隧道塌方總結(jié)

1、隧道塌方總結(jié)1 （共6頁）-本頁僅作為文檔封面，使用時請直接刪除即可-內(nèi)頁可以根據(jù)需求調(diào)整合適字體及大小-隧道圍巖大變形研究分析due to the influence of natural geological conditions, collapse accident often bring enormous damage to the tunnel construction in the large section tunnel excavation of road (or railroad) construction.engineering equipment and the safe

2、ty of personnel are seriously threatened by the collapse of tunnel which has the character of high incidence and high risk.1、primary influence factors and types of tunnel collapseThe main factors of tunnel collapseThere are many influence factors in tunnel collapse, generally can be divided into ext

3、ernal and internal factors, internal factors are mainly refer to the engineering geological and hydrogeological conditions, external factors are mainly refer to improper design and construction.unfavorable geological conditionsunfavorable geological mainly includes the weathered metamorphic rock, fr

4、actured rock mass and rock pile area, fault, karst cave, landslide, mudslide, swelling strata, the tunnel encountered to those geological condition,some slight negligence may lead to the collapse of tunnel.underground waterGroundwater is one of the important factors influencing the stability of surr

5、ounding rock. it not only reduces the strength of rock which has high softening coefficient, and also reduces the shear strength of structure plane.geostress geostress mainly includes the bias, plasticity, landslides and high ground stress area, etc.,there are many instances of collapse happened in

6、the entrance zone of the tunnel were caused by bias and landslide,extrusion destruction of tunnel is often caused by plastic pressure,and rock burst often occured in high ground stress area, etc.mproper design and construction.At present, New Austrian Tunnelling Method is used to design and construc

7、tion in most of the tunnel, However, the deviation understanding of the concept and connotation of the principle led to many failure in engineering.collapse of tunnel is induced by many factors and the mechanism is of more complex, therefore, improper treatment measures for the complex geological du

8、ring the construction will easily cause the occurrence of collapse disasters.analysis of collapse typesthere are many types of partitioning method, generally based on the cause of collapse, form, scale, mechanism, etc. it mainly divides into the following five kinds of forms.Partial collapse : Mainl

9、y happened in large blocky rock mass, the rock mass is cutted by structure surface and formed into different shapes of unstable structure. After cavern excavation, the friction direction of unstable structure surface slide and collapse occured.Arch collapse : Typically occur in layered rock mass or

10、broken rock mass, it has two kinds, one kind is in the range of the pit, only occur in the arch department; Another kind is expanding arch collapse, including wall collapse.Deformed collapse : collapse induced by special geological conditions (caves, sinkhole, etc.), shallow buried and bias.swelling

11、 rock tunnel collapse : Due to high inflation pressure acts on the shotcrete support; The expansion of the rock body reduces the friction and shear strength; High water pressure accumulation。Large deformation of tunnel the rock burst : surrounding rock large deformation problem of deep buried,long-l

12、arge tunnels and underground engineering under high geostress condition has become a problem in underground engineering and become a major issue to be solved.2、deformation analysis for surrounding rock of tunnelsWith the rapid development of tunnel and underground engineering, the characteristic of

13、its long- scale-deep are increasingly obvious, and it is prone to geological disasters , such as large deformation of surrounding rock in certain geological and environmental geological conditions. Based on a lot of literature retrieval, it is obviously that surrounding rock large deformation is a k

14、ind of great hazardous geology casualty of tunnel and underground engineering.current research of large deformation of Tunnel surrounding rockthough a lot of domestic and foreign scholars have done a lot of exploration efforts, due to the large deformation theory research is not mature, as well as t

15、he complexity of on-site geological rock mass condition, the current research work is mainly manifested in the following aspects.The concept for large deformationthere is no form a consistent and clear definition About the large deformation of surrounding rock, Some scholars according to whether the

16、 deformation of surrounding rock is within the reserved deformation of primary support to define it. Also some scholars think it shouldnt be defined by the absolute value of the deformation which is the external performance of large deformation problem. It should be defined by the essence that the s

17、urrounding rock occurs shear deformation , deflection , rupture and failure under the shear stress, and causes the rock mass squash the underground cavity.analysis of the soft rockso far, Rock engineering community has been unable toreach a consensus on the concept of soft rock, the definition of so

18、ft rock is more than a definition of soft rock of ISRM (international society for rock mechanics, 1990 , 1993) is refers to the uniaxial compressive strength of rock was 25 mpa; In 1984 coal mine term discussion (kunming) , soft rock is defined as low strength, high porosity ,poor cementation and af

19、fected by structural plane cutting and weathering or contains a lot of expansive clay minerals and loose, soft rock (body); And some scholars also divide it into geological soft rock and engineering soft rock and so on.mechanism of Large deformationPeople generally divide it into two types base on t

20、he formation mechanism of the surrounding rock large deformation. The first type is caused when redistribution stress exceeds surrounding rocks strength after tunnel excavation, which makes the surrounding rock be plasticity. the other type is caused when certain minerals in the rock react with wate

21、r and inflation. swelling mineral and water are significant for the expansion deformation.type and mechanism of Large deformation of tunnel surrounding rockTunnel surrounding rock large deformation can be defined as: a kind of plastic deformation and failure with progressive and obvious time effect

22、of tunnel and underground engineering surrounding rock, it is different from brittle failure of rock burst and distinguish it from collapse and slide, etc, which are caused by the rocks structure plane of surrounding rock loose zone.the type of Large deformation of tunnel surrounding rockAccording t

23、o the analysis of typical examples and the research on mechanism of large deformation, classification on the large deformation was carried out base on different controlled conditions: controlled by lithology of surrounding rock , controlled by the structure of surrounding rock and affected by artifi

24、cial excavation disturbance.在公路（或鐵路）隧道大斷面開挖施工中，由于自然地質(zhì)條件、施工等的影響， 常會發(fā)生塌方事故，給隧道施工帶來極大危害。塌方以其高發(fā)性、高危性嚴(yán)重威 脅著工程設(shè)備和人員安全。本報告從塌方的類型、塌方的影響因素進(jìn)行了總 結(jié)，并對隧道中的大變形進(jìn)行了一定的介紹。1、隧道塌方類型及塌方主要影響因素隧道塌方主要影響因素影響隧道塌方的因素很多，大體上可分為內(nèi)因和外因，內(nèi)因主要是指工程 地質(zhì)和水文地質(zhì)條件，外因主要是指設(shè)計和施工不當(dāng)。1）不良地質(zhì)條件不良地質(zhì)主要包括風(fēng)化變質(zhì)巖體、裂隙發(fā)育巖體、崩塌巖堆地區(qū)、斷層 帶、溶洞、滑坡、泥石流、膨脹性地層等，當(dāng)隧道

25、從這些巖體中通過時，如稍有疏 忽,就可能發(fā)生大塌方。2）地下水地下水是影響圍巖穩(wěn)定的重要因素之一。這不但能使巖石強度降低，特別 是軟化系數(shù)較大的巖石，而且使結(jié)構(gòu)面的抗剪強度減小。對于斷層，地下水影響更 大，一般張性斷層是儲水結(jié)構(gòu)，壓性斷層帶中斷層糜棱巖是隔水的，而另一側(cè)的破 碎帶為含水的，當(dāng)揭穿斷層后，便時常發(fā)生突發(fā)性涌水導(dǎo)致塌方。3）地壓地壓主要包括偏壓、塑性地壓、滑坡及高地應(yīng)力區(qū)等 ，偏壓和滑坡在隧道洞 口段造成的塌方實例很多，塑性地壓引起隧道擠出性破壞也時有發(fā)生，高地應(yīng)力區(qū) 的完整堅硬巖體常發(fā)生巖爆等。4）設(shè)計和施工不當(dāng)目前，大多數(shù)隧道都號稱采用“新奧法”設(shè)計和施工，由于對“新奧法”概念

26、 和原則的內(nèi)涵理解有偏差，所以在許多工程中遭到失敗。由于塌方誘發(fā)因素多、機理復(fù)雜，因此，在施工中針對復(fù)雜地質(zhì)時若處理 措施不當(dāng)，將極易造成塌方災(zāi)害的發(fā)生。塌方類型分析塌方類型的劃分方法有多種，一般根據(jù)塌方的原因、形式、規(guī)模、機理、 發(fā)生的部位等進(jìn)行劃分，主要分為以下五種形態(tài)：1）局部塌方：主要發(fā)生在大塊狀巖體中，由于巖體被結(jié)構(gòu)面切割后構(gòu)成不同形 狀的不穩(wěn)定結(jié)構(gòu)體。洞室開挖后，不穩(wěn)定結(jié)構(gòu)面的摩擦力向洞內(nèi)滑移而發(fā)生塌 方。2）拱形塌方：一般發(fā)生在層狀巖體或破碎塊巖體中，它有兩類，一類是在 坑跨范圍內(nèi)，僅出現(xiàn)在拱部；另一類是包括側(cè)壁崩塌在內(nèi)的擴大的拱形塌方。3）異形塌方：由于特殊地質(zhì)條件（溶洞、陷穴

27、等），淺埋、偏壓隧道等原 因產(chǎn)生的塌方。4）膨脹巖隧道塌方：由于高膨脹壓力作用在噴混凝土支護(hù)上；巖土體的膨 脹原因使摩擦和剪切強度損失，造成很大的巖石材料重力荷載；高水壓力積聚 等造成隧道塌方。5）大變形的隧道和巖爆：高地應(yīng)力狀態(tài)下的深埋、長大隧道及地下工程的 圍巖大變形問題已經(jīng)成為困擾地下工程界的難題和尚待進(jìn)行深人研究的重大課 題之一。2、隧道圍巖大變形分析隨著隧道工程以及地下工程的迅猛發(fā)展，其長、大、深的特點日趨明顯，而在 一定的圍巖地質(zhì)和環(huán)境地質(zhì)條件下則往往易于發(fā)生圍巖大變形等地質(zhì)災(zāi)害。根 據(jù)大量文獻(xiàn)檢索結(jié)果顯示，隧道工程圍巖大變形已是困擾地下工程界的一個重大 問題。隧道圍巖大變形研究現(xiàn)

28、狀國內(nèi)外學(xué)者已經(jīng)做過不少的探索工作，但由于大變形理論的研究不盡成熟，加 之現(xiàn)場地質(zhì)巖體狀況復(fù)雜性，目前的研究工作主要表現(xiàn)在以下方面。1）大變形的定義關(guān)于圍巖大變形，目前還沒有形成一致的和明確的定義。有的學(xué)者提出根據(jù) 圍巖變形是否超出初期支護(hù)的預(yù)留變形量來定義大變形。也有的學(xué)者認(rèn)為，不能從變形量的絕對值大小來定義大變形問題，具有顯著的變形值是大變形問題的外 在表現(xiàn)，其本質(zhì)是由剪應(yīng)力產(chǎn)生的巖體的剪切變形發(fā)生錯動、斷裂分離破壞，巖體 將向地下空洞方向產(chǎn)生壓擠推變形來定義大變形。2）關(guān)于軟巖的分析至今巖石工程學(xué)界仍未就軟巖的概念達(dá)成共識，軟巖的定義有十幾種之 多。ISRM國際巖石力學(xué)學(xué)會1990,19

29、93）定義的軟巖是指單軸抗壓強度為 25MPa的一類巖石；1984年煤礦礦壓名詞討論會（昆明）將軟巖定義為“強度 低、空隙大、膠結(jié)程度差、受結(jié)構(gòu)面切割及風(fēng)化影響或含有大量易膨脹粘土礦 物的松、散、軟、弱巖層（體）”；還有的學(xué)者將軟巖劃分為地質(zhì)軟巖和工程軟巖 兩類等等。3）大變形機制人們一般按形成機制將圍巖大變形分為兩類：一是開挖形成的應(yīng)力重分布超 過圍巖強度而發(fā)生塑性化。二是巖石中的某些礦物和水反應(yīng)而發(fā)生膨脹。水及 某些（膨脹性）礦物的存在，對于膨脹變形是必須的。、隧道圍巖大變形的類型與機制隧道圍巖大變形可以定義為：隧道及地下工程圍巖的一種具有累進(jìn)性和明顯 時間效應(yīng)的塑性變形破壞，它既區(qū)別于巖

30、爆運動脆性破壞，又區(qū)別于圍巖松動圈中 受限于一定結(jié)構(gòu)面控制的坍塌、滑動等破壞。1）隧道圍巖大變形的類型分析根據(jù)對圍巖大變形典型實例的分析和對大變形機制研究，可以按照不同的受 控條件對大變形進(jìn)行類型劃分：受圍巖巖性控制的大變形，受圍巖結(jié)構(gòu)構(gòu)造控制的 大變形和受人工采掘擾動影響的大變形三大類型large deformation mechanism of Tunnel surrounding rock2）隧道圍巖大變形機制研究圍巖的變形破壞首先取決于圍巖性質(zhì)，其中包括圍巖體的巖性、結(jié)構(gòu)條件，其 次受到圍巖的環(huán)境條件即地應(yīng)力的大小、地下水的發(fā)育分布狀況的影響 ，同時也 與圍巖的支護(hù)條件密切相關(guān)。一般而

31、言，隧道變形將經(jīng)歷初始變形、等速變形及加速變形3個階段。在隧道開挖初期，由于圍巖變形剛開始，巖體內(nèi)應(yīng)力場和位移場處于線性變化階 段，處于力學(xué)平衡狀態(tài)，這時圍巖處于初始變形階段。隨著開挖過程的進(jìn)行、 圍巖地應(yīng)力釋放、應(yīng)力狀態(tài)重新分布，引起某些區(qū)域局部變形、微裂隙產(chǎn)生、 應(yīng)力增加，使得巖體內(nèi)部微裂隙不斷增加和擴展。這時圍巖處于等速變形階 段。隨著圍巖變形的增長，裂隙進(jìn)一步擴展、連通、叢集，甚至局部貫通，圍 巖發(fā)生較大的變形，變形速率持續(xù)增加，直至整體失穩(wěn)坍塌，這時圍巖處于加 速變形階段。若局部變形發(fā)展過程中，圍巖系統(tǒng)受到外界干擾（如：降雨、人 工影響、振動等），則將促使其變形和破壞過程的加速發(fā)展。

32、3、隧道圍巖大變形的預(yù)測在大變形的預(yù)測方面，目前國內(nèi)外尚無實用的預(yù)測大變形的方法、日本學(xué)者 viladkar（1995）提出利用地層Q值的“臨界埋深法”，當(dāng)實際埋深大于臨界埋深時 圍巖應(yīng)視之為擠壓性圍巖，具有發(fā)生大變形的條件。但此種方法與開挖斷面及支 護(hù)不發(fā)生關(guān)系，與支護(hù)變形量的大小也無內(nèi)在聯(lián)系，當(dāng)實際埋深大于臨界埋深時可 能發(fā)生的支護(hù)變形值有多大難以確定。大變形的預(yù)測另一方法是，對于一個具有錨噴支護(hù)的洞室，采用彈塑性理論解 析公式計算其在地應(yīng)力作用下的最終洞壁位移，然后確定位移與地應(yīng)力及巖體強 度三者的關(guān)系（繪出曲線圖形）,如已知地應(yīng)力及巖體強度支護(hù)位移值及大變形的 等級可從圖中查得。4、隧

33、道圍巖大變形的支護(hù)對策交通隧道的支護(hù)包括初期支護(hù)和二次襯砌。對于軟巖隧道 ，支護(hù)的首要任務(wù) 是如何遏制初期支護(hù)的大變形。隨著人們對大變形現(xiàn)象認(rèn)識不斷深化 ，提出了各 種各樣的支護(hù)措施和手段，這些支護(hù)措施基本可以分為以下三大類1）剛性支護(hù)這種支護(hù)措施的核心是通過加大支護(hù)結(jié)構(gòu)的強度和剛度來抵抗巨大的圍巖 壓力，這種支護(hù)措施無論從技術(shù)上還是從經(jīng)濟(jì)上 ，都是欠合理的，現(xiàn)在已經(jīng)較少采 用。2）可縮支護(hù)這種支護(hù)的理論依據(jù)是允許圍巖發(fā)生適度的變形，以降低作用于結(jié)構(gòu)的支護(hù) 壓力,從而減少超挖量并降低支護(hù)強度?？煽s支護(hù)系統(tǒng)在國內(nèi)外煤礦巷道支護(hù)方面已經(jīng)取得一些成功的經(jīng)驗，但該方法只允許適度變形，若超出支護(hù)體系的允許變形范圍，這類支護(hù)結(jié)構(gòu)一般很難 抵擋圍巖的巨大壓力，該方法在交通隧道支護(hù)中的應(yīng)用效果并不理想。3）錨、注一體化圍巖加固-支護(hù)系統(tǒng)錨噴襯砌作為隧道初期支護(hù)的主要手段，也構(gòu)成了永久襯砌的重要組成部 分。噴錨襯砌是一種加固圍巖、充分利用圍巖自承能力的一種支護(hù)襯砌形式，并且快速及時，可以節(jié)約勞