| 摘要 |
<p>Drainage system which involves digging a trench (1) 1m or more deep and approximately 25cm. wide, with a small rounded groove (1 a) in the bottom. A 5cm diameter pipe (2) containing a large number of holes is placed over the groove. This pipe is preferably made of plastics with transverse channels containing the holes (4). These channels give the pipe flexibility as well as making it resistant to the pressure of soil. A strip of perforated felt (5) or other porous material, slightly narrower than the trench, is placed over the pipe and the trench is then filled in. The weight of soil presses the felt around the pipe. Water permeates through the felt into the pipe via the holes (4), but the felt prevents the holes from becoming blocked with particles of soil.</p> |
