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山區(qū)沿河公路懸空路面板三維斷裂機(jī)制研究

發(fā)布時(shí)間:2018-10-31 11:33
【摘要】:西南地區(qū)主要為山地丘陵地貌,夏季降雨豐沛,為山洪、泥石流等地質(zhì)災(zāi)害的孕育創(chuàng)造了地理優(yōu)勢(shì)。沿河公路依山傍水,地質(zhì)災(zāi)害頻發(fā),公路洪災(zāi)損失嚴(yán)重,混凝土懸空路面板即是公路水毀典型形式中的一種常見(jiàn)形態(tài)。本文以沿河公路懸空路面板為研究對(duì)象,利用復(fù)合材料等效原理、有限元模擬、彈性地基薄板理論、斷裂力學(xué)、材料力學(xué)等知識(shí),分析其在自重和車(chē)輛荷載作用下的三維斷裂破壞機(jī)制。根據(jù)路面板懸空程度,結(jié)合路面裂紋狀況,得出了混凝土懸空路面板的極限承載力,并據(jù)此劃分出安全行車(chē)區(qū)域,通過(guò)交通管制,限定通行車(chē)輛荷載和通行區(qū)域,防止懸空混凝土路面板發(fā)生突然的脆性斷裂破壞,以保障人民生命財(cái)產(chǎn)安全。取得主要成果如下:(1)基于復(fù)合材料理論,采用細(xì)觀力學(xué)的方法,以混凝土懸空路面板裂紋擴(kuò)展規(guī)律為依據(jù),得出了并串聯(lián)模型和串聯(lián)體模型兩種等效混凝土彈性模量預(yù)估計(jì)算方法,在優(yōu)化的基礎(chǔ)上實(shí)現(xiàn)了將鋼筋混凝土懸空路面板等效為均質(zhì)板的過(guò)程,為有限元分析和理論分析提供支撐。(2)運(yùn)用ANSYS有限元模擬,對(duì)平行懸空和角部懸空混凝土路面板進(jìn)行數(shù)值模擬,考慮懸空比例、車(chē)輛軸載、車(chē)輛荷位的因素,分析其應(yīng)力場(chǎng)分布,獲得了最大拉應(yīng)力分布規(guī)律和最不利車(chē)輛荷位,為理論分析奠定基礎(chǔ)。(3)基于Winkler彈性地基薄板理論,借鑒Westerggard分析無(wú)限大板荷載應(yīng)力思路,將平行懸空路面板通過(guò)力學(xué)簡(jiǎn)化處理,轉(zhuǎn)化為非懸空有限尺寸路面板模型,進(jìn)一步求得受剪面上拉應(yīng)力公式。(4)按照斷裂力學(xué)方法,采用帶表生裂紋的三維斷裂模型,求得平行懸空路面板在自重和車(chē)輛荷載作用下的極限承載力公式。(5)按照材料力學(xué)的方法計(jì)算剛性路面荷載應(yīng)力,得到了角部懸空路面板拉應(yīng)力計(jì)算公式,結(jié)合斷裂力學(xué)的方法,采用帶表生裂紋的三維斷裂模型,求得角部懸空路面板在自重和車(chē)輛荷載作用下的極限承載力公式。
[Abstract]:The southwest area is mainly mountainous and hilly geomorphology with abundant rainfall in summer, which creates geographical advantages for geological disasters such as mountain torrents and debris flows. The highway along the river is leaning against the mountain and water, geological disasters occur frequently, the flood damage of the highway is serious, and the concrete suspended slab is one of the typical forms of highway water damage. Based on the theory of composite equivalent, finite element simulation, thin plate theory of elastic foundation, fracture mechanics, material mechanics, etc. The three-dimensional fracture failure mechanism under the action of deadweight and vehicle load is analyzed. According to the suspended degree of the pavement slab and the crack condition of the pavement, the ultimate bearing capacity of the concrete suspended pavement slab is obtained, and the safe driving area is divided according to this, and the traffic load and the traffic area are limited by traffic control. In order to protect the life and property of the people, it can prevent the sudden brittle fracture and damage of the suspended concrete pavement slab. The main achievements are as follows: (1) based on the theory of composite materials, the method of meso-mechanics is adopted, and the law of crack growth of concrete suspended pavement slab is taken as the basis. In this paper, two kinds of equivalent concrete elastic modulus estimation methods, parallel series model and series body model, are obtained. On the basis of optimization, the process of equating reinforced concrete suspended slab to homogeneous slab is realized. It provides support for finite element analysis and theoretical analysis. (2) using ANSYS finite element simulation, the parallel suspension and corner suspension concrete pavement are numerically simulated, considering the factors of suspension ratio, vehicle axle load, vehicle load position, etc. The maximum tensile stress distribution law and the most unfavorable vehicle load position are obtained by analyzing the stress field distribution. (3) based on the Winkler elastic foundation thin plate theory, Westerggard is used to analyze the load stress of infinite plate. The parallel suspended road slab is simplified by mechanics and transformed into a non-suspended finite size road panel model, and the formula of tensile stress on the shear plane is obtained. (4) according to the method of fracture mechanics, the three-dimensional fracture model with apparent crack is adopted. The formula of ultimate bearing capacity of parallel suspended road slab under the action of deadweight and vehicle load is obtained. (5) according to the method of material mechanics, the load stress of rigid pavement is calculated, and the formula for calculating tensile stress of corner suspended road slab is obtained. Combined with the method of fracture mechanics, a three-dimensional fracture model with surface crack is used to obtain the ultimate bearing capacity formula of the corner suspended road slab under the action of deadweight and vehicle load.
【學(xué)位授予單位】:重慶交通大學(xué)
【學(xué)位級(jí)別】:碩士
【學(xué)位授予年份】:2015
【分類(lèi)號(hào)】:U418.54

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