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Ten years of advanced culvert research: A retrospective
Published in Joan-Ramon Casas, Dan M. Frangopol, Jose Turmo, Bridge Safety, Maintenance, Management, Life-Cycle, Resilience and Sustainability, 2022
D. Becerril García, N.A. Hoult, I.D. Moore
As indicated earlier, deteriorated culverts could be replaced or left unrepaired but an alternative approach is to rehabilitate them. Sliplining is a common method for culvert rehabilitation, which consists of placing a slightly smaller diameter pipe inside the deteriorated host pipe and subsequently grouting the annular spacing between them. However, the response of these composite structures had received little attention a decade ago. To address this need, Simpson et al. (2015) undertook a series of experiments on a deteriorated CSP culvert with a 1.8 m diameter and a corrugation profile of 13×68, and an intact thickness of 4.5 mm buried and subjected to simulated vehicle loads at two different burial depths (0.6 and 0.9 m) before and after being rehabilitated with a grouted HDPE slipliner. The specimen had light corrosion located on both sides of the invert, under the haunches. The HDPE liner had a spirally wound box structure with internal and external diameters of 1.5 and 1.7 m, respectively. Results from the test program indicated that the rehabilitated culvert was significantly stiffer than the unrehabilitated pipe since diameter changes were reduced by more than 90%. Post-test calculations indicated that the rehabilitated system behaved as a semi-rigid pipe. Another interesting result was that the deteriorated host pipe and the grout carried most of the load. Results also indicated that the dominant carrying mechanisms were bending moment in the crown/shoulders regions and thrust across the springlines.
Trenchless Equipment
Published in John E. Schaufelberger, Giovanni C. Migliaccio, Construction Equipment Management, 2019
John E. Schaufelberger, Giovanni C. Migliaccio
Sliplining is another well-established method for trenchless replacement of worn-out and undersized water and sewer lines. Similarly to pipe bursting, sliplining replaces an existing pipe, size-for-size, with a new pipe at the same location. Whereas sliplining does not allow upsizing (i.e., replacing a pipe with one of larger diameter), it sometimes allows capacity to be moderately increased by using a pipe with better flow rate. The technique is most advantageous in cost terms when (a) there are few lateral connections, (b) the condition of the old pipe allows the new pipe to be slipped into it. Typical sliplining involves the insertion of the new pipe into the existing pipe by either pulling or pushing. Hydraulic excavators are often used to push the new pipe into the conduit of the old pipe. The space between the new and the old pipe may be grouted to improve the structural performance of the new system.
Rehabilitation
Published in David Butler, Christopher Digman, Christos Makropoulos, John W. Davies, Urban Drainage, 2018
David Butler, Christopher Digman, Christos Makropoulos, John W. Davies
Sliplining involves forming a continuous length of plastic (such as high-density polyethylene [HDPE]) lining and pulling it through the existing pipe. One approach is for long lengths of plastic pipe (typically 5 m) to be welded/fused end-to-end on the surface. The resulting continuous length of pipe has some flexibility and is winched along the sewer via a specially excavated lead-in trench (Figure 18.4a). The winch cable is attached to a nose-cone fixed to the front end of the new lining. As an alternative to welding the lengths on the surface, pipes can be welded in an enlarged trench (Figure 18.4b). The first approach has the disadvantage that it requires space on the surface for assembly of the pipe length; the second requires more excavation (though both approaches require a significant amount). Another alternative is much shorter lengths of pipe (HDPE or polypropylene) with push-fit or screw joints. These are connected within existing manholes (Figure 18.4c). In all cases, any significant space between the new lining and the old pipe is filled with grout. The selection and use of grout can be the most difficult aspect of sliplining. The design must consider whether the grout needs to transfer load between the host and new pipe, or act as a restraint. During application of the grout, care must be taken to keep the inserted pipe fixed in position to avoid flotation, typically through filling the smaller pipe with water and applying the grout in stages.
Sensitivity-based adaptive procedure (SAP) for optimal rehabilitation of sewer systems
Published in Urban Water Journal, 2022
Xiatong Cai, Hamidreza Shirkhani, Abdolmajid Mohammadian
The independent variables have two components: hydraulic rehabilitation and deterioration rehabilitation. Deterioration rehabilitation strategies include (a) Do Nothing, (b) Routine Cleaning, (c) Shotcrete, (d) Cured-in-place Pipe, (f) Reinforced Fiberglass Sliplining and (g) Dig and Replace with Concrete Pipe (Altarabsheh, Kandil, and Ventresca 2018; Wirahadikusumah, Abraham, and Castello 1999). The six methods are trenchless methods and are considered as structural reinforcement (Zhu et al. 2021). In the optimization process, the HRCM model has multiple layers. The first layer is the selection of a proper rehabilitation strategy. Among the six rehabilitation methods, only the solution ‘(g) Dig and Replace with Concrete Pipe’ (Figure 2) will activate the system overflooding module to change the pipe diameter to improve the hydraulic performance of the system, even though all the rehabilitation methods will activate the system breakage risk module. The first layer uses discrete variables: strategy. The second layer consists of the system overflooding modules, which uses continuous variables: pipe diameter. It was shown that using a continuous variable at the second layer will exhibit better HRCM model performance than using the discrete variable. Moreover, removing constraints for objective functions can increase computational speed without compromising accuracy (Cai, Mohammadian, and Shirkhani 2020). The pipe diameter will be ceiled to the nearest actual commercial diameter at a post-processing step after optimization.