Quality assurance measures during the construction of foundation works
1. Construction sequence and process flow:
Excavation, drainage→ concrete cushioning→ reinforcement binding
Pile and foundation beam concrete pouring → masonry foundation wall → backfill earth →± more than 0.00 main body construction
2. Earthwork excavation
(1), the level point and control pile in the construction area must be properly protected, if necessary, add a protective pile or set up with concrete, before the excavation, the gantry pile must be inspected, retested, and the construction process must not be arbitrarily collided or piled on it.
(2) Before the earthwork construction, the operator shall be handed over in writing and verbally to the operator of the operation method, quality standards and safety procedures in the construction plan, and the implementation should be checked at any time during the construction process, and if it is found that there is a violation, it should be corrected immediately.
(3) In the process of excavation, the plane position, slope slope and elevation are measured to check whether they meet the design requirements.
When mechanical excavation, manual cooperation, because the excavation depth is not large, the earth excavation step in place, excavation, in order to prevent mechanical damage to the original soil, leave 150mm thick, the use of manual clearance. After the excavation of the earth, the relevant personnel are invited to conduct the foundation trench inspection in time and do a good job of recording the trench inspection.
3. Drainage of foundation pits
Drain the pit, use a pump to pump water out of the drainage ditch outside the foundation pit.
4. Concrete cushion layer
(1), the foundation excavation by the designer, supervision, Party A and other relevant personnel acceptance, the solid concrete cushion layer, before the cushion layer first do a good job of the high point, the cushion soil must symbolize the actual requirements, must try to ensure that the base has no water, the grade of sand and gravel should meet the requirements, mix evenly, lay the thickness in line with the design requirements.
(2), before the concrete cushion layer is set to control the elevation point, while pouring the edge with a flat vibrator vibration, the surface is flat with a wooden maple maple, the surface flatness is required to be within ±8, after the maintenance reaches a certain strength, the axis is ejected and the steel bar is lashed.
(3), the chiseling of the pile head: according to the design elevation around the pile to do a good job of marking, when away from the marking line 300, it is not allowed to be chiseled with a sledgehammer, only allowed to be chiseled with a small hammer, to ensure the quality of the pile body and the pile head into the bottom plate or pile 100.
5. Basic concrete and formwork engineering
(1), the pile adopts brick blank mold, the illustrated size of the brick blank is constructed according to the large sample drawing, the size shall not be modified at will, and the surface of the brick blank mold shall be painted with 1:2 mortar.
(2) The foundation beam formwork adopts plywood, the formwork is made according to the requirements of the wood mold reproduction, and the vertical mold is constructed according to the template reproduction detailed drawing. To ensure the reliability of the formwork and support and have sufficient strength and stiffness, the materials used in the formwork project must be carefully checked and selected, and materials that do not meet the quality requirements must not be used, and the construction of the formwork project should be simple, easy to operate, strong and durable, and easy to transport and repair
(3) During construction, first loft the bullet line, pop out the outer wheel line of the engineering structure according to the drawing, and also pop up the installation line or inspection line of the formwork, the construction axis, the elevation line, and the geometric dimensions must be correct.
(4) Before the construction of the formwork, the site is required to be clean and flat, and all the buried parts and holes must be checked and accepted, and after confirming the accuracy, please ask the supervising engineer to accept the visa.
(5), formwork construction, must be strictly in accordance with the pop-up line construction, to ensure that the component axis size, structural elevation, geometric size is accurate, the vertical mold is strictly according to the vertical mold to turn the detailed drawing construction, to ensure the reliability of the formwork, support, if there is an impact on the formwork construction should be rectified in time, vertical structure of the steel bar and pipeline first with the shelf temporary support, so as not to cause the template to run position
(6) All adjustable formwork and support systems shall not be arbitrarily changed after the acceptance of the template.
(7) Precautions for pouring concrete
a. Vibrator insertion point plum-shaped insertion, spacing of about 300-500. When vibrating, it is necessary to "quick plug" and "slow pull" to prevent the concrete surface from vibrating first, while the concrete below is delaminated, segregation and prevents fast pulling, and the concrete is too late to replenish, leaving space. After the vibrator is inserted into the concrete, it should be twitched up and down, with an amplitude of 5-10cm, to remove the air in the concrete.
b. When vibrating, the surface of the concrete is no longer sinking horizontally, no bubbles no longer appear, and the mortar water on the surface should be about 20-30S.
C. The vibrator rod should not be close to the template when vibrating, and the vibrator should be avoided as much as possible from colliding with the template and steel bar, and the embedded parts should be buried to prevent running mold and steel displacement.
d. When the concrete is poured in layers, when the upper layer of concrete is pounded, it should be inserted into the next layer of about 50mm to eliminate the seam between the two layers. After pouring concrete, the exposed steel bar must be cleaned at any time, and the cement slurry that falls on the concrete and its formwork heel should be cleaned up in time
