Rigid-flexible combined reinforcing method for controlling earthquake deformation of dam foundation of concrete faced rockfill dam on deep and thick covering layer

Abstract

The invention provides a rigid-flexible combined reinforcing method for controlling earthquake deformation of a dam foundation of a concrete faced rockfill dam on a deep and thick covering layer, and belongs to the technical field of water conservancy projects. Comprising the steps that (1) concrete piles and gravel piles are arranged in a covering layer to form a composite foundation system, the concrete piles provide rigid vertical support, and the gravel piles improve the drainage performance of a foundation and reduce the liquefaction risk; (2) geogrids are laid in a layered mode, the upstream sides and the downstream sides of the geogrids are turned up to the slope surface to form wrapping sections, flexible horizontal constraint is formed, and the deformation coordination of the dam body and the covering layer is enhanced; and (3) steel bars are laid every three layers of geogrids, the steel bars are connected with the concrete lattice beams through the concrete anchoring sections, the restraining effect of the surface of the dam foundation is improved, the overall deformation coordination of the dam foundation is improved, and the horizontal deformation gradient of the dam foundation in the depth direction is reduced. Through the combination of rigid and flexible structures, the deformation resistance of the covering layer is enhanced, the deformation coordination of the dam body and the covering layer is improved, the risks of earthquake settlement and horizontal lateral displacement deformation are reduced, the overall anti-seismic property and stability of the dam body are improved, and the method is suitable for dam foundation reinforcement of earth and rockfill dam engineering on the complex deep and thick covering layer.

Description

Technical Field

[0001] The present invention belongs to the technical field of water conservancy engineering, and relates to a rigid-flexible combined reinforcement method for controlling the seismic deformation of a slab rockfill dam foundation on a thick overburden layer, and is particularly suitable for a method and a construction process for enhancing the stability and seismic performance of a thick overburden foundation through a composite flexible and rigid structure. Background Art

[0002] With the rapid development of water conservancy projects in my country, earth-rock dams are widely used in various water conservancy projects due to their economy and adaptability. However, when the dam body needs to be built on a thick overburden, the foundation conditions are complex, which may lead to uneven deformation of the dam body and foundation, and insufficient deep anti-sliding stability, especially under earthquakes.

[0003] In current technology, foundation reinforcement mostly adopts direct excavation, vibro-stone piles, consolidation grouting and other methods. Although these methods can improve the bearing capacity of the foundation to a certain extent, they cannot effectively control the uneven deformation and value of the face rockfill dam foundation on the deep overburden under complex load conditions, especially the horizontal deformation.

[0004] In order to solve the deformation coordination and seismic resistance problems between the thick covering layer and the dam body, the present invention proposes a rigid-flexible combined reinforcement method for controlling the seismic deformation of the dam foundation of a panel rockfill dam on a thick covering layer. By combining the rigid support of concrete piles with the flexible constraint of geogrids, a composite reinforcement system is formed, which significantly improves the overall stability and seismic resistance of the dam body and foundation. Summary of the invention

[0005] The purpose of the present invention is to provide a rigid-flexible combined reinforcement method for controlling the seismic deformation of the foundation of a panel rockfill dam on a deep covering layer. Concrete piles are used to provide deep rigid vertical support, and geogrids are used to achieve horizontal flexible constraints. The two work together to enhance the deformation resistance of the covering layer, improve the deformation coordination between the dam body and the covering layer, reduce the risk of earthquake settlement and horizontal lateral deformation, and improve the overall seismic resistance and stability of the dam body.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] A rigid-flexible combined reinforcement method for controlling seismic deformation of a face rockfill dam foundation on a thick overburden layer, the rigid-flexible combined reinforcement method is based on a geogrid 4, a pre-supported concrete anchoring section 6, a steel bar 5, a concrete lattice beam 7, a concrete pile 1, and a crushed stone pile 2, and specifically comprises the following steps:

[0008] Concrete piles 1 and gravel piles 2 are arranged in the covering layer to form a composite foundation system. The concrete piles 1 penetrate the covering layer to provide rigid support, and a concrete square plate 3 is arranged on the top of the concrete piles 1, which is integrally cast with the geogrid 4; the gravel piles 2 are used to improve the drainage performance of the foundation and reduce the risk of liquefaction. During the dam body filling process, the geogrids 4 are laid in layers, and the upstream and downstream sides of the geogrids 4 are rolled up to the slope to form a wrapping section, forming a flexible constraint, and enhancing the deformation coordination between the dam body and the covering layer. The geogrid 4 is provided with a layer of steel bars 5 every three layers, and the steel bars 5 are fixed by a concrete anchoring section 6, and the ends thereof are connected to the concrete frame beams 7; the concrete frame beams 7 are arranged on the downstream slope of the dam body, and the concrete frame beams 7 are integrally connected to the steel bars 5 and the geogrid 4 in the dam body, which increases the constraint effect on the dam foundation surface, improves the overall deformation coordination of the dam foundation, and reduces the horizontal deformation gradient of the dam foundation along the depth direction.

[0009] Furthermore, the pile length of the concrete pile 1 is the depth of the thick covering layer plus the embedding depth, and the pile length of the gravel pile 2 is the depth of the thick covering layer. The pile diameters and pile spacings of the concrete pile 1 and the gravel pile 2 are determined through dam stability analysis.

[0010] Furthermore, the top of the concrete pile 1 is located at the starting layer for laying the geogrid 4, and a concrete square plate 3 with a side length of 1 to 2 m and a thickness of 30 to 50 cm is provided on the top of the pile. The square plate 3 is located above the first layer of geogrid 4 on the surface of the dam foundation, and is integrally cast with the geogrid 4 and the concrete on site.

[0011] Furthermore, the geogrid 4 is laid after each layer of rockfill is rolled, and the geogrid 4 extends to the slope surface and rolls upward to form a wrapping section.

[0012] Furthermore, the geogrid 4 is not allowed to have wrinkles when being laid, and is fixed on the rockfill with U-shaped nails, and the overlapping positions of the upper and lower layers should be staggered.

[0013] Furthermore, the vertical spacing between adjacent layers of the geogrid 4 is 2 to 3 m.

[0014] Furthermore, the concrete anchoring section 6 is a pre-supported concrete cube block with a side length of 30 to 50 cm.

[0015] Furthermore, the steel bars 5 are threaded steel bars with a diameter of 20 to 30 mm, the horizontal laying length of the steel bars 5 is 10 to 30 m, and the horizontal spacing between adjacent steel bars 5 in the same layer is 1 to 3 m.

[0016] Furthermore, the steel bars 5 are laid in every three layers of geogrid 4. When the steel bars 5 are laid in the same layer of geogrid 4, the steel bars 5 are laid under the geogrid 4. At a distance of 1 m from the concrete anchoring section 6, the inner end of the steel bars is bent upward to pass through the geogrid 4 and consolidated with the anchoring section.

[0017] Furthermore, asphalt is poured on the surface of the steel bar 5 for rust prevention.

[0018] Furthermore, one end of the steel bar 5 is cast on site with the concrete lattice beam 7 of the downstream dam slope, and the other end is fixed to the concrete anchoring section 6 buried in the dam body.

[0019] Furthermore, the concrete lattice beams 7 are arranged in a crisscross pattern on the downstream dam body slope, and the horizontal and vertical spacings are the same as the spacings of the steel bars 5 .

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The rigid-flexible combined reinforcement method for earthquake deformation of deep overburden dam foundation proposed in the present invention can improve the seismic resistance of the panel dam on the deep overburden. It is mainly reflected in the fact that the concrete piles provide deep rigid vertical support, the geogrids enhance the horizontal flexible constraints, and improve the deformation coordination ability of the dam body and the overburden; the crushed stone piles improve the drainage performance of the overburden and reduce the possibility of liquefaction deformation; this method is suitable for the foundation reinforcement of earth-rock dam projects on complex and deep overburden. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a structural schematic diagram of the rigid-flexible combined reinforcement of the present invention.

[0023] Figure 2 It is a composite structure composed of concrete piles and geogrids.

[0024] In the figure: 1 concrete pile; 2 gravel pile; 3 square plate; 4 geogrid; 5 steel bar; 6 concrete anchor section; 7 concrete frame beam. DETAILED DESCRIPTION

[0025] The implementation of the method of the present invention is described in detail below in conjunction with the accompanying drawings, but they do not constitute a limitation of the present invention and are only used as examples. At the same time, the advantages of the method of the present invention will become clearer and easier to understand through the description.

[0026] The purpose of the present invention is to provide a rigid-flexible combined reinforcement method for controlling the seismic deformation of the foundation of a panel rockfill dam on a deep covering layer. Concrete piles are used to provide deep rigid vertical support, and geogrids are used to achieve horizontal flexible constraints. The two work together to enhance the deformation resistance of the covering layer, improve the deformation coordination between the dam body and the covering layer, reduce the risk of earthquake settlement and horizontal lateral deformation, and improve the overall seismic resistance and stability of the dam body.

[0027] like Figure 1As shown, a structure of a rigid-flexible combined reinforcement method for controlling the seismic deformation of the foundation of a face rockfill dam on a deep overburden layer includes a concrete pile 1, a crushed stone pile 2, a square plate 3, a geogrid 4, a steel bar 5, a concrete anchoring section 6, and a concrete lattice beam 7. Concrete piles 1 and crushed stone piles 2 are arranged in the reinforcement area of ​​the overburden layer. The crushed stone piles 2 are used to enhance the drainage capacity of the foundation and reduce the risk of liquefaction. The concrete piles 1 penetrate the overburden layer and are connected to the upper structure. A square concrete plate 3 is arranged on the top of the concrete piles 1, which is integrally cast with the geogrid 4 to limit the lateral deformation of the deep soil. The dam material filling body in the seismic zone is provided with multiple layers of geogrids 4 according to the number of rolling layers. The geogrids 4 extend to the slope along the upstream and downstream of the dam body and are rolled up to form a wrapping section, which further enhances the coordination between the dam body and the overburden layer and prevents lateral deformation. A layer of steel bar 5 is arranged every three layers of the geogrid 4. One end of the steel bar 5 is fixed to the concrete anchoring section 6, and the other end is integrally cast with the concrete lattice beam 7. The specific operation process is as follows:

[0028] 1) According to the geological conditions, the concrete pile 1 is designed to be a bored cast-in-place pile with a length of 33m and a diameter of 0.8m, with a pile spacing of 2.5m; the gravel pile 2 is a vibrated gravel pile with a length of 30m and a diameter of 0.6m, with a pile spacing of 2m, and is filled in layers with medium-coarse graded gravel with a particle size of 30mm and filled densely. A square plate 3 with a side length of 1.5m is set on the top of the concrete pile 1, and the square plate 3 is 50cm thick and is cast integrally with the geogrid 4.

[0029] 2) Fill the rockfill in layers and compact it with vibration. Within the range from the dam foundation surface to 1 / 4 of the dam height, lay the geogrid 4 after each layer of rolled rockfill. No wrinkles are allowed during laying. After each layer is laid, roll the outer end of the geogrid 4 upward to the slope to form a wrapping section. The vertical spacing between adjacent layers of geogrid 4 is 2.5m.

[0030] 3) Every three layers, steel bars 5 are laid on the lower side of geogrid 4 and asphalt is poured for rust prevention. Steel bars 5 are 30mm threaded steel bars. The horizontal laying length of steel bars 5 is 30m. The horizontal spacing between adjacent steel bars 5 in the same layer is 3m. The inner end of the steel bar is bent upward and passed through the geogrid 4 to connect with the concrete anchor section 6. The outer end of the steel bar 5 extends 1m above the dam surface and connects with the frame beam 7.

[0031] 4) The rockfill is filled in layers according to the designed layer thickness (0.5-1m), and compacted by vibration rolling. In this embodiment, the rockfill is filled in layers, and the thickness of each layer is 0.8m. The frame beams 7 are arranged in a well shape on the downstream dam slope, with horizontal and vertical spacing of 2m. C30 and above high-grade concrete is used for casting and forming, and the construction is carried out in layers and cured until it is completely hardened.

[0032] Adaptive changes made according to actual needs are all within the protection scope of the present invention.

[0033] The present invention is not limited to the specific details of the above embodiments, and any improvements or equivalent variations within the scope of the claims belong to the protection scope of the present invention. The reference numerals are only for ease of understanding and should not be regarded as limiting the scope of the claims.

Claims

1. A rigid-flexible combined reinforcement method for controlling the seismic deformation of the foundation of a face rockfill dam on a thick overburden layer, characterized in that: The rigid-flexible combined reinforcement method is implemented based on geogrids (4), pre-supported concrete anchoring sections (6), steel bars (5), concrete lattice beams (7), concrete piles (1), and gravel piles (2), and comprises the following steps: Concrete piles (1) and gravel piles (2) are arranged in the covering layer to form a composite foundation system; the concrete piles (1) penetrate the covering layer, and a concrete square plate (3) is arranged on the top of the concrete piles (1) and cast integrally with the geogrid (4); During the dam body filling process, geogrids (4) are laid in layers, and a layer of steel bars (5) is arranged every other layer of the geogrids (4). The inner ends of the steel bars (5) are fixed by concrete anchoring sections (6), and the outer ends of the steel bars (5) are connected to concrete frame beams (7); The concrete lattice beam (7) is arranged on the downstream slope of the dam body, and the concrete lattice beam (7) is integrally connected to the steel bars (5) and the geogrid (4) in the dam body.

2. A rigid-flexible combined reinforcement method for controlling seismic deformation of a face rockfill dam foundation on a thick overburden layer according to claim 1, characterized in that: The geogrid (4) is laid after each layer of rockfill is rolled, and the geogrid (4) extends to the slope surface and rolls upward to form a wrapping section, thereby forming a flexible constraint.

3. A rigid-flexible combined reinforcement method for controlling seismic deformation of a face rockfill dam foundation on a thick overburden layer according to claim 1, characterized in that: The geogrid (4) is provided with a layer of steel bars (5) every three layers; When the steel bars (5) are laid on the same layer as the geogrid (4), the steel bars (5) are laid under the geogrid (4); The inner end of the steel bar (5) is bent upward and passes through the geogrid (4) to be fixed to the concrete anchoring section (6) buried in the dam body, and the outer end is cast on site together with the concrete frame beam (7) on the downstream dam slope.

4. A rigid-flexible combined reinforcement method for controlling seismic deformation of a face rockfill dam foundation on a thick overburden layer according to claim 1, characterized in that: The pile length of the concrete pile (1) is the depth of the thick covering layer plus the embedding depth, and the pile length of the gravel pile (2) is the depth of the thick covering layer. The pile diameters and pile spacings of the concrete pile (1) and the gravel pile (2) are determined by calculating the stability of the dam.

5. The rigid-flexible combined reinforcement method for controlling seismic deformation of the foundation of a face rockfill dam on a thick overburden layer according to claim 1 is characterized in that: The top of the concrete pile (1) is located at the starting layer of the geogrid (4), and a concrete square plate (3) with a side length of 1 to 2 m and a thickness of 30 to 50 cm is arranged on the top of the pile; the concrete square plate (3) is located above the first layer of geogrid (4) on the surface of the dam foundation, and is integrally cast with the geogrid (4) and concrete on site.

6. A rigid-flexible combined reinforcement method for controlling seismic deformation of a face rockfill dam foundation on a thick overburden layer according to claim 1, characterized in that: The geogrid (4) is fixed on the rockfill during paving, and the overlapping positions of the upper and lower layers are staggered.

7. A rigid-flexible combined reinforcement method for controlling seismic deformation of a face rockfill dam foundation on a thick overburden layer according to claim 6, characterized in that: The vertical spacing between adjacent layers of the geogrid (4) is 2 to 3 m.

8. The rigid-flexible combined reinforcement method for controlling seismic deformation of a face rockfill dam foundation on a thick overburden layer according to claim 1 is characterized in that: The concrete anchoring section (6) is a pre-supported concrete cube block with a side length of 30 to 50 cm.

9. The rigid-flexible combined reinforcement method for controlling seismic deformation of the foundation of a face rockfill dam on a thick overburden layer according to claim 1 is characterized in that: The concrete lattice beams (7) are arranged in a crisscross pattern on the downstream dam body slope, and the horizontal and vertical spacings are the same as the spacings of the steel bars (5).

10. The rigid-flexible combined reinforcement method for controlling seismic deformation of the foundation of a face rockfill dam on a thick overburden layer according to claim 1, characterized in that: The steel bars (5) are threaded steel bars with a diameter of 20 to 30 mm. The horizontal laying length of the steel bars (5) is 10 to 30 m, and the horizontal spacing between adjacent steel bars (5) in the same layer is 1 to 3 m. The surface of the steel bars (5) is poured with asphalt for rust prevention.

Images