Two technical methods to improve the bearing capacity of rotary drilling pile
Currently, the commonly used technical methods to improve the vertical bearing capacity of cast-in-place pile include the bottom expansion method and the post-grouting method for bored pile.
Bottom Expansion Drill Bucket Method
In the same stratum, the pile end resistance is directly proportional to the bottom area of the pile. Under the premise of constant pile diameter, increasing the bottom area of the pile can significantly enhance the end bearing capacity. Therefore, using a bottom expansion drill bucket to enlarge the size of the pile hole bottom, forming a pile with a smaller top and a larger bottom, is an effective technical method to improve the vertical bearing capacity and pullout resistance of a single pile.Reliable rotary drilling auger,bucket and casing will greatly improve your construction efficiency
Most of the rotary drilling machines in Japan are equipped with oil pipe racks related to the bottom expansion drilling bucket. The use of bottom expansion piles can save 50% of concrete, and therefore 95% of pile holes in Japan are bottom expansion piles.
Post-grouting Method
This method can effectively eliminate the hidden danger of sediment at the pile bottom, strengthen the pile body, densify the soil around the pile, and improve the bond strength between the pile and the surrounding soil, thereby enhancing the bearing capacity of a single pile by 30 to 90% generally.
The effect of the post-grouting process is that the injected cement slurry combines with the sediment at the pile bottom to form concrete, eliminating the impact of the sediment.
The cement slurry fills the "virtual tip" and "dry slag" formed due to segregation, improving the concrete strength at the pile tip.
The post-grouting at the pile bottom densifies the soil, and the cement slurry penetrates into the soil to form a consolidated mass, enhancing the strength of the soil and thus improving the end bearing capacity of the bored pile.
Injecting high-pressure grout can create upward prestress at the pile bottom, which is beneficial for end-bearing piles.
The high-pressure grouting on the side of the pile has a compaction and densification effect on the soil around the pile, penetrating into the soil to form bamboo-shaped grout bubbles. This creates a bamboo pile effect, enhancing the friction resistance on the side of the pile.
After drilling the pile hole, the reinforcement cage is placed, and a grouting pipeline is preset. Concrete is then poured into the pile body, and grouting is performed after it solidifies. Before grouting, a water injection test is conducted to confirm the smoothness of the pipeline. Grouting is first performed on the side of the pile, followed by the bottom. Group injection is done before group grouting.More drilling skill and piling foundation information focus on LIMTA Piling Machinery.
