The purpose of this study is to develop new methods for soil type classification, mainly grain size distribution, using AE (Acoustic Emission) sensor and accelerometor under the invisible condition. These methods utilize the sound and the vibration phenomena which is generated while penetrating a cone into a soil or while shaving a bit on a ground surface.
The penetration cone is provided with an AE sensor and an accelerometor for measuring sound and vibration of cone and with a load cell for measuring penetration resistance. Laboratory experiments have been performed on several kinds of soil which have different grain size distributions. The results of the laboratory experiments indicate that both the mean value of the AE signal and the acceleration increase with the increase in the penetration resistance and in the 30% grain diameter
D30.
The sliding contact type soil classification device, which is equipped with AE sensor, is also experimented. The results of the primary experiments show that the different AE power spectrum appear with variation of soil grain sizes and the AE power spectrum is not depended upon a sliding speed or a load.
The penetration cone method is applied to a subway tunnelling works by a earth pressure balance type shield machine to investigate its usefulness for soil classification in the invisible chamber. The results of the field tests are agree with the data of laboratory experiment.
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