| 摘要 |
PURPOSE:To maintain good permeability without blocking for long periods of time by providing a gravel drain pile consisting a center packed with coarse crushed stones and a peripheral portion packed with fine crushed stones. CONSTITUTION:A gravel drain pipe 1 consists of coarse crushed stones 5 packed into the center 3 and fine crushed stones 6 packed into the peripheral side 4. The former of the pile 1 consists of an outer tube 7, an inner tube 8, a spiral blade 10 provided on the periphery of the outer tube 7, a chute 12 provided on the upper end of the tube 8, a rotary hopper 13 provided on the periphery of the tube 7, and a tip end valve 16. The tubes 8 and 7 are penetrated into the ground, the valve 16 is opened, and the tubes 8 and 7 are pulled up. Whereupon, the crushed stones 5 are discharged from the tube 8 and buried in the ground and the fine crushed stones 6 are discharged from between the tubes 7 and 8 and buried in the ground to form a pile 1. The occurrence of blocking can thus be prevented by the fine crushed stones 6 on the periphery of the pile 1, and water permeability can be raised by the coarse crushed stones 5 in the center of the pile 1. |
