A Trap-door experimental study on dynamic loads on the support of underground openings due to earthquake shaking

Rock load concept was first proposed by Terzaghi in 1946 and it served as an essential item for designing underground structures and many modern rock classifications utilize this concept. Terzaghi’s trap-door experiments and following experimental studies have been carried out under static conditions. Therefore, it is important to check this commonly used concept and reevaluate the present design philosophies for dynamic conditions. In this study the authors performed trap-door experiments including both static and dynamic aspects by considering various discontinuity patterns including the original model tests of Terzaghi. The experiments showed that the discontinuity pattern has great influence on possible rock loads, and it may be increased by earthquake shaking. The authors describe experiments and present experimental results and discuss their implications in practice.