公路边坡被动柔性防护网性能分析研究

发布时间：2018-03-14 17:20

本文选题：被动柔性防护网　切入点：防护性能　出处：《重庆交通大学》2014年硕士论文　论文类型：学位论文

【摘要】：被动柔性防护技术是一种轻型化的防护手段，常用于治理工程中的崩塌落石问题，以其防护能级高、防护效果好、安装快捷、工程成本低等优点在公路行业得到了大量推广、运用。目前，被动防护系统的的研究成果主要集中在对崩塌及落（滚）石的运动轨迹、耗能特性、变形情况、冲击力峰值等方面；对于柔性防护网防护性能的影响因素方面的研究分析还比较少，还有待一步研究。因此，本文对被动柔性防护网的防护性能影响因素进行研究，为以后的工程设计提供更多参考依据。本研究主要采用有限元软件ANSYS LS-DYNA建立的数值模型对公路边坡被动柔性防护网的防护性能展开计算、研究。首先，通过查阅国内外资料，整理总结了关于被动柔性防护网的工程应用以及其防护性能的研究现状；并介绍了柔性防护技术的防护原理及技术指标，为后面建模提供了理论依据。然后，用过有限元软件对RX-050被动柔性防护网进行建模，在建模过程中对锚杆、减压环作用进行了一定的简化。建立了网-绳系统局部数值分析模型，通过计算、分析可知其构件能量分布符合被动柔性防护系统各构件之间进行能量、荷载的逐级传递消减这一规律。同时，对支撑绳直径为8mm与16mm数值模型的动力学情况进行比较、分析。最后，根据不同影响因素建立出不同的条件下的数值模型，分析了防护网的能量、网绳变形和网绳轴力在各种工况条件下的变化规律，得出不同影响因素与柔性防护网性能的关系。论文的主要研究成果有：①落石防护系统在相同受力情况下，增大支撑绳的截面积可以增强对网的支撑加固作用，减小支撑绳构件所受应力。②落石速度对柔性防护网防护性能有着最直接的影响，，落石防护系统网绳吸能效率、网绳变形能力、网轴力最大值均随着落石速度的增加而增大。③相同冲击动能下，半径越小的落石，越容易产生“子弹效应”，使网发生局部破坏。④当落石以尖点撞击防护网时更容易发生网的局部破坏，撞击区域面积减小更容易造成网的局部应力集中。⑤防护网的防护高度一定时，增大钢柱间距有利于提高被动防护系统构件的抗冲击能力。⑥在落石冲击动能的作用下，菱形网防护网的防护性能随着网孔规格的增大而降低。
[Abstract]:Passive flexible protection technology is a light protection method, which is often used to control collapse and falling stone in engineering. It has been widely used in highway industry because of its advantages of high protection level, good protective effect, quick installation, low engineering cost, and so on. Application. At present, the research results of passive protection system mainly focus on the movement track, energy dissipation characteristics, deformation situation, peak impact force and so on of collapsing and falling (rolling) stone. The research and analysis of the factors affecting the protective performance of flexible protective nets are still few, and need to be further studied. Therefore, this paper studies the factors affecting the protective performance of passive flexible protective nets. To provide more reference basis for future engineering design. In this study, the numerical model established by the finite element software ANSYS LS-DYNA is used to calculate the protective performance of the passive flexible protective net of highway slope. This paper summarizes the engineering application of passive flexible protective net and the research status of its protective performance, and introduces the protection principle and technical index of the flexible protection technology, which provides the theoretical basis for the modeling of the passive flexible protective net. The RX-050 passive flexible protective net is modeled by the finite element software. In the process of modeling, the action of anchor rod and decompression ring is simplified. The local numerical analysis model of net-rope system is established, and the local numerical analysis model of the net-rope system is established. The analysis shows that the energy distribution of the components accords with the law of the energy between the components of the passive flexible protection system, and the gradual transfer and reduction of the load. At the same time, the dynamic conditions of the numerical model with the diameter of 8 mm and 16 mm of the supporting rope are compared. Finally, according to the different influence factors, the numerical model under different conditions is established, and the variation law of the energy, the deformation of the mesh rope and the axial force of the mesh rope under various working conditions are analyzed. The relationship between different factors and the performance of flexible protective net is obtained. The main research results of this paper are as follows: in the case of the same force, increasing the cross section area of the support rope can enhance the support reinforcement function of the net. Reducing the stress .2 falling velocity of the supporting rope member has the most direct influence on the protective performance of the flexible protective net, such as the energy absorption efficiency and the deformation ability of the wire rope in the stone falling protection system. The maximum value of net axial force increases with the increase of falling velocity. 3. Under the same impact kinetic energy, the smaller the radius is, the smaller the falling stone is. The easier it is to produce a "bullet effect", the more likely it is that the local damage of the net will occur when the falling stone hits the protective net at the tip of the net. When the impact area is reduced, it is easier to cause the local stress concentration of the net. 5. When the protective height of the protective net is constant, increasing the steel column spacing is beneficial to the improvement of the impact resistance of the passive protective system members. 6. Under the action of the impact kinetic energy of the falling rock, The protective performance of rhombus mesh decreases with the increase of mesh size.
【学位授予单位】：重庆交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U417.1

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