Technical Problems on Piling Construction and Solutions

There are some problems will happen occasionally during rotary drilling constructions. Common problems on rotary drilling projects and solutions are as below:

1.Piling tool jammed

Reasons of happening: 

1)In the loosen sand egg layer and flow sand layer, hole wall easily happen large area of collapse and cause piling tool jammed. 2)On time entering too deep in the clay layer, the hole wall shrinkage case piling tool jammed.

Solutions:
1)Lifting method, i.e, lift it by a crane or a hydraulic lifting machine.
2)Unclog method, i.e, clean the dregs around the drill tube by backcycling or underwater cutting, then lift.
3)Digging method, i.e, if the position of jamming is not deep, dig it and clean the dregs.

2.Main windlass wire rope breaks
The main windlass wire rope is easily breaking in case of improper operating. So the windlass rolling rope and unrolling rope should not Too violent or too loose. If the wire rope is flokkited, it should be replaced in time, to avoid breaking and cause
falling down.

3.Wearing and leakage of power head inside bush
Besides design defect, this is caused by drilling over the max designing capacity. So it should pay attention to the designed capacity of the machine, don’t operate over load.

4.Hole collapse
It’s caused by not using bentonite or use less bentonite during the drilling. To avoid hole collapse during drilling, it should keep the water level in the hole above the underground water level, and the while control the lifting and declining speed.

5.Leaking bentonite
It’s relative to the underground water level and the performance of bentonite. If big area of bentonite leaking happens, it should be backfilled. If leakage is not severe, then to adjust the performance of bentonite. It can put some concrete in the bentonite, mix them and use.

6.Drilling depth not increase
Main reasons is the drilling head being entangled by clay and causes trackslip, or there are boulder, hard scree layer or bed rock.
Measures: If it trackslips, adjust the teeth for an angle of 60°, can solve it by throwing stone into the hole, to change with a screw drill head or a pick drill head.

7.Difficult soil discharging
In some cases the mud inside the drill head is difficult to be discharged because the mud is too sticky. It can be solved by welding some holes on the drill head face.