The cyclic mobility of a fine dense sand due to the load-unloading cycle and vibration of a large dragline

At an open pit coal mine in Southern Saskatchewan, Canada, the design support level for a 75-cubic-meter-bucket dragline consists of a saturated dense fine sand. The Dehavior of this sand during the excavation of a test pit created a concern. The sand essentially turned into a fluid state during the excavating and it was observed that if a lump of this dense intact sand was shaken in the hand, it would flow readily into a flat pat of soil. It was thought possible that the cyclic loading and unloading together with any possible vibrations of the dragline might cause the sand to liquefy, thereby endangering the stability of the highwall and, in turn, the safety of the dragline.