After the foundation pit is backfilled, the steel sheet piles shall be removed for reuse. Before pulling out steel sheet piles, the sequence of pile-pulling methods, pile-pulling time, and soil hole treatment should be carefully studied. Otherwise, the ground subsidence and displacement will be caused by the vibration of the piles and the excessive soil of the piles, which will bring harm to the constructed underground structures and affect the safety of the adjacent original buildings, buildings, or underground pipelines. Therefore, it is very important to try to reduce the amount of soil in the piles. At present, the measures of irrigation and sand irrigation are mainly used.

(1) Pile pulling method

Vibrating hammer piles can be used in this project: use the forced vibration generated by the vibrating hammer to disturb the soil quality, destroy the cohesion of the soil around the steel sheet piles to overcome the resistance of the piles, and rely on the additional lifting force to pull them out.

(2) Matters needing attention when pulling piles

a. Starting point and sequence of pile pulling: For closed steel sheet pile walls, the starting point of pile pulling should be more than 5 away from the corner piles. The starting point of pile pulling can be determined according to the situation during pile sinking, and the method of jumping and pulling can also be used if necessary. The order of pulling out piles is preferably the opposite of that of pile driving.

b. Vibrating and vibrating pulling: When pulling out piles, you can first use a vibrating hammer to vibrate the lock of the sheet pile to reduce the adhesion of the soil, and then pull out while vibrating. For sheet piles that are difficult to remove, first, use a diesel hammer to vibrate the pile down 100~300mm, and then vibrate and pull it alternately with a vibratory hammer.

c. The crane should be gradually loaded with the start of the vibrating hammer, and the lifting force is generally slightly smaller than the compression limit of the shock absorber spring.

d. The power supply for the vibratory hammer is 1.2~2.0 times the rated power of the vibratory hammer itself.

(3) If the steel sheet pile cannot be pulled out, the following measures can be taken:

a. Hit it again with a vibrating hammer to overcome the resistance caused by the adhesion to the soil and the rust between the bites;

b. Pull out the piles in the opposite order to that of the sheet piles;

c. The soil on the side of the sheet pile bearing the soil pressure is relatively dense, and another sheet pile is driven in parallel near it, so that the original sheet pile can be pulled out smoothly;

d. Grooves are made on both sides of the sheet pile, and the Peronite slurry is put in to reduce the resistance when pulling out the pile.

(4) Common problems and treatment methods in steel sheet pile construction:

a. Tilt. The reason for this kind of problem is that the resistance between the piling and the adjacent pile lock is relatively large, while the penetration resistance in the direction of the piling is small; the treatment methods are: use instruments to check, control and correct at any time during the construction process; Pull the pile body, drive it while pulling it, and correct it step by step; reserve a moderate deviation for the sheet pile driven first.

b. Reverse. The reason for this problem: the lock is a hinged connection; the treatment methods are: lock the front lock of the sheet pile with a clamp in the direction of piling driving; set a pulley bracket in the gap between the two sides of the sheet pile to stop the sheet pile Rotation during sinking; on both sides of the hasp at the lock of the two sheet piles, fill them with pad iron and wooden tenons.

c. A total connection. The cause: the steel sheet pile is tilted and bent, which increases the resistance of the notch; the treatment methods are: correct the tilt of the sheet pile in time; temporarily fix the adjacent piles that have been driven with angle iron electric welding.