METHOD FOR MEASURING STRENGTH OF GROUND

摘要

PURPOSE:To measure the strength of the ground instantaneously and to accurately control the quality of earthwork by the feedback of a measurement result by making a weight which falls naturally from proper height strike the surface of the ground and measuring a shock waveform by a sensor fitted to the weight. CONSTITUTION:The weight 1 made of a strong and lightweight material such as duralumin has a plane as the reverse surface of its tip part 4 and is equipped with plural load meters 2 and an accelerometer 3 as sensors. This weight 1 is fallen freely from the proper height to strike the ground surface and the shock waveform (impact force waveform and acceleration waveform) is measured by the load meters 2 and accelerometer 3. A data processing part 5 processes the shock waveform according to measurement data from the weight 1 to find a natural oscillation frequency within an oscillation frequency range wherein the impact force is proportional to the acceleration, thereby finding and sending a numeral corresponding to a ground coefficient obtained by a flat plate loading test to a display part 6. In this case, the power spectrum of the shock waveform is found relatively easily by using the algorithm of fast Fourier transformation.