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Sharing of the drilling method of rock-socketed pile with rotary drilling rigs and roller bit core barrel

2024-07-20

I. Features of the drilling method


1. The tools used in this method are basically the same as those required for the original steel grain and alloy drilling, except that the rock crushing tool - the drill bit is replaced, and a weighting device is added. It can be promoted and used in general rock-socketed pile construction sites.
2. Easy to operate and widely adaptable. It can be used for both non-circulation drilling and reverse circulation drilling. Production workers can master the operation technology after short-term training.
3. This method crushes rocks evenly and has high efficiency. The construction cost is low compared to alloy drilling, and the hole quality is good.


II. Scope of application


This method is suitable for the construction of rock-socketed pile holes with a pile diameter of less than φ1500mm and a relatively flat rock surface.


III. Process principle


1. When the roller bit works at the bottom of the hole, it revolves around the kelly bar column and rotates around the center axis of the roller bits. Its rotation is in the form of rolling, and the running resistance is small, so it can withstand a large drilling pressure.
2. When the roller bit contacts the rock at the bottom of the hole, the alloy inserts on the palm of the bit have a small contact area with the rock (forming a fulcrum contact), which makes it easy to obtain a higher unit axial pressure, which is conducive to crushing the rock.
3. When the roller bit rotates at the bottom of the hole, in addition to the axial pressure of the drill string, it is also subjected to the impact load caused by the change in the center height of the cone during rotation, which improves the rock crushing effect.
4. When the palm of the bit rolls at the bottom of the hole, the rock is crushed alternately, each working time is short, and the wear rate is low, which is conducive to improving the life of the drill bit.


IV. Process Flow


1. Alloy drill bits are used for pile hole opening and covering construction, and the construction is carried out according to the rotary drill cast-in-place pile construction procedure.
2. When the alloy drill bit is used to construct to the strongly weathered rock layer 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 depth and the rock debris of the bedrock is fished out in the backwashing fluid at the pile hole mouth, after the on-site supervisor agrees to the hole completion, the hole can be cleaned, the steel cage and guide tube are lowered, the hole is cleaned again, and underwater concrete is poured to form the pile.
4. After the roller bit core barrel is lifted, the rock debris and sediment in the protective barrel should be removed in time, and the wear of the cone palm, support point and flange should be checked. If there is any damage, it should be repaired in time for use.
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