【摘要】：以重慶雙碑隧道為實(shí)際工程背景，按照該雙碑隧道加寬段與普通段的實(shí)際開(kāi)挖斷面尺寸、圍巖和初期支護(hù)材料參數(shù)以及施工方法，采用大型有限元軟件邁達(dá)斯GTS模擬隧道加寬帶施工過(guò)程，分析雙碑隧道加寬帶僅在初期支護(hù)的作用下圍巖的穩(wěn)定性、各工況下的安全系數(shù)以及加寬段與普通段結(jié)合處（變截面）的位移，應(yīng)力及支護(hù)參數(shù)的合理性。 ①采用有限元軟件邁達(dá)斯GTS建立二維有限元模型，應(yīng)用強(qiáng)度折減法對(duì)實(shí)際的四種工況（埋深100m III級(jí)圍巖雙洞、埋深100mIV級(jí)圍巖雙洞（臺(tái)階法）、埋深100mIV級(jí)圍巖雙洞（雙側(cè)壁法）、埋深在150mIV級(jí)圍巖單洞）下，，對(duì)圍巖及初期支護(hù)做彈塑性數(shù)值模擬分析；重點(diǎn)分析了隧道加寬段的位移隨著強(qiáng)度折減系數(shù)變化的曲線，根據(jù)隧道失穩(wěn)的判據(jù)，得到各工況下的安全系數(shù)；以及在實(shí)際的支護(hù)參數(shù)下，圍巖的位移，應(yīng)力和塑性區(qū)的分布規(guī)律；并對(duì)施工方案進(jìn)行了比選。 ②通過(guò)建立三維有限元模型，在埋深100m III級(jí)圍巖工況下，分析對(duì)雙碑隧道加寬帶與普通段結(jié)合處（變截面）過(guò)渡段的整體穩(wěn)定性，分析過(guò)渡段圍巖在實(shí)際初期支護(hù)參數(shù)下的位移，應(yīng)力和塑性區(qū)特征，同時(shí)分析噴混層的受力情況，得出過(guò)渡段變截面的最不利受力位置。 通過(guò)以上研究方法得到以下結(jié)論： ①各個(gè)工況下加寬段的安全系數(shù)不同，最小值為在埋深在150mIV級(jí)圍巖工況下安全系數(shù)值為2，最大值為埋深100m III級(jí)圍巖雙洞工況下安全系數(shù)為4.6。 ②無(wú)論是從圍巖位移還是從支護(hù)結(jié)構(gòu)應(yīng)力情況，加寬段與普通段結(jié)合處（變截面）最不利位置均在右側(cè)拱腰，水平收斂值達(dá)到開(kāi)挖跨度的0.6%，同時(shí)噴混層出現(xiàn)了拉應(yīng)力，且數(shù)值達(dá)到了0.323Mpa，因此施工時(shí)應(yīng)注意對(duì)變截面處的加固，必要時(shí)可增加端承處的噴射混凝土厚度，或者在端承處也植入錨桿，保證變截面的安全。
[Abstract]:Based on the actual engineering background of Chongqing Shuangbei tunnel, according to the actual excavation section size of the widening section and ordinary section of the tunnel, the parameters of surrounding rock and initial supporting material and the construction method, The large finite element software Midas GTS is used to simulate the construction process of tunnel plus wide band, and the stability of surrounding rock under the action of initial support is analyzed. The safety factor and displacement, stress and support parameters at the joint of widening section and ordinary section (variable section) are reasonable under each working condition. 1 A two-dimensional finite element model is established by using the finite element software Midas GTS. The strength reduction method is applied to the actual four working conditions (100m deep III class wall rock double hole, buried depth 100mIV class wall rock double hole (step method), buried depth 100mIV class surrounding rock double hole (double lateral wall method), buried depth in 150mIV class surrounding rock single hole). Elastoplastic numerical simulation analysis of surrounding rock and initial support is made, and the curve of displacement with strength reduction coefficient in widening section of tunnel is analyzed emphatically. According to the criterion of tunnel instability, the safety factor under each working condition is obtained. And the distribution law of displacement, stress and plastic zone of surrounding rock under the actual supporting parameters. 2 through the establishment of three-dimensional finite element model, under the condition of 100m III surrounding rock, This paper analyzes the overall stability of the transition section (variable section) in the joint of double tablet tunnel with wide band and common section, analyzes the displacement, stress and plastic zone characteristics of the surrounding rock of the transition section under the actual initial supporting parameters, and analyzes the stress situation of the shotcrete layer at the same time. The most unfavorable force position of the transition section is obtained. The conclusions are as follows: (1) the safety factor of the widening section is different under different working conditions. The minimum value is that the safety coefficient of buried depth is 2 under the condition of 150mIV class surrounding rock, and the maximum value is 100 m III grade surrounding rock under double tunnel condition. The safety factor is 4.6 2 whether from the displacement of surrounding rock or from the stress of supporting structure. The most unfavorable position at the joint (variable section) of the widening section and the common section is in the right arch waist, the horizontal convergence value reaches 0.6 of the excavation span, and the tensile stress appears in the mixing layer and the value reaches 0.323 Mpa.Therefore, attention should be paid to the reinforcement of the variable section in construction. The thickness of shotcrete can be increased when necessary, or anchors can be inserted at the end supports to ensure the safety of variable sections.
【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】：2014
【分類(lèi)號(hào)】：U452.1;U458

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