The cross-sectional dimensions of caverns are generally far larger than those of tunnels. Not only the width, but also the height and the ratio of height to width of powerhouse caverns, for example, are considerably larger than those of traffic tunnels. Such caverns have been excavated in recent years with widths of 20 to 30 m and heights of 30 to 40 m. It is to be expected that caverns with even larger dimensions will be constructed in the future. New methods of construction, in which shotcrete and anchors are used to support the opening’s walls and serve at the same time as a permanent lining, are being adopted more and more in cavern engineering. Here again, great importance must be attached to the rock mass as the actual load-carrying medium, and the carrying out of stability analyses is imperative. Since investigations into bedrock conditions at the site of such structures are usually performed in a very detailed fashion, the basic information for a structural analysis may usually be determined relatively reliably. A separate chapter is dedicated to stability analyses for caverns in view of the above. The influence of the cavern’s dimensions, in-situ states of stress and the stages of construction on the distribution of stresses, the deformations and the loading of the support will be handled in this chapter using two and three-dimensional examples. Furthermore, questions arising as a result of non-elastic rock mass behaviour will be discussed, in addition to giving some general advice.
Unable to display preview. Download preview PDF.