What are the main points of rainy season construction?
A, the rain period construction requirements and preparation work
1, the requirements of the rain period construction. According to the characteristics of rain period construction, the construction organization design is compiled. Reasonable construction arrangement; Pay close attention to the weather forecast and prepare for flood control.
2, the rain period construction preparation. Do a good job of site drainage; Do a good job of rain protection for raw materials, finished products and semi-finished products; Formulate drainage and rainproof measures for on-site houses and equipment; Drainage requires enough pumps and related equipment, and suitable waterproof materials such as plastic sheets and linoleum are prepared.
Second, the rain period construction measures
Construction in rainy season mainly solves the problem of rainwater drainage. For the construction site of large and medium-sized projects, the overall planning of temporary drainage system must be done, including preventing off-site water from flowing into the site and discharging off-site water. Its principle is to intercept water upstream and divide water downstream; Pit bottom pumping and ground drainage. Planning and design should be based on the maximum rainfall and rainfall period over the years, combined with local topography and construction requirements.
Generally, temporary drainage ditches are set around buildings to prevent off-site water from entering the venue. The drainage in the construction site is relatively simple: as long as the corresponding flow rate is determined, the matching water pump and artificial drainage can be selected; The construction site above the ground can be used as long as the corresponding drainage channel does not make the site accumulate water.
In addition, the impact of rain on the construction of sub-projects is various. For some outdoor sub-projects that are greatly affected by rain, corresponding measures should also be taken to make the project go smoothly.
1, earthwork and foundation engineering
Earthwork and foundation engineering are greatly affected by rain, so the following points should be paid attention to: (1) When excavating foundation trench (pit) and trench pipe in rain period, attention should be paid to slope stability; In order to prevent being washed down by rain, steel wire mesh can be nailed on the slope and coated with 10 cm fine stone concrete; Plastic sheets can also be used to cover slopes; The working face in rainy season should not be too large, and should be completed by stages. After the foundation is dug to the elevation, it shall be timely accepted and concrete cushion shall be poured. If the foundation is soaked by rain, necessary excavation and backfilling should be carried out to restore the bearing capacity of the foundation pit; In order to prevent the foundation pit from flooding, the drainage ditch and collecting well should be made in the pit, and the necessary drainage force should be organized during excavation; Pools and basements located underground should be carefully built. Earthwork backfilled before rain should be rolled in time, and its surface should form a certain slope, so that the rain can be discharged automatically; When the rainfall is heavy, large-scale earthwork construction should be stopped; Measures should be taken to prevent rainwater from washing around the earthwork piled up on the construction site.
After the foundation construction is completed, we should pay close attention to the backfill work around the foundation pit. After artificial precipitation (drainage) stops, the buoyancy of box foundation anti-floating stability and foundation shall be checked and accepted. The anti-floating stability coefficient should not be less than 1.2 to prevent the foundation from floating or tilting. If the anti-floating stability coefficient cannot meet the requirements, pumping shall be continued until the upper load of construction meets the anti-floating stability requirements. In case of rainstorm, if the water pump cannot effectively reduce the height of accumulated water in time, the accumulated water should be poured into the box foundation in time to increase the anti-floating ability of the foundation.
2, masonry engineering
The overall stability of masonry depends on the binder of mortar and the water content of masonry materials. The following points should be grasped: bricks must be piled up in a centralized way during the rain period, and it is not suitable for watering. When building a wall, you need a reasonable mix of dry and wet bricks. Don't go up the wall when the bricks are wet. Masonry height shall not exceed1m; In case of heavy rain in rainy season, work must stop. After bricklaying, a layer of dry brick should be spread on the top cover of brick wall to avoid heavy rain washing mortar. After the heavy rain, the newly built wall washed by rain should be turned over to build the top two layers of bricks; For the wall between the window with poor stability and the independent brick column, temporary support or ring beam should be set up in time; During masonry construction, the internal and external walls should be built at the same time as far as possible, and the corner should be connected with the T-wall at the same time. In case of typhoon, temporary support should be added in the direction opposite to the wind direction; The dosage of masonry mortar should not be too much, so as to meet the needs of masonry. Pay attention to prevent the rain from washing away the mixed mortar; When the construction continues after the rain, the verticality and elevation of the completed masonry should be rechecked, and the mortar joint of the masonry should be checked. If the rain is washed seriously, necessary remedial measures should be taken.
3, concrete engineering
The weather forecast should be grasped in time before the template isolation layer is painted to prevent the isolation layer from being washed away by rain; Stop pouring concrete in case of heavy rain, and cover the poured part. Cast-in-place concrete should consider the position of several construction joints according to the structural situation and possible; During construction in rainy season, the determination of water content of coarse and fine concrete materials should be strengthened and the water consumption should be adjusted in time; Before large-scale concrete pouring, it is necessary to know the weather forecast for 2-3 days and try to avoid heavy rain. A large number of rain-proof materials should be prepared at the concrete pouring site so as to be suddenly covered by rain when pouring; Backfill soil supported by formwork should be compacted and padded, and check whether there is subsidence in time after rain; When it rains, steel bars shall not be welded or butted. When in urgent need, rainproof measures should be taken or the construction site should be moved indoors. Newly welded steel bar joints should be protected from rain, so as to avoid brittle fracture of joints during quenching and affect building quality.
4, lifting engineering
Component stacking area should be flat and solid, with good drainage around. It is forbidden to accumulate water and soak in the component stacking area to prevent the soil from sticking to the embedded parts. Tower crane foundation must be higher than the natural ground 15cm. It is forbidden to soak the foundation with rain. When hoisting after the rain, the stability of the tower crane itself should be checked first, and then the trial hoisting should be carried out under the condition that the tower crane itself is safe from rain damage, and the component should be hoisted to about 1 m, and then the hoisting work should be carried out after it has been stabilized for many times. Rainy days may affect the driver's sight. If the driver has no experience in lifting in rainy days, it is best to stop lifting. Or ask an experienced driver to do it; When the construction is stopped, the hook of the tower crane should be retracted close to the tower body, and no objects such as slings and building components should be left on the hook; In rainy days, the friction coefficient between the rope and the component decreases because the surface of the component and the hanging rope are wet, which may lead to serious quality and safety accidents such as component slipping. If necessary, measures such as increasing the surface roughness of ropes and components can be taken. When hoisting in rainy days, the forbidden area on the ground should be expanded, and additional personnel should be sent to guard when necessary.
5, roofing engineering
The coiled material waterproof roof shall be constructed before the rainy season as far as possible, and roof downpipes shall be installed at the same time; It is forbidden to construct linoleum roof in rainy days, and linoleum and thermal insulation materials shall not get wet by water; Wet paving construction technology should be adopted for roof construction in rainy season. Wet paving method is to spread the coil on the wet base, and spray 1-2 cold priming oil first. Spraying should be carried out at the initial stage of cement mortar solidification to prevent the base from being soaked. If the base is flooded, linoleum can only be laid after the surface of the base is dry.
6, plastering engineering
Outdoor plastering is not allowed in rainy days, and the weather change in 1-2 days should be predicted at least. For the wall that has been constructed, attention should be paid to prevent rainwater pollution; Indoor plastering should be carried out after leveling as far as possible, at least the leveling layer has been finished and a layer of linoleum has been laid; Rainy days are not suitable for painting top coat.
7. Scaffolding
During construction in rainy season, scaffolding should take the following measures: reinforce scaffolding foundation. The bottom of the scaffold is padded with steel plates or based on strip stones; Appropriately increase the connecting rod with the building. Anti-skid and anti-falling measures should be taken where people pass, such as the "path" on scaffolding; Check the fittings at the scaffold joint, and reinforce and repair them immediately if they are loose or displaced; In the rain period, too much construction shall not be carried out on scaffolding, and the working face shall not be paved too much. Controlling the number of people, components and other building materials on scaffolding should not be too intense; Anti-leakage measures should be taken for metal scaffolding. The joint between scaffold and site construction cable should be isolated with insulating medium and equipped with necessary leakage protection device; Or rearrange the construction cables to avoid handover with metal scaffolding.
8. Rainproof and lightning protection of construction machinery and electricity consumption at the construction site
All mechanical operation sheds shall be firmly erected to prevent collapse and leakage. Rainproof and flood control measures should be taken for electromechanical equipment, and the grounding safety device and the leakage protection device of the motor switch box should be reliable; In rainy days, prevent accidents caused by lightning, tower cranes, people and goods elevators, steel pipe scaffolding, etc. Lightning protection devices must be installed if the construction site is higher than the building; Exhaust holes of construction machinery shall be blocked with plastic sheets or other waterproof materials; It is best to move the machinery in the pit to the ground to prevent the rain from being flooded; On-site construction cables should be arranged in a centralized way to prevent disorder, and cables with aging or damaged insulation sheath should be replaced in time; Unnecessary cables should be recycled in time.
Third, the rain period construction safety measures
Rain-proof, wind-proof, lightning-proof, electricity-proof, flood-proof and other work should be done well in the rain period construction. Drainage ditch, foundation pit, pit, etc. It should be set in foundation engineering, fences and warning signs should be set for water accumulated after rain, and pits and wells with foundation pit exceeding 1 m should be supported; All machinery and equipment should be located in a high-lying, moisture-proof and rain-proof place, and a fortified canopy should be set up. The power supply line of mechanical equipment should be well insulated, with perfect protection and zero connection; Scaffolding should be inspected frequently, and problems found should be handled in time or replaced and reinforced; High-rise buildings, scaffolding and structures should be equipped with temporary lightning protection devices according to the regulations of electrical specialty; Anti-skid measures should be taken for scaffolding on the road, and it should be cleaned in time after rain, and the safety measures of scaffolding and electrical equipment should be checked at any time; Bare wires are strictly prohibited on site, and special personnel are appointed to maintain and manage power facilities. It is strictly forbidden to change and dismantle the lines without permission, and strictly control various rules and regulations. All construction workers are forbidden to wear slippers and hard and slippery shoes.
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