【摘要】：近年來,我國隧道及地下工程建設(shè)數(shù)量不斷上升,工程建設(shè)的難度持續(xù)增加,規(guī)模也越來越龐大。但是隧道工程因?yàn)樗幍刭|(zhì)條件的不明確和隱蔽性,與之而來的問題就是建設(shè)過程中存在很多風(fēng)險(xiǎn)。這不僅會造成生命和財(cái)產(chǎn)的損失,還會造成一定的社會影響。在隧道項(xiàng)目的規(guī)劃和實(shí)施階段,利用合適的方法對隧道風(fēng)險(xiǎn)分析,不僅可以確定工程建設(shè)的風(fēng)險(xiǎn)程度,還可以預(yù)判可能產(chǎn)生的風(fēng)險(xiǎn)事故,從而方便我們采取一定的風(fēng)險(xiǎn)控制措施,從而有效減少風(fēng)險(xiǎn)事故造成的損失。本文針對長江近入�？趶�(fù)雜地質(zhì)條件下的隧道工程進(jìn)行風(fēng)險(xiǎn)評價。主要以常熟電廠輸水盾構(gòu)隧道為例,針對其復(fù)雜的地質(zhì)水文條件,通過風(fēng)險(xiǎn)因素的分析與穩(wěn)定性風(fēng)險(xiǎn)分析,提出符合工程實(shí)際的方法進(jìn)行風(fēng)險(xiǎn)評價。主要研究內(nèi)容及成果如下：(1)結(jié)合工程區(qū)地質(zhì)條件和水文條件,分別從隧道特征、管片特征、圍巖特征,對常熟電廠輸水隧道風(fēng)險(xiǎn)因素進(jìn)行分析。按照已有的理論,對隧道建設(shè)過程中各方面的穩(wěn)定性判斷,并得到了一些結(jié)論：底部承壓含水層水壓較大,如果防水措施不當(dāng),在施工過程中承壓含水層會造成流土等地質(zhì)災(zāi)害；而且第⑤層土含有沼氣、朽木和腐殖質(zhì),會對施工過程產(chǎn)生影響。(2)工程場區(qū)處于長江與徐六涇河交界處,河流作用會對埋置于河床底部的隧道產(chǎn)生影響。因受到潮流和徑流的雙重作用,通過分析河床在落潮期間處于沖刷狀態(tài)。但落潮流所處長江主泓位置位于長江深槽處,距離隧道仍有800m左右,而且深槽坡度只有10%；加之近年來,長江中下游地區(qū)水庫和護(hù)岸工程建設(shè),使得徐六涇河段處于相對穩(wěn)定的狀態(tài),所以在隧道使用期內(nèi)河勢的變化并不會對隧道穩(wěn)定性產(chǎn)生影響。(3)通過數(shù)值模擬的方式分析了隧道開挖對周圍土體的擾動,并對其進(jìn)行風(fēng)險(xiǎn)分析,得出結(jié)論認(rèn)為隧道埋置深度的增加有利于穩(wěn)定,但是當(dāng)隧道處于④⑤層土中時,處于最不利情況。還通過建立涌水模型,利用蒙特卡羅來模擬分析隧道涌水與潮位變化的關(guān)系,得出了隧道涌水主要受底部承壓含水層控制,需要在施工過程中做好防水措施。(4)結(jié)合工程實(shí)際,提出分區(qū)段對隧道風(fēng)險(xiǎn)評價。按地質(zhì)條件的變化對隧道進(jìn)行區(qū)段劃分,建立分區(qū)風(fēng)險(xiǎn)評價體系。采用綜合風(fēng)險(xiǎn)指數(shù)評價方法對隧道風(fēng)險(xiǎn)評價,并對各區(qū)段風(fēng)險(xiǎn)因素的重要程度分析。通過本文提出的風(fēng)險(xiǎn)評價體系進(jìn)行計(jì)算,最后得出D段和E段處于中等風(fēng)險(xiǎn)等級,尤其是E段風(fēng)險(xiǎn)指數(shù)接近較高風(fēng)險(xiǎn)等級。另外B段和C段處于風(fēng)險(xiǎn)較低等級,A段風(fēng)險(xiǎn)指數(shù)最小。分析各段所處的風(fēng)險(xiǎn)等級,提出切合工程實(shí)際的防滲,防沼氣等風(fēng)險(xiǎn)控制措施,目的在于降低風(fēng)險(xiǎn),減少損失。
[Abstract]:In recent years, the quantity of tunnel and underground engineering in our country has been increasing, and the difficulty and scale of construction have been increasing. However, due to the uncertainty and concealment of the geological conditions, the problem of tunnel engineering is that there are many risks in the process of construction. This will not only cause loss of life and property, but also a certain social impact. In the planning and implementation stage of the tunnel project, using the appropriate method to analyze the tunnel risk can not only determine the risk degree of the project construction, but also predict the possible risk accident. Therefore, it is convenient for us to take certain risk control measures, thus effectively reducing the loss caused by risk accidents. This paper evaluates the risk of tunnel engineering near the estuary of Yangtze River. Taking the shield tunnel of Changshu Power Plant as an example, according to the complex geological and hydrological conditions, the risk assessment method is put forward by analyzing the risk factors and stability risk. The main research contents and results are as follows: (1) combined with the geological and hydrological conditions of the engineering area, the risk factors of the water conveyance tunnel in Changshu Power Plant are analyzed from the tunnel characteristics, segment characteristics and surrounding rock characteristics respectively. According to the existing theory, the stability of all aspects in the tunnel construction is judged, and some conclusions are drawn: the water pressure of the bottom confined aquifer is high, if the waterproof measures are not appropriate, During the construction process, the confined aquifer will cause geological hazards such as flowing soil, and the fifth layer of soil contains biogas, dead wood and humus, which will have an impact on the construction process. (2) the engineering site is located at the junction of the Yangtze River and the Xuliujing River. The action of the river affects the tunnel buried at the bottom of the river bed. Because of the dual effect of tidal current and runoff, the river bed is scoured during the period of falling tide. However, the main Yangtze River current is located at the deep trough of the Yangtze River, which is still about 800 meters from the tunnel, and the slope of the deep channel is only 10. In addition, in recent years, reservoirs and bank protection projects have been built in the middle and lower reaches of the Yangtze River. The Xuliujing River section is in a relatively stable state, so the variation of the river potential in the tunnel will not affect the tunnel stability. (3) the disturbance of the tunnel excavation to the surrounding soil is analyzed by numerical simulation. It is concluded that the increase of the buried depth of the tunnel is beneficial to stability, but the tunnel is in the most disadvantageous situation when it is in 45 layers of soil. Through the establishment of water gushing model and the simulation analysis of the relationship between tunnel gushing and tidal level change by Monte Carlo, it is concluded that tunnel gushing is mainly controlled by the bottom confined aquifer, which requires good waterproof measures in the construction process. (4) combined with the engineering practice, it is necessary to do a good job in waterproof measures. The risk assessment of tunnel is proposed. According to the change of geological conditions, the section of tunnel is divided and the risk assessment system is established. The comprehensive risk index evaluation method is used to evaluate the tunnel risk, and the importance of risk factors in each section is analyzed. Through the calculation of the risk evaluation system proposed in this paper, it is concluded that D and E are in the middle risk grade, especially the risk index of E is close to the higher risk grade. In addition, B and C are at the lowest risk level and A risk index is the lowest. This paper analyzes the risk grade in each section, and puts forward some risk control measures, such as seepage control and biogas control, which are suitable for engineering practice, in order to reduce the risk and reduce the loss.
【學(xué)位授予單位】：南京大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：U452.11

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