CN117587742A - Method for quickly dredging large lake with thicker silt covering layer - Google Patents

Abstract

The method for rapidly dredging the large lake with thicker silt covering layer comprises the following steps: 1. preparing before construction, familiarizing with construction drawings, programming schemes and intersecting materials; 2. measuring and paying off; 3. digging a drainage ditch, utilizing the natural water level difference between the river and the lake to excavate the drainage ditch, discharging accumulated water in the lake, and pumping the residual water which cannot be discharged by using a water pump to drain; 4. excavating a channel, namely excavating to a powdery clay layer by adopting a transverse and longitudinal crossed channel or a fishbone-shaped channel; 5. carrying out sludge outward, using a clay layer as a construction channel, and carrying out sludge and powdery clay by using a residue-soil vehicle; 6. slope protection; 7. pushing and filling sludge on two sides, pushing the sludge subjected to natural dehydration to an over-excavation channel part and a beach position by adopting a bulldozer according to the actual condition of the sludge on site after the channel is constructed, and backfilling to a designed elevation position; 8. excavating a next channel; the invention solves the problems of more land, serious pollution and slow construction progress of the traditional dredging method and realizes the dry method in-situ rapid dredging.

Description

Method for quickly dredging large lake with thicker silt covering layer

Technical Field

The invention relates to the technical field of dredging, in particular to a rapid dredging method for a large lake with a thicker silt covering layer.

Background

The water area of China is wide, various river and lake are widely distributed, and in actual development, how to effectively implement dredging treatment operation of the river and the lake and reasonably improve the resource management quality of the related water area becomes a main problem in the current river and lake resource management development.

The techniques commonly used at present are ecological management techniques, physical excavation techniques, chemical methods and drainage consolidation techniques. The ecological treatment technology is mainly implemented by cleaning the cementing materials on the surface layer of the silt and suspending pollutants, and in the treatment process, the phenomenon of secondary pollution caused by muddy silt due to overlarge mechanical vibration force is easy to occur; the physical dredging technology is a common dredging technology, and sludge cleaning operation in river and lake areas is mainly carried out through dredging vessels and dredger, the water content of the sludge cleaned by the method is high, dredging is not thorough, the natural dewatering time of the sludge is long, a large number of slag fields are required to be collected, and the difficulty and the cost of subsequent farmland reconstruction are high; the chemical method mainly carries out rapid solidification of the silt by a hydrolysis method, the dosage is difficult to control in the implementation process, aquatic death is easy to cause, economic loss is caused, and the recovery cost of the later cultivated land is high; the drainage consolidation technology is mainly used for cleaning river and lake silt through cofferdam technology, silt surface loading technology and excavation and clearing technology, and analysis is carried out from the current application state, and the technology has the characteristics of complex construction procedure and high manufacturing cost in practical application and is easy to cause secondary pollution.

Based on the problems, a dredging method with small secondary pollution, few land symptoms, simple construction procedure and low cost is urgent, the country and the place are important, the national institute of research and development provides that the lake treatment needs to be suitable for the lake, the short-term effect cannot be pursued uniformly, and some technical schemes are also emerging in each project of each lake at present.

For example, CN201710345863 discloses a method and system for environmental dredging of large reservoirs and lakes, the method for environmental dredging comprises: on the water surface of lakes and reservoirs subjected to sludge cleaning, a module buoyancy tank, a driving buoyancy tank, a domestic water buoyancy tank, a sewage buoyancy tank and the like are assembled to form a floating platform; the floating platform is provided with a sludge sucking device, a sand and garbage separating device, a dewatering device, a drying device, a carbonization device, a sewage purifying device, a diesel generator, a diesel storage tank, a steam boiler, a fuel warehouse, an anchor windlass, living facilities and other devices; carrying out carbonization after pretreatment on the sludge pumped by the sludge pumping device, thereby realizing on-site sludge cleaning on the water surface; the method has large engineering quantity of the water construction project, and is also a mode of pumping the silt by adopting a silt sucking pump, so that the silt is easy to be back-silted.

For example, CN103215931a discloses a method for dredging and draining a lake wetland based on assembly of components, namely a dredging and draining method for dredging and draining a lake by assembling a detachable temporary lake river with a water outlet in sealing butt joint with a lake water outlet in the lake wetland by using components, using equipment capable of flushing and disturbing lake sediment near the water inlet of the lake river to lift the sediment and pollutants, and enabling the sediment and pollutants to flow into the lake river together with water, and finally discharging the sediment and the pollutants out of the lake; the method has the advantages of large equipment investment, large engineering quantity, long period and slow effect, and is not suitable for lakes with thicker silt layers.

But the project has the advantages of large dredging amount, large water content and large depth of sludge (the average depth of the sludge is 4-5 meters, the average dredging depth is 1-2 meters), the water dredger and the wetland excavator cannot walk on the sludge, a large amount of sludge is stored without places, the outward transportation cost is high, a large amount of farmlands and pits are occupied by the traditional dredging mode, the outflow of sludge substances is easy to cause, and a series of problems such as influence on the surrounding environment and water and soil conservation are caused. Meanwhile, project embankment reinforcement is large in engineering quantity, no filler source exists, outsourcing earthwork is high in cost and the like.

Based on the above problems, the project is to be adopted: channel dry dredging, removing ponding in the lake, excavating a longitudinal channel to a powdery clay layer along a deep water area in the lake, paving a slag stone on the powdery clay layer, using a channel bottom as a sludge outward transportation channel, solving the problems of sludge transportation and the like, excavating drainage ditches and drainage ditches at the positions of an upper opening and a bottom opening of the channel, removing the problems of natural dehydration and draining of ponding and sludge in the construction process, and the like, wherein the actual dredging amount and the total dredging amount are balanced through calculation of excavation sections, the powdery clay is used for backfilling embankments in the channel excavation process, and the sludge is used for filling habitat islands and waste slag fields. Backfilling the residual dredging amount of sludge to a channel by using a bulldozer and a digger after the sludge is naturally dehydrated, and leveling; the technology is applied to the project, can greatly reduce the construction cost, relieve the environmental protection effect of the water, reduce the land work load and improve the social and economic benefits.

Disclosure of Invention

The invention aims to solve the technical problems of more land, serious pollution, slow construction progress, difficult later ecological restoration and high cost of the traditional dredging methods of ship dredging, dredger pump, cutter suction ship and the like.

In order to solve the technical problems, the invention adopts the following technical scheme: the method for rapidly dredging the large lake with thicker silt covering layer comprises the following steps:

step1: preparing before construction, familiarizing with construction drawings, programming schemes and intersecting materials;

step2: measuring and paying off;

step3: digging a drainage ditch, utilizing the natural water level difference between the river and the lake to drain the accumulated water in the lake, arranging a drainage ditch and a water collecting pit in the lake according to the drainage amount, and pumping out and draining the water by using a water pump;

step4: the channel is excavated, the channel is divided into a main channel and a north-south channel, and a transverse cross channel or a longitudinal cross channel or a fishbone-shaped channel is adopted for excavating to a powdery clay layer;

step5: carrying out sludge outward, using a powdery clay layer as a construction channel, and carrying out sludge and powdery clay outward by using a residue-soil vehicle;

step6: slope protection;

step7: pushing and filling sludge on two sides, pushing the naturally dehydrated sludge layer to the over-excavated channel part and the beach area by adopting a bulldozer according to the actual condition of the sludge on site after the channel is constructed, and backfilling to the designed elevation position;

step8: and excavating the next channel.

In a preferred scheme, the specific steps of the step2 are as follows: before construction, calculating the section and the folding point position of a channel, drawing a plane position diagram according to the channel layout diagram, performing site lofting after rechecking, ensuring the channel deviation value of +/-50 mm according to the precision requirement, positioning an axis by using a GPS, performing engineering measurement pay-off according to the planned channel layout coordinates, determining a pile position center line and an excavation boundary line, and marking a dust scattering line.

In a preferred scheme, the specific steps of the step3 are as follows: according to the on-site investigation condition, a drainage ditch is annularly arranged at a position 3 m-4 m away from a channel, the longitudinal gradient is 2 per mill, lake water is discharged along the drainage ditch, a water collecting pit is arranged along the drainage ditch according to actual drainage amount, water is pumped in a concentrated mode by a water pump, and the fact that the external water source of the channel does not enter the channel to influence construction is guaranteed.

In a preferred scheme, the specific steps of the step4 are as follows:

step4.1: according to construction lofting and bottom crossing, make the lofting on the spot, draw the excavation line of side slope on the foundation ditch with lime, excavate north-south direction channel in the better position of soil property according to the data of land survey, set up 1:10 side slopes to an excavation channel;

step4.2: the method comprises the steps of simultaneously excavating the channel from the channel to the east and west sides longitudinally, continuously constructing the excavation operation, synchronously operating 2 excavating machines in the same direction, configuring 2 residue-soil trucks for each excavating machine, excavating a silt layer to a ground investigation depth powder clay layer at a time, wherein the distance between the front and rear of the two excavating machines is not less than 20 m;

step4.3: the silt and the soil are dug and transported respectively and are not mixed, the silt at the upper part is transported to a lake center island, the good soil at the shallow part of the silt is transported to a backfill dike top roadbed, and the rest square quantity is transported to a spoil field along the outer dike;

step4.4: 2% transverse slopes are arranged along the central line of the channel substrate to two sides, the longitudinal slope is 2 per mill, and slag stones are paved at the bottom of the channel, and the thickness is 50cm;

step4.5: the sectional dimension of the channel, the slope ratio and the like can be properly adjusted according to the actual excavation condition of the site, and sand bags or fir piles are arranged at the slope angle positions to support the slope, so that the slope collapse caused by construction vibration is prevented, and the silt excavation operation industry is prevented from being influenced.

In a preferred embodiment, the specific steps of the step6 are as follows: the channel side slope adopts soil bags or fir piles for protection according to the actual deformation of the side slope.

In a preferred scheme, the concrete method for protecting the soil bag comprises the following steps: the soil bags are manually bagged to 70 percent of the capacity by adopting a channel substrate to excavate side ditch earthwork, the bag openings are fastened, three layers are stacked along the position of the slope toe, and the soil bags are stacked horizontally and vertically and are connected up and down in a staggered manner, so that a through seam is not formed.

In a preferred scheme, the concrete method for protecting the fir stumps comprises the following steps:

step6.1: the fir tree piles are loaded by adopting a land dump truck, the piles are manually distributed along the slope toe on site, and the piles are manually straightened and positioned and pressed by a shovel bucket of a digging machine;

step6.2: the upper part of the fir tree pile is subjected to three-way anti-corrosion treatment by asphalt, before piling, the pile top is cut off and sawed to be smooth, the pile body is protected, collision flaws affecting functions cannot be generated, and the pile head part is fastened by iron wires;

step6.3: the excavator is a hydraulic excavator, when piling, two persons hold piles in place, the bucket is reversely buckled on the pile top, the tree piles are pressed into a foundation to a certain depth, after the fir tree piles are self-stabilized, workers are removed, and the excavator presses the fir tree piles to a designed elevation.

The method for rapidly dredging the large lake with thicker silt covering layer has the following beneficial effects:

1. the invention utilizes the difference of high and low water level to drain and pump water in the original lake, thereby reducing the occupation of surrounding land;

2. according to the invention, the fishbone channel is excavated to the hard stratum after drainage is adopted, so that an access channel is provided for construction equipment, and construction and transportation are convenient;

3. according to the invention, the fishbone channel is adopted, meanwhile, the drainage ditch is arranged around the channel, and the water collecting pit is arranged at the bottom, so that the water in the silt layer can be drained as soon as possible, and the construction is not influenced;

4. the fishbone channel is arranged, so that the silt layers on two sides can be naturally dehydrated and dried, the nearby backfilling of the super-excavated part in the later period is facilitated, the cost input of outsourcing filling is reduced, and meanwhile, the construction efficiency is improved;

5. according to the invention, the side slope protection adopts the protection of the soil bags and the fir piles, so that the earthwork in the lake is fully utilized in situ, and the recovery of the later ecological environment is facilitated;

6. according to the invention, the slag stone is paved at the bottom of the channel, so that the channel is further reinforced, the in-out and construction of construction equipment are facilitated, the slag stone can be repeatedly used in construction, and the construction cost is further saved;

7. the invention adopts the original lake site drainage and channel construction, the sludge layer around the drainage and air-drying channel is used as the super-excavation backfill layer and the dam reinforcement layer, thereby reducing the land reclamation workload, protecting the ecological environment, accelerating the overall construction progress of the engineering, having simple construction procedure, strong operability, wide applicability and high popularization value;

8. the dry method adopted by the invention has the advantages of deep dredging, increasing the storage capacity of the original lake, relieving the bitterness of water logging and flood fighting puzzling for a plurality of years in the local area, laying a solid foundation for the later local flood fighting work, benefiting the country and the people, and having good economic and social benefits.

Drawings

The invention is further illustrated by the following examples in conjunction with the accompanying drawings:

FIG. 1 is a schematic view of a channel arrangement of the present invention;

FIG. 2 is a schematic view of a dredging section construction section of the present invention;

FIG. 3 is a schematic cross-sectional view of a main channel of the present invention;

FIG. 4 is a schematic cross-sectional view of a north-south aisle of the present invention;

in the figure: drainage ditch 1, water collecting pit 2, main channel 3, north-south channel 4, silty clay layer 5, silt layer 6.

Detailed Description

As shown in fig. 1 to 4, the method for rapid dredging of large lakes with thicker silt covering layers comprises the following steps:

step1: preparing before construction, familiarizing with construction drawings, programming schemes and intersecting materials;

step2: measuring and paying off;

step3: digging a drainage ditch 1, utilizing the natural water level difference between a river and a lake to excavate the drainage ditch 1, draining accumulated water in the lake, and draining residual lake water which cannot be drained, arranging the drainage ditch 1 and a water collecting pit 2 in the lake according to drainage amount, and pumping out and draining by using a water pump;

step4: the channel is excavated, the channel is divided into a main channel 3 and a north-south channel 4, and transverse and longitudinal crossed channels or fishbone-shaped channels are adopted for excavating to a powdery clay layer 5;

step5: carrying out sludge outward, using a powdery clay layer 5 as a construction channel, and carrying out sludge and powdery clay outward by using a residue-soil vehicle;

step6: slope protection;

step7: pushing and filling sludge on two sides, pushing a naturally dehydrated sludge layer 6 to an over-excavation channel part and a beach area part by adopting a bulldozer according to the actual condition of the sludge on site after the channel is constructed, and backfilling to a designed elevation position;

step8: and excavating the next channel.

In this embodiment, the specific steps of the step2 are as follows: before construction, calculating the section and the folding point position of a channel, drawing a plane position diagram according to the channel layout diagram, performing site lofting after rechecking, ensuring the channel deviation value of +/-50 mm according to the precision requirement, positioning an axis by using a GPS, performing engineering measurement pay-off according to the planned channel layout coordinates, determining a pile position center line and an excavation boundary line, and marking a dust scattering line.

The specific steps of the step3 are as follows: according to the on-site investigation condition, a drainage ditch 1 is annularly arranged at a position 3 m-4 m away from a channel, the longitudinal gradient is 2 per mill, lake water is discharged along the drainage ditch 1, a water collecting pit 2 is arranged along the direction of the drainage ditch 1 according to actual drainage amount, water is pumped in a concentrated manner by a water pump, and the condition that the external water source of the channel does not enter the channel to influence construction is ensured.

The specific steps of the step4 are as follows:

step4.1: according to construction lofting and bottom crossing, make the lofting on the spot, draw the excavation line of side slope on the foundation ditch with lime, excavate north-south direction channel in the better position of soil property according to the data of land survey, set up 1:10 side slopes to an excavation channel;

step4.2: the method comprises the steps of simultaneously excavating the sidewalk to the channel position, longitudinally and simultaneously excavating to the east and west sides, continuously constructing the excavation operation, synchronously operating 2 excavating machines in the same direction, configuring 2 residue-soil trucks for each excavating machine, excavating a silt layer 6 to a ground investigation depth powder clay layer 5 at a distance of not less than 20 m from the front to the back of the two excavating machines;

step4.3: the silt and the soil are dug and transported respectively and are not mixed, the silt at the upper part is transported to a lake center island, the good soil at the shallow part of the silt is transported to a backfill dike top roadbed, and the rest square quantity is transported to a spoil field along the outer dike;

step4.4: 2% transverse slopes are arranged along the central line of the channel substrate to two sides, the longitudinal slope is 2 per mill, and slag stones are paved at the bottom of the channel, and the thickness is 50cm;

step4.5: the sectional dimension of the channel, the slope ratio and the like can be properly adjusted according to the actual excavation condition of the site, and sand bags or fir piles are arranged at the slope angle positions to support the slope, so that the slope collapse caused by construction vibration is prevented, and the silt excavation operation industry is prevented from being influenced.

The concrete step of the step6 is that the channel side slope adopts soil bags or fir tree piles for protection according to the actual deformation of the side slope:

the concrete method for protecting the soil bag comprises the following steps: the soil bags are manually bagged to 70 percent of the capacity by adopting a channel substrate to excavate side ditch earthwork, the bag openings are fastened, three layers are stacked along the position of the slope toe, and the soil bags are stacked horizontally and vertically and are connected up and down in a staggered manner, so that a through seam is not formed.

The concrete method for protecting the fir stumps comprises the following steps:

step6.1: the fir tree piles are loaded by adopting a land dump truck, the piles are manually distributed along the slope toe on site, and the piles are manually straightened and positioned and pressed by a shovel bucket of a digging machine;

step6.2: the upper part of the fir tree pile is subjected to three-way anti-corrosion treatment by asphalt, before piling, the pile top is cut off and sawed to be smooth, the pile body is protected, collision flaws affecting functions cannot be generated, and the pile head part is fastened by iron wires;

step6.3: the excavator is a hydraulic excavator, when piling, two persons hold piles in place, the bucket is reversely buckled on the pile top, the tree piles are pressed into a foundation to a certain depth, after the fir tree piles are self-stabilized, workers are removed, and the excavator presses the fir tree piles to a designed elevation.

By adopting the dredging method, dredging work in the project lake is safely and rapidly completed, the problems of incomplete dredging, easy dredging and the like of the traditional dredging method are avoided, the land reclamation workload is reduced, the overall construction progress of the project is quickened, meanwhile, an earthwork source is provided for the embankment reinforcement project, meanwhile, the embankment top road, greening and landscape project are built, the project is rapidly completed, a solid foundation is laid for local flood control and drainage work, the country is benefited, the ecological environment is protected, the construction program is simple, the operability is strong, the applicability is wide, the popularization value is high, and good economic and social benefits are achieved.

Claims (7)

1. A method for rapid dredging of a large lake with a thicker silt cover layer, which is characterized by comprising the following steps:

step1: preparing before construction, familiarizing with construction drawings, programming schemes and intersecting materials;

step2: measuring and paying off;

step3: digging a drainage ditch (1), digging the drainage ditch (1) by utilizing the natural water level difference between a river and the interior of a lake, discharging accumulated water in the lake, and arranging the drainage ditch (1) and a water collecting pit (2) in the lake according to the drainage amount, and pumping out and draining by using a water pump;

step4: the channel is excavated, the channel is divided into a main channel (3) and a north-south channel (4), and transverse and longitudinal crossed channels or fishbone-shaped channels are adopted to excavate to a powdery clay layer (5);

step5: carrying out sludge outward, using a powdery clay layer (5) as a construction channel, and carrying out sludge and powdery clay outward by using a residue-soil vehicle;

step6: slope protection;

step7: pushing and filling sludge on two sides, pushing a naturally dehydrated sludge layer (6) to an over-excavation channel part and a beach area part by adopting a bulldozer according to the actual condition of the sludge on site after the channel is constructed, and backfilling to a designed elevation position;

step8: and excavating the next channel.

2. The method for rapid dredging of large lakes with thicker silt cover layer according to claim 1, wherein the specific steps of the step2 are as follows: before construction, calculating the section and the folding point position of a channel, drawing a plane position diagram according to the channel layout diagram, performing site lofting after rechecking, ensuring the channel deviation value of +/-50 mm according to the precision requirement, positioning an axis by using a GPS, performing engineering measurement pay-off according to the planned channel layout coordinates, determining a pile position center line and an excavation boundary line, and marking a dust scattering line.

3. The method for rapid dredging of large lakes with thicker silt cover layer according to claim 1, wherein the specific steps of the step3 are as follows: according to the on-site investigation condition, a drainage ditch (1) is annularly arranged at a position 3 m-4 m away from a channel, the longitudinal gradient is 2 per mill, lake water is discharged along the drainage ditch (1), a water collecting pit (2) is arranged along the drainage ditch (1) according to actual drainage amount, water is pumped intensively by a water pump, and the condition that the external water source of the channel does not enter the channel to influence construction is ensured.

4. The method for rapid dredging of large lakes with thicker silt cover layer according to claim 1, wherein the specific steps of the step4 are as follows:

step4.1: according to construction lofting and bottom crossing, make the lofting on the spot, draw the excavation line of side slope on the foundation ditch with lime, excavate north-south direction channel in the better position of soil property according to the data of land survey, set up 1:10 side slopes to an excavation channel;

step4.2: the method comprises the steps of simultaneously excavating the channels from the channels to the positions of the channels longitudinally to the east and west sides, continuously constructing the excavation operation, synchronously operating 2 excavating machines in the same direction, configuring 2 residue-soil trucks for each excavating machine, excavating a silt layer (6) to a ground investigation depth powdery clay layer (5) at a distance of not less than 20 m from the front to the back of the two excavating machines;

step4.3: the silt and the soil are dug and transported respectively and are not mixed, the silt at the upper part is transported to a lake center island, the good soil at the shallow part of the silt is transported to a backfill dike top roadbed, and the rest square quantity is transported to a spoil field along the outer dike;

step4.4: 2% transverse slopes are arranged along the central line of the channel substrate to two sides, the longitudinal slope is 2 per mill, and slag stones are paved at the bottom of the channel, and the thickness is 50cm;

step4.5: the sectional dimension of the channel, the slope ratio and the like can be properly adjusted according to the actual excavation condition of the site, and sand bags or fir piles are arranged at the slope angle positions to support the slope, so that the slope collapse caused by construction vibration is prevented, and the silt excavation operation industry is prevented from being influenced.

5. The method for rapid dredging of large lakes with thicker silt cover layer according to claim 1, wherein the specific steps of the step6 are as follows: the channel side slope adopts soil bags or fir piles for protection according to the actual deformation of the side slope.

6. The method for rapid dredging in large lakes with thicker silt cover layer according to claim 5, wherein the concrete method for protecting the soil bags is as follows: the soil bags are manually bagged to 70 percent of the capacity by adopting a channel substrate to excavate side ditch earthwork, the bag openings are fastened, three layers are stacked along the position of the slope toe, and the soil bags are stacked horizontally and vertically and are connected up and down in a staggered manner, so that a through seam is not formed.

7. The method for rapid dredging in large lakes with thicker silt cover layer according to claim 5, wherein the concrete method for protecting fir tree piles is as follows:

step6.1: the fir tree piles are loaded by adopting a land dump truck, the piles are manually distributed along the slope toe on site, and the piles are manually straightened and positioned and pressed by a shovel bucket of a digging machine;

step6.2: the upper part of the fir tree pile is subjected to three-way anti-corrosion treatment by asphalt, before piling, the pile top is cut off and sawed to be smooth, the pile body is protected, collision flaws affecting functions cannot be generated, and the pile head part is fastened by iron wires;

step6.3: the excavator is a hydraulic excavator, when piling, two persons hold piles in place, the bucket is reversely buckled on the pile top, the tree piles are pressed into a foundation to a certain depth, after the fir tree piles are self-stabilized, workers are removed, and the excavator presses the fir tree piles to a designed elevation.