Design of sprayed concrete as hard rock reinforcement using yield-line theory

Yield-Line Theory (YLT) has been in wide spread use since the 1960's. YLT allows determining of the upper-bound bending resistance of reinforced concrete slabs using the concept of virtual work. YLT can be used for two purposes in the design of sprayed concrete support: the determination of quality assurance demands for the sprayed concrete or in the design of adequate sprayed concrete layer thickness against a bending failure. The square slab energy absorption test (EN 14488-5) and the round panel flexural toughness test (ASTM C1550-12a) are used. Solutions for both tests are given and conversion equations are derived. Testing results produced during normal quality assurance testing process in Länsimetro project (Finland) are shown for comparison. Finally, the merits and drawbacks of the test types are discussed.