Hydraulic Laboratory Manning's n and Grade Deviation Study for 4-Inch-Diameter Nonperforated,Corrugated Plastic Drain Tubing,

摘要

Laboratory tests were made with an 18-m (60-ft) long, 100-mm (4-in) diameter, nonperforated plastic drain tube. Probes for measuring the static head were 2.4-mm (3/32-in) diameter and placed at 1.8-m (6-ft) intervals along the tube. Tests were made for full-tube flow and free-surface flow at 0.001, 0.005, 0.01,and 0.02tube slopes. The test results are given in graphs of average velocity and discharge versus uniform depth. Manning's n was approximately 0.016. Grade deviations were studied with bends. Four bends, 2.4-m (8-ft) long,with one-and two-tube diameter offsets above and below grade,were tested. There was a significant rise in the hydraulic gradeline upstream from the bend only with bends above grade and for conditions of free-surface flow. A fine,uniform 0.2-mm mean diameter sand was used for sedimentation tests. For flow conditions with a 0.001slope and a two-diameter tube offset bend below grade,the sediment did not prevent waterflow through the bend.