Multi-Sensor Based Condition Assessment System for Buried Concrete Pipe
Open Access
- Author:
- Iyer, Shivprakash
- Graduate Program:
- Civil Engineering
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- December 14, 2006
- Committee Members:
- Sunil K Sinha, Committee Chair/Co-Chair
Chao Hsien Chu, Committee Member
Mian C Wang, Committee Member
Andrew Scanlon, Committee Member
Bernhard R Tittmann, Committee Member - Keywords:
- Trenchless Technology
Condition Assessment
Multi-sensor
Ultrasonic NDT
Signal/Image Processing - Abstract:
- The American Society of Civil Engineers' 2005 Report Card for America's Infrastructure gave a D- grade to water/wastewater infrastructure . It has been estimated that up to 40% of the United States' underground infrastructure will have failed or will be on the brink of failure within 20 years, unless efforts are initiated to renew it. But system renewal requires adequate funding. According to an April 2000 report by the Water Infrastructure Network (WIN) Agency, "America's water and wastewater systems face an estimated funding gap of $23 billion a year between current investments in infrastructure and the investments that will be needed annually over the next 20 years to replace aging and failing pipes and meet mandates of the Clean Water Act and Safe Drinking Water Act". This necessitates the need to monitor, detect and prevent any unforeseen failures in the working of underground pipelines that are complex in nature. A reliable pipeline assessment system is necessary so that pipeline operators can develop cost-effective maintenance, repair, and rehabilitation programs. This research proposes an automated ultrasound-immersion-based inspection system that can add complementary pipe information (depth perception) to existing surface image assessments done on concrete pipes commonly used as gravity stormwater and sewer pipes. Most municipal pipeline systems in North America are inspected visually by mobile Closed Circuit Television (CCTV) systems to access the in-situ condition of buried pipes. The video images are examined visually and classified into grades according to extent of damage against documented criteria by human operators prone to fatigue, subjectivity and ambiguity. Additionally, current imaging systems like Sewer Scanning & Evaluation Technology (SSET) and CCTV are able to provide information from within the pipe regarding surface cracks in 2-D only and do not have the capability to provide depth perception. This thesis provides a proof-of-concept of an automated ultrasound-immersion-based inspection system to detect defects in buried concrete pipes. The inspection system is proposed as a two step approach. The first step is called a reconnaissance mission that uses the ultrasound transducer to scan a region of interest. A signal interpretation and classification scheme coupled with a post processing algorithm is proposed that classifies the region of interest into a clean or defect region. If the scanned region of interest belongs to a defect, the second step characterizes the region of interest with a C-scan imaging process that provides depth perception. Results have shown that the feature extraction, classification and post processing schemes proposed in this thesis provide a sound proof-of-concept for developing this inspection system into a field applicable tool. Such a tool can aid asset managers to quickly evaluate the status of their buried infrastructure, ultimately leading to a sustainable asset management system.