Polyurea anti-seepage gravity dam and construction method thereof

Abstract

The invention provides a polyurea anti-seepage gravity dam and a construction method thereof.The polyurea anti-seepage gravity dam comprises a dam body formed by filling low-strength homogeneous concrete, the dam body serves as a resistance main body of the gravity dam, and a foundation cushion layer and a reinforcing and anti-seepage structure are arranged between a dam foundation and bed rock of the dam body; a polyurea impermeable layer is integrally laid on the concrete surface of the dam face on the upstream side of the dam body. A plurality of vertical transverse joints are arranged in the dam body in the dam axis direction at intervals, a water stop structure is arranged at each vertical transverse joint of the dam body, and an expansion joint protruding towards the upstream is arranged at the upstream end of each vertical transverse joint. The polyurea impermeable layer comprises a permeable primer layer, a composite reinforcing layer and a sealing surface layer which are sequentially arranged outwards from the upstream dam face. The problems that in the construction and operation process of a traditional concrete gravity dam, cracks are prone to being generated, the overall structure is complex, and the construction quality of a water stop part is difficult to control are solved.

Description

Technical Field

[0001] The invention relates to the technical field of gravity dam water retaining engineering, and in particular to a polyurea anti-seepage gravity dam and a construction method thereof. Background Art

[0002] Traditional gravity dams primarily rely on the concrete structure of the dam body to form a retaining wall, leveraging the concrete's inherent anti-seepage properties. This places high demands on the material quality and construction process of the dam concrete. To enhance anti-seepage effectiveness, traditional gravity dams typically employ multiple waterstop structures (such as a combination of copper sheets and rubber waterstops), and the concrete is zoned according to the performance requirements of different parts of the dam body. This results in a complex overall structure, and quality control of the waterstop construction is also a challenge. Furthermore, during the concrete pouring process, the temperature rise caused by hydration heat can easily lead to cracks, weakening the dam's overall anti-seepage performance.

[0003] Based on the above situation, the present invention proposes a polyurea anti-seepage gravity dam and a construction method thereof, which can effectively solve the above problems. Summary of the Invention

[0004] In response to the shortcomings of the prior art, the first object of the present invention is to provide a polyurea anti-seepage gravity dam. This invention overcomes the problems of traditional concrete gravity dams, such as cracks that easily form during construction and operation, complex overall structure, and difficulty in controlling the quality of water-stop construction.

[0005] In a first aspect, the present invention provides a polyurea anti-seepage gravity dam, comprising a dam body formed by low-strength homogeneous concrete filling, the dam body serving as the main resistance body of the gravity dam, a foundation cushion layer and a reinforcement and anti-seepage structure being arranged between the dam foundation and the bedrock of the dam body, and a polyurea anti-seepage layer being paved on the entire concrete surface of the dam face on the upstream side of the dam body; a plurality of vertical transverse joints are arranged at intervals along the dam axis inside the dam body, a water-stop structure is arranged at each vertical transverse joint of the dam body, and an expansion joint protruding upstream is provided at the upstream end of each vertical transverse joint; the polyurea anti-seepage layer comprises a permeable primer layer, a composite reinforcement layer and a sealing surface layer arranged sequentially outward from the upstream dam face.

[0006] In one embodiment, a drainage system is provided inside the concrete on the upstream side of the dam body, in an area close to the upstream dam surface. The drainage system includes a plurality of vertical drainage holes and a plurality of horizontal drainage holes. The plurality of horizontal drainage holes are arranged at intervals in the height direction, and the plurality of vertical drainage holes are arranged at intervals in the horizontal direction, and the plurality of vertical drainage holes and the plurality of horizontal drainage holes are interconnected.

[0007] In one embodiment, a drainage gallery is provided inside the dam body, and the drainage system is connected to the drainage gallery via a connecting pipe.

[0008] In one embodiment, the water-stopping structure includes a spacer material filled in the vertical transverse seam.

[0009] In one embodiment, the water-stop structure includes a copper sheet water-stop and a rubber water-stop, and the copper sheet water-stop and the rubber water-stop are respectively buried in the vertical transverse seams corresponding to the upstream side and the downstream side of the drainage system.

[0010] In one embodiment, a V-shaped notch is reserved on the concrete surface of the dam face on the upstream side of the dam body at each vertical transverse joint, and the expansion joint protruding upstream is arranged in the V-shaped notch; the expansion joint includes a chloroprene rubber rod and an SR plastic filler, the chloroprene rubber rod is embedded in the bottom of the V-shaped notch, and the SR plastic filler fills the remaining space of the V-shaped notch, and forms a bulge on the surface protruding from the dam surface.

[0011] In one embodiment, a composite anti-seepage layer is added within a preset width range on the surface of the bulge and on both sides of the vertical transverse seam, and the polyurea anti-seepage layer covers the surface of the composite anti-seepage layer.

[0012] In one embodiment, a plurality of anchor pits are provided on the bedrock of the dam foundation portion corresponding to the vertical transverse joints, and the expansion joints and water-stopping structures are vertically extended downward and fixed in the corresponding anchor pits.

[0013] In one embodiment, the composite reinforcement layer is formed by spraying a single-component polyurea material, with polyester mesh cloth embedded inside, and the total thickness of the composite reinforcement layer is 2.0-2.5 mm; the sealing surface layer is formed by a two-component polyurea material with a thickness of 1.0-1.5 mm.

[0014] In a second aspect, a second object of the present invention is to provide a construction method of a polyurea anti-seepage gravity dam using any one of the above-mentioned methods, the construction method comprising the following steps:

[0015] S1. Carry out gravity dam foundation excavation and foundation defect treatment;

[0016] S2. Construct the foundation cushion of the gravity dam riverbed section and complete the consolidation grouting of the riverbed section;

[0017] S3. Construct low-strength homogeneous concrete for the gravity dam according to the dam body partitions, all the way to the dam crest. During the concrete construction of the dam body, pre-embed copper and rubber waterstops. After the concrete is poured above the drainage gallery, pre-embed vertical drainage holes between the copper and rubber waterstops, and provide a horizontal drainage hole in each construction joint.

[0018] S4. Carry out curtain grouting and construction of drainage holes in the dam foundation between the drainage gallery and the bedrock;

[0019] S5. Clean the V-shaped notch reserved for the vertical transverse joint and the concrete base surfaces on both sides. Apply a layer of asphalt latex to the area covered by the SR plastic filler. Fill the bottom of the V-shaped notch with a chloroprene rubber rod and then insert the SR plastic filler to form a bulge protruding from the dam surface.

[0020] S6. Polish the dam surface, clean and dry it, and then construct the polyurea anti-seepage layer; first apply a penetrating primer layer, then spray a single-component polyurea material, embed a polyester mesh cloth to form a composite reinforcement layer, and finally apply a two-component polyurea material to form a sealing surface layer.

[0021] The beneficial effects of the polyurea anti-seepage gravity dam and the construction method thereof provided by the present invention are:

[0022] The most difficult problem to control during concrete gravity dam construction is cracking, primarily caused by the heat of hydration during concrete pouring. The polyurea anti-seepage gravity dam provided by this invention overcomes the problems of traditional concrete gravity dams, such as the susceptibility to cracking during construction and operation, the complex overall structure, and the difficulty in controlling the quality of the waterstop construction.

[0023] In this invention, the dam body's primary function is to provide resistance, while the anti-seepage function is achieved by an external polyurea anti-seepage layer. Therefore, special crack control measures are not required for the dam concrete. Compared with conventional gravity dams (including roller-compacted concrete dams), the concrete block pouring size can be significantly increased, simplifying temperature control measures and crack control processes. This invention uses low-strength homogeneous concrete as the dam body fill material, which reduces the material quality requirements of the concrete, reduces construction costs and difficulty, and has strong adaptability, making it particularly suitable for areas with limited resources or complex construction conditions.

[0024] The present invention reserves V-shaped notches at each vertical transverse joint on the concrete surface on the upstream side of the dam body, and provides expansion joints protruding upstream, which cooperate with the polyurea anti-seepage layer covering structure to achieve effective sealing of the gap area, meet the deformation requirements such as opening, compression and dislocation of the transverse joints during the operation of the dam, and ensure the continuity and reliability of anti-seepage.

[0025] The present invention adopts the anti-seepage idea of ​​blocking in front and draining in the back, and constructs a multiple protection system composed of a polyurea anti-seepage layer, a drainage system and a water-stop structure: the first layer is the polyurea anti-seepage layer, which effectively seals the dam surface and structural joints; the second layer is the copper sheet water-stop set at the vertical transverse joints, which further improves the anti-seepage effect of the vertical transverse joints; the third layer is the drainage system set inside the dam body, which diverts the water that may seep in to the drainage corridor, reducing the erosion effect of the seepage on the dam body; the fourth layer is the rubber water-stop set at the vertical transverse joints, which further blocks the seepage path and ensures the dryness of the dam body.

[0026] In extreme cases, even if the expansion joint or copper sheet waterstop fails or the transverse joint deformation is too large, the rubber waterstop can still continue to play an anti-seepage role as the end line of defense by blocking the drainage system, ensuring system safety redundancy and improving the reliability and durability of project operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0028] Figure 1 An upstream vertical view of a polyurea anti-seepage gravity dam provided by an embodiment of the present invention;

[0029] Figure 2 A cross-sectional view of a polyurea anti-seepage gravity dam provided by an embodiment of the present invention;

[0030] Figure 3 A cross-sectional view of a vertical transverse seam of a polyurea anti-seepage gravity dam provided by an embodiment of the present invention;

[0031] Figure 4 A schematic structural diagram of a polyurea anti-seepage layer and an expansion joint provided in an embodiment of the present invention;

[0032] Figure 5 A schematic structural diagram of multiple anchor pits in a polyurea anti-seepage gravity dam provided by an embodiment of the present invention.

[0033] Figure numerals: 1. Dam foundation; 2. Gravity dam; 3. Vertical transverse joint; 4. Anchor pit; 5. Dam body; 6. Foundation cushion; 7. Drainage gallery; 8. Curtain grouting; 9. Dam foundation drainage hole; 10. Polyurea anti-seepage layer; 11. Horizontal drainage long hole; 12. Expansion joint; 13. Copper sheet water stop; 14. Rubber water stop; 15. Vertical drainage long hole; 16. Connecting pipe; 17. Expansion joint anchor pit; 18. Copper sheet water stop anchor pit; 19. Rubber water stop anchor pit; 20. Chloroprene rubber rod; 21. SR plastic filler; 22. Composite reinforcement layer; 23. Sealing surface layer; 24. Spacer material; 25. Composite anti-seepage layer. DETAILED DESCRIPTION

[0034] To help those skilled in the art better understand the technical solutions of the present invention, preferred embodiments of the present invention are described below in conjunction with specific examples. However, it should be understood that the drawings are for illustrative purposes only and are not to be construed as limiting the present invention. To better illustrate the present embodiments, certain components in the drawings may be omitted, enlarged, or reduced, and do not represent the dimensions of actual products. It is understandable that certain well-known structures and their descriptions may be omitted from the drawings. The positional relationships depicted in the drawings are for illustrative purposes only and are not to be construed as limiting the present invention.

[0035] The present invention will be further described below with reference to the accompanying drawings and examples, but they are not intended to limit the present invention.

[0036] like Figures 1 to 5 As shown, a polyurea anti-seepage gravity dam includes a dam body 5 formed by low-strength homogeneous concrete filling, the dam body 5 serving as the main resistance body of the gravity dam 2, a foundation cushion layer 6 and a reinforcement and anti-seepage structure are arranged between the dam foundation 1 of the dam body 5 and the bedrock, and a polyurea anti-seepage layer 10 is paved on the entire concrete surface of the dam face on the upstream side of the dam body 5; a plurality of vertical transverse joints 3 are arranged at intervals along the dam axis inside the dam body 5. In this embodiment, a vertical transverse joint 3 is arranged every 15 to 20 meters, a water-stop structure is provided at each vertical transverse joint 3 of the dam body 5, and an expansion joint 12 protruding upstream is provided at the upstream end of each vertical transverse joint 3; the polyurea anti-seepage layer 10 includes a permeable primer layer, a composite reinforcement layer 22 and a sealing surface layer 23 arranged in sequence from the upstream dam face to the outside.

[0037] This invention separates the dam's structural load-bearing function from its anti-seepage function. Anti-seepage performance is achieved through a polyurea anti-seepage layer applied across the upstream dam surface, effectively reducing reliance on the concrete's inherent anti-seepage properties. Furthermore, the polyurea anti-seepage layer provides a complete seal, effectively preventing water seepage from the dam surface and structural joints.

[0038] In this embodiment, the cross-section of the dam body is triangular. The concrete grade used for the foundation cushion layer 6 is no less than C20, with an anti-seepage grade determined based on the water head required for anti-seepage, and no less than W8. The concrete strength grade of the dam body 5 is no higher than C15, with no anti-seepage grade requirement. The dam body 5 can be constructed of normal concrete, roller-compacted concrete, or buried rock concrete, with the corresponding foundation cushion layer 6 constructed of normal concrete, modified concrete, or normal concrete, respectively.

[0039] The dam body 5 is provided with a drainage system inside the concrete on the upstream side, in an area close to the upstream dam surface.

[0040] The drainage system includes multiple vertical drainage holes 15 and multiple horizontal drainage holes 11. The multiple horizontal drainage holes 11 are arranged at intervals in the height direction. Specifically, during the construction of the dam body 5, a horizontal drainage hole 11 is set in each construction joint in the dam body 5, and the multiple vertical drainage holes 15 are arranged at intervals in the horizontal direction. The multiple horizontal drainage holes 11 and the multiple vertical drainage holes 15 are in the same plane, and the multiple vertical drainage holes 15 and the multiple horizontal drainage holes 11 are connected to each other.

[0041] In this embodiment, the vertical drainage holes 15 and the horizontal drainage holes 11 are both provided with geotextile-wrapped geotextile drainage blind pipes. The diameter of the vertical drainage holes 15 is 20 cm, and the diameter of the horizontal drainage holes is 10 cm.

[0042] A drainage gallery 7 is provided inside the dam body 5 , and the drainage system is connected to the drainage gallery 7 via a connecting pipe 16 .

[0043] The water-stop structure includes a spacer material 24 filled in the vertical transverse seam 3. Specifically, the spacer material 24 is made of asphalt pine wood board or closed-cell foam board.

[0044] The water-stop structure includes a copper sheet water-stop 13 and a rubber water-stop 14 , and the copper sheet water-stop 13 and the rubber water-stop 14 are respectively buried in the vertical transverse seams 3 corresponding to the upstream and downstream sides of the drainage system.

[0045] A V-shaped notch is reserved on the concrete surface of the dam surface on the upstream side of the dam body 5 at each vertical transverse joint 3, and the expansion joint 12 protruding upstream is arranged in the V-shaped notch; the expansion joint 12 includes a chloroprene rubber rod 20 and an SR plastic filler 21, the chloroprene rubber rod 20 is embedded in the bottom of the V-shaped notch, and the SR plastic filler 21 fills the remaining space of the V-shaped notch and forms a bulge protruding from the dam surface on the surface.

[0046] Specifically, the depth and width of the V-notch should be controlled within 5 cm, and the bulge area should be controlled within 150 cm. 2 Furthermore, a composite anti-seepage layer 25 is added within 20 cm on the bulge surface and on both sides of the vertical transverse seam 3.

[0047] A plurality of anchor pits 4 are provided on the bedrock at the location of the dam foundation 1 corresponding to the vertical transverse joints 3. The expansion joints 12 and water-stop structures are vertically extended downward and fixed in the corresponding anchor pits 4. Specifically, an expansion joint anchor pit 17, a copper sheet water-stop anchor pit 18, and a rubber water-stop anchor pit 19 are provided in the bedrock below the location of the dam foundation 1. The expansion joint 12, copper sheet water-stop 13, and rubber water-stop 14 are respectively extended into the expansion joint anchor pit 17, the copper sheet water-stop anchor pit 18, and the rubber water-stop anchor pit 19, and slightly expansive fine stone concrete is poured in the gaps.

[0048] A joint typically exists at the junction of the concrete dam body and the bedrock. This gap is a structural weakness. If improperly addressed, it can easily lead to leakage during operation, causing water to seep in and migrate downstream. To address this issue, the present invention incorporates multiple anchor pits at this joint. The expansion joint 12 and water-stop structure extend vertically downward and are anchored in corresponding anchor pits 4, enhancing the anti-seepage and overall stability of the joint. Furthermore, micro-expansive fine-stone concrete is poured into this gap to fill the void and increase its density, further enhancing the anti-seepage effect.

[0049] In this embodiment, a penetrating primer layer is applied to the polished and cleaned upstream dam concrete surface, with a thickness of 0.2-0.3 mm. The composite reinforcement layer 22 is sprayed with a single-component polyurea material, embedded with a hexagonal polyester mesh with a tensile strength of ≥50 kN / m. The mesh width is 30 ± 2 cm, and the total thickness of the composite reinforcement layer 22 is 2.0-2.5 mm. The sealing surface layer 23 is formed from a two-component polyurea material with a thickness of 1.0-1.5 mm.

[0050] The reinforcement and anti-seepage structure consists of three parts: consolidation grouting, curtain grouting 8, and dam foundation drain holes 9. Consolidation grouting is determined based on the bedrock conditions and the stress of the dam foundation 1. It is generally performed across the entire foundation surface of the gravity dam, with a depth of 5-8 meters. Curtain grouting 8 is located upstream of the drainage gallery 7, with a depth determined by calculation and specifications based on anti-seepage standards. Dam foundation drain holes 9 are located downstream of the drainage gallery 7, with a depth generally half that of the upstream curtain.

[0051] The present invention also provides a construction method for a polyurea anti-seepage gravity dam, comprising the following steps:

[0052] S1. Carry out foundation excavation and foundation defect treatment of gravity dam 2;

[0053] S2. Construct the foundation cushion layer 6 of the riverbed section of the gravity dam 2 and complete the consolidation grouting of the riverbed section;

[0054] S3. Construction of low-strength homogeneous concrete for the gravity dam (2) is carried out according to the dam body (5) zones, extending to the dam crest. Consolidation grouting of the dam foundation (1) on both sides is planned and constructed following the rise in fill elevation of the dam body (5). The height of each concrete layer is controlled based on achievable strength and construction safety.

[0055] Furthermore, during the concrete construction of the dam body 5, a copper sheet water stop 13 and a rubber water stop 14 are pre-embedded. After the concrete is poured above the drainage gallery 7, a vertical drainage long hole 15 is pre-embedded between the copper sheet water stop 13 and the rubber water stop 14, and a horizontal drainage long hole 11 is set in each layer of construction joint.

[0056] The horizontal drainage holes are required to be set along the horizontal construction joints. Specifically, after each layer of concrete is poured and before initial setting, a 10cm steel pipe is used to press and cover to form a semicircular reserved groove.

[0057] During the construction process, except for controlling the pouring temperature according to the specifications, no other temperature control measures are required. If cracks appear on the dam surface during construction, grouting of the foundation cushion layer will be carried out;

[0058] S4, curtain grouting 8 and construction of drainage holes 9 in the dam foundation between the drainage gallery 7 and the bedrock;

[0059] S5. Clean the V-shaped notch reserved for the vertical transverse joint 3 and the concrete base surfaces on both sides. Apply a layer of asphalt latex to the area covered by the SR plastic filler 21. Fill the bottom of the V-shaped notch with a chloroprene rubber rod 20 and then insert the SR plastic filler 21 to form a bulge protruding from the dam surface.

[0060] Furthermore, the expansion joint 12 is constructed from bottom to top. After each meter of height is completed, the composite anti-seepage layer 25 is immediately laid. The composite anti-seepage layer 25 is laid over the outer surface of the bulge and a 20 cm area on either side of the vertical transverse seam 3. The composite anti-seepage layer 25 in this area is constructed using a spray-coated single-component polyurea material with an embedded hexagonal polyester mesh to form a composite reinforcement layer. The thickness is 2.0-2.5 mm.

[0061] S6. Polish the dam surface, clean and dry it, and then construct the polyurea anti-seepage layer 10; first apply a penetrating primer layer with a thickness of 0.2-0.3 mm, then spray a single-component polyurea material with an embedded hexagonal polyester mesh to form a composite reinforcement layer 22 with a thickness of 2.0-2.5 mm, and finally apply a two-component polyurea material to form a sealing surface layer 23 with a thickness of 1.0-1.5 mm.

[0062] According to the description and drawings of the present invention, those skilled in the art can easily manufacture or use the polyurea anti-seepage gravity dam and the construction method thereof of the present invention, and can produce the positive effects described in the present invention.

[0063] Unless otherwise specified, in the present invention, if there are terms such as "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", and "circumferential" indicating orientation or positional relationships, they are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the terms describing the orientation or positional relationship in the present invention are only used for illustrative purposes and cannot be understood as limiting the present invention. For those skilled in the art, the specific meanings of the above terms can be understood in conjunction with the accompanying drawings and according to specific circumstances.

[0064] Unless otherwise specified or limited, the terms "disposed," "connected," and "connected" in this disclosure should be interpreted broadly. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to direct connections, indirect connections through an intermediary, or internal connections between two components. Those skilled in the art will understand the specific meanings of these terms in this disclosure based on the specific circumstances.

[0065] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification or equivalent change made to the above embodiment based on the technical essence of the present invention shall fall within the scope of protection of the present invention.

Claims

1. A polyurea anti-seepage gravity dam, characterized by: The invention comprises a dam body formed by low-strength homogeneous concrete filling, which serves as the main resistance body of the gravity dam. A foundation cushion layer and a reinforcement and anti-seepage structure are arranged between the dam foundation and the bedrock of the dam body. The entire concrete surface of the dam face on the upstream side of the dam body is paved with a polyurea anti-seepage layer. A plurality of vertical transverse joints are arranged at intervals along the dam axis inside the dam body. A water-stop structure is arranged at each vertical transverse joint of the dam body, and an expansion joint protruding upstream is provided at the upstream end of each vertical transverse joint. The polyurea anti-seepage layer comprises a permeable primer layer, a composite reinforcement layer and a sealing surface layer arranged sequentially from the upstream dam face to the outside.

2. The polyurea anti-seepage gravity dam according to claim 1, characterized in that: The dam body is provided with a drainage system inside the concrete on the upstream side, in an area close to the upstream dam surface. The drainage system includes a plurality of vertical drainage holes and a plurality of horizontal drainage holes. The plurality of horizontal drainage holes are arranged at intervals in the height direction, and the plurality of vertical drainage holes are arranged at intervals in the horizontal direction, and the plurality of vertical drainage holes and the plurality of horizontal drainage holes are connected to each other.

3. The polyurea anti-seepage gravity dam according to claim 2, characterized in that: A drainage gallery is provided inside the dam body, and the drainage system is connected with the drainage gallery through a connecting pipe.

4. The polyurea anti-seepage gravity dam according to claim 1, characterized in that: The water-stopping structure includes a spacer material filled in the vertical transverse seam.

5. The polyurea anti-seepage gravity dam according to claim 2, characterized in that: The water-stop structure includes a copper sheet water-stop and a rubber water-stop, and the copper sheet water-stop and the rubber water-stop are respectively buried in the vertical transverse seams corresponding to the upstream side and the downstream side of the drainage system.

6. The polyurea anti-seepage gravity dam according to claim 1, characterized in that: A V-shaped notch is reserved at each vertical transverse joint on the concrete surface of the dam surface on the upstream side of the dam body, and the expansion joint protruding upstream is arranged in the V-shaped notch; the expansion joint includes a chloroprene rubber rod and an SR plastic filler, the chloroprene rubber rod is embedded in the bottom of the V-shaped notch, and the SR plastic filler fills the remaining space of the V-shaped notch, and forms a bulge on the surface protruding from the dam surface.

7. The polyurea anti-seepage gravity dam according to claim 6, characterized in that: A composite anti-seepage layer is added within a preset width range on the surface of the bulge and on both sides of the vertical transverse seam, and the polyurea anti-seepage layer covers the surface of the composite anti-seepage layer.

8. The polyurea anti-seepage gravity dam according to claim 1, characterized in that: A plurality of anchoring pits are provided on the bedrock of the dam foundation portion corresponding to the vertical transverse joints, and the expansion joints and the water-stopping structures are vertically extended downward and fixed in the corresponding anchoring pits.

9. The polyurea anti-seepage gravity dam according to claim 1, characterized in that: The composite reinforcement layer is formed by spraying a single-component polyurea material, and is embedded with a polyester mesh cloth. The total thickness of the composite reinforcement layer is 2.0-2.5 mm. The sealing surface layer is formed by a two-component polyurea material and has a thickness of 1.0-1.5 mm.

10. A construction method for a polyurea anti-seepage gravity dam according to any one of claims 1 to 9, characterized in that: The construction method comprises the following steps: S1. Carry out gravity dam foundation excavation and foundation defect treatment; S2. Construct the foundation cushion of the gravity dam riverbed section and complete the consolidation grouting of the riverbed section; S3. Construct low-strength homogeneous concrete for the gravity dam according to the dam body partitions, all the way to the dam crest. During the concrete construction of the dam body, pre-embed copper and rubber waterstops. After the concrete is poured above the drainage gallery, pre-embed vertical drainage holes between the copper and rubber waterstops, and provide a horizontal drainage hole in each construction joint. S4. Carry out curtain grouting and construction of drainage holes in the dam foundation between the drainage gallery and the bedrock; S5. Clean the V-shaped notch reserved for the vertical transverse joint and the concrete base surfaces on both sides. Apply a layer of asphalt latex to the area covered by the SR plastic filler. Fill the bottom of the V-shaped notch with a chloroprene rubber rod and then insert the SR plastic filler to form a bulge protruding from the dam surface. S6. Polish the dam surface, clean and dry it, and then construct the polyurea anti-seepage layer; first apply a penetrating primer layer, then spray a single-component polyurea material, embed a polyester mesh cloth to form a composite reinforcement layer, and finally apply a two-component polyurea material to form a sealing surface layer.

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