(1) The diameter of the pilot hole should not exceed 0.9 times the diameter of the pipe pile, and measures should be taken to prevent the collapse of the hole, and the depth of the pilot hole should not exceed 12m;
(2) It is advisable to use long auger drill hole, long auger drill can drill through strongly weathered granite layer, high strength hard interlayer or isolated stone, vertical deviation should not be greater than 0.5%;
(1) The diameter of the pilot hole should not exceed 0.9 times the diameter of the pipe pile, and measures should be taken to prevent the collapse of the hole, and the depth of the pilot hole should not exceed 12m;
(2) It is advisable to use long auger drill hole, long auger drill can drill through strongly weathered granite layer, high strength hard interlayer or isolated stone, vertical deviation should not be greater than 0.5%;
(3) When the pilot hole needs to pass through the hard sandwich, the pilot hole diameter should be pile diameter D-20mm; When the pilot hole enters the weathered rock with higher number of hits, the equal diameter pilot hole can be used;
(4) The pilot hole should enter 1m of the bearing layer to reduce the squeezing effect, and the pilot hole diameter should be D-50mm of the pile diameter;
(5) For the situation of “careful use of site” of pipe piles such as inclined bearing layer, thin non-weak soil layer and obvious soil squeezing effect, the construction method of pilot hole should be combined with the type of site, pile driving method and pile tip form to determine the construction measures.
Note: Pre-drilling (pilot hole) is a common measure used in pipe pile construction to penetrate hard interlayers and isolated stones, reduce the squeezing effect, and increase the depth of the pile. According to the engineering experience and actual situation, the diameter of the pilot hole should be determined according to the soil condition of the site, pile diameter, pile density and other factors, the pilot hole diameter can generally be 10cm or 5cm smaller than the pipe pile diameter, if necessary, it can also be equal diameter pilot hole. Under normal circumstances, the depth of the pilot hole should not exceed 12m, considering that the vertical deviation of the pilot hole is not easy to control when the pilot hole is too deep, it is difficult to correct the deviation when the pilot hole is skewed, and it is easy to break the pile body. When the pilot hole enters the weathered rock with higher number of hits, it should be noted that even if the pilot hole diameter is large (pile diameter D-20mm), it may still be difficult to drive the pile to the bottom of the hole (that is, “hanging pile”). If necessary, equal diameter pilot holes can be used; When water is accumulated in the pilot hole, it is advisable to use the open-mouth pile tip. If the sealed pile tip is used, the unfavorable situation of hanging pile may occur.
(3) When the pilot hole needs to pass through the hard sandwich, the pilot hole diameter should be pile diameter D-20mm; When the pilot hole enters the weathered rock with higher number of hits, the equal diameter pilot hole can be used;
(4) The pilot hole should enter 1m of the bearing layer to reduce the squeezing effect, and the pilot hole diameter should be D-50mm of the pile diameter;
(5) For the situation of “careful use of site” of pipe piles such as inclined bearing layer, thin non-weak soil layer and obvious soil squeezing effect, the construction method of pilot hole should be combined with the type of site, pile driving method and pile tip form to determine the construction measures.
Note: Pre-drilling (pilot hole) is a common measure used in pipe pile construction to penetrate hard interlayers and isolated stones, reduce the squeezing effect, and increase the depth of the pile. According to the engineering experience and actual situation, the diameter of the pilot hole should be determined according to the soil condition of the site, pile diameter, pile density and other factors, the pilot hole diameter can generally be 10cm or 5cm smaller than the pipe pile diameter, if necessary, it can also be equal diameter pilot hole. Under normal circumstances, the depth of the pilot hole should not exceed 12m, considering that the vertical deviation of the pilot hole is not easy to control when the pilot hole is too deep, it is difficult to correct the deviation when the pilot hole is skewed, and it is easy to break the pile body. When the pilot hole enters the weathered rock with higher number of hits, it should be noted that even if the pilot hole diameter is large (pile diameter D-20mm), it may still be difficult to drive the pile to the bottom of the hole (that is, “hanging pile”). If necessary, equal diameter pilot holes can be used; When water is accumulated in the pilot hole, it is advisable to use the open-mouth pile tip. If the sealed pile tip is used, the unfavorable situation of hanging pile may occur.
Post time: Sep-06-2024