本文選題：被動柔性防護網(wǎng)　切入點：防護性能　出處：《重慶交通大學(xué)》2014年碩士論文　論文類型：學(xué)位論文

【摘要】：被動柔性防護技術(shù)是一種輕型化的防護手段，常用于治理工程中的崩塌落石問題，以其防護能級高、防護效果好、安裝快捷、工程成本低等優(yōu)點在公路行業(yè)得到了大量推廣、運用。目前，被動防護系統(tǒng)的的研究成果主要集中在對崩塌及落（滾）石的運動軌跡、耗能特性、變形情況、沖擊力峰值等方面；對于柔性防護網(wǎng)防護性能的影響因素方面的研究分析還比較少，還有待一步研究。因此，本文對被動柔性防護網(wǎng)的防護性能影響因素進行研究，為以后的工程設(shè)計提供更多參考依據(jù)。 本研究主要采用有限元軟件ANSYS LS-DYNA建立的數(shù)值模型對公路邊坡被動柔性防護網(wǎng)的防護性能展開計算、研究。首先，通過查閱國內(nèi)外資料，整理總結(jié)了關(guān)于被動柔性防護網(wǎng)的工程應(yīng)用以及其防護性能的研究現(xiàn)狀；并介紹了柔性防護技術(shù)的防護原理及技術(shù)指標(biāo)，為后面建模提供了理論依據(jù)。然后，用過有限元軟件對RX-050被動柔性防護網(wǎng)進行建模，在建模過程中對錨桿、減壓環(huán)作用進行了一定的簡化。建立了網(wǎng)-繩系統(tǒng)局部數(shù)值分析模型，通過計算、分析可知其構(gòu)件能量分布符合被動柔性防護系統(tǒng)各構(gòu)件之間進行能量、荷載的逐級傳遞消減這一規(guī)律。同時，對支撐繩直徑為8mm與16mm數(shù)值模型的動力學(xué)情況進行比較、分析。最后，根據(jù)不同影響因素建立出不同的條件下的數(shù)值模型，分析了防護網(wǎng)的能量、網(wǎng)繩變形和網(wǎng)繩軸力在各種工況條件下的變化規(guī)律，得出不同影響因素與柔性防護網(wǎng)性能的關(guān)系。 論文的主要研究成果有：①落石防護系統(tǒng)在相同受力情況下，增大支撐繩的截面積可以增強對網(wǎng)的支撐加固作用，減小支撐繩構(gòu)件所受應(yīng)力。②落石速度對柔性防護網(wǎng)防護性能有著最直接的影響，，落石防護系統(tǒng)網(wǎng)繩吸能效率、網(wǎng)繩變形能力、網(wǎng)軸力最大值均隨著落石速度的增加而增大。③相同沖擊動能下，半徑越小的落石，越容易產(chǎn)生“子彈效應(yīng)”，使網(wǎng)發(fā)生局部破壞。④當(dāng)落石以尖點撞擊防護網(wǎng)時更容易發(fā)生網(wǎng)的局部破壞，撞擊區(qū)域面積減小更容易造成網(wǎng)的局部應(yīng)力集中。⑤防護網(wǎng)的防護高度一定時，增大鋼柱間距有利于提高被動防護系統(tǒng)構(gòu)件的抗沖擊能力。⑥在落石沖擊動能的作用下，菱形網(wǎng)防護網(wǎng)的防護性能隨著網(wǎng)孔規(guī)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.
【學(xué)位授予單位】：重慶交通大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：U417.1

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