From primary school, junior high school, high school to university and even work, everyone will inevitably contact or use papers. Thesis is a comprehensive style, through which we can directly see a person's comprehensive ability and professional foundation. So how to write a good paper? The following is my paper on river dredging construction, which is for reference only and I hope it will help you.
River dredging construction paper 1 The river has many functions such as tourism, navigation, drainage and flood control. The smoothness of the river directly affects the flood discharge and flood control functions of the river, especially in the flood season every year, which requires higher smoothness of the river. However, due to the influence of the river itself, buildings on both sides of the river and bridge erection, it is very difficult to dredge the river. Therefore, in order to ensure the smooth flow of morality and the safety of life and property of nearby residents, the river dredging project should be done well and must not be sloppy.
First, the significance of river dredging project
Doing a good job in river dredging is an important work to ensure flood control safety, regional construction and regional economic development. However, in many areas, there are the following problems in river dredging: the cross-hook beach surface near the toe of the river bank is very low, and a large amount of water will accumulate at the toe of the river bank during flooding, which seriously threatens the safety of the river bank, especially in areas with loose soil, which not only threatens the safety of the river bank, but also threatens the regional safety; Some sand embankments have some sand foundations. If the water flow is too large or the water level is too high, it will lead to the danger of bank collapse and seriously threaten the safety of the bank. Excessive sediment deposition will raise the river bed, affect the flood discharge capacity of the river and reduce the flood control standard of the river; The lack of river management leads to many dangerous sections in the river. Due to the above problems in river engineering, once the river is seriously silted, the flood discharge is not smooth or even impassable, it will lead to the direct impact of floods on the river banks and seriously threaten the lives and property safety of local residents. It can be seen that the dredging project can effectively reduce the river sediment, improve the flood discharge capacity of the river, stabilize the river, eliminate dangerous situations, ensure the safety of local residents' lives and property, and promote the sustainable development of local construction and economy.
Second, the river dredging engineering construction technology analysis
(1) Preparatory work
The preliminary work of river dredging project mainly includes the following aspects:
1, construction planning
Before the construction of river dredging project, construction planning should be done well. Construction planning should be based on the specific situation of the river, strictly in accordance with the relevant regulations and requirements, and reasonably arrange the construction intensity, construction period and land use scope. At the same time, scientifically arrange civilized construction work such as safety, sanitation and fire prevention to prevent the dredging construction from bringing unnecessary troubles to the lives of local residents.
2, lofting and measurement work
The accuracy of construction survey directly affects the safety and accuracy of dredging construction. Therefore, in the preparatory work, supervisors and designers should do a good job in measuring mileage piles, engineering coordinates and other related work, and at the same time do a good job in measuring disclosure before construction.
3, mechanical equipment preparation
The river dredging project is gradually developing towards mechanization, and the construction machinery plays a vital role in the river dredging project, even the dredging work cannot be carried out. Therefore, in order to ensure the smooth and orderly construction of river dredging project, it is necessary to prepare suitable mechanical equipment according to the actual situation of river dredging project before construction, so as to ensure the maintainability, flexibility and applicability of the equipment, thus ensuring the stable and efficient construction of river dredging project.
(2) Analysis of common construction techniques in river dredging engineering.
The construction technology of river dredging project should be adapted to local conditions, and the appropriate dredging construction technology should be selected after comprehensive analysis according to the local actual situation. At present, the construction techniques commonly used in river dredging projects mainly include the following aspects.
1, grab, transport and pump dredging construction technology
For rivers where small ships can pass smoothly, the construction scheme of dredging and pumping is usually adopted, and grab dredgers are used to excavate silt. Earthwork excavated by grab dredgers can be directly parked on the self-propelled mud barge, and after the self-propelled mud barge is fully loaded, it will be transported to the designated mud dump by the mud suction ship that travels to the river. The advantage of this dredging construction technology is that it is relatively less affected by the transportation distance and is not limited by the location of the mud dump. At the same time, its disadvantage is that excavation and transportation equipment will affect each other during construction, and the construction is relatively inflexible.
2. Construction technology of small cutter suction dredger
This dredging construction technology is usually suitable for rivers that small ships can pass through. This dredging construction technology uses a small cutter suction dredger to excavate silt, and uses a closed pipeline for earthwork transportation. The advantage of this dredging construction technology is that it can realize the integrated construction of excavation, transportation and suction, which not only has very high construction efficiency, but also has very good construction quality. At the same time, the deployment of this dredging construction technology is not flexible, and it is affected by factors such as bridge and river width.
3, mud pump construction technology
The construction technology of mud pump is usually suitable for rivers with a width of about 5 ~ 10m. The section of this river is relatively narrow, and there is a lot of domestic garbage in the river, which is not convenient for other large and medium-sized equipment to drive. In view of this situation, mud pump construction technology is usually adopted. In the concrete construction process, temporary cofferdams should be built at both ends of the river, and then the water in the river will be discharged. The garbage in the river is cleaned manually before mud is used. The advantage of this dredging construction technology is that it can realize the integrated construction of excavation, transportation and suction, and the construction efficiency is very high. At the same time, the disadvantage is that it is greatly affected by the row spacing, and obstacles such as domestic garbage in the river will affect the production efficiency of the mud pump.
4, wet soil ashore construction technology
The construction technology of wet soil ashore is to excavate a small ditch with a depth of 1.5m and a bottom width of about 1m at a distance of 3m from the dike exit line. During construction, according to the specific conditions of river course design, small excavators are used for excavation, and the excavated earthwork and silt can be used as river bank protection. In the process of excavation construction, layered excavation should be adopted, and the embankment filling construction should follow the following principles: layered loading and uniform lifting. At the same time, this dredging construction technology can effectively solve the problem of inconvenient driving of river dredging equipment in the river, and has a very good effect in practical application.
(3) Sludge treatment
If effective measures cannot be taken to properly treat the sludge cleared from the river, it will cause secondary pollution to the environment, especially many sludge contains many harmful pollutants. If piled up in the natural environment at will, long-term attempts will lead to the volatilization of harmful substances or the infiltration of rainwater into the soil, which will affect the domestic water consumption of residents, threaten people's life and health, and also threaten the normal growth of crops. The silt in the river is removed by dredgers and transported to the designated place for treatment. The following two methods are usually adopted for the sludge cleared from river courses: on the one hand, the seriously polluted river course sludge, after drying, is unified with the industrial waste residue and sludge used for brick making, and then burned centrally, and the sludge rich in organic matter can be used as fertilizer after fermentation treatment; On the other hand, for the unpolluted river silt, it can be directly stacked in the designated position, and can be used as road paving and farmland soil supplement after natural air drying.
In a word, as an important water conservancy project, river plays a vital role in national economic development, regional construction, flood control and drainage. Strengthening river dredging is of great significance to improve the flood discharge, flood control and irrigation and drainage capacity of rivers. Because there are some differences in environmental conditions, geological conditions and surrounding buildings in different rivers, in order to improve the efficiency of dredging, we should do a good job in preliminary preparation according to the specific conditions of rivers, adopt appropriate dredging construction technology according to local conditions, and do a good job in sludge treatment to prevent secondary pollution to the environment.
River Dredging Construction Paper 2 1 Present Situation of Small and Medium-sized Rivers in Cities
Rivers in China are widely distributed and numerous. There are more than 50,000 small and medium-sized rivers, and the basin area exceeds1100,000 m2[ 1]. Small and medium-sized rivers in cities are responsible for flood control and drainage, landscape tourism, ecological balance and other functions, and are an important part of urban construction. However, with the acceleration of urbanization, the rapid development of urban economy and population, the pollution and siltation of small and medium-sized rivers in cities are also increasing, and the water quality is declining, mainly as follows:
(1) Many small and medium-sized rivers have accepted urban sewage for a long time, and the urban rivers are seriously silted, and the river bottom is high or even blocked in some areas, and the sediment pollution is serious, and the river ecosystem is destroyed, which is not conducive to the self-repair of water bodies;
(2) Due to the upstream interception of small and medium-sized rivers in cities, the water supply source is relatively scarce, the passenger flow is small, and the dilution ability is poor. Coupled with poor water flow, exchange capacity and self-purification capacity are reduced, resulting in a large number of pollutants deposition and sludge formation. The pollutants in the sludge are deposited at the bottom of the river bed for a long time and released again, resulting in endogenous pollution. At the same time, river siltation will also reduce the flood discharge capacity of the river and increase the disaster risk. Once in the flood season, it is very likely to cause rainwater overflow and even flood [2]. Therefore, it is urgent to dredge small and medium-sized rivers in cities.
2 Dredging technology analysis
The dredging method of small and medium-sized rivers in cities is different from that of large rivers and port waterways, and it has the characteristics of narrow rivers, shallow rivers, small single-section dredging workload, many buildings on both sides of the river, difficult passage of large mechanical ships, and various wastes in dredged materials. According to these characteristics, the construction schemes commonly used for dredging small and medium-sized rivers in cities include building cofferdams to discharge river water and dredging underwater by ships. Among them, dry dredging, mud pump dredging and hydraulic flushing dredging are divided into cutter suction dredger, grab dredger and bucket wheel dredger according to different equipment [3]. The classification is shown in figure 1.
2. 1 main ditch dredging
Main canal dredging refers to the construction of temporary cofferdam to discharge part of the river water and carry out construction in the main canal area. Among them, the construction methods suitable for dredging dry tanks are divided into dry excavation, mud pump and hydraulic flushing excavation [4].
2. 1. 1 dry excavation and dredging refers to the direct excavation of the drained operation area by an excavator, and the excavated sludge is directly transported away by a muck truck or placed at a temporary stacking point on the shore. When the water content of sludge is large, the water content of sludge can be controlled by drying or mixing soil. The advantages of dry dredging method are intuitive and thorough dredging, low requirements for equipment and technology, low water content of sludge and easy subsequent treatment.
2. 1.2 Dredging by mud pump Dredging by mud pump means that after simple manual cleaning of river garbage, mud is directly transported to coastal spoil ground by mud pump. Mud pump method is suitable for dredging in narrow sections of rivers. Its advantages are convenient equipment configuration, integration of excavation, transportation and suction, and good construction quality. However, it is necessary to manually clean up the river garbage in the early stage, otherwise it will affect the operation of the equipment.
2. 1.3 dredging by hydraulic flushing means that high-pressure water guns are used to scour the bottom mud, so that the mud is collected in a preset low-lying place, then pumped by a mud pump, transported by pipelines, and then transported to the storage yard or mud collection pool on the shore. Hydraulic scouring method is especially suitable for rivers with hardened river bottom, which can protect the hardened river bottom from mechanical damage. However, compared with dry dredging, this method has low mud concentration and is not convenient for subsequent treatment.
Based on the above three construction methods, dry river dredging is suitable for rivers with small flow, which has the advantages of intuitive construction conditions and easy quality assurance, and can also solve the problem that dredged objects contain complex garbage. The disadvantage is that many rivers can only be constructed in non-flood season due to the discharge of running water in the river, and the construction period is limited to some extent. At the same time, it increases the cost of temporary cofferdam construction, and the entry and exit of mechanical vehicles will also have a certain impact on river slope and ecosystem, which needs to increase the cost of slope repair in the later stage.
2.2 Underwater dredging
Underwater dredging refers to assembling dredging equipment on the ship with a certain water depth and operating the dredging equipment on the water surface to excavate silt. Underwater dredging can use cutter suction dredger, grab dredger and bucket wheel dredger.
2.2. 1 cutter suction dredger uses the rotary motion of the cutter installed at the front of the cab in front of the ship to cut and stir the sediment in the riverbed and mix the mud and water to form mud. Through the suction vacuum generated by the ship's centrifugal pump, the mud enters the suction end of the mud pump along the mud suction pipe and is transported to the storage yard through the fully enclosed pipeline. Cutter suction dredging is a kind of construction technology which integrates excavation, transportation and blowing. Fully enclosed pipeline is used to transport mud, which will not cause mud scattering or leakage. However, low mud concentration will increase the amount of mud and the area of mud yard.
2.2.2 Grab dredger Dredging Grab dredger reaches into the bottom of the river through the grab bucket on the front arm of the dredger, uses oil pressure to drive the grab bucket to insert the bottom mud, closes the bucket to grab the underwater mud, then lifts the swing to open the grab bucket, and directly unloads the mud into the barge berthed beside the dredger, so as to carry out excavation, swinging and mud unloading cycle operations. The cleaned sludge is transported to the sludge yard by barge. Grab dredgers are flexible and not affected by obstacles such as garbage and stones in the river. They are suitable for digging hard earthwork or earthwork with more impurities and garbage in the middle. However, the grab dredger has poor sensitivity to extremely weak sediment, which easily leads to the floating mud on the surface being stirred and returning to the water.
2.2.3 Bucket wheel dredger Dredging Bucket wheel dredger uses special bucket wheel excavator to excavate underwater mud, and the excavated mud is pumped by the high-power mud pump on the dredger and enters the mud conveying pipeline. It is transported to the designated mud unloading area through a fully enclosed pipeline. Similar to cutter suction dredger, fully enclosed pipeline is used to transport mud, which will not cause mud scattering or leakage. However, the bucket wheel is seriously dredged and silted, and the dredging is not thorough enough, which is easy to cause large-scale water pollution. Based on the above three construction methods, underwater dredging by mechanical ship is suitable for rivers with thick silt layer. Its advantages are that the construction process is not affected by the weather, and the dredging process will not affect the navigation of the river, so the construction accuracy is high; The disadvantage is that due to the strong agitation of sediment, it is easy to cause the diffusion of pollutants in sediment, and the phenomenon of sediment escape and deposition is also serious. Generally speaking, the dredging effect is the most obvious when the river can be partially drained, and the small dredging boat can also be an option when the river can not be drained.
3 building applications
3. 1 project overview
The Qinghe River originates from Biyun Temple in Xishan, Beijing, flows through Haidian District, Chaoyang District and Changping District, passes through Zhongguancun Science Park, is close to the Fifth Ring Road and the Olympic Forest Park, and flows into Wenyu River in Shunyi District, with a total length of 23.6km. The basin reaches Xisanqi in the north, Xizhimen in the south, Yuquan Mountain in the west and Wenyu River in the east, with a total drainage area of 2 10/0000 m2. It is a drainage channel for major cities in northern Beijing. The main tributaries are North Han River, Wanquan River, Xiaoyue River, Yangshan Gully and Dongxiaokou Gully. Qinghe has planned a 20-year flood flow 158~556m3/s, and a 50-year flood flow190 ~ 690m3/s. After years of operation, a large amount of muck and silt appeared in the river, which seriously affected the flood safety and landscape environment of the river. In order to harness the Qinghe River, ensure the flow capacity, create a good water environment and build a livable ecological environment, it is necessary to carry out the dredging project construction of the Qinghe River.
3.2 Dredging Scheme Analysis
The main task of this project is to dredge the fifth reach of Qinghe River with serious siltation and restore the designed section of the river. The following factors should be considered when determining the construction scheme.
1) construction period: the construction period is 201April1~ 201April 20th, which is a non-flood season in Beijing.
2) River conditions: Qinghe River is the drainage channel of major cities in northern Beijing, with shallow water and slow flow rate.
3) Siltation: The average thickness of silt in the project section is 45cm, and the river contains a large amount of muck and a small amount of domestic garbage, so the silt situation is complicated.
4) Sludge piling: It is impossible to pile up sludge near the construction site, so it is necessary to directly load the removed sludge into the muck truck for transportation.
5) External traffic: The external traffic line of the project can be connected by Xunhe Road to Badaling Expressway, North Fifth Ring Road and Heiquan Road. The main foreign materials and construction machinery can be transported to the construction site through the above roads, and the sludge can be transported to the garbage dump through the above roads. According to the above river characteristics and construction conditions, the Qinghe dredging project chooses to build cofferdams to drain part of the river and carry out dredging of the main river. At the same time, the dry excavation method is also adopted, and the excavator enters the river channel to directly excavate silt.
3.3 architecture
During dredging, all sections are cleaned by mechanical and manual cooperation. For this construction, in the preliminary work: measuring fixed points, building construction tracks and car washing pools on both sides of the river, setting cofferdams, and pumping water in the cofferdams, the silt will be collected by excavators (the scattered silt will be collected by manpower), and then it will be transported to the aggregates near the tracks by loaders, and the excavator will mix with the soil according to the ratio of silt: soil = 1:0.5, and finally it will be transported to the muck yard by vehicles for consumption. In order to ensure that the transportation of vehicles will not cause pollution to the urban environment, car washing troughs are set at the entrances and exits of vehicles on the construction site, and non-woven fabrics are laid at the same time, and special personnel are arranged to clean vehicles. Every vehicle carrying muck abroad must be cleaned before it can be released. Cleaning personnel shall be arranged at intervals for muck transportation, and clods and dirt scattered by vehicles shall be cleaned at any time, and special personnel shall be arranged to patrol and be on duty, and traffic at intersections shall be organized.
4 conclusion
The dredging project of small and medium-sized rivers in cities not only has the purpose of traditional dredging, that is, to ensure drainage, flood control and irrigation, but also has the deep purpose of improving river water quality, promoting ecosystem health and enhancing river landscape. Therefore, it is necessary to ensure the characteristics of this kind of dredging from all aspects, such as preliminary work, scheme formulation, process selection and project implementation. In the case of various dredging methods, according to the characteristics of Qinghe river course and water flow, various aspects are analyzed and demonstrated, and the dredging method of "dry excavation dredging method" is successfully adopted to achieve the purpose of dredging Qinghe River, and good results have been achieved, achieving the goal of "clean shore, smooth circulation, ecological health and harmony between people and water". It has accumulated experience for dredging small and medium-sized rivers in cities.
refer to
[1] Zhang Xiaolan. Problems and countermeasures of small and medium-sized rivers management in China [J]. Research on water conservancy development, 2005( 1):68-70.
[2] Jianping Bao. Dredging and sludge treatment technology in the regulation of small and medium-sized rivers [J]. Water resources protection, 2015,31(1): 56-68.
Shen ... On several construction schemes of small-scale river dredging project [J]. Journal of Zhejiang University of Water Resources and Hydropower, 20 1 1, 23(4):45-57.
Yang Min. Research and application of sediment detector for small and medium rivers in cities [D]. Anhui: Anhui Agricultural University, 20 12.
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