Author(s): Wolfram Kaempfer; Michael Berndt; Hans-Peter Hack; Dietmar Maelzer
Linked Author(s):
Keywords: Sewer network classification; Inspection technology; Service life; Ageingprogress; Progressive inspection and evaluation strategy; Cost-effective maintenanceand rehabilitation
Abstract: The technical ageing progress of heterogeneous materials follows an progressive sine curve development. The problem of model description for the ageing progress of sewer networks lies in their largely undocumented stress history. Within the framework of a joint R& D project, a simple model for determining the service life of sewers has been developed. The basis of the ageing model is provided by the statistical evaluation of the local ageing progress of sewer networks. The classification of pipe damage in sewers requires knowledge of exact defect dimensions, such as the width and depth of cracks, fractures and defective connections. Damage can be inspected and graded by means of TV technology. A quantitative evaluation of sewers is possible with the help of spatial laser technology or computer image operations. The ageing progress of sewer networks can be documented on the basis of timerelated changes in damage dimensions using different inspection intervals. The determination of service life requires not only knowledge of the local ageing progress, but also investigation of the ageing of pipe materials themselves by means of simulation or time-accelerating tests in laboratories. The target of a dynamic and progressive strategy for inspection, evaluation and rehabilitation is the investigation of the ageing progress on the basis of set priorities. A substantial contribution towards cost effectiveness is made by selective inspection strategies, which reduce the running costs for the cultivation of a sewer network register to an absolute minimum. The disadvantage of selective inspection strategies lies in the large amount of information required for the setting up of a sewer network register.
Year: 1999