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Rig Reasons for the short pile head of the rotary drilling rig
Rotary drilling rigs will have some problems due to the changeable construction site. Today I will talk about the reasons and preventive measures for the short pile head. The elevation of the top of the pile is insufficient. First, the construction control is not strict, and the concrete stops when the design elevation is not reached. Pouring; the other type, although the mark is as high as the design value, the pile top elevation is insufficient after the pile top is removed due to the thick concrete floating layer. Near the end of the pouring, the slurry is too thick, it is difficult to determine the slurry or concrete surface with the sounding hammer, or the probe hammer is too light to sink to the concrete surface, and misdetection occurs, so that the pipe is pulled out to terminate the pouring and cause short Pile head accident. When the concrete is poured, the hole wall collapses without being noticed, and the sounding hammer or sounder probe cannot reach the surface of the concrete. This situation is the most dangerous, sometimes a few meters short. Prevention and treatment measures for short-filled pile heads in rotary drilling rigs:
1. Pay attention to whether there are signs of hole collapse during the filling process. If there is a hole collapse, it should be handled according to the aforementioned methods before refilling.
2. The sounding hammer shall not be lower than the gravity and shape specified in the specification. For example, the gravity of the sounding hammer shall be used for the bored pile with relatively high mud density. The heavy hammer may sink into the concrete tens of centimeters even when the concrete slump is still large. The consequence of the wrong sounding is that the depth of the pipe buried in the concrete surface is more than tens of centimeters than the actual; and the slump of the first batch of concrete At the later stage of pouring, it will become smaller and smaller, and the depth of the heavy hammer into the concrete will become smaller and smaller, and the sounding can still be accurate.
3. At the end of pouring, add clear water to dilute the mud and take out part of the sedimentation soil. Use thermistor or induction probe depth sounder. Using the iron box sampler to determine the suspicious horizon sampling.
For the treatment of short pile heads in rotary drilling rigs, please refer to the aforementioned extension protection tube according to the specific conditions; or add a protection tube inside or outside the original protection tube, press it into the poured concrete, and then extract water, remove slag, and pour Ordinary concrete; or use high-pressure water to loosen the mud and soft layer, and then use a suction machine to suck up the mud on the surface of the concrete, and then pour underwater concrete into the pipe.Rig