1. Safety precautions for working in high temperature days
1. Arrange work and rest time reasonably, avoid high temperature periods, and seize the construction while the morning and evening are cooler.
2. In summer, safety helmets should be worn in strict accordance with the requirements for high-temperature open-air operations.
3. Employees should learn the knowledge of safe construction in summer and master the relevant prevention and protection skills.
4. In the high-temperature work place in the closed (semi-enclosed) space, appropriate measures should be taken to do a good job of ventilation and cooling to avoid heat stroke.
5. In high temperature weather, the pressure vessel should be treated with high temperature and sun protection.
6. Pay attention to personal hygiene and do not eat unclean food in high temperature in summer; Prevent mosquito bites and seasonal diseases.
7. In summer, the construction weather is hot, and there are many situations where you wear slippers and go to work shirtless, which should be strictly prohibited and strengthened to check the correct use and wearing of labor protection equipment.
8. Fire prevention measures should be taken in summer construction, and oxygen acetylene bottles should strictly abide by the safety operation procedures and do a good job of sun exposure during use.
1
Rebar construction
1. It is strictly forbidden to stack steel bars at will, and transportation and stacking should be arranged uniformly.
2. Waterproof and rust-proof measures should be taken in the steel processing plant and the semi-finished product stacking place at the construction site.
3. When stacking, the wood should be padded at the bottom to prevent water from causing rust to the steel bar.
4. In rainy weather, cover the geomembrane with the steel bars and check whether the geomembrane is leaking.
5. It is strictly forbidden to pile on the excavated plain soil, which is easy to make the square wood fall into the soil, so that the steel bar and the soil are in direct contact, resulting in the corrosion of the steel bar.
6. In outdoor construction in summer, it is strictly forbidden for workers to directly touch the steel bar with their bare hands when carrying the steel bar, so as not to cause burns.
7. When the steel bar is tied, take protective measures.
2
Construction formwork
1. When the construction formwork is stacked in summer in a centralized manner, fire-fighting equipment should be placed in the site to avoid fire caused by dry temperature.
2. When the materials are stacked in a centralized manner, personnel should be arranged to conduct special inspections, and there should be no open flames on the site.
3. The construction formwork, beam, and wall formwork must be left with a cleaning port or water outlet, and the formwork release agent should be covered with plastic cloth in case of rain after brushing, so as to prevent the isolation layer from being washed away by rain.
4. If the steel pipe frame material is supported on the backfill, the sleepers and backing plates should be padded, and the firmness and stability of the formwork and support should be checked in time after the rain, and whether there is any change in the cross-sectional size of the formwork.
5. The wooden formwork used in rainy days should be flattened after removal to avoid deformation and cleaned up in time.
6. Concrete should be poured as soon as possible after the formwork is assembled to prevent the formwork from being deformed in the sun and rain. If the concrete cannot be poured in time after the formwork is assembled, and it is drenched by rainwater, the concrete should be re-inspected before pouring to strengthen the formwork and support.
7. Formwork and components: the stacking site is hardened, and the plug should be firm. Before pouring concrete after rain, the formwork and support should be carefully checked to prevent the formwork support from loosening.
8. When the large formwork lands, the ground should be solid and firmly supported.
9. After the formwork and square timber used in the main structure are dismantled, they are hoisted to the designated material yard in time to prevent the formwork and square timber from being exposed to the sun and rain.
3
Concrete construction
1. Mix ratio adjustment
In order to reduce the loss of concrete slump and avoid the concentration of hydration heat, the adjustment of the mix ratio should fully consider the loss of slump. The raw material can be adjusted to choose cement with low hydration heat, and the setting time of concrete can also be delayed by adjusting the amount of composite admixture to meet the construction requirements.
2. Mixing and transportation of concrete
Effective measures should be taken to control the concrete mixing temperature when mixing concrete in the hot season. The concrete mixing temperature is reduced by using low-temperature water mixing, using cool water to rinse the aggregate, and taking measures to control the temperature of cement entering the machine.
(1) In summer, pour cool water on the concrete transport body to avoid the heat of the steel tank from entering the concrete, resulting in an increase in the temperature of the concrete. Before each concrete construction, each concrete conveyor truck required to be constructed should be moistened with water to cool down, so as to avoid the water in the concrete from evaporating due to high humidity and reducing the construction quality of the concrete.
(2) In the process of concrete transportation, the road should be kept flat and unobstructed, and the concrete should maintain its homogeneity during transportation, and it should not be stratified or segregated when transported to the pouring site, and it should have the required slump and gas content.
(3) The concrete for pumping construction is used, and the pump pipe is required to be wrapped with felt, and water is regularly sprinkled on the surface of the pump pipe to reduce the temperature increase of the pump pipe due to sunlight and concrete friction, and avoid the loss of concrete collapse and the occurrence of pipe blockage.
(4) When pouring concrete, pay attention to pumping water and mortar to wet the pump pipe. The transportation capacity of concrete transportation equipment should adapt to the needs of the setting speed and pouring speed of concrete, and ensure that the pouring process is continuous.
3. Pouring of concrete
(1) Strengthen the temperature observation during construction to avoid temperature cracks.
(2) Take appropriate temperature control measures:
Reduce the pouring temperature, pay attention to the sunscreen of aggregates in the specific construction, add ice chips or ice water to stir the concrete, and cover the container in transportation to prevent sun exposure;
Reduce the heat rise of hydration, select reasonable raw materials, and adopt a good mix ratio to reduce the amount of cement;
In order to prevent surface cracks, measures can be taken to increase the surface temperature of the concrete, such as covering the exposed surface of the concrete structure with insulation, erecting insulation sheds and covering with plastic film.
(3) To pour a large volume of concrete, a cooling water pipe (serpentine pipe) can be buried in the structure and cooled by circulating water.
4. Concrete curing
Concrete poured in summer, if not properly maintained, will cause concrete strength to decrease or plastic shrinkage cracks appear on the surface.
(1) After the completion of the finishing operation or the initial setting of the concrete, the curing shall be carried out immediately, and the sprinkling curing method shall be adopted for continuous curing. In the first 7 days after the concrete is poured, the concrete should be in a fully wet state.
(2) After completing the prescribed curing, it is best to provide a moist covering layer on its surface when removing the film.
(3) The water for concrete curing must be tap water or a qualified water source, and sewage or acidic water shall not be used. The number of sprinkling should be measured in the wetness of the concrete surface.
(4) If manual sprinkling and spraying are used for maintenance, the concrete surface can be covered (wrapped) tightly with absorbent materials such as geotextiles, sacks, cotton felt, etc., and the interval between sprinkling and spraying is short. Moisture should be retained inside and outside the cover from beginning to end to prevent wet and dry cycles. Generally speaking, the curing water temperature should not be lower than 15°C, and the difference between the curing water temperature and the surface temperature of the concrete should not be higher than 15°C to prevent cracks on the concrete surface.
(5) If the concrete surface is wrapped with plastic film for moisturizing and curing, the plastic film should have a certain crack resistance, tensile strength, and flexibility. After the concrete is demolded, it should be sprinkled with water on the surface of the concrete first, and immediately wrapped tightly, and the plastic film should be close to the surface of the concrete, without leakage and ventilation.
During the curing period, water beads will appear on the surface of the concrete from beginning to end. In order to keep the concrete surface wet, water can be sprayed into the plastic film at regular intervals, and the integrity of the film should be checked frequently. If it is found that there is a phenomenon such as plastic film disconnection and rupture, it should be repaired in time.
(6) According to different meteorological and temperature conditions and different structural characteristics, the curing period of high-performance concrete should generally be controlled within 14~28 days. During this curing period, thermal insulation curing measures should be adopted to ensure that the curing humidity of concrete meets the requirements, so that the hydration of concrete can be carried out smoothly.
Second, the key points of construction supervision and control in windy weather
Protective measures to be implemented by the supervisor:
1. Do a good job in advance of the hidden danger investigation of the temporary facilities such as prefabricated prefabricated houses, enclosures, and simple masonry sheds, and evacuate relevant personnel immediately if they are found to be in danger to prevent casualties caused by collapse. Strengthen the safety education of operators and improve their awareness of prevention.
2. Strengthen the monitoring of the deep foundation pit, the construction personnel are not allowed to live around the deep foundation pit, and at the same time, it is necessary to pay attention to the impact of the excavation of the deep foundation pit on the surrounding buildings, do a good job of reinforcement, and require technical personnel to observe at any time and make observation records.
3. Strengthen the safety inspection of construction lifting machinery, clean up the water around the foundation of construction lifting machinery and equipment in a timely manner, ensure the stability of the foundation, and improve the anti-storm and anti-collapse performance of construction lifting machinery and equipment.
4. Strengthen the temporary electricity safety inspection, especially the weatherproof measures in the distribution room, under special weather, the temporary electricity at the construction site must be cut off in addition to lighting, drainage and emergency electricity, and all power supplies must be cut off, after the disaster, all electrical facilities and lines can be put into use only after passing the safety inspection.
5. Strengthen the safety inspection of the formwork support system and scaffolding, whether the formwork support system is erected according to the special plan, and whether there is deformation and looseness; Whether the scaffolding meets the requirements of the specification, whether the scaffold body is deformed, especially whether the roof grape trellis wall pieces are fixed and deformed according to the requirements.
6. Strengthen the safety inspection of the basement or civil air defense project, whether there is water blown into the basement or civil air defense project, whether the preparation hole and underground passage are protected in place, and whether the support of the post-pouring belt is firm.
7. Strengthen the safety inspection of the construction enclosure, the retaining wall around the construction site and the building slope, and deal with the deformation observation of the construction enclosure, retaining wall and building slope in a timely manner.
8. Strengthen emergency duty and pay close attention to weather dynamics. After the end of the windy weather, the joint construction units should inspect all parts and links of the construction site, and can only start work after meeting the requirements.
How many levels of wind can a tower crane withstand?
Windy weather is common weather, many construction sites when encountering windy weather, still require the tower crane driver to continue construction, not only make the operator frightened, but also may cause serious tower crane accidents.
Due to the tight construction schedule, the construction site was also required to take risks as usual. When the wind blows, the tower crane driver who drives the tower crane will feel that the tower crane is shaking badly when operating the tower crane, and he is worried that there will be an accident. The tower crane operated by the tower crane driver is more than 20 meters high, only the balance arm forearm has 46 meters, because the building materials of the tower crane crane are several tons at every turn, the tower crane with poor balance itself is shaking very badly. A tower crane driver said: "I am very worried inside, and I am always afraid that the tower crane will fall." Due to the shortage of manpower, the construction site sometimes lets some workers who do not have a tower crane operation certificate operate the tower crane. Due to the inexperience of these people and the strong winds, accidents are more likely to occur.
According to the unified provisions of the tower crane tower base standard specification, when the wind exceeds level 4, the tower crane can work, but if the tower crane is in a non-working state, it should be parked downwind to ensure that the tower crane balance arm is not affected by the wind; When the wind force exceeds level 6, the tower crane should be stopped to avoid accidents in the balance arm.
Due to the long balance arm of the tower crane, the tower crane itself has been subjected to heavy building materials, and it is very dangerous to work forcibly against the wind, and the platform, walkway, skirting board and railing, ladder, handrail, and retainer are the channels and protective facilities for tower crane operators to walk on the tower crane. The quality of their installation is related to the personal safety of the operator, so it should be ensured that they are installed correctly and in good condition.
The counterweight is a trimming component to maintain the stability of the tower crane and realize the lifting performance of the tower crane.
Ballast is an important part to increase the stability torque of the tower crane and ensure the stability of the whole machine, and its quality and quantity are directly related to the stability of the tower crane.
Regulations on construction management under strong wind conditions:
1. In case of strong winds above level 6, open-air climbing and suspended high-altitude operations are not allowed.
2. During windy construction, the formwork should have temporary reinforcement measures against wind.
3. When there is windy weather of level 6 or above, the scaffolding erection and dismantling operations should be stopped, the outdoor formwork dismantling and installation of high-altitude operations should be suspended, and the open-air lifting and hoisting operations should be stopped, and the construction elevator must be stopped running, the ladder cage should be lowered to the bottom and the power supply should be cut off.
4. In case of level 5 and above strong winds, all formwork lifting operations should be stopped.
5. In case of windy weather, the tower crane disassembly and assembly operation should be stopped.
6. When the wind force is level 4 and above, the tower crane lifting operation shall not be carried out. When the wind force suddenly increases to level 4 during the operation, it must be stopped immediately, and the connecting bolts of the upper and lower towers should be tightened.
7. In case of strong winds of level 6 and above, it is strictly forbidden to install or disassemble the tower crane anchoring device.
8. In case of level 6 or above strong winds or gusts of wind during the operation, the tower crane operation should be stopped immediately, the rail clamp should be locked, the brake of the slewing mechanism should be completely loosened, and the crane arm could rotate with the wind.
9. In case of windy weather of level 6 and above, the operation of the piling machinery should be stopped, and when the wind force exceeds level 7, the pile driver should be parked downwind, and the cable wind rope should be added, or the pile should be put down on the ground.
10. After the strong wind weather of wind level 6 and above, the foundation pit and safety facilities should be inspected in time.
11. After the strong wind, the safety facilities for high-altitude work should be inspected one by one, and if loose, deformed, damaged and falling off are found, they should be repaired and improved immediately.
12. In case of six-level strong wind and heavy rain, scaffolding and other foundations should be inspected and accepted.
13. When the attached lifting scaffold encounters severe weather of level 5 and above, it shall not be lifted and dismantled; When resuming work after a strong wind of level 6 or above, it should be inspected and confirmed to be qualified before it can be used.
14. When the gondola construction encounters bad weather above level 5, the operation should be stopped, and the gondola platform should be parked on the ground, and the wire rope and cable should be tied and fixed.
15. In case of strong winds above level 5, the tool-type scaffold shall not be lifted or lowered.
16. The material hoist must stop running in bad weather with a wind speed of 13m/s and above.
Third, the key points of construction supervision and control in rainy days
(1) Make the following disclosure to the construction unit
1. Ensure the smooth flow of information. Supervise and improve the information management of construction enterprises, informatization is an important part of the scientific management of enterprises in the future, due to the uncertainty and suddenness of bad weather such as summer construction storms, it is difficult to predict the degree of damage, and it is necessary to strengthen the control and management of meteorological information, take effective safety measures in a timely manner, and strengthen prevention. 2. Comprehensive protection. The construction site involves a wide range, including the safety protection of various parts of the site and temporary facilities and the safety of all personnel, so when formulating safety measures, we must be comprehensive and meticulous, and we must not do anything because of small things, so as to leave hidden dangers and bring losses. 3. Scientific organization of construction. When compiling the construction organization design, fully consider the characteristics of the rainy period construction, arrange the project that is not suitable for construction in the rainy season in advance or postponement, reasonably arrange indoor and outdoor operations according to the weather, arrange indoor construction operations as far as possible in windy and rainy weather, do a good job of interspersing the process, improve work efficiency and construction speed, and stop construction in case of large stormy weather. 4. Rapid response to make emergency preparations for flood control, rescue and disaster relief, and during the construction during the rainy season, various protective measures should be further strengthened, and effective strengthening measures should be taken for scaffolding, material hoists, dual-purpose elevators, warehouses, protective sheds, temporary facilities, etc. Ensure that emergency and disaster relief materials and personnel are in place, and immediately activate the emergency plan in case of danger.
(2) Supervise and urge the construction unit to prepare for construction in the rainy season
1. Arrange work and rest time reasonably.
In summer, the construction time should be compressed to both ends as much as possible, avoid the high temperature at noon, and stop outdoor operations when the temperature exceeds 37 °C, and there should be ventilation and cooling measures when working indoors. In case of heavy stormy weather, all operations should be stopped and personnel should be evacuated to a safe place.
2. Do a good job of on-site drainage. (1) According to the construction plan and the general drainage plan, the natural terrain is used to determine the drainage direction, and the drainage ditch is dug according to the specified slope to ensure that the drainage is unimpeded. (2) In the rainy season, the construction site is close to the high ground, and the drainage ditch should be dug at the edge of the high ground to deal with dangerous rocks to prevent landslides, landslides and other disasters. (3) Ensure that the road is unimpeded, and the road surface is hardened or paved with gravel, slag or other materials according to the actual situation, and the arch is heightened as required. (4) Protection of raw materials, finished products and semi-finished products. The material library is comprehensively and regularly inspected, repaired in a timely manner, the surrounding drainage is good, the wall foundation is firm, no rain leakage, and corresponding rainproof measures are taken for the storage of steel and other materials to ensure the quality and safety of materials. (5) Set up continuous and smooth drainage facilities and emergency supplies in strict accordance with the requirements of flood control, such as water pumps and related equipment, plastic sheets, linoleum and other materials.
(C) for the supervision of key sub-projects
1. Masonry engineering:
The overall stability of the masonry is mostly taken from the adhesive such as mortar and the moisture content of the masonry material, both of which will be greatly affected during the construction during the rainy period. Therefore, during this period, the supervision agency adopts the methods of side station, inspection and parallel inspection to strengthen the inspection, and requires the construction unit to grasp the following key points:
(1) The construction in the rainy season should not use too wet masonry to avoid the loss of mortar, affecting the quality of masonry, bricks must be stacked in the rainy season, not watering. When building walls, it is required that dry and wet bricks are reasonably matched. When the humidity of the brick is high, it should not be put on the wall. The height of masonry should not exceed 1m; (2) In case of heavy rain, the work must be stopped, and the top of the wall must be covered with a layer of dry bricks to avoid heavy rain washing mortar. After heavy rain, the newly built wall washed by the rain should be turned over with the top two bricks; (3) For the window wall and independent brick column with poor stability, temporary support or ring beam should be poured in time to increase the stability of the wall; (4) The amount of masonry mortar should not be too much, and it should be able to meet the needs of masonry. The mixed mortar should pay attention to prevent the erosion of rainwater; (5) Continue the construction after the rain and review the verticality and elevation of the completed masonry; And check the masonry mortar joints, and take necessary remedial measures for places seriously washed by rainwater.
2. Concrete engineering:
(1) The formwork isolation layer should grasp the weather forecast in time before painting, so as to prevent the isolation layer from being washed away by rain; (2) In case of heavy rain, the pouring of concrete should be stopped, and the poured parts should be covered. (3) During the construction during the rainy period, the determination of the water content of the coarse and fine aggregate of the concrete should be strengthened, and the water consumption should be adjusted in time; (4) Before pouring large areas of concrete, it is necessary to understand the weather forecast for 2-3 days. Try to avoid heavy rain. A large number of rainproof materials should be prepared at the concrete pouring site to be covered in case of sudden rain during pouring; (5) The backfill should be tamped under the support of the formwork, and the backing plate should be added, and whether there is sinking should be checked in time after the rain; (6) When it rains, steel bar welding, butting and other work shall not be carried out, and rainproof work or construction should be done when it is urgently needed
3. Scaffolding:
The safety and stability of scaffolding directly affect the life safety of workers and the safety of buildings. During rainy construction, any carelessness and negligence can lead to accidents. Therefore, during the rainy period, scaffolding should take the following measures:
(1) Strengthen the scaffolding foundation. Many scaffolds are built directly on earth and stone foundations, and will sink when soaked in heavy rain during rainy periods, resulting in the scaffolding's support hanging or the scaffolding overturning. In order to prevent such accidents, steel plates can be added to the bottom of the scaffold or based on strip stones.
(2) Appropriately add connecting rods to the building. In this way, the integrity of the scaffold and the ability to resist overturning can be increased, and the stability can be increased;
(3) Anti-skid and anti-fall measures should be taken in places such as horse paths on scaffolding, such as replacing pedals with too smooth surfaces in a timely manner, and installing protective nets on both sides of the passage;
(4) Frequently inspect the connectors at the joints of the scaffolding, and strengthen and restore them in time if they are found to be loose or displaced;
(5) During the rainy period, it is not advisable to carry out too much construction on the scaffolding, the working surface can not be paved too large, and the number of personnel, components and other building materials on the scaffold should be controlled, and the action on the scaffold should not be too intense.
(6) Metal scaffolding should be protected from leakage. The junction of the scaffold and the on-site construction cable (line) should be well isolated from the insulating medium, and equipped with the necessary leakage protection device; Or rearrange the on-site construction cables (lines) to avoid handover with metal scaffolding.
Fourth, the rain and lightning protection of construction machinery and the electricity consumption of the construction site:
(1) Rainproof. All mechanical sheds should be erected firmly to prevent collapse and rain. Mechanical and electrical equipment to take rainproof, floodproof measures, can be set up rainproof shelter or sealed with rainproof cloth, mechanical installation site requirements are slightly higher, around the drainage is better. Install the grounding device. The leakage protection device of the mobile switch box should be reliable and sensitive;
(2) Protection against lightning strikes. Summer is the season of lightning, in order to prevent accidents caused by lightning attacks at the construction site, effective lightning protection devices must be installed in steel pipe scaffolding, tower cranes, freight elevators, etc., and the lightning grounding resistance shall not be greater than 10Ω.
(3) Anti-electric shock. The electricity consumption at the construction site must comply with the two-level protection of three-level power distribution, and the three-level electrical box is repeatedly grounded, and the resistance is less than 10Ω; Wires and cables should be reasonably buried, and there should be no aging or damaged cables; In case of stormy weather, professional electricians should be arranged to check on duty, and if necessary, the power supply of all equipment and tools must be disconnected before getting off work.
Source: Zhulong Supervision