Rapid protection structure and construction method for seepage points on earth-rock dam slope during construction period

Abstract

This invention belongs to the field of water conservancy and hydropower engineering technology, specifically relating to a rapid protection structure for seepage points on the slope of an earth-rock dam during construction and its construction method. The protection structure includes: a seepage point collection unit for collecting seepage from one or more seepage points; a deeply buried drainage unit connected to the seepage point collection unit for systematically discharging the collected seepage; a reverse filtration and anti-siltation unit surrounding the deeply buried drainage unit to prevent sediment particles from entering and causing blockage; and a composite sealing unit covering the deeply buried drainage unit and the surrounding slope surface to isolate surface water infiltration and stabilize the slope surface. This protection structure does not rely on precise detection of the upstream seepage path. For exposed seepage points, it safely, reliably, and effectively guides and discharges seepage, while ensuring that the construction face of the core dam is not affected, and facilitating subsequent possible permanent seepage prevention treatment.

Description

Technical Field

[0001] This invention belongs to the field of water conservancy and hydropower engineering technology, specifically relating to a rapid protection structure for seepage points on the slope of an earth-rock dam during construction and its construction method. Background Technology

[0002] During the construction of clay-core earth-rock dams, localized, point-like seepage often occurs on the dam foundation slopes (especially the slopes in contact with the core wall) due to geological structure, rainfall infiltration, and other factors. Because the slopes are usually quite thick and the geological conditions are complex and variable, the exact source and seepage path of the seepage are often difficult to determine in a short time, which poses a great challenge to the treatment work.

[0003] If the water from these seepage points is allowed to flow into the clay filling area of ​​the core wall, the moisture content of the filling material will exceed the standard, thus affecting the compaction effect and resulting in insufficient compaction. This will not only delay the construction progress, but more seriously, it will weaken the performance of the core wall as the core seepage barrier, leaving potential risks to the project quality.

[0004] Currently, the conventional methods for dealing with this type of problem mainly include the following: First, the sealing method. This involves directly sealing the seepage point using materials such as quick-setting cement and chemical grouting. While this method is fast-acting, it only addresses the localized area and does not eliminate the seepage pathway. Sealing can cause the upstream seepage head to rise, leading to water pressure buildup. This could potentially trigger new and more concentrated leaks at other vulnerable locations near the sealed point, posing a safety hazard.

[0005] Second, large-scale seepage prevention treatment, such as large-scale curtain grouting. Although this method can fundamentally stop seepage, it involves a large amount of work, high costs, and a long construction period. It is not quick to respond to or economical problems caused by temporary, sudden, and localized seepage during construction.

[0006] Third, the surface drainage method. Drainage pipes are laid at the seepage point to guide the water downstream. The disadvantage of this method is that the drainage pipes are directly exposed to the construction environment and are easily damaged by construction machinery and vehicles; more importantly, due to the lack of effective back-filtration protection, fine particles such as mud and sand carried from rock fissures will quickly clog the pipes, causing the drainage function to fail in the short term.

[0007] In summary, existing technologies either only address the symptoms and not the root cause, pose safety risks, are uneconomical and unsuitable for emergency scenarios, or lack durability. They are insufficient to achieve effective and long-term control of water seepage while ensuring construction progress. Therefore, there is an urgent need for a systematic solution that can balance reliability, durability, economy, and ease of construction. Summary of the Invention

[0008] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a rapid protection structure for seepage points on the slope of an earth-rock dam during construction, along with its construction method. This protection structure does not rely on precise detection of the upstream seepage path. For exposed seepage points, it uses an integrated, multi-layered protection structure to safely, reliably, and effectively guide and drain the seepage, while ensuring that the construction face of the core wall dam is not affected, and facilitating possible subsequent permanent seepage prevention treatment.

[0009] To achieve the above objectives, the present invention adopts the following technical solution: A rapid protection structure for seepage points on the slope of an earth-rock dam during construction includes: A seepage point collection unit is used to collect seepage from one or more seepage points; The deep-buried drainage unit includes a main pipe (3) connected to the seepage point collection unit, which is used to discharge the collected seepage water in an organized manner. The reverse filtration and anti-siltation unit is wrapped around the periphery of the deep-buried drainage unit to prevent silt particles from entering the deep-buried drainage unit and causing siltation. A composite sealing unit covers the deep-buried drainage unit and the surrounding slope surface to isolate surface water infiltration and stabilize the slope surface.

[0010] Preferably, the seepage point collection unit includes: a groove (11) formed by locally expanding the seepage point location, and a branch pipe (4) with one end extending into the groove (11) and the other end connected to the main pipe (3); when there are multiple seepage points, multiple branch pipes (4) are respectively connected to the main pipe (3) through a tee fitting.

[0011] Preferably, the deep-buried drainage unit further includes a trench formed along the slope surface, and the main pipe (3) and branch pipe (4) are disposed in the trench; More preferably, the main pipe (3) and the branch pipe (4) are selected from at least one of perforated HDPE plastic perforated pipe, PVC perforated pipe, and steel-reinforced polyethylene spiral corrugated pipe, so as to facilitate the collection of peripheral seepage.

[0012] Preferably, the reverse filtration and anti-siltation unit includes: a concrete cushion layer (8) laid at the bottom of the trench, a permeable geotextile (7) wrapped around the main pipe (3) and the branch pipe (4), and a graded reverse filter material (9) filled between the permeable geotextile (7) and the trench wall.

[0013] Preferably, the particle size distribution of the graded filter media (9) meets the Terzaghi filter criterion (e.g., D). 15 / d 85 ≤ 4~5), ensuring that it is permeable only to water and not to soil; More preferably, the material of the graded filter media (9) is selected from at least one of gravel, crushed stone, and ceramsite.

[0014] Preferably, the composite sealing unit includes: a steel mesh laid on the surface of the trench and the surrounding slope, and a concrete sealing layer (10) sprayed onto the steel mesh.

[0015] Preferably, the structure further includes an auxiliary drainage unit, which includes drainage holes (6) provided along the inner slope of the concrete sealing layer (10) to reduce the pore water pressure inside the slope and further improve the stability of the slope.

[0016] The present invention also provides a corresponding construction method, comprising the following steps: Construction of the drainage system: Locally expand the seepage point (2) on the slope to form a groove (11), and excavate the pipe trench along the predetermined drainage path; extend the branch pipe (4) into the seepage fissure and connect it with the main pipe (3), and extend the outlet end of the main pipe (3) to the downstream safe area; Construction of the reverse filter system: After pouring a concrete cushion layer (8) at the bottom of the trench, laying the main pipe (3) and branch pipe (4), the permeable geotextile (7) is wrapped and the graded reverse filter material (9) is backfilled in sequence; Surface sealing construction: A steel mesh is laid on the surface of the trench and the surrounding slope, and concrete is sprayed on the steel mesh to form a concrete sealing layer (10), which completely covers and protects the collection system and the filter system.

[0017] Preferably, prior to the surface sealing construction, the following steps are also included: Construction of auxiliary drainage holes: Drill several drainage holes (6) in the slope area to be sealed, and optionally install PVC blind pipes.

[0018] Preferably, during the construction of the reverse filter system, when the main pipe (3) is laid along the trench, its longitudinal slope is not less than 1% to ensure gravity-fed drainage.

[0019] Compared with existing technologies, the beneficial effects of the present invention are at least as follows: (1) Strong systematic approach and thorough treatment: This invention forms a complete seepage control closed loop through the integrated design of "collection-drainage-back-filtration-closure". It does not use forced sealing, but transforms blocking into guidance, and discharges seepage water in an orderly manner, fundamentally eliminating the risk of new leakage points caused by water pressure accumulation; (2) Good durability and long-term effectiveness: Through the combination of deep buried drainage unit and multi-layer reverse filter anti-siltation unit (geotextile + graded material), the drainage pipe is effectively protected and can resist siltation for a long time, ensuring the long-term smoothness and effectiveness of the drainage system, which is far superior to the surface pipe that is easily damaged and silted up. (3) High safety and guaranteed construction: The composite sealing unit not only isolates external rainwater infiltration, but also reinforces the surface of the slope. The auxiliary drainage unit further reduces the internal water pressure of the slope and improves the overall stability; (4) Good connection and long-term consideration: As a temporary protective measure during the construction period, the location of the buried drainage pipeline can be recorded, which provides a precise location basis for the seepage advantage channel when permanent curtain grouting and other seepage prevention treatments are required in the later period, and realizes a good connection between temporary measures and permanent projects; (5) Wide applicability, economical and fast: This method is highly targeted, the construction technology is mature, the required materials are common, and it can be flexibly adjusted according to the amount of seepage and geological conditions on site. It can quickly respond to sudden seepage problems on the construction site and has high economic efficiency and implementation efficiency. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the overall protective structure in Embodiment 1 of the present invention.

[0021] Figure 2 It is along Figure 1 The cross-sectional diagrams of the AA and BB lines respectively show the cross-sectional structures of the main pipe and branch pipe; the left diagram is the cross-sectional diagram of the AA line, and the right diagram is the cross-sectional diagram of the BB line.

[0022] In the diagram: 1-slope, 2-seepage point, 3-main pipe, 4-branch pipe, 5-PVC tee fitting, 6-drainage hole, 7-permeable geotextile, 8-concrete cushion layer, 9-graded filter material, 10-concrete sealing layer, 11-groove. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely below. The following embodiments are used to illustrate the present invention, but are not intended to limit the scope of the present invention. Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in the art, or in accordance with the product manual.

[0024] Example 1 This embodiment was applied to the construction site of a clay-core earth-rock dam in Guizhou Province. Five relatively concentrated seepage points (2) were found on the left bank slope (1) of the dam, within an elevation range of 1015m to 1019m, with a total outflow of approximately 1.5 L / s. The seepage directly affected the construction of the core wall filling area. Due to the thick mountain, the seepage path could not be determined. To quickly address the issue and restore construction, the protective structure and construction method of this invention were adopted.

[0025] Step 1: Exploration and Preparation First, clear the loose soil and rock around the seepage point. For each seepage point (2), locally expand the excavation to form a groove (11) with an entrance about the size of a funnel and a height, width and depth of about 150cm, so as to fully expose the seepage cracks and facilitate subsequent water collection.

[0026] Meanwhile, Φ50 drainage holes (6) are arranged at 2.5m intervals on the inner slope that is about to be closed. The holes are 5m deep and 10° up. PVC blind pipes are installed in the holes to reduce the pore water pressure inside the slope.

[0027] Subsequently, based on the location of the seepage point and the terrain, the direction of the main pipe (3) and the branch pipe (4) was planned, and a pipe trench with a width of 80~100cm and a depth of 80~100cm was excavated on the surface of the slope (1) along the planned path.

[0028] Step 2: Installation of the collection and routing system This step integrates the construction of seepage point collection units, deep-buried drainage units, and reverse filtration and silt prevention units.

[0029] like Figure 1 As shown, a DN200 HDPE plastic perforated pipe is used as a branch pipe (4) and inserted into the water outlet crack of the seepage point (2). The branch pipe (4) is connected to the main pipe (3) of the same DN200 HDPE plastic perforated pipe through a PVC tee fitting (5).

[0030] The main pipe (3) and branch pipe (4) are laid along the pre-excavated trench. To ensure smooth drainage, a 20cm thick C20 concrete cushion layer (8) is poured at the bottom of the trench before laying, and its top surface is precisely controlled to form a longitudinal slope of not less than 1%. The main pipe (3) and branch pipe (4) are placed on the concrete cushion layer (8), and the outlet end of the main pipe (3) extends to the downstream rockfill area to avoid backflow of external water sources.

[0031] After the main pipe (3) and branch pipe (4) are in place, the reverse filtration and anti-siltation unit is constructed. Figure 2 As shown, the main pipe (3) and branch pipe (4) are first completely wrapped with a layer of permeable geotextile (7). Then, a 20cm thick layer of graded filter material (9) is backfilled around the pipes, between the permeable geotextile (7) and the trench wall. In this example, the graded filter material (9) is made of crushed stone with a particle size of 0.5mm to 5mm. Its gradation meets the Terzaghi filter criterion and can effectively prevent fine particles generated by the weathering of mudstone on the slope from entering the pipes and prevent clogging.

[0032] Step 3: Construction of Composite Enclosed Units After completing the construction of the above-mentioned pipelines and filter layer, the entire treatment area (including the trench area and its surrounding slopes) is surface sealed.

[0033] First, a steel mesh of Φ8@20cm×20cm is laid on the surface of the trench area and its surrounding slope. Then, C20 concrete is sprayed twice using a wet spraying process to form a concrete sealing layer (10) with a total thickness of 30cm. This concrete sealing layer (10) smoothly transitions with the surrounding untreated slope, completely covering all internal structures (grooves, pipes, filter materials, etc.) to form a unified and robust protective surface that not only isolates external rainwater infiltration but also enhances the surface's resistance to erosion.

[0034] Implementation effect After the protective structure was completed, all seepage was successfully introduced into the drainage system and discharged downstream through the main pipe (3), and the core wall filling surface was restored to dryness. The subsequent clay filling compaction test passed 100%. In the following rainy season, the treated area withstood multiple heavy rainfalls without any leakage, deformation or damage, and no new concentrated leakage points appeared in the surrounding area, proving that the structure of the present invention is stable, the drainage is reliable, and the effect is long-lasting.

[0035] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A rapid protection structure for seepage points on the slope of an earth-rock dam during construction, characterized in that, include: A seepage point collection unit is used to collect seepage from one or more seepage points; The deep-buried drainage unit includes a main pipe (3) connected to the seepage point collection unit, which is used to discharge the collected seepage water in an organized manner. The reverse filtration and anti-siltation unit is wrapped around the periphery of the deep-buried drainage unit to prevent silt particles from entering the deep-buried drainage unit and causing siltation. A composite sealing unit covers the deep-buried drainage unit and the surrounding slope surface to isolate surface water infiltration and stabilize the slope surface.

2. The rapid protection structure for seepage points on the slope of an earth-rock dam during construction, as described in claim 1, is characterized in that... The seepage point collection unit includes: a groove (11) formed by locally expanding the seepage point location, and a branch pipe (4) with one end extending into the groove (11) and the other end connected to the main pipe (3); when there are multiple seepage points, multiple branch pipes (4) are respectively connected to the main pipe (3) through a tee fitting.

3. The rapid protection structure for seepage points on the slope of an earth-rock dam during construction, as described in claim 2, is characterized in that... The deep-buried drainage unit also includes a trench formed along the slope surface, and the main pipe (3) and branch pipe (4) are set in the trench; Preferably, the main pipe (3) and the branch pipe (4) are selected from at least one of the following: perforated HDPE plastic perforated pipe, PVC perforated pipe, and steel-reinforced polyethylene spiral corrugated pipe.

4. The rapid protection structure for seepage points on the slope of an earth-rock dam during construction, as described in claim 3, is characterized in that... The reverse filtration and anti-siltation unit includes: a concrete cushion layer (8) laid at the bottom of the trench, a permeable geotextile (7) wrapped around the main pipe (3) and the branch pipe (4), and a graded reverse filter material (9) filled between the permeable geotextile (7) and the trench wall.

5. A rapid protection structure for seepage points on the slope of an earth-rock dam during construction, as described in claim 4, is characterized in that... The particle size distribution of the graded filter media (9) meets the Terzaghi filter criterion. Preferably, the material of the graded filter media (9) is selected from at least one of sand, gravel, crushed stone, and ceramsite.

6. A rapid protection structure for seepage points on the slope of an earth-rock dam during construction, as described in any one of claims 3-5, is characterized in that... The composite sealing unit includes: a steel mesh laid on the surface of the trench and the surrounding slope, and a concrete sealing layer (10) sprayed onto the steel mesh.

7. A rapid protection structure for seepage points on the slope of an earth-rock dam during construction, as described in claim 6, is characterized in that... It also includes an auxiliary drainage unit, which includes drainage holes (6) set along the inner slope of the concrete sealing layer (10) to reduce the pore water pressure inside the slope.

8. A construction method for a rapid protection structure for seepage points on the slope of an earth-rock dam during the construction period, as described in any one of claims 1-7, characterized in that, Includes the following steps: Construction of the drainage system: Locally expand the seepage point (2) on the slope to form a groove (11), and excavate the pipe trench along the predetermined drainage path; extend the branch pipe (4) into the seepage fissure and connect it to the main pipe (3); Construction of the reverse filter system: After pouring a concrete cushion layer (8) at the bottom of the trench, laying the main pipe (3) and branch pipe (4), the permeable geotextile (7) is wrapped and the graded reverse filter material (9) is backfilled in sequence; Surface sealing construction: A steel mesh is laid on the surface of the trench and the surrounding slope, and concrete is sprayed on the steel mesh to form a concrete sealing layer (10).

9. The construction method according to claim 8, characterized in that, Prior to the surface sealing construction, the following steps are also included: Construction of auxiliary drainage holes: Drill several drainage holes in the slope area to be sealed (6).

10. The construction method according to claim 8 or 9, characterized in that, During the construction of the reverse filter system, when the main pipe (3) is laid along the trench, its longitudinal slope shall not be less than 1%.

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