本文選題：小凈距隧道 + 有限元法��； 參考：《蘭州交通大學(xué)》2014年碩士論文

【摘要】：本文依托蘭州樞紐新建的北環(huán)隧道上穿既有紅山頂隧道為工程參考背景，兩隧道交叉斷面處最小凈距1.365m，交叉角度為43.287度。新建隧道爆破開挖施工產(chǎn)生的爆炸沖擊波會對圍巖及既有隧道襯砌結(jié)構(gòu)產(chǎn)生振動影響造成一定的不穩(wěn)定性。本文運用動力有限元原理，采用LS-DYNA3D有限元分析程序?qū)π陆ㄋ淼辣崎_挖產(chǎn)生的沖擊波對既有隧道的影響進行數(shù)值模擬分析，得到了爆炸沖擊波在圍巖與既有隧道襯砌結(jié)構(gòu)上的傳播規(guī)律，也為數(shù)值計算分析和實際施工提供了一定的參考依據(jù)。研究方面如下: ⑴首先對空間交叉小凈距隧道在爆破開挖施工過程中存在的問題進行了概述，并針對個別問題提出本文的研究方向及目的；其次詳細的分析總結(jié)了國內(nèi)外近10年尤其是我國學(xué)者與工程技術(shù)人員在空間交叉隧道和隧道爆破開挖領(lǐng)域的理論計算、數(shù)值模擬成果和工程實踐積累的經(jīng)驗。 ⑵就巖石爆破理論闡述了巖石破壞機理與爆破地震波的產(chǎn)生與傳播方式，并就國內(nèi)外的爆破振動影響的控制標準進行了對比分析；而且還針對LS-DYAN3D動力有限元分析程序在爆炸沖擊數(shù)值計算領(lǐng)域的應(yīng)用進行了詳細闡述。 ⑶從現(xiàn)場實際爆破施工與實際控制標準出發(fā)分析了工況1在交叉點斷面處爆破開挖對既有隧道襯砌結(jié)構(gòu)的振動影響，對既有隧道襯砌結(jié)構(gòu)的分析從3個要素著手：①分析了典型位置處如拱頂振速的變化規(guī)律，以此為依據(jù)判斷分析出既有隧道受爆破振動較危險的區(qū)域；②就爆破沖擊產(chǎn)生的應(yīng)力波既有隧道二次襯砌應(yīng)力分布形式與時間歷程進行了分析，提出了受爆破沖擊敏感度較高的區(qū)域位置；③從即有隧道二次襯砌拉伸應(yīng)力破壞角度出發(fā)分析既有隧道斷面受爆破沖擊波的影響沿拱頂?shù)焦把窖龉疤幚鞈?yīng)力的傳播變化規(guī)律。 ⑷對不同凈距條件下既有隧道二次襯砌結(jié)構(gòu)受爆破沖擊的影響進行了分析，并得出了振速與應(yīng)力隨凈距的變化規(guī)律，得出了臺階法爆破施工時的臨界凈距，還觀測了爆炸沖擊波由爆孔經(jīng)過圍巖到既有隧道襯砌隨時間的變化圖示。 ⑸在不同圍巖下既有隧道二次襯砌振速與應(yīng)力的變化規(guī)律進行了分析，并從實際施工的角度分析了各工況下對既有隧道造成的不安全性，，同時分析了距交叉點斷面不同間距下爆破掌子面爆破時既有隧道迎爆面沿二次襯砌的移動規(guī)律。
[Abstract]:Based on the project background of the new North Ring Tunnel in Lanzhou hub, the minimum net distance at the cross section of the two tunnels is 1.365 m and the cross angle is 43.287 degrees.The blast wave produced by blasting excavation of new tunnel will cause instability to the surrounding rock and the existing tunnel lining structure.In this paper, the influence of blast wave on the existing tunnel caused by blasting excavation in a new tunnel is numerically simulated and analyzed by using the dynamic finite element principle and LS-DYNA3D finite element analysis program.The propagation law of blast wave in surrounding rock and lining structure of existing tunnel is obtained. It also provides a certain reference for numerical calculation analysis and actual construction.The research areas are as follows:Firstly, the problems existing in the construction of space crossing small clear distance tunnel during blasting excavation are summarized, and the research direction and purpose of this paper are put forward.Secondly, the theoretical calculation, numerical simulation results and engineering experience accumulated in the field of space cross tunnel and tunnel blasting excavation in recent 10 years, especially in our country, especially in China, are analyzed and summarized in detail.(2) based on rock blasting theory, the rock failure mechanism and blasting seismic wave generation and propagation mode are expounded, and the control standards of blasting vibration at home and abroad are compared and analyzed.Moreover, the application of LS-DYAN3D dynamic finite element analysis program in the field of numerical calculation of explosion shock is described in detail.3. Based on the actual blasting construction and actual control standard, the vibration effect of blasting excavation on existing tunnel lining structure at cross section is analyzed.Based on the analysis of existing tunnel lining structure, the variation law of vibration velocity at typical locations such as arch roof is analyzed from three elements: 1. Based on this analysis, the dangerous region of existing tunnel subjected to blasting vibration is analyzed.(2) the stress distribution form and time history of the secondary lining of the existing tunnel caused by blasting impact are analyzed, and the location of the region with high sensitivity to blasting impact is proposed.(3) from the angle of the secondary lining tensile stress failure of the tunnel, the propagation and variation of the tensile stress along the arch top to the arch waist to the inverted arch are analyzed by the influence of blasting shock wave on the existing tunnel section.4. The influence of blasting shock on the secondary lining structure of existing tunnel under different net distance is analyzed, and the variation law of vibration velocity and stress with net distance is obtained, and the critical net distance during step blasting construction is obtained.The time variation of blast wave from blasting hole through surrounding rock to existing tunnel lining is also observed.5. The variation law of vibration velocity and stress of secondary lining of existing tunnel under different surrounding rock is analyzed, and the insecurity of existing tunnel under different working conditions is analyzed from the point of view of actual construction.At the same time, the moving law of the blasting face along the secondary lining of the existing tunnel is analyzed under the different spacing between the cross section and the blasting face.
【學(xué)位授予單位】：蘭州交通大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：U455.6

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