本文關(guān)鍵詞： 既有隧道 強(qiáng)度折減 安全系數(shù) 破壞機(jī)理 劣化　出處：《西南交通大學(xué)》2014年碩士論文　論文類型：學(xué)位論文

【摘要】：本文將有限元強(qiáng)度折減法引入到既有隧道安全度的研究中,并以安全系數(shù)作為安全度的判斷標(biāo)準(zhǔn),在均一地層下建立地層—荷載結(jié)構(gòu)模型,對(duì)隧道的支護(hù)力學(xué)行為、隧道基于不同埋深和不同洞型的破壞機(jī)理、既有隧道在圍巖劣化和襯砌劣化時(shí)的安全度、既有隧道在二次襯砌局部厚度不足時(shí)的安全度進(jìn)行了計(jì)算分析。本文的主要結(jié)論如下：(1)利用有限元差分軟件FLAC3D,基于強(qiáng)度折減法,通過(guò)隧道開(kāi)挖后釋放荷載的控制來(lái)等效模擬隧道的支護(hù)時(shí)機(jī)效應(yīng),計(jì)算分析了隧道的支護(hù)力學(xué)行為,計(jì)算結(jié)果表明,支護(hù)時(shí)機(jī)對(duì)隧道最終的安全系數(shù)影響很小,為既有隧道安全評(píng)價(jià)的數(shù)值模擬提供計(jì)算依據(jù)。(2)通過(guò)強(qiáng)度折減法,對(duì)不同埋深和不同洞型隧道的破壞機(jī)理進(jìn)行研究,為既有隧道的破壞機(jī)理解析提供參考。計(jì)算分析表明,隧道隨著埋深的增加,安全系數(shù)呈現(xiàn)先增加、后減小的趨勢(shì)。對(duì)于不同洞型,矩形洞室破壞形式不受埋深影響,均從洞室頂部破壞；直墻拱隧洞在淺埋時(shí)拱頂首先破壞,深埋時(shí)墻腳首先破壞；圓形隧洞與馬蹄形隧洞的破壞機(jī)理相似,淺埋時(shí)拱頂首先破壞,深埋時(shí)邊墻首先破壞。4種斷面形式中圓形斷面最為安全,馬蹄形次之,矩形最不安全。(3)既有隧道產(chǎn)生圍巖和襯砌的全部劣化時(shí),隧道的安全系數(shù)隨著劣化程度的增加而減小。圍巖不同深度劣化時(shí),當(dāng)劣化深度在lm-2m,3m-4m過(guò)程中安全系數(shù)減小較多；不同部位圍巖局部劣化時(shí),仰拱處最為不利。初支全部劣化時(shí),劣化前期安全系數(shù)降低較快；初支局部劣化時(shí),墻腳部位劣化最為不利,邊墻和仰拱次之。二襯全部劣化時(shí),隨著劣化程度的增加,安全系數(shù)減小較快；二襯局部劣化時(shí),拱頂和拱腰局部劣化時(shí)最為不利。二襯局部厚度不足時(shí),隨著二襯厚度的減小,安全系數(shù)不斷減小,其中厚度不足對(duì)拱頂和邊墻部位最為不利。
[Abstract]:In this paper, the finite element strength reduction method is introduced into the study of the safety degree of the existing tunnel, and the safety factor is taken as the criterion of safety degree, and the stratigraph-load structure model is established under the uniform stratum. For the tunnel supporting mechanics behavior, the tunnel based on different buried depth and different hole type failure mechanism, the existing tunnel in the surrounding rock deterioration and lining deterioration safety degree. The safety degree of the existing tunnel is calculated and analyzed when the local thickness of the secondary lining is insufficient. The main conclusions of this paper are as follows: (1) based on the strength reduction method, the finite element difference software FLAC3D is used. Through the control of the release load after the tunnel excavation, equivalent simulation of the tunnel support timing effect, calculated and analyzed the tunnel supporting mechanical behavior, the results show that the supporting time has little effect on the tunnel ultimate safety factor. The failure mechanism of tunnel with different buried depth and different tunnel type is studied by strength reduction method. It provides a reference for the analysis of the failure mechanism of the existing tunnel. The calculation and analysis show that the safety factor of the tunnel increases first and then decreases with the increase of the buried depth. The failure forms of rectangular caverns are not affected by the depth of burying, and are destroyed from the top of the cavern. When the tunnel is shallow buried, the arch roof is destroyed first, and the foot of the wall is destroyed first when buried deeply. The failure mechanism of circular tunnel is similar to that of horseshoe tunnel. The arch top is first destroyed when shallow is buried, and the circular section is the safest in deep burying, and the horseshoe is the second. The safety coefficient of the tunnel decreases with the increase of the deterioration degree when the tunnel has all the deterioration of surrounding rock and lining. When the surrounding rock is deteriorating at different depth, the depth of deterioration is in lm-2m. The safety factor decreases more in 3m-4m process. When the local deterioration of surrounding rock is different, the inverted arch is the most disadvantageous. When all the initial branches are degraded, the safety coefficient of the early stage of deterioration decreases rapidly. In the local deterioration of the first branch, the deterioration of the foot of the wall is the most unfavorable, followed by the side wall and the inverted arch. When the second lining is all degraded, the safety factor decreases faster with the increase of the deterioration degree. When the local thickness of the second liner is insufficient, the safety factor decreases with the decrease of the thickness of the second liner. The lack of thickness is most disadvantageous to the arch and the side wall.
【學(xué)位授予單位】：西南交通大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：U457.2

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本文編號(hào)：1482010