Preparation and regulations for construction of reinforced composite piles

I. General Provisions

1The construction of bulk stiffened composite pile and flexible stiffened composite pile should comply with the current industry standard "Technical Code for Building Foundation Treatment".JGJ79The relevant provisions of.

2The construction of rigid and rigid composite piles shall comply with the following provisions:

(1) When concrete precast piles, steel piles or cast-in-place piles are used for rigid composite piles, they shall comply with the current industry standard "Technical Code for Building Pile Foundations".JGJ94The relevant provisions of;

(2) When cement fly ash crushed stone pile is used for rigid and rigid composite pile, it should comply with the current industry standard "Technical Code for Building Foundation Treatment".JGJ 79The relevant provisions of.

3Before the construction of the reinforced composite pile, the pile forming process test shall be carried out, and the number shall not be less than3The root. When the pile quality cannot meet the design requirements, it should be tested again after adjusting the parameters related to design and construction.

4The allowable deviation of each single pile position in the reinforced composite pile should be soil10mm.The allowable deviation of perpendicularity of elastic composite pile should be 1%, the allowable deviation of perpendicularity of loose rigid composite pile, flexible rigid composite pile and ternary composite pile should be0.5% .

Second, construction preparation

1The following information should be available before the construction of the reinforced composite pile:

(1) geotechnical engineering investigation report, building layout plan, pile layout plan and technical requirements;

(2) Product qualification certificate and sampling inspection report of raw materials such as sand, stone, cement, lime, fly ash and steel;

(3) Test data of sand and stone ratio, cement-soil ratio and concrete ratio;

(4) Qualified certificates of precast concrete square pile, prestressing pipe pile, steel pile and other finished pile products and on-site sampling inspection data;

(5(experimental construction materials;

(6) data of plane and elevation points;

(7Type, distribution and structural quality of adjacent buildings and underground facilities;8Special construction scheme.

2Before construction, the site should be levelled and removed above and underground obstacles. When the surface soil is soft, it should be rolled and tamped;The site plane elevation should be measured after site leveling, and the design elevation above the pile top should be reserved 300mm～500mmThe soil.

3Before pile positioning, axis positioning points and leveling points should be set according to a single building (structure), and measures should be taken to protect them. Post construction piles should be relocated.

4Before construction, the working performance of construction machinery and equipment and the intact degree of various measuring devices should be checked.

Three, the construction process

1In the construction of loose and flexible composite pile, it is advisable to construct loose pile first and then construct flexible pile.

2The following process can also be used for the construction of loose and flexible composite pile:

(1) premix process:The sand and cement are premixed before piling on site;

(2) sand before powder process:The powder jet pile machine is used to spray dry fine sand and then cement powder into piles.

(3) powder before sand process:Firstly, cement powder is sprayed and then dry fine sand is sprayed and mixed into piles.

(4) double spray process:Cement powder and dry sand are sprayed into the soil from two spouts and mixed into piles.

3,In the construction of composite pile, it is advisable to use the same pile machine in situ to construct the bulk pile first and then the rigid pile. When the soil layer is soft, it is advisable to adopt the technology of rebeating or expanding the bottom of scattered pile.

4In the construction of non-rigid composite pile, the pile pipe can be sunk to the design depth, then placed into precast concrete pile, and the scattered material is poured around it, and the pile is formed after drawing out the pipe.

5In the construction of flexible and rigid composite pile, it is advisable to construct flexible pile first and then rigid pile. Rigid pile construction should be after flexible pile construction6hOnly.

6In the construction of ternary composite pile, it is advisable to play loose pile first, then play flexible pile to form loose and flexible composite pile, and then build rigid pile in loose and flexible composite pile. The construction of rigid pile should be after the construction of loose flexible pile6hOnly.