本文關(guān)鍵詞： 淺埋 偏壓 大跨度 三臺(tái)階七步工法 數(shù)值模擬　出處：《中國(guó)地質(zhì)大學(xué)(北京)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：當(dāng)前常用于淺埋偏壓大跨度隧道開(kāi)挖方法主要有全斷面法、臺(tái)階法、環(huán)形開(kāi)挖預(yù)留核心土法、CD工法、CRD工法、單側(cè)壁導(dǎo)坑法、雙側(cè)壁導(dǎo)坑法等,各類施工工法有其自身可以施工的工程地質(zhì)狀況。大跨度隧道由于斷面較大,洞內(nèi)巖體開(kāi)挖后圍巖有較大的卸荷和變形空間,局部巖體可能出現(xiàn)變形過(guò)大而發(fā)生破壞,采用合理的施工工法在開(kāi)挖過(guò)程中對(duì)圍巖的卸荷和變形加以控制,是保證施工順利進(jìn)行的有效手段。采用不同的施工工法,開(kāi)挖斷面大小和對(duì)圍巖的擾動(dòng)程度不同,圍巖的變形和應(yīng)力釋放情況也不同,再者,不同的施工工法所需要的材料成本、人工成本、機(jī)械成本和時(shí)間成本相差比較大,這和施工企業(yè)的經(jīng)濟(jì)效益密切相關(guān)。本文以貴陽(yáng)市黔春大道七沖村二號(hào)隧道為研究對(duì)象,該隧道屬于典型的淺埋偏壓大跨度隧道,通過(guò)在現(xiàn)場(chǎng)進(jìn)行監(jiān)測(cè)試驗(yàn)和MIDAS-GTS有限元軟件數(shù)值模擬相結(jié)合的方法,對(duì)本隧道開(kāi)挖過(guò)程中所采用的工法進(jìn)行研究。具體研究?jī)?nèi)容如下:(1)按試驗(yàn)要求在七沖村二號(hào)隧道開(kāi)挖過(guò)程中對(duì)選定三臺(tái)階七步工法開(kāi)挖斷面進(jìn)行了圍巖與初襯間土壓力、初襯與二襯間壓力、圍巖位移、鋼拱架應(yīng)變和二襯應(yīng)變的監(jiān)測(cè)工作,并對(duì)監(jiān)測(cè)數(shù)據(jù)進(jìn)行整理分析,得出實(shí)際開(kāi)挖過(guò)程中圍巖和支護(hù)結(jié)構(gòu)的受力特性,說(shuō)明三臺(tái)階七步工法可以適用于淺埋偏壓大跨度隧道的開(kāi)挖。(2)建立實(shí)際施工采用的三臺(tái)階七步工法數(shù)值模擬模型,對(duì)開(kāi)挖狀態(tài)下的圍巖塑性區(qū)、圍巖應(yīng)力分布、圍巖位移、初襯應(yīng)力和二襯應(yīng)力進(jìn)行研究,得出圍巖和支護(hù)結(jié)構(gòu)的應(yīng)力、應(yīng)變的特點(diǎn)。將三臺(tái)階七步法開(kāi)挖模型計(jì)算結(jié)果進(jìn)行提取并與現(xiàn)場(chǎng)監(jiān)測(cè)所得數(shù)據(jù)進(jìn)行對(duì)比分析,證明該數(shù)值模型可以準(zhǔn)確反應(yīng)客觀施工過(guò)程。(3)對(duì)選定隧道YK2+760斷面進(jìn)行三臺(tái)階七步法、單側(cè)壁導(dǎo)坑法和雙側(cè)壁導(dǎo)坑法開(kāi)挖進(jìn)行數(shù)值模擬,對(duì)三種開(kāi)挖工法下的圍巖塑性區(qū)、圍巖應(yīng)力分布、圍巖豎向位移和水平位移、初襯應(yīng)力和二襯應(yīng)力進(jìn)行對(duì)比分析,得出三種施工工法下各自圍巖和支護(hù)結(jié)構(gòu)的應(yīng)力、應(yīng)變特點(diǎn),找出各應(yīng)力、應(yīng)變指標(biāo)之間的差異大小,說(shuō)明三種工法均可滿足現(xiàn)場(chǎng)施工需要,施工過(guò)程中可以根據(jù)具體工程地質(zhì)條件需要,選擇合適的開(kāi)挖工法,以達(dá)到指導(dǎo)施工的目的。
[Abstract]:At present, the main excavation methods are full section method, step method, ring excavation reserved core earth method and CRD method, single side wall method, double side wall method and so on. All kinds of construction methods have their own engineering geological conditions. Due to the large section of large-span tunnel, the surrounding rock mass in the tunnel has larger unloading and deformation space after excavation. The local rock mass may be deformed and destroyed, so the unloading and deformation of surrounding rock can be controlled by reasonable construction method. Using different construction methods, the excavation section size and disturbance degree of surrounding rock are different, and the deformation and stress release of surrounding rock are also different. The material cost, labor cost, mechanical cost and time cost of different construction methods are quite different. This is closely related to the economic benefits of construction enterprises. This paper takes Qianchun Avenue Qichongcun No.2 Tunnel in Guiyang as the research object. The tunnel belongs to the typical shallow buried bias pressure long span tunnel. The method of combining the monitoring test with the numerical simulation of MIDAS-GTS finite element software on the spot is presented. In this paper, the working methods used in the excavation of this tunnel are studied. The specific research contents are as follows: 1). According to the test requirements, the earth pressure between surrounding rock and initial lining was carried out in the excavation process of Qichongcun No. 2 tunnel. Monitoring of initial and second liner pressure, surrounding rock displacement, steel arch frame strain and second lining strain, and analysis of monitoring data, the stress characteristics of surrounding rock and supporting structure during actual excavation are obtained. It shows that the three-step and seven-step method can be applied to the excavation of shallow buried biasing large-span tunnel. The numerical simulation model of the three-step seven-step construction method used in actual construction is established, and the plastic zone of surrounding rock under excavation state can be obtained. The stress distribution of surrounding rock, displacement of surrounding rock, initial lining stress and second lining stress are studied, and the stress of surrounding rock and supporting structure is obtained. The characteristics of strain. The calculation results of three-step and seven-step excavation model are extracted and compared with the field monitoring data. It is proved that the numerical model can accurately reflect the objective construction process.) the excavation of selected tunnel section YK2 760 can be numerically simulated by three-step seven-step method single-side wall method and double-side wall method. The plastic zone of surrounding rock, the stress distribution of surrounding rock, the vertical displacement and horizontal displacement of surrounding rock, the initial lining stress and the second lining stress under three excavation methods are compared and analyzed. The stress and strain characteristics of each surrounding rock and supporting structure under three construction methods are obtained, and the difference between the stress and strain indexes is found out, which indicates that the three construction methods can meet the site construction needs. In order to guide the construction, the appropriate excavation method can be selected according to the specific engineering geological conditions in the construction process.
【學(xué)位授予單位】：中國(guó)地質(zhì)大學(xué)(北京)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：U455.4
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本文編號(hào)：1492658