Development and application of self-cleansing design criteria for sediment transport in sewer networks | |
| Author | Natchapon Vongvisessomjai |
| Call Number | AIT Diss. no.WM-09-05 |
| Subject(s) | Sediment transport--Mathematical models Sewerage--Mathematical models |
| Note | A dissertation submitted in the partial fulfillment of the requirements for the degree of Doctor of Engineering in Water Engineering and Management, School of Engineering and Technology |
| Publisher | Asian Institute of Technology |
| Series Statement | Dissertation ; no. WM-09-05 |
| Abstract | Sewer systems must convey the design ed discharge and s hould as far as possible be free from sediment deposit. Traditionally , a minimum flow velocity for non - deposition of a fixed value is used as a low flow criterion for the design of sewer systems. In the recent past, several studies on sedime nt deposition in sewer pipes have included all governing parameters of flow and sediment transport. However, a large amount of data is required for their application . Hence, for practical purposes, the simple minimum velocity self - cleansing criterion is st ill being used by the designers. The objectives of the present study are to develop simple and practice oriented self - cleansing sewer design criteria which take into account the important parameters and to incorporate the new criteria into a mathematical m odel, which can be used for the design and management of complex sewer networks which cannot be easily done. The first part of the study involved laboratory tests to determine new practical self - cleansing design criteria. A total of 64 laboratory experime nts are carried out using circular PVC pipes with uniform partially full flow . Based on the experiments, two self - cleansing design formulae, one for suspended load and another one for bed load have been derived and verified using dimensionless analysis . T he second part of this research is the development of a MOUSE ST model which is calibrated using the observed data in the sewer network of Pattaya city, east of Bangkok. The s imulated water depths in the network match well the observed data for both cali bration and verification while the simulated sediment depth s fit quite well with the observed field data. The developed self - cleansing design criteria in the first part of study is applied to the Pattaya sewer system using calibrated runoff and pipe flow s ub - models in the MOUSE ST model to predict potential sediment deposit locations which agreed well with the MOUSE ST simulation results obtained with well established sediment transport equations. Then MOUSE ST is applied with different scenarios to see th e effects and to provide solutions and recommendations to reduce the sediment deposit problem in the study system. The scenarios results indicate that the case s for the redesigned sewer system gi ve less sediment deposit compared to the existing condition. T he new self - cleansing formulae are expressed in simpler form and include all the important flow and sediment transport characteristics and agree well with the well - known sediment transport equations. The study also recommends the step - by - step design met hodology for simple sewers and complicated sewers. It is expected that the results of this study would lead to preliminary development of a new self - cleansing design method for sewer network. More raw experiment data from previous research and new experime ntal tests in the laboratory outside the author’s range are also needed to expand the range of application and ultimately leading to universal application of self - cleansing design criteria and procedure. |
| Year | 2010 |
| Corresponding Series Added Entry | Asian Institute of Technology. Dissertation ; no. WM-09-05 |
| Type | Dissertation |
| School | School of Engineering and Technology |
| Department | Department of Civil and Infrastucture Engineering (DCIE) |
| Academic Program/FoS | Water Engineering and Management (WM) |
| Chairperson(s) | Babel, Mukand Singh; |
| Examination Committee(s) | Sutat Weesakul ;Vilas Nitivattananon ;Tawatchai Tingsanchali; |
| Scholarship Donor(s) | Denmark; |
| Degree | Thesis (Ph.D.) - Asian Institute of Technology, 2009 |