| 摘要 |
PURPOSE: To enable non-destructively measuring the compressive strength of concrete, the thickness of a structure, and the depth of a cavity on the back of the structure by measuring the mechanical impedance of the structure which arises as a result of a reflected elastic wave. CONSTITUTION: Analysis is made using a technique (elastic wave transfer function method) for accurately analyzing a reflected elastic wave (50KHz or less) which provides poor resolution because of its great wavelengths and so could not be used conventionally. Thereby the compressive strength of concrete, the thickness of a structure (roll thickness in the case of a tunnel), and the depth of a cavity on the back of the structure are measured for evaluation of the durability of the structure. Signals are input to a signal input device A by means of a mechanical hammer or a pulsar. The signals input are reflected at the boundaries between the concrete and the cavity and between the cavity and the natural ground and are output as voltages by means of an acceleration sensor B. The voltages are passed through an amplifier C and displayed as a voltage-time curve on a wave analysis device D. This data is fed to a personal computer E and analyzed using the elastic wave function method and converted into the concrete strength, the cavity depth and the roll thickness and displayed. |
