Steel sheet pile due to its special structure, it has unique advantages: high strength, lightweight, waterproof properties is good; strong durability, service life can reach 20-50 years; can be used repeatedly, and can be used for 3-5 times; environmental effect in construction can greatly reduce the amount of soil volume and concrete. Effective protection of land resources; strong disaster relief function, especially in flood control, landslides, collapse and sand disaster relief effect, particularly fast; simple construction, shorten the construction period, construction cost of more provinces.
In order to ensure the construction environment in real excavation project, but also to prevent the flow of soil, sand, piping, heave and other damage, requirements of supporting structure to have reliable isolation water system. Single sheet pile retaining structure are connected by locking plate pile, the ideal state is between steel sheet pile locking can achieve seamless occlusion completely, but usually to a steel plate pile driving convenience and rotation considerations in steel sheet pile lock mouth generally left the space of the surplus, so it is necessary for steel sheet pile seal, or by inserting depth of steel sheet pile itself to water effect, and ensures the safety of foundation pit. However, it can also set up an independent watertight system, which is the same as other plate supporting structures, which can be carried out by using high-pressure jet grouting curtain and the construction of deep mixing piles behind the lock mouth.
As for the locking and sealing effect of steel sheet pile, it is affected by many aspects, such as the shape of lock catch, the extent of locking, the corrosion of soil and water, the geological condition, etc..
In the water separation method is generally divided into artificial seal and natural seal two kinds.
In terms of artificial method, it can be divided into two kinds: before sinking pile and after sinking pile. For the sealing before piling, the sealing material is usually pre - coated on the lock hole of the steel sheet pile or pre - welded locking hole. The composition of water stop material mainly is swelling solvent elastic sealing material, and resin solvent and expansion rubber. Before the steel sheet pile is sunk, the undisturbed soil can be replaced with cement bentonite in advance and the cement bentonite can be drilled in the lock hole at the same time. In the pile can be taken after using wedge rope or rubber and plastic rope with expansive material to fill in the lock mouth; then the lock in lock seam welding, clean and impervious condition can be welded directly, if you have to lock the permeable steel cover to steel welding to complete sealed with steel or flat. In addition, a variety of water sealing measures can be taken into consideration in the case of high water stop effect.
And the natural seal is to rely on the steel sheet pile back soil sand and other fine particles or floating objects to block the lock mouth, so as to achieve the effect of water seal. For natural seals, the better the water stopping effect is, the better the particle size distribution of soil sand is. But if the back of the steel pile is water or soil particles, then it may take a long time to plug the gap. But in the actual construction process, can take certain measures to speed up the process, can be in the water by adding slag such as sealing material or pump in the foundation pit pumping speed is accelerated to form larger water level difference, it can be locked into the sealing material. In general, the natural seal needs some time, and in a wave or change pressure is relatively high, the structure of the steel sheet pile cofferdam will appear swing,Correction method of steel sheet pile so we usually don't fully use natural seal.