While constructing the underground excavation we need to know the primary stress field and also the stress and deformation redistribution in the surrounding rock mass. There are several methods to determine this redistribution, from the basic analytical methods for circular openings in the elastic medium, to the complex equations, which involve also other factors for determination of the stress redistribution and the formation of deformations. If the tunnel is being built in squeezing ground, we must pay an attention to much higher deformation, which can lead to support failure. This is why choosing the right support elements and the installing time of the support is crucial, while designing the underground object in squeezing ground conditions. If the support is installed to soon, then the high stresses on the tunnel lining will appear, which can lead to the support failure. If the support elements are installed too late, they will not have much effect in providing global tunnel stability. It is also important to choose ductile elements, which can take higher deformations without failure. Most common ductile support are yielding elements, which can take about 40% of deformation of its length, before they take the full support stress. The important element of tunnel construction in such conditions is also choosing the right excavation method. The most commonly used is New Austrian Method (NATM), which comprises a construction in phases and the in-situ determination of the installed support. Construction with TBM is mostly not used in squeezing ground, because in the case of a sudden stopping of drilling, the machine can be trapped in ground. Aside from that it is also important to perform monitoring of the construction of a tunnel and also to continue with it after the end of the construction, when the tunnel is in use.
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