Cantilever type rigid-flexible anti-seepage structure and construction method thereof

Abstract

The invention provides a cantilever type rigid-flexible anti-seepage structure and a construction method thereof.The cantilever type rigid-flexible anti-seepage structure comprises a plastic concrete flexible anti-seepage wall arranged in a geological soil layer and a reinforced concrete rigid anti-seepage wall coaxially located above the plastic concrete flexible anti-seepage wall, the plastic concrete flexible anti-seepage wall and the reinforced concrete rigid anti-seepage wall are vertically and tightly connected, and a pile cap flush with the ground is arranged at the top of the rigid wall to form a whole; and slope protection feet are arranged on the cantilever sides. During construction, the flexible anti-seepage wall is firstly grooved and poured, then the rigid wall reinforcement cage is installed, after the rigid anti-seepage wall is solidified, the pile caps are constructed to be connected into a whole, and the slope protection feet are excavated and poured on the cantilever side earth of the rigid anti-seepage wall to form the whole rigid and flexible anti-seepage structure. The problems that in a dike project limited by space, a traditional separated structure is high in manufacturing cost and insufficient in anti-shearing capacity are solved.

Description

Technical Field

[0001] This invention relates to the field of dam and water conservancy engineering technology, and in particular to a cantilevered rigid-flexible seepage prevention structure and its construction method. Background Technology

[0002] In the expansion project of the ship lock at the water conservancy hub, the construction of the upstream approach channel slope requires the use of shoreline beach resources. According to the mandatory requirements of the dike engineering specifications, the no-toe protection zone on the water-facing side of important dikes must maintain a complete protection range of no less than 50m. The approach channel slope structure must strictly avoid this dike protection range, preventing any form of encroachment. To meet the functional requirements of the waterway, a 1:3 comprehensive stabilizing slope gradient is adopted, with a single-stage ramp structure. The ramp width is standardized at 3m to meet maintenance and passage requirements. Geotechnical calculations show that in some sections, due to abrupt changes in beach topography and existing structures, conventional slope design would exceed the dike protection boundary. To resolve the spatial constraints and simultaneously ensure the integrity of the dike's seepage prevention system, a new type of slope seepage prevention structure with high space utilization and complete structural functions is urgently needed. Summary of the Invention

[0003] The main objective of this invention is to provide a cantilevered rigid-flexible seepage-proof structure and its construction method, which solves the problems of high cost and weak shear strength of traditional seepage-proof walls and support piles being designed separately.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a cantilevered rigid-flexible seepage prevention structure, including a flexible seepage prevention wall made of plastic concrete, which is vertically installed in the geological soil layer; A rigid cutoff wall is coaxially installed above and connected to the flexible cutoff wall; Pile caps are attached to the top of rigid cutoff walls, with their upper surfaces flush with the ground, and are used to connect the rigid cutoff walls into a whole. Slope protection and toe protection are installed on the cantilever side of the rigid anti-seepage wall.

[0005] In the preferred embodiment, the top of the flexible cutoff wall is provided with multi-level stepped protrusions, and the bottom of the rigid cutoff wall is provided with corresponding multi-level stepped grooves. The multi-level stepped protrusions are embedded in the multi-level stepped grooves, so that the rigid cutoff wall and the flexible cutoff wall form a coaxial interlocking connection structure.

[0006] In the preferred embodiment, the number of steps in the multi-level stepped protrusions at the top of the flexible seepage barrier is 2-3. The height difference between adjacent steps is configured to be 1 / 3 to 1 / 2 of the smaller thickness between the rigid and flexible cut-off walls; Each step has an outward slope on its sidewalls, with the angle between the slope and the vertical axis of the flexible impermeable wall being 5-8°.

[0007] In the preferred embodiment, prestressed tie rods are provided at the anchorage between the slope protection toe and the rigid anti-seepage wall.

[0008] A construction method for a cantilevered rigid-flexible seepage-proof structure, the method comprising: S1. Drill holes to form trenches in the geological soil layer and pour concrete to construct a flexible seepage barrier wall; S2. After the concrete of the flexible seepage barrier wall has initially set, the top layer of the geological soil is expanded to form a trench, and the floating slag on the top of the flexible seepage barrier wall concrete is cleaned. S3. Install the steel cage for the rigid anti-seepage wall and pour concrete. S4. Remove the pile heads of the rigid anti-seepage wall, tie the pile cap reinforcement, install the formwork, and then pour concrete. S5. Excavation of soil on the cantilever side of the rigid anti-seepage wall, construction of slope protection and toe protection, and integration of the rigid anti-seepage wall, flexible anti-seepage wall, and pile cap into a rigid-flexible anti-seepage wall structure.

[0009] In the preferred embodiment, during the initial setting period of the concrete of the flexible seepage barrier, a steel template with a multi-level stepped protrusion profile is pressed into its top. In the preferred embodiment, the formwork construction of the rigid anti-seepage wall in step S3 includes: temporarily fixing and connecting the rigid wall side formwork and the steel formwork to form a closed casting cavity.

[0010] In the preferred embodiment, before the rigid cutoff wall is fully set, the temporary anchoring of the steel formwork to the side formwork of the rigid wall is removed, and the steel formwork is pulled out from the junction of the rigid cutoff wall and the flexible cutoff wall in sections from the side.

[0011] In the preferred embodiment, after the steel formwork is removed, expansive mortar is immediately pressure-injected into the stepped gap at the junction of the rigid and flexible anti-seepage walls.

[0012] In the preferred embodiment, when installing the rigid anti-seepage wall steel cage, the prestressed tie rod bearing anchor plate assembly, prestressed duct, and grouting pipe are simultaneously installed at the corresponding heights of the main reinforcement of the wall and the slope protection toe. The prestressed tie rods are tensioned in stages after the concrete strength of the rigid anti-seepage wall exceeds 80% of the design value, and the duct grouting is completed within 24 hours after tensioning.

[0013] This invention provides a cantilevered rigid-flexible seepage-proof structure and its construction method. This structure significantly improves the overall performance of the seepage-proof system through a combination of rigidity and flexibility. The lower flexible seepage-proof wall uses plastic concrete, which can absorb the stress generated by uneven foundation settlement, and its tensile strain capacity effectively prevents wall cracking. The upper rigid seepage-proof wall provides high-strength support, resisting soil pressure and shear force. The two are coaxially connected to form a synergistic force-bearing system. The slope protection and toe protection are anchored to the rigid wall through prestressed tie rods, enhancing the overturning resistance of the cantilever structure and solving the shear risk caused by composite stress at the inflection point interface.

[0014] The stepped interlocking connection structure significantly optimizes the performance of the rigid-flexible interface. The 2-3 stepped protrusions at the top of the flexible wall interlock with the stepped grooves at the bottom of the rigid wall; the sloping design disperses shear force and reduces stress concentration. The stepped construction extends the seepage path, significantly reducing the risk of joint leakage. The height difference between adjacent steps is set to 1 / 3 to 1 / 2 of the smaller wall thickness, ensuring structural strength while allowing for construction errors and improving the project's tolerance for error.

[0015] Innovative construction techniques have resulted in a dual improvement in quality and efficiency. During the initial setting stage of the flexible wall, steel formwork is pressed in to form a stepped structure, utilizing the self-weight pressure of the rigid concrete during pouring to aid in the compaction of the steps. The steel formwork also serves as the bottom formwork for the rigid wall, creating a closed pouring cavity and ensuring structural geometric accuracy. Before final setting, the steel formwork is removed in sections, and expanding mortar is immediately pressure-injected to actively fill gaps, compensate for shrinkage, and prevent cold joints. The prestressing system is installed synchronously with the reinforcing cage, and tensioning is performed in stages after the concrete strength reaches 80%, with grouting completed within 24 hours, effectively controlling prestress loss.

[0016] The construction scheme offers significant overall economic benefits. This structure replaces the traditional separate system of retaining piles and cutoff walls, reducing concrete usage. The integrated rigid-flexible design saves on the cost of the support structure and shortens the construction period. The low permeability coefficient of the plastic concrete and the self-healing properties of the clay particles upon contact with water enhance long-term seepage control stability and reduce maintenance costs. It also improves space utilization, making it particularly suitable for levee protection zones restricted by terrain, and meets the requirements of no-toe zones. Attached Figure Description

[0017] The present invention will be further described below with reference to the accompanying drawings and embodiments: Figure 1 This is a schematic diagram of the cross-section of the cantilevered rigid-flexible seepage barrier structure of the present invention. Figure 2 This is a schematic diagram of the longitudinal section of the cantilevered rigid-flexible seepage barrier structure of the present invention; Figure 3 This is a structural diagram of the junction between the rigid and flexible seepage barriers during the pouring of the rigid seepage barrier wall of this invention; Figure 4 This is a structural diagram of the junction between the rigid and flexible seepage barriers after the completion of construction of this invention; Figure 5 This is a structural diagram of the connection between the slope protection and the rigid seepage prevention wall of the present invention; Figure 6 This is a flowchart of the construction method for the cantilevered rigid-flexible seepage barrier structure of the present invention.

[0018] In the diagram: 1. Rigid anti-seepage wall; 101. Multi-stage stepped trench; 2. Flexible anti-seepage wall; 201. Multi-stage stepped protrusion; 3. Pile cap; 4. Slope protection and toe protection; 5. Geological soil layer; 6. Prestressed tie rod; 7. Steel formwork; 8. Rigid wall side formwork; 9. Expansive mortar. Detailed Implementation

[0019] Example 1 like Figure 1-5 As shown, a cantilevered rigid-flexible seepage-proof structure includes a flexible seepage-proof wall 2, which is made of plastic concrete and is vertically installed in the geological soil layer 5. Rigid cutoff wall 1 is coaxially positioned above and connected to flexible cutoff wall 2; Pile cap 3 is connected to the top of rigid cutoff wall 1, and its upper surface is flush with the ground. It is used to connect rigid cutoff wall 1 into a whole. Slope protection and toe protection 4 are installed on the cantilever side of the rigid anti-seepage wall 1.

[0020] This application employs a rigid-flexible cutoff wall structure to ensure the dike's impermeability. A diaphragm wall is installed at the cantilever end of the dike to enhance shear resistance. The lower section of the coaxial section uses a plastic concrete cutoff wall, which has good deformation adaptability and can resist uneven foundation settlement, ensuring seepage prevention and sealing. The upper rigid section uses a reinforced concrete continuous wall to provide high-strength support and resist soil pressure and shear force. Through the combination of rigidity and flexibility, both seepage prevention performance and structural stability are achieved, significantly reducing project costs, saving materials, ensuring safety and reliability, and demonstrating good economic benefits. This rigid-flexible cutoff wall replaces traditional support piles, eliminating the need for a separate support structure; the rigid-flexible cutoff wall directly undertakes the support function, reducing costs.

[0021] Plastic concrete achieves a dense microstructure through optimized mix design, and its permeability coefficient is typically controlled within a certain range. ~ With a flow rate on the order of cm / s, far lower than that of ordinary concrete, it can effectively block water seepage. When subjected to water pressure, the clay particles in the material expand when they come into contact with water, which can automatically fill the tiny cracks and improve the long-term seepage prevention stability.

[0022] Although plastic concrete becomes a solid after curing, its flexibility is mainly reflected in its material mechanical properties and structural adaptability. The elastic modulus of ordinary concrete is typically 2.5 × ~3.5× The elastic modulus of plastic concrete is 500-2000 MPa, only 1 / 10 to 1 / 20 that of ordinary concrete. This low elastic modulus gives plastic concrete a rubber-like deformation capacity; when uneven settlement occurs in the foundation, the wall can absorb stress through its own deformation, preventing cracking. The ultimate tensile strain of plastic concrete can reach 0.1-0.3%, while that of ordinary concrete is only 0.01-0.02%, allowing it to withstand greater tensile deformation without breaking.

[0023] Connecting with the rigid section, the flexible deformation of the lower plastic concrete buffers the foundation displacement, protecting the upper rigid wall from shear failure and ensuring overall seepage prevention continuity. The cantilever side slope protection toe restrains soil displacement, further reducing the deformation pressure on the plastic concrete wall.

[0024] In the preferred embodiment, the top of the flexible cut-off wall 2 is provided with multi-level stepped protrusions 201, and the bottom of the rigid cut-off wall 1 is provided with matching multi-level stepped grooves 101. The multi-level stepped protrusions 201 are embedded in the multi-level stepped grooves 101, so that the rigid cut-off wall 1 and the flexible cut-off wall 2 form a coaxially fitted connection structure.

[0025] In the preferred embodiment, the number of steps in the multi-step protrusion 201 at the top of the flexible seepage barrier 2 is 2-3. The height difference between adjacent steps is configured to be 1 / 3 to 1 / 2 of the smaller thickness of the rigid cutoff wall 1 and the flexible cutoff wall 2; Each step has an outward slope on its sidewall, with the angle between its inclination and the vertical axis of the flexible impermeable wall 2 being 5-8°.

[0026] Because the rigid cutoff wall 1 and the flexible cutoff wall 2 are made of different materials and their construction was not synchronized, the connection interface is unstable and has seepage gaps. Traditional solutions often use waterstops, but these waterstops are prone to aging and falling off, affecting their performance.

[0027] This embodiment preferably uses a three-tiered mortise and tenon structure. The shear force at the mortise and tenon joint is reduced by the decomposition of the inclined plane, which reduces stress concentration and cracking. The tiered structure allows for gap construction errors, reducing construction difficulty. At the same time, the tiered structure extends the seepage path and reduces the risk of seepage.

[0028] In the preferred embodiment, a prestressed tie rod 6 is provided at the anchorage between the slope protection and toe protection 4 and the rigid seepage prevention wall 1.

[0029] Since the connection between the slope protection toe 4 and the rigid anti-seepage wall 1 is located on one side, and the cantilevered main body of the slope protection toe 4 is not equipped with other support and anchoring structures, a prestressed structure needs to be set at the connection point between the slope protection toe 4 and the rigid anti-seepage wall 1 to resist the overturning force caused by the slope protection toe 4 itself and the rigid anti-seepage wall 1 after being subjected to external forces.

[0030] Example 2 Further explanation in conjunction with Example 1, such as Figure 1-6 As shown, a construction method for a cantilevered rigid-flexible seepage-proof structure is provided, the method comprising: S1. Drill holes to form trenches in the geological soil layer 5, and pour concrete to construct the flexible seepage barrier wall 2. S2. After the initial setting of the concrete of the flexible seepage barrier wall 2, the top layer of the geological soil layer 5 is expanded to form a trench, and the floating slag on the top of the concrete of the flexible seepage barrier wall 2 is cleaned. S3. Install the steel cage for the rigid anti-seepage wall and pour concrete. S4. Remove the pile head of the rigid anti-seepage wall, tie the pile cap steel bars, install the formwork, and then pour concrete. S5. Excavation of the cantilever side of the rigid anti-seepage wall 1, construction of slope protection and toe protection 4, and the rigid anti-seepage wall 1, flexible anti-seepage wall 2, and pile cap 3 to form a rigid-flexible anti-seepage wall structure.

[0031] In the preferred embodiment, during the initial setting period of the concrete of the flexible seepage barrier 2, a steel formwork 7 with a multi-level stepped protrusion 201 profile is pressed into its top. The initial setting time of plastic concrete is usually 4-6 hours. During this stage, the concrete is in a plastic solid state and exhibits Bingham fluid characteristics, that is, the yield stress is greater than the shear stress. It can withstand the pressure of the formwork without damaging the structure. When the steel formwork 7 is pushed in, it undergoes elastic deformation rather than cracking.

[0032] In the preferred embodiment, the formwork construction of the rigid anti-seepage wall 1 in step S3 includes: temporarily fixing and connecting the rigid wall side formwork 8 and the steel formwork 7 to form a closed casting cavity.

[0033] The steel formwork 7 serves as the top formwork for the flexible anti-seepage wall 2 after its initial setting, and as the bottom formwork for the rigid anti-seepage wall 1 when the concrete is poured. The weight of the rigid concrete further presses the steel formwork 7 against the flexible anti-seepage wall 2 to assist in the formation of the multi-level stepped protrusions 201 at its top.

[0034] In the preferred embodiment, before the rigid cutoff wall 1 is fully set, the temporary anchoring of the steel formwork 7 and the rigid wall side formwork 8 is removed, and the steel formwork 7 is pulled out from the junction of the rigid cutoff wall 1 and the flexible cutoff wall 2 in sections from the side.

[0035] Since the rigid anti-seepage wall 1 exerts a large pressure on the steel formwork 7 at this time, the steel formwork 7 can be demolded and pulled out by hydraulic vibration.

[0036] In the preferred embodiment, after the steel formwork 7 is removed, expansive mortar 9 is immediately pressure-injected into the stepped gap at the junction of the rigid anti-seepage wall 1 and the flexible anti-seepage wall 2.

[0037] After the steel formwork 7 is pulled out, a structural gap is created between the rigid anti-seepage wall 1 and the flexible anti-seepage wall 2. Therefore, an expansion material is used to actively compact the cracks, compensate for concrete shrinkage, and reduce stress concentration at the connection between different materials.

[0038] In the preferred embodiment, when installing the steel cage of the rigid anti-seepage wall 1, the bearing anchor plate assembly of the prestressed tie rod 6, the prestressed duct, and the grouting pipe are simultaneously installed at the corresponding heights of the main reinforcement of the wall and the slope protection and toe protection 4. The prestressed tie rod 6 is tensioned in stages after the concrete strength of the rigid anti-seepage wall 1 is greater than 80% of the design value, and the duct grouting is completed within 24 hours after tensioning.

[0039] When binding the steel reinforcement cage of the rigid wall, the embedded components are welded and positioned with the main reinforcement. The prestressed ducts pass through the bearing plate and are exposed at both ends. One end of the grouting pipe is connected to the lowest point of the duct, and the other end extends to the top of the wall.

[0040] Because the lateral pressure of the slope will cause the slope protection toe 4 to tend to slide outward, it will generate horizontal tensile force at the turning point where it connects with the rigid anti-seepage wall 1. At the same time, the anti-seepage wall needs to resist the seepage force, which further exacerbates the tensile force. The self-weight of the slope protection toe 4 and the vertical load of the slope backfill soil will form downward compressive stress at the turning point. The combination of the horizontal force of water impact and soil pressure with the vertical force of self-weight and compressive stress leads to a relative sliding tendency at the interface of the turning point, generating shear force. Therefore, the prestressed steel bars should protrude outward and bend upward to form reverse compressive stress at the turning point, offsetting the tensile stress, while enhancing the shear resistance of the interface and preventing cracking at the turning point.

[0041] During the overall construction process, it is necessary to wait for the plastic concrete to pass the penetration resistance test to confirm that there is no obvious deformation on the wall surface and no marks left when pressed before carrying out the hole enlargement and trenching operation of the rigid wall.

[0042] Although the final setting time is relatively long, the installation of the steel cage and the pouring of concrete for the rigid wall need to be completed after the initial setting of the flexible wall and before the final setting. This is to avoid the flexible wall having too high a strength after final setting, which would cause "cold joints" at the junction of the rigid and flexible walls and affect the overall seepage prevention effect.

[0043] The above embodiments are merely preferred technical solutions of the present invention and should not be considered as limitations on the present invention. The scope of protection of the present invention should be limited to the technical solutions described in the claims, including equivalent substitutions of the technical features described in the claims. That is, equivalent substitutions and improvements within this scope are also within the scope of protection of the present invention.

Claims

1. A cantilevered rigid-flexible seepage-proof structure, characterized in that: Including flexible The seepage barrier (2) is made of plastic concrete and is vertically installed in the geological soil layer (5); A rigid cutoff wall (1) is coaxially positioned above and connected to the flexible cutoff wall (2); The pile cap (3) is connected to the top of the rigid anti-seepage wall (1), and its upper surface is flush with the ground. It is used to connect the rigid anti-seepage wall (1) into a whole. The slope protection and toe protection (4) are set on the cantilever side of the rigid anti-seepage wall (1).

2. The cantilevered rigid-flexible seepage-proof structure according to claim 1, characterized in that: The top of the flexible seepage barrier (2) is provided with a multi-level stepped protrusion (201), and the bottom of the rigid seepage barrier (1) is provided with a matching multi-level stepped groove (101). The multi-level stepped protrusion (201) is embedded in the multi-level stepped groove (101), so that the rigid seepage barrier (1) and the flexible seepage barrier (2) form a coaxial interlocking connection structure.

3. The cantilevered rigid-flexible seepage-proof structure according to claim 2, characterized in that: The number of steps in the multi-level stepped protrusions (201) at the top of the flexible seepage barrier wall (2) is 2-3. The height difference between adjacent steps is configured to be 1 / 3 to 1 / 2 of the smaller thickness between the rigid cutoff wall (1) and the flexible cutoff wall (2); Each step has an outward slope on its sidewall, and the angle between its inclination and the vertical axis of the flexible impermeable wall (2) is 5-8°.

4. The cantilevered rigid-flexible seepage-proof structure according to claim 1, characterized in that: Prestressed tie rods (6) are installed at the anchorage of the slope protection and toe protection (4) and the rigid seepage prevention wall (1).

5. A construction method for a cantilevered rigid-flexible seepage-proof structure according to any one of claims 1-4, characterized in that: The method includes: S1. Drill holes to form trenches in the geological soil layer (5) and pour concrete to construct a flexible seepage barrier wall (2). S2. After the initial setting of the concrete of the flexible seepage barrier wall (2), the top layer of the geological soil layer (5) is expanded into a trench, and the floating slag on the top of the concrete of the flexible seepage barrier wall (2) is cleaned. S3. Install the rigid anti-seepage wall (1) steel cage and pour concrete; S4. Remove the pile head of the rigid anti-seepage wall (1), tie the pile cap (3) reinforcement, install the formwork and then pour concrete; S5. Rigid anti-seepage wall (1) cantilever side earthwork excavation, construction slope protection and toe protection (4) and rigid anti-seepage wall (1), flexible anti-seepage wall (2) and pile cap (3) are combined to form a rigid and flexible anti-seepage wall structure.

6. The construction method of the cantilevered rigid-flexible seepage-proof structure according to claim 5, characterized in that: During the initial setting period of the concrete of the flexible seepage barrier (2), a steel template (7) with a multi-level stepped protrusion (201) profile is pressed into its top.

7. The construction method of the cantilevered rigid-flexible seepage-proof structure according to claim 6, characterized in that: The formwork construction of the rigid anti-seepage wall (1) in step S3 includes: temporarily fixing and connecting the rigid wall side formwork (8) and the steel formwork (7) to form a closed casting cavity.

8. The construction method of a cantilevered rigid-flexible seepage-proof structure according to claim 5, characterized in that: in Before the rigid anti-seepage wall (1) is fully set, the temporary anchoring of the steel formwork (7) and the rigid wall side formwork (8) is removed, and the steel formwork (7) is pulled out from the side section at the junction of the rigid anti-seepage wall (1) and the flexible anti-seepage wall (2).

9. The construction method of the cantilevered rigid-flexible seepage-proof structure according to claim 8, characterized in that: After the steel formwork (7) is removed, immediately inject expansive mortar (9) into the stepped gap at the junction of the rigid anti-seepage wall (1) and the flexible anti-seepage wall (2).

10. The construction method of the cantilevered rigid-flexible seepage-proof structure according to claim 5, characterized in that: When installing the steel cage of the rigid anti-seepage wall (1), the pressure anchor plate assembly of the prestressed tie rod (6), the prestressed duct and the grouting pipe are installed at the corresponding height of the main reinforcement of the wall and the slope protection and toe protection (4); The prestressed tie rod (6) is tensioned in stages after the concrete strength of the rigid anti-seepage wall (1) is greater than 80% of the design value, and the duct grouting is completed within 24 hours after tensioning.

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