阅读说明：本技术 一种将疏浚底泥用于滨岸生态带建设的施工工艺 (Construction process for applying dredged sediment to construction of coastal ecological zone ) 是由 钟瑞 袁宝来 励彦德 张全胜 于 2021-07-14 设计创作，主要内容包括：本发明涉及一种将疏浚底泥用于滨岸生态带建设的施工工艺。包括以下步骤：(1)在河湖滨岸生态带打设钢板桩形成条带状封闭围堰；(2)在河湖内实施环保疏浚吹填施工工艺,将疏浚底泥输送至围堰内；(3)对围堰排水口溢流出的尾水进行处理；(4)钢板桩围堰内的疏浚底泥静置沉淀后,进行电渗联合真空预压快速脱水；(5)根据自然岸坡坡度及生态恢复要求,进行地形整理；(6)根据施工季节种植并回收挺水植物,实现对底泥的生态处置；(7)生态修复完成后,拆除钢板桩围堰,形成自然生态湿地。本发明实现了疏浚底泥在滨岸生态带建设方面的应用,消除内源污染并对底泥减容减量处理,实现营养物质的胶结封存并采用挺水植物实现生态恢复。(The invention relates to a construction process for applying dredged sediment to construction of a shore ecological zone. The method comprises the following steps: (1) steel sheet piles are driven on ecological zones of the riverside and the lake shore to form a strip-shaped closed cofferdam; (2) carrying out an environment-friendly dredging hydraulic fill construction process in rivers and lakes, and conveying dredged sediment into a cofferdam; (3) treating tail water overflowing from a drainage port of the cofferdam; (4) after the dredged sediment in the steel sheet pile cofferdam is stood and precipitated, carrying out electroosmosis combined vacuum preloading and rapid dehydration; (5) performing terrain arrangement according to the slope of the natural bank slope and the ecological restoration requirement; (6) emergent aquatic plants are planted and recovered according to the construction season, so that ecological treatment of bottom mud is realized; (7) and after the ecological restoration is finished, removing the steel sheet pile cofferdam to form the natural ecological wetland. The invention realizes the application of the dredged sediment in the construction of the coastal ecological zone, eliminates endogenous pollution, reduces the volume and the amount of the sediment, realizes the cementing and sealing of nutrient substances and adopts emergent aquatic plants to realize ecological restoration.)

1. A construction process for applying dredged sediment to construction of a shore ecological zone is characterized by comprising the following steps: comprises the following steps of (a) carrying out,

(1) steel sheet piles are driven on ecological zones of the riverside and lake shore to form a strip-shaped closed cofferdam, and an overflow drainage port is arranged on the steel sheet pile cofferdam;

(2) carrying out an environment-friendly dredging hydraulic fill construction process in rivers and lakes, and conveying dredged sediment into a steel sheet pile cofferdam;

(3) treating tail water overflowing from a drainage port of the steel sheet pile cofferdam, and discharging the tail water into a river and lake water body after the tail water is qualified and meets the environmental protection discharge requirement;

(4) after the dredged sediment in the steel sheet pile cofferdam is kept stand and deposited, electro-osmosis combined vacuum preloading rapid dehydration is carried out, and a dehydration device is recovered after dehydration is finished to remove exogenous pollutants caused by dehydration construction;

(5) performing terrain arrangement according to the slope of the natural bank slope and the ecological restoration requirement;

(6) emergent aquatic plants are planted and recovered according to the construction season, nitrogen and phosphorus pollutants in the bottom sludge are absorbed, and ecological treatment of the bottom sludge is realized;

(7) and after the ecological restoration is finished, removing the steel sheet pile cofferdam to form the natural ecological wetland.

2. The construction process for using the dredged sediment for the construction of the coastal ecozone as claimed in claim 1, which is characterized in that: in the step (3), tail water treatment equipment is matched with a pond chain settling zone to carry out tail water treatment; the tail water treatment equipment comprises dosing and stirring equipment, the pond chain settling zone comprises a plurality of settling ponds arranged in a chain manner, and tail water treatment is carried out in each settling pond in a mode of combining interception by a sewage blocking screen, overflow settling, settling by an enlarged flow path and coagulation promoting treatment settling.

3. The construction process for applying the dredged sediment to the construction of the coastal ecozone as set forth in claim 2, wherein: and (4) drilling a plurality of groups of electroosmosis anode plates and cathode plates in the sediment, connecting the electroosmosis anode plates and the electroosmosis cathode plates to a power supply device, arranging a drainage plate and a drainage pipe in the sediment, covering a sealing film on the mud surface, and vacuumizing the space below the film.

4. The construction process for using the dredged sediment for the construction of the coastal ecozone as claimed in claim 3, which is characterized in that: the emergent aquatic plant in the step (6) is selected to be reed.

Technical Field

The invention belongs to the technical field of environment-friendly dredging construction, and particularly relates to a construction process for applying dredged sediment to construction of a coastal ecological zone, which is mainly applied to the fields of river and lake endogenous pollution treatment, environment-friendly dredging, sediment dehydration treatment, resource utilization and the like.

Background

As rivers and lakes in China are numerous and the economy is rapidly developed, nutrient substances flowing into the lakes are gradually deposited at the bottoms of the rivers and lakes through various physical, chemical and biological actions. Part of nutrient substances such as nitrogen, phosphorus and the like accumulated in the bottom mud can be directly ingested by microorganisms and enter a food chain to participate in the circulation of an aquatic ecosystem; the other part is released from the bottom mud to enter the water again under certain physical, chemical and environmental conditions, thereby forming the endogenous pollution of rivers and lakes. Environmental-friendly dredging is one of effective strategies for solving the problem of endogenous pollution treatment of rivers and lakes, and the technology is mature and is generally applied.

The environmental protection dredging is the earth and stone engineering which adopts a dredger or other machines and manual work to excavate underwater and is carried out for widening and deepening water areas. The design stress diagram of the dredging engineering trenching causes the change of the internal structure of the water flow by changing the geometric boundary of the water flow of the river channel, so that the newly formed water flow structure can not only ensure that the silt is not deposited in the channel, but also convey the silt entering the trenching into the lower deep groove, and maintain the stability of the channel. Dredging engineering is an engineering for excavating and treating water bottom sediment, sand, stones and the like in a water area of a channel or a port according to a specified range and depth, and one of main means for developing, improving and maintaining the water area of the channel or the port.

The bottom mud treatment mode is determined according to project working conditions, the mud receiving pit can select a natural airing dehydration mode and a vacuum preloading dehydration mode for a hydraulic filling pit, the soil receiving pit is not provided, but a soil bag dehydration volume reduction process can be selected for large-area leveling open space, and the pit and the large-area open space can be selected to be suitable for mechanical dehydration in a field station. The natural airing dehydration is greatly influenced by weather and underground water level mainly through ways of sunlight evaporation, air drying, natural infiltration and the like, the organic matter content of the environment-friendly dredged sediment is high, the particles are fine, the evaporation and infiltration discharge of the lower middle part of the slurry are difficult, the natural airing dehydration generally needs 2-3 years, and the dehydration effect is poor; the vacuum prepressing dehydration forms a drainage channel by arranging a vertical drainage plate, forms vacuum negative pressure under the film covering and pumping drainage, can quickly remove water in the dredged sediment compared with natural airing, but takes 3 months for long time, has large energy consumption, relatively poor dehydration effect, low upper part, middle part and lower part of water content, the dehydrated sediment is easy to reduce by water bubbles, and substances such as nitrogen, phosphorus and the like in the sediment are easy to release; the geotechnical pipe bag dehydration volume reduction process solves the problem of large-scale continuous dredging sediment rapid dehydration under the condition of pond-free blowing filling, has working condition adaptability, but comprises site construction, dosing conditioning, pipe bag dehydration, tail water treatment, outward transportation of the dehydration sediment, site recovery and the like, has more construction links, higher construction cost, more environmental influence factors, uneven dehydration effect, lower exterior and higher interior, and the dehydration sediment is exposed in natural environment and is easy to restore through water bubbles; the mechanical dehydration mode comprises mechanical filter-pressing dehydration and centrifugal dehydration, the mechanical filter-pressing dehydration comprises plate-frame filter-pressing dehydration and belt-type press dehydration, the mechanical dehydration equipment effectively solves the difficult problem of dehydration of the dredged sediment under the conditions of no mud receiving pit and large-scale field, and the mechanical dehydration equipment has the characteristics, applicability and limitation. Mechanical squeezing dehydration all need remove the gred and add the medicine and take care of to mud before the filter-pressing to protection equipment extension life cycle and accelerate the sediment dehydration, the conditioner is the flocculating agent, and filter aid or curing agent need be added to the plate and frame filter-pressing mode, and dehydration speed is fast, the water content is even relatively, and belt filter press and centrifuge dehydration sediment water content are higher, and the dehydration sediment is easily restoreed through the blister, and the plate and frame filter press is owing to added filter aid or curing agent, and the resource utilization scope of sediment is less.

With the progress of urbanization and the continuous development of endogenous pollution control, the pool sites for receiving mud are less and less, and flood control safety, environmental protection and ecological protection put higher requirements on the construction technology of endogenous pollution control. With the great development of the environmental protection construction technology and the ecological environmental protection concept, the construction of an ecological zone in the shore area of a river becomes an important environmental protection measure. The shore ecological zone is used as a buffer zone between human activities and rivers and plays an important role in restoring the river ecology. The dredging sediment in the river dredging construction is used for constructing the coastal ecological zone, the dredging sediment is processed nearby, the dredging sediment processing cost is reduced, the dredging sediment is used as a component of the coastal ecological zone, the construction cost of the coastal ecological zone can be reduced, and the method is a processing mode with remarkable income. Under the situation, a construction process which can meet the requirements of endogenous pollution control, environmental protection and dredging construction and can also meet the requirements of harmlessness, reduction, reclamation and ecological environmental protection of dredged sediment is urgently needed.

Disclosure of Invention

The invention provides a construction process for applying dredged sediment to construction of a shore ecological zone for solving the technical problems in the known technology, overcomes the dilemma that no pool or yard is arranged and no open land is used for dewatering in the environment-friendly dredging of the endogenous pollution treatment of urban rivers and lakes, solves the technical problems of safety, environment friendliness, quick dewatering treatment, harmlessness, reduction, resource treatment and the like of the dredged sediment, and realizes the application of the dredged sediment of rivers and lakes in the construction of the river shore ecological zone engineering.

The technical scheme adopted by the invention for solving the technical problems in the prior art is as follows: a construction process for applying dredged sediment to construction of an ecological zone on a shore comprises the following steps: (1) steel sheet piles are driven on ecological zones of the riverside and lake shore to form a strip-shaped closed cofferdam, and an overflow drainage port is arranged on the steel sheet pile cofferdam; (2) carrying out an environment-friendly dredging hydraulic fill construction process in rivers and lakes, and conveying dredged sediment into a steel sheet pile cofferdam; (3) treating tail water overflowing from a drainage port of the steel sheet pile cofferdam, and discharging the tail water into a river and lake water body after the tail water is qualified and meets the environmental protection discharge requirement; (4) after the dredged sediment in the steel sheet pile cofferdam is kept stand and deposited, electro-osmosis combined vacuum preloading rapid dehydration is carried out, and a dehydration device is recovered after dehydration is finished to remove exogenous pollutants caused by dehydration construction; (5) performing terrain arrangement according to the slope of the natural bank slope and the ecological restoration requirement; (6) emergent aquatic plants are planted and recovered according to the construction season, nitrogen and phosphorus pollutants in the bottom sludge are absorbed, and ecological treatment of the bottom sludge is realized; (7) and after the ecological restoration is finished, removing the steel sheet pile cofferdam to form the natural ecological wetland.

The invention has the advantages and positive effects that:

compared with the prior dredging sediment treatment mode, the construction process for applying the dredging sediment to the construction of the coastal ecological zone realizes the application of the dredging sediment to the construction of the coastal ecological zone by constructing the coastal ecological zone in the coastal area of the riverway and using the dredging sediment as the foundation of the coastal ecological zone. The process does not reduce the area of the water area after construction, realizes the technical effect of removing and transferring large-area sediment in the construction water area through environment-friendly dredging construction to eliminate endogenous pollution, increases the water area storage capacity of rivers and lakes through centralized dehydration, volume reduction and decrement treatment after sediment displacement, and better meets the treatment requirement. By adopting the electroosmosis and vacuum preloading dehydration technology, the chemical reactions such as pore water seepage, physical dehydration consolidation, oxidation-reduction reaction, ion exchange reaction and the like in the sludge are realized, the sediment is further consolidated under the cementing action, the molecular structure of sediment particles is changed to realize cementing and sealing of nitrogen and phosphorus nutrient substances, and the sediment is subjected to harmless treatment under the condition of not adding any medicament. The emergent aquatic plants are adopted for ecological restoration, so that the emergent aquatic plants can absorb nitrogen and phosphorus, can be recycled, drive local economic development, increase employment opportunities, realize the win-win effect of ecological restoration and economic development and have certain popularization value.

Preferably: in the step (3), tail water treatment equipment is matched with a pond chain settling zone to carry out tail water treatment; the tail water treatment equipment comprises dosing and stirring equipment, the pond chain settling zone comprises a plurality of settling ponds arranged in a chain manner, and tail water treatment is carried out in each settling pond in a mode of combining interception by a sewage blocking screen, overflow settling, settling by an enlarged flow path and coagulation promoting treatment settling.

Preferably: and (4) drilling a plurality of groups of electroosmosis anode plates and cathode plates in the sediment, connecting the electroosmosis anode plates and the electroosmosis cathode plates to a power supply device, arranging a drainage plate and a drainage pipe in the sediment, covering a sealing film on the mud surface, and vacuumizing the space below the film.

Preferably: the emergent aquatic plant in the step (7) is selected to be reed.

Detailed Description

In order to further understand the contents, features and effects of the present invention, the following embodiments are described in detail.

The construction process of the invention for applying the dredged sediment to the construction of the coastal ecological zone comprises the following steps,

(1) steel sheet piles are driven on ecological zones of the riverside and lake shore to form a strip-shaped closed cofferdam, and an overflow drainage port is arranged on the steel sheet pile cofferdam;

the shore ecological zones of the rivers and the lakes are positioned near an operation water area for environment-friendly dredging construction, and construction operation of the steel sheet pile cofferdam is carried out at a selected position to form a closed strip-shaped cofferdam structure. And a water outlet arranged on the steel sheet pile cofferdam is used for discharging internal tail water, the bottom mud slurry obtained by the environment-friendly dredging operation is injected into the cofferdam area, and the bottom mud is precipitated after the tail water is discharged.

(2) Carrying out an environment-friendly dredging hydraulic fill construction process in rivers and lakes, and conveying dredged sediment into a steel sheet pile cofferdam;

in the step, the existing environment-friendly dredging process is performed, specifically, environment-friendly dredging is performed on the operation water area by adopting environment-friendly dredging equipment such as an environment-friendly dredging boat and the like, the environment-friendly dredging equipment excavates the bottom sediment and transfers the obtained dredging sediment, and the dredging sediment is transferred and conveyed into the steel sheet pile cofferdam.

Endogenous pollution mainly refers to the phenomenon that nutrient substances entering rivers gradually settle to the surface layer of a bottom substrate of the water through various physical, chemical and biological actions and are released to a water body after accumulating to a certain amount. Therefore, the surface layer of the underwater mud surface is removed by implementing the environment-friendly dredging process in the step, the removal of the internal pollution is realized, and the requirement of environment-friendly treatment on rivers and lakes is met.

(3) Treating tail water overflowing from a drainage port of the steel sheet pile cofferdam, and discharging the tail water into a river and lake water body after the tail water is qualified and meets the environmental protection discharge requirement;

in the step, tail water treatment equipment is adopted to be matched with a pond chain settling zone for tail water treatment, wherein the tail water treatment equipment comprises dosing and stirring equipment, the pond chain settling zone comprises a plurality of settling ponds which are arranged in a chain manner, and tail water flows through the settling ponds step by step.

And tail water treatment is carried out in each sedimentation mud pond by adopting a mode of combining interception by a trash screen, overflow sedimentation, sedimentation by increasing a flow path and coagulation-promoting treatment sedimentation. Specifically, a sludge blocking screen is arranged in the sludge pond, when tail water flows through the sludge blocking screen, the contained particulate impurities are blocked, a flocculating agent is added into the tail water by the dosing and stirring equipment, the tail water is stirred to promote flocculation and precipitation of components in the tail water, and the tail water after coagulation promotion treatment overflows from the sludge pond along with increase of the tail water to generate a precipitation effect. The precipitation with the increased flow path is also called radial flow precipitation, namely tail water flows radially, and the water section is gradually increased along with the flow, so that the flow velocity is reduced, and the precipitation is easier.

(4) After the dredged sediment in the steel sheet pile cofferdam is kept stand and deposited, electro-osmosis combined vacuum preloading rapid dehydration is carried out, and a dehydration device is recovered after dehydration is finished to remove exogenous pollutants caused by dehydration construction;

in this embodiment, the electroosmosis vacuum preloading dehydration process is divided into two aspects, on one hand, a plurality of groups of electroosmosis anode plates and cathode plates are arranged in the sediment and connected to a power supply device, the electroosmosis dehydration process is executed, on the other hand, a drainage plate and a drainage pipe are arranged in the sediment, a sealing film is covered on the mud surface, and the vacuum preloading dehydration process is executed by performing vacuum pumping on the space below the film by using equipment such as an air extractor.

The electroosmosis dehydration process is a treatment method which can effectively remove moisture in bottom sludge to realize volume reduction and weight reduction, and the principle is as follows: with the development of the dehydration effect from the anode to the cathode, the sediment can be divided into dehydrated sediment and non-dehydrated sediment, electroosmosis in the dehydrated sediment stops, and the electroosmosis and moisture removal occur in the non-dehydrated sediment and are determined by the voltage gradient of the non-dehydrated sediment; the resistance value of the dewatered bottom mud is increased, so that the voltage gradient of the non-dewatered bottom mud is gradually reduced, the electroosmotic flow and the dewatering effect are attenuated, and the residual moisture content of the bottom mud is gradually increased from the anode to the cathode; the integral effect of electroosmosis dehydration is improved along with the increase of the loading voltage, the dehydration energy consumption is increased along with the increase of the loading voltage, and the electroosmosis dehydration energy efficiency is improved when a smaller electrode distance is selected.

The principle of the vacuum preloading dehydration process is as follows: when the air exhaust operation is carried out on the space between the lower part of the film and the mud surface, a negative pressure environment is formed under the film, and then the water in the bottom mud layer enters the drainage plate and the drainage pipe and is finally discharged.

The vacuum preloading dehydration process has the main effect of dehydrating the bottom mud, the electroosmosis dehydration process realizes physical dehydration and consolidation after pore water seepage and a series of chemical cementation effects such as redox reaction, ion exchange reaction and the like under the effect of an electric field besides dehydrating the bottom mud, changes the molecular structure of bottom mud particles, and realizes cementation and sealing of nitrogen-containing and phosphorus-containing components originally used as pollutants, so that harmless treatment is realized under the condition of not adding any medicament.

(5) Performing terrain arrangement according to the slope of the natural bank slope and the ecological restoration requirement;

in the step, the landform is arranged, so that the construction area in the cofferdam meets the requirements of the slope of the natural bank slope and the ecological restoration. Specifically, the sediment is transferred and moved in the step in a mode of combining manpower and machinery, namely, the sediment which needs to form a low position is transferred to a position which needs to form a high position, so that the terrain arrangement operation is realized.

(6) Emergent aquatic plants are planted and recovered according to the construction season, nitrogen and phosphorus pollutants in the bottom sludge are absorbed, and ecological treatment of the bottom sludge is realized;

in the embodiment, the emergent aquatic plants are selected from the reeds, the reeds have strong capability of absorbing nitrogen and phosphorus and are natural enemies of blue-green algae, and the reeds have certain economic value, such as reed leaves supplied to a rice dumpling factory, and the reed straws can be crushed and compressed into fuel after being harvested or directly burned to generate electricity for resource utilization in connection with a power plant.

(7) After the ecological restoration is finished, removing the steel sheet pile cofferdam to form a natural ecological wetland;

judging whether the ecological restoration is finished or not according to the detection of the water quality, the soil quality, the vegetation and the like in the steel sheet pile cofferdam; after the steel sheet pile cofferdam is removed, the internal area is combined with the surrounding water body and land area to form a natural ecological wetland which is used as an important component of the shore ecological zone.