本文選題：軟弱圍巖 + 新意法�。� 參考：《北京交通大學(xué)》2014年碩士論文

【摘要】：摘要：軟弱圍巖地質(zhì)條件下的隧道施工,是隧道工程界面臨的重要難題之一。軟弱圍巖具有變形大、變形速度快、變形難以控制等特點,由于隧道施工中對軟弱圍巖隧道的變形機理、發(fā)展演化規(guī)律等認識不足,采取的控制技術(shù)與方法缺乏針對性,軟弱圍巖的隧道開挖面臨諸多困難。巖土控制變形分析法為解決軟弱圍巖隧道施工中的變形控制提供了新的思路,本文根據(jù)巖土變形分析法(即新意法)的指導(dǎo)思想,在國家自然科學(xué)基金項目“含水弱膠結(jié)砂巖隧道預(yù)筑拱荷載特性及開挖面穩(wěn)定性研究(NO.51178026)”的支持下,對機械預(yù)切槽技術(shù)施作形成的預(yù)筑拱支護特性進行了詳細深入的研究,通過ANSYS有限元計算、FLAC3D數(shù)值模擬、理論解析等手段,研究了預(yù)筑拱的合理支護參數(shù)、預(yù)筑拱控制軟弱圍巖變形的機理及特性、預(yù)筑拱與軟弱圍巖的相互作用關(guān)系及支護特性,主要工作及結(jié)論如下： 1、針對預(yù)筑拱的合理支護參數(shù),本文根據(jù)荷載—結(jié)構(gòu)模型,基于安全系數(shù)法,分析研究了不同預(yù)筑拱厚度、不同鋼拱架支撐間隔距離以及不同混凝土強度條件下預(yù)筑拱安全系數(shù)的變化情況,為預(yù)筑拱支護參數(shù)的合理選取提供了支持； 2、基于對拱效應(yīng)的數(shù)值計算,通過FLAC3D三維數(shù)值分析,采用地層結(jié)構(gòu)法,根據(jù)地層變形曲線、拱頂上方地層壓力-深度曲線、拱頂上方壓力拱發(fā)展及分布形式,分析了預(yù)筑拱控制預(yù)收斂變形、圍巖收斂變形、應(yīng)力釋放等的特點,計算出預(yù)筑拱作用下隧道開挖過程中拱頂上方坍落拱發(fā)展過程及分布情況,得到了預(yù)筑拱控制軟弱圍巖的變形機理； 3、針對預(yù)筑拱控制軟弱圍巖的變形特性,通過FLAC3D進行大量的數(shù)值分析,得出了不同埋深、不同圍巖條件、不同預(yù)筑拱厚度、不同隧道直徑、不同預(yù)筑拱支護長度等條件下,預(yù)筑拱對于圍巖變形、應(yīng)力釋放及重分布過程、拱頂上方坍落拱的發(fā)展過程等的控制效果；通過引入拱頂上方地層壓力歸一化比值λ,得到了隧道開挖過程中拱頂上方地層壓力的釋放及重分布情況；最終得出了預(yù)筑拱控制圍巖變形的特性； 4、根據(jù)收斂-約束法,基于彈塑性力學(xué)有關(guān)知識,得出了彈性及彈塑性條件下圍巖收斂曲線(圍巖特征曲線),在此基礎(chǔ)上求出了預(yù)筑拱支護下的圍巖收斂曲線；在考慮隧道開挖過程中掌子面附近三維空間效應(yīng)的基礎(chǔ)上,引入圍巖應(yīng)力釋放系數(shù),得出了掌子面掘進過程中預(yù)筑拱與圍巖的相互作用關(guān)系,求出了預(yù)筑拱與圍巖相互作用荷載,并基于安全性得出了預(yù)筑拱混凝土強度與適用埋深的關(guān)系,預(yù)筑拱適用埋深隨圍巖參數(shù)的變化規(guī)律,為預(yù)筑拱支護設(shè)計理論的建立奠定基礎(chǔ)。
[Abstract]:Abstract : The tunnel construction under the geological condition of weak surrounding rock is one of the most important problems in tunnel engineering .

1 . According to the reasonable supporting parameters of pre - built arch , this paper analyzes the changes of pre - built arch safety coefficient under different pre - built arch thickness , different steel arch support spacing distance and different concrete strength under the load - structure model , and provides support for the reasonable selection of pre - built arch support parameters ;


2 . Based on the numerical calculation of arch effect , through FLAC3D numerical analysis , the characteristics of pre - convergence deformation , convergence deformation of surrounding rock , stress release and so on are analyzed according to the formation deformation curve , the formation pressure - depth curve above the arch top , the pressure arch above the dome roof and the distribution form , and the deformation mechanism of the pre - arch control weak surrounding rock is obtained .


3 . According to the deformation characteristics of the weak surrounding rock controlled by the pre - built arch , a lot of numerical analysis is carried out through FLAC3D , and the control effect of the pre - built arch on the deformation of surrounding rock , the stress release and the redistribution process , the development process of the collapse arch above the arch top are obtained under the condition of different burial depth , different surrounding rock conditions , different pre - built arch thickness , different tunnel diameter and different pre - arch support length .
By introducing the normalized ratio 位 of the formation pressure above the dome roof , the release and redistribution of the formation pressure above the arch top during tunnel excavation are obtained .
Finally , the characteristics of the deformation of the surrounding rock of the pre - built arch are obtained .


4 . According to the convergence - constraint method , based on the relevant knowledge of elastic - plastic mechanics , the convergence curve of surrounding rock under elastic and elastic - plastic conditions is obtained ( the characteristic curve of surrounding rock ) , and the convergence curve of surrounding rock under pre - arch support is obtained .
Based on the three - dimensional space effect in the tunnel excavation process , the stress release coefficient of surrounding rock is introduced , the interaction between the pre - built arch and the surrounding rock is obtained through the interaction between the pre - built arch and the surrounding rock , and the relationship between the pre - built arch and the surrounding rock is obtained . Based on the safety , the relationship between the pre - built arch concrete strength and the applicable burial depth is obtained .
【學(xué)位授予單位】：北京交通大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：U451.2;U455.49

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本文編號：1929701