Steel casing is a round barrel with both ends open, made by wrapping iron sheets around a hole pile of a certain size. It is generally 20 to 40 cm larger than the pile diameter. The burial depth depends on the soil characteristics. The deviation in plane position should not exceed 5 cm, and the inclination should be less than 1%.
The steel casing is a hollow, cylindrical bucket with both ends open, made by wrapping iron sheets around a hole pile of a certain size. It is generally 20-40cm larger than the pile diameter and the burial depth is determined by the soil characteristics. The deviation in the horizontal position should not exceed 5cm, and the inclination should be less than 1%. It can stabilize the hole wall, prevent cave-ins, isolate surface water, guide the drill bit, secure the pile position, and protect the original working surface, etc.
Basic requirements for steel casing:
1. Bury the protective sleeve under accurate layout, adhering to the methods and requirements for its installation. If drilling is conducted on land, the general approach is to use the excavation method, which is relatively simple and straightforward.
2. The installation of steel casing is the starting point for the construction with a rotary drilling rig. The flat position and verticality of the steel casing should be accurate, and the surrounding area and the base of the casing should be tight and impermeable. During the installation of the steel casing, a layout should be made using the control piles for positioning, marking the drill rig's drill point at the bottom of the hole. Then, hoist the steel casing into the hole, locate the center of the steel casing, and use a cross line at the top or bottom of the casing. Move the steel casing to align its center with the drill rig's drill point. Simultaneously, check for verticality using a level or plumb bob. Afterward, symmetrically and uniformly backfill the casing with clay of optimal moisture content, ensuring it is compacted in layers to achieve optimal density. This ensures the verticality and prevents slurry loss, displacement, and collapse. If the soil at the base of the casing is not clayey, it should be excavated deeper or replaced. After backfilling and compacting 300-500mm thick clay at the bottom of the hole, place the casing to prevent leakage and collapse at the bottom opening. During backfilling, prevent the steel casing from tilting. The top of the casing should be tied with wooden planks to吊紧 symmetrically, preventing it from descending.
Steel casing construction method features:
1. Steel pipe casing installation
2. By utilizing conventional equipment, controlling the mud properties, and reasonably selecting drilling parameters, we have increased the hole boring speed, effectively preventing wall collapse and diameter reduction, maintaining wall stability, controlling the pile hole shape, and achieving ultra-long pile construction.
3. During the hole-making process, while drilling the桩钢护筒， we consistently employ interlocking anti-deviation techniques to ensure high verticality of the pile holes, facilitating the smooth installation of the steel cage and normal construction of adjacent piles.
4. Improved the conventional hole cleaning process by adopting a one-time cleaning before drilling and a two-time cleaning before concrete pouring, along with gradual adjustment of mud properties. This has enhanced the hole cleaning efficiency and ensured that the sediment at the bottom of the hole meets the specifications and design requirements. At the same time, it also guarantees the stability of the pile hole before concrete pouring and the smooth pouring of underwater concrete.
5. Improve the underwater concrete grouting process while ensuring concrete quality, to guarantee the strength of the pile concrete, the fullness between the concrete and the soil around the pile, and the integrity of the pile.
