One of the major issues in civil engineering and the construction industry is urban development on soft soil. It requires special foundations and pile driving works.
A more detailed understanding of factors which influence the efficiency of vibratory pile-driving together with new concepts for generating unidirectional vibrations are required.
The project has resulted in the development of improved models for predicting the driveability and vibration levels of vibratory driven sheet-piles; analysis techniques for variable-eccentricity, variable-frequency pile-drivers, whose vibration can be varied by the controlled phase synchronisation of pairs of contra-rotating eccentrics; the DSP implementation of a non-linear control system for brushless dc drives which accounts for the mechanical coupling of multiple eccentric disturbances and provides the required dynamic performance over the complete operating frequency range 0 to 50Hz; and a full understanding of the dynamic operation of vibrators based on pairs of contra-rotating eccentrics, be they hydraulically or electromagnetically actuated.
Fundamental research will be undertaken to establish an improved physical model of the pile-driving action in order to investigate how the soil, pile, and vibrator parameters influence driving under the combined weight of the element and vibrator. Predictions will be validated against site tests of different soil characteristics for which optimum vibrator parameters will be obtained. Novel forms of electromagnetic actuation systems will be examined and the potential for large and very large versions inveigated. The most promising concepts will be embodied in prototype devices whose performance will be assessed against predictions.