Vibratory rollers play a crucial role in subgrade compaction operations, and their compaction techniques directly affect the compaction quality of the subgrade and the overall stability of the project. The following are some detailed answers about the subgrade compaction techniques of vibratory rollers:
I. Preparations Before Compaction
Equipment inspection
Before conducting compaction operations, a comprehensive inspection of the vibratory roller should be carried out to ensure that all its performances are normal, especially the vibration system, transmission system and braking system.
Check whether the tires or tracks are severely worn and whether they need to be replaced or adjusted.
Material preparation
According to the material and requirements of the roadbed, select the appropriate compaction material and vibration frequency.
Ensure that the materials are evenly distributed to avoid local accumulation or loss.
Ii. Compaction Techniques
Compaction combination method
Generally, a combination of "static pressure + weak vibration + strong vibration + static pressure" is adopted. That is, first conduct a static pressure test to initially level the roadbed. Then carry out one round of weak vibration to enhance the density of the roadbed; Then, six rounds of strong vibration are carried out to achieve the main compaction effect. Finally, perform one round of static pressure to level the surface of the roadbed.
Compaction speed control
The walking speed should be controlled within 4km/h to ensure the compaction quality. Too fast a speed may lead to uneven or insufficient compaction.
Compaction sequence and direction
Follow the principle of "light first, then heavy; slow first, then fast; edge first, then center (for curved sections, follow the inner side first, then the outer side)".
Straight sections are rolled from the outside to the middle, while small-radius curved sections are rolled from the low side to the high side.
When moving forward and backward longitudinally, the front and rear wheel tracks should overlap by half the width of the rear wheel.
Adjustment of vibration frequency and amplitude
Vibratory rollers should be used with low frequency first and then high frequency. The low-frequency amplitude is large, which is conducive to deep compaction. The small high-frequency amplitude is conducive to shallow compaction.
According to the material of the roadbed and the compaction requirements, the vibration frequency and amplitude should be reasonably adjusted.
Compaction in special sections
When operating on a slope, slow down and drive slowly. It is prohibited to drive more than 20% on a cross slope. When going uphill, the drive wheels should be at the rear. When going downhill, the drive wheels are also at the back to counteract the impact force through braking.
When compacting a soft subgrade, 1 to 2 pre-rolling passes should be carried out without vibration first to make the subgrade initially level and have a certain load-bearing capacity, and then vibration should be activated for rolling.
Iii. Safety and Precautions
Operator training
Operators should undergo professional training and be familiar with the performance and operation methods of vibratory rollers.
During the operation process, safety operation procedures should be strictly followed to ensure personal and equipment safety.
Equipment maintenance
Regularly maintain and service the vibratory roller to ensure that all its performances are normal.
Replace severely worn parts in a timely manner to avoid affecting the compaction quality and equipment lifespan.
Environmental protection
During compaction operations, environmental protection should be given due attention to avoid causing pollution or damage to the surrounding environment.
In densely populated areas, dilapidated building areas and other regions sensitive to vibration, vibratory rollers should be used with caution to avoid causing damage to the surrounding environment and facilities.
In conclusion, the compaction techniques of vibratory rollers for roadbeds involve multiple aspects, including preparations before compaction, compaction techniques, as well as safety and precautions. Only by fully mastering these skills and strictly adhering to the operating procedures can the compaction quality of the roadbed and the overall stability of the project be ensured.
