A method for treating transverse joint leakage of a concrete gravity dam

Abstract

This invention proposes a method for treating seepage in transverse joints of concrete gravity dams, belonging to the field of water conservancy and hydropower engineering. The method includes the following steps: First, a first composite seepage interception layer is constructed at the transverse joint on the upstream dam face. This first composite seepage interception layer consists of a plastic water-stopping material embedded in the U-shaped groove of the transverse joint and a polyurea elastic coating covering the dam face and the transverse joint. Second, a second elastic water-stopping seepage barrier is constructed between the two water-stops at the dam crest. This second elastic water-stopping seepage barrier consists of a water-soluble polyurethane grout solidified and injected into boreholes along the joint. Third, a third drainage channel is constructed downstream of the second water-stop. This third drainage channel consists of drainage holes along the joint that penetrate the transverse joint to the lower gallery. This invention adopts a three-in-one technical concept of "interception-blocking-drainage." The upstream dam face intercepts and prevents reservoir water from directly entering the joint surface; the middle water-stop seals the seepage channels inside the transverse joint; and the downstream drainage holes drain residual seepage from the transverse joint. These three lines of defense work together to form a complete and reliable seepage prevention system.

Description

Technical Field

[0001] This invention relates to the field of water conservancy and hydropower engineering technology, and in particular to a method for treating seepage in transverse joints of concrete gravity dams. Background Technology

[0002] To accommodate uneven settlement and temperature changes in the foundation, concrete gravity dams are equipped with permanent vertical transverse joints perpendicular to the dam axis. These joints typically contain multiple water-stop plates (such as copper water-stop plates) to form a seepage prevention system. However, due to factors such as aging of the water-stopping materials, construction defects, harmful uneven settlement of the dam foundation, and the repeated opening and closing deformation of the transverse joints under cyclic loads during long-term operation, the transverse joint water-stopping system is prone to localized failure. This can lead to reservoir water seeping along the joints into the dam gallery or downstream of the dam. Long-term or excessive seepage not only affects the dam's appearance but can also cause problems such as concrete erosion, steel reinforcement corrosion, and increased seepage pressure, which can seriously endanger the structural safety and durability of the dam.

[0003] Currently, conventional methods for treating transverse joint leakage in concrete gravity dams mainly fall into two categories: one is the shallow sealing method on the upstream dam face, such as chiseling grooves at the transverse joints on the dam face and filling them with flexible water-stopping materials or applying a waterproof coating; the other is the dam crest drilling and grouting method, which involves drilling holes along the transverse joints on the dam crest and injecting cement grout or chemical grout into the joints. However, these conventional methods all employ only a single treatment measure, resulting in less than ideal results. For example, the shallow sealing method on the upstream dam face only acts on the surface layer of a certain width of the joint. If the deep water-stopping fails, the reservoir water can bypass the surface sealing material and continue to leak. Although dam crest drilling and grouting can fill the joint surface, a single grout body is difficult to adapt to the periodic opening and closing deformation of the transverse joints under the influence of reservoir water level changes and temperature cycles. The grout body is easily torn or crushed, leading to secondary leakage. It is evident that the existing treatment methods lack a systematic and comprehensive approach, failing to address the problem of transverse joint leakage from a systematic perspective of "source interception-seepage prevention-drainage," resulting in residual leakage or insufficient durability of the treatment effect after treatment. Summary of the Invention

[0004] In view of this, the present invention proposes a method for treating transverse joint leakage in concrete gravity dams, which addresses the problem that existing transverse joint leakage treatment methods are too simplistic and lack a systematic and comprehensive treatment concept.

[0005] The technical solution of this invention is implemented as follows: This invention provides a method for treating seepage in transverse joints of a concrete gravity dam, comprising the following steps: S1, constructing a first composite seepage intercepting layer at the transverse joint on the upstream dam face, the first composite seepage intercepting layer being composed of SR plastic water-stopping material embedded in the U-shaped groove of the transverse joint and a polyurea elastic coating covering the dam face and the transverse joint; S2, constructing a second elastic water-stopping seepage barrier between the two water-stops in the transverse joint, the second elastic water-stopping seepage barrier being composed of a water-soluble polyurethane grout solidified body injected into a borehole across the joint; S3, constructing a third drainage channel downstream of the second water-stop, the third drainage channel being composed of a drainage hole across the joint extending from the transverse joint to the lower gallery.

[0006] Based on the above technical solutions, the preferred timing for constructing the first composite cutoff layer is, according to dam safety monitoring data, when the transverse joint opening reaches 65%-75% of its annual maximum opening.

[0007] Based on the above technical solutions, preferably, when constructing the first composite cutoff layer, the calculation formula and value of the U-shaped groove width are as follows: Groove width calculation: B1≥k(b'-b) / L%; B2≥k(b-b'') / L'%; Groove width value: B = max(B1, B2), where B is the U-shaped groove width; B1 is the groove width calculated based on elastic tension; B2 is the groove width calculated based on elastic compression; b is the actual width of the transverse joint during treatment; b' is the width of the transverse joint at maximum deformation; b'' is the width of the transverse joint at minimum deformation; the units of the above parameters are all cm; the long-term maximum elastic tensile rate of polyurea is L%; the long-term maximum elastic compression rate of polyurea is L'%; k is the safety factor.

[0008] Based on the above technical solutions, preferably, the borehole inclination of the drilled hole is less than 0.1%, and the hole diameter is not less than 150mm; the drilling position is on the surface of the transverse seam to ensure that the drill hole penetrates and exposes the transverse seam.

[0009] A further preferred method for constructing the second elastic water-stopping and seepage-preventing layer includes the following steps: S21, based on the actual width b of the transverse joint obtained from core drilling and the transverse joint area S between the two water-stopping layers in the grouting section, combined with the transverse joint porosity α, the theoretical grouting injection volume Q is calculated. 理 S22, Graded pressurized grouting is carried out using pure pressure grouting method; S23, The actual injected volume Q is measured in real time during the grouting process. 实 When Q 实 Reaching Q 理 When the injection rate is less than 0.5 L / min at this pressure level, and the injection rate is 90%~100%, grouting should be stopped after stabilizing the pressure for 30 minutes; S24, if Q is at the highest pressure of 0.3 MPa, 实 Much smaller than Q 理If 90% of the seal is intact, it is considered a minor seam and requires re-filling with a low-viscosity material; if Q... 实 Far exceeding Q 理 If the grout flow rate is 110%, it is determined that there is a grout leakage channel, and grouting should be suspended and measures such as flow restriction, pressure reduction, waiting for curing, and leak plugging should be taken.

[0010] More preferably, in step S21, according to formula Q 理 = πr²L + αSb calculates the theoretical grouting injection volume, where r is the borehole radius, L is the grouting section length, b is the actual width of the transverse joint (all parameters are in cm); S is the transverse joint area between the two waterstops in the grouting section (unit: cm²). 2 α represents the porosity of the transverse seam.

[0011] More preferably, in step S21, the porosity α of the transverse seam ranges from 0.5 to 0.8, and this parameter is corrected by inversion based on the permeability data of the previous exploration borehole water pressure test.

[0012] More preferably, in step S21, the grouting adopts a segmented plugging and bottom-up process, and in different grouting sections, the transverse joint width b parameter in the theoretical injection volume formula is dynamically adjusted according to the depth of the section, the core sample of the cross joint hole and the stress condition.

[0013] More preferably, in step S22, the grouting pressure is applied in increments of 0.1 MPa, 0.2 MPa, and 0.3 MPa, with each pressure level stabilizing for at least 10 minutes.

[0014] Based on the above technical solutions, the preferred method is to drill a third drainage channel vertically from the top of the dam to the corresponding gallery above the lower part of the dam body, so that the seepage water from the transverse joints can be diverted to the drainage ditch of the gallery through the drilled hole.

[0015] The method for treating transverse joint leakage in concrete gravity dams according to the present invention has the following advantages over the prior art: (1) The present invention adopts the three-in-one technical concept of “interception-blocking-drainage”. The upstream dam surface intercepts and blocks the reservoir water from directly entering the joint surface, the middle water-stopping and seepage-blocking seals the internal seepage channels of the horizontal joint, and the downstream drainage hole drains the residual seepage water of the horizontal joint. The three lines of defense work together to form a complete and reliable seepage prevention system, which solves the problem of poor treatment effect of single method.

[0016] (2) The upstream surface of the present invention adopts a composite structure of SR plastic water-stop material combined with polyurea elastic coating. SR material has the property of swelling when exposed to water, and polyurea coating has a large elongation at break. The two work together to adapt to the periodic opening and closing deformation of the transverse joint. The middle part adopts water-soluble polyurethane grouting, and its solidified body has good elasticity, avoiding the defect of conventional rigid grouting body being easily torn.

[0017] (3) The present invention ensures that the drilling accurately exposes the joint surface by drilling with large diameter and high precision; based on the theoretical injection volume calculation formula and graded pressure control, it realizes precise quantitative control of the grouting process, avoids material waste or insufficient grouting caused by blind grouting, and can detect abnormal situations such as cross-grouting in a timely manner.

[0018] (4) The present invention selects the window period when the opening of the transverse joint reaches 65%-75% of the maximum opening of the year, so that the SR material and polyurea coating are always in the best elastic stress state during the subsequent deformation of the transverse joint. This avoids the material being squeezed and damaged when the transverse joint is closed, and ensures that the material can be effectively stretched and sealed when the transverse joint is opened, which significantly improves the durability of the treatment effect. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the transverse seam treatment structure of the present invention; Figure 2 This is a schematic diagram of the dam body side section structure of the present invention.

[0021] In the diagram: 1. Upstream dam face; 2. Horizontal joint; 3. U-shaped groove; 4. SR plastic waterstop material; 5. Polyurea elastic coating; 6. First waterstop; 7. Second waterstop; 8. Seepage-blocking hole across the joint; 9. Water-soluble polyurethane solidified body; 10. Drainage hole across the joint; 11. Dam gallery; 12. Gallery drainage ditch. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0023] In the description of the embodiments of the present invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of the present invention based on the specific circumstances.

[0024] In the description of the embodiments of the present invention, it should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of 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, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of the present invention.

[0025] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0026] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0027] The following disclosure provides numerous different embodiments or examples for implementing various structures of the invention. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the invention. Furthermore, reference numerals and / or letters may be repeated in different examples. Such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. Additionally, examples of various specific processes and materials are provided in this invention; however, those skilled in the art will recognize the applicability of other processes and / or the use of other materials.

[0028] like Figure 1 As shown, combined with Figure 2The present invention provides a method for treating transverse joint leakage in a concrete gravity dam, comprising the following steps: S1, constructing a composite cutoff layer on the upstream dam face: First, based on long-term observation data from the dam safety monitoring system, the variation pattern of the transverse joint opening was analyzed to determine its annual maximum opening. Construction was carried out when the transverse joint opening reached approximately 70% of the annual maximum opening. At this point, the joint surface is in a semi-open state, which facilitates material filling and ensures that the material is not excessively compressed when the transverse joint closes subsequently. Furthermore, the material still has sufficient tensile allowance when the transverse joint further opens.

[0029] The specific construction process is as follows: (1) Base surface treatment: Mark the elevation and range of the area to be treated. Along the transverse joint 2, within a range of 8-10cm on both sides, use a handheld cutting machine and electric pick to remove the surface layer of the dam concrete, with a depth controlled at 3-5mm, to expose the fresh and dense concrete base. Remove the laitance, dust, oil stains and other attachments on the concrete surface, and repair local damage, voids and other defects with epoxy mortar. Manually chisel a U-shaped groove 3 along the transverse joint 2. According to the calculated groove width B, chisel a U-shaped groove with a width and depth of B along the transverse joint. The width and depth of the U-shaped groove are controlled at about 5cm. After the groove is opened, wash it clean with a high-pressure water gun and use a blowtorch to bake it so that the concrete base surface inside the groove and on both sides is fully dry.

[0030] (2) U-shaped groove filling: Apply a special primer (such as epoxy interface agent) evenly to the bottom of the dry U-shaped groove 3. After the primer is surface dry (about 30-60 minutes), roll the SR plastic waterstop material 4 into thin strips with a diameter slightly smaller than the groove width, and fill it into the U-shaped groove in layers. Each layer should be about 1-1.5cm thick. Use a special wooden mallet or stick to compact each layer to ensure that the material is tightly attached to the groove wall without any voids. After filling, make the surface of the material slightly protrude from the groove opening by about 2-3mm to form pre-compression stress. The SR plastic sealing material 4 used in this embodiment is a water-swellable plastic sealing material with organosilicon-modified non-vulcanized butyl rubber as the main agent. Its main performance indicators are: density 1.2-1.4 g / cm³, workability (25℃) 3-5 mm, heat resistance (80℃, 45° angle, 5h) no flow, low temperature resistance (-20℃, 2h) no brittleness, impermeability (1.5MPa water pressure, 24h) water impermeability, and water swelling rate not less than 200%. This material has excellent adhesion, durability and water swelling characteristics: when the horizontal joint is closed, the material is compressed to generate pre-stress; when the horizontal joint is opened, the material is stretched and expands in volume upon contact with water, which can further fill the open gap and achieve dynamic sealing.

[0031] (3) Application of interface agent: After the U-shaped groove is filled, the sanded concrete base surface on both sides of the horizontal joint is cleaned and dried again. Apply a special interface agent (such as polyurea primer), and the application area should be 2-3 cm larger than the coverage area of ​​the subsequent polyurea coating. The interface agent should be applied thinly and evenly, without omissions or accumulation. The base surface must not come into contact with dust, solvents or debris during the application process.

[0032] (4) Polyurea Elastic Coating Application: 1-4 hours after the interface agent has dried, begin applying the polyurea elastic coating 5. This embodiment uses a multi-layer application process: the first layer of polyurea is applied to a thickness of approximately 1mm, followed by the laying of a layer of reinforcing fabric (such as polyester nonwoven fabric), which is then compacted with a roller to ensure full saturation; the second layer of polyurea is applied to a thickness of approximately 1mm, covering and securing the reinforcing fabric; the third layer of polyurea is applied, adjusting the total thickness to approximately 5mm, and the surface is then smoothed. Each layer should be applied evenly, and the polyurea must not be contaminated by water, dust, or debris during the application process. The polyurea coating must not come into contact with water for 2 hours after application, and must be protected from external impacts for 72 hours. The polyurea elastic coating material used in this embodiment is a hand-scraped aromatic polyurea elastomer, whose main performance indicators are: 100% solid content, tensile strength ≥15MPa, elongation at break ≥450%, tear strength ≥60N / mm, adhesion (to concrete) ≥2.5MPa, no abnormalities in water resistance (23℃×7d), and good chemical corrosion resistance. The high elongation at break ensures that the coating can adapt to the periodic opening and closing deformation of transverse seams without cracking; the reinforcing base layer improves the tensile strength and puncture resistance of the coating.

[0033] S2, central joint waterproofing and seepage prevention structure: At the position between the first and second waterstops 6 and 7 corresponding to the transverse joint on the dam crest, a seepage-blocking hole 8 is drilled across the joint.

[0034] Specifically: (1) Drilling construction: Geological drilling rigs are used in conjunction with high-precision drilling tools. The drilling positioning is accurately laid out using a total station to ensure that the center of the borehole is aligned with the surface of the transverse joint. Anti-skewing measures are taken during the drilling process (such as adding a stabilizer, controlling drilling pressure and rotation speed). The final borehole skewing is controlled within 0.1%, and the borehole diameter is 150mm. The drilling depth is from the top of the dam to a certain depth below the first water-stop plate (it needs to penetrate the entire water-stop section). After the drilling is completed, high-pressure water is used to flush the debris in the hole, and a water pressure test is conducted to obtain the permeability data of the joint surface. The large-diameter (≥150mm) design has the following advantages: First, it is convenient for subsequent grouting plugs to be segmented and plugged; second, the area of ​​the joint surface exposed by the borehole is larger, which is conducive to the diffusion of grout; third, once the borehole deviates, there is still a certain probability that part of the joint surface will be exposed, which improves the success rate of riding the joint. High-precision borehole skewing control (<0.1%) ensures that the borehole is truly "riding" on the joint surface and avoids damage to the water-stop plates on both sides.

[0035] (2) Grouting Construction: A segmented, bottom-up, pure pressure grouting process is adopted. The length of each grouting segment is controlled to 3-5m according to the drilling depth. The grouting material is water-soluble polyurethane, which reacts chemically with water to form an elastic solid, characterized by high bonding strength, good permeability, and excellent elasticity, capable of adapting to subsequent deformation of the transverse joint. Precise quantitative control is employed during the grouting process.

[0036] S21, Theoretical Injection Volume Calculation: Based on the actual width b of the transverse joint obtained from core drilling (measured by core sample or observed by borehole television) and the transverse joint area S between the two waterstops in the grouting section (determined by the joint height revealed by the borehole and the length of the transverse joint), combined with the transverse joint porosity α, according to formula Q... 理 = πr²L + αSb Calculate the theoretical grouting injection volume. Where r is the borehole radius, L is the grouting section length, πr²L is the borehole volume, b is the actual width of the transverse joint (all parameters are in cm), and S is the transverse joint area between the two waterstops in the grouting section (unit: cm²). 2 α represents the transverse joint porosity, reflecting the influence of factors such as joint surface undulation and filling material on the actual irrigable space. The value range is determined by inversion correction based on the permeability data from previous exploration borehole pressure tests.

[0037] S22, graded pressurized grouting: Grouting is performed using a pure pressure grouting pump, with grouting pressure applied in stages of 0.1MPa, 0.2MPa, and 0.3MPa. After each pressure is reached, it should be stabilized for at least 10 minutes, and the injection rate should be observed. Graded pressurization facilitates the smooth diffusion of the grout and avoids sudden pressure increases that could cause cracking of the joint surface or grout loss.

[0038] S23, Real-time verification and completion criteria: During the grouting process, the actual injected volume Q is measured in real time using an electronic flow meter. 实 When Q 实 Reaching Q 理 When the injection rate is less than 0.5 L / min at this pressure level, the grouting of this section is stopped after stabilizing the pressure for 30 minutes.

[0039] S24, Abnormal Situation Handling: If Q is at the maximum pressure of 0.3MPa 实 Much smaller than Q 理 If 90% (or less than 50%) of the sealant is filled, it is considered to be due to fine lines or localized blockage, requiring re-injection with low-viscosity water-soluble polyurethane material to improve permeability; if Q 实 Far exceeding Q 理 If the grout flow rate is 110%, it is determined that there is a grout leakage channel (e.g., connected to adjacent transverse joints, drainage holes, or defective areas). Grouting should be suspended, the grout leakage path should be identified, and measures such as flow restriction, pressure reduction, waiting for setting, and leak sealing should be taken (e.g., pre-injecting cement grout to seal the large channel) before grouting can continue.

[0040] It is important to note that the transverse joint width parameter 'b' in the theoretical injection volume formula should be dynamically adjusted according to the depth, transverse joint tension, and stress conditions of different grouting sections. For example, the joint width may be smaller in deep sections due to the influence of ground stress, and the value of 'b' needs to be corrected in real time based on borehole television measurement results to ensure that the theoretical calculation matches the actual situation. After grouting is completed, the opening of the cross-joint seepage barrier hole 8 is sealed and protected with a steel cover plate to prevent foreign objects from falling in.

[0041] S3, Construction of downstream drainage channels: Downstream of the water-stopping system, below the second water-stop 7, at the transverse joint above the lower dam gallery 11, a drainage hole 10 is drilled. The drilling must have an inclination of less than 0.1% and a diameter of not less than 150mm to ensure precise alignment with the joint. The hole is drilled vertically from the dam crest to the top of the lower gallery 11, penetrating the transverse joint surface. After drilling, a permeable pipe can be installed inside the hole, or it can be used directly as a water diversion channel to guide any residual seepage water in the transverse joint to the drainage ditch 12 within the gallery, achieving organized drainage and reducing seepage pressure downstream of the transverse joint.

[0042] S4. After the method of this embodiment is applied, the treatment effect is verified in the following ways.

[0043] (1) Drilling and coring inspection: Drill inspection holes near the treated transverse seam. Coring inspection shows that the water-soluble polyurethane solidified body in the seam surface is densely filled and well bonded to the seam surface; the upstream SR material is tightly bonded to the polyurea coating, with no voids or cracks.

[0044] (2) Leakage monitoring: After treatment, continuous observation was conducted for 12 months. The original leakage points in the dam gallery were dry and without water. There was no open flow or only a small amount of moisture in the drainage holes on the downstream side of the transverse joint. The readings of the piezometer showed a significant decrease in seepage pressure.

[0045] (3) Deformation adaptability test: After a complete cycle of reservoir water level rise and fall and winter and summer temperature change, no new cracks were found on the surface of the polyurea coating, and no extrusion or hollowing was found in the SR material, indicating that the "interception-blockage-exhaustion" system has good deformation adaptability.

[0046] In another embodiment, when constructing the first composite cutoff layer, the calculation formula and value of the U-shaped groove width are as follows: Groove width calculation: B1≥k(b'-b) / L%; B2≥k(b-b'') / L'%; Groove width value: B = max(B1, B2), where B is the U-shaped groove width; B1 is the groove width calculated based on elastic tension; B2 is the groove width calculated based on elastic compression; b is the actual width of the transverse joint during treatment; b' is the width of the transverse joint at maximum deformation; b'' is the width of the transverse joint at minimum deformation; the units of the above parameters are all cm; the long-term maximum elastic tensile rate of polyurea is L%, generally 15~30%; the long-term maximum elastic compression rate of polyurea is L'%, generally 50%; k is the safety factor, generally 1.2~1.3. The transverse joint U-shaped groove width structure should be suitable for the opening and closing deformation of the transverse joint. When the transverse joint is periodically opened to its maximum, the polyurea does not produce excessive tensile tearing; when periodically closed, the polyurea compresses little and the deformation is easily recovered. The long-term maximum elastic elongation and compression ratio of polyurea should be determined by testing under the same working conditions.

[0047] In another embodiment, the timing of the transverse joint opening construction in step S1 can be flexibly determined based on the specific dam's monitoring data. As long as it is within the range of 65%-75%, a similar effect can be achieved. If the monitoring data shows that the transverse joint deformation is small, the lower limit value can be used for construction; if the deformation is large, the upper limit value can be used for construction to ensure that the material has sufficient tensile and compressive reserves.

[0048] In another embodiment, the range of porosity α in step S2 can be corrected according to the water pressure test data of different dam sections. For joints with high permeability, α can be a larger value (e.g., 0.7-0.8); for joints with low permeability, α can be a smaller value (e.g., 0.5-0.6), so that the theoretical injection volume is more in line with reality.

[0049] In another embodiment, if there are large local cracks on the joint surface in step S2, a small amount of cement grout can be injected first for pre-sealing, and water-soluble polyurethane can be injected after it has solidified to improve the grouting economy.

[0050] In summary, this invention effectively solves the problem of transverse joint leakage in concrete gravity dams by adopting a systematic "interception-blockage-drainage" approach, combined with precise timing of construction, high-precision drilling technology, quantitative grouting control, and the application of high-performance materials. The treatment effect is reliable and durable, and it has good potential for widespread application.

[0051] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims. The above description is merely a preferred embodiment of the present invention and 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 scope of protection of the present invention.

Claims

1. A method for treating seepage at transverse joints of a concrete gravity dam, characterized in that: Includes the following steps, S1, the first composite seepage interception layer is constructed at the transverse joint of the upstream dam face. The first composite seepage interception layer is composed of SR plastic water-stopping material embedded in the U-shaped groove of the transverse joint and polyurea elastic coating covering the dam face and the transverse joint. S2, a second elastic water-stopping barrier is constructed between the two water-stopping barriers in the transverse joint. The second elastic water-stopping barrier is composed of a water-soluble polyurethane grout solidified body injected into the borehole across the joint. S3, a third drainage channel is constructed downstream of the second water stop, the third drainage channel being composed of drainage holes that run through the transverse joint to the lower corridor.

2. The method for treating transverse joint leakage in a concrete gravity dam according to claim 1, characterized in that: The timing of the construction of the first composite cutoff layer is based on dam safety monitoring data, and is chosen when the opening of the transverse joint reaches 65% to 75% of its annual maximum opening.

3. The method for treating transverse joint leakage in a concrete gravity dam according to claim 1, characterized in that: When constructing the first composite cutoff layer, the calculation formula and value for the width of the U-shaped groove are as follows: Slot width calculation: B1≥k(b'-b) / L%; B2≥k(b-b'') / L'% Slot width value: B = max(B1, B2). Where B is the width of the U-shaped groove; B1 is the groove width calculated based on elastic tension; B2 is the groove width calculated based on elastic compression; b is the actual width of the transverse seam during processing; b' is the width of the transverse seam at maximum deformation; b'' is the width of the transverse seam at minimum deformation; the units of the above parameters are all cm; the long-term maximum elastic tensile rate of polyurea is L%; the long-term maximum elastic compression rate of polyurea is L'%; and k is the safety factor.

4. The method for treating transverse joint leakage in a concrete gravity dam according to claim 1, characterized in that: The borehole inclination of the drilled hole is less than 0.1%, and the diameter is not less than 150mm; the drilling position is on the surface of the transverse seam to ensure that the drill hole penetrates and exposes the transverse seam.

5. The method for treating transverse joint leakage in a concrete gravity dam according to claim 3, characterized in that: The construction method of the second elastic waterproof barrier includes the following steps: S21. Based on the actual width b of the transverse joint obtained from core drilling and the area S of the transverse joint between the two waterstops in the grouting section, combined with the porosity α of the transverse joint, calculate the theoretical grouting injection volume Q. 理 ; S22 uses a pure pressure grouting method for graded pressure grouting; S23, during the grouting process, the actual injection volume Q is measured in real time. 实 When Q 实 Reaching Q 理 When the injection rate is less than 0.5 L / min at this pressure level, the grouting is stopped after stabilizing the pressure for 30 minutes; S24, if Q is under the maximum pressure of 0.3MPa 实 Much smaller than Q 理 If 90% of the seal is intact, it is considered a minor seam and requires re-filling with a low-viscosity material; if Q... 实 Far exceeding Q 理 If the grout flow rate is 110%, it is determined that there is a grout leakage channel, and grouting should be suspended and measures such as flow restriction, pressure reduction, waiting for curing, and leak plugging should be taken.

6. The method for treating transverse joint leakage in a concrete gravity dam according to claim 5, characterized in that: In step S21, according to formula Q 理 = πr²L + αSb calculates the theoretical grouting injection volume, where r is the borehole radius, L is the grouting section length, b is the actual width of the transverse joint (all parameters are in cm); S is the transverse joint area between the two waterstops in the grouting section (unit: cm²). 2 α represents the porosity of the transverse seam.

7. A method for treating transverse joint leakage in a concrete gravity dam according to claim 6, characterized in that: In step S21, the transverse joint porosity α ranges from 0.5 to 0.8, and this parameter is corrected by inversion based on the permeability data of the previous exploration borehole water pressure test.

8. A method for treating transverse joint leakage in a concrete gravity dam according to claim 6, characterized in that: In step S21, the grouting adopts a segmented plugging and bottom-up process. In different grouting sections, the transverse joint width b parameter in the theoretical injection volume formula is dynamically adjusted according to the depth of the section, the core sample of the cross joint hole, and the stress condition.

9. A method for treating transverse joint leakage in a concrete gravity dam according to claim 4, characterized in that: In step S22, the grouting pressure is applied in increments of 0.1 MPa, 0.2 MPa, and 0.3 MPa, with each pressure level stabilizing for at least 10 minutes.

10. A method for treating transverse joint leakage in a concrete gravity dam according to claim 1, characterized in that: The third drainage channel is drilled vertically from the top of the dam to the corresponding gallery above the lower part of the dam body, and the seepage water from the horizontal joints is diverted through the borehole to the drainage ditch of the gallery.

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