This project is limited by the construction period, the construction needs to go through two winter seasons and a rainy season, specific construction arrangements under special climatic conditions are as follows:
1 winter construction arrangement
This contract section of the project period of 14 months, the entire project after two winters. In the winter construction must be done in advance to prepare for the construction, and take reliable technical guarantee measures, the main contents are as follows:
1.1 Construction Preparation
1) do a good job of winter program and construction organization plan;
2) the facilities and materials in advance to take the snow, anti-freezing and other measures;
3 on the cold pulling of reinforcing steel and tension should be specially formulated Construction process requirements and safety measures;
(4) in advance of the trial matching winter construction concrete ratio;
(5) the development of winter construction of fire prevention, anti-freezing, gas poisoning and other safety measures;
(6) on the staff, civilian workers in advance of the winter construction of the technical briefing.
1.2 Construction Methods and Technical Measures
1.2.1 Winter Construction of Steel Reinforcement and Prestressing
(1) Welding of steel reinforcement shall be carried out indoors as far as possible. When the wind is more than grade 4, wind-blocking measures should be taken. When the ambient temperature is lower than -20℃, the welding can not guarantee the quality, stop welding operations.
(2) the cold drawing equipment for steel bars, pre-stressing tensioning equipment, and instrumentation work oil, should be selected according to the actual use of the ambient temperature, and should be used under the conditions of the ambient temperature for supporting calibration.
3) The hole pressurization of prestressing concrete shall be carried out under normal temperature.
1.2.2 Winter construction of concrete
(1) Technical requirements for concrete preparation and mixing
①Silicate cement and ordinary silicate cement should be preferred, and the water-cement ratio should not be greater than 0.5.
②Winter concrete ratio design should be based on the strength of the concrete pouring, transportation mode, etc. to make comprehensive consideration. Admixture of additives must be carried out in accordance with the specifications.
③The temperature of each material for mixing concrete should meet the temperature required after mixing and synthesizing the concrete mixture (the temperature of the concrete mixture out of the machine should not be lower than 10℃, and the temperature into the mold should not be lower than 5℃). Consider heating the mixing water first, and then consider heating the aggregate when it still cannot meet the needs. Cement can only be kept warm, not heated. Each material needs to be heated temperature should be calculated according to the specification of the "winter construction thermal formula" to determine, but shall not exceed the specification of the maximum temperature.
④To ensure the ease of concrete, fluidity, can extend the mixing time, generally 50% longer than room temperature.
(2) Technical requirements for concrete transportation and pouring
①The transportation time of concrete should be shortened as much as possible, and the containers for transporting concrete should take appropriate heat preservation measures. The concrete conveying pump pipe should be wrapped with heat preservation.
②The concrete should be cleared of ice, snow and dirt on the template and reinforcement before pouring.
3 ③ winter construction joints concrete, in the new concrete before pouring should be heated so that the joint surface has more than 5 ℃ temperature, after the completion of the pouring, measures should be taken to make the concrete joint surface continue to maintain a positive temperature, until the newly poured concrete to obtain the required frost strength.
1.2.3 Technical requirements for concrete maintenance
The maintenance method of concrete shall be calculated according to the technical and economic comparison and the specification of "Thermal Calculation Formula for Winter Construction". Maintenance method should be based on the site temperature, surface factor of the structure and other factors, can choose the heat storage method, steam heating method, heating method or electric heating method, in order to ensure that the concrete structure is not subject to frost damage. This project is proposed to use the following methods for winter concrete maintenance work:
①The exposed surface of concrete is covered with adhesive tape and straw bags, and watering is not allowed in negative temperature.
②The temperature at the beginning of the concrete maintenance, shall not be lower than the temperature specified in the antifreeze, when the temperature does not reach the specified temperature, and the concrete strength is less than 3.5Mpa should be taken to keep warm, so that the temperature of the concrete is not lower than the temperature specified in the antifreeze.
1.2.4 Demolding of concrete
(1) shall meet the requirement of demolding strength under normal temperature of concrete, and at the same time, meet the requirement of anti-freezing:
The side mold shall be demolded only when the strength of concrete reaches over 2.5Mpa and its surface and corners are not damaged due to demolding. The bottom mold shall be dismantled only when the concrete strength reaches 100% of the designed strength of the concrete.
(2) The temperature difference between the concrete and the environment shall not be more than 15℃, when the temperature difference is above 10℃ but below 15℃, take covering measures on the surface of the concrete immediately after dismantling the formwork, such as covering the straw bag and colorful adhesive tape.
1.2.5 Winter construction of drilled pile
(1) The winter construction of drilled pile concrete is mainly to ensure that the concrete is not frozen during filling and can be filled smoothly.
(2) When the pile head is exposed to the water (or ground) or not exposed to the water (or ground) but within the freezing range, the pile head concrete should be covered with heat preservation and maintenance.
(3) The temperature of the concrete mix is required to be not less than 5℃ during filling; no antifreeze or antifreeze is allowed to be mixed in the concrete.
1.2.6 Quality inspection
In accordance with the specification requirements of the winter construction quality inspection methods for winter construction of all projects to carry out a strict inspection, to eliminate hidden problems of engineering quality. In addition to the following requirements:
(1) During the period of concrete mixing and filling, measure the temperature of water and coarse and fine aggregate when loading into the mixer, the mixing temperature of concrete, the filling temperature and the ambient temperature. Test at least 4 times per work shift. When low-temperature early-strength concrete is used or when heat storage is used to maintain the concrete, the test is conducted at any time within 3 days after filling.
(2) winter construction concrete in addition to the standard maintenance specimens made in accordance with the provisions of the specimen, but also according to the needs of the building maintenance, demolding and load bearing, the production of construction inspection specimens, in order to find out the strength of the development of the situation. Construction check specimen maintenance should be the same as the building.
1.3 Mechanical equipment winter cold, frost, fire, anti-skid measures
1) before entering the winter on all mechanical equipment to do a comprehensive repair and maintenance, good oil and water management work, combined with the seasonal maintenance of machinery and equipment, and timely replacement of lubricating oil of the appropriate brand; use of antifreeze to ensure that mechanical equipment to ensure that antifreeze meets the requirements of the local antifreeze; do not use antifreeze to take appropriate anti-freeze mechanical equipment to take appropriate anti-freeze measures. Mechanical equipment to take appropriate antifreeze measures (to take downtime after the discharge of cooling water or into the warming workshop)
(2) a variety of vehicles using fuel, according to the ambient temperature selection of the appropriate type, cold start, to run at low speed for a distance and then gradually increase the speed of the car.
(3) winter vehicles before starting the engine, it is strictly prohibited to use an open flame on the existing fuel system for sludge heat, in order to prevent fire.
(4) ice and snow day driving, the car should be set up anti-skid chain; driver in the car before checking to make sure that the vehicle's braking device to achieve a good state, do not meet the requirements shall not be out of the car, in the event of more than six winds, snow and fog bad weather to stop running.
(5) the strict implementation of the system of fixed machine and fixed person, machinery custodian should stick to their posts, watch over the equipment, and make the appropriate records.
1.4 Other precautions for winter construction
(1) When working at height, do a good job of anti-slip measures for the steel structure and take reliable windproof measures.
(2) When steel structure welding is carried out in winter construction, corresponding welding process should be adopted to ensure welding quality.
(3) Strengthen the warming and maintenance of mechanical equipment during winter construction to ensure that the equipment can operate normally.
(4) in the wind, snow, fog days should stop construction.
(5) winter construction pay attention to winter "five preventive" work implementation.
2 rainy season construction arrangements
This contract section of the construction period of 14 months, the entire project after a rainy season, the impact on the construction of the project is greater, so we must make good preparations for the construction in advance, and to take reliable technical assurance measures. The main contents are as follows:
2.1 Construction preparation work
1) make the rainy season program and construction organization plan;
2) formulate the rainy season construction of the water, overhead work and other safety measures;
3) prepare the rainy season construction of the flood prevention materials, machinery and equipment, and the necessary facilities for the rain cover.
(4) keep in touch with the local meteorological department frequently, obtain meteorological information at any time, grasp the rainfall trend of the year, month and day, arrange the construction reasonably, and try to avoid the construction during the bad weather.
5(5) to the staff, civil workers in advance of the rainy season construction of technical briefing.
2.2 Construction Methods and Technical Measures
(1) A leading group for flood control is set up in the project department, with the project manager as the leader. Each section will set up a flood control team, headed by the section manager, and will be subject to the unified scheduling of the flood control team. The project department flood prevention news team obey the local government and Zhenlian road command unified dispatch.
(2) Project materials, especially cement and steel bars, should take measures to prevent water and moisture. Bulk cement using cement tanks, bagged cement and additives, etc. in the brick structure of the cement warehouse, warehouse floor for the concrete structure, and higher than the outdoor ground at least 20cm. outdoor bagged cement, additives, etc. to be used as soon as possible, often time not used to transfer to the warehouse stacking.
(3) the template, rebar, etc. and the ground with sleepers to isolate, when it rains with rain tarpaulin cover. The silt and debris on the template and reinforcement after rain should be removed before pouring concrete.
(4) check the water content of sand and gravel in time to adjust the ratio before concrete pouring, and set up a canopy in case of rain when pouring to prevent the rain from washing away the concrete.
(5) During the rainy season, the pit excavation should be equipped with water retaining ridge to prevent the inflow of ground water. The pit is equipped with a water collection well, with enough pumping machines, and the ramp is equipped with water catchment measures. After the pit is dug, concrete or bedding should be poured in time to prevent being soaked by water.
(6) Strengthen the observation of subsidence in poor foundation areas.
(7) Lightning protection measures should be set up in the minefield, and the towering structure should have lightning protection design. Coastal areas should consider typhoon protection measures.
(8) Non-motorized construction machinery and equipment should be padded in the rainy season to prevent moisture. Electrical equipment used in the open air should have reliable anti-leakage measures (such as adding leakage protector, etc.).
9 during the rainy season construction, to strengthen the site inside and outside the drainage system inspection, dredging or reinforcement, if necessary, increase drainage measures.
3 Typhoon and Flood Control Arrangements
3.1 Construction Preparation
(1) Implementation of the organization: the establishment of a leading group of typhoon and flood control, led by the manager to deal with typhoon and flood control matters.
(2) the establishment of rescue team: in the period of typhoon and flood control, to participate in the rescue of national property and people's production safety, reduce losses.
(3) Arrangement of duty: typhoon and flood season to arrange for duty, pay attention to listening to weather forecasts, to grasp the typhoon and tidal flood trends.
(4) Prepare the typhoon and flood control materials, and make plans for typhoon and flood control, so as to be prepared.
(5) Education on typhoon and flood control: Strengthen education to improve the awareness and participation of all workers in typhoon and flood control.
(6) Transportation and Medical Assurance: During the period of typhoon and flood control, there must be a duty car to transport personnel and materials, and medical personnel present and ready to rescue the injured.
3.2 engineering structure of typhoon and flood control measures
(1) typhoon period should be ready for emergency rescue work, the ship and the various high-altitude workers wear life jackets.
(2) before the arrival of big waves, according to the wind and wave forecast in the pier long and high propulsion surface and beam head for temporary protection.
(3) When the sea conditions are good, the construction of low-water working surface should be accelerated to ensure the smooth progress of the overall construction.
3.3 Measures for ship and machine equipment against Taiwan and flood
(1) Implement anchorage for each operating ship to avoid wind.
(2) Implement the duty and action plan of each ship for typhoon prevention.
(3) from the wind and typhoon basic point of consideration, in the construction of this project, special arrangements for a 1228kw large tugboat, focusing on both the construction of typhoon protection against sudden winds, each construction vessel are equipped with typhoon anchors. If the ship encounters a sudden wind during construction, if it cannot be towed to a sheltered harbor in time, it will immediately anchor at the site or tie up to a floating drum.
(4) No machinery and equipment shall be parked at the dockside during the typhoon prevention period.
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