Rapid filling method suitable for land and water construction of cofferdam with cohesive soil at soil sampling point

Abstract

The invention relates to a water and land construction rapid filling method suitable for a cofferdam with cohesive soil at a soil taking point. The water and land construction rapid filling method comprises the following steps of A, underwater throwing filling, B, overwater turning filling and C, land filling of a dam core. Water throwing and land throwing are combined, cofferdam forming is accelerated, inland river conventional equipment is adopted for overwater construction, construction organization is facilitated, adopted dredgers are backhoe dredgers and grab dredgers which are commonly used for earth cutting in inland rivers, and the ships are shallow in draught, convenient to transport in the inland rivers, free of weather influence, capable of working continuously, capable of saving the construction period, capable of reducing soil disturbance and convenient to throw and fill water. The overall stability of the cofferdam can be improved, earthwork balance is achieved, cost is saved, environment friendliness is achieved, and good social and economic benefits are achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of hydraulic engineering construction, and particularly relates to a cofferdam water-land construction rapid filling method suitable for a clay soil at a soil taking point. BACKGROUND

[0002] The cofferdam is a commonly used temporary retaining structure in the construction of hydraulic engineering, and the fill cofferdam is widely used in China due to its simple structure, easy availability of local materials, and economic and suitable advantages. In the construction of various types of water conservancy hubs, affected by the water level during the flood and dry seasons of rivers, how to quickly fill and form the cofferdam is a key process and construction premise that restricts the construction of a project. For the beach area where the soil taking point is clay soil (such as the beach area), and which is affected by rainfall and cannot be effectively transported by land, it is difficult to construct with land excavation and backfilling equipment, and how to solve the problem of cofferdam filling after water and heightening construction, and how to promote the rapid formation of the cofferdam are real problems faced by the project.

[0003] Patent CN208201895U discloses a shallow water soft foundation ton bag cofferdam, which is composed of clay ton bags, clay cofferdam cores, water-facing slope protection, counter-pressure platforms, and backwater-facing filter layers. The ton bags are stacked at the cofferdam slope foot above the water surface line by 50 cm using a crane during the cofferdam filling construction process, and the cofferdam clay cofferdam core filling is performed after the positioning and hoisting of the clay ton bags are completed. Although this patent uses clay as the cofferdam filling, it is not convenient to fill the bag when the clay soil has a large water content, and the water level difference between the flood season and the dry season is large in the southern weather with much rainfall. The use of land excavation construction equipment is limited, especially for clay soil with a high water content, which is further affected by rainfall, and the softening degree of the soil body is increased. The use of land excavation and land pushing equipment has a large subsidence or submersion risk.

[0004] Patent CN114718096A discloses a clay cofferdam water retaining structure, which mainly uses multiple water retaining plates to form a water retaining cofferdam. The water retaining plates are internally provided with cavities, and the water retaining cofferdam has high stability and can effectively resist the impact force of river water. However, the water retaining plates need to be provided with mutually cooperating clamping blocks and clamping grooves on both sides, and the lower end of the water retaining plate is provided with a fixing mechanism, and the outer side wall is provided with a supporting mechanism. The entire water retaining structure consumes a large amount of materials, and the use cost of the cofferdam as a temporary engineering is high, which is not economical and reasonable.

[0005] The conventional construction method cannot be applied to the large amount of earthwork required by large water conservancy projects, and there is no soil available near the engineering area. The existing soil in the engineering area is clay soil, and the land excavation and backfilling equipment cannot be constructed due to the rainy climate, and the cofferdam filling engineering construction cannot be completed. SUMMARY

[0006] The purpose of the present application is to provide a cofferdam water-land construction rapid filling method suitable for the cofferdam with clay soil at the soil taking point, aiming to solve the problem that the cofferdam cannot be directly constructed with the storage soil due to the lack of qualified soil source around the project, the designated soil taking area is clay soil, there is no road around for passing, and the local area is rainy all year round, and the flood during flood season causes the land excavation and land pushing equipment to have a large subsidence or flooding risk and cannot complete the cofferdam.

[0007] The technical scheme adopted by the present application is: a cofferdam water-land construction rapid filling method suitable for the cofferdam with clay soil at the soil taking point, comprising the following steps: A. underwater throwing filling, using a backhoe dredger to take soil nearby, using an open-body barge to load and transport the soil, and throwing filling to the nearby water surface at the designated position of the cofferdam; B. overwater throwing filling, using the characteristics of the grab dredger that is not affected by rainy weather and can rotate 360 degrees to take soil from one side of the bottom sealing barge, rotate to the other side of the cofferdam to be built to throw soil, until the throwing filling is out of water, solving the problem of difficult throwing filling of the cofferdam in water, and avoiding the secondary water disturbance to the excavated earthwork, reducing the influence on the soil quality parameter index and characteristics; C. land filling of the cofferdam core, after the cofferdam throwing filling is out of water, using land layer-by-layer filling of the purchased mountain skin clay to form an 8m wide cofferdam core, and when layer-by-layer filling, the cofferdam body soft soil layer is compressed and thinned, and the soil body is extruded to form a stable natural gentle slope, forming an effective cofferdam core protection structure, and the cofferdam core is replaced by stable soil, ensuring the stability of the cofferdam structure.

[0008] The further technical scheme of the present application is: the construction method of the step A underwater throwing filling includes pulling soil by the backhoe dredger, measuring and laying out the bottom edge line of the open channel in the diversion channel area, inserting a flagpole as the excavation guide, then using the backhoe dredger to excavate from both ends of the open channel to the middle of the open channel along the excavation line, and excavating layer by layer and strip by strip, the thickness of each layer is ≤2m, the width of each strip is the front working diameter of the shovel when it is submerged in water, and the overlap between strips is ≥1m to avoid missing excavation, and warning floats are arranged around the dredger during construction; the open-body barge cofferdam underwater throwing filling, when throwing filling, the earthwork is loaded and transported by the open-body barge, the open-body barge sails at low speed to the cofferdam water area after loading, and the open-body barge throws mud after rough positioning, the open-body barge cannot exceed the full load water line when loading, the wind speed and water flow should be paid attention to during sailing, the sailing route should be fixed, and good avoidance measures should be taken with other ships, and the water depth of the open-body barge should be measured before throwing filling to avoid grounding.

[0009] The further technical scheme of the present application is that the construction process of the step B water filling includes that the cofferdam is filled under water to the cofferdam body near the water surface, when the water level is shallow and the body barge cannot sail to the cofferdam body, the cofferdam positioning and filling construction is carried out by using the grab dredger, in the construction, first, the grab dredger is positioned in the side of the cofferdam filling position in advance, then the backhoe dredger is used to take the relatively good earth above the water surface from the nearby, the earth is transported to the cofferdam construction area by the bottom barge, the bottom barge is parked outside the grab dredger, then the grab of the dredger is used to take the earth from the bottom barge, and the earth is rotated to the other side of the cofferdam to be filled and added, until the cofferdam cannot be added any more after the filling out of the water surface.

[0010] The further technical scheme of the present application is that the construction method of the step C land filling embankment core includes that the land filling embankment core is filled, after the cofferdam is filled out of the water surface, the land pushing equipment is used to form the 8m wide stable embankment core by 50cm layer by layer spreading the purchased mountain clay, and the cofferdam body is thinned by extruding the soft soil layer, and the stable natural slope is formed by extruding part of the soil, and the embankment core is replaced by the stable earth.

[0011] The further technical scheme of the present application is that the cofferdam is constructed by the purchased mountain clay layer by layer, at the same time, the slope surface on the two sides of the cofferdam is reinforced by excavating the nearby earth, the purchased mountain clay and the nearby excavated earth are constructed at the same time with the position difference of more than 10m, the pushing equipment is the large bulldozer, and the earth transportation equipment is the self-unloading truck, wherein the purchased mountain clay is directly transported to the specified position in front of the cofferdam after being loaded from the material source site, the nearby excavated earth is transported to the temporary wharf on the right bank of the cofferdam by the bottom barge, and is unloaded after being transported to the front of the cofferdam by the second time, in the land pushing spreading, the embankment top axis and width are reviewed in time to ensure that the embankment core is straight and centered.

[0012] The present application has the following beneficial effects: (1) The water filling and land filling are combined to accelerate the cofferdam forming, the whole process is optimized and combined according to the construction characteristics of the water filling and land filling, each has its own advantages, the problem of the clay filling cofferdam which is easy to be submerged by the land excavation and land pushing equipment is solved, the cofferdam forming and compaction are accelerated, and the relatively tight construction period is saved.

[0013] (2) The inland conventional equipment is used in the water construction, the construction organization is convenient, the backhoe dredger and the grab dredger which are commonly used for excavating earth in inland are used, the ship has shallow draft, is convenient for inland transportation, is positioned by the steel pile positioning method, does not occupy the limited width of the river, and does not occupy the anchor / anchor preparation work for a long time, and is convenient and fast to transfer.

[0014] (3) The ship equipment is not affected by weather, and continuous operation can be realized, time limit is saved, and the weather in the south is rainy, the water level difference between the flood season and the dry season is large, the land excavation construction equipment is limited, especially the clay soil, the water content is already high, and the soil softening degree is increased under the influence of rainfall, the land excavation and land pushing equipment all have a large subsidence or submergence risk, the reverse shovel dredger and grab dredger are used for construction, the cost of equipment and time limit is considered, the construction cost is not increased much, the weather is not affected, 24 hours continuous operation can be realized, the time limit is saved, and it is especially suitable for the construction of water conservancy projects in the south.

[0015] (4) The water overturning and throwing construction reduces the soil disturbance and facilitates the throwing and filling out of water, the soil for the cofferdam overturning and throwing is taken from the soil above the nearby water surface with low water content, the bottom barge transportation and grab ship throwing and filling are used, the soil disturbance and secondary water passing are reduced, and the soil properties are affected, the cofferdam forming and stability can be accelerated; meanwhile, the problem that the cofferdam cannot be thrown and filled out of water by the open body mud barge is solved.

[0016] (5) The cofferdam dike core reinforcing structure can improve the overall stability of the cofferdam, after the cofferdam is thrown and filled out of water, the reverse shovel extrusion silt principle is used for the land pushing external purchased mountain skin clay layering paving, rolling construction, the purpose of hard soil to soft soil is realized, the soft soil is extruded and discharged, the external purchased hard soil is gradually submerged and layered filling and heightening, finally, the stable dike core and the external natural gentle slope are formed after the settlement is stable, and the natural stability of the cofferdam structure is greatly ensured.

[0017] (6) The existing soil is used to the maximum, the soil balance is realized, the cost is saved, and the environment is protected, the method fully uses the nearby excavation soil, saves the fees such as land acquisition, external purchased mountain skin clay mining and transportation, and water and soil conservation, the influence on the surrounding residents production and life is greatly reduced, and good social and economic benefits are obtained. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 It is a construction method schematic view of the cofferdam water-land construction rapid filling method suitable for the cofferdam with clay soil as the soil taking point. DETAILED DESCRIPTION

[0019] The application will be further described in combination with the drawings and specific embodiments.

[0020] For example, the beach, there is no large storage of qualified soil around the project, the direct cofferdam cannot be used by using the storage soil, the designated soil taking area is clay, there is no road around for passing, and the local weather is rainy all the year round, the water is submerged during the flood season, and the like, so that the land excavation and land pushing equipment all have a large subsidence or submergence risk and cannot complete the cofferdam, the conventional cofferdam filling process cannot meet the needs of engineering construction, therefore, in combination with the soil source and characteristics, on the basis of the conventional water and land throwing and filling process, the water-land combined cofferdam water-land construction rapid filling method suitable for the cofferdam with clay soil as the soil taking point is innovatively put forward.

[0021] As Figure 1 shown, a cofferdam water-land construction rapid filling method suitable for the cofferdam soil point is clay, the main technical principle includes underwater throwing filling, water turning filling and land filling dike core.

[0022] (1) Underwater throwing filling: using backhoe dredger to take soil nearby (avoiding the risk of large subsidence or submersion of land excavation and land pushing equipment), using open body mud barge to load and transport soil, and throwing filling to the nearby water surface at the specified location of the cofferdam.

[0023] (2) Water turning filling: using grab dredger operation which is not affected by rainy weather and grab can rotate 360 degrees, taking soil from one side mud barge and rotating to the other side of the cofferdam to be built to throw soil, until the soil is thrown out of water, solving the problem of cofferdam throwing filling out of water, and avoiding the secondary water disturbance of excavated soil, reducing the influence on soil quality parameters and characteristics.

[0024] (3) Land filling dike core: after the cofferdam throwing filling out of water, using land layer filling to fill the purchased mountain skin clay, forming an 8m wide dike core. When layer filling, the cofferdam body soft soil layer is compressed and thinned, and the soil is extruded to form a stable natural slope, forming an effective dike core protection structure, and the dike core is replaced by stable soil to ensure the stability of the cofferdam structure.

[0025] Optimized design of cofferdam structure, (1) cofferdam length: in order to speed up the filling progress, the longer cofferdam can be divided into three sections along the length direction; (2) cofferdam width: the cofferdam adopts slope structure, the cofferdam width is less than the design width, according to the principle of "excavation and filling balance, material saving and environmental protection", the cofferdam width can be appropriately increased during construction to increase the filling amount; (3) cofferdam height: after the cofferdam throwing filling out of water, the cofferdam is paved and rolled in 50cm layer until the cofferdam top to ensure the compactness of the cofferdam structure, the cofferdam top elevation is 21m, considering the settlement factor of newly built cofferdam, the throwing filling height is controlled with 20-30cm excess amount; (4) cofferdam slope ratio: according to the soil condition, the cofferdam design slope is optimized to 1:4 on the leeside and 1:5 on the water side, the slope control during construction should not be greater than the design slope ratio; (5) cofferdam compactness: the compactness should not be less than 90%, each construction layer 50m sets a detection point, the qualified rate should not be less than 80%, the unqualified points should not be concentrated, and the unqualified compactness should not be less than 96% of the design value.

[0026] The body process of underwater throwing filling is as follows: (1) Backhoe dredger pull soil: first in the diversion channel area on the measured layout diversion channel excavation bottom edge line, inserted flagpole as a guide to the excavation, then use backhoe dredger along the excavation line from the diversion channel two ends (with the river diversion channel interface import and export) to the middle of the diversion channel excavation, excavation layer, strip, each layer thickness not more than 2m, each strip width is the shovel into the water when the front of the working diameter, strip and strip overlap is not less than 1m, to avoid missing. Construction around the dredger set warning float.

[0027] (2) Open body barge cofferdam underwater fill: fill when the earthworks using open body barge loading and transportation, open body barge after loading low speed navigation to the cofferdam water, rough positioning after open body fill, barge loading can not exceed the full load water line, navigation attention to wind speed, water flow, navigation route should be fixed, with other vessels to do well to avoid measures, barge fill before measuring the water depth, to avoid fill stranded.

[0028] Water fill construction process as follows: cofferdam fill to the cofferdam near the water surface, when the water level is too shallow barge can not navigate to the cofferdam cofferdam above, use grab dredger cofferdam positioning flip fill construction, construction, first grab dredger positioning in the cofferdam fill position side, then use backhoe dredger from the nearby water above the relatively good soil, through the bottom barge to the cofferdam construction area, bottom barge parked outside the grab dredger, then use the grab dredger on the barge from the bottom to take soil, rotate to the other side of the cofferdam above the fixed point fill height, until the cofferdam fill out of the water surface can not continue to add height.

[0029] Land embankment construction process as follows: land embankment filling, cofferdam fill out of the water surface using land push equipment according to 50cm layer paving purchased mountain clay to form a stable embankment, while taking advantage of extrusion principle cofferdam cofferdam soft soil layer extrusion thin, part of the soil extrusion form stable natural slope, effectively protect the embankment structure, while the embankment is replaced by stable soil, to ensure the stability of the cofferdam structure.

[0030] To speed up the efficiency of land filling, further use of nearby soil construction, cofferdam from the end of the purchased mountain clay layer land push construction at the same time, excavation of nearby soil synchronous reinforcement cofferdam slope, purchased mountain clay and nearby excavation soil before and after 10m above the mileage construction, push filling equipment using large bulldozers, earthmoving equipment using dump trucks, which purchased mountain clay by the source site loading after direct transportation to the cofferdam front designated position unloading, nearby excavation soil by bottom barge transportation to the cofferdam right bank temporary wharf, two times to the cofferdam front unloading, land push paving, timely review embankment axis and width, if the width is insufficient or axis deviation, timely correction, to ensure the embankment straight center.

[0031] The land embankment is rolled, the purchased mountain skin clay is pushed and filled after the cofferdam is filled out of the water surface, at the same time, the rear has been laid flat surface is rolled by the road roller in layers, the cofferdam is settled and solidified, the settlement data is observed in real time, the time when the cofferdam enters the stable state is analyzed, and preparation is made for the subsequent cofferdam closed gas.

[0032] The soil near the two sides of the cofferdam is widened and sloped after the cofferdam is successfully completed, the automatic monitoring and early warning equipment of the cofferdam is installed, and the finishing work such as inspection and acceptance is completed.

[0033] The above only describes the preferred embodiments of the present application, and is not used to limit the present application, any modification, equivalent replacement and improvement within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A rapid filling method for cofferdam construction in both land and water, applicable to soil borrowing sites where the soil is cohesive, characterized in that, Includes the following steps: A. Underwater dumping: Soil is taken from nearby areas using a backhoe dredger, transported by open-body mud barges, and dumped onto the adjacent water surface at the designated location of the cofferdam. B. Water-based filling: Taking advantage of the fact that grab dredgers are not affected by rainy weather and that the grab bucket can rotate 360 ​​degrees, soil is taken from the bottom-sealed mud barge on one side and rotated to the proposed cofferdam on the other side to dump the soil until it is dumped out of the water. C. Land filling of the dike core: After the cofferdam is filled out of the water, purchased mountain clay is used to fill the dike core in layers on land to form an 8m wide dike core. During the layer filling, the soft soil layer of the cofferdam body is compressed and thinned, and the soil is squeezed outward to form a stable natural gentle slope, forming an effective dike core protection structure. The dike core is replaced with stable soil.

2. The rapid filling method for cofferdam construction in water and land areas suitable for soil extraction points of cohesive soil, as described in claim 1, is characterized in that: The underwater backfilling method in step A includes: dredging soil using a backhoe dredger; first, measuring and marking the bottom edge of the open channel in the diversion channel area, and planting colored flagpoles as excavation guides; then, using a backhoe dredger to excavate along the excavation line from both ends of the open channel towards the middle, excavating in layers and strips, with each layer ≤2m thick and each strip width equal to the working diameter of the front edge of the bucket when it reaches underwater, with an overlap of ≥1m between strips to avoid missed excavations; and setting up warning buoys around the dredger during construction; and also includes underwater backfilling using open-body barges for cofferdam construction. During backfilling, the soil is loaded and transported using open-body barges. After loading, the open-body barges sail at low speed to the cofferdam area, perform rough positioning, and then open and dump the soil. The open-body barges must not exceed their full-load draft during loading, and attention must be paid to wind speed and current during navigation. The navigation route should be fixed, and avoidance measures should be taken against other vessels. Before backfilling, the water depth at the bottom of the open-body barge should be measured to avoid grounding.

3. The rapid filling method for cofferdam construction in water and land areas suitable for soil extraction points of cohesive soil, as described in claim 1, is characterized in that: The construction process of step B, water-based backfilling, includes underwater backfilling of the cofferdam to near the water surface. When the water level is too shallow for open-body barges to navigate to the top of the cofferdam, a grab dredger is used for positioning, backfilling, and heightening of the cofferdam. During construction, the grab dredger is first positioned on the side of the cofferdam backfilling location. Then, a backhoe dredger is used to extract relatively good soil from nearby areas above the water surface and transport it to the cofferdam construction area via a bottom-sealing barge. The bottom-sealing barge is moored on the outside of the grab dredger. Then, the grab bucket on the dredger is used to extract soil from the bottom-sealing barge and rotate to the other side of the cofferdam for fixed-point backfilling and heightening until the cofferdam can no longer be heightened after backfilling above the water surface.

4. The rapid filling method for cofferdam construction in water and land areas suitable for soil extraction points of cohesive soil, as described in claim 1, is characterized in that: The construction method of step C, the land filling of the dike core, includes the construction of the land filling dike core. After the cofferdam is filled out of the water surface, the purchased mountain clay is spread in layers of 50cm to form an 8m wide stable dike core. At the same time, the softened soil layer of the cofferdam body is squeezed thinned by the principle of silt squeezing, and part of the soil is squeezed out to form a stable natural gentle slope, while the dike core is replaced with stable soil.

5. A rapid filling method for cofferdam construction in water and land areas where the soil extraction point is cohesive soil, as described in any one of claims 1-4, characterized in that: While the cofferdam is being constructed by layering and pushing the purchased mountain clay from the end, the nearby soil is being excavated to reinforce the slopes on both sides of the cofferdam. The purchased mountain clay and the nearby excavated soil are staggered by more than 10 meters and constructed simultaneously. Large bulldozers are used for pushing and filling, and dump trucks are used for earthwork transportation. The purchased mountain clay is loaded at the material source site and transported directly to the designated location at the front of the cofferdam for unloading along the access road. The nearby excavated soil is transported to the temporary wharf on the right bank of the cofferdam via a bottom-sealing barge, and then transported again to the front of the cofferdam for unloading. During the land-pushing and spreading, the axis and width of the dike top are checked in a timely manner to ensure that the dike core is straight and centered.

Images