本文選題：新建隧道上穿 + 既有地鐵隧道�。� 參考：《哈爾濱工業(yè)大學(xué)》2017年碩士論文

【摘要】：隨著我國(guó)城市地鐵的大量建設(shè)以及地鐵網(wǎng)絡(luò)的不斷完善,新建隧道上穿既有已運(yùn)營(yíng)的地鐵隧道的工程越來(lái)越多。新建隧道的開(kāi)挖勢(shì)必會(huì)破壞周圍地層平衡應(yīng)力場(chǎng),從而使既有地鐵隧道結(jié)構(gòu)產(chǎn)生附加內(nèi)力和變形,因此如何有效預(yù)測(cè)以及控制新建隧道上穿對(duì)既有地鐵隧道的縱向隆起變形成為了穿越工程中急需解決的難題。為保證既有地鐵的安全運(yùn)營(yíng),本文著重研究新建隧道上穿工程對(duì)既有地鐵隧道的卸荷作用機(jī)理、力學(xué)響應(yīng)規(guī)律以及既有隧道結(jié)構(gòu)隆起的影響因素,并提出相應(yīng)的控制措施及建議。本文的主要研究工作及成果如下:建立了新建隧道上穿對(duì)既有地鐵隧道的卸荷模型,基于Mindlin彈性應(yīng)力解求解了既有地鐵隧道受到的卸荷附加應(yīng)力。通過(guò)求解卸荷附加應(yīng)力系數(shù),系統(tǒng)地分析了上穿卸荷因素對(duì)既有地鐵隧道受到的卸荷作用的影響。研究表明:土體平均泊松比以及新建隧道縱坡對(duì)既有隧道受到的卸荷作用影響不大。針對(duì)新建隧道上穿既有地鐵隧道工程,將既有地鐵隧道視作擱置在利夫金地基模型上的Euler-Bernoulli梁模型,基于“兩階段分析法”思路,提出了一種新建隧道上穿工程對(duì)既有地鐵隧道隆起位移的計(jì)算方法。通過(guò)算例結(jié)果與數(shù)值解的對(duì)比確定了利夫金模型的無(wú)量綱參數(shù),改進(jìn)了傳統(tǒng)兩階段分析法中Winkler模型地基不連續(xù)的缺陷�；谌齻�(gè)已報(bào)道的工程實(shí)例驗(yàn)證了本文計(jì)算方法的有效性,本文方法可快速有效預(yù)測(cè)既有隧道隆起位移。以深圳市地鐵6號(hào)線上穿既有4號(hào)線擬建工程為背景,通過(guò)MIDAS/GTS NX軟件建立了新建隧道上穿既有地鐵隧道的三維有限元模型,重點(diǎn)研究了新建隧道上穿卸荷因素對(duì)既有地鐵隧道縱向隆起變形的影響,并提出了相應(yīng)的抗浮措施及建議。研究表明:既有隧道隆起位移峰值與開(kāi)挖斷面面積近似成正比,工程中應(yīng)考慮隧道施工的時(shí)空效應(yīng),盡量減小一次開(kāi)挖面積及掘進(jìn)距離,及時(shí)施作支護(hù)結(jié)構(gòu);上穿過(guò)程中,隆起值變化較為明顯的階段為穿越前后各1.5倍開(kāi)挖外徑,實(shí)際工程中可考慮在新建隧道內(nèi)部距離既有隧道軸線1.5倍開(kāi)挖外徑的區(qū)域及相應(yīng)的地表區(qū)域采取堆載抗浮措施;增大水平投影夾角可以降低既有隧道的隆起量,當(dāng)水平投影夾角大于45°時(shí),其降低速率變緩;隨夾層土體厚度的增大,既有隧道最大隆起位移逐漸減小,且變化速率變緩,工程中應(yīng)使夾層土體厚度大于1.5倍開(kāi)挖外徑;新建雙線隧道對(duì)既有隧道的隆起影響可看作兩個(gè)單線隧道的疊加,隨著雙線隧道軸線間距變大,既有隧道的隆起峰值變小,實(shí)際工程中應(yīng)盡量增大雙線隧道間的距離,消除隧道間的疊加效應(yīng)。
[Abstract]:With the large number of urban subway construction and the continuous improvement of subway network, there are more and more new tunnels passing through the existing subway tunnels. The excavation of the new tunnel will inevitably destroy the equilibrium stress field of the surrounding strata, thus causing additional internal force and deformation to the existing subway tunnel structure. Therefore, how to effectively predict and control the longitudinal uplift deformation of the existing subway tunnel through the new tunnel has become a difficult problem that needs to be solved in the crossing engineering. In order to ensure the safe operation of the existing subway, the mechanism of unloading, the law of mechanical response and the factors affecting the uplift of the existing tunnel structure are studied in this paper. And put forward the corresponding control measures and suggestions. The main work and results of this paper are as follows: the unloading model of the existing subway tunnel is established, and the additional unloading stress of the existing subway tunnel is solved based on the Mindlin elastic stress solution. By solving the additional stress coefficient of unloading, the influence of unloading factors on the unloading of existing subway tunnels is analyzed systematically. The results show that the average Poisson's ratio of soil and the longitudinal slope of new tunnel have little effect on the unloading of existing tunnel. Aiming at the project of passing through the existing subway tunnel, the existing subway tunnel is regarded as Euler-Bernoulli beam model shelved on the foundation model of Lifkin, based on the idea of "two-stage analysis". In this paper, a method for calculating the uplift displacement of existing subway tunnel is presented. The dimensionless parameters of the Lifkin model are determined by comparing the numerical results with the numerical results, and the defects of the Winkler model foundation discontinuity in the traditional two-stage analysis method are improved. Based on three reported engineering examples, the effectiveness of the proposed method is verified. The proposed method can be used to predict the uplift displacement of existing tunnels quickly and effectively. Based on the proposed construction of Shenzhen Metro Line 6 through existing Line 4, the 3D finite element model of new tunnel through existing subway tunnel is established by Midas / GTS NX software. The influence of unloading factors on the longitudinal uplift deformation of existing subway tunnel is studied, and the corresponding anti-floating measures and suggestions are put forward. The research shows that the peak displacement of the existing tunnel uplift is approximately proportional to the area of the section of the excavation. The space-time effect of tunnel construction should be taken into account in the project, the area of primary excavation and the distance of excavation should be reduced as far as possible, and the supporting structure should be constructed in time. The obvious change of uplift value is 1.5 times outside diameter of excavation before and after crossing. In actual engineering, the anti-floating measures can be taken in the area with 1.5 times outer diameter of existing tunnel axis and the corresponding surface area. Increasing the angle of horizontal projection can reduce the uplift of the existing tunnel. When the angle of horizontal projection is greater than 45 擄, the decrease rate of the tunnel becomes slower, and the maximum uplift displacement of the existing tunnel decreases gradually with the increase of the thickness of the intercalated soil, and the change rate of the tunnel becomes slower. In engineering, the thickness of interlayer soil should be greater than 1.5 times of the outer diameter of excavation, the influence of the new double-line tunnel on the uplift of the existing tunnel can be regarded as the superposition of two single-line tunnels, and the peak value of the uplift of the existing tunnel becomes smaller with the increase of the distance between the axes of the two-line tunnel. In practical engineering, the distance between two-line tunnels should be increased as far as possible to eliminate the superposition effect between tunnels.
【學(xué)位授予單位】：哈爾濱工業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：U456.3

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本文編號(hào)：2107531