New designs of supports for large chamber workings

1. Calculations of underground structures located in hard and soft rock masses weakened by joint systems should be carried out on the basis of physically nonlinear models taking into account not only the presence of the joints but also their structural characteristics (the characteristic distance between joints of each of these systems and their length). 2. When constructing schemes of the limit equilibrium of potentially unstable rock blocks, it is necessary to take into account the possible step character of their surfaces, which is a consequence of weakening of the rock mass by differently oriented joint systems. Movement of such blocks occurs in the direction of the slip surfaces of the step surface, determined by the dip angle of the shear-prone joint system. 3. To support the roof of chamber workings located in masses characterized by a large value of horizontal tectonic stresses andλ≫1, it is necessary to use yielding load-bearing structural members. One of the possible effective designs is the yielding reinforced-concrete arch (Fig. 5) realized in the machine hall of the Rogun hydrostation. 4. When designing the wall bolting of large chamber workings, it is expedient to take into account the load-bearing capacity of the rock-anchored arch forming around the working. The scheme of bolting proposed in the present article is one of the possible solutions.