The engineering piles are excavated mechanically to the design elevation. During excavation, care should be taken to avoid the machinery from touching the pile body, and the soil within 200mm around the pile is manually removed. For support piles, due to their dense spacing and proximity to slopes, they are excavated mechanically to a distance of 200mm from the pile, and the remaining portion is manually excavated.

　　Process:

　　1、Removal of upper concrete

　　2、Determination of elevation and cutting of protective piles

　　3、Opening of gap

　　4、Removal of reinforcement bars

　　5、Deepening of gap

　　6、Drilling of top break

　　7、Hoisting of broken part

　　8、Removal of residue

　　9、Cleaning of pile head

　　Technical Requirements:

　　1、Before the removal of the pile head, the surveyor must accurately mark the design elevation of each pile.

　　2、During construction, the construction team should densely mark around the pile base according to the markings made by the survey team, with at least four markings per pile, marked with conspicuous red paint lines.

　　3、During the pile head removal operation, in order to protect the effective pile body, a ring cut and subsequent processes should be carried out 10cm above the pile top position, reserving the final 10cm for manual chiseling to ensure the accurate height and elevation of the pile head entering the bearing platform.

　　4、After lifting the broken pile head out of the pit, the construction team should inspect each pile top to ensure its flatness. If there are any uneven areas, they should be smoothed with a steel chisel.

　　5、Before the pile head removal operation, consult with technical personnel to confirm the presence of sonic tubes inside the pile base. When removing the pile head, be careful not to damage the sonic tubes. If the sonic tubes extend too far into the pile or are too long, causing difficulty in lifting after the pile is broken, use gas welding to cut the sonic tubes. Immediately after cutting, plug the opening of the sonic tube with cotton cloth to prevent debris from falling into the tube and blocking it, affecting the pile foundation testing.

　　6、After lifting the pile head with sonic tubes out of the pit, the construction team should inspect each pile top to ensure that the sonic tubes are exposed. If they are not exposed, continue excavating the pile head until the sonic tubes are exposed. If the sonic tubes extending from the pile base are pressed down or deformed during lifting or pile head removal, they should be corrected promptly.

　　7、When the height of the bearing platform or cap beam is less than the anchorage length of the longitudinal bars, the longitudinal bars at the pile top can be raised to the top of the bearing platform or cap beam and bent into a straight hook to ensure the anchorage length.

　　The above is the information provided by the construction channel regarding the understanding of the construction process for pile head removal in geotechnical engineering. The construction channel shares more construction knowledge to help you learn construction techniques, discover the beauty of architecture, and explore the path of construction.