【摘要】：在西部地區(qū),公路橋梁和房屋建筑大多依山而建,再加之西部地區(qū)處在地震帶區(qū)域,地震帶來的地質(zhì)災(zāi)害不同程度的威脅著已建和在建工程。特別是5.12地震之后,流域沿線兩側(cè)山體出現(xiàn)松動(dòng),由于多種原因?qū)е碌谋浪涫闆r越發(fā)頻繁,山區(qū)公路、隧道棚洞、橋梁遭到撞擊損壞的事故日益增多,山區(qū)落石危害的問題就越來越突出。國內(nèi)外關(guān)于落石撞擊橋墩的研究較多,關(guān)于橋面板的則研究較少,板類構(gòu)件在低速?zèng)_擊作用下有明顯的整體響應(yīng),和前者有很大不同,值得深入研究。為此,本文通過室內(nèi)試驗(yàn)、數(shù)值仿真和理論推導(dǎo)來研究和驗(yàn)證上述問題。具體內(nèi)容和結(jié)論如下:(1)混凝土板低速?zèng)_擊試驗(yàn)通過室內(nèi)小尺寸混凝土板模型試驗(yàn),研究在低速?zèng)_擊荷載作用下,混凝土板的破壞過程、開裂形式及沖擊力影響參數(shù)。試驗(yàn)可知:混凝土板的碰撞過程比落石撞擊橋墩碰撞時(shí)間長(zhǎng),原因是碰撞過程包含了板的整體變形和變形恢復(fù)過程;沖擊力的大小與板厚、沖擊速度和混凝土強(qiáng)度都有一定關(guān)系,其中速度和板厚影響更大,混凝土強(qiáng)度對(duì)靶板破壞形態(tài)有一定影響。(2)針對(duì)低速?zèng)_擊的數(shù)值模擬參數(shù)優(yōu)化利用LS-Dyna建立有限元模型,模擬低速大質(zhì)量體撞擊混凝土板過程,結(jié)合模型試驗(yàn)數(shù)據(jù)優(yōu)化數(shù)值模擬設(shè)置參數(shù),使模擬結(jié)果更趨近真實(shí)情況。(3)低速?zèng)_擊作用下混凝土板破壞機(jī)理研究基于室內(nèi)模型試驗(yàn)和數(shù)值模擬的破壞效應(yīng)和破壞特征,結(jié)合塑性板理論可知:混凝土板在大質(zhì)量低速度沖擊作用下大多出現(xiàn)彎曲破壞,但隨著速度增大,混凝土板中心局部沖切破壞特征會(huì)愈加明顯。(4)落石撞擊混凝土板的沖擊力計(jì)算方法推導(dǎo)基于在室內(nèi)模型試驗(yàn)和數(shù)值模擬結(jié)果,在前人研究的基礎(chǔ)上推導(dǎo)考慮結(jié)構(gòu)整體變形的落石沖擊力計(jì)算方法。該方法得到的計(jì)算結(jié)果與試驗(yàn)結(jié)果和有限元解均相差不大,偏差在30%以內(nèi),本文計(jì)算方法合理。
[Abstract]:In the western region, most of the highway bridges and buildings are built according to the mountains, and the western region is located in the seismic zone, the geological hazards caused by the earthquake threaten the construction of the existing construction projects to varying degrees. In particular, after the May 12 earthquake, the mountains along the river basin were loosened, and the collapse and fall of rocks due to various reasons became more and more frequent. The accidents of mountain roads, tunnels and bridges being damaged by impact were increasing day by day. The problem of falling rocks in mountain areas is becoming more and more serious. At home and abroad, there are more researches on falling stone impact pier and less on bridge deck slab. The whole response of slab members under low speed impact is obvious, which is very different from the former, so it is worthy of further study. Therefore, the above problems are studied and verified by laboratory test, numerical simulation and theoretical derivation. The main contents and conclusions are as follows: (1) the failure process, cracking form and impact force parameters of concrete slabs under low speed impact load are studied through the model tests of small size concrete slabs in laboratory. Experimental results show that the impact process of concrete slab is longer than that of stone fall impact bridge pier, because the impact process includes the whole deformation and deformation recovery process of the slab, the impact force and the thickness of the slab. There is a certain relationship between impact velocity and concrete strength, in which velocity and slab thickness have more influence, and concrete strength has certain influence on the failure pattern of target slabs. (2) the finite element model is established by using LS-Dyna to optimize the numerical simulation parameters of low velocity impact. In order to simulate the impact process of low speed and large mass body against concrete slab, the parameters of numerical simulation are optimized with model test data. The simulation results are more realistic. (3) the failure mechanism of concrete slabs under low speed impact is studied based on the failure effect and failure characteristics of indoor model test and numerical simulation. Combined with the theory of plastic slabs, it can be seen that most of the concrete slabs under the action of large mass and low velocity impact appear bending failure, but with the increase of velocity, The characteristics of local punching failure in the center of concrete slabs will become more obvious. (4) the calculation method of impact force of rockfall impact concrete slabs is derived based on the results of indoor model tests and numerical simulation. On the basis of previous studies, the calculation method of rock drop impact force considering the whole deformation of structure is deduced. The calculated results obtained by this method are not different from the experimental results and the finite element solutions, and the deviation is less than 30%. The calculation method in this paper is reasonable.
【學(xué)位授予單位】：西南科技大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：U446

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本文編號(hào)：2149196