There are a large number of bridge builders, and they live near the bridge site during the construction process. Generally, they take temporary buildings as their residence, which is not permanent, and the environment is harsh and the pollution treatment facilities are not perfect. Therefore, environmental pollution mainly includes: construction waste, domestic waste, food waste in kitchens and canteens, domestic water, feces and so on. The corresponding protection measures for the above aspects are: establishing fixed-point garbage disposal, storing domestic garbage and construction garbage separately, and clearing them regularly. Among them, anti-seepage garbage pool should be built for domestic garbage to avoid rainwater or residual moisture of domestic garbage from leaking and polluting underground water sources. For domestic water and canteen sewage, a simple oil drain tank and a secondary sedimentation tank should be built to discharge and treat the sewage centrally. Measures should be taken to prevent the spread and leakage of pollutants from food residues and toilet feces produced in canteens, and centralized collection and treatment should be carried out, and the principle of adapting measures to local conditions and using wastes should be adopted for timely treatment. At the same time, it is suggested to strengthen the training of construction personnel, strengthen the awareness of environmental protection, give priority to prevention, supplemented by treatment, control the environmental protection links in advance, and fundamentally grasp environmental protection to ensure that environmental protection can be implemented. Starting from the source, we should earnestly put people first, reduce the generation and spread of pollution sources, and thus prevent environmental pollution from expanding due to man-made reasons.
Two links of raw materials and auxiliary materials
There are many kinds of raw materials for bridge construction. In addition to the main materials such as sand, cement, gravel and steel bars, the auxiliary materials also include fillers, health-care materials, sealing materials and release agents. In bridge construction, when the construction strength of high-strength concrete is higher than C30 concrete, the requirements for raw materials are strict, and the sand and gravel must be screened and washed before they can be used. In this way, a lot of water is needed for washing materials, and the used water must be treated to meet the standard before it can be discharged. Waterproof, rainproof, centralized drainage and centralized treatment measures should be taken for the washing material site. Water for sand washing and gravel washing should be discharged centrally, and secondary or tertiary sedimentation tanks should be built, and reclaimed water reuse facilities should be built to avoid waste of water resources. In terms of auxiliary materials, environmental protection materials that are economical and reliable and technically feasible are preferred, so that waste packaging and surplus materials can be properly recovered in time before and after use. For release agents and other materials, relevant tests should be done, and environmentally friendly products that are nontoxic, harmless and pollution-free should be given priority. Strictly controlling the entry of all kinds of raw and auxiliary materials is the fundamental move to do a good job in environmental protection. Do a good job of storing raw materials. Storage sites such as sand, gravel and cement should be hardened, drained and rain-proof, and sites prone to dust sources should be covered for seasonal windy weather.
3 construction technology links
Due to the complexity of bridge construction technology, only a few key links that are easy to cause environmental pollution are listed. In pile foundation construction, if bored piles are used, a large amount of mud will be produced, which is necessary for the project, but a large amount of mud will cause certain pollution to the environment, and it takes about 50 t of mud to produce only one pile foundation. The slurry is also mixed with auxiliary pulping additives, such as cellulose and sodium carbonate (commonly known as soda ash). If it is not handled properly, it will pollute the water source and alkalize the soil, and the pH value of the mud can reach more than l0, so it is particularly important to properly handle the mud. For mud, a secondary sedimentation tank should be set for recycling, and the used mud should be pumped out to dry. Mud pond treatment is to add acidic chemicals, reduce the pH value of mud, cover the soil and restore the surface. Because most of the bridge concrete curing water uses oily release agent, a lot of water should be used to wash and dilute the release agent during curing. Therefore, the solidified water must be recycled after simple treatment, and a grease trap should be established to separate the diluted oil mixture to ensure no pollution to surface water and groundwater. The grease trap should be cleaned regularly. The materials used to fill the gaps in the formwork are mostly rubber and foam, which should be cleaned in time after use, and the rubber should be collected in a unified way to avoid white pollution and the death of foam after being eaten by poultry and livestock. The film plastic sheeting used for concrete curing should also be cleaned regularly and properly handled to prevent secondary pollution. For steel bar welding, especially when double-sided arc welding is used, attention should be paid to collecting and recycling the remaining covered electrode head to prevent the flux carried on the covered electrode from polluting surface water and groundwater. When flash butt welding and arc welding are used, attention should be paid to setting up a dazzling shed to prevent light pollution.
4. Long construction period
Because the bridge technology is complex, the construction period is generally long, which takes one to several years, so my temporary occupation time is longer, and the temporary occupation area of precast beam slab, storage beam slab and erection bracket is also larger, so my temporary occupation time is longer, which affects the biological environment. Especially in the construction of pile foundation, pile cap, column and capping beam, it is necessary to cofferdam the river, change the flow pattern and section, and cause man-made environmental damage to the upstream and downstream. It is suggested that the structural concrete in construction water should be calculated as much as possible to avoid the upstream and downstream local coastal areas being washed away due to excessive blocking time and area. At the same time, prepare for flood discharge during flood control period. For rivers with migratory organisms and fish, it is necessary to do a good job in migration channels to ensure that the ecological environment is not out of touch. After the construction is completed, the cofferdam shall be dismantled in time to restore the original appearance and avoid causing
Secondary pollution. For temporary occupation, the site shall be cleaned after occupation, and the waste shall be moved to the designated place in time. Recover after improving the soil. During the bridge construction, the original river bank should be temporarily strengthened and the river channel should be dredged. If there is any damage, the damaged area must be restored to ensure the normal operation of the river and reduce environmental hazards.
5 frequent use of machinery in the construction process
Pay attention to bridge construction machinery, including drilling (digging) piles, generators, air compressors, cranes, vibration machinery and their noise and vibration effects.
Light pollution and tail gas emissions are also very serious. Among them, the people affected by noise are mainly site workers and nearby residents, and the vibration is affected by nearby structures. Exhaust emission and light pollution mainly affect the surrounding environment. Therefore, the pile drilling machine should use hydraulic machinery as much as possible, and the construction machinery should use clean electric energy as much as possible. For construction machinery that really needs to discharge tail gas, it is necessary to install a tail gas purification device. High noise construction should be avoided as far as possible at night, and sound insulation screens should be added when necessary. For the machinery polluted by strong light used in the construction site, long-term use should be avoided and the construction period should be arranged reasonably. For vibration, isolation measures such as damping ditch should be set up.
6 site cleaning and reclamation after construction.
After the completion of bridge construction, the demolition of cofferdam and the hardened construction site and road during construction have no use value. Embankments and dams should also be resumed and postponed, and rivers should be dredged. Therefore, environmental pollution can not be ignored. Firstly, the site is reclaimed, and the hardened sites and roads in the construction process are cleared of construction waste and pedestal concrete first, and then the soil is loosened, and the humus topsoil is evenly distributed with a thickness of more than 30 cm. When dredging rivers, attention should be paid to avoid causing new sediment pollution downstream or leaving permanent construction waste that destroys natural water bodies. Both sides of the river embankment should be restored according to the requirements of water conservancy and environmental protection. After the site is cleared and reclaimed, the inspection of reclamation should be strengthened to ensure that no new pollution sources are formed. The above aspects are only the author's suggestions. The key is to deepen the awareness of environmental protection at the grassroots level, put people first and give priority to prevention, so that everyone's awareness of environmental protection can be enhanced, environmental protection measures can be put in place and play a corresponding role. Only in this way can we help solve the centralized environmental pollution, minimize the harm of environmental pollution, and realize the environmental protection construction during the highway bridge period.