Behavior of the overturning of mobile cranes due to penetration of outriggers caused by failure of ground

摘要

Overturning of mobile cranes due to penetration of outriggers into ground frequently occurs. This paper examines interrelation between instability of mobile cranes and penetration of outriggers due to failure of ground. Simulation of the overturning is performed by using a newly developed model mobile crane in centrifuge to equivalent an acting pressure through the outriggers between a prototype and the model. Experimental results show that mobile cranes become unstable due to rapid penetration of outriggers caused by brittle failure of the layered ground, which comprise hard surface overlying on soft ground, comparing W slowly penetration on the uniform soft ground. Since reverse analysis by using experimental records are performed to clarify the kinetic Condition of the overturning, it is observed that mobile cranes satisfy the kinetic condition of overturning due to rapid penetration In the layered ground prior to the static limitation of the equilibrium. Moreover, the relative instability index, which is introduced by dividing the kinetic condition of the overturning by the theoretical static limitation indicates almost constant value where the ground condition is same even though the condition of the crane (i.e., jib length and jib angle et al) is different. Consequently, it is clarified that stability of mobile cranes greatly depends upon a behavior of the penetration induced by the failure characteristics of ground.