洪水環(huán)境下群樁基礎(chǔ)橋梁易損性分析與評估
發(fā)布時間：2018-08-05 15:53
【摘要】：橋梁作為交通生命線系統(tǒng)中的重要樞紐,在社會日常生活中起著至關(guān)重要的作用。對于跨越河流的橋梁,洪水是造成橋梁倒塌破壞的主因之一。洪水出現(xiàn)的頻率遠(yuǎn)高于地震,通常會帶來大規(guī)模的河流沖刷,從而引起劇烈的河床變化。盡管沖刷并不能對橋梁結(jié)構(gòu)形成直接的作用荷載,但它卻對橋梁的安全構(gòu)成了潛在威脅,將使橋梁在遭遇洪水、泥石流、地震等災(zāi)害下更易于損毀。因此,洪水環(huán)境下橋梁結(jié)構(gòu)的安全性研究是十分有必要的。易損性分析作為一種評估結(jié)構(gòu)安全性能的方法,廣泛應(yīng)用在結(jié)構(gòu)的抗震分析上,取得了豐富的成果,然而,將該分析手段應(yīng)用在洪水環(huán)境下橋梁的易損性分析與評估卻鮮有引起關(guān)注。因此,本文將嘗試將易損性分析用于評價橋梁在洪水環(huán)境下的安全性,針對洪水環(huán)境下典型群樁基礎(chǔ)橋梁的易損性分析與評估進行初步探索。本文首先回顧了國內(nèi)外學(xué)者在洪水災(zāi)害、沖刷以及易損性相關(guān)領(lǐng)域的研究現(xiàn)狀,接著敘述了易損性分析的基本理論和結(jié)構(gòu)損傷指標(biāo)的選取,提出了適用于橋梁抗洪性能研究的改進的混合易損性分析方法。以臺灣雙圓大橋為工程實例,借助Opensees有限元分析平臺建立了其下部結(jié)構(gòu)計算模型進行展開討論分析。文中第三章重點介紹了Opensees中的單元算法、非線性有限元分析理論以及雙圓大橋計算模型建立過程中的關(guān)鍵參數(shù)和需要注意的問題,包括樁工作用的處理、群樁效應(yīng)的簡化以及洪水荷載的施加等。在第四章中引入了洪水位高度和樁基沖刷深度的不確定性,運用隨機pushover分析方法,結(jié)合多變量隨機函數(shù)統(tǒng)計矩的點估計法求得了結(jié)構(gòu)在不同洪水位高度、不同沖刷深度下的抗洪能力概率分布情況。第五章則考慮了洪水位高度、沖刷深度以及洪水荷載的不確定性,運用有限元可靠度分析方法中的一次二階矩法(FORM)得到了 96種情況下的結(jié)構(gòu)抗洪需求概率分布。第六章結(jié)合前兩章的計算結(jié)果運用本文第二章提出的改進的混合易損性分析方法擬合并繪制了四種洪水位,三種洪水流速共12種情況下的易損性曲線,并以此評估該橋的安全性能,分析結(jié)果可作為決策的重要參考依據(jù)。本文得到的主要結(jié)論有:1)本文的計算結(jié)果與2009年臺灣雙圓大橋遭洪水沖毀的事故案例相吻合,也表明將易損性的分析思路用于結(jié)構(gòu)的抗洪安全性能評估是可行的,并能根據(jù)具體的研究對象給出定性的判斷和定量的參數(shù)分析,計算結(jié)果可作為決策參考依據(jù),具有一定的工程意義。2)同一洪水流速不同洪水位高度的易損性曲線具有相近的統(tǒng)計參數(shù),表現(xiàn)出相似的規(guī)律,因而可以得出在洪水位未淹至梁底之前,結(jié)構(gòu)的抗洪安全性能受洪水位高度變化影響不大。3)隨著沖刷深度的增加,結(jié)構(gòu)發(fā)生各損傷等級的概率將迅速增大;且各損傷等級的超越概率對洪水流速較為敏感,也即隨著洪水流速增加,發(fā)生對應(yīng)損傷等級所需要的沖刷深度將明顯減小;對應(yīng)同一沖刷深度,發(fā)生某一損傷等級的超越概率將顯著加大,這也意味著結(jié)構(gòu)更易損傷甚至損毀。4)結(jié)構(gòu)的安全性能與洪水流速以及沖刷深度較為密切。對于橋梁的管養(yǎng)而言,對下部結(jié)構(gòu)進行補強加固,采取相關(guān)措施減緩沖刷侵蝕的發(fā)生,將是提高結(jié)構(gòu)在洪水環(huán)境下的安全性能的重要手段。
[Abstract]:As an important hub in the transportation lifeline system, bridge plays an important role in the daily life of the society. For bridges across the river, flood is one of the main causes of bridge collapse and damage. The frequency of the flood is far higher than the earthquake, which usually brings large scale river flow scour, thus causing severe river bed changes. Scour can not produce direct action load on bridge structure, but it poses a potential threat to the safety of bridge, which will make the bridge more easily damaged under flood, debris flow, earthquake and so on. Therefore, it is necessary to study the safety of bridge structure under flood environment. Vulnerability analysis is a kind of evaluation structure safety. The method of performance has been widely used in the seismic analysis of the structure, and has made great achievements. However, it is rarely concerned about the analysis and evaluation of the vulnerability of bridges under flood environment. Therefore, this paper will try to use the vulnerability analysis to evaluate the safety of bridges under flood environment and to the allusion to the flood environment. This paper first reviews the research status of scholars at home and abroad in the fields of flood disaster, scour and vulnerability, and then describes the basic theory of vulnerability analysis and the selection of structural damage indexes, and puts forward the improvement of the study on the performance of bridge flood resistance. Mixed vulnerability analysis method. Taking the Taiwan double circle bridge as an example, the calculation model of its substructure is established by the Opensees finite element analysis platform. The third chapters in this paper mainly introduce the unit algorithm in Opensees, the nonlinear finite element analysis theory and the closing of the double circle bridge calculation model. The key parameters and problems to be paid attention to, including the treatment of pile working, the simplification of pile group effect and the application of flood load, are introduced in the fourth chapter. In the fourth chapter, the uncertainty of the flood water level and the depth of the scour of the pile foundation is introduced. The random pushover analysis method is used to calculate the structure of the multi variable random function. The flood level height, the probability distribution of flood resistance under different scour depth. The fifth chapter considers the flood water level, the scour depth and the uncertainty of the flood load, and uses the first time moment method (FORM) in the finite element reliability analysis method to obtain the probability distribution of the structural flood resistance in 96 cases. The sixth chapter is combined with the former two. In the second chapter, the result of the improved mixed vulnerability analysis method proposed in this paper is to draw up the vulnerability curve of four flood water levels and three flood flow velocities in all 12 cases, and to evaluate the safety performance of the bridge. The analysis results can be used as an important reference for the decision. The main conclusions obtained in this paper are: 1) this paper The result of the calculation coincides with the case of the 2009 Taiwan double round bridge which has been destroyed by the flood. It also shows that it is feasible to use the analysis idea of vulnerability to evaluate the safety performance of the structure. The qualitative judgment and quantitative parameter analysis can be given according to the specific research object. The calculation results can be used as a reference basis for decision making, and the results can be used as a reference for the decision. .2) the vulnerability curve of the same flood water level at the same flood water level has similar statistical parameters, showing a similar law. Therefore, it can be concluded that the safety performance of the structure is less affected by the height of the flood water level before the flood level is not flooded to the bottom of the beam. With the increase of the depth of the scour, the structure has various damage. The probability of the grade will increase rapidly, and the transcendental probability of each damage grade is more sensitive to the flood flow velocity, that is, the scour depth required for the damage level will be significantly reduced with the increase of the flood flow velocity, and the transcendental probability of a certain damage level will be significantly increased with the same scour depth, which also means that the structure is more vulnerable. The safety performance of the structure is more closely related to the flood flow velocity and the scour depth. For the pipe raising of the bridge, it is an important means to improve the safety performance of the structure in the flood environment by strengthening and strengthening the substructure and taking relevant measures to mitigate the occurrence of erosion erosion.
【學(xué)位授予單位】：西南交通大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：U443.15
本文編號：2166266
[Abstract]:As an important hub in the transportation lifeline system, bridge plays an important role in the daily life of the society. For bridges across the river, flood is one of the main causes of bridge collapse and damage. The frequency of the flood is far higher than the earthquake, which usually brings large scale river flow scour, thus causing severe river bed changes. Scour can not produce direct action load on bridge structure, but it poses a potential threat to the safety of bridge, which will make the bridge more easily damaged under flood, debris flow, earthquake and so on. Therefore, it is necessary to study the safety of bridge structure under flood environment. Vulnerability analysis is a kind of evaluation structure safety. The method of performance has been widely used in the seismic analysis of the structure, and has made great achievements. However, it is rarely concerned about the analysis and evaluation of the vulnerability of bridges under flood environment. Therefore, this paper will try to use the vulnerability analysis to evaluate the safety of bridges under flood environment and to the allusion to the flood environment. This paper first reviews the research status of scholars at home and abroad in the fields of flood disaster, scour and vulnerability, and then describes the basic theory of vulnerability analysis and the selection of structural damage indexes, and puts forward the improvement of the study on the performance of bridge flood resistance. Mixed vulnerability analysis method. Taking the Taiwan double circle bridge as an example, the calculation model of its substructure is established by the Opensees finite element analysis platform. The third chapters in this paper mainly introduce the unit algorithm in Opensees, the nonlinear finite element analysis theory and the closing of the double circle bridge calculation model. The key parameters and problems to be paid attention to, including the treatment of pile working, the simplification of pile group effect and the application of flood load, are introduced in the fourth chapter. In the fourth chapter, the uncertainty of the flood water level and the depth of the scour of the pile foundation is introduced. The random pushover analysis method is used to calculate the structure of the multi variable random function. The flood level height, the probability distribution of flood resistance under different scour depth. The fifth chapter considers the flood water level, the scour depth and the uncertainty of the flood load, and uses the first time moment method (FORM) in the finite element reliability analysis method to obtain the probability distribution of the structural flood resistance in 96 cases. The sixth chapter is combined with the former two. In the second chapter, the result of the improved mixed vulnerability analysis method proposed in this paper is to draw up the vulnerability curve of four flood water levels and three flood flow velocities in all 12 cases, and to evaluate the safety performance of the bridge. The analysis results can be used as an important reference for the decision. The main conclusions obtained in this paper are: 1) this paper The result of the calculation coincides with the case of the 2009 Taiwan double round bridge which has been destroyed by the flood. It also shows that it is feasible to use the analysis idea of vulnerability to evaluate the safety performance of the structure. The qualitative judgment and quantitative parameter analysis can be given according to the specific research object. The calculation results can be used as a reference basis for decision making, and the results can be used as a reference for the decision. .2) the vulnerability curve of the same flood water level at the same flood water level has similar statistical parameters, showing a similar law. Therefore, it can be concluded that the safety performance of the structure is less affected by the height of the flood water level before the flood level is not flooded to the bottom of the beam. With the increase of the depth of the scour, the structure has various damage. The probability of the grade will increase rapidly, and the transcendental probability of each damage grade is more sensitive to the flood flow velocity, that is, the scour depth required for the damage level will be significantly reduced with the increase of the flood flow velocity, and the transcendental probability of a certain damage level will be significantly increased with the same scour depth, which also means that the structure is more vulnerable. The safety performance of the structure is more closely related to the flood flow velocity and the scour depth. For the pipe raising of the bridge, it is an important means to improve the safety performance of the structure in the flood environment by strengthening and strengthening the substructure and taking relevant measures to mitigate the occurrence of erosion erosion.
【學(xué)位授予單位】：西南交通大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：U443.15
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