EXCAVATION HEAD FOR PILE HOLE AND EXCAVATION METHOD FOR PILE HOLE

摘要

Even when a foreign object such as gravel appears, it is not caught in the excavation head and does not interrupt the excavation work. The digging hole drilling head 30 is constructed by attaching excavating arms 15 and 15 to the horizontal shafts 12 and 12 of the head main body 1 so as to freely swing. The fixed excavating blades 10 and 10 of the length H ₁ are fixed to the lower face 6a of the head main body 1 with the interval W ₁ therebetween. The female excavating blades 24 and 24 of length H ₂ are fixed to the lower end 15a of the excavating arm 15 with a gap W ₂ therebetween. To the pre-ground investigation, if not to a foreign substance such as a pebble of a maximum particle diameter (D ₀₎ is present, "length (H ₁₎ and the distance (W ₁₎ D ₀ of the fixed drilling edge 11", "Rock Excavation And the length (H ₂ ) and the interval (W ₂ ) D ₀ of the blade 24 are satisfied. The distance L _{1 in} the horizontal direction between the tip 25 of the female excavating blade 24 and the tip 11 of the fixed excavating blade 10 is larger than the distance D ₀ between the tip 25 of the female excavating blade 24 And the distance h _{1 in} the vertical direction of the distal end 11 of the fixed excavating blade 10 D ₀ .