What Problems Do Horizontal Directional Drilling Rigs Usually Encounter When Working?

When the hole body deflects and bends during horizontal directional drilling, the causes should be analyzed and handled. Generally, the drill cone can be hung at the deflection to sweep the hole repeatedly to make the drilling straight; When the deviation is serious, the clay shall be backfilled to the deviation, and the drilling shall be carried out after the sedimentation is dense. Paste drilling and buried drilling often occur in rotary drilling and percussive drilling in positive circulation (including submersible drilling rigs). In this case, check and calculate the mud consistency, drilling slag inlet and outlet, drill pipe inner diameter, and slag removal equipment, and control the appropriate footage; If the drill has been seriously stuck, stop drilling, put out the drill cone and remove the drilling slag. When drilling and dropping objects, it is advisable to quickly fish with fishing forks, hooks, rope sleeves and other tools. If the falling body has been buried by sediment, the mud and sand should be removed according to the above items, so that the fishing tool contacts the falling body before fishing.

When horizontal directional drilling opportunities include hole expansion and shrinkage, measures should be taken to prevent hole collapse and excessive swing of the drill cone. Shrinkage is caused by excessive wear of drill cones, untimely welding repair, or due to soft soil, clay and mudstone swelling in the formation when encountering water. The former should pay attention to timely welding repair of drill cones, and the latter should adopt slurry wall protection with low water loss rate. When shrinkage has occurred, it is advisable to sweep the hole up and down repeatedly with a drill cone to expand the hole diameter. Sticking often occurs in percussive drilling. After sticking the drill, it is not suitable to lift it forcefully, but only gently. When it cannot be lifted gently, use a small impact drill cone to impact or use the method of punching and suction to loosen the drilling slag around the drill cone before lifting it.

After the hole collapse occurs, the cause should be found out and corresponding measures should be taken, such as maintaining or increasing the water head, removing heavy objects, eliminating vibration, etc., to prevent the hole from continuing to collapse, and then use the mud suction machine to suck out the soil that has collapsed into the hole. If the hole does not continue to collapse, the normal pouring can be resumed. If the hole collapse is not serious, it can be backfilled above the hole collapse position, and measures such as improving the mud performance, increasing the water head, and burying the pile casing can be taken to continue drilling. In case of serious hole collapse, the borehole shall be backfilled with sand or small gravel mixed with clay immediately. After a period of suspension, the cause of hole collapse shall be found out and corresponding measures shall be taken to re drill. When the hole collapse position is not deep, the method of deep burying the pile casing can be adopted to tamp the soil around the pile casing and re drill the hole. The cause of hole collapse may be water leakage around the bottom of the pile casing, the water level in the hole decreases, or in the tidal river, when the tide rises, the water level difference in the hole decreases, the original hydrostatic pressure cannot be maintained, and the hole collapse may be caused by the stacking of heavy objects around the pile casing or machine vibration. During the pouring process, if it is found that the slurry level in the well casing slurry suddenly rises and overflows the casing, and then plummets and bubbles appear, it should be suspected that it is a sign of hole collapse, which can be detected with a sounding hammer. For example, if the sounding hammer was originally suspended on the concrete surface and is buried and cannot be lifted, or the sounding hammer cannot reach the original depth when detecting the concrete surface, and there is a lot of difference, it can be confirmed that it is indeed a hole collapse.