Increasing efficiency of overcoming front resistance in cohesive soils during vibration pile driving
The article considers the peculiarities of vibration driving of piles and sheet piles in cohesive soils. Pile motion is analyzed using an elastoplastic model of soil resistance to make a conclusion of efficiency of unbalanced vibrations for overcoming the front resistance during driving into cohesive soil. The authors suggest a new design and a flow chart of a double-frequency vibratory pile driver with unequal loading and unloading speeds during pile element driving. The new flow chart of vibratory pile driving operation is based on concurrent working of two pairs of balance weights. Vibration nonuniformity is ensured by different rotation speeds of separate pairs of balance weights. The action of disturbing force of the initial and modified vibratory pile drivers is analyzed. Change in the work of the suggested machine with the change in the balance weight rotation direction is considered: in the pile driving and pulling mode. Unit operation in the self-synchronization mode is provided. The main parameters and elements of vibratory pile driver are estimated.