本文關(guān)鍵詞：斜坡軟弱地基路堤工程特性及其雙指標(biāo)設(shè)計(jì)體系研究　出處：《西南交通大學(xué)》2014年博士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 斜坡軟弱地基路堤 側(cè)向變形 豎向沉降 穩(wěn)定性 地基變形系數(shù) 非線性有限元 雙指標(biāo)設(shè)計(jì)體系 抗滑樁

【摘要】：中國(guó)幅員遼闊,丘陵和山地廣泛分布,交通基礎(chǔ)設(shè)施建設(shè)中頻繁遇到斜坡軟弱地基路堤工程。因斜坡軟弱地基的特殊性,易出現(xiàn)垮塌失穩(wěn)、地基側(cè)向變形過(guò)大等典型病害。本文通過(guò)文獻(xiàn)閱讀、工程調(diào)研,在全面地回顧、評(píng)述斜坡軟弱地基路堤工程最新研究進(jìn)展的基礎(chǔ)上,運(yùn)用精細(xì)化數(shù)值仿真技術(shù),基于巖土工程計(jì)算力學(xué)軟件P1axis和FLAC3D,依托室內(nèi)土工離心模型試驗(yàn)及現(xiàn)場(chǎng)測(cè)試的研究成果,系統(tǒng)地研究了斜坡軟弱地基路堤的變形和穩(wěn)定性等工程特性,提出了兼顧“變形”與“穩(wěn)定”的斜坡軟弱地基路堤雙指標(biāo)設(shè)計(jì)體系,歸納總結(jié)了斜坡軟弱地基路堤的工程處治對(duì)策。論文所取得的主要研究成果如下：(1)結(jié)合國(guó)內(nèi)公路、鐵路、巖土等行業(yè)規(guī)范,從成因、分布、工程特性等方面入手,較系統(tǒng)地比較了“斜坡軟土”與一般“軟土”的異同,明確了“斜坡軟土”的概念,并嘗試提出了“斜坡軟土”相應(yīng)的判別標(biāo)準(zhǔn)。(2)運(yùn)用非線性有限元法,建立斜坡軟弱地基在路堤自重荷載作用下的數(shù)值分析模型,模擬了路堤分步建造的施工力學(xué)行為,從土體變形和穩(wěn)定安全性兩方面進(jìn)行研究,并結(jié)合土工離心模型試驗(yàn)成果,綜合論證了表層軟弱層、地面橫坡對(duì)路基結(jié)構(gòu)工程特性的影響。結(jié)果表明：斜坡軟弱地基不能簡(jiǎn)單看成斜坡地基和軟弱地基的等權(quán)重線性疊加；表層軟弱層、地面橫坡加劇了地基的側(cè)向變形、豎向沉降,改變了潛在滑移面的形態(tài),導(dǎo)致路堤結(jié)構(gòu)穩(wěn)定性降低,工程中應(yīng)高度重視下坡腳處的側(cè)向變形以及對(duì)表層軟弱層的處理。(3)基于彈塑性平面應(yīng)變有限單元法,建立了斜坡軟弱地基在路堤荷載作用下的數(shù)值分析模型,真實(shí)模擬了路堤水平分層分步填筑的動(dòng)態(tài)施工力學(xué)行為,獲得普通水平地基、水平軟弱地基、普通斜坡地基及斜坡軟弱地基四種工況下地基的側(cè)向變形與豎向沉降隨路堤填筑施工的動(dòng)態(tài)變化規(guī)律。引入地基變形系數(shù),分析了地基側(cè)向變形與豎向沉降之間的相互耦合、制約關(guān)系,奠定基于側(cè)向變形控制的斜坡軟弱地基路堤設(shè)計(jì)原則的理論基礎(chǔ),結(jié)合土工離心模型試驗(yàn)所獲得的地基變形系數(shù)及位移場(chǎng),討論了打入樁與抗滑樁加固斜坡軟弱地基路堤的機(jī)理。結(jié)果表明：引入無(wú)量綱化的地基變形系數(shù),并通過(guò)其隨路堤分層分步建造而變化的趨勢(shì),包括單調(diào)性、陡緩性、與1.0之間的大小關(guān)系等,可科學(xué)描述地基側(cè)向變形與豎向沉降之間的相互耦合、制約關(guān)系,能有效指導(dǎo)工程對(duì)策選用；打入樁、抗滑樁加固斜坡軟弱地基路堤機(jī)理不同,打入樁主要是控制斜坡軟弱地基豎向沉降,同時(shí)可適當(dāng)抑制側(cè)向變形；抗滑樁主要是抑制側(cè)向變形,對(duì)沉降控制作用有限。(4)運(yùn)用非線性有限元法建立斜坡軟弱地基在路堤自重荷載作用下的數(shù)值模型,探討了軟弱層特性各因素對(duì)斜坡軟弱地基路堤變形的影響,通過(guò)正交試驗(yàn)設(shè)計(jì),評(píng)價(jià)了軟弱層特性各因素對(duì)變形影響的顯著性。結(jié)果表明：軟弱層土體模量、軟弱層厚度是產(chǎn)生過(guò)大豎向沉降和側(cè)向變形的決定性因素；地面橫坡的存在,是加劇地基變形的重要因素；當(dāng)軟弱層位于地基頂面時(shí),其對(duì)地基變形,尤其是側(cè)向變形影響顯著；軟弱層特性各因素對(duì)側(cè)向變形和豎向沉降的影響權(quán)重不一致；宜綜合考慮軟弱層特性多因素的影響,采取地基處理、側(cè)向約束等工程對(duì)策限制變形。(5)因現(xiàn)行技術(shù)規(guī)范尚未明確定義斜坡軟弱地基的概念及工程處治對(duì)策,或僅通過(guò)調(diào)整單一影響參數(shù)的試算方法嘗試修正考慮地層坡度的穩(wěn)定安全系數(shù)容許值。為準(zhǔn)確獲取斜坡軟弱地基變形和路堤穩(wěn)定性的內(nèi)在聯(lián)系,運(yùn)用彈塑性有限元法,建立了斜坡軟弱地基在路堤自重荷載作用下的數(shù)值模型,根據(jù)彈塑性變形所獲的地基變形系數(shù)以及剪切強(qiáng)度折減法所獲的穩(wěn)定安全系數(shù),結(jié)合渝懷鐵路實(shí)際工點(diǎn)的現(xiàn)場(chǎng)測(cè)試成果,構(gòu)建了兼顧“變形”與“穩(wěn)定”的斜坡軟弱地基路堤雙指標(biāo)設(shè)計(jì)體系,論證了該體系的科學(xué)性、可操作性,提出了該設(shè)計(jì)體系的實(shí)際運(yùn)用步驟。結(jié)果表明：兼顧“變形”與“穩(wěn)定”的斜坡軟弱地基路堤雙指標(biāo)設(shè)計(jì)體系可更真實(shí)地反映路堤的穩(wěn)定狀態(tài)及變形發(fā)展趨勢(shì),有效指導(dǎo)工程設(shè)計(jì)及施工(6)鑒于在路堤下坡腳處采用鋼筋混凝土抗滑樁可有效限制地基側(cè)向變形,是斜坡軟弱地基路堤的核心設(shè)計(jì)原則之一。采用三維快速拉格朗日有限差分法,經(jīng)與室內(nèi)土工離心模型試驗(yàn)成果對(duì)比、校核,建立了抗滑樁加固斜坡軟弱地基路堤的精細(xì)化數(shù)值分析模型,研究了抗滑樁樁距、樁長(zhǎng)、樁身彈性模量、樁身橫截面尺寸及樁位等設(shè)計(jì)參數(shù)對(duì)其內(nèi)力、變位的影響。結(jié)果表明：下坡腳處實(shí)施抗滑樁可顯著約束斜坡軟弱地基側(cè)向變形；需綜合考慮樁身受力、經(jīng)濟(jì)性、施工等影響因素以確定合理的樁距；樁身應(yīng)深入滑移面以下,但隨著樁身長(zhǎng)度的增長(zhǎng),加固效果增長(zhǎng)不明顯；隨著樁身彈性模量、樁身橫截面尺寸的增加,抗滑樁的加固效果得到一定提高；抗滑樁宜設(shè)置在下坡側(cè)路堤邊坡的中部。(7)初步提出了斜坡軟弱地基路堤工程處治的基本原則,并從提高地基整體抗變形能力、提高地基抗失穩(wěn)能力、強(qiáng)化路堤本體、采用樁網(wǎng)(樁板)結(jié)構(gòu)等新型結(jié)構(gòu)性路堤以及加強(qiáng)防排水等方面,系統(tǒng)歸納了斜坡軟弱地基路堤的主要工程處治對(duì)策,明確了不同處治措施的適用范圍、適用條件。
[Abstract]:Chinese vast, widely distributed in Hilly and mountainous areas, transportation infrastructure construction frequently encountered the slope of embankment on soft foundation engineering. Because of the particularity of slope weak foundation, prone to collapse instability, the lateral deformation of the soil is too large. Typical disease through literature reading, engineering research, in a comprehensive review, based on the latest research progress on the slope of embankment on soft foundation engineering, using numerical simulation technology of fine, computational mechanics software P1axis and FLAC3D geotechnical engineering based on indoor test and field based on the geotechnical centrifuge model test research results, systematically studied the characteristics of slope deformation and stability of embankment on soft foundation engineering, puts forward the double index system design consideration the deformation and stability of embankment on soft foundation of slope, the slope of embankment on soft foundation engineering treatment measures are summarized. The main research papers made The results are as follows: (1) combined with the domestic highway, railway, geotechnical and other industry standards, from the origin, distribution, engineering properties and other aspects, and systematically compares the "slope soft soil" and "soft", defined the concept of "slope soft soil", and tries to put forward the relevant criteria for soft soil on the slope ". (2) using nonlinear finite element method, a numerical slope weak foundation in embankment under self weight load analysis model, simulation of the construction mechanics behavior of embankment construction step by step, from the two aspects of soil deformation and stability safety research, combined with the results of geotechnical centrifuge model test comprehensive, demonstrates the weak surface layer effect, ground slope characteristics of subgrade engineering structure. The results show that the slope soft foundation slope foundation and not simply as a weak foundation and weighted linear superposition; weak surface layer, ground slope increased The foundation of the lateral displacement, vertical settlement, change the shape of the potential slip plane, which leads to the decrease of embankment structure stability, should attach great importance to the downhill at the foot of the lateral deformation and processing of weak surface layer in engineering. (3) the elastic-plastic plane strain finite element method based on the established numerical analysis model of slope weak foundation in under embankment load, simulate the dynamic construction mechanical behavior of embankment filling level step by step, general level of foundation level, weak foundation, common slope foundation and slope weak foundation lateral foundation under four conditions of deformation and vertical settlement changes with the embankment construction. The subgrade deformation analysis of foundation the lateral coupling deformation and vertical settlement of the relationship between, lay a theoretical foundation for controlling the lateral deformation of the slope of embankment on soft foundation design based on the principle of, The foundation deformation coefficient and displacement field of geotechnical centrifuge model tests of the mechanism of pile and anti slide pile reinforced slope embankment on soft foundation is discussed. The results show that the dimensionless deformation of foundation coefficient varies with embankment and through its hierarchical construction process step trend, including monotonicity, steep slow, 1 and the size of the relationship between science, can describe the lateral deformation of the soil and the vertical settlement of the coupling between, restricted, can effectively guide the selection of engineering measures; driven pile, piles reinforced slope embankment mechanism with driven pile is mainly to control the slope soft foundation settlement, at the same time may be appropriate to inhibit lateral deformation anti slide pile; mainly inhibit lateral deformation, on the control of settlement is limited. (4) is used to establish the numerical model of slope soft foundation under embankment load under the action of nonlinear finite element method To investigate the effect of various factors, the weak layer characteristics of embankment on soft foundation of slope deformation, through the orthogonal experimental design, evaluation of various factors of weak layer characteristics on the significant effect of deformation. The results show that the soft soil layer modulus, thickness of weak layer is a decisive factor in the vertical settlement and lateral deformation of the ground slope; there is an important factor of subgrade deformation; when the soft layer is located in the top surface of foundation, the foundation deformation, especially the lateral deformation effect; weak layer characteristics on the influence factors of the lateral deformation and settlement of the weight is not consistent; should consider the influence of multi factors of weak layer characteristics, take the foundation treatment. The lateral constraint measures limit deformation. (5) because of the concept and project of the current technical specification is not yet clear definition of slope soft foundation treatment measures, or only by adjusting the parameters of the single effect This method attempts to consider correction of allowable value of stability coefficient of slope of formation. As the inner link to accurately obtain the slope soft foundation deformation and stability of embankment, with the elastic-plastic finite element method, a numerical model of slope weak foundation in embankment under gravity load, according to the elastic-plastic deformation of the foundation deformation and shear coefficient strength reduction by the safety factor, combined with the actual test results of the Chongqing Huaihua railway project, construction of a dual index system design taking into account the deformation and stability of embankment on soft foundation of slope, proof of the scientific nature of the system, operation, put forward practical steps of the design system. Show that the double index system design both "deformation" and "stability" of the slope of embankment on soft foundation can reflect the stability of embankment deformation and development trend, effectively Guide the engineering design and construction (6) given in the downhill at the foot of embankment reinforced concrete can effectively limit the lateral deformation of foundation piles, is one of the core principles of design of slope of embankment on soft foundation. Using Lagrange finite difference method, and the indoor geotechnical centrifuge model test results, calculation, analysis model is established fine numerical piles reinforced slope soft foundation embankment, the anti slide pile spacing, pile length, pile modulus, pile cross section size and pile design parameters such as the internal force, displacement effect. The results show that the downhill at the foot of implementation can significantly constrain the lateral deformation of slope weak foundation anti slide pile; axial forces, the need to consider the economic factors affecting the construction of pile, etc. to determine the reasonable pile spacing; pile should be deep slip surface below, but with the increase of the length of the pile, the reinforcement effect of the growth is not obvious With the elastic modulus of pile; pile, increase the size of cross section, anti slide pile reinforcement effect can be improved; the anti should be arranged in the middle of the downhill side of the slope of embankment pile. (7) proposed the basic principles of slope embankment engineering soft foundation treatment, and improve the overall ability to resist deformation from the ground. The foundation to improve the anti instability capability, strengthen the embankment, the pile net (plate pile) structure of new embankment and strengthen the anti structural drainage system, summarizes the main engineering slope of embankment on soft foundation treatment measures, clear the applicable scope of different treatment measures of the applicable conditions.

【學(xué)位授予單位】：西南交通大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2014
【分類號(hào)】：U416.12

【參考文獻(xiàn)】

相關(guān)碩士學(xué)位論文 前5條

1 黃明星;樁網(wǎng)結(jié)構(gòu)處治斜坡軟弱地基填方工程效果的數(shù)值分析[D];西南交通大學(xué);2011年

2 漆寶瑞;“斜坡軟土”特性及工程措施研究[D];西南交通大學(xué);2003年

3 劉望坤;山區(qū)高速公路軟土路基變形特性研究[D];重慶交通大學(xué);2013年

4 梁多偉;碎石樁與抗滑樁聯(lián)合加固及非埋式樁板結(jié)構(gòu)加固斜坡軟弱地基路堤的數(shù)值模擬[D];西南交通大學(xué);2013年

5 朱奇炯;基于可靠度的斜坡軟弱地基路堤穩(wěn)定性研究[D];西南交通大學(xué);2013年

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本文編號(hào)：1437824