I. Basis for compilation
Code for Winter Construction of Building Engineering (JGJ- 104-97)
Code for Acceptance of Construction Quality of Concrete Structure Engineering (GB50204-20XX)
Regulations on Management of Technical Data of Building Engineering (DB 15/427—20XX)
Safety regulations for geotechnical engineering and technical specification for application of concrete admixture (GB50 1 19-20XX).
II. General rules
(1) During the winter construction, seriously implement the national technical and economic policies, respond to the winter construction requirements of the construction project, be technologically advanced, economical, reasonable, safe and applicable, and ensure qualified quality, safety and reliability, and timely completion. This winter construction plan is specially formulated.
(2) winter construction period division principle
Due to the different construction sub-projects, winter construction has different requirements. The start and end dates of winter construction are: when winter comes, if the daily average temperature for five consecutive days is stable below 5℃, the first day of this five days is the beginning of winter construction; When the temperature gets warmer, the average daily temperature in the last five days is stable above 5℃, then the last day of these five days is the whole day of winter construction (when the average outdoor daily temperature is stable below 5℃ for five consecutive days, winter construction will be started immediately; When the outdoor daily average temperature is stable at 5℃ for five consecutive days, the winter construction will be terminated).
(3) Basic principles to be followed in winter construction
1. Ensure the engineering quality and production safety;
2. Winter construction measures should be economical and reasonable, and try to reduce the increased cost;
3. Reliable sources of heat energy and materials should be considered in winter construction, so as to reduce energy consumption and shorten the construction period as much as possible.
Third, the characteristics of winter construction
(1) Winter construction is the season with frequent engineering quality accidents due to unfavorable construction conditions and environment.
(2) The concealment and lag of quality accidents.
(3) The planning and preparation of winter construction is time-consuming and the technical requirements are complicated.
Fourth, the winter construction site
According to the actual situation and construction period of this project site, CFG pile engineering of retaining wall is considered as the second case of winter construction.
Verb (abbreviation of verb) Winter construction preparation
(A) organizational preparation for winter construction
The project department set up a leading group for winter construction, which is responsible for organizing production technology quality, safety management and winter construction material supply, coordinating and organizing winter construction work, clarifying responsibilities, ensuring that all work is carried out in a timely and effective manner during winter construction, and avoiding the production schedule, engineering quality and safety construction being affected by poor organization of winter construction work. Before entering the winter construction, certain measures should be taken to meet the construction requirements and prevent the sudden first frost and cold current from damaging the concrete. The organization of winter construction leading group is as follows:
Team leader:-
Members:-,-,-
(2) Production preparation for winter construction
The project department should complete the preparations for the construction site before entering the winter construction date, so as to avoid the losses caused by the early cooling. We should pay close attention to the weather change to prevent the influence of the early cold current on the strength of structural concrete. Site preparation includes:
1. The water supply pipeline at the construction site shall be insulated and protected against freezing in advance. The horizontal pipeline should be buried deeply, and the vertical pipeline should be wrapped with thermal insulation material to prevent the pipeline from freezing and affecting production; Remove underground obstacles and surface water, level the site and roads, and ensure the smooth flow of fire roads; Check mechanical equipment and temporary facilities, maintenance and insulation; The maintenance of the maintenance, don't have to repel the site in time, do a good job of antifreeze construction machinery.
2. Organize the construction personnel to seriously study and be familiar with the winter construction contents in the winter construction specifications and acceptance specifications, and make technical disclosure in combination with the winter construction scheme, so that the winter construction scheme can be implemented to people.
3. Arrange special personnel to collect weather forecast, measure temperature and report any abnormal situation immediately; And strengthen the construction site and concrete temperature measurement.
4. Conduct a comprehensive inspection on water supply, power supply, anti-virus and waterproof measures of the whole construction site to eliminate hidden dangers.
3) Preparation of winter construction materials
1. Fire insulation materials (rock wool, striped cloth, fire curtain, plastic sheet, flame retardant straw curtain, quilt, etc. Used for thermal insulation and fire prevention of construction operation surface and surrounding environment).
2. Measuring instrument for winter construction: thermometer (used to measure concrete temperature and air temperature).
3. Commercial concrete (try to add early strength agent and antifreeze).
4. antifreeze for construction machines and tools and lubricating oil used in winter.
(4) Technical preparation for winter construction
According to the characteristics of the site, an effective winter construction scheme is compiled, and a reasonable construction method is selected to ensure the safety of winter construction and realize the civilized construction on the winter construction site. Organize the examination and approval of winter construction scheme, and make disclosure of construction scheme step by step.
1. Written disclosure with commercial concrete mixing station:
1) concrete outlet temperature (not lower than 10℃) and tank outlet temperature (not lower than 5℃).
2) When concrete is mixed with negative temperature additives, different negative temperature additives should be used according to different temperature conditions, and special tests and technical appraisal must be conducted by relevant units before use.
3) When the average temperature of winter construction is lower than -5℃, the comprehensive heat storage method is generally adopted. The early strength antifreezing admixture used has the factory certificate, and it is officially used after the contrast test of the laboratory block. The comprehensive heat storage method should choose ordinary portland cement or R-type early strength cement above R32.5.
4) Admixtures should be powdery composite admixtures which can obviously improve the early strength and reduce the critical strength of frost resistance, and should be added together with aggregates to ensure uniform mixing.
5) The slump of concrete shall be 18 ~ 22 ㎝.
2. Winter construction personnel training. Through training, winter construction management personnel can understand the winter construction tasks and characteristics of this project, make overall arrangements for the labor force in the process of organizing production, make timely preparations for winter construction, and avoid quality accidents or shutdown caused by sudden temperature changes. Construction management personnel must master the following work points through training and scheme disclosure:
1) Understand the weather forecast of the day and do a good job of temperature measurement.
2) Check the implementation of winter protection measures for divisional and sectional works.
3) Check the implementation of winter safety measures.
4) If problems are found in winter construction, feedback information in time.
5) Atmospheric temperature measurement measures and records the highest and lowest temperatures in a day from the beginning to the end of winter application.
6) Selection of admixture: Commercial concrete is adopted in this project, and the quality certificate and test report of commercial concrete admixture are mainly checked.
7) The comprehensive heat storage method is adopted for thermal insulation and curing of concrete.
Six, winter construction technical measures
(1) Bury building construction control points, leveling points and axis positioning points to prevent soil frost heaving and construction vibration.
(2) When welding negative temperature steel bars outdoors in winter, the ambient temperature is lower than -20℃, and the joints that are not cooled after welding are strictly prohibited from touching snow, ice and water. When steel bars are used under negative temperature conditions, inspection should be strictly strengthened during construction, and collision and scratch should be prevented during transportation and processing.
(3) Strictly control the temperature of concrete entering and leaving the tank not lower than -5℃, and the slump of concrete meets the construction requirements of cast-in-place piles.
(4) The concrete test block shall be made according to the routine, and sent to the curing room for curing after form removal.
Seven. Site layout
Where winter construction is carried out, the site must complete all the preparatory work before the official start of construction, and the construction can be started only after the winter construction conditions are met. According to the physical workload, organize relevant machines and tools and thermal insulation materials to enter the site in advance, and do a good job of thermal insulation and antifreeze for the temporary water supply pipeline on site.
Eight, winter safety civilization construction measures
(1) Safety fire prevention measures
1. Before entering the winter construction, the safety fire control measures shall be disclosed to the workers.
2. Conduct safety and fire prevention education for employees, implement measures for fire prevention, gas poisoning prevention, anti-skid and anti-freezing in winter construction, and implement them to construction teams and individuals.
3. Before entering the winter construction, the equipment, heat source equipment, heating equipment and temporary equipment used in the winter construction shall be inspected and accepted for safety.
4. Strengthen the management of flammable thermal insulation materials on site and clean up flammable materials in time.
5. Do a good job of fire water source and equipment insulation, make it in good use.
6. Strengthen the management of on-site fire source, lock the power switch and control box, and assign special personnel to take charge of management to prevent electric leakage and electric shock.
7. In case of contact with steam source and hot water during construction, it is necessary to prevent burns.
(2) Electrical fire prevention measures
1. Ensure the safety of electricity consumption in key fire prevention parts, and set fire extinguishing equipment suitable for electrical fire in densely populated areas on site.
2. A safe distance should be kept between the lighting and combustible materials. Ordinary lamps and lanterns should not be less than 300mm, spotlights and iodine tungsten lamp should not be less than 500mm, and combustible materials should not be directly irradiated. When the spacing is not enough, heat insulation measures should be taken.
3. When a fire occurs in the electric welding operation, the welder should immediately cut off the power supply, and cover the fire with sand or use a carbon tetrachloride fire extinguisher or a carbon dioxide fire extinguisher to extinguish the fire. Do not use water or general acid-base foam extinguisher, otherwise there may be danger of electric shock.
(3) Electrical safety protection measures
1. Electrical pipelines laid underground should be completed before winter construction to ensure laying quality and electrical safety.
2. It is forbidden to use electric furnace heating; It is forbidden to pull wires indoors, and measures should be taken to limit the on-site electricity consumption, so as to ensure that lines and equipment are not overloaded and prevent fire accidents.
3. Set up an electricity inspection team to strengthen the safety management of temporary electricity consumption. If you check and urge the users of the electric mattress, you must turn off the switch and unplug it before going to work; It is forbidden to install high-power lighting in the dormitory (1kw iodine tungsten lamp); Put an end to ever-burning lamps, etc.
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