Underwater cofferdam structure close to highway and construction method

Abstract

The invention discloses an underwater cofferdam structure close to a road. The underwater cofferdam structure comprises a plurality of secant piles, an inner supporting mechanism, a first supporting and retaining mechanism, a second supporting and retaining mechanism and a third supporting and retaining mechanism. A foundation pit is arranged on one side of a road, an island is arranged on the foundation pit, a plurality of secant piles on the island form a square cofferdam structure, a bearing platform is arranged on the inner side of the square cofferdam structure, and a plurality of engineering piles are arranged on the bearing platform. The inner supporting mechanisms are arranged at the four corners of the interior of the square cofferdam structure. The first supporting and retaining mechanism is arranged on the side, close to the highway, of the square cofferdam structure. The second supporting and retaining mechanisms are arranged on the two side edges, perpendicular to the road, of the square cofferdam structure. The third supporting and retaining mechanism is arranged on the water facing side of the square cofferdam structure. According to the underwater cofferdam structure close to the highway and the construction method, the existing defects are overcome, the underwater cofferdam structure close to the highway and the construction method can adapt to the complex environment, the structural stability is good, the excavation space is large, and construction safety is guaranteed.

Description

Technical Field

[0001] The present invention relates to a cofferdam structure in water near a highway and a construction method thereof. Background Art

[0002] As an important part of modern transportation, the technological development of high-speed railway bridges is particularly crucial and occupies an important position. They can cross obstacles such as rivers and valleys, ensuring the straightness and high-speed operation of the line.

[0003] Currently, when a bridge needs to cross a large river, deep foundation pits need to be set up for bridge foundation construction. There is no existing suitable structure for the complex and sensitive surrounding environment; when adjacent to structures, a new type or composite cofferdam structure is required to ensure safe construction. Therefore, in view of the above problems, a cofferdam structure in water near a highway and a construction method thereof are proposed. Summary of the Invention

[0004] The purpose of the present invention is to provide a cofferdam structure in water near a highway and a construction method thereof to overcome the existing defects, which can adapt to complex environments, have good structural stability, large excavation space, and ensure construction safety.

[0005] To achieve the above purpose, the present invention provides the following technical solution: A cofferdam structure in water near a highway, comprising multiple secant piles, an internal support mechanism, a first retaining mechanism, a second retaining mechanism, and a third retaining mechanism;

[0006] A foundation pit is arranged on one side of the highway. An artificial island is set on the foundation pit. Multiple secant piles on the artificial island form a square cofferdam structure. A bearing platform is arranged inside the square cofferdam structure, and multiple engineering piles are arranged on the bearing platform;

[0007] The internal support mechanism is arranged at the four corners inside the square cofferdam structure;

[0008] The first retaining mechanism is arranged on the side of the square cofferdam structure close to the highway;

[0009] The second retaining mechanism is arranged on the two side edges perpendicular to the highway of the square cofferdam structure;

[0010] The third retaining mechanism is arranged on the water-facing side of the square cofferdam structure.

[0011] Preferably, the secant piles include multiple reinforced concrete piles and multiple plain concrete piles, and multiple reinforced concrete piles and multiple plain concrete piles are alternately connected and provided with a coping beam at the upper part;

[0012] Six anchor cables are connected to the side of the square cofferdam structure formed by multiple secant piles close to the highway;

[0013] Five cables are connected to the two sides of the square cofferdam structure composed of multiple overlapping bored piles perpendicular to the highway.

[0014] Preferably, the internal support mechanism includes corner braces and a fish-belly beam; the corner braces are connected to the right angles of the square cofferdam structure composed of the multiple overlapping bored piles; the fish-belly beam is connected to the four walls of the square cofferdam structure; the fish-belly beam includes a first fish-belly beam and a second fish-belly beam, and the first fish-belly beam is located above the second fish-belly beam; the first fish-belly beam and the second fish-belly beam are connected to column piles.

[0015] Preferably, the first retaining mechanism includes a retaining block, and the retaining block is connected to the side of the overlapping bored pile close to the highway.

[0016] Preferably, the second retaining mechanism includes backfill soil, anchor rods, and a concrete lining; the backfill soil is arranged on the back of the overlapping bored pile, the anchor rods are inserted inside, and the concrete lining is arranged outside.

[0017] Preferably, the third retaining mechanism includes a counterfort flood control wall, and the counterfort flood control wall is arranged on the water-facing side of the square cofferdam structure composed of multiple overlapping bored piles and is located above the coping beam.

[0018] Preferably, a baffle is arranged on one side of the retaining block and the backfill soil, and block stones are piled on the other side of the baffle.

[0019] A construction method for a cofferdam structure in water near a highway includes the following steps:

[0020] Step 1, island building construction;

[0021] In the river part within the construction scope of the foundation pit, mountain skin soil and tunnel slag are filled, and the filling range is 5.0 m outside the edge of the foundation pit, and it is protected by grouted block stones or fine aggregate concrete; then on-site investigation is carried out before island building to check the on-site hydrogeological conditions, select and prepare cohesive soil materials; then according to the drawings, cofferdam design, etc., measurement lofting is carried out, benchmark poles are inserted to determine the position of the cofferdam; then mechanical stone throwing follows the order of "near first, point first, line later, shallow water area first, deep water area later", step by step, and layered throwing is carried out; then soil is filled and compacted. When filling cohesive soil on the cofferdam platform, attention should be paid to layered filling and compaction. The island surface is filled with cohesive soil to create conditions for pile foundation construction;

[0022] Step 2, overlapping bored pile construction;

[0023] First, cast-in-place concrete piles are constructed, and then reinforced concrete piles are constructed; multiple reinforced concrete piles and multiple cast-in-place concrete piles are alternately connected to form a square cofferdam structure;

[0024] Step 3, retaining structure construction;

[0025] On one side of the square cofferdam structure composed of multiple overlapping bored piles close to the road, set a retaining block, and set a baffle outside the retaining block. After the construction of the baffle is completed, drive three anchor cables from top to bottom in a timely manner;

[0026] On both sides of the square cofferdam structure composed of multiple overlapping bored piles perpendicular to the road, set backfill soil, insert anchor rods into the backfill soil, and set a concrete facing on the outside. Then set a baffle outside the backfill soil. After the construction of the baffle is completed, drive two anchor cables from top to bottom in a timely manner;

[0027] On the water-facing side of the square cofferdam structure composed of multiple overlapping bored piles, set a counterfort type flood control wall;

[0028] Step 4: While excavating, install the internal support mechanism and drive the anchor cables;

[0029] First, drive the first anchor cable, then excavate downward, set corner braces at the right angles of the square cofferdam structure, and set the first fish-belly beam on the four walls of the square cofferdam structure;

[0030] Continue to excavate downward, set the second fish-belly beam on the four walls of the square cofferdam structure, and then drive the second anchor cable;

[0031] Continue to excavate downward, and then drive the third anchor cable;

[0032] Continue to excavate to the required depth, set column piles, connect the upper ends of the column piles to the first fish-belly beam and the second fish-belly beam, and then carry out the construction of the bearing platform and engineering piles.

[0033] Compared with the prior art, the beneficial effects of the present invention are as follows: For the underwater cofferdam structure and construction method adjacent to the road of the present invention, by setting multiple overlapping bored piles, an internal support mechanism, a first retaining mechanism, a second retaining mechanism and a third retaining mechanism; by setting different internal support structures and retaining structures respectively under various working conditions such as adjacent to the road and facing the water, it can adapt to complex environments, has good structural stability, a large excavation space, and ensures construction safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The drawings are used to provide a further understanding of the present invention, and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention, and do not constitute a limitation to the present invention. In the drawings:

[0035] Figure 1 is the surrounding environment diagram of the foundation pit of the underwater cofferdam structure and construction method adjacent to the road of the present invention;

[0036] Figure 2 is the plan view of the first corner brace of the underwater cofferdam structure and construction method adjacent to the road of the present invention;

[0037] Figure 3This is the plan view of the second and third fish-belly beams of the underwater cofferdam structure and construction method near the road of the present invention;

[0038] Figure 4 This is a schematic diagram of the first retaining mechanism of the underwater cofferdam structure and construction method near the road of the present invention;

[0039] Figure 5 This is a schematic diagram of the second retaining mechanism of the underwater cofferdam structure and construction method near the road of the present invention;

[0040] Figure 6 This is a schematic diagram of the third retaining mechanism of the underwater cofferdam structure and construction method near the road of the present invention;

[0041] Figure 7 This is a schematic diagram of the secant pile of the underwater cofferdam structure and construction method near the road of the present invention.

[0042] In the figure: 1. Road; 2. Shoreline; 3. Filling island; 4. Engineering pile; 5. Cap; 6. Secant pile; 6-1. Reinforced concrete pile; 6-2. Plain concrete pile; 7. Anchor cable; 8. Corner brace; 9. Fish-belly beam; 9-1. First fish-belly beam; 9-2. Second fish-belly beam; 10. Coping beam; 11. Stacked block stones; 12. Baffle; 13. Backfill soil; 14. Anchor rod; 15. Concrete lining; 16. Column pile; 17. Block; 18. Counterfort flood control wall. Detailed implementation manners

[0043] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0044] Please refer to Figures 1-7 , an underwater cofferdam structure near a road, including multiple secant piles 6, an internal support mechanism, a first retaining mechanism, a second retaining mechanism, and a third retaining mechanism; a foundation pit is arranged on one side of the road 1, a filling island 3 is arranged on the foundation pit, multiple secant piles 6 on the filling island 3 form a square cofferdam structure, a cap 5 is arranged inside the square cofferdam structure, and multiple engineering piles 4 are arranged on the cap 5; the internal support mechanism is arranged at the four internal corners of the square cofferdam structure; the first retaining mechanism is arranged on the side of the square cofferdam structure close to the road 1; the second retaining mechanism is arranged on the two side edges perpendicular to the road 1 of the square cofferdam structure; the third retaining mechanism is arranged on the water-facing side of the square cofferdam structure.

[0045] Specifically, Highway 1 is an existing national road, and the closest straight-line distance from the edge of the foundation pit is 2.6 m. The reclamation island 3 is filled outside the shoreline 2 according to the position of the cofferdam, and the main filling material is cohesive soil, and the outer slope ratio is not steeper than 1:1.5. There are a total of 36 engineering piles 4, arranged in a 6×6 pattern, with a pile diameter of 2.5 m and a pile length of 75 m. The pile cap 5 is a double-layer reinforced concrete structure, 37 m in the longitudinal direction of the bridge, 40 m in the transverse direction of the bridge, and 5 m thick.

[0046] Specifically, the secant pile 6 includes multiple reinforced concrete piles 6-1 and multiple plain concrete piles 6-2. The multiple reinforced concrete piles 6-1 and the multiple plain concrete piles 6-2 are alternately connected and arranged, and a coping beam 10 is provided at the upper part; six anchor cables 7 are connected to one side of the square cofferdam structure composed of multiple secant piles 6 close to the highway 1; five anchor cables 7 are connected to the two side edges perpendicular to the highway 1 of the square cofferdam structure composed of multiple secant piles 6.

[0047] Specifically, the reinforced concrete pile 6-1 has a pile diameter of 1 m, a spacing of 1.4 m, and is made of C30 concrete; the plain concrete pile 6-2 has a pile diameter of 1 m, a spacing of 1.4 m, and is made of C20 concrete.

[0048] Specifically, the coping beam 10 is made of C30 reinforced concrete, with a width of 1.3 m and a height of 0.6 m.

[0049] Specifically, the internal support mechanism includes corner braces 8 and cellular beams 9; the corner braces 8 are connected at the right angles of the square cofferdam structure composed of multiple secant piles 6; the cellular beams 9 are connected to the four walls of the square cofferdam structure; the cellular beam 9 includes a first cellular beam 9-1 and a second cellular beam 9-2, and the first cellular beam 9-1 is located above the second cellular beam 9-2; the first cellular beam 9-1 and the second cellular beam 9-2 are connected with column piles 16.

[0050] Specifically, the corner braces 8 are arranged at the four corners of the cofferdam structure, made of H350X350X12X19 steel, with a length of 9 m. The first cellular beam 9-1 is 1.5 m below the corner brace 8, and the second cellular beam 9-2 is 4 m below the first cellular beam 9-1.

[0051] Specifically, the suspended part of the cellular beam 9 is supported by column piles 16. The column piles 16 include cast-in-place piles and steel lattice columns. The steel lattice columns are welded by 4 L160X160X10 angle steels and several flat steels, are fabricated simultaneously with the cast-in-place pile reinforcement cages, are inserted 4.0 m into the cast-in-place piles, and the angle steels and the cast-in-place pile spiral reinforcements are connected by spot welding.

[0052] Specifically, the first retaining mechanism includes a retaining block 17, and the retaining block 17 is connected to one side of the secant pile 6 close to the highway 1. A baffle 12 is provided on one side of the retaining block 17 and the backfill soil 13, and block stones 11 are piled on the other side of the baffle 12.

[0053] Specifically, the baffle 12 is a 300 - mm thick C30 reinforced concrete slab with a steel mesh of diameter 8@200x200 embedded inside, and is set on the outside of the stacked rubble 11 under the road 1. The retaining block 17 is made of C30 reinforced concrete.

[0054] Specifically, the second retaining mechanism includes backfill soil 13, anchor rods 14 and concrete lining 15; the backfill soil 13 is set on the back of the secant pile 6, with anchor rods 14 inserted inside and a concrete lining 15 set outside. A baffle 12 is set on one side of the retaining block 17 and the backfill soil 13, and on the other side of the baffle 12 is the stacked rubble 11.

[0055] Specifically, the backfill soil 13 is set between the secant pile 6 and the baffle 12, with a compaction coefficient not less than 0.94. Anchor rods 14 are inserted and a 100 - mm thick C30 concrete lining 15 is used.

[0056] Specifically, the third retaining mechanism includes a counterfort - type flood - control wall 18, which is set on the water - facing side of the square cofferdam structure composed of multiple secant piles 6 and is located above the coping beam 10.

[0057] Specifically, the counterfort - type flood - control wall 18 is set on the water - facing side, with a wall - board thickness of 0.3 m, a height of 1.5 m, a counterfort bottom width of 0.3 m, and is set at intervals of 1 m.

[0058] A construction method for a water - in - water cofferdam structure adjacent to a road includes the following steps:

[0059] Selection of retaining structures

[0060] Combined with the characteristics of the foundation pit project of this project, the vertical retaining structures that can be adopted are: secant pile retaining structure, SMW - method pile (cement - soil pile + inserted steel section) retaining structure.

[0061]

[0062] From the perspective of cost, the SMW - method pile is more reasonable, but the construction requirements for cement - soil mixing piles are relatively high. First, the island - building method is used to build a drilling platform, and there are problems with relatively large particle sizes in the in - situ cement - soil piles; second, once the foundation pit leaks, the cost of leak repair is too high (the amount of backfill grouting is large). From the construction perspective, the secant pile construction method is relatively mature; from the safety perspective, the secant pile construction has a large stiffness, a single construction equipment, less lifting operations, and at the same time, during construction, the full - casing dry - hole drilling is adopted without a mud circulation system, saving site space and reducing environmental pollution.

[0063] Selection of internal support structures

[0064] Common horizontal support structures for foundation pits include cross - braces (including steel supports and reinforced concrete supports), and pre - stressed assembled fish - belly beams in two forms.

[0065]

[0066] The assembled prestressed fish-belly beam steel structure support technology (IPS method) is a new type of internal support structure system for deep foundation pit support developed based on the prestress principle in response to the deficiencies of traditional concrete internal supports and steel supports through a large number of engineering studies and practical applications.

[0067] The plane size of the main pier foundation pit of this project is 43m×40m, approximately square. The conventional steel supports are densely arranged in space, which is not conducive to earth excavation and transportation; while the cast-in-situ construction and demolition of reinforced concrete supports take a lot of time. These two types of horizontal support structure forms cannot meet the construction period requirements. The main pier of the bridge is located at the water-land junction, with half of the foundation pit on the shore and half in the water. The water pressure and soil pressure borne by the retaining structure are not balanced; at the same time, the water level near the river side changes greatly, and the water pressure is also constantly changing. The force on the water-facing side of the retaining structure shows a dynamic change process. Therefore, through the above comparison and selection, the assembled prestressed fish-belly beam steel support is finally selected as the horizontal support structure for the main pier foundation pit of this project.

[0068] Step 1: Island construction;

[0069] Fill the mountain skin soil and hole slag in the river part within the construction scope of the foundation pit. The filling range is 5.0m outside the foundation pit edge, and protect the slope with grouted rubble or fine aggregate concrete; then conduct on-site investigation before island construction, check the on-site hydrogeological conditions, select and prepare cohesive soil materials; then carry out surveying and setting out according to the drawings, cofferdam design, etc., insert benchmark poles to determine the cofferdam position; then the mechanical stone throwing follows the order of "from near to far, from point to line, from shallow water area to deep water area", and gradually layer by layer; then fill and compact the soil. When filling cohesive soil on the cofferdam platform, pay attention to layered filling and compaction. Fill with cohesive soil under the island surface to create conditions for pile foundation construction.

[0070] Step 2: Secant pile construction;

[0071] First, construct the plain concrete pile 6-2, and then construct the reinforced concrete pile 6-1; alternately connect multiple reinforced concrete piles 6-1 and multiple plain concrete piles 6-2 to form a square cofferdam structure; during construction, the strength of the plain concrete pile 6-2 should meet the drilling requirements of the reinforced concrete pile 6-1. During the construction process, according to the temperature conditions and specific equipment conditions, adjusting the dosage of fly ash and retarder to delay the strength growth within a reasonable range is the key; the reinforced concrete pile 6-1 uses slightly expanding concrete, which can effectively prevent the problem of water seepage.

[0072] Step 3: Retaining structure construction;

[0073] Set a retaining block 17 on one side of the square cofferdam structure composed of multiple secant piles 6 close to the road 1, and set a baffle 12 outside the retaining block 17. After the construction of the baffle 12 is completed, drive three cables 7 from top to bottom in time;

[0074] Backfill soil 13 is set on both sides of the square cofferdam structure composed of multiple overlapping bored piles 6 perpendicular to the road 1. Anchor rods 14 are inserted into the backfill soil 13, and a concrete facing 15 is set on the outside. Then, a baffle 12 is set on the outside of the backfill soil 13. After the construction of the baffle 12 is completed, two cables 7 are driven in time from top to bottom;

[0075] A counterfort flood control wall 18 is set on the water-facing side of the square cofferdam structure composed of multiple overlapping bored piles 6;

[0076] After the construction of the baffle 12 is completed, the cable 7 is driven in time. The parameters are as shown in the following table. The cement mortar uses 42.5-grade ordinary Portland cement, and the water-cement ratio is 0.45 - 0.50. The mix ratio of the cement mortar is: cement: water: sand: admixture = 1: 0.47: 2: 0.06 (the admixture is concrete expansion agent).

[0077]

[0078] The parameters of the cable 7 section are as shown in the following table:

[0079]

[0080] Step 4: While excavating, install the internal support mechanism and drive the cable;

[0081] First, drive the first cable 7, then excavate downward, and set a corner brace 8 at the right angle of the square cofferdam structure, and set the first fish-belly beam 9-1 on the four walls of the square cofferdam structure;

[0082] Continue to excavate downward, set the second fish-belly beam 9-2 on the four walls of the square cofferdam structure, and then drive the second cable 7;

[0083] Continue to excavate downward, and then drive the third cable 7;

[0084] Continue to excavate to the required depth, set the column pile 16, connect the upper end of the column pile 16 to the first fish-belly beam 9-1 and the second fish-belly beam 9-2, and then carry out the construction of the bearing platform 5 and the engineering pile 4.

[0085] The prestress of the steel strands of the fish-belly beam 9: According to various working conditions of the foundation pit excavation, calculate the magnitudes of the earth pressure and water pressure acting on the position of the foundation pit side wall. Based on the stress mechanism of the fish-belly beam, then calculate the number of prestressed steel strands and the tension value of a single steel strand.

[0086] Prestress magnitude:

[0087] Required number of steel strands:

[0088] Wherein: P—the tensile force of the steel strand;

[0089] q—the design value of the horizontal load of the fish-belly beam support system;

[0090] L—the net spacing of the fish-belly beam connection part;

[0091] a—the included angle between the steel strand and the upper chord beam;

[0092] n—the required number of steel strands;

[0093] F—the design value of the tensile bearing capacity of a single steel strand.

[0094] Subsequent foundation pit monitoring is also required. Foundation pit monitoring refers to the monitoring of the vertical displacement, settlement, groundwater level, lateral deformation of the soil mass (inclinometer), vertical (horizontal) displacement of the top of the secant pile, vertical (horizontal) displacement of the wall top, axial force of the fish-belly beam support (stress gauge), etc. during the excavation and the construction of the pier foundation. The monitoring frequency is as follows in the table:

[0095]

[0096]

[0097] This cofferdam structure and construction method near the road in water, by setting multiple secant piles 6, internal support mechanisms, first retaining mechanisms, second retaining mechanisms and third retaining mechanisms; by setting different internal support structures and retaining structures respectively under various working conditions such as near the road and near the water, it adapts to complex environments, has good structural stability, large excavation space, and ensures construction safety.

[0098] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. An underwater cofferdam structure near a highway, characterized in that: It comprises a plurality of engaging piles (6), an inner supporting mechanism, a first supporting mechanism, a second supporting mechanism and a third supporting mechanism; A foundation pit is arranged on one side of a highway (1), an island (3) is arranged on the foundation pit, a plurality of interlocking piles (6) on the island (3) form a square cofferdam structure, a cap (5) is arranged inside the square cofferdam structure, and a plurality of engineering piles (4) are arranged on the cap (5); The inner support mechanism is arranged at the inner four corners of the square cofferdam structure; The first retaining mechanism is arranged on a side of the square cofferdam structure close to the highway (1); The second retaining mechanism is arranged on two side edges of the square cofferdam structure perpendicular to the highway (1); The third supporting mechanism is arranged on the water side of the square cofferdam structure.

2. The underwater cofferdam structure near the highway according to claim 1, characterized in that: The interlocking piles (6) include a plurality of reinforced concrete piles (6-1) and a plurality of plain concrete piles (6-2), wherein the plurality of reinforced concrete piles (6-1) and the plurality of plain concrete piles (6-2) are alternately connected and arranged, and a top pressure beam (10) is arranged on the upper part; A square cofferdam structure composed of a plurality of interlocking piles (6) is connected to six anchor cables (7) on one side close to the highway (1); A square cofferdam structure composed of a plurality of interlocking piles (6) is connected to five anchor cables (7) on both sides perpendicular to the highway (1).

3. The underwater cofferdam structure near the highway according to claim 1, characterized in that: The inner support mechanism comprises an angle brace (8) and a fish belly beam (9); the angle brace (8) is connected at a right angle to a square cofferdam structure formed by the plurality of interlocking piles (6); the fish belly beam (9) is connected to four walls of the square cofferdam structure; the fish belly beam (9) comprises a first fish belly beam (9-1) and a second fish belly beam (9-2), the first fish belly beam (9-1) being located above the second fish belly beam (9-2); the first fish belly beam (9-1) and the second fish belly beam (9-2) are connected with column piles (16).

4. The underwater cofferdam structure near the highway according to claim 1, characterized in that: The first support mechanism comprises a stopper (17), and the stopper (17) is connected to a side of the engagement pile (6) close to the road (1).

5. The underwater cofferdam structure near the highway according to claim 4, characterized in that: The second support mechanism comprises backfill soil (13), anchor rods (14) and concrete facing (15); the backfill soil (13) is arranged on the back side of the interlocking pile (6), the anchor rods (14) are inserted inside, and the concrete facing (15) is arranged outside.

6. The underwater cofferdam structure near the highway according to claim 2, characterized in that: The third support mechanism comprises a buttress-type flood control wall (18), which is arranged on the water-facing side of a square cofferdam structure composed of a plurality of interlocking piles (6) and is located above the capping beam (10).

7. The underwater cofferdam structure near the highway according to claim 5, characterized in that: A baffle (12) is provided on one side of the baffle block (17) and the backfill soil (13), and a stacked stone (11) is provided on the other side of the baffle (12).

8. A method for constructing an underwater cofferdam structure near a highway, characterized in that: The following steps are involved: Step 1: island construction; The middle part of the river within the scope of the foundation pit construction is filled with mountain soil and cave slag, and the filling range is 5.0m outside the edge of the foundation pit, and the slope is protected by pouring block stones or fine stone concrete; then conduct on-site surveys before building the island, check the on-site hydrogeological conditions, select and prepare clay soil materials; then measure and lay out according to the drawings and cofferdam design, insert benchmarks, and determine the location of the cofferdam; then mechanical riprap follows the order of "near first, then far, first point, then line, first shallow water area, then deep water area", step by step, and rip in layers; then build the soil and compact it. When filling clay soil on the cofferdam platform, pay attention to filling and compacting in layers, and fill the island surface with clay soil to create conditions for pile foundation construction; Step 2: Construction of interlocking piles; First, the plain concrete piles (6-2) are constructed, and then the reinforced concrete piles (6-1) are constructed; a plurality of reinforced concrete piles (6-1) and a plurality of plain concrete piles (6-2) are alternately connected and arranged to form a square cofferdam structure; Step 3: Construction of retaining structure; A block (17) is arranged on one side of a square cofferdam structure composed of a plurality of interlocking piles (6) close to the highway (1), a baffle (12) is arranged outside the block (17), and after the construction of the baffle (12) is completed, three anchor cables (7) are promptly installed from top to bottom; Backfill soil (13) is arranged perpendicularly on both sides of the highway (1) in a square cofferdam structure composed of a plurality of interlocking piles (6), anchor rods (14) are inserted into the backfill soil (13), and a concrete protective surface (15) is arranged on the outside, and then a baffle (12) is arranged on the outside of the backfill soil (13). After the construction of the baffle (12) is completed, two anchor cables (7) are promptly driven from top to bottom; A buttress-type flood control wall (18) is arranged on the water-facing side of a square cofferdam structure formed by a plurality of interlocking piles (6); Step 4: Install the inner support mechanism and set the anchor cable while excavating; First, the first anchor cable (7) is installed, and then the excavation is carried out downwards, and angle braces (8) are installed at the right angles of the square cofferdam structure, and the first fish belly beam (9-1) is installed on the four walls of the square cofferdam structure; Continue to dig downwards, set a second fish beam (9-2) on the four walls of the square cofferdam structure, and then drive a second anchor cable (7); Continue digging downwards and then install the third anchor cable (7); Continue to dig downwards to the right position, set the column pile (16), connect the upper end of the column pile (16) to the first fish belly beam (9-1) and the second fish belly beam (9-2), and then carry out the construction of the foundation (5) and the engineering pile (4).

Images