How to properly handle the rotary drilling rig when it is in the quicksand layer?
Solving the problem of hole collapse mainly lies in preventing the formation of initial hole collapse and the vicious circle of continuous hole collapse, namely, the prevention is more important than the rescue in solving the hole collapse problem.
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Reasonably mix the mud. According to the characteristics of the flow plastic stratum, high-viscosity and medium-weight mud should be configured for wall protection.
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Ventilation holes should be set on the drill bit to ensure the mud flow up and down during the drilling rod lifting process and prevent the vacuum phenomenon from occurring.
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The mud level should be kept 2-3 meters above the groundwater level, which can be achieved by raising the pile casing or setting up a clay dam around the hole.
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Adjust the operation mode: control the mud level and keep it 30-40cm away from the upper edge of the pile casing during the drilling process (especially during the drilling rod lifting). When drilling into soft soil and sand layers: soft soil and sand layers are prone to hole collapse. During operation, try to reduce the erosion and disturbance to the hole wall, and strictly follow the "three slow" principles: slow lifting and lowering of the drill, and slow drilling speed. By strictly controlling the movement speed of the drilling tools, the disturbance of the mud to the hole wall can be reduced, and sufficient time can be left for the formation of mud skin. Observation on the ground: always pay attention to the mud level.
When it is found that the mud level suddenly drops and a large amount of foam gushes out, it can be judged that there is a local collapse. Drilling should be stopped immediately, and the drill bit should be slowly lifted with the bucket bottom open to prevent secondary collapse caused by disturbance. Accident treatment of local collapse: when local collapse is found, continue to inject mud into the hole and lift the drill bit. Dump enough clay into the hole with an excavator, and then lower the drill bit to reverse and compact the clay. Continue to reverse while compacting. After stabilization, drill in with the method mentioned above.
