桥隧相连落石防护新型结构设计技术研究

发布时间：2018-08-07 15:53

【摘要】：近年,我国铁路建设快速发展,新建线路不断向地质复杂困难的山区延伸。高标准的山区铁路经常采用桥隧相接的形式通过大高差地貌单元,桥隧相连洞口上方落石给铁路运营安全带来很大安全风险。目前,对于桥隧相接落石防护结构的动力响应研究还不多,相应的工程设计还缺少基础性技术支撑。因此,研究隧道洞口桥隧相连落石防护复合结构的合理结构形式、以及主要外部动力作用下的结构动力响应具有重要的理论和实际意义。本研究首先对国内外隧道洞口落石灾害、防护措施、防护结构与桥梁的连接方式进行案例调查,明确落石冲击作用的主要影响因素,对落石防护结构的形式进行探讨,提出翼缘板纵梁式矩形框架型和拱墙型棚洞作为桥隧相接落石防护复合结构的两种基本结构形式进行研究;然后以张怀客专邓家坡隧道进口桥隧相连为研究对象,通过理论分析确定落石冲击荷载的最不利工况,采用三维动力有限元数值模拟的技术手段,研究不同能级的落石冲击荷载作用下落石防护复合结构的动力响应,针对各种落石能级验算桥梁翼缘板承载力,并提出相应的工程对策;最后分别对地震和侧向风荷载作用下桥隧相接落石防护复合结构的动力响应进行初步分析计算,探讨地震和侧向风荷载的影响。主要研究成果如下:(1)通过文献调查,分析了桥隧相接落石防护的主要工程对策,明确了落石防护能量的设计等级,提出了两种落石防护复合结构的结构形式(翼缘板纵梁式矩形框架型和拱墙型棚洞)。(2)利用三维动力有限元技术,对两种防护复合结构进行了落石冲击数值模拟。分析了不同缓冲层在减少落石冲击力和增加冲击距离方面的作用,明确了落石冲击位置对棚洞结构受力的影响,讨论了落石冲击对棚洞作用的最不利工况,得到了各种能级作用下棚洞的落石冲击力系数。(3)根据落石冲击数值模拟的结果,明确了落石冲击通过棚洞纵梁对桥梁翼缘板产生附加冲击荷载,得到了棚洞立柱附加轴力冲击系数,提出了翼缘板加固方案并验算了安全性。(4)利用三维动力有限元技术,分别对侧向风荷载和地震作用进行了初步分析计算。明确了侧向十级风荷载对棚洞复合结构以及桥梁的作用比较小。地震作用下棚洞复合结构对桥墩的断面力影响较大,需要进一步研究。
[Abstract]:In recent years, with the rapid development of railway construction in China, the newly-built railway lines continue to extend to mountainous areas with complicated geological conditions. The high standard mountain railway often uses the bridge and tunnel connection form through the big height difference geomorphology unit, the bridge and tunnel connects the tunnel mouth to fall the stone to bring the very big safety risk to the railway operation safety. At present, there is not much research on the dynamic response of the bridge and tunnel rock fall protection structure, and the corresponding engineering design is still lack of basic technical support. Therefore, it is of great theoretical and practical significance to study the reasonable structure form of the composite structure with rock fall protection at the tunnel entrance, and the dynamic response of the structure under the main external dynamic action. In this study, first of all, a case investigation was carried out on the rock fall disaster at the tunnel entrance, the protective measures, the connection between the protection structure and the bridge, and the main influencing factors of the rock fall impact were identified, and the form of the stone fall protection structure was discussed. The flange plate longitudinal beam type rectangular frame type and arch wall type shed tunnel are proposed as the two basic structure forms of the composite structure of stone fall protection, and then the entrance bridge and tunnel of Dengjiapo Tunnel of Zhanghuai Special College is taken as the research object. Through theoretical analysis, the most unfavorable condition of falling stone impact load is determined. The dynamic response of falling stone protection composite structure with different energy levels under falling stone impact load is studied by means of 3D dynamic finite element numerical simulation. The bearing capacity of flange plate of bridge is checked according to various falling rock levels and corresponding engineering countermeasures are put forward. Finally, the dynamic response of the composite structure of bridge and tunnel falling stone under earthquake and lateral wind load is analyzed and calculated. The influence of earthquake and lateral wind load is discussed. The main research results are as follows: (1) through the literature investigation, the paper analyzes the main engineering countermeasures of the bridge and tunnel rock fall protection, and clarifies the design grade of the falling stone protection energy. In this paper, two kinds of composite structures (flange plate longitudinal beam rectangular frame type and arch wall shed tunnel). (2) are proposed to simulate the falling stone impact of the two composite structures by using three-dimensional dynamic finite element technique. The effects of different buffer layers on reducing the impact force and increasing the impact distance are analyzed. The influence of the impact position on the stress of the shed tunnel structure is clarified, and the most unfavorable working condition of the stone falling impact on the shed tunnel is discussed. The rock drop impact force coefficients of the shed tunnel under various energy levels are obtained. (3) according to the numerical simulation results of the falling stone impact, the additional impact load on the flange plate of the bridge caused by the falling stone impact through the longitudinal beam of the shed tunnel is determined. The impact coefficient of additional axial force is obtained, and the strengthening scheme of flange plate is put forward and the safety is checked. (4) the lateral wind load and seismic action are preliminarily analyzed and calculated by using three-dimensional dynamic finite element method. It is clear that the lateral ten-step wind load has little effect on the composite structure and bridge. The composite structure of shed-hole has a great influence on the cross-section force of bridge pier under earthquake, which needs further study.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U443.8;U453.8

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