In 2018, the design organisation SiberDorProekt LLC began work on the design of the following facility in Novosibirsk Region: «Major repair of a culvert in Novosibirsk District, Novosibirsk Region». The culvert is located at PK0+86.91 along the axis of the Novosibirsk — Krasny Yar road (corresponding to km 7+085 of the operational kilometre reference) and has the following characteristics:
- length — 19.1 m;
- four-cell, circular reinforced-concrete culvert, with each cell consisting of 18 sections (type ZKP)
- diameter of each cell at the time of design — 1.5 m;
- headwall type — portal with sloping walls.
During the inspection of the culvert, no cracks or signs of leakage were found in the sections, and there were no settlements of the embankment or cracks in the road pavement. The main defect was vertical and horizontal displacement of the sections, which occurred during the culvert construction stage due to insufficient compaction of its foundation. In addition, the sections were displaced as a result of mechanical impact from construction equipment during pipe backfilling. The vertical displacement of the sections led to water stagnation inside the culvert and, consequently, had a destructive effect on the reinforced-concrete elements.
Based on the preliminary design inspection and recommendations, three options for the major repair of the culvert using the sleeving method were developed and submitted to the client for review during preparation of the design documentation.
Culvert major repair options
The first repair option considered was sleeving with metal pipes. The technology involves restoring the vertical geometry by installing an additional pipe with the maximum possible diameter inside the existing pipe and filling the voids formed between the pipes with an injection compound. The diameter of the metal sleeve pipe was 1.22 m.
The main advantage of this technology is the metal pipe’s resistance to mechanical damage. However, the main disadvantage of the first option is a significant reduction in the internal diameter of the pipe during repair and, consequently, a decrease in the water conveyance capacity of the structures.
Installation also requires access areas for construction equipment, as well as the use of heavy machinery and equipment, resulting in longer work periods and high costs. In addition, additional operating costs would be required for installing and restoring the anti-corrosion coating of the metal pipe.
The second option (approved for use) was the major repair of the culvert using permanent formwork in the form of an anchored sheet, applying the «PipeArm» technology. This technology involves installing a polymer protective sleeve «PipeArm» with a reinforcing cage inside the culvert body and injecting a special mineral-binder-based solution into the space between the existing culvert body and the polymer sleeve.
The method was developed in accordance with ODM 218.3.046–2015 «Recommendations on the technology for repairing culverts using composite materials». Its main advantages are minimal reduction of the internal diameter of the existing structure, restoration of load-bearing capacity and stopping the degradation of the structure, increased water conveyance capacity, and prevention of siltation due to the low hydraulic resistance of the polymer sleeve. Installation is completed in the shortest possible time and does not require traffic closure or the construction of equipment access areas. Operating costs are reduced because installation and restoration of an anti-corrosion coating are not required. The warranty period for the entire scope of work performed is 6 years, with the possibility of extension based on inspection results. All components of the «PipeArm» system are manufactured in the Russian Federation. Manufacturer — TECHPOLYMER CJSC.
Certain challenges associated with applying this technology include increased qualification requirements for installation personnel (special training is required) and the use of specialised equipment during the work.
An additional option considered by the client for repairing the culvert was sleeving with fibreglass pipes. The method was developed in accordance with ODM 218.3.046–2015 «Recommendations on the technology for repairing culverts using composite materials». This method does not have the disadvantages of steel-pipe sleeving with regard to anti-corrosion coating, but it also requires the use of heavy machinery and equipment and significantly reduces the internal diameter of the structure being repaired. A fibreglass pipe is less resistant to mechanical damage than a steel pipe.
Selection of the optimal solution
Based on the results of the technical and economic comparison and the technical meeting held by the client, option No. 2 — major repair of the culvert using the «PipeArm» technology, developed by TECHPOLYMER CJSC, was selected for further design as the optimal solution.
The method used involves reinforcing the existing culvert with a reinforcing cage installed in the space between the existing culvert and the polymer protective sleeve, which is used as permanent formwork, and filling the space with a special injection compound.
The reinforcing cage consists of longitudinal and transverse reinforcement connected with binding wire. It is manufactured on site and attached to the walls of the existing culvert. The cage is designed based on the data obtained from the inspection of the structure.
The longitudinal reinforcement is secured with plastic or metal plates, which are attached to the sections of the existing culvert using metal anchors. The polymer sleeve with anchoring elements is then installed inside the existing culvert, the polymer sleeve elements are joined by extrusion welding, feed hoses for supplying the injection mixture are installed, and the system as a whole is solidified.
In 2019, in accordance with the state contract commissioned by the client, the Territorial Administration of Motor Roads of Novosibirsk Region, a contract was concluded for the major repair of the culvert at PK0+86.91 along the axis of the Novosibirsk — Krasny Yar road.
The general contractor prepared the facility for the repair work, which was scheduled to begin on 1 August 2019. A corresponding handover certificate was drawn up for the culvert to be repaired using the «PipeArm» technology. The work was performed in accordance with the design documentation, with the client’s technical supervision service continuously monitoring the work stages. The total duration of the work was 35 calendar days. Following the major repair, the culvert, ready for operation, was handed over to the client on 25 September 2019.
Following completion of the work, the client provided positive feedback on the use of the «PipeArm» technology, with recommendations for its further application.
