1、 西 南 交 通 大 学 本科毕业设计 外文翻译 年 级 : 学 号 : 姓 名 : 专 业 : 指导老师 : 2012 年 6 月 西南交通大学本科 毕业设计 第 1 页 TBM TUNNELLING IN DIFFICULT GROUND CONDITION Giovanni Barla and Sebastiano Pelizza ABSTRACT This paper is to discuss TBM tunneling in difficult ground conditions, when problems are met which may reduce dramaticall
2、y the average progress rates and practical consequences may be such as to pose serious questions on the use of mechanized TBM tunnelling versus drill blast and other so-called traditional excavation methods. Following a few remarks on rock TBM tunnelling in relation to the selection and dimensioning
3、 of the machine, the attention is posed on the limiting geological conditions which may be envisaged with respect to the use of TBM tunnelling and on the importance of geological and geotechnical investigations, in order to derive an appropriate understanding of the rock mass conditions along the li
4、ne of the tunnel. The discussion is centered upon the relatively more important or difficult ground conditions including borability limits, instability of excavation walls, instability of excavation face, fault zones and squeezing. Whenever available to the authors and based on project experience, t
5、he point of view is illustrated by case examples, which give the opportunity to underline specific difficulties encountered and recommendations. INTRODUCTION TBM excavation represent a big investment in an unflexible but potentially very fast method of excavating and supporting a rock tunnel (Barton
6、, 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 t
7、he tunnel or a rock mass of very quality (i.e. strong and massive rock mass) determining very low penetration 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:
8、the 西南交通大学本科 毕业设计 第 2 页 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 overcome the limits imposed by local geology, the economic challenges and schedule c
9、ompetitions of the drill and blast method and other so-called traditional excavation methods. A prominent example is given by the recent (from 1995 to 2000) construction of the one tube 24.5 km long Laerdal Tunnel in Norway, the worlds longest road tunnel. The 100m*m cross section tunnel is being ex
10、cavation in a Precambrian gneiss, a very good and stable rock mass: the supports are on average only 7-8 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
11、 ；use of alarge diameter TBM. The average progress rate is 4.8 5.0 km per year with two faces, against the 2.3-4.8 km per year, estimated for a large diameter TBM (Kovari et al., 1993) With this background in mind, this paper is intended to address the problem of TBM tunnelling in difficult ground c
12、onditions. Based on a few selected case examples, the discussion is centered upon the relatively more important or difficult ground conditions which can be listed as follows: borability limits； instability of excavation walls； instability of excavation face； faut zones； squeezing. ROCK TBM TUNNELLIN
13、G The practically infinity number of combinations rock, soil and environmental conditions which may be encountered during tunnel excavation has determined a great difference in the types and characteristics of the available TBMs . There are many different schemes for the classification of tunnelling machines. For the example the AITES/ITA Working Group No.14 (Mechnisation of Excavation ) is currently working on the definition of an internationally acceptable classification of TBMs with the purpose of establishing terminology and “terminology” for the optimum choice of the machine (Table 1).
