Considering Debonding in Design of Cementitious Liners within Concrete Pipes
Bibliographic record
Abstract
Many reinforced concrete pipes currently in service are experiencing unsafe levels of deterioration, and if left unattended may become susceptible to collapse. Rather than proceeding with full replacements, many municipalities opt to rehabilitate damaged concrete pipes using trenchless technologies. For example, the application of cementitious liners can avoid the costly excavations and traffic impediments associated with the installation of new pipes, while restoring the structural integrity and guarding against further deterioration. The design methods previously proposed provide guidance for selecting the required cementitious liner thickness to rehabilitate damaged concrete pipes such that the repaired pipe will remain protected from stormwater ingress and further deterioration. These calculations were based on limiting the tensile strains within the liner at the pipe crown that result from the bending moments induced by earth loading. However, that design approach operates on the assumption of perfect bond between the liner and the host pipe where the effects of debonding were not explored. In the current study, the design method is supplemented by additional calculation procedures addressing the debonded condition. Sample calculations for the debonded condition are presented for the rehabilitation of several pipe geometries experiencing varying levels of deterioration. These calculations indicate the existence of unsafe ranges of liner thickness for the debonded condition. The bounds of these unsafe ranges of liner thickness depend on the curvatures resulting from earth loading and the length of the moment arm within the liner (spanning from the neutral axis to the extreme fiber experiencing tension). The calculation procedures in the current study should be used to verify whether the liner thicknesses suggested from the bonded version of the design method become unsafe if debonding were to occur. The calculations also show the potential benefits of actively facilitating debonding within the liner.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".