Ground condition monitoring using friction generated acoustics

Tyler, T., 2004. Ground condition monitoring using friction generated acoustics. PhD, Nottingham Trent University.

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Abstract

The development of a novel technique used to characterise ground structures from the acoustic emission generated during a drilling process is presented. Existing ground evaluation techniques were investigated, providing an insight to the relevant parameters, which are useful to the engineer. The literature review considers areas of soil mechanics, granular physics, frictional interactions between solids and solid-granular interfaces as well as the acoustic emission associated with frictional mechanisms. The drilling process was simplified by using a rotating probe, which maximised surface interactions as well as reducing other frictional mechanisms associated with material removal and penetration depth. An experimental apparatus was developed, which consisted of a conical tipped rotating probe that was pushed into granular samples at a controlled feed rate, thus simulating a typical drilling process. The drill string acted as an acoustic wave guide and the acoustic signal was recorded using a suitable coupling device. Preliminary investigations were used to optimise the experimental apparatus for further investigations. Investigations focused on determining the effects that the applied load and sliding velocity had on the acoustic parameters. The effects of varying particulate density, particle size and water content were also considered. A series of standard soil investigation techniques have been conducted to provide information directly associated with the soil samples used in this study. Both peak shear and residual shear forces were considered and the analysis focused on varying grain size, density and water content. Frictional interactions between the probe-tip and different grades of abrasive paper were also considered. Results obtained from the abrasive paper investigations led to the development of an unusual thresholding technique which was used to determine a characteristic signal of the friction pair. Investigations identified a repeatable correlation between the characteristic signal and the average particle size. Further investigations highlighted that the acoustic energy could be used in conjunction with the characteristic signal to obtain more information about the granular material being investigated. Results presented in this thesis provide evidence that ultrasonic monitoring of drilling has potential for real time ground condition monitoring applications.

Item Type:	Thesis
Creators:	Tyler, T.
Date:	2004
ISBN:	9781369313307
Identifiers:	Number Type PQ10183038 Other
Divisions:	Schools > School of Science and Technology
Record created by:	Linda Sullivan
Date Added:	28 Aug 2020 14:49
Last Modified:	22 Jun 2023 08:44
URI:	https://irep.ntu.ac.uk/id/eprint/40594

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