本文關(guān)鍵詞：既有線附近基坑開(kāi)挖對(duì)其路基變形的影響及支護(hù)效果的分析研究　出處：《蘭州交通大學(xué)》2014年碩士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 既有路基 基坑開(kāi)挖 變形 穩(wěn)定性 支護(hù)

【摘要】：隨著公路和鐵路網(wǎng)的逐步完善,新建線路與既有線不可避免會(huì)形成交叉。在跨既有線橋梁施工中,基坑的開(kāi)挖會(huì)導(dǎo)致既有路基發(fā)生變形和失穩(wěn),甚至影響行車安全。 本文結(jié)合津秦鐵路特大橋跨既有線鐵路橋的施工,以橋墩承臺(tái)基坑開(kāi)挖為工程背景,依據(jù)Mohr-Coulomb屈服準(zhǔn)則,采用FLAC3D軟件作為計(jì)算工具建立了動(dòng)、靜載數(shù)值分析模型,探討了基坑開(kāi)挖的不同距離、角度、深度以及路基高度等參數(shù)對(duì)既有線的路基變形的影響,分析了基坑開(kāi)挖中支護(hù)前后既有路基變形的影響規(guī)律。主要完成以下幾方面工作： (1)通過(guò)查閱文獻(xiàn)資料,了解基坑開(kāi)挖引起周圍構(gòu)筑物變形的特點(diǎn),對(duì)基坑開(kāi)挖引起的主要變形以及地表沉降的計(jì)算方法進(jìn)行綜述。 (2)結(jié)合單線鐵路路基模型,采用有限差分法進(jìn)行數(shù)值分析,將列車荷載等效為靜荷載分析在有無(wú)支護(hù)的情況下均質(zhì)土層中基坑開(kāi)挖參數(shù)變化對(duì)既有路基變形的影響,得到基坑施工中無(wú)支護(hù)情況下的臨界開(kāi)挖距離和臨界開(kāi)挖深度以及既有路基變形隨開(kāi)挖角度和路基高度的變化規(guī)律；并對(duì)不同開(kāi)挖距離、開(kāi)挖角度、開(kāi)挖深度以及路基高度的支護(hù)效果進(jìn)行分析。 (3)將列車荷載以激振力函數(shù)作用于上述模型,對(duì)既有路基進(jìn)行基坑開(kāi)挖的動(dòng)態(tài)數(shù)值模擬,分析不同參數(shù)對(duì)支護(hù)后既有路基變形的影響。并將靜態(tài)與動(dòng)態(tài)模擬結(jié)果進(jìn)行對(duì)比,結(jié)果表明：兩種模擬方式下各參數(shù)對(duì)路基的變形影響規(guī)律基本一致,路基沉降主要由荷載的作用方式及范圍決定,路基的水平位移與荷載的作用方式關(guān)系不大,主要受基坑開(kāi)挖的影響。 (4)按照?qǐng)A弧滑移面法基本原理,針對(duì)上述分析模型在不同開(kāi)挖參數(shù)下基坑穩(wěn)定性分析,得到支護(hù)前后各種工況下的基坑開(kāi)挖時(shí)的穩(wěn)定性系數(shù),并對(duì)基坑穩(wěn)定臨界條件進(jìn)行探索。
[Abstract]:With the gradual improvement of highway and railway network, new lines and existing lines will inevitably cross. In the construction of bridges with existing lines, excavation of foundation pit will lead to deformation and instability of existing subgrade. Even affect the safety of driving. Based on the foundation pit excavation of pier cap and Mohr-Coulomb yield criterion, this paper combined with the construction of the railway bridge over the existing railway line on the Jin-Qin railway, taking the excavation of the foundation pit of the pier cap as the engineering background. The dynamic and static load numerical analysis models are established by using FLAC3D software, and the influence of different distance, angle, depth and subgrade height of foundation pit excavation on the subgrade deformation of the existing railway is discussed. This paper analyzes the influence law of existing subgrade deformation before and after supporting in excavation of foundation pit, and mainly accomplishes the following work: 1) the characteristics of deformation of surrounding structures caused by excavation of foundation pit are understood, and the main deformation caused by excavation of foundation pit and the calculation methods of surface settlement are summarized. Combined with the single-track railway subgrade model, the finite difference method is used to carry out the numerical analysis. The train load is equivalent to static load to analyze the influence of excavation parameters of foundation pit in homogeneous soil layer on the deformation of existing subgrade under the condition of supporting or not. The variation law of the critical excavation distance, critical excavation depth and existing roadbed deformation with the excavation angle and the roadbed height in the case of no supporting in foundation pit construction is obtained. The support effect of different excavation distance, excavation angle, excavation depth and roadbed height is analyzed. 3) the dynamic numerical simulation of foundation pit excavation of existing roadbed is carried out by applying train load to the above model with exciting force function. This paper analyzes the influence of different parameters on the deformation of existing roadbed after supporting, and compares the static and dynamic simulation results. The results show that the influence of each parameter on the deformation of roadbed is basically the same under the two simulation modes. The settlement of subgrade is mainly determined by the mode and range of load, but the horizontal displacement of subgrade is not related to the mode of load, but is mainly affected by excavation of foundation pit. 4) according to the basic principle of circular slip surface method, the stability coefficient of foundation pit under various conditions before and after supporting is obtained according to the stability analysis of foundation pit under different excavation parameters according to the above analysis model. The critical condition of foundation pit stability is explored.
【學(xué)位授予單位】：蘭州交通大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：U445.55;U213.1

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本文編號(hào)：1390668