In order to help relevant personnel understand the relevant contents of rotary excavation pile foundation, Zhong Da Consulting has compiled relevant materials, and the basic contents are as follows:
What is rotary excavation pile foundation?
Engineering terminology generally refers to the pile type constructed by rotary drilling rig, which is the full name of rotary drilling cast-in-place pile, and is referred to as rotary drilling pile in engineering. Because of mechanical operation, the number of workers is not high, which can save a lot of labor costs.
Key points of rotary excavation pile foundation engineering construction technology;
(1) pore formation. When drilling with rotary drilling rig, the specific gravity and viscosity of mud will be adjusted reasonably according to the soil conditions. In order to avoid hole collapse and give full play to the role of hole wall, bentonite is usually used to make slurry. When drilling a hole, the soil can be stirred, and different soil clays have different specific gravity. The specific gravity of mud should be controlled according to the actual construction to keep it at a certain specific gravity.
(2) hole cleaning. In the construction of pile foundation engineering, hole cleaning is particularly important, mainly to remove the drilling slag deposited at the bottom of the hole and ensure that the concrete can directly contact with the bearing stratum rock, thus ensuring the quality and bearing capacity of pile foundation. During hole cleaning, the lifting hammer is stirred up and down in the hole, and mixed mud is injected at the same time to neutralize the mud and drilling slag in the hole. Then, the neutralized mud and drilling residue are pumped back to the mud sedimentation tank by the mud pump through the mud return pipe for sedimentation. The precipitated mud is separated from sand and drilling residue by cyclone, and the separated mud is injected into mud tank to be pulped again with bentonite, caustic soda and cellulose. During hole cleaning, the on-site quality inspector should observe the density of displacement mud in time, and pour concrete in time after reaching the standard. It is forbidden to deepen the hole depth instead of cleaning the hole.
(3) Fabrication and placement of reinforcing cage. The first is to make reinforcing cages, and the spacing between main bars, stirrup spacing and diameter of reinforcing cages should be strictly controlled. After the production of reinforcing cage is completed, it will be accepted section by section, and it will be put into storage after it is qualified; Next, place the reinforcing cage. After the steel bar is welded, it should always be vertical, align with the hole position and enter the hole, do not collide with the hole wall, and always maintain a light and stable state.
(4) Concrete pouring. In order to ensure the construction quality of concrete pouring, the following requirements should be met: (1) choose a conduit with a moderate length, and the distance between the bottom of the conduit and the bottom of the hole is 30 ~ 50cm；; Ensure the tightness of the catheter; Concrete pouring should not be interrupted, but should be done in one go; Uniformly mixed concrete should ensure the success of the first batch of back cover; In the process of pouring, records should be made first to avoid the interruption of pile formation in the process of lifting the catheter.
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