土木工程外文翻譯---在不良地質條件下的隧道掘進-建筑結構-wenkub
2023-05-19 14:10:10 本頁面
【正文】 nes and squeezing. Whenever available to the authors and based on project experience, the point of view is illustrated by case examples, which give the opportunity to underline specific difficulties encountered and remendations. INTRODUCTION TBM excavation represent a big investment in an unflexible but potentially very fast method of excavating and supporting a rock tunnel (Barton, 1996). When unfavorable conditions are encountered without warning, time schedule and practical consequences are often far greater in a TBM driven tunnel than in a drill and blast tunnel. The unfavorable conditions can be produced by either a rock mass of very poor quality causing instability of the tunnel or a rock mass of very quality (. strong and massive rock mass) determining very low peration rates. However, it is to be observed that when using the full face mechanized excavation method, the influence of the rock mass quality on the machine performance has not an absolute value: the 西南交通大學本科 畢業(yè)設計 第 2 頁 influence is in fact to be referred to both the TBM type used and the tunnel diameter. Right from the beginning of its earliest applications, the use of full face mechanized excavation was to overe the limits imposed by local geology, the economic challenges and schedule petitions of the drill and blast method and other socalled traditional excavation methods. A prominent example is given by the recent (from 1995 to 2020) construction of the one tube km long Laerdal Tunnel in Norway, the world’s longest road tunnel. The 100m*m cross section tunnel is being excavation in a Precambrian gneiss, a very good and stable rock mass: the supports are on average only 78 rock bolts plus a 7cm thick shotcrete lining per meter of tunnel. The excavation is carried out by the drill and blast method, which been evaluated to be less expensive and more reliable than the 。 faut zones。 ? The intensities of both the instability phenomena and the induced convergence also increase with increasing diameter of the excavation (Tseng et al., 1998。 the wider or narrower range of application of a single shielded TBM, with respect to the double shielded one, depends on the design and dimensioning of the TBM and on the type of limiting situations to be faced, rather than the TBM type。 in the design of TBM’s for rock and in the definition of special interventions for application to a given situation。 instead, a continuous collaboration and control of all design and construction details are essential by its intended user, the contractor. The is particularly true as far as there are still no “Accepted Standards” for the design and construction of a type TBM, and each TBM to be constructed is to be 西南交通大學本科 畢業(yè)設計
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