FIELD INVESTIGATIONS OF WATERTIGHTNESS OF CONCRETE LINED CANAL IN FILLING SECTION

Аннотация

The main objective of the ponding test of the constructed section was to check water tightness and durability of the work completed. The quality of the work assessment has to be determined by filling the selected canal section to its maximum water level and check the behavior of canal embankment during the water retention period. The factors which influence the quality assessment of the canal embankment are to check leakage of water through the embankment. The leakage through the canal embankment is possible if the geomembrane has not been properly placed and have been punctured, the quality of the concrete is poor, the joints have not been filled properly, and seaming of geomembrane has not been done properly. A canal section of 50 m has been selected as a trial section for the ponding test to achieve the objectives. The filling data collection and surveillance started from May 30, 2020 to June 05, 2020 for a period of seven days. During the seven days in addition to the leakage observation, the weather data has been collected for the purpose of calculating the Evaporation losses. During the period of 7 days no leakage or seepage or wet area has been observed on the outer side of the canal embankment on both the banks of canal. It is evident from the physical observations that the quality of work carried out is satisfactory and sand embankments are stable. The geomembrane is watertight and performing its designed function. The water level in the canal has been decreased due to the loss of evaporation, the weather data observed daily for the calculation of evaporation has been shown in the tables on the following pages. The average loss due to evaporation has been 25.7 mm/day.