To provide a ground surface drain structure for enhancing drainability of underground moisture, causing little blocking-up of a through-hole in a side wall of a drainage ditch, and preventing the outflow of soil of the ground surface around the drainage ditch in the ground surface drain structure having the water permeable side wall.
This drain structure has the drainage ditch 2 having at least one side surface formed of a water permeable porous member and a nodulizing treatment soil layer 3 driven in close contact in a side part of a side surface 2a formed of the porous material of the drainage ditch 2, and is characterized in that the nodulizing treatment soil layer 3 is formed of a material nodulized by kneading natural soil and a nodulizing agent. Thus, since water passes through the side wall 2a after being filtered by the nodulizing treatment soil layer 3, the blocking-up of the through-hole of the side wall 2a is prevented. Since the nodulizing treatment soil layer 3 is nodulized by the nodulizing agent, the layer does not flow out to the drainage ditch 2.
KOGA YOSHIKUNI
SHIKADA MASASHI