22 – Pile Hammers

Publisher Summary Driving a stick into the ground can be done by one person with a hammer. In earlier times, piles were driven by dropping a weight on the pile. The weight was lifted using various lever and pulley mechanisms. Guiding systems were developed to guide the weight so that it would fall vertically. Early engineers who used this simple mechanism found out that it is more productive to use a smaller fall height. If the fall height is increased, then the time taken for a blow also will increase. It was more productive to have many low-energy blows than few high-energy blows. It was noted that low-energy blows could also minimize damage to piles. The chapter discusses steam-operated pile hammers, diesel hammers, hydraulic hammers, and vibratory hammers. Vibratory hammers consist of three main components: gear case, vibration suppressor, and clamp. Highest amplitude occurs at the start-up and finish of a vibratory pile driver. At start-up, weights inside the vibratory driver accelerate to achieve a high velocity. This induces a high amplitude at the beginning. High amplitude can cause damage to nearby buildings.