An investigation of ground accelerations produced by machines

Machines with reciprocating or rotating parts initiate stress waves which propagate through the ground and produce measurable ground motions in the vicinity of the machines. In many respects these ground motions may be objectionable. Consequently it is desirable to have a body of precise information on the ground motion produced by various common machines. Measurements of the ground acceleration produced by drop hammers, punch presses, railway trains, heavy automotive trucks, a cutting shear, a hydraulic press, and a pneumatic hammer were made. The vertical and two horizontal components of acceleration were measured at various distances from the source. The maximum ground acceleration component observed was 64.4 feet per second per second near a drop hammer. Ground accelerations as great as 1.6 feet per second per second were measured at a distance of one hundred feet from the source. The influence of ground acceleration on equipment, on machines, and on human beings is largely dependent on the maximum value of the ground acceleration but also may be markedly influenced by the character of the ground motion. The detailed character of the ground acceleration varies widely with the different sources of the motion, with distance from the source, and with the geology of the transmitting medium. To cover this aspect of the problem sixty-two acceleration time records of the ground motion are reproduced in the thesis