本文選題：低路堤 + 車輛荷載　； 參考：《長(zhǎng)安大學(xué)》2015年博士論文

【摘要】：低路堤填筑高度小、工程量和占用土地少,可節(jié)約寶貴的土地資源,且易與自然景觀融為一體,對(duì)自然生態(tài)環(huán)境影響小,已成為我國(guó)公路建設(shè)發(fā)展的一個(gè)重要方向。但是由于對(duì)低路堤在車輛荷載作用下的工程特性缺乏了解,在設(shè)計(jì)過(guò)程中參數(shù)選取不盡合理,導(dǎo)致路基發(fā)生較大沉降和路面開(kāi)裂,降低了道路的服務(wù)水平,因此明確低路堤在車輛荷載作用下的工程特性對(duì)指導(dǎo)低路堤的設(shè)計(jì)與施工具有重要的理論意義和工程實(shí)用價(jià)值。本文依托交通運(yùn)輸部西部交通建設(shè)科技項(xiàng)目“新疆綠洲、荒漠地區(qū)干線公路路基合理高度研究”,采用室內(nèi)試驗(yàn)、模型試驗(yàn)、數(shù)值模擬和理論分析等方法對(duì)低路堤在車輛荷載作用下的工程特性進(jìn)行了系統(tǒng)地研究,主要研究?jī)?nèi)容及成果如下:1.采用四分之一車輛模型,考慮輪胎阻尼和路面不平度的影響以及車輛荷載的循環(huán)特征,得到了車輛附加動(dòng)荷載和車輛動(dòng)荷載的表達(dá)式。2.進(jìn)行了動(dòng)三軸試驗(yàn),系統(tǒng)研究了新疆風(fēng)積沙和礫類土的動(dòng)應(yīng)力-動(dòng)應(yīng)變關(guān)系、動(dòng)彈性模量、阻尼比、臨界動(dòng)應(yīng)力和動(dòng)強(qiáng)度,總結(jié)了圍壓、含水率、壓實(shí)度、動(dòng)荷載作用頻率以及初始靜偏應(yīng)力對(duì)風(fēng)積沙和礫類土的動(dòng)應(yīng)力-動(dòng)應(yīng)變關(guān)系、動(dòng)彈性模量、阻尼比的影響規(guī)律,提出了動(dòng)應(yīng)力-動(dòng)應(yīng)變關(guān)系雙曲線模型、動(dòng)彈性模量-應(yīng)變關(guān)系冪函數(shù)模型和動(dòng)強(qiáng)度-作用次數(shù)關(guān)系指數(shù)曲線模型,確定了不同條件時(shí)風(fēng)積沙和礫類土的臨界動(dòng)應(yīng)力。3.開(kāi)展了3種地基狀態(tài)時(shí)礫類土低路堤和風(fēng)積沙低路堤模型試驗(yàn),通過(guò)改變加載大小和頻率模擬不同軸重和不同行駛速度的車輛荷載,研究了低路堤在靜載、短時(shí)動(dòng)載和長(zhǎng)時(shí)動(dòng)載作用下的工程特性,得到了路基和地基范圍內(nèi)各深度處的應(yīng)力、各結(jié)構(gòu)層的應(yīng)變以及應(yīng)力的傳遞衰減特性。明確了靜載大小、動(dòng)荷載峰值、動(dòng)荷載作用頻率、動(dòng)荷載作用次數(shù)、地基含水率和路基填料對(duì)低路堤工程特性的影響規(guī)律,分析了低路堤在靜載、短時(shí)動(dòng)載和長(zhǎng)時(shí)動(dòng)載作用下工程特性的差異,提出了長(zhǎng)時(shí)動(dòng)載作用下低路堤動(dòng)應(yīng)力累積模型。4.建立了車-路三維動(dòng)力分析有限元模型,通過(guò)現(xiàn)場(chǎng)實(shí)測(cè)數(shù)據(jù)和模型試驗(yàn)結(jié)果驗(yàn)證了模型的正確性,基于該模型分析了路堤高度和模量、基層厚度和模量、面層厚度和模量、車輛移動(dòng)速度、超載率和路面不平度等因素對(duì)車輛荷載作用下低路堤不同深度處動(dòng)應(yīng)力和路基工作區(qū)的影響。5.基于層狀結(jié)構(gòu)下靜載的傳遞和擴(kuò)散公式,依據(jù)低路堤模型試驗(yàn)和數(shù)值模擬分析結(jié)果,考慮車輛荷載行駛速度、路面不平度、超載、累積效應(yīng)以、道路結(jié)構(gòu)和應(yīng)力衰減的影響,推導(dǎo)了低路堤動(dòng)應(yīng)力的計(jì)算公式。應(yīng)用該公式給出了新疆低路堤地基換填加固參數(shù)的取值。
[Abstract]:The low embankment construction height is small, the engineering quantity and the occupation land is little, can save the precious land resources, and is easy to merge with the natural landscape, the influence to the natural ecological environment is small, has already become an important direction of the highway construction development of our country. However, due to the lack of understanding of the engineering characteristics of the low embankment under vehicle load, and the unreasonable selection of parameters in the design process, the subgrade has a large settlement and pavement cracking, which reduces the service level of the road. Therefore, it is of great theoretical significance and practical value to clarify the engineering characteristics of low embankment under vehicle load for guiding the design and construction of low embankment. This paper relies on the scientific and technological project of western traffic construction of Ministry of Communications and Transport, "study on reasonable height of highway roadbed in oasis and desert area of Xinjiang", adopts indoor test and model test, The engineering characteristics of low embankment under vehicle load are systematically studied by numerical simulation and theoretical analysis. The main contents and results are as follows: 1. Based on the model of 1/4 vehicle, considering the influence of tire damping and road roughness, and the cyclic characteristics of vehicle load, the expressions of additional dynamic load and dynamic load of vehicle are obtained. Dynamic triaxial tests were carried out. The dynamic stress-strain relationship, dynamic elastic modulus, damping ratio, critical dynamic stress and dynamic strength of aeolian sand and gravel soil in Xinjiang were systematically studied, and the confining pressure, moisture content, compaction degree were summarized. A hyperbolic model of dynamic stress-strain relation, dynamic modulus of elasticity and damping ratio is proposed, which is influenced by the frequency of dynamic load and the initial static deflection stress on the dynamic stress-strain relationship of aeolian sand and gravel soil. The power function model of dynamic elastic modulus-strain relationship and the exponential curve model of dynamic intensity-action times are used to determine the critical dynamic stress of aeolian sand and gravel soil under different conditions. The model tests of low gravel embankment and eolian sand low embankment under three kinds of foundation conditions were carried out. The static load of low embankment was studied by changing the loading size and frequency to simulate the vehicle loads with different axle loads and different driving speeds. Under the action of short-time dynamic load and long-time dynamic load, the stress at each depth, the strain of each structural layer and the transmission and attenuation characteristics of stress in the subgrade and foundation are obtained under the action of short-time dynamic load and long-time dynamic load. The influence of static load, peak dynamic load, frequency of dynamic load, moisture content of foundation and filling of subgrade on the engineering characteristics of low embankment are defined. The static load of low embankment is analyzed. The dynamic stress accumulation model of low embankment under the action of long time dynamic load and short time dynamic load is proposed. The finite element model of three-dimensional dynamic analysis of vehicle-road is established, and the correctness of the model is verified by the field measured data and model test results. Based on the model, the height and modulus of embankment, the thickness and modulus of base course, the thickness and modulus of surface layer are analyzed. The effect of moving speed, overload rate and road roughness on dynamic stress at different depths of low embankment and subgrade working area under vehicle load. Based on the formula of static load transfer and diffusion under layered structure, according to the results of model test and numerical simulation analysis of low embankment, the effects of vehicle load speed, road roughness, overload, cumulative effect on road structure and stress attenuation are considered. The formula for calculating dynamic stress of low embankment is derived. The formula is used to give the values of the parameters for the replacement and reinforcement of the foundation of Xinjiang low embankment.
【學(xué)位授予單位】：長(zhǎng)安大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2015
【分類號(hào)】：U416.1

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本文編號(hào)：1985849