Causes of vibration during drilling of rotary bored piles and improvement paths

In rotary bored pile construction, the vibrations generated by rotary drilling may disturb the surrounding soil structure, induce ground settlement or hole wall collapse, and especially pose risks to adjacent buildings, underground pipelines and slope stability; at the same time, the vibrations may affect the compactness of the pile concrete, resulting in reduced construction efficiency and equipment loss. Therefore, it is particularly important to find the cause of the vibration and improve it.

I. Main causes of vibration

1. Mechanical vibration

Aging or improper maintenance of the engine, hydraulic system and transmission components lead to increased vibration during operation.

The kelly bar is too long or not rigid enough, which causes deflection during rotation and causes vibration.

2. Interaction between the drill tool and the formation

Complex formation conditions: uneven hardness and softness, rock interlayers or boulders cause sudden force changes on the drill tool.

Irrational drill tool design: asymmetric structure, severe wear or mismatched types (such as hard rock drill tools for soft soil), resulting in unbalanced forces.

3. Improper operating parameters

The feed speed, rotation speed or drilling pressure are set too high, exceeding the bearing capacity of the formation or machinery.

4. Installation problems

The base of the drilling rig is unstable and the support is insufficient, causing the whole machine to shake.

5. Drill slag accumulation

The drill slag in the hole is not cleaned in time, which hinders the rotation of the drill tool and causes impact vibration.

II. Improvement Path and Optimization Measures

1. Mechanical Maintenance and Upgrade

Regularly check the engine, bearings, hydraulic system, etc., and replace aging parts.

Use high-rigidity kelly bars or add stabilizers to reduce deflection.

2. Drill tool optimization and selection

Select the drill tool type according to the stratum (such as spiral drill tools for soft soil and toothed drill tools for hard rock).

Design symmetrical structure drill tools and replace worn parts regularly.

3. Dynamic parameter adjustment

Adjust the feed speed, speed and drilling pressure according to geological feedback to avoid overload.

Reduce parameters at the junction of soft and hard, and transition slowly.

4. Strengthen the installation of drilling rigs

Use pads and sleepers to ensure the stability of the base, and add ground anchors or counterweights.

5. Personnel training and standardized operation

Strengthen operator training and standardize operation procedures.

Develop standardized operation instructions to reduce human errors.

6. Environmental vibration control

Use isolation barriers or adjust construction periods for adjacent sensitive buildings.

Use low-vibration construction technology (such as static pile assistance).