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2017WinterShotcreteEMag

2016 Outstanding Underground Project Rehabilitation of the Suhurlui Irrigation Pipeline By Calin Mircea, Ofelia Corbu, Eugen Maier, and Cristian Rus The Suhurlui Irrigation Pipeline is located in the southeast of Romania, Galati county, in the vast planes formed by the Danube river, 50 miles (80 km) upstream of the river’s discharging point into the Danube Delta and 90 miles (150 km) from the Black Sea. The pipeline is part of a larger irrigation system that supplies water to roughly 195,000 acres (75,000 hectares) of agricultural land, the largest single irrigated plot in the country. The Suhurlui Irrigation Pipeline is made of two parallel steel pipes spaced 100 ft (30 m) apart, and constructed from 1984 to 1986 by welding 20 ft (6 m) steel segments. The nominal diameter of the pipes is 10 ft (3.05 m), with a wall thickness of roughly 0.4 in. (10 mm). The Suhurlui Irrigation Pipeline is supplied with water pumped from the Danube river (the largest river in Europe) and transported via open canals for roughly 28 miles (45 km) until entering the underground pipeline where the terrain slopes severely. The pipeline follows the natural topology of the terrain and is buried at depths from 6.5 to 16 ft (2 to 5 m) along its 2.2 mile (3.6 km) length, crossing under a road and a river. CHALLENGES Since its initial commissioning in 1986, exposure of the steel shell to groundwater, through a failure in external waterproofing, led to severe damage to the pipeline. The steel pipe wall reduced in thickness and was eventually pierced, leading to heavy water losses of roughly 40% of the total irrigation water transported. An additional cause of the steel deterioration was the 110 kV power line that runs parallel to the pipeline that induced significant electrical corrosion. The geotechnical survey revealed the groundwater table started at roughly 1.5 ft (0.5 m) below grade, which created a significant risk of floating if the pipes were emptied without loading them with extra weight. Other particular challenges were raised by the position of the pipes at a 30-degree angle for roughly 500 ft (150 m) along a steep hill descend, as well as a road and a river undercrossing where the pipes descended further into the ground. PROJECT SPECIFICATION AND CAD SIMULATIONS Artifex Engineering Ltd. conducted the detailed technical design, including three-dimensional (3-D) modeling of the pipeline before and after the shotcrete job. Given the requirement for extending the service life of the pipes for a minimum of 15 years, the only feasible solution was determined to be to create a new reinforced concrete jacket inside the existing pipe by shotcrete placement. View of one of parallel pipes of Suhurlui Irrigation Pipeline 42 Shotcrete | Winter 2017 www.shotcrete.org


2017WinterShotcreteEMag
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