Combined earth-rock cofferdam structure and construction method thereof

Abstract

The application belongs to the technical field of hydraulic engineering, and particularly relates to a combined earth-rock cofferdam structure and a construction method thereof. The cofferdam structure comprises a plurality of first-layer plane retaining wall steel plates arranged side by side, a plurality of heightened plane retaining wall steel plates arranged side by side and an earth-rock body. A plurality of steel beams are fixed to the outer side of each first-layer plane retaining wall steel plate. The part of the first-layer plane retaining wall steel plate below the steel beams is inserted into the river bottom bed soil. At least one heightened plane retaining wall steel plate is detachably connected to the upper part of the first-layer plane retaining wall steel plate. The earth-rock body is filled layer by layer on the outer side of the first-layer plane retaining wall steel plate and the heightened plane retaining wall steel plate. The cofferdam structure can effectively utilize the on-site excavated earth-rock materials and save costs. The cofferdam foundation pit does not need to be sloped, and the planar size of the cofferdam is saved. The cofferdam does not need support, and the construction is convenient. The steel structure can be reused, and is ecological and environmentally friendly. The cofferdam body structure has good anti-seepage performance, and the drainage engineering quantity in the foundation pit is small.

Description

Technical Field

[0001] This invention belongs to the field of water conservancy engineering technology, and in particular relates to a combined earth-rock cofferdam structure and its construction method. Specifically, it is a steel structure and earth-rock combined cofferdam structure suitable for the field of water conservancy engineering construction technology, and a construction method for the structure. Background Technology

[0002] A cofferdam is a temporary retaining structure built in water conservancy projects to construct permanent water facilities. Its function is to prevent water and soil from entering the foundation pit of the proposed structure, while simultaneously draining the water within the cofferdam to create dry conditions for excavation and construction. Cofferdams are generally dismantled after use, except when they are part of a permanent structure. Based on the main materials used, cofferdams can be classified into earth-rock cofferdams, concrete cofferdams, and sheet pile cofferdams, among others.

[0003] Earth-rock cofferdams are cofferdams constructed from earth and rock. They can be combined with diversion embankments, utilize excavated waste, and can be constructed rapidly and mechanized using the main excavation and transportation equipment. They are the most widely used type of cofferdam in my country. However, earth-rock cofferdams have relatively low scour resistance and require a large area, generally used for transverse cofferdams. However, in wide riverbeds, with reliable scour protection measures, they can also be used for longitudinal cofferdams. Furthermore, earth-rock cofferdams are generally not used as overflow cofferdams. Concrete cofferdams are generally used on rocky riverbeds without overburden and where water pressure is high. Their main characteristics are scour resistance, high safety, and good impermeability, making them suitable as part of permanent structures. However, construction is more difficult and costly. When concrete cofferdams are used as temporary structures, the subsequent demolition work is extensive, and the waste concrete blocks cause environmental pollution and resource waste. Steel sheet pile cofferdams consist of interlocking steel sections, support rods, and connectors, assembled and fixed to form a robust water-retaining protective wall. Sheet pile cofferdams are durable, flexible, and highly adaptable, and have a wide range of applications. However, sheet pile cofferdams require longitudinal and transverse supports inside the cofferdam body, and diagonal supports may be necessary, which occupies internal space. In addition, the planar dimensions of the cofferdam should not be too large, and it is often used for the construction of water structures with small planar dimensions, such as bridge foundations.

[0004] Therefore, given the shortcomings of the aforementioned earth-rock cofferdams, concrete cofferdams, and sheet pile cofferdams, there is an urgent need to design a combined earth-rock cofferdam structure and its construction method to overcome the deficiencies of the existing technologies. Summary of the Invention

[0005] The purpose of this invention is to provide a combined earth-rock cofferdam structure and its construction method, which can effectively utilize excavated earth and rock materials on site and save costs; no slope is required in the cofferdam foundation pit, saving the planar dimensions of the cofferdam; there is no support inside the cofferdam, making construction convenient; the steel structure can be reused, which is ecological and environmentally friendly; the cofferdam structure has good seepage prevention performance and the amount of drainage work in the foundation pit is small.

[0006] Therefore, the technical solution adopted by the present invention is as follows:

[0007] In a first aspect, the present invention provides a combined earth-rock cofferdam structure, comprising: a plurality of first-layer planar retaining wall steel plates arranged side by side, a plurality of raised planar retaining wall steel plates arranged side by side, and earth and rock mass. A plurality of steel beams are fixed to the outer side of each of the first-layer planar retaining wall steel plates. The portions of the first-layer planar retaining wall steel plates below the steel beams are inserted into the riverbed soil. At least one layer of raised planar retaining wall steel plates is detachably connected to the upper part of the first-layer planar retaining wall steel plates. Adjacent first-layer planar retaining wall steel plates and adjacent raised planar retaining wall steel plates on the same layer are connected by connectors. The earth and rock mass is filled in layers on the outer side of the first-layer planar retaining wall steel plates and the raised planar retaining wall steel plates.

[0008] Furthermore, it also includes several steel strands and several anchor steel plates. One end of the steel strand is connected to the first-layer planar retaining wall steel plate or the heightened planar retaining wall steel plate, and the other end of the steel strand is connected to the anchor steel plate, which is embedded in the soil and rock.

[0009] Furthermore, welded anchor holes are provided on both the first-layer planar retaining wall steel plate and the heightened planar retaining wall steel plate, and the steel strands are fixedly connected to the welded anchor holes.

[0010] Furthermore, screw holes are provided on the upper part of the first-layer flat retaining wall steel plate, the upper part and the lower part of the heightened flat retaining wall steel plate, and the first-layer flat retaining wall steel plate and the heightened flat retaining wall steel plate of the upper and lower layers are connected by bolts inserted through the screw holes.

[0011] Furthermore, one side of the connector is fixedly connected to the first-layer planar retaining wall steel plate or the heightened planar retaining wall steel plate, and the other side of the connector is provided with a vertical combination groove, with adjacent first-layer planar retaining wall steel plates or adjacent heightened planar retaining wall steel plates confined within the combination groove.

[0012] Furthermore, vertical combination grooves are provided on both sides of the connector, and two adjacent first-layer planar retaining wall steel plates or two adjacent raised planar retaining wall steel plates are confined within the combination grooves.

[0013] Furthermore, the bottom of the first-layer planar retaining wall steel plate is formed with a cutting edge.

[0014] Furthermore, a reinforcing triangular steel plate is connected between the steel beam and the first-floor planar retaining wall steel plate.

[0015] Furthermore, geotextile fabric is laid on the soil and rock mass.

[0016] Secondly, the present invention also provides a construction method for the combined earth-rock cofferdam structure described in the first aspect, comprising the following steps:

[0017] Step 1: Design of composite earth-rock cofferdam structure: Based on the requirements of dry construction conditions and water conditions in the construction area, design the geometry, plan dimensions, and elevation of the cofferdam, and refine the subdivision design of the steel structure to obtain the size specifications and quantity requirements of the first-layer plan retaining wall steel plate, the heightened plan retaining wall steel plate, steel beams, reinforcing triangular steel plates, steel strands, bolts, and anchor steel plates.

[0018] Step 2: Fabrication of steel structure components;

[0019] Step 3: Assembly of the first-floor retaining wall steel plates: According to the design requirements, the steel structure components are assembled into a steel structure modular unit on the bank slope near the proposed cofferdam.

[0020] Step 4: Clean the bottom of the underwater cofferdam area;

[0021] Step 5, Positioning and Installation of the First-Layer Plane Retaining Wall Steel Plate: The assembled steel structure unit is hoisted to the designated area in the water. After position calibration, the first-layer plane retaining wall steel plate is driven into the riverbed soil using a vibratory pile driver.

[0022] Step 6: Fill the earth and rock mass;

[0023] Step 7: Raise the cofferdam structure: On the upper part of the first-floor retaining wall steel plate, the cofferdam structure is further raised by bolting the upper retaining wall steel plate, and the earth and rock filling is completed until the cofferdam structure reaches a safe water-blocking height.

[0024] Step 8: Cover with geotextile.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] One of the advantages of this invention is that the weir body is composed of a steel structure and soil and rock mass, which has high rigidity and good impermeability, forming a typical gravity-type water-retaining cofferdam. It does not require internal support and can provide a spacious construction space.

[0027] The second advantage of this invention is that the inner side of the dam body does not need to be sloped, which saves the planar dimensions of the cofferdam and also saves the amount of earth and stone filling.

[0028] The third advantage of this invention is that the weir body is composed of steel sections and earth and rock; the steel sections are uniformly produced and supplied by the factory, and the specifications and models do not need to be customized separately, making processing convenient and reusable;

[0029] The fourth advantage of this invention is that by using the waste soil and rock materials excavated during construction to fill the dam body, the on-site materials are fully utilized, saving material costs, transportation costs, etc. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of one embodiment of the cofferdam structure described in this invention;

[0031] Figure 2 This is a structural schematic diagram of the steel plate retaining wall on the first floor.

[0032] Figure 3 A schematic diagram showing the splicing of the retaining wall steel plates along the axis of the cofferdam.

[0033] Figure 4 This is a structural schematic diagram of the steel beam;

[0034] Figure 5 A structural diagram to reinforce the triangular steel plate;

[0035] Figure 6 A structural diagram of the steel plate for raising the flat retaining wall;

[0036] Figure 7 This is a schematic diagram of the anchor steel plate structure;

[0037] Figure 8 This is a structural schematic diagram of the combined units of the steel structure section;

[0038] Figure 9 This is a flowchart of the construction method described in this invention;

[0039] Figure 10 This is a schematic diagram of another embodiment of the cofferdam structure described in this invention;

[0040] Figure 11 This is a diagram showing the arrangement of the first-floor planar retaining wall steel plate and the heightened planar retaining wall steel plate in another embodiment.

[0041] The components in the diagram are as follows: 1. First-floor retaining wall steel plate; 2. Steel beam; 3. Reinforcing triangular steel plate; 4. Heightened retaining wall steel plate; 5. Steel strand; 6. Anchor steel plate; 7. Geotextile; 8. Soil and rock mass; 9. Riverbed subgrade soil; 10. Connector; 101. Combined trench; 11. Bolt hole; 12. Welded anchor hole; 13. Bolt; 14. Connecting plate; 15. Through hole. Detailed Implementation

[0042] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but this is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention. Example 1

[0043] See appendix Figure 1 - Appendix Figure 8 This embodiment proposes a combined earth-rock cofferdam structure, including several parallel-arranged first-layer planar retaining wall steel plates 1, several parallel-arranged raised planar retaining wall steel plates 4, and earth-rock mass 8. Several steel beams 2 are fixed to the outside of each first-layer planar retaining wall steel plate 1. Reinforcing triangular steel plates 3 are connected between the steel beams 2 and the first-layer planar retaining wall steel plates 1. The portions of the first-layer planar retaining wall steel plates 1 below the steel beams 2 are inserted into the riverbed subgrade soil 9. A layer of raised planar retaining wall steel plates 4 is detachably connected to the upper part of the first-layer planar retaining wall steel plates 1. Adjacent first-layer planar retaining wall steel plates 1 and adjacent raised planar retaining wall steel plates 4 on the same layer are connected by connectors 10. The earth-rock mass 8 is filled in layers on the outside of the first-layer planar retaining wall steel plates 1 and the raised planar retaining wall steel plates 4. Geotextile 7 is laid on the earth-rock mass 8.

[0044] It should be noted that although this embodiment only shows one layer of raised planar retaining wall steel plate 4, the specific number of layers of raised planar retaining wall steel plate 4 needs to be adaptively set according to the design requirements of the water blocking height, such as three layers, four layers, five layers, etc.

[0045] from Figure 1 It can also be seen that the cofferdam structure of the present invention further includes several steel strands 5 and several anchor steel plates 6. One end of the steel strand 5 is connected to the first-layer planar retaining wall steel plate 1 or the heightened planar retaining wall steel plate 4, and the other end of the steel strand 5 is connected to the anchor steel plate 6. The anchor steel plate 6 is buried in the soil and rock mass 8.

[0046] Based on the above structural description, the cofferdam structure of this invention consists of a first-layer planar retaining wall steel plate 1, steel beams 2, reinforcing triangular steel plates 3, heightened planar retaining wall steel plates 4, steel strands 5, anchor steel plates 6, erosion-resistant geotextile 7, and soil and rock mass 8. Specifically:

[0047] The first-layer planar retaining wall steel plate 1 is as follows Figure 2 The diagram shows a plate-like structure used to form the water-retaining and soil-retaining structure of the cofferdam. The lower edge of the first-layer planar retaining wall steel plate 1 has a cutting edge for easy insertion into the riverbed soil layer. The upper part of the first-layer planar retaining wall steel plate 1 is provided with no less than two rows of bolt holes, which facilitates the connection of the cofferdam structure to be heightened by bolts 13 according to the height requirements of the cofferdam.

[0048] The steel beam 2 refers to the component that is vertically welded to the outside of the retaining wall steel plate 1 on the first floor, forming a toe-like structure, such as... Figure 4 As shown, steel beam 2 needs to be welded to the end of the first-floor retaining wall steel plate 1 near the edge with the cutting edge. The depth of the steel plate embedded in the riverbed needs to be determined according to the soil conditions of the riverbed base layer, so that steel beam 2 is located above the depth of the first-floor retaining wall steel plate 1 embedded in the riverbed. Steel beam 2 can be made of H-shaped steel with a height of 450mm, a width of 450mm, a web thickness of 34mm, and a flange thickness of 36mm.

[0049] The reinforcing triangular steel plate 3 refers to the component that connects the steel beam 2 and the first-floor retaining wall steel plate 1 by welding, such as... Figure 5 As shown, this is to enhance the bending stiffness of the steel plate 1 of the first-floor retaining wall.

[0050] The heightened planar retaining wall steel plate 4 refers to a component used to increase the height of the retaining wall steel plate according to the design height of the cofferdam, such as... Figure 6 As shown.

[0051] The steel strand 5 refers to the metal rope used to connect the first-floor retaining wall steel plate 1 or the heightened retaining wall steel plate 4 and the anchor steel plate 6. It is flexible and can adapt to the deformation requirements of the backfill soil. Figure 1 and Figure 8 As shown.

[0052] The anchor steel plate 6 refers to the component that forms an anchoring structure with the steel strand 5, used to increase the anchoring force and prevent the retaining wall steel plate from tilting or deforming. It can be made of steel plates of any shape with small planar dimensions by drilling holes, such as... Figure 7 As shown. The first-floor planar retaining wall is assembled from steel plate 1, steel beam 2, reinforcing triangular steel plate 3, steel strand 5, and anchor steel plate 6 to form the following structure. Figure 8 The spatial system shown.

[0053] The erosion-resistant geotextile 7 refers to a layer of geotextile fabric laid on the water-facing slope of the soil and rock mass 8 to prevent water flow from eroding the filled soil.

[0054] The soil and rock mass 8 refers to the waste soil and rock material excavated at the construction site of the water conservancy project, which is directly filled in layers on the outside of the first-layer flat retaining wall steel plate 1 and the heightened flat retaining wall steel plate 4, and compacted to form a gravity retaining wall, such as... Figure 1 As shown.

[0055] To facilitate the connection between the steel strand 5 and the first-floor retaining wall steel plate 1 or the heightened retaining wall steel plate 4, welded anchor holes 12 are provided on both the first-floor retaining wall steel plate 1 and the heightened retaining wall steel plate 4. The steel strand 5 is fixedly connected to the welded anchor holes 12. In specific implementation, welded anchor holes 12 for the steel strand 5 are provided on the soil-rock side of the first-floor retaining wall steel plate 1 and the heightened retaining wall steel plate 4 by welding, which facilitates fixing the anchor steel plate with the steel strand. Please refer to [link to details]. Figure 1 and Figure 8 .

[0056] In some other embodiments, the connection between the steel strand 5 and the first-layer flat retaining wall steel plate 1 or the heightened flat retaining wall steel plate 4 can also be achieved by bolting after holes are made in the first-layer flat retaining wall steel plate 1 or the heightened flat retaining wall steel plate 4.

[0057] Furthermore, the connection method between the steel strand 5 and the anchor plate 6 can be as follows: Figure 7 The method shown is to insert and fix the steel strand 5 after making a hole in the anchor plate 6. Alternatively, the anchor hole 12 can be welded to the anchor plate 6 to achieve a fixed connection, which will not be elaborated here.

[0058] In specific implementation, screw holes 11 are provided on the upper part of the first-layer flat retaining wall steel plate 1, and on the upper and lower parts of the raised flat retaining wall steel plate 4. The first-layer flat retaining wall steel plate 1 and the raised flat retaining wall steel plate 4, as well as the raised flat retaining wall steel plates 4 of the upper and lower layers, are connected by bolts 13 inserted into the screw holes 11. That is, the raised flat retaining wall steel plate 4, like the first-layer flat retaining wall steel plate 1, has connectors 10, screw holes 11, welded anchor holes 12, and other structures. Through the detachable method of screw holes 11 and bolts 13, the required number of raised flat retaining wall steel plates 4 can be quickly connected above the first-layer flat retaining wall steel plate 1, thereby increasing the height of the weir structure and adapting to water retention requirements at different heights.

[0059] In the specific implementation process, the connector 10 has at least two implementation methods. One method is that one side of the connector 10 is fixedly connected to the first-layer plane retaining wall steel plate 1 or the heightened plane retaining wall steel plate 4, and the other side of the connector 10 is provided with a vertical combination groove 101, and the adjacent first-layer plane retaining wall steel plate 1 or the adjacent heightened plane retaining wall steel plate 4 is limited to the combination groove 101.

[0060] Specifically, the first-layer planar retaining wall steel plate 1 or the heightened planar retaining wall steel plate 4 has a connector 10 on its right side, forming a combination groove 101 on the right side of the connector 10. The connector 10 is formed by welding trapezoidal steel plates to both sides of the steel plate. During the construction of the cofferdam structure, the first-layer planar retaining wall steel plates 1 are assembled together along the cofferdam axis using the combination groove 101 of the connector 10, as shown below. Figure 3 As shown.

[0061] Another implementation is as follows: vertical combination grooves 101 are provided on both sides of the connector 10, and two adjacent first-layer planar retaining wall steel plates 1 or two adjacent raised planar retaining wall steel plates 4 are limited to the combination grooves 101 (not shown in the figure).

[0062] Of course, in actual implementation, this embodiment only shows the slot as a way to quickly construct, and the connection between two adjacent first-floor planar retaining wall steel plates 1 or heightened planar retaining wall steel plates 4 can also adopt other structural forms. Example 2

[0063] like Figure 9 As shown in the figure, this invention proposes a construction method for a combined earth-rock cofferdam structure as described in Example 1, including the design of the combined earth-rock cofferdam structure, fabrication of steel structure components, assembly of the first-layer planar retaining wall steel plate, bottom cleaning of the underwater cofferdam area, positioning and installation of the first-layer planar retaining wall steel plate, filling of earth and rock, raising the cofferdam retaining wall steel plate, and covering with geotextile, etc. The specific steps are as follows:

[0064] Step 1: Design of composite earth-rock cofferdam structure: Based on the requirements of dry construction conditions and water conditions in the construction area, design the geometry, plan dimensions, elevation, etc. of the cofferdam, and further refine the subdivision design of the steel structure to obtain the size specifications and usage requirements of the first-layer plan retaining wall steel plate 1, the heightened plan retaining wall steel plate 4, steel beam 2, reinforcing triangular steel plate 3, steel strand 5, bolt 13, and anchor steel plate 6, and complete the drawing design;

[0065] Step 2, Steel structure component fabrication: According to the design drawings, select steel profiles, cut and prepare them, and weld components such as anchor holes 12, drill screw holes 11, and install bolts 13.

[0066] Step 3: Assembly of the first-floor retaining wall steel plate 1: According to the design requirements, assemble the steel structure components into a steel structure modular unit on the bank slope near the proposed cofferdam, such as... Figure 8 As shown;

[0067] During construction, according to the design requirements, the steel beam 2 is welded and fixed to the outer side of the first-floor retaining wall steel plate 1 to form a toe-shaped structure. Then, the reinforcing triangular steel plate 3 is welded and connected between the steel beam 2 and the first-floor retaining wall steel plate 1. Then, one end of the steel strand 5 is fixedly connected to the welded anchor hole 12 on the first-floor retaining wall steel plate 1, and the other end is fixedly connected to the anchor steel plate 6.

[0068] Step 4: Cleaning the bottom of the underwater cofferdam area: The area where the cofferdam structure will be placed will be cleaned by underwater operations, mainly removing tree roots, silt, stones and debris from the riverbed below the cofferdam.

[0069] Step 5, Positioning and installation of the first-floor retaining wall steel plate 1: The assembled steel structure unit will be hoisted to the designated area in the water using a ship or other machinery. After the position is calibrated, the first-floor retaining wall steel plate 1 will be driven into the riverbed soil 9 using a vibratory pile driver.

[0070] Step 6, Filling the soil and rock mass 8: Use the soil excavated from the onshore construction area to fill the outer side of the first-floor retaining wall steel plate 1, and compact it in layers; at the same time, sort out the steel strands 5 and anchor steel plates 6;

[0071] Step 7: Raise the cofferdam structure: On the upper part of the first-level planar retaining wall steel plate 1, connect the raised planar retaining wall steel plate 4 with bolts 13 to further raise the cofferdam structure, and complete the filling of the soil and rock mass 8 until the cofferdam structure reaches the safe water-blocking height.

[0072] Step 8, Cover with geotextile 7: Cover the water-facing side of the completed earth and rock mass 8 with a layer of geotextile 7 to prevent the earth and rock mass from collapsing due to long-term water erosion. Example 3

[0073] See appendix Figure 10 and attached Figure 11 The difference between this embodiment and Embodiment 1 is that the cofferdam structure further includes a connecting plate 14, with through holes 15 on both the upper and lower sides. Bolts 13 are inserted into the through holes 15, and these bolts 13 are respectively inserted into the upper screw holes 11 of the first-layer planar retaining wall steel plate 1 and the lower or upper screw holes 11 of the heightened planar retaining wall steel plate 4. This achieves the connection between the first-layer planar retaining wall steel plate 1 and the heightened planar retaining wall steel plate 4 via the connecting plate 14, and the connection between the upper and lower heightened planar retaining wall steel plates 4 via the connecting plate. The relationship between the first-layer planar retaining wall steel plate 1 and the heightened planar retaining wall steel plate 4 after connection is as follows: Figure 10 As shown. Through the detachable method of screw holes 11, bolts 13, and through holes 15, the connecting plate 14 can quickly connect the required number of heightened flat retaining wall steel plates 4 above the first-layer flat retaining wall steel plate 1, thereby increasing the height of the weir structure and adapting to water-blocking requirements at different heights.

[0074] In summary, the combined earth-rock cofferdam structure described in this embodiment is composed of steel structures such as the first-layer planar retaining wall steel plate 1, steel beam 2, reinforcing triangular steel plate 3, heightened planar retaining wall steel plate 4, steel strand 5, and anchor steel plate 6, combined with earth and rock mass 8. It has high rigidity and good impermeability, and is a typical gravity-type water-retaining cofferdam. It does not require internal support and provides a spacious construction space. During construction, there is no need to slope the inner side of the cofferdam, which effectively saves the planar dimensions of the cofferdam and the amount of earth and rock fill. The steel profiles used to manufacture the first-layer planar retaining wall steel plate 1, steel beam 2, reinforcing triangular steel plate 3, heightened planar retaining wall steel plate 4, steel strand 5, and anchor steel plate 6 are uniformly produced and provided by the factory. The specifications and models do not need to be customized separately, which is convenient for processing and can be reused. The waste soil and rock material excavated during construction is used to fill the cofferdam to form earth and rock mass 8, making full use of on-site materials and saving material costs and transportation costs.

Claims

1. A composite earth-rock cofferdam structure, characterized in that, It includes several first-layer planar retaining wall steel plates (1) arranged side by side, several raised planar retaining wall steel plates (4) arranged side by side, and soil and rock mass (8). Several steel beams (2) are fixed on the outside of each first-layer planar retaining wall steel plate (1). The portions of several first-layer planar retaining wall steel plates (1) located below the steel beams (2) are inserted into the riverbed foundation soil mass (9). At least one layer of raised planar retaining wall steel plates (4) is detachably connected to the upper part of the first-layer planar retaining wall steel plate (1). Adjacent first-layer planar retaining wall steel plates (1) and adjacent raised planar retaining wall steel plates (4) located on the same layer are connected by connectors (10). The soil and rock mass (8) is filled in layers on the outside of the first-layer planar retaining wall steel plates (1) and the raised planar retaining wall steel plates (4). It also includes several steel strands (5) and several anchor steel plates (6), one end of the steel strands (5) is connected to the first-layer planar retaining wall steel plate (1) or the heightened planar retaining wall steel plate (4), and the other end of the steel strands (5) is connected to the anchor steel plate (6), which is buried in the soil and rock mass (8); Geotextile (7) is laid on the water-facing slope of the soil and rock mass (8).

2. The combined earth-rock cofferdam structure according to claim 1, characterized in that, Welded anchor holes (12) are provided on both the first-layer planar retaining wall steel plate (1) and the heightened planar retaining wall steel plate (4), and the steel strand (5) is fixedly connected to the welded anchor holes (12).

3. The combined earth-rock cofferdam structure according to claim 1, characterized in that, Screw holes (11) are provided on the upper part of the first-layer flat retaining wall steel plate (1), the upper part and the lower part of the heightened flat retaining wall steel plate (4). The first-layer flat retaining wall steel plate (1) and the heightened flat retaining wall steel plate (4) are connected by bolts (13) inserted in the screw holes (11).

4. The combined earth-rock cofferdam structure according to claim 1, characterized in that, One side of the connector (10) is fixedly connected to the first-layer planar retaining wall steel plate (1) or the heightened planar retaining wall steel plate (4), and the other side of the connector (10) is provided with a vertical combination groove (101), and the adjacent first-layer planar retaining wall steel plate (1) or the adjacent heightened planar retaining wall steel plate (4) is limited to the combination groove (101).

5. The combined earth-rock cofferdam structure according to claim 1, characterized in that, The connector (10) has vertical combination grooves (101) on both sides, and two adjacent first-layer planar retaining wall steel plates (1) or two adjacent heightened planar retaining wall steel plates (4) are limited to the combination grooves (101).

6. The combined earth-rock cofferdam structure according to claim 1, characterized in that, The bottom of the first-layer planar retaining wall steel plate (1) has a cutting edge.

7. The combined earth-rock cofferdam structure according to claim 1, characterized in that, A reinforcing triangular steel plate (3) is connected between the steel beam (2) and the first-floor retaining wall steel plate (1).

8. A construction method for a combined earth-rock cofferdam structure as described in any one of claims 1-7, characterized in that... Includes the following steps: Step 1: Design of composite earth-rock cofferdam structure: In view of the requirements of dry construction conditions and water conditions in the construction area, design the geometry, plan dimensions and elevation of the cofferdam, and refine the subdivision design of the steel structure to obtain the size specifications and usage requirements of the first-layer plan retaining wall steel plate (1), heightened plan retaining wall steel plate (4), steel beam (2), reinforced triangular steel plate (3), steel strand (5), bolt (13) and anchor steel plate (6); Step 2: Fabrication of steel structure components; Step 3, Assembly of the first-floor retaining wall steel plate (1): According to the design requirements, the steel structure components are assembled into a steel structure unit on the bank slope near the proposed cofferdam; Step 4: Clean the bottom of the underwater cofferdam area; Step 5, Positioning and installation of the first-floor retaining wall steel plate (1): The assembled steel structure unit is hoisted to the designated area in the water. After the position is calibrated, the first-floor retaining wall steel plate (1) is driven into the riverbed soil (9) by a vibratory pile driver. Step 6: Fill the earth and rock mass (8); Step 7, Raise the cofferdam structure: On the upper part of the first-floor retaining wall steel plate (1), connect the raised retaining wall steel plate (4) with bolts (13) to further raise the cofferdam structure, and complete the filling of the soil and rock mass (8) until the cofferdam structure reaches the safe water-blocking height; Step 8: Cover with geotextile (7).

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