Laboratory Evaluation of Artificial Envelopes of Subsurface Drainge Producted in Iran and Comparing With Other Similar Foreign

Difficulties like production, transportation , performance and etc in sandy envelopes which have been used in subsurface drainage projects have innovated artificial envelopes At this research performance of the artificial envelope PP450 produced in two Iranian factories (called A and B) came under close observation and compared with the same foreign grade. For these reasons first with Komo Standard Tests the artificial envelope came under loading process and the amount of sand passed into every artificial envelope measured. Results of soil/sand tank showed the out flow fluctuation on the first second and third day was high but it decreased after that and got stable (94, 66, 72((mlit/min)/m) respective related to the foreign envelope , envelope A and envelope B). Total maximum and minimum average of the out flow discharge related to the foreign envelope and the envelope A.Comparison of water resistance around the drainage pipe showed that the foreign artificial envelope has the minimum entrance resistant(2.03 day/m). Minimum and maximum amount of sediment in the pipes related to ,putting in order, the foreign envelope and envelope A. but in sum there was no major difference on the amount of sediment, the maximum difference 20% is its indication.Finally this research passes and confirms the envelopes produced inside but recommends more study on them , specially envelope A, in order to get a better quality.