Cause Analysis

1. The geological structure contains weak layers. When the pile driver hammer head passes through these layers, the weak layers are squeezed into the hole under the action of soil pressure, forming shrinkage pores.

2. In the geological structure, plastic soil layers expand upon encountering water, forming shrinkage pores.

3. The drill bit wears out too quickly and is not timely repaired by welding, thereby forming shrinkage pores.

Preventive Measures

1. Based on geological drilling data and the changes in soil quality during drilling, if weak layers or plastic soil are discovered, it is important to frequently clean the hole.

2. Regularly check the pile driver hammer head, and when wear occurs, promptly perform welding repairs. After repairing the more worn drill bits, continue to enlarge the hole to the designed pile diameter.

Treatment Measures

When shrinkage pores occur, use the drill bit to repeatedly clean the hole until it meets the designed pile diameter.