; After considering the fluid-solid coupling, the influence of the submergence depth of the arch ring on the natural vibration characteristics of the arch bridge and the degree and law of the influence of the submergence depth of the arch ring on the internal force of the arch ring under the action of the earthquake at this time are studied, and the fortification area of the high intensity earthquake is discussed. The height at which the arch can withstand the inundation.
【学位授予单位】：长沙理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U441;U448.22

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