Bored Pile Drilling – What is Impact Drilling?
1. When drilling, mud should be poured into the hole first. If there is water in the hole, the clay can be put directly into the hole, and the impact cone is used to repeatedly impact with small strokes to make slurry.
2. During hole opening and the entire drilling process, the water level in the hole should always be kept 1.5 to 2.0m higher than the groundwater level and 0.3m lower than the top surface of the casing. Water should be replenished in time after removing the slag.
3. When impacting the silt layer and clay layer, the drill bit should use a medium stroke (1.0~2.0m) impact. When impacting the sand layer, small pieces of stone and clay should be added and impacted repeatedly with a small stroke (0.5~1.0m) to strengthen the wall protection. When the boulder and hard rock layer is used, the heavy hammer should be replaced with a small stroke (1.0~2.0m) impact. When impacting in a rocky formation, if the diameter of the ballast emerging from the hole is between 5 and 8 mm, it indicates that the mud concentration is appropriate. If the particle size of the ballast that emerges is small and small, it indicates that the mud concentration is insufficient. Qualified mud can be extracted from the pulping tank and entered into the circulation.
4. When impact drilling, the operator must release the main wire rope in time according to the speed of the footage, so that the wire rope is always in a tight state during each impact. It cannot be released less or more. If it is released less, the drill bit will not fall to the bottom of the hole and the hammer will be empty. Not only will the footage not be obtained, but it may cause the wire rope to be interrupted and the hammer to drop. If you put too much, the drill bit will tilt toward the hole wall after falling to the bottom of the hole, hitting the hole wall and causing hole expansion.
5. In any case, the stroke should not exceed 6.0m. In order to correctly increase the stroke of the drill cone, a length mark should be made on the wire rope.
6. Adjacent pile holes in deep water or with poor geological conditions must not be drilled at the same time.
