Dynamic analysis of underground cavern´s roof under motorcade load with thick-plate theory

The roof was regarded as unidirectional or rectangular thick plate by Reissner theory and the motorcade dynamic load was looked on as harmonic load. The practical formulas of frequency, vibration model, deflection, internal force, stress, displacement and dynamic magnification factors for roof were obtained on the condition of various boundary and the deflection failure criterion was built. Taken the cavern roof of Wenfu phosphate mine for example, the parameters of roof were calculated. The results show that the roof deflection with thick plate theory is 1.64 times compared to the deflection with thin plate theory. The thickness factor is the biggest on clamped support boundary and it is the smallest on simply supported boundary and it´s the second place when one end of roof is fixed and the other end is simple support. The thickness factor increases with the ratio of plate thickness to span. The dynamic magnification factors are bigger when the angular frequency of harmonic load is closer to the fundamental frequency of thick plate. The resonance will appears between the motorcade and roof when the angular frequency of harmonic load equals to the plate´s fundamental frequency.