Construction method for repeatedly utilizing dredged soil waste

Abstract

The invention discloses a construction method for repeatedly utilizing dredged soil waste. The construction method sequentially comprises the steps that a harbor basin is dredged in a striping and layering mode through a grab dredger, and dredged soil is conveyed to a self-propelled mud barge and conveyed to a cofferdam construction area; dredged soil is used for carrying out hydraulic reclamation on the bagged sand cofferdam, and a temporary cofferdam structure is formed; dredged soil is blown and filled into the cofferdam to form an island building construction platform; wharf pile foundation and trestle construction is conducted on the island building platform; foundation treatment and backfill construction of land roads and storage yards are synchronously implemented; dismantling the temporary cofferdam, and recovering bagged sand and dredger fill of the cofferdam; the recycled material is mixed with a curing agent to produce solidified soil for land area backfilling. The method solves the problems that earthwork generated by a dredging mode in the prior art is prone to causing waste of a large amount of resources, and the disposal cost is gradually increased along with site shortage, and has the advantage that dredging engineering and water area island building construction engineering can be combined, so that resource recycling is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of water area treatment, and particularly relates to a construction method for recycling dredged soil waste multiple times. Background Art

[0002] With the rapid development of global port waterway maintenance, river regulation, and coastal engineering construction, the scale of dredging projects has been continuously expanding. According to statistics, the annual volume of dredged soil in China has exceeded 1 billion cubic meters. The traditional disposal methods mainly use ocean dumping or land stacking, but there are significant limitations. The receiving sites are becoming increasingly scarce, and the transportation and stacking costs account for a relatively high proportion of the total project cost, resulting in resource waste and ecological pressure. There are also some dredged soils used in temporary engineering construction, etc., but there are obvious defects. There is no secondary utilization channel for temporary projects, resulting in more than 90% of the soil eventually becoming construction waste. Therefore, a construction method for recycling dredged soil waste multiple times is needed to solve the above problems. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a construction method for recycling dredged soil waste multiple times, aiming to solve the problems that the soil generated by the existing dredging methods is likely to cause a large amount of resource waste and the disposal cost is increasing day by day due to the shortage of sites. It has the characteristics of combining the dredging project with the water area island construction project, so as to realize resource recycling.

[0004] To solve the above technical problems, the technical solution adopted by the present invention is: A construction method for recycling dredged soil waste multiple times, comprising the following steps: S1, Dredge the port basin by a grab dredger in strips and layers, transport the dredged soil to a self-propelled hopper barge and transport it to the cofferdam construction area; S2, Use the dredged soil for the reclamation of the sand-filled cofferdam to form a temporary cofferdam structure; S3, Fill the inside of the cofferdam with dredged soil to form an island construction platform; S4, Carry out the construction of the wharf pile foundation and the trestle on the island platform; S5, Synchronously implement the foundation treatment and backfilling construction of the land road and yard; S6, Demolish the temporary cofferdam, recycle the sand-filled bags and the dredged soil in the cofferdam; S7, Incorporate the recycled materials into a curing agent to produce solidified soil for land backfilling.

[0005] Preferably, in step S2, using the dredged soil for the reclamation of the sand-filled cofferdam includes: S201, Processing, sewing, and transporting the geotextile. The processing and sewing of the geotextile are completed in the geotextile processing yard, and then it is shipped to the construction ship through the material shipping wharf; S202, Construction of the sand-filled bags: When laying underwater, the construction technology of pulling and filling with sand bags in bags is adopted. When the sand bags are laid out of the water surface, the land-based manual laying of the bag body combined with the filling technology of the sand blowing ship is adopted.

[0006] Furthermore, in step S201, the processing, sewing and transportation of geotextiles are completed in the geotextile processing yard, and then shipped to the construction ship through the material shipping dock. The specific method is as follows: Layout marking: The qualified geotextiles are marked according to the designed width and length of the bag body, and cut according to the layout dimensions; Bag body sewing: The cut single pieces are sewn into bags by the overlock sewing method of industrial sewing machines; in order to facilitate the insertion of the sand conveying pipe for filling and make the thickness of the sand layer uniform, when processing the bag body, a row of filling cuffs will be sewn every 4 - 5 m along the length direction of the bag body; Inspection, packing and warehousing: After the bag body is processed and inspected qualified, it is packed and transported to the finished product warehouse, and an inventory receipt is filled out, stating the specifications, models, used parts and processing dates, and preparing an outbound note for outbound use; After the processing and sewing of the geotextiles are completed, they are rolled up with a winch using a steel pipe as the shaft, then labeled and registered and stored for transportation; the transportation is carried out by a flatbed truck to transfer the geotextiles from the processing yard to the shipping dock, and then transferred to the construction ship by an anchor boat or a transport ship on the water; Furthermore, the specific method of the construction technology of pulling and filling with sand bags in bags is as follows: (1) Construction of filling the bag body: According to the designed structural dimensions, the filling bags are designed in layers according to the requirements and the construction capacity of the equipment, processed into rectangles, the cross-sectional width of which is based on the cross-section of the sand bag, and the axial length is taken according to the design drawing; the bag body is manufactured in the geotextile processing yard, made by a special sewing group, and inspected by a quality inspector; (2) Positioning of the pulling boats: The pulling boats adopt engineering boats with relatively flexible mobility. The pulling boats are stationed at a position 20 m horizontally from the outer edge of the bag body for each planned filling construction. The pulling boats are moved to the designated area, accurately positioned by RTK, and equipped with an anchor boat to cast two eight-shaped anchor cables in the front and rear to fix the boats; (3) Pulling and spreading the filling bag body: This project is located inside the gate sluice. The water area is narrow, there are basically no waves, and the water flow velocity is small, with a maximum value of 0.2 m / s. The processed geotextile filling bags are transported by a transport ship to the side of a pair of pulling boats. Each pair of pulling boats is respectively connected to two corner points at one end of the bag with two nylon ropes with sufficient pulling force (loose knots), and the other ends of the nylon ropes are fixed on the winches of the pair of pulling boats. When laying and positioning the bags, a 2-m overlap is considered between adjacent bags in the same layer. The opposite pair of pulling boats start the winches to pull the bags to the water surface and gradually unfold them. The bags are displaced to the pre-settlement position by tightening and loosening the nylon ropes with the winches of the two boats. After the surveyors use RTK to accurately review and check the positions of the four corners, the nylon ropes are tightened to fix the bags. After the bags are positioned, in order to facilitate the inspection of the position after filling and sinking, floating buoys are tied to the four corners of the bags in advance.

[0007] Furthermore, the specific method of the onshore manual bag laying combined with the sand filling process by a sand dredging boat is as follows: (1) Filling operation: The sand dredging boat fills the sea sand into the filling bags through the conveying pipelines laid at sea. The sand conveying pipes adopt high-strength plastic pipes with a diameter of 400 mm and rubber hoses. The high-strength plastic pipes are laid in the form of sunken pipes and float to the water surface after reaching the site. Then, the main pipe is branched into multiple branch pipes through a flow divider, and the flow divider is installed on the floating boat. The branch pipes are connected to the cuffs of the bags with 6-inch acrylic hoses and extend into the cuffs (extend into the bags) and are firmly tied. During the laying process of the sand conveying pipelines, the connection quality is strictly controlled to ensure that there are no running, leaking, dripping, or overflowing phenomena during the entire construction process. After the branch pipes are connected to the cuffs, the high-pressure water guns on the sand dredging boat are turned on to scour and stir the sand and soil in the sand transport cabin. The hydraulic dredging unit sucks the sand from the sand transport cabin, transports it through the conveying pipeline to the filling site, and is filled into the sand filling bags after being branched by the flow divider. When filling, the four corners of the bags are filled first, and the nylon ropes are loosened while filling to slowly sink the filling bags. After the bags are filled and sunk in place, finally, the nylon ropes and the anchor ropes are untied. During the filling process, the surveyors should often measure the water depth at the position of the bags, calculate the height of the sand and soil accumulation in the bags, and timely change the position of the filling cuffs. By continuously adjusting the sand filling ports, the sand in the bags is filled evenly and fully, ensuring smooth filling and accelerating the drainage consolidation speed of the bags. When the entire sand bag reaches the stage of slurry screening, the sand filling bag equipment is appropriately reduced or the filling is suspended to prevent the cloth bag from bursting, leaving a certain consolidation and dehydration time. If the ideal height cannot be reached in one filling during the filling process, after the sand bags are slightly consolidated, secondary or multiple fillings are carried out. During the construction process, if any damage is found, the filling must be stopped immediately, and the bags and the filling should be re-laid. Determine the construction position of the next sand quilt bag according to the actual coordinate position of the previous sand quilt, input it into the computer to generate a new electronic nautical chart, and lay the next sand quilt bag under the guidance of GPS, and so on until all the tasks of the sand quilt are completed; (2) Onshore sand bag filling: Bag processing: The bagged sand bags (350g / ㎡ woven non-woven composite geotextile) for this project are all pre-processed in a specialized geotextile processing factory according to the dimensions required by the design; Transportation of the bags: The geotextile bags for this project are transported to the construction site by water + land transportation, and randomly inspected together with the supervising engineer. Materials that do not meet the requirements are returned; Laying of the bags: Before laying the bags, understand the terrain where the geotextile bags will be laid, and lay them manually according to the design drawings. The geotextile bags are laid according to the positioning, and marked and fixed with a benchmark; Positioning of the sand blowing ship: According to the requirements of the construction progress, the sand blowing ship reasonably arranges the cofferdam construction plan, accurately positions according to the plan, erects the mud blowing pipeline and the gun emplacement, and waits for the self-propelled mud barge to dock fully loaded; Incoming of sand materials: The self-propelled mud barge docks at the grab dredger for dredged soil loading operation. After being fully loaded, it sails to the sand blowing ship; Filling of the bagged sand: After the self-propelled mud barge is berthed against the sand blowing ship, the sand blowing ship uses a high-pressure water gun to impact the cabin of the mud barge, and fills the sand into the sand bag through a mud pump. The filling starts from the cuff. When the filling elevation reaches the design requirement, switch to other cuffs to continue filling until the entire bag is filled to the design requirement. During the filling process, pay attention to controlling the uniformity and fullness of the sand bag. After several consecutive fillings, when the sand bag is filled to 60% - 80%, stop filling the sand bag.

[0008] Preferably, in step S3, blowing dredged soil into the cofferdam to form an island construction platform includes: S301, select a sand suction ship according to the construction requirements; S302, lay out the sand blowing pipeline, floating pipe on the water, shore pipe, sand outlet nozzle and water gate; S303, carry out the blowing and filling operation: The grab of the grab dredger grabs the dredged soil to be dredged and dumps it into the self-propelled mud barge, and transports it to the side of the sand blowing ship through the self-propelled mud barge; the sand blowing ship forms a sand suction device through the sand suction pipe, sand suction head and flushing pipe installed on one side of the ship's side. The sand blowing ship loads a large sand suction pump to suck the sand-water mixture from the sand-water mixture in the sand transport ship berthed beside the ship's side, and then transports it to the sand bag and within the cofferdam through the sand discharge pipeline on the other side of the sand blowing ship. After the sand-water mixture precipitates in the filling area, the sand remains in the filling area, and the tail water is discharged from the construction area through the water gate.

[0009] Preferably, in step S4, pile foundation and trestle construction of the wharf are carried out on the island platform, including cast-in-place pile construction, cast-in-place cross beam and capping beam construction, prefabrication and installation of precast components, cast-in-place paving layer construction and anti-corrosion construction.

[0010] Preferably, in step S5, the land reclamation and foundation treatment adopt the precipitation dynamic compaction process, including inserting and driving dewatering pipes to lower the groundwater level, performing point compaction in three passes and surface compaction in one pass, with the compaction energy being 2000 - 2500 kN·m and the surface compaction energy being 800 - 1000 kN·m.

[0011] Preferably, in step S6, the removal of the temporary cofferdam includes: Digging out the riprap at the cofferdam foot and the fill on the cofferdam top, and transporting them to the solidified soil production area by a backhoe excavator in cooperation with a dump truck; using a long-arm excavator to demolish the cofferdam body, recycling sandbags and riprap, and transporting them to the solidified soil mixing plant.

[0012] Preferably, in step S7, incorporating the recycled materials into the solidifying agent to produce solidified soil for land reclamation includes: Before the production of solidified soil, for the soil source with a water content exceeding the set threshold, a new type of dehydration material is used to reduce the water content of the solidified soil; Performing pre-treatment before mixing on the solidified soil with qualified water content, screening the dehydrated solidified soil, and after the screening is completed, sending the solidified soil to a conveyor belt and then to a crusher for crushing, crushing the soil blocks into soil particles with a maximum size not exceeding 15 mm to meet the design particle size requirements of the solidified soil; The crushed soil source then enters a forced mixer through a conveyor belt and is mixed evenly with the solidifying material in the mixing building according to the mixing ratio list required by the design index, and then transported to the in-situ solidification site for filling. The on-site filling adopts the layered rolling process.

[0013] Furthermore, the solidified soil backfilling adopts the layered rolling process, with the virtual paving thickness of each layer being 50 cm and the thickness after rolling being 30 - 35 cm. A roller with a weight of more than 20 T is used for combined rolling of static pressure, weak vibration, and strong vibration.

[0014] Furthermore, the construction of the wharf pile foundation in the fourth step includes: burying steel casing on the island building platform, adopting the slurry-supported bored pile process, with the pile diameter being Φ800 - 1200 mm and the over-pouring height of the pile top being greater than 1 times the pile diameter.

[0015] Furthermore, in the first step, the grab dredger dredging adopts GPS positioning and strip-by-strip and layer-by-layer control, with the grab capacity being 8 m³, and the dredged soil is preferentially used for cofferdam filling and solidified soil raw materials.

[0016] The beneficial effects of the present invention are as follows: 1. The present invention provides a construction method for recycling dredged soil waste multiple times, which can solve the problems that the earthwork generated by the existing dredging method is prone to cause a large amount of resource waste, and the disposal cost is increasing day by day with the shortage of sites. It has the characteristics of combining the dredging project with the water area island building project, so as to realize resource recycling.

[0017] 2. By setting a reasonable construction process, the present invention efficiently transports the soil generated from the dredging project to the cofferdam island construction area in a way that combines land and water transportation. Moreover, by setting different hydraulic filling construction plans for underwater laying and above-water laying, the operation efficiency and construction effect are greatly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a schematic flow chart of the present invention; Figure 2 is a schematic diagram of the dredging and cofferdam island area in an embodiment of the present invention; Figure 3 is a plan layout drawing of the bagged sand cofferdam island in an embodiment of the present invention; Figure 4 is a schematic sectional view of the bagged sand cofferdam island in an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0019] Embodiment 1: As Figure 1 shown, a construction method for recycling dredged soil waste multiple times includes the following steps: S1. Use a grab dredger to dredge the harbor basin in strips and layers, transport the dredged soil to a self-propelled hopper barge, and transport it to the cofferdam construction area; S2. Use the dredged soil for hydraulic filling of the bagged sand cofferdam to form a temporary cofferdam structure; S3. Hydraulically fill the dredged soil into the cofferdam to form an island construction platform; S4. Conduct pier pile foundation and trestle construction on the island platform; S5. Synchronously implement the foundation treatment and backfilling construction of the land-based road and yard; S6. Demolish the temporary cofferdam and recycle the bagged sand and hydraulic fill soil in the cofferdam; S7. Incorporate the recycled materials into a curing agent to produce solidified soil for land-based backfilling.

[0020] As Figure 2 shown, preferably, in step S2, using the dredged soil for hydraulic filling of the bagged sand cofferdam includes: S201. Geotextile processing, sewing, and transportation. The geotextile processing and sewing are completed in the geotextile processing yard, and then it is shipped to the construction ship through the material shipping dock; S202. Bagged sand construction: When laying underwater, the construction technology of pulling and filling bagged sand bags is adopted. When the sand bags are laid above the water surface, the construction technology of manually laying the bag body on land combined with filling by a sand blowing ship is adopted.

[0021] Furthermore, in step S201, the processing, sewing and transportation of geotextiles are completed at the geotextile processing plant, and then shipped to the construction ship through the material shipping dock. The specific method is as follows: Laying out lines: Lay out the qualified geotextiles according to the designed width and length of the bag body, and cut them according to the layout dimensions; Sewing the bag body: The cut single pieces are sewn into bags by using the overlock sewing method of industrial sewing machines; to facilitate the insertion of the sand filling pipe and make the thickness of the sand layer uniform, during the processing of the bag body, a row of filling cuffs will be sewn at intervals of 4 - 5 m along the length direction of the bag body; Inspection, packing and warehousing: After the bag body is processed and passes the inspection, it is packed and transported to the finished product warehouse. An inventory receipt is filled out, stating the specifications, models, used parts and processing dates, and an outbound order is prepared for outbound use; After the processing and sewing of the geotextiles are completed, they are rolled up with a steel pipe as the axis by a winch, then labeled and registered and stored for transportation; for transportation, a flatbed truck is used to transfer the geotextiles from the processing plant to the shipping dock, and then they are transferred to the construction ship by an anchor boat or a transport ship on the water; Furthermore, the specific method of the construction technology of the tensioned filling of the sand-filled bags is as follows: (1) Construction of filling the bag body: According to the designed structural dimensions, the filling bags are designed in layers according to the requirements and the construction capacity of the equipment, and processed into rectangles. The cross-sectional width is based on the cross-section of the sand bag, and the axial length is taken according to the design drawings; the bag body is manufactured in the geotextile processing plant, made by a special sewing group, and inspected by a quality inspector; (2) Positioning of the tensioned boats: The tensioned boats use engineering boats with relatively flexible mobility. The tensioned boats are stationed at a position 20 m horizontally away from the outer edge of the filling bags in each planned filling construction. The tensioned boats are moved to the designated area, accurately positioned by RTK, and equipped with an anchor boat to drop two eight-shaped anchor cables at the front and rear to fix the boats; (3) Tensioned spreading of the filling bag body: This project is located inside the mouth gate sluice, where the water area is narrow, there are basically no waves, and the water flow velocity is small, with a maximum value of 0.2 m / s; the processed geotextile filling bag bodies are transported to the side of a tensioned boat by a transport ship; each tensioned boat is connected to two corner points at one end of the bag with two nylon ropes with sufficient pulling force (loose knot connection), and the other ends of the nylon ropes are fixed on the winches of the tensioned boats; when laying and positioning the bag body, a 2 m overlap is considered between adjacent bag bodies in the same layer. The tensioned boat on the opposite side starts the winch to pull the bag body to the water surface and gradually unfolds it. The position of the bag body is shifted to the pre-settlement position by adjusting the tightness of the nylon ropes by the winches of the two boats. After the four corners are accurately rechecked by the surveyors using RTK, the nylon ropes are tightened to fix the bag body; after the bag body is positioned, in order to facilitate the inspection of the position after filling and sinking, floating buoys are tied to the four corners of the bag body in advance.

[0022] Furthermore, the specific method of the combined process of laying the bag body manually on land and filling it with a sand blowing ship is as follows: (1) Filling operation: The sand blowing ship fills the sea sand into the filling bag through the conveying pipeline laid at sea; the sand conveying pipe adopts a high-strength plastic pipe with a diameter of 400 mm and a rubber hose. The high-strength plastic pipe is laid in the form of a sunken pipe and floats to the water surface after reaching the site, and then the main pipe is divided into multiple branch pipes through a flow divider. The flow divider is installed on the floating ship; the branch pipe is connected to the cuff of the bag body with a 6-inch acrylic hose and extends into the cuff (extends into the bag body) and is firmly tied; during the laying process of the sand conveying pipeline, the connection quality is strictly controlled to ensure that there is no running, leaking, dripping or overflowing phenomenon during the whole construction process. After the branch pipe is connected to the cuff, the high-pressure water gun on the sand blowing ship is turned on to wash and stir the sand and soil in the sand transportation cabin. The hydraulic dredging unit sucks the sand in the sand transportation cabin, transports it through the conveying pipeline to the filling position, and is filled into the filling sand bag after being divided by the flow divider; during filling, the four corners of the bag body are filled first, and the nylon rope is loosened while filling to slowly sink the filling bag. After the bag body is filled and sunk in place, finally untie the nylon rope and the anchor rope; during the filling process, the surveyors should often measure the water depth at the position of the bag body, calculate the height of the sand and soil accumulation in the bag body, and timely change the position of the filling cuff; by continuously adjusting the sand filling port, the sand in the bag is filled evenly and fully, ensuring smooth filling and accelerating the drainage consolidation speed of the bag body; when the whole sand bag reaches the stage of slurry screening, appropriately reduce the sand filling bag equipment or suspend filling to prevent the cloth bag from bursting, and leave a certain consolidation and dehydration time. If the ideal height cannot be reached in one filling during the filling process, after the sand bag is slightly consolidated, carry out secondary or multiple fillings; during the construction process, if damage is found, the filling must be stopped immediately, and the bag body and filling should be re-laid; Determine the construction position of the next sand quilt bag body according to the actual coordinate position of the previous sand quilt, input it into the computer to generate a new electronic nautical chart, and lay the next sand quilt bag body under the guidance of GPS, and so on until all the tasks of the sand quilt are completed; (2) Sand bag filling on land: Bag body processing: The bagged sand bag bodies (350 g / ㎡ woven non-woven composite geotextile) of this project are all processed in a specialized geotextile factory according to the designed dimensions in advance; Bag body transportation: The geotextile bag bodies of this project are transported to the construction site by water + land transportation, and randomly inspected together with the supervision engineer. The materials that do not meet the requirements are returned; Bag body laying: Before laying the bag body, understand the terrain of the geotextile bag body to be laid and carry out manual laying according to the design drawings. The geotextile bag body is laid according to the positioning and marked and fixed with a benchmark; Sand blowing ship positioning: According to the construction progress requirements, the sand blowing ship reasonably arranges the cofferdam construction plan, accurately positions according to the plan, erects the mud blowing pipeline and the battery, and waits for the self-propelled mud barge to dock fully loaded; Sand material arrival: The self-propelled hopper barge docks at the grab dredger for dredged soil loading operation. After being fully loaded, it sails to the sand blowing ship. Filling of sand bags: After the self-propelled hopper barge is berthed alongside the sand blowing ship, the sand blowing ship uses a high-pressure water gun to impact the cabin of the hopper barge, and fills the sand into the sand bags through a slurry pump. Filling starts from the cuff. When the filling elevation reaches the design requirement, switch to other cuffs to continue filling until the entire bag body is filled to the design requirement. During the filling process, pay attention to controlling the uniformity and fullness of the sand bags. After several consecutive fillings, when the sand bags are filled to 60% - 80%, stop filling the sand bags.

[0023] Such as Figure 3 And Figure 4 As shown, preferably, in step S3, filling the dredged soil into the cofferdam to form a land reclamation construction platform includes: S301, select a sand suction ship according to construction requirements; S302, lay out sand blowing pipelines, floating pipes on water, shore pipes, sand outlet nozzles and water gates; S303, carry out filling operation: The grab of the grab dredger grabs the dredged soil to be dredged and dumps it into the self-propelled hopper barge, and transports it to the side of the sand blowing ship through the self-propelled hopper barge; the sand blowing ship forms a sand suction device through the sand suction pipe, sand suction head and flushing pipe installed on one side of the ship's side. The sand blowing ship loads a large sand suction pump to suck the sand-water mixture from the sand-water mixture in the sand-carrying ship berthed alongside the ship's side, and then transports it to the sand bags and inside the cofferdam through the sand discharge pipeline on the other side of the sand blowing ship. After the sand-water mixture precipitates in the filling area, the sand remains in the filling area, and the tail water is discharged from the construction area through the water gate.

[0024] Preferably, in step S4, the construction of the wharf pile foundation and the trestle on the land reclamation platform includes cast-in-place pile construction, cast-in-situ cross beam and capping beam construction, prefabrication and installation of precast components, cast-in-situ paving layer construction and anti-corrosion construction.

[0025] Preferably, in step S5, the land reclamation and foundation treatment adopt the precipitation dynamic compaction process, including driving the dewatering pipes to lower the groundwater level, tamping in three passes by point tamping and one pass by full tamping, the tamping energy is 2000 - 2500 kN·m, and the full tamping energy is 800 - 1000 kN·m.

[0026] Preferably, in step S6, the removal of the temporary cofferdam includes: Excavate the riprap at the cofferdam toe and the fill at the cofferdam top, and transport it to the solidified soil production area through a backhoe excavator and a dump truck; use a long-arm excavator to demolish the cofferdam body, recover the sand bags and riprap, and transport them to the solidified soil mixing plant.

[0027] Preferably, in step S7, incorporating the recycled materials into the curing agent to produce solidified soil for land reclamation includes: Before the production of solidified soil, for the soil source with water content exceeding the set threshold, a new type of dehydration material is used to reduce the water content of the solidified soil; Before mixing the solidified soil with qualified water content, pre-treatment is carried out. The dehydrated solidified soil is screened, and after screening, the solidified soil is sent to a conveyor belt and then to a crusher for crushing. The soil blocks are crushed into soil particles with a maximum size not exceeding 15 mm to meet the design particle size requirements of the solidified soil; The crushed soil source enters a compulsory mixer through a conveyor belt and is mixed evenly with the solidifying material in the mixing building according to the mixing ratio list required by the design index, and then transported to the in-situ solidification site for filling. The on-site filling adopts a layered rolling process.

[0028] Furthermore, the backfilling of the solidified soil adopts a layered rolling process. The thickness of each layer of loose laying is 50 cm, and the thickness after rolling is 30 - 35 cm. A roller with a weight of more than 20 T is used for static pressure, weak vibration and strong vibration combined rolling.

[0029] Furthermore, the wharf pile foundation construction in the fourth step includes: burying steel casing on the island building platform, adopting the slurry-supported bored pile construction process, with a pile diameter of Φ800 - 1200 mm, and the overpour height at the pile top is greater than 1 times the pile diameter.

[0030] Furthermore, in the first step, the grab dredger adopts GPS positioning and strip-by-strip and layer-by-layer control. The grab capacity is 8 m³, and the dredged soil is preferentially used for cofferdam filling and raw materials for solidified soil.

[0031] Example Two: In this example, the reclamation sand filling work volume of the "island building" is about 79,000 m³. The dredged soil is used for filling, and the "grab - transport - blow" construction process is adopted, and the filling operation is carried out by waterway transportation + hydraulic transportation method; considering many factors such as the particle size of the reclamation sand material and the draft of the ship, when the blowing distance cannot meet the filling requirements, the method of adding a relay pump is used to extend the blowing distance to meet the filling requirements of the reclamation sand construction of this project. Specifically, it can be determined according to the trial blowing results after the start of construction.

[0032] Furthermore, the selection of the sand blowing ship and the sand suction ship according to the construction requirements includes: 1) Selection of the sand blowing ship: In this project, a 350 m³ / h sand blowing ship is selected. The discharge distance of the mud pump of each sand blowing ship can reach 2000 m, and the discharge distance of double pumps in series operation can reach 4000 m. The sand blowing ship can meet the construction requirements. In the case of short blowing distance, the sand blowing ship can adopt single pump operation. In this way, the other mud pump can be properly maintained, which can fully improve the utilization rate of the ship and is relatively beneficial to accelerating the construction progress. The sand blowing ship sucks sand from the barge cabin for transportation, and the sand blowing and discharging concentration is high, generally 20 - 25%. Compared with the filling area, the drainage volume is small, reducing the flow rate of the drainage system. The sand blowing ship is anchored and fixed, with strong wind resistance and small occupied water area.

[0033] 2) Selection of sand suction ship: According to the working conditions of this project and the requirements for the sand quality of sand blowing, an 8 m³ grab dredger is used for sand mining. Its advantages are: simple structure, convenient operation and maintenance, low cost, and strong dredging ability and large dredging depth.

[0034] 3) Selection of sand transport ship Considering the water area conditions and sand transport intensity requirements at the construction site, 500 m³ self-propelled hopper barges are equipped, with a length of about 54.10 m, a width of about 10.70 m, and a full-load draft of about 2.8 m. The selection of self-propelled hopper barges has strong mobility and relatively fast ship speed.

[0035] Furthermore, the layout of sand blowing pipelines and water gates includes: 1) The sand blowing pipelines are laid out according to the principles of being straight rather than curved, low rather than high, and short rather than long. In this project, it is planned to lay out 1 main pipeline and several branch pipelines. After the pipelines are connected from the sand suction ship, they are connected to a section of floating pipeline, and then connected to the shore pipeline. The connection between the floating pipeline on the water and the shore pipeline is through the land-water pipe support head set on the newly built dike, and a rubber pipe is used for flexible connection, that is, the floating pipeline and the shore pipeline are connected in an arc shape with a rubber pipe. To avoid affecting the construction of the newly built dike, pipelines will be preset on the dike and removed after the filling is completed; 2) Layout of floating pipelines on the water: The floating pipeline on the water is affected by factors such as water flow, wind and waves, and the impact force during sand filling construction. Therefore, the clamping between pipe sections must be very firm and reliable. The pipeline layout should be curved in an approximate streamline shape, as straight as possible, and no dead bends should be formed. The floating pipeline should still be above the water surface under heavy load for maintenance. During construction, it is fixed with floating pipeline anchors at certain intervals. The throwing of pipeline anchors should be determined according to the water flow and tide. In this sea area affected by the tide, they must be thrown on both sides in the direction of flood and ebb currents; 3) Layout of shore pipelines: Set land-water pipe support heads on the dike, that is, use rubber pipes for flexible connection, and start from the land-water pipe support heads to connect the shore pipelines into the filling area. When laying out the pipelines, in addition to considering the designed filling elevation, factors such as settlement (including foundation settlement in the site and consolidation settlement of the sand filling itself) and filling over-height should also be considered; to obtain better flatness in the filling area, in addition to the main pipelines, branch pipelines should also be laid out. The layout of the pipelines mainly considers the pipeline spacing, that is, the spacing between the pipe orifices, and the size of the pipe orifice spacing is related to factors such as the mud pump power of the sand suction ship, the topography of the filling area, and the filling soil quality. The pipeline layout should also try to avoid passing through obstacles, but try to avoid overly sharp bends in the pipelines.

[0036] 4) Sand outlet nozzle: According to the spacing of each branch pipeline, the direction of the nozzle can be continuously adjusted during the sand blowing process, so that the sand blowing can flow to the farthest distance on both sides of the shore pipeline, reducing the number of branch pipeline layouts and shortening the construction period. However, when filling near a newly built dike, the outlet of the sludge discharge pipe should be at a certain distance from the dike to avoid the direct scouring of the outlet drainage on the dike. The distance between the dike and the sand blowing nozzle varies depending on the soil quality, dike structure, and height, and is generally maintained in the range of 15 - 20m to avoid direct water flow scouring.

[0037] (3) Water gate layout: 1) The tail water of the filling is discharged from the filling area through the water gates buried on the dike. A total of 2 groups of drainage outlets are set, as shown in the figure; 2) Each group of drainage outlet gates includes: 1 steel water tank gate, 2 spliced drainage steel pipes, and several steel pipe rubber joints. The steel water tank is made of a special prefabricated box-shaped steel structure of the Ministry of Transport's waterway department. The drainage pipe is made of Φ800mm steel pipe with a wall thickness of 10mm; the drainage steel pipe is 8m - 10m long for each section, and a flexible single-sphere rubber joint is set to connect the steel pipes; 3) When burying the drainage pipe, the influence of uneven settlement of the dike body needs to be considered to prevent the fracture and leakage of the steel pipe lap joint due to excessive differential settlement; 4) When burying the drainage pipe, the slope requirement must be met to ensure the smooth drainage of the drainage pipe.

Claims

1. A construction method for repeatedly utilizing dredged soil waste, characterized in that: The following steps are involved: S1, dredging the harbor in sections and layers by grab boats, transporting the dredged soil to self-propelled mud barges and transporting them to the cofferdam construction area; S2, using dredged soil to fill the bagged sand cofferdam to form a temporary cofferdam structure; S3, blowing dredged soil into the cofferdam to form an island construction platform; S4, construction of pier pile foundation and trestle on the island building platform; S5, synchronously implement the foundation treatment and backfill construction of land roads and storage yards; S6, dismantle the temporary cofferdam and recycle the bagged sand and blown fill soil of the cofferdam; S7, mixing the recycled material with a curing agent to produce cured soil for land backfill.

2. A construction method for multiple utilization of dredged soil waste according to claim 1, characterized in that: In step S2, using dredged soil to carry out bagged sand cofferdam filling includes: S201, geotextile processing, sewing and transportation: geotextile processing and sewing are completed at the geotextile processing site, and then shipped to the construction ship through the material shipping terminal; S202, bagged sand construction: When laying underwater, the construction technology of bagged sandbags pulling and filling is adopted. When the sandbags are exposed to the water surface, the bag bodies are manually laid on land combined with the sand blowing ship filling technology.

3. A construction method for multiple utilization of dredged soil waste according to claim 2, characterized in that: In step S202, the specific method of the bagged sand bag pulling and filling construction process is: (1) Bag filling construction: The filling bags are designed in layers according to the design structure size, requirements and equipment construction capacity, and processed into rectangular shapes. The cross-sectional width is based on the cross-sectional width of the sandbag, and the axis length is based on the design drawings. The bag body is manufactured and processed in the geotextile processing plant. (2) Positioning of the tugboat: Use highly maneuverable engineering vessels for pulling boats; The towing boat is stationed at a horizontal distance of 20m from the outer edge of the bag body for each planned filling construction; The towing boat is driven to the designated area, accurately positioned by RTK, and an anchor-throwing boat is used to throw two figure-eight anchor cables at the front and rear to secure the boat. (3) Filling the bag and stretching the fabric: The processed geotextile filling bag is transported by a transport ship to a pulling ship; Each towing boat is connected to the two corner slipknots at one end of the bag with two nylon ropes of sufficient pulling force, and the other end of the nylon rope is fixed on the winch of the towing boat; when the bag is laid and positioned, the adjacent bags on the same layer are overlapped by 2m; The opposite pulling boat starts the winch to pull the bag to the surface and gradually unfold it; the bag is moved to the pre-sinking position by tightening the nylon rope of the winches of the two boats, and the four corners are accurately checked and verified by RTK, and then the nylon rope is tightened to fix the bag; After the bag is positioned, buoys are tied to the four corners of the bag in advance to facilitate the inspection of its position after filling and sinking.

4. A construction method for multiple utilization of dredged soil waste according to claim 2, characterized in that: In step S202, the onshore manual bag laying combined with the sand blowing ship filling process includes a filling operation, and the specific method is: The sand-blowing ship fills the sea sand into the filling bags through the delivery pipeline laid out at sea; The sand conveying pipe is made of high-strength plastic pipe and rubber hose with a diameter of 400mm. The high-strength plastic pipe is laid on site in the form of a submerged pipe and then floats to the surface. The main pipe is then divided into multiple branches through a diverter valve. The diverter valve is set on the floating boat. The branch pipe is connected to the cuff of the bag body with a 6-inch acrylic hose, and then extends into the cuff, extends to the bag body and is tied firmly. After the branch pipe is connected to the cuff, the high-pressure water gun on the sand-blowing ship is turned on to flush and stir the sand in the sand-carrying ship's cabin. The hydraulic flushing and excavation unit is used to suck sand from the sand-carrying ship's cabin, and the sand is transported to the filling position through the conveying pipeline. After being diverted by the diverter, the sand bag is filled. When filling, fill the four corners of the bag first, and loosen the nylon rope while filling to slowly sink the filling bag; After the bag is filled and sunk into place, finally untie the nylon rope and the anchor rope; during the filling process, periodically measure the water depth at the bag position, calculate the height of the sand accumulation in the bag, and replace the filling cuff position in time; By constantly adjusting the sand filling port, the sand in the bag is filled evenly and fully, ensuring the filling is smooth, and speeding up the drainage and consolidation of the bag; when the entire sand bag reaches the slurry screen stage, appropriately reduce the sand bag filling equipment or suspend filling to prevent the bag from bursting, leaving a certain consolidation and dehydration time; If the ideal height cannot be reached in one filling process, the sand bags shall be filled for a second or multiple times after they are slightly solidified. If damage is found during the construction process, the filling shall be stopped, and the bags shall be rearranged and filled again. Determine the construction position of the next sand blanket bag according to the actual coordinate position of the previous sand blanket, input it into the computer to generate a new electronic nautical chart, and lay the next sand blanket bag under the guidance of GPS, and so on until the entire sand blanket task is completed.

5. A construction method for multiple utilization of dredged soil waste according to claim 4, characterized in that: In step S202, the onshore manual laying of bags combined with the sand blowing ship filling process includes onshore sand bag filling, and the specific method is: Bag processing: The bag is processed in the geotextile processing plant according to the design requirements; Bag transportation: transport to the construction site by water and land transportation, and remove materials that do not meet the requirements; Bag laying: Before laying the bag, understand the terrain where the geotextile bag is to be laid, and lay it manually according to the design drawings; the geotextile bag is laid according to the positioning, and marked and fixed with a benchmark; Positioning of sand-blowing ship: According to the construction progress requirements, the sand-blowing ship reasonably arranges the cofferdam construction plan, accurately positions according to the plan, sets up mud-blowing pipelines and turrets, and waits for the self-propelled mud barge to dock fully loaded; Sand material entering the site: the self-propelled mud barge docks at the grab ship to load the dredged soil. After being fully loaded, the self-blowing sand ship sails; Bag sand filling: After the self-propelled mud barge docks with the sand blowing ship, the sand blowing ship uses a high-pressure water gun to impact the mud barge cabin, and fills the sand into the sand bags through a mud pump, starting from the cuffs. When the filling elevation reaches the design requirements, switch to other cuffs to continue filling until the entire bag is filled to the design requirements; fill the sand bags multiple times continuously during the filling process, and stop filling the sand bags when they are filled to 60% to 80%.

6. The construction method for multiple utilization of dredged soil waste according to claim 1, characterized in that: In step S3, filling dredged soil into the cofferdam to form an island construction platform includes: S301, select and suck sand boat according to construction requirements; S302, laying out sand blowing pipelines, floating pipes, shore pipes, sand outlet nozzles and water gates; S303, perform blowing and filling operation: The grab bucket of the grab ship grabs the soil to be dredged and dumps it into the self-propelled mud barge, which is then transported to the sand-blowing ship via the self-propelled mud barge. The sand-blowing ship is equipped with a sand suction device consisting of a sand suction pipe, a sand suction head and a water flushing pipe installed on one side of the ship's side. The sand-blowing ship is equipped with a large sand suction pump to suck the sand-water mixture from the sand-carrying ship moored beside the side, and then transports it to the sand bags and cofferdams through the sand discharge pipeline on the other side of the sand-blowing ship. After the sand-water mixture is precipitated in the filling area, the sand remains in the filling area, and the tail water is discharged from the construction area through the sluice gate.

7. The construction method for multiple utilization of dredged soil waste according to claim 1, characterized in that: In step S4, the wharf pile foundation and trestle construction are carried out on the island building platform, including cast-in-place pile construction, cast-in-place cross beam and cap beam construction, prefabrication and installation of prefabricated components, cast-in-place pavement construction and anti-corrosion construction.

8. The construction method for multiple utilization of dredged soil waste according to claim 1, characterized in that: In step S5, the land backfill and foundation treatment adopts the precipitation compaction technology, including inserting precipitation pipes to lower the groundwater level, three times of spot compaction and one time of full compaction, the compaction energy is 2000-2500kN·m, and the full compaction energy is 800-1000kN·m.

9. The construction method for multiple utilization of dredged soil waste according to claim 1, characterized in that: In step S6, the temporary cofferdam removal includes: The rocks at the foot of the dam and the filling soil on the top of the dam are removed and transported to the solidified soil production area by a backhoe excavator and a dump truck; the long-arm excavator dismantles the dam body, recovers the sand bags and rocks, and transports them to the solidified soil mixing site.

10. The construction method for multiple utilization of dredged soil waste according to claim 1, characterized in that: In step S7, the recycled material is mixed with a curing agent to produce solidified soil for land backfilling, including: Before the production of solidified soil, for soil sources whose moisture content exceeds the set threshold, new dehydration materials are used to reduce the moisture content of the solidified soil; Pre-treat the solidified soil with qualified moisture content before mixing, screen the dehydrated solidified soil, and send the screened solidified soil to the conveyor belt to the crusher for crushing, and crush the soil blocks into soil particles with a maximum size of no more than 15mm to meet the designed particle size requirements of the solidified soil; The crushed soil source then enters the forced mixer and solidifying material in the mixing plant through a conveyor belt and is mixed evenly according to the mix ratio required by the design indicators. It is then transported to the on-site solidification site for filling. The on-site filling adopts a layered compaction process.

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