Long spiral drilling pumping super fluid concrete rear reinforced cage technology is evolved by the Japanese CIP engineering method, it is different from ordinary drilling pile, it adopts special long spiral drilling machine drill to the predetermined depth, through the hole, to the pile top, and then insert the reinforced cage and the formation of the pile, is a new type of pile foundation construction means. Super fluid concrete cast-in-place pile is widely used, not limited by the groundwater level, the concrete liquidity is strong, aggregate dispersion is good, the screw drill can drill and press concrete, easy operation, concrete pouring speed is fast, good pile quality, reduce the cost. It is one of the top ten technologies promoted by the Ministry of Construction in 2005.

2 Characteristics of working law

2.1 Super fluid concrete liquidity is good, stones can be suspended in the concrete without sinking, will not produce segregation, easy to put into the steel cage;

2.2 There is no empty soil in the pile tip, which prevents the common construction problems such as broken pile, diameter shrinkage and hole collapse, and the construction quality is easily guaranteed;

2.3 Strong ability to wear hard soil layer, high bearing capacity of single pile, high construction efficiency and easy operation;

2.4 Low noise, no disturbance to the public, no need for mud wall protection, no sewage discharge, no soil squeezing, civilized construction site;

2.5 High comprehensive benefit, and the project cost is relatively low compared with other pile types.

2.6 The design method of the dry-in-hole bored pile is adopted, and the design calculation index of the dry-in-hole bored pile (the index value is greater than that of the mud wall bored pile and less than the precast pile).

3 Scope of application

This method is applicable to the construction (structure) foundation pile and foundation pit, deep well supporting pile, applicable to fill soil layer, silt soil layer, sand soil layer and pebble layer, and also applicable to all kinds of soil layer with groundwater, can be pile under bad geological conditions such as soft soil layer and quicksand layer. The pile diameter is generally 500mm~800mm.

4 Principle of process

Super fluid concrete cast-in-place pile is drilled by the long screw rig drill to the design elevation. After the drilling, the concrete hole set in the inner pipe drill is pressed to fill the super fluid concrete to the top elevation of the design pile, and remove the drill pipe to press the steel cage into the pile. When the concrete is pressed to the pile top, the concrete poured should be 50cm above the pile top to ensure the strength of the concrete on the pile top.