Cut and cover tunneling method pdf
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This method—in which a trench is excavated from the surface, then re-covered—is usually more economical and more practical than mined or bored tunneling. Cut-and-cover tunneling is extremely versatile. Depending on the situation, a variety of different construction methods can be used.
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Cut and cover
We all know that tunnels are essential to modern infrastructure, but what is the best way to drill a tunnel? Each method holds a set of strengths and weaknesses that make it the better approach for certain applications. NATM is both a construction method and a design philosophy. The philosophy looks to use the strength of the surrounding soil to the greatest extent possible to strengthen the tunnel structure. In other words, ground conditions drive the tunneling operation. The NATM philosophy also promotes constant monitoring.
The numerical models discussed in this paper are developed in finite element method FEM , finite deference method FDM , boundary element method and discrete element method and these tools are used to illustrate the behavior of tunnel structure deformation under different loads and in complicated conditions. Predicting the effect of all natural factors on tunnels is the most difficult method. One of the most significant advantages of the numerical method is in predicting the critical area surrounding the tunnel and the tunnel structure before making the tunnel construction due to different loads. Numerical modeling is used as control method in reducing the risk of tunnel construction failures. Since some factors such as settlement and deformation are not completely predictable in rock and soil surrounding the tunnel, using numerical modeling is a very economical and capable method in predicting the behavior of tunnel structures in various complicated conditions of loading.
The “Cover and Cut” method for tunnel construction was originally developed for urban subway structures where the least possible disruption of traffic is required.
Tunnels are dug in types of materials varying from soft clay to hard rock. The method of tunnel construction depends on such factors as the ground conditions, the ground water conditions, the length and diameter of the tunnel drive, the depth of the tunnel, the logistics of supporting the tunnel excavation, the final use and shape of the tunnel and appropriate risk management. Tunnel construction is a subset of underground construction.
The state of the art and future research in cut and cover tunneling is described. The operations described in this paper are usually performed sequentially on a cut and cover construction project; these include: relocating utilities; underpinning adjacent structures; dewatering where required; temporary street decking; installing ground support systems; and, excavating below street level. Future research in cut and cover tunneling will include ways to minimize environmental, social and economic impacts.
Tunnel Engineering Handbook pp Cite as. Shallow-depth tunnels, such as large sewer tunnels, vehicular tunnels, and rapid transit tunnels, are frequently designed as structures to be constructed using the cut-and-cover method. For depths up to 35—45 ft this method is often cheaper and more practical than underground tunneling, and depths of 60 ft or more are quite common for rapid transit cuts. This chapter discusses the design and construction of the larger cast-in-place concrete structures used as sewer tunnels or transportation tunnels for pedestrian, vehicular, or rapid transit traffic. The tunnel is typically designed as a box-shaped frame, and due to the limited space available in urban areas, it is usually constructed within a braced excavation.
Наклонился и осмотрел пальцы левой руки. Лейтенант следил за его взглядом. - Ужасное уродство, правда. Но не искалеченная рука привлекла внимание Беккера. Он увидел кое-что другое. И повернулся к офицеру.
Да. Кошачья жила. Из нее делают струны для ракеток. - Как мило, - вздохнула. - Итак, твой диагноз? - потребовал. Сьюзан на минуту задумалась. - Склонность к ребячеству, фанат сквоша с подавляемой сексуальностью.
- За счет заведения.