Development and testing of experimental equipment to measure pore pressure and dynamic pressure at points outside a pipe leak

 

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dc.contributor.advisor Van Zyl, J E en_ZA
dc.contributor.author Bailey, Nicholas David en_ZA
dc.date.accessioned 2015-08-10T06:14:41Z
dc.date.available 2015-08-10T06:14:41Z
dc.date.issued 2015 en_ZA
dc.identifier.citation Bailey, N. 2015. Development and testing of experimental equipment to measure pore pressure and dynamic pressure at points outside a pipe leak. University of Cape Town. en_ZA
dc.identifier.uri http://hdl.handle.net/11427/13655
dc.description Includes bibliographical references. en_ZA
dc.description.abstract Leaks in water distribution mains are a major issue throughout the world. The amount of water lost through these leaks is unacceptable for a resource, which is becoming ever scarcer. Little is known about the fundamentals, which exist outside leaking water distribution mains. The se fundamentals are the interaction between the leaking water and the soil surrounding the distribution main. This interaction is known as the leak - soil interaction. Research has found that a phenomenon called internal fluidisation typically occurs in the soils outside of leaks in distribution mains. Internal fluidisation is a complex interaction between the leak and the surrounding soil, whereby the soil losses its intermolecular bonding and becomes displaced by the water jet generated by the leak. It is believed that this complex phenomenon causes large energy losses. Subsequently, many water leaks are not able to propagate to the ground surface where they will be visible. This leads to many such leaks being undetected below the ground surface. The objective of this study was to develop an experimental setup, which simulated the internal fluidisation phenomenon. The setup consisted primarily of an orifice, simulating a leak in a distribution pipe; surrounded by ballotini (glass beads), as the soil medium surrounding the pipe; and the measurement instruments, which were Pitot tubes. When using the experimental setup, pore pressures and dynamic pressures around the leak and therefore within the ballotini bed were measured using two Pitot tubes. The accuracy and repeatability of these measurements were also of importance and were investigated. The accuracy of the measurements were dependant on the precision of the Pitot tubes in taking measurements. They were found to have an error of up to 4.1 %, although the experiment to test for the accuracy was not fool proof. The repeatability of the measurements was found to have a 3.8 % average difference between the previous and repeated measurements. The measuring of the pore pressures and dynamic pressures resulted in the following findings, which were the most important in the study: There were large vertical velocities found in the fluidized zone, where outside of this zone they were significantly smaller. The largest pore pressure was found to occur near the top of the fluidised zone. The pore pressures in the bed from a certain distance away from the orifice had a linear distribution, illustrating that Darcy water flow was present. High energy existed in the fluidised zone where it was greatest nearest the orifice and decreased to the top of the fluidised zone. In the ballotini bed outside of the fluidised zone the energy was found to be considerably smaller and decreased further away from the orifice. en_ZA
dc.language.iso eng en_ZA
dc.subject.other Civil Engineering en_ZA
dc.title Development and testing of experimental equipment to measure pore pressure and dynamic pressure at points outside a pipe leak en_ZA
dc.type Thesis / Dissertation en_ZA
uct.type.publication Research en_ZA
uct.type.resource Thesis en_ZA
dc.publisher.institution University of Cape Town
dc.publisher.faculty Faculty of Engineering & the Built Environment en_ZA
dc.publisher.department Department of Civil Engineering en_ZA
dc.type.qualificationlevel Masters en_ZA
dc.type.qualificationname MSc (Eng) en_ZA
uct.type.filetype Text
uct.type.filetype Image


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