Sedimentation of Hong Kong's Underground Culverts: Problems and Solutions
香港地底渠道內的積物：難題與方案
Student thesis: Doctoral Thesis
Author(s)
Related Research Unit(s)
Detail(s)
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| Award date | 7 Sept 2023 |
Link(s)
| Permanent Link | https://scholars.cityu.edu.hk/en/theses/theses(fc5e0784-c112-4159-a088-c050de8df7a4).html |
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| Other link(s) | Links |
Abstract
This PhD thesis gives an in-depth study of sedimentation causes and problems of Hong Kong’s underground culverts and presents the development of an innovative sediment desilting method (ISDM) appropriate for the Hong Kong urban drainage systems.
Documented government and news reports of recent decades clearly indicated that prevailing desilting approaches either neglected or were ineffective in dealing with drainage sedimentation problems inside Hong Kong’s underground culverts that occasionally led to flooding and even fatal accidents. The causes of these tragic events of early 2000s’ underground culverts desilting works were investigated and reported by the government’s civil works department. Remedial works were contracted out to specialist contractors to prevent future incidents. The author’s company is the major contractor for this undertaking, for which the author is responsible as its project initial concept, design, and management. With the consent of the company, this project forms the backdrop and testing ground for this research study.
To lay a solid foundation for this research and development study, in-depth literature reviews of sedimentation problems and existing methods of sediment desilting are conducted. These reviews helped to highlight the key challenges encountered in desilting works in general and confined settings like the underground culverts in particular. Findings from the literature reviews give a sound knowledge foundation for the subsequent ISDM development and implementation work.
This PhD research comprises five phases:
1) Existing Problems and Situation Analysis (Chapter 1 and 4)
2) Literature Review (Chapter 2)
3) Development of the Innovative Sediment Desilting Method “ISDM” (Chapter 5)
4) Trial Implementation of the ISDM (Chapter 6)
5) System Improvement - ISDM 2.0 (Chapter 7)
The methodology adopted in this study is essentially a case-based research coupled with the use of a standard engineering design framework for the development of the ISDM system. The process involved generation of innovative solutions, critical evaluation of alternatives, systematic and structured considerations of functional requirements and design features. This systematic approach with key considerations (derived from sedimentation background study, existing problems analysis and supplemented by literature review findings) led to the development of the ISDM. The subsequent trial implementation helped to rectify shortcomings of the proposed system.
A practical desilting system should be well integrated with other operational elements and capable of delivering desired productivity (e.g., desilted volume, lead time, running distance, and repair frequency). The ISDM implementation achieved the contractual volume and exceeded historical desilting records. And feedback from the government engineers clearly indicates the feasibility and usefulness of the proposed ISDM. Practical ISDM operational data have been documented and would be a valuable reference for future system enhancement.
The goals of this research have largely been achieved. The development and successful trial implementation of the ISDM system are evidence of a significant contribution. Its innovative features include propelling devices, hydraulic digging, centralized system navigation and cable control. The thesis closes with recommendations of how the ISDM may be further improved with the application of wireless technology connection.
Documented government and news reports of recent decades clearly indicated that prevailing desilting approaches either neglected or were ineffective in dealing with drainage sedimentation problems inside Hong Kong’s underground culverts that occasionally led to flooding and even fatal accidents. The causes of these tragic events of early 2000s’ underground culverts desilting works were investigated and reported by the government’s civil works department. Remedial works were contracted out to specialist contractors to prevent future incidents. The author’s company is the major contractor for this undertaking, for which the author is responsible as its project initial concept, design, and management. With the consent of the company, this project forms the backdrop and testing ground for this research study.
To lay a solid foundation for this research and development study, in-depth literature reviews of sedimentation problems and existing methods of sediment desilting are conducted. These reviews helped to highlight the key challenges encountered in desilting works in general and confined settings like the underground culverts in particular. Findings from the literature reviews give a sound knowledge foundation for the subsequent ISDM development and implementation work.
This PhD research comprises five phases:
1) Existing Problems and Situation Analysis (Chapter 1 and 4)
2) Literature Review (Chapter 2)
3) Development of the Innovative Sediment Desilting Method “ISDM” (Chapter 5)
4) Trial Implementation of the ISDM (Chapter 6)
5) System Improvement - ISDM 2.0 (Chapter 7)
The methodology adopted in this study is essentially a case-based research coupled with the use of a standard engineering design framework for the development of the ISDM system. The process involved generation of innovative solutions, critical evaluation of alternatives, systematic and structured considerations of functional requirements and design features. This systematic approach with key considerations (derived from sedimentation background study, existing problems analysis and supplemented by literature review findings) led to the development of the ISDM. The subsequent trial implementation helped to rectify shortcomings of the proposed system.
A practical desilting system should be well integrated with other operational elements and capable of delivering desired productivity (e.g., desilted volume, lead time, running distance, and repair frequency). The ISDM implementation achieved the contractual volume and exceeded historical desilting records. And feedback from the government engineers clearly indicates the feasibility and usefulness of the proposed ISDM. Practical ISDM operational data have been documented and would be a valuable reference for future system enhancement.
The goals of this research have largely been achieved. The development and successful trial implementation of the ISDM system are evidence of a significant contribution. Its innovative features include propelling devices, hydraulic digging, centralized system navigation and cable control. The thesis closes with recommendations of how the ISDM may be further improved with the application of wireless technology connection.
