長江近入海口復(fù)雜地質(zhì)條件下隧道工程風險評價
發(fā)布時間：2018-08-07 18:11
【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。但是隧道工程因為所處地質(zhì)條件的不明確和隱蔽性,與之而來的問題就是建設(shè)過程中存在很多風險。這不僅會造成生命和財產(chǎn)的損失,還會造成一定的社會影響。在隧道項目的規(guī)劃和實施階段,利用合適的方法對隧道風險分析,不僅可以確定工程建設(shè)的風險程度,還可以預(yù)判可能產(chǎn)生的風險事故,從而方便我們采取一定的風險控制措施,從而有效減少風險事故造成的損失。本文針對長江近入�？趶�(fù)雜地質(zhì)條件下的隧道工程進行風險評價。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,通過風險因素的分析與穩(wěn)定性風險分析,提出符合工程實際的方法進行風險評價。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險因素進行分析。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,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,并對其進行風險分析,得出結(jié)論認為隧道埋置深度的增加有利于穩(wěn)定,但是當隧道處于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)合工程實際,提出分區(qū)段對隧道風險評價。按地質(zhì)條件的變化對隧道進行區(qū)段劃分,建立分區(qū)風險評價體系。采用綜合風險指數(shù)評價方法對隧道風險評價,并對各區(qū)段風險因素的重要程度分析。通過本文提出的風險評價體系進行計算,最后得出D段和E段處于中等風險等級,尤其是E段風險指數(shù)接近較高風險等級。另外B段和C段處于風險較低等級,A段風險指數(shù)最小。分析各段所處的風險等級,提出切合工程實際的防滲,防沼氣等風險控制措施,目的在于降低風險,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.
【學位授予單位】：南京大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：U452.11
本文編號：2170902
[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.
【學位授予單位】：南京大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：U452.11
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