Sharing of construction methods for drilling rock-socketed piles with tricone bits of rotary drilling rigs
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1. Characteristics of construction method
1. The tools used in this construction method are basically the same as those required for the original steel and alloy drilling, except that the rock crushing tool-the drill bit has been replaced, and a weighting device has been added. Generally, rock-socketed pile construction sites can be promoted and used.
2. Easy operation and wide adaptability. Both non-circulation drilling and reverse circulation drilling are possible, and production workers can master the operation technology after short-term training.
3. This construction method has uniform rock fragmentation, high efficiency, low construction cost relative to alloy drilling, and good hole quality.
2. Scope of application
This construction method is suitable for the construction of rock-socketed pile holes with a pile diameter within φ1500mm and a relatively flat rock surface.
Three, process principle
1. When the cone palm is working at the bottom of the hole, it revolves around the drill pipe string and rotates around the axis of the tooth palm. The rotation is in the form of rolling, and the running resistance is small, so it can withstand greater drilling pressure.
2. When the roller cone bit（tricone bits） is in contact with the rock at the bottom of the hole, the contact area between the alloy inserts on the tooth palm and the rock is small (to form a fulcrum contact), and it is easy to obtain a higher unit axial pressure to facilitate the crushing of the rock.
3. When the cone rotates at the bottom of the hole, in addition to being subjected to the axial pressure of the drill string, it is also subjected to the impact load caused by the change in the height of the cone center during rotation, which improves the rock crushing effect.
4. When the palm inserts roll at the bottom of the hole, the rock fragmentation alternates. The working time is short each time and the wear rate is low, which is beneficial to improve the life of the drill bit.
Fourth, the process
1. Use alloy drill bits for pile hole opening and cover soil construction, and follow the construction procedures of rotary drilling cast-in-place piles.
2. When the alloy drill bit is used to construct the strong weathered rock or hard rock layer, the drill can be lifted and replaced with a suitable roller bit to drill to the depth required by the design.
3. When the construction reaches the required degree of exploration and the cuttings of the bedrock are recovered from the flushing fluid on the pile orifice, after the site supervisor agrees to finish the hole, it can be transferred to the hole cleaning, lowering the steel cage, the lower pipe, and the second time. Clear holes and pour underwater concrete into piles.
4. After the roller bit is lifted, the cuttings and sediment in the bucket should be removed in time, and the wear of the roller palm, supporting point and flange should be checked. If damaged, it should be repaired in time for use.
