Winter application plan

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1 Start date of winter construction: In accordance with the \"Regulations on Winter Construction in Building Projects\" (JGJ104-97), winter construction begins when the average daily outdoor temperature remains below 5°C for five consecutive days； Winter construction is terminated when the average daily outdoor temperature remains above 5°C for 5 consecutive days. The start and end dates for winter construction in Dalian are generally from November 14th to April 1st of the following year. The start and end dates can be determined through actual measurement, or they can be agreed upon by both Party A and Party B. 2 Technical preparatory work for winter construction 2.1 Principles for technical preparation in winter construction: 1) Ensure project quality. 　　2) Ensure safe production during winter construction ； The construction of engineering projects must proceed continuously. 　　3) The winter construction plan (measures) should be formulated in accordance with the specific time, location, and project conditions; it must be both technically reliable and economically reasonable. 　　4) It should be ensured that the required heat sources and materials have reliable supplies in order to reduce energy consumption. 　　5) Strive to minimize the number of construction sites, speed up construction, and shorten the project duration. 　　6) Projects that do not have a winter construction plan (measures) or whose preparations for winter construction have not been properly carried out shall not proceed with winter construction under any circumstances. 　　7) Effective winter construction management measures must be established. 2.2 Preparation of the winter construction plan 2.2.1 Preparatory work before formulating the winter construction plan 1) Before commencing winter construction, a thorough investigation should be carried out to obtain the necessary data: the floor area of the buildings involved in winter construction, the details of the construction project and its workload, as well as the areas that will be constructed during winter and their technical requirements. 　　2) For construction projects entering the winter period, a thorough review of the drawings should be carried out. For projects (or sections) that do not meet the requirements for winter construction, it is necessary to promptly submit requests to the project owner and the design team to modify the design. 　　3) Understand the resource supply situation in accordance with the technical requirements for winter construction. 　　4) For complex projects with high technical requirements, a comprehensive analysis of the technical feasibility of winter construction is necessary (covering aspects such as economics, energy use, project quality, and schedule). 　　2.2.2 Main contents of the winter construction plan: 1) Arrangement of production tasks and construction planning for winter construction. 　　2) The physical quantities and workload of the engineering project, the construction procedures, schedule plans, as well as the construction methods and technical measures for various sub-projects during different winter construction phases. 　　3) Heat source equipment plan (including heating heat sources and heat conversion equipment). 　　4) Plans for insulation materials and admixture materials. 　　5) Technical training for winter construction workers and labor force planning. 　　6) Key points for engineering quality control. 　　7) Winter safety production and fire prevention technical measures. 3 Preparatory work for construction in winter 3.1 Preparation of the construction site in winter 3.1.1 Preparatory work at the construction site: 1) Remove any standing water from the site, make the necessary adjustments to it, cut off sources of water that may flow into the site, and implement proper drainage measures to prevent the site from freezing due to water or steam used in construction. 　　2) After the snow on the construction site is cleared, it should not be placed near areas where mechanical and electrical equipment as well as building components are stored. 　　3) Ensure the unobstructed flow of fire roads. 　　3.1.2 Insulation of the mixer shed – The entrances and exits at the front and back of the mixer shed should be properly sealed, and heating should be provided inside the shed. Install hot water filling tanks and admixture storage containers. When cleaning the mixer, the wastewater generated must be properly drained, the sedimentation tank must be properly sealed to prevent freezing, it must be cleaned regularly, and wastewater management must ensure smooth flow. 　　3.1.3 Layout of the boiler room Before starting construction in winter, it is necessary to complete the setup of the boiler room as well as the installation of pipes. Pipelines buried underground should be laid at a depth greater than the freezing depth, while overhead pipelines should be properly insulated. 　　3.1.4 The water supply pipes, gate well, and fire hydrant well should be properly insulated. 　　3.1.5 The delivery and installation of equipment and facilities for heating raw materials, such as water mixing heating equipment and heating pits for sand. 　　3.2 Preparation of resources for winter construction 3.2.1 Stability of admixture types. Based on the type of admixture selected in the winter construction plan, along with the market supply situation, the final admixture formulation, type, and quantity are determined. 　　1) Plan for the amount of admixtures to be used. Based on the locations where the admixtures will be used and the volume of work, a plan for the required quantity is calculated and submitted to the materials supply department. 　　2) Re-testing of additives. For admixtures sold on the market, retesting should be carried out in advance to ensure that their performance meets the technical requirements. For single-component admixtures, determine the content of their active ingredients. 　　3.2.2 Preparation of insulation materials 1) Selection of insulation materials For use in winter construction, insulation materials should have good insulating properties, be inexpensive, and be available locally. Some require good fire resistance. Common insulation materials can be roughly classified according to the areas where they are used as follows: ① Insulation for steel formwork: Materials such as polystyrene foam boards and rock wool, which are lightweight, fire-resistant, and have good insulating properties, are used. 　　②Insulation covering for concrete surfaces: Use plastic films with good air-barrier properties, rock wool blankets with excellent insulating capabilities, or straw mats made from straw. (Grass mats, due to their flammability and tendency to scatter, should be wrapped in glass fiber cloth before use.) ③ Insulation for foundation trenches and pits: Use inexpensive insulating materials such as grass mats. 　　④Pipe insulation: Use perlite insulation tiles, straw ropes, etc. 　　⑤Insulation for small vehicles and mortar bucket equipment: Polystyrene foam boards and similar materials are used. 　　⑥Wind shield and greenhouse insulation: Reeds and canvas awnings are generally used. 　　⑦Insulation for door and window openings: Use plastic sheeting, curtains, etc. 　　2) Quantity and plan for insulation materials: Based on the type, specifications, number of usage cycles, and volume of work specified in the winter construction methods, the annual planned consumption is calculated, and a plan along with the date of delivery is submitted to the materials department. 　 　3.2.3 Fuel preparation for winter construction 　For winter construction, the focus is on coal for domestic use and fuel for heating purposes in construction activities, in order to meet the needs of daily life and production; preparations should be made in accordance with the requirements specified in the construction plan. 　　3.2.4 Preparation of heat source equipment 1) Installation, insulation, and trial operation of boilers and pipelines. 　　2) Installation of heat-generating components: such as the installation of steam exhaust pipes or steel strips on large formwork, as well as electric heating wires, etc ； Heaters, coal stoves, chimneys, etc. 　3) Raw material heating facilities at the construction site, such as hot water boilers, hot water tanks, and sand pits. 　　4) Installation of coal stoves or heating pipes and radiators for household use. 　　3.2.5 Preparation of construction instruments and equipment for various phases Atmospheric temperature measurement: wooden louvered boxes, maximum and minimum thermometers. 　　Additive concentration measurement: rod thermometers, electronic sensors, etc. 　　Indoor temperature measurement: wet and dry thermometer. 　　Various temperature measurements: tables and stationery. 　　4 Main construction methods and techniques for winter construction 4.1 Excavation and backfilling of frozen soil 4.1.1 Manual excavation of frozen soil 1) Excavation method: Generally, one person uses a pickaxe to dig, or a group of 3–4 people use iron wedges to break up the frozen soil. 　　2) Construction tools: There are pickaxes, shovels, 18–24 pound hammers, and iron wedges made from 450–60 gauge steel or small railway steel with flattened tips. 　　3) Key operating points: One person holds the iron wedge, while 2–3 people take turns using sledgehammers to split the frozen soil along its seams. Generally, 2–3 iron wedges are available; once the first wedge has not fully split the soil, a second wedge is placed in the crack beside it until the frozen soil is separated. 　　4) Safety measures: ① Be careful to remove the sharp edges formed by the iron wedges, to avoid injuring people. 　　②The person with the iron wedge and the person with the hammer must not be face to face; they need to be at a 90-degree angle to prevent the hammer from turning and hurting someone. 　　③When using an iron wedge, a handle made of thick iron wire or rebar should be used to prevent injury to the hand and accidental harm. 　　4.1.2 Mechanical excavation of frozen soil 1) Methods for mechanically excavating frozen soil: When the thickness of the frozen soil layer is 0.4 m or less, various types of mechanical equipment can be used for direct excavation. If the thickness of the frozen soil layer exceeds 0.4–1.2 m, the frozen soil must first be broken up using sledgehammers, after which it is loaded onto vehicles using loaders or backhoe loaders. 　　2) Based on the specific conditions such as the size, shape of the excavation area, and the depth of excavation, arrange the operating directions of excavators, loaders, crushers, etc., in a rational manner to ensure smooth transportation routes; there should be proper entrances and exits to the circular roads, so as to maximize the efficiency of various construction machinery. 　　4.1.3 Frozen soil backfilling After the construction of foundation pits, trenches, etc. is completed, it is permissible to use soil containing frozen soil particles for backfilling; however, the diameter of these frozen soil particles must not exceed 5 cm, and their proportion must not exceed 15% of the total volume of the backfill material. 　　1) Frozen soil is not allowed for backfilling inside the building. 　　2) When backfilling the trench for underground pipes, frozen soil shall not be used within a range of 50 cm above the pipe top, and the volume of frozen soil in the portion below 50 cm shall not exceed 15%. 　　3) For structures and paved roads, trench backfilling within the subgrade area must not use frozen soil. 　　4) To ensure the quality of backfilling in winter, for some major construction projects, sand can be used for backfilling if necessary. 　　5) For ground beams on frost-heaved soil and pile cap foundations, the area beneath them may be raised by the frost heave; therefore, loose materials such as cinder and slag should be used for backfilling. 　　6) All backfill areas must have standing water removed, along with ice and other debris. The thickness of each layer filled should be smaller in summer, generally not exceeding 20 cm; it should be compacted using a rammer or a roller. The area beneath the drainage ditch should be dug slightly, but not more than two-thirds of the thickness of the permafrost layer. 　　4.1.4 Foundation pit protection: After the foundation pit is excavated, insulation measures should be taken promptly to prevent the formation of frozen soil; once the inspection is successful, proceed to the next steps immediately. 　　4.2 Welding of steel bars at low temperatures In the welding work related to steel bars, when welding is carried out at ambient temperatures below –5°C, it is considered welding of steel bars at low temperatures. Welders who perform such welding must hold a certificate proving they have passed the appropriate tests for steel bar welders. Safety technical measures should be established and implemented to enhance the protection of welders at work, and to prevent accidents such as burns, electric shocks, and fires. Before welding steel rebar, trial welding must be carried out based on the construction conditions, and welding may proceed only after the trial welding is successful. The welder shall conduct a self-inspection of the visual quality of all joints after welding and discard those that are not up to standard. When welding at negative temperatures, the welding process parameters should be adjusted to allow the weld and heat-affected zone to cool slowly. When the wind force exceeds level 4, wind-blocking measures should be taken. Uncooled joints after welding should be kept away from ice and snow. Welding shall not be carried out when the ambient temperature is below –20°C. 　　4.2.1 Electroslag pressure welding of steel bars at low temperatures 1) Scope of application: Lap welding is used when the diameter of the steel bars is ≥22 cm. 2) Quality inspection ① Sampling: For visual inspection, 10% of the joints in each batch shall be sampled, with a minimum of 10 joints. For mechanical property testing, 6 specimens should be taken from each batch of finished products (those that have passed the visual inspection), with 3 subjected to tensile testing and 3 to bending testing. 　　Within the same batch, 200 joints of the same type, manufactured by the same welder using the same welding parameters, are considered as one batch. Continuous welding within a week can be accumulated. If the total number of connectors within a week is less than 200, it is also counted as one batch. By welding prestressed steel bars of equal length (including the weld joints between the screw-end rods and the steel bars), mock specimens can be fabricated according to the production conditions. 　　②Visual inspection The results of the visual inspection shall meet the following requirements: there shall be no transverse cracks at the joints. The surface of the rebar in contact with the steel bars shall show no scorching for rebar of grades ii and iii. The bend at the joint shall not be greater than 4°. The axial offset of the rebar at the joint shall not exceed 0.1 times the diameter, and shall also not be greater than 2 cm. When one connector does not meet the requirements, all connectors should be inspected to remove the defective ones. Unqualified joints can be submitted for a second inspection after being cut out and rewelded. 　　3) Precautions ① Install a voltmeter in the power switch of the welding machine to monitor voltage fluctuations. During welding, if the voltage drop exceeds 5%, the number of transformer stages should be increased appropriately ； Stop welding when the voltage drops to 8%. 　　②Before official production begins each day, two joints must be tested by welding; only after passing the visual inspection can production proceed using the selected welding method. 　　③Before welding, rust, dirt, and other contaminants must be removed from the areas where the rebar is to be welded as well as from the points where the electrodes make contact with the rebar ； The twisting and bending at the ends of the rebar should be straightened or removed. 　　④All stages of the operation process must work in close coordination to ensure welding quality; any abnormalities or welding defects should be removed promptly. 　　4.2.2 Arc welding of steel bars at low temperatures 1) Scope of application: Lap welding is used when the diameter of the steel bars is ≤22 mm. 2) Electrode selection: E43 for grade I steel bars ； Grade II steel E50 3) Pre-welding preparations ① Before welding, rust, slag, oil, and other contaminants from the areas where the steel bars and plates will be welded must be removed ； The twisting and bending at the ends of the rebar should be straightened or removed. 　　②For the lap welding of steel bars, double-sided welding is preferred; if double-sided welding is not possible, single-sided welding can be used. 　　4) Welding process: Depending on the grade, diameter of the rebar, type of joint, and welding location, the appropriate electrode diameter and welding current should be selected. During welding, a multi-layer temperature-controlled welding process is advisable, in order to prevent both too rapid cooling after welding and overheating of the joint. The welding process shall meet the following requirements: ① When performing lap welding, use two points for fixation. The tack weld shall be at least 20 mm away from the bead or the lap end. 　　②During welding, the arc should be started at one end of the overlapping rebar, and the arc should be extinguished at the end of that rebar; the crater formed should be filled in. 　　③When performing lap butt welding, the first layer of weld is started by striking an arc in the middle, and then the arc is moved toward both ends ； When welding in the vertical position, first move the arc from the center upward, then from the bottom toward the center. To achieve a certain degree of preheating for the steel bars at the joint ends. The first layer of welds should have sufficient penetration, and the main weld seam as well as the tack weld seams should fuse well, especially at the beginning and end of the tack weld seams. When welding the subsequent layers of welds, layered temperature control should be employed during welding. The interlayer temperature is controlled between 150°C and 350°C to achieve a slow cooling effect. 　　④The weld thickness h of the lap joint should be no less than 0.3 times the diameter of the rebar ； The weld width 6 shall be not less than 0.7 times the diameter of the reinforcement bar. 　　⑤When performing multi-layer welding on lap weld joints of grade II and III steel bars, the \"tempered pass welding method\" is employed, that is: the length of the final tempered pass is shortened by 4–6 mm at each end compared to the previous layers. 　　5) Quality inspection ① Sampling: Visual inspection should be carried out individually, either by visual check or measurement, after the debris from the joints has been removed. For tensile testing, three specimens are cut from each batch of finished products that pass the visual inspection to undergo tensile testing. For the high-energy champion welded joints of prefabricated structural joints, simulated test pieces can be fabricated according to the production conditions. Under on-site installation conditions, in each floor, 300 joints of the same type (same steel grade, same joint type, same welding position) are considered as one batch; if the number is less than 300, it is still regarded as one batch. 　　②Visual inspection: The results of the visual inspection shall meet the following requirements: the surface of the weld shall be smooth, with no significant depressions or weld beads. There must be no cracks at the joints. The depth of undercut, the number and size of pores and slag inclusions, as well as the dimensional tolerances of the joint, must not exceed the specified values. Joints that fail the visual inspection can be submitted for a second acceptance after being trimmed or reinforced. 　　6) Precautions for joints When welded joints are used for rebar, the welded joints located within the same member should be spaced apart from each other. Within a zone that is 30 times the diameter of the stressed rebar (with a minimum length of 500 mm), a single rebar bar shall not have more than two joints (welded joints should be used as little as possible along the entire length of the member). The percentage of the cross-sectional area occupied by joints in relation to the total cross-sectional area of the rebar shall comply with the following requirements: ① In tension zones – it shall not exceed 50% ； 　　②Compressed zone – and prefabricated structural joints – are not restricted. 4.3 Concrete Works Commercial concrete will be used for the concrete. 　　4.3.1 Material requirements for concrete 1) Cement: Portland cement or ordinary Portland cement should be used. 　　2) Aggregates: They must be free of ice and snow clumps, clean, well-graded, and hard in texture; they should not contain minerals that are prone to damage from freezing. 　　3) Mixing water: Water that has passed quality testing. 　　4) Admixtures: Use admixtures that have passed technical evaluations and meet quality standards. 　　4.3.2 Concrete mix ratio Prepared according to the concrete mix ratio provided by the laboratory. 　　4.3.3 Concrete mixing control The mixing time for concrete in winter should be increased by 50% compared to normal temperatures. 　　4.3.4 Transportation of concrete The concrete mixture should be transported to the pouring site promptly after it is mixed. During the curing process, special attention must be paid to preventing phenomena such as heat loss from the concrete, surface freezing, thinning of the concrete, loss of cement mortar, and changes in slump. 　　4.3.5 Concrete pouring 1) General requirements During concrete pouring, it is necessary to ensure the uniformity and compactness of the concrete, as well as the integrity of the structure. The dimensions must be accurate, the positions of rebar and embedded components must be correct, and the surface of the concrete after form removal should be smooth and even. 　　Before pouring, the ice, snow, and dirt on the formwork and rebar should be removed. During pouring, the mixture is discharged from mixing boards, hoppers, funnels, or various other conveying devices. Mortar can easily freeze in such containers; therefore, wind and freezing protection measures must be taken before pouring. If the concrete freezes, it should be reheated and remixed to achieve the appropriate workability before pouring again. 　　The location of construction joints should be chosen in areas where the structural shear is low and where construction is easier. Horizontal joints should be left in the columns ； Vertical joints should be provided in beams, slabs, and walls. Columns should be placed on the top surface of the foundation, high beams should be located 20–30 mm below the bottom surface of the slab, and flat slabs should be positioned at any position parallel to the short sides of the slab. The stairs should be located within the middle 1/3 of the stair length. 　　When pouring concrete at the construction joint, the cement film and loose stones must first be removed, the area should be washed thoroughly until it is moist, and the temperature of the existing concrete at the joint must be above 2°C. Then, a layer of cement paste or mortar with the same composition as that of the concrete mixture should be applied. Pouring can proceed once the strength of the concrete to be poured reaches 1.2 MPa. 　　2) Concrete pouring: The mixed concrete is poured into the formwork, and vibration is necessary to ensure its density and to allow it to fill all corners of the formwork, thereby producing components that meet the design requirements. During winter, mechanical vibration is used to vibrate the concrete; the vibration process must be carried out quickly. Before pouring, necessary preparations must be done, such as checking formwork, rebar, and embedded components, removing ice and frozen masses, setting up the scaffolding and access paths required for pouring along with checking their anti-slip measures, and preparing the vibration machinery and tools. When pouring the columns, within each construction section, the columns in each row should be poured in a symmetrical order from the outside toward the inside; it is not advisable to proceed from one end to the other, as this could cause the formwork to tilt gradually, leading to cumulative errors that are difficult to correct. 　　Beams and slabs are generally poured simultaneously, moving forward from one end. Concrete pouring for beams separately is only allowed when the beam height is greater than 1m. In such cases, the construction joint should be placed 2–3 cm below the floor surface. It is necessary to ensure proper compaction of the bottom and sides of the beam, and the vibrator must not come into direct contact with the rebar or embedded components. The thickness of the partially poured concrete layer on the floor slab should be slightly greater than that required; after vibration, it is smoothed out using a long flat trowel, after which a plastic sheet is laid over it, and a protective layer is applied promptly on top. 　　4.3.6 Curing of concrete: The heat retention method is recommended for curing: one layer of plastic film and two layers of straw bags are used for insulation. 　　4.3.7 Removal of concrete formwork 1) The time for removing the concrete formwork should be determined based on the structural characteristics, ambient temperature, and the strength achieved by the concrete; it is generally advisable to remove it gradually. 　　2) The formwork must be removed, and the concrete strength must also meet the requirements. 　　3) When removing formwork in winter, the difference between the concrete surface temperature and the ambient air temperature should not exceed 20°C. 　　4) During the removal of formwork, if signs of frost damage to the concrete are detected, the removal process should be suspended; it can resume only after the issue has been addressed. 　　5) The concrete with the formwork removed should be protected using insulating materials. Structural concrete is allowed to bear loads only after it reaches the specified strength. During construction, it must not be used under overload conditions; it is strictly prohibited to pile excessive building materials or machinery on it. 4.3.8 Measurement of concrete temperature The measurement of air temperature, raw material temperatures, and concrete temperature shall be carried out in accordance with the following provisions: 1) Air temperature should be measured 4 times per day and night, at 8, 12, 14, and 20 o’clock. 　　2) The temperature of the mixing materials and antifreeze shall be measured at least 3 times per working shift. 　　3) The temperature of the concrete mixture exiting the mixer shall be measured at least once every 2 hours. 　　4) The temperatures before pouring and after vibration completion shall be measured at least every 2 hours. 　　5) Measurement of concrete temperature during curing: Before final setting, measurements are taken every 2 hours for the first three days; thereafter, measurements should be taken twice per day and night. 　　6) After the curing period has passed, the concrete temperature can be measured periodically in case of significant changes in air temperature. 　　7) To measure the temperature inside the concrete, some temperature sensors with one end sealed should be embedded during concrete pouring, and they should be covered immediately to protect them from external temperatures. The thermometer should remain inside the tube for 5 minutes before being taken out, after which the temperature should be recorded promptly. 　　8) The temperature measurement holes should be placed in areas where the concrete temperature is low and representative. 　　9) All temperature measurement holes shall be numbered, and a layout diagram of the temperature measurement holes shall be prepared. The temperature monitoring personnel should also check the insulation coverage, and be aware of the date of concrete pouring, the curing period, as well as the allowable minimum temperature for the concrete. If any problems are detected, the relevant personnel should be notified immediately so that measures can be taken promptly to enhance insulation or apply localized short-term heating. 　　4.3.9 Concrete specimens and strength testing: The sampling rate for specimens, or the maximum volume of concrete that can be represented by a set of specimens, shall comply with the provisions of Article 4.6.4 of the \"Code for Construction and Acceptance of Reinforced Concrete Structures\": 1) At least one set per working shift. 　　2) At least one set per 100 m3 of concrete poured. 　　3) For cast-in-place floors, there must be at least one set per floor. 　　Furthermore, during winter construction, it should also be taken into account that for beams and frames, a sample should be retained for every 50 m3 of concrete poured. Each batch of test pieces shall consist of at least 4 groups, which are pressure-tested at –28 days, upon form removal, after +28 days, and at the time of delivery for use. It’s best to prepare several more sets as spare test pieces. Strength test specimens shall be made at the construction site using concrete mix for cast-in-place structures, and cured under the same conditions as the structure or components. 　　5 Training for winter construction workers Training for construction workers: Organize relevant professionals to study the theories, standards, regulations, and construction techniques related to winter construction. 　　6 Safety Management for Construction in Winter Safety regulations and procedures must be followed during winter construction, and safety management should be carried out in accordance with the following aspects. 　　6.1 Safety education for winter construction 1) All employees must receive regular technical safety training. Conduct safety and technical briefings in advance of winter construction in line with the project requirements. Equip yourself with proper safety gear. 　　2) Workers must receive safety education as well as training on operating procedures: Those who change their job roles or temporarily participate in production activities also need to receive safety education and safety briefings. 　　3) Workers in special occupations (including those in electrical work, scaffolding, lifting, boiler operation, welding, blasting, machinery, vehicles, etc.) must receive professional training from the relevant departments and obtain a certificate after passing assessments before they can carry out their tasks. A review is conducted once a year. 　　4) Use new equipment and new tools. The new process should provide operators with safety technical instructions regarding mechanical properties and operating methods. 　　5) All construction organization designs and construction plans for projects must include safety technical measures. For tasks such as blasting, trenching, formwork erection, and scaffolding construction, a separate technical safety plan (also known as a safety design) must be prepared and thoroughly explained to the workers; construction is not permitted otherwise. 　　6.2 On-site Safety Management 1) The storage areas for various materials, components, concrete elements, acetylene cylinders, oxygen tanks, etc., as well as the acetylene handling stations on site must meet safety requirements, and strict management should be implemented. 2) During trench construction in winter, slope protection measures should be specified in the plan based on the soil conditions and characteristics of the project; it is necessary to check the stability of the slopes during construction and after thawing, and immediate action should be taken if cracks appear, the soil becomes loose, or the slope protection piles become deformed. 　　3) Strengthen seasonal labor protection measures. During winter, it is necessary to take measures to prevent slipping, freezing, and gas poisoning. Scaffolding, access walkways, and areas that need to be used must have anti-slip measures in place. Clean it up promptly after frosty weather. Inspect the scaffolding promptly after heavy snowstorms to prevent falls from heights. 　　6.3 Electrical Safety Management in Winter 1) The construction plans for winter work and the scheduling of construction activities must include floor plans showing the location of electrical circuits on site. An electrician should be on site to handle the installation, maintenance, and management of electrical equipment. It is strictly prohibited for non-electricians to modify it without permission. 　　2) The use of bare wires is strictly prohibited at the construction site. Wires should be laid in a way that protects them from being crushed or damaged, and to prevent them from freezing in ice and snow. After a heavy snowstorm, power lines should be inspected to prevent electric shock accidents caused by broken wires. 　　3) To raise the temperature of the construction environment using electric heating equipment, a \"plan for preventing high-voltage electricity from entering the building\" should be prepared. Electrical equipment is equipped with dedicated switchgear boxes. The plugs for high-voltage and low-voltage power sources should be separated to prevent accidents caused by accidental operation. 　　6.4 Ending safety management after winter construction Winter construction can be terminated once the temperature rises and negative temperatures do not occur for seven consecutive days and nights. But note the following points: 1) The stability of the soil slope in deep pits should be monitored at all times, and a dedicated person should be responsible for such monitoring. Fill the soil back as soon as conditions permit. 　　2) For high scaffolds and external elevators set up during winter construction, as well as scaffolds over three stories in height, tower cranes, roadbeds, utility poles, etc., a comprehensive inspection should be carried out to prevent tilting or collapse caused by freeze-thaw settlement of the foundation. 　　3) For masonry constructed using the freeze-thaw method, necessary measures shall be taken during thawing in accordance with the provisions of the masonry construction acceptance specifications. 4) 　The material storage areas and the large formwork storage areas should be inspected and organized. Prevent stacks, mounds, and components from collapsing due to freezing and thawing in the soil layer.