Development and testing of experimental equipment to measure pore pressure and dynamic pressure at points outside a pipe leak
| 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.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.identifier.apacitation | Bailey, N. D. (2015). <i>Development and testing of experimental equipment to measure pore pressure and dynamic pressure at points outside a pipe leak</i>. (Thesis). University of Cape Town ,Faculty of Engineering & the Built Environment ,Department of Civil Engineering. Retrieved from http://hdl.handle.net/11427/13655 | en_ZA |
| dc.identifier.chicagocitation | Bailey, Nicholas David. <i>"Development and testing of experimental equipment to measure pore pressure and dynamic pressure at points outside a pipe leak."</i> Thesis., University of Cape Town ,Faculty of Engineering & the Built Environment ,Department of Civil Engineering, 2015. http://hdl.handle.net/11427/13655 | 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.ris | TY - Thesis / Dissertation AU - Bailey, Nicholas David AB - 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. DA - 2015 DB - OpenUCT DP - University of Cape Town LK - https://open.uct.ac.za PB - University of Cape Town PY - 2015 T1 - Development and testing of experimental equipment to measure pore pressure and dynamic pressure at points outside a pipe leak TI - Development and testing of experimental equipment to measure pore pressure and dynamic pressure at points outside a pipe leak UR - http://hdl.handle.net/11427/13655 ER - | en_ZA |
| dc.identifier.uri | http://hdl.handle.net/11427/13655 | |
| dc.identifier.vancouvercitation | Bailey ND. Development and testing of experimental equipment to measure pore pressure and dynamic pressure at points outside a pipe leak. [Thesis]. University of Cape Town ,Faculty of Engineering & the Built Environment ,Department of Civil Engineering, 2015 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/13655 | en_ZA |
| dc.language.iso | eng | en_ZA |
| dc.publisher.department | Department of Civil Engineering | en_ZA |
| dc.publisher.faculty | Faculty of Engineering and the Built Environment | |
| dc.publisher.institution | University of Cape Town | |
| 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 | Master Thesis | |
| dc.type.qualificationlevel | Masters | |
| dc.type.qualificationname | MSc (Eng) | en_ZA |
| uct.type.filetype | Text | |
| uct.type.filetype | Image | |
| uct.type.publication | Research | en_ZA |
| uct.type.resource | Thesis | en_ZA |
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