A thick overburden pile foundation concrete composite dam structure and its construction method

Abstract

The present invention discloses a deep overburden pile foundation concrete composite dam structure and its construction method. The pile foundation concrete composite dam structure comprises several hollow concrete dam sections, with upstream slope angles of 50° to 80° and downstream slope angles of 80° to 90°. Rubber pads are installed at the joints between the concrete dam sections and connected via dampers, which are located in the cavities of the concrete dam sections. Concrete piles and anti-seepage walls are installed in the deep overburden to support the concrete dam sections. This invention has the advantages of light weight, small cross-sectional dimensions, good economic efficiency, and low construction difficulty, making it suitable for use in conditions with restricted terrain conditions.

Description

Technical Field

[0001] The invention relates to water conservancy projects, and in particular to a deep overburden pile foundation concrete composite dam structure and a construction method thereof. Background Art

[0002] According to statistics, reservoirs in my country's plains are either built in low-lying areas, as part of plain river channels, or even at the boundaries of flood detention areas. The soil structure in these areas is loose, with low strength and high compressibility. Dams built in these areas often suffer from engineering geological problems such as dam foundation stability, dam foundation leakage, and dam foundation seismic liquefaction. Currently, earth-rock dams used in water conservancy project construction are mainly gravity dams such as traditional slope-type face dams and core wall dams. Due to the slope, this type of dam requires a larger site for construction and must be constructed with heavy materials such as rockfill. The dam body is heavy, so when the geological conditions are poor and the terrain conditions are limited, this type of dam is often ineffective and expensive.

[0003] For example, in the known technical solutions for building dam bodies on thick overburden,

[0004] CN104389294A discloses a panel rockfill dam on a thick overburden, and CN102852121A discloses an artificial composite foundation for a clay rockfill dam on a thick overburden. Both patent solutions fail to take into account the problem that the rockfill dam itself has a large gravity, while the thick overburden has a low bearing capacity and is prone to deformation.

[0005] In view of this, it is urgent to propose a dam type that can be built on limited terrain and on a deep overburden with poor mechanical properties, so as to solve the current urgent problem of water conservancy project construction in plain areas. Summary of the Invention

[0006] Objective of the Invention: To overcome the problems of poor soil properties, low bearing capacity, and limited site space in deep overburden, this invention provides a pile-foundation concrete composite dam structure with a low deadweight and strong adaptability to terrain. The invention also provides a construction method for this pile-foundation concrete composite dam structure.

[0007] Technical solution: The first aspect of the present invention provides a deep covering pile foundation concrete composite dam structure, including several hollow concrete dam sections, the upstream slope angle of the concrete dam section is 50°~80°, and the downstream slope angle is 80°~90°; rubber pads are arranged at the connecting parts between the concrete dam sections, and are connected through dampers; the dampers are arranged in the cavities of the concrete dam sections; concrete piles and anti-seepage walls are arranged in the deep covering layer to support the concrete dam sections.

[0008] The dam structure in the present invention is hollow and has a light deadweight. It can be built on a deep covering layer with poor mechanical properties. It uses less concrete and is economical. The damper is installed inside the concrete dam, which can effectively utilize the hollow structure. In addition, the combined use of the dam body with the pile foundation and the anti-seepage wall improves the applicable working conditions of this dam type. At the same time, the dam body has a steep slope and a small cross-sectional size, so it can be used under conditions with limited terrain conditions and has low construction difficulty.

[0009] Furthermore, due to the large differences in stiffness of different structural materials of the dam foundation and dam body, if the connection between different structural materials is not handled properly, it will also affect the stability of the dam body.

[0010] To this end, the concrete piles and the cut-off wall are connected to the concrete dam section bottom plate through flexible joints.

[0011] The concrete pile heads, the top of the anti-seepage wall and the concrete dam section bottom plate are connected by enlarged-head flexible joints. The existence of the flexible joint can effectively eliminate the effect of force and prevent shearing at the pile ends.

[0012] Furthermore, the concrete pile heads and the tops of the anti-seepage walls are embedded in the concrete dam section bottom plate, and the flexible joints are composed of low-foam plastic boards and flexible waterproof fillers, presenting an enlarged head structure.

[0013] Furthermore, the length of the concrete pile head embedded in the concrete dam section bottom plate is not less than 0.10m; the length of the top of the anti-seepage wall embedded in the concrete dam section bottom plate is 0.15 to 0.30m.

[0014] Furthermore, the above-mentioned deep cover pile foundation concrete composite dam structure also includes a bottom plate anti-de-airing device, which includes a flexible airbag and an air pressure control device; the flexible airbag is arranged at the bottom of the bottom plate of the concrete dam section, and the air pressure control device is arranged in the cavity of the concrete dam section; the air pressure control device is connected to the air injection port on the flexible airbag, which is used to evacuate and automatically replenish the pressure of the flexible airbag; the flexible airbag is also connected to a grouting pipe.

[0015] The bottom plate anti-cavitation device proposed in this technical solution can provide a responsive remedial solution for the subsequent uneven settlement of the dam body; installing the bottom plate anti-cavitation device inside the concrete dam can maximize the utilization of the hollow structure.

[0016] Furthermore, the volume of the flexible airbag is 0.8 to 1.5 m 3 , can withstand 0.15 ~ 0.25Mpa pressure.

[0017] Furthermore, a rockfill behind the dam is provided downstream of the concrete dam section, and the rockfill behind the dam is used when it is necessary to withstand a larger horizontal load.

[0018] Furthermore, the height of the rockfill behind the dam is 1 / 4 to 1 / 2 of the height of the concrete dam section, and the width is 1 / 6 to 5 / 8 of the width of the concrete dam section.

[0019] A second aspect of the present invention provides a construction method for a deep overburden pile foundation concrete composite dam structure, comprising the following steps:

[0020] (1) Exploring the topography and geological conditions at the dam site and determining the thickness of the deep overburden;

[0021] (2) Level the site and reinforce the surface soft soil to ensure that its bearing capacity can meet the requirements of pile foundation construction;

[0022] (3) Carry out the construction of concrete piles and anti-seepage walls, and connect the concrete pile heads and the top of the anti-seepage wall to the concrete dam section bottom plate using an enlarged head flexible joint;

[0023] (4) Arrange the flexible airbag and grouting pipe, connect the top of the flexible airbag to the bottom plate of the concrete dam section, and set the initial air pressure at 0.15-0.25 MPa; carry out the concrete dam section construction, and set the rubber cushion layer at the connection between the concrete dam sections; after the construction is completed, install the damper and air pressure control device;

[0024] (5) Setting up rockfill behind the concrete dam section;

[0025] (6) Construction quality inspection: open the air pressure control device and automatically pressurize the flexible airbag when the air pressure decreases; during the normal operation of the dam, when the volume of the flexible airbag reaches 0.8-1.5m 3 When the air is exhausted, the flexible air bag is evacuated; after the air is exhausted, grouting is performed through the grouting pipe; after the grouting is completed, the flexible air bag is inflated until the air pressure reaches the initial pressure, and then the inflation is stopped.

[0026] As mentioned above, the present invention has low construction difficulty, and the constructed deep cover pile foundation concrete composite dam structure has the aforementioned beneficial effects.

[0027] Furthermore, after the construction of the flexible joint is completed, the flexible joint is coated with concrete to facilitate the subsequent construction of the concrete dam section.

[0028] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: light weight, small cross-sectional size, good economy, low construction difficulty, and can be used in conditions with restricted terrain conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments of the present invention. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0030] Figure 1 It is a structural schematic diagram of the present invention;

[0031] Figure 2 It is a schematic diagram of the connection structure between concrete dam sections;

[0032] Figure 3 It is a schematic diagram of the connection structure between the concrete piles and the concrete dam section;

[0033] Figure 4 It is a schematic diagram of the connection structure between the cut-off wall and the concrete dam section;

[0034] Figure numerals: 1, concrete dam section; 2, deep cover layer; 3, concrete pile; 4, anti-seepage wall; 5, damper; 6, rockfill behind the dam; 7, flexible joint; 8, low-foam plastic board; 9, flexible waterproof filler; 10, rubber cushion; 11, bottom plate anti-emptying device; 12, flexible air bag; 13, grouting pipe; 14, air pressure control equipment; 15, air injection port. DETAILED DESCRIPTION

[0035] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are not exhaustive. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative work shall fall within the scope of protection of the present invention.

[0036] like Figure 1 and Figure 2 The figure shows a deep overburden pile-foundation concrete composite dam structure. The main structure consists of several concrete dam sections 1, which are installed on a deep overburden 2. Concrete piles 3 and cutoff walls 4 are installed in the deep overburden 2 to support the concrete dam sections 1. The cutoff wall 4 is located on the upstream side of the dam. When the project needs to withstand large horizontal loads, a backfill rockfill 6 is installed downstream of the concrete dam section 1. The backfill rockfill 6 has a height of 1 / 4 to 1 / 2 of the height of the concrete dam section 1 and a width of 1 / 6 to 5 / 8 of the width of the concrete dam section 1.

[0037] Concrete dam section 1 is a cast-in-place concrete structure. The dam height does not exceed 30 meters, and the width of the dam bottom plate ranges from 20 to 50 meters. The downstream extension of the concrete dam section 1 bottom plate is 1 / 6 to 1 / 4 of the dam height. The top width of concrete dam section 1 is not less than 4.0 meters, with the upstream concrete panel angle being 50° to 80° and the downstream concrete panel angle being 80° to 90°. Concrete dam section 1 is hollow internally, with a hollowness ratio of 35% to 60%. Reinforcing ribs are installed perpendicular to the dam axis. The length of concrete dam section 1 is 1.0 to 2.5 times its height. The joints between concrete dam sections 1 are filled with a rubber cushion layer 10 with a thickness of 5 to 10 cm.

[0038] A damper 5 and a bottom plate anti-cavitation device 11 are arranged on the bottom plate of the concrete dam section 1 and in the cavity of the concrete dam section 1. The damper 5 connects adjacent concrete dam sections 1.

[0039] The bottom plate anti-emptying device 11 consists of a flexible air bag 12, a grouting pipe 13 and an air pressure control device 14. The top of the flexible air bag 12 is connected to the bottom plate of the concrete dam section 1, and its volume is 0.8 to 1.5 m 3 The air pressure control device 14 is connected to the air injection port 15 on the flexible airbag 12, which can evacuate air and automatically replenish the pressure of the flexible airbag 12. The flexible airbag 12 is also connected to a grouting pipe 13.

[0040] The diameter of the concrete pile 3 is 0.6 to 1.5 m, and the thickness of the anti-seepage wall 4 is 0.6 to 1.0 m. Figure 3 and Figure 4 As shown, the concrete piles 3 and the cutoff wall 4 are each connected to the concrete dam section 1 floor via flexible joints 7. The flexible joints 7 are enlarged head structures composed of low-foam plastic sheets 8 and waterproof fillers 9. The top of the concrete piles 3 is embedded in the concrete dam section 1 floor for at least 0.10 m; the top of the cutoff wall 4 is embedded in the concrete dam section 1 floor for 0.15 to 0.30 m.

[0041] Low-foam plastic sheets 8 are placed on both sides of the concrete pile 3 where the head is embedded in the baseplate. The thickness is 1 / 5 to 1 / 3 of the pile diameter. Flexible waterproof filler 9 is applied from the bottom of the low-foam plastic sheets 8 in the shape of an enlarged head. The top width of the flexible waterproof filler 9 is 1 to 1.4 times the diameter of the concrete pile 3, and the total height is 1 / 2 to 1 / 3 of the concrete pile 3.

[0042] Low-foam plastic sheets 8 are placed on both sides of the top of the cutoff wall 4, extending along the length of the embedded base plate. The thickness is 1 / 5 to 1 / 3 of the wall's thickness. Flexible waterproof filler 9 is applied from the bottom of the low-foam plastic sheets 8 in the shape of an enlarged head. The top width of the flexible waterproof filler 9 is 1 to 1.4 times the wall's thickness, and the total height is 1 / 2 to 1 / 3 of the wall's thickness.

[0043] A construction method for a deep overburden pile foundation concrete composite dam structure comprises the following steps:

[0044] (1) Exploring the topography and geological conditions at the dam site and determining the thickness of the deep overburden layer 2;

[0045] (2) Level the site and reinforce the surface soft soil to ensure that its bearing capacity can meet the requirements of pile foundation construction;

[0046] (3) Construct the concrete piles 3 and the cut-off wall 4. Connect the pile heads of the concrete piles 3 and the tops of the cut-off wall 4 to the bottom plate of the concrete dam section 1 using an enlarged-head flexible joint 7. After the flexible joint 7 is constructed, smear the flexible joint 7 with concrete to facilitate the subsequent construction of the concrete dam section 1.

[0047] (4) Arrange the flexible airbag 12 and the grouting pipe 13. The top of the flexible airbag 12 is connected to the bottom plate of the concrete dam section 1. The initial air pressure is 0.15-0.25 MPa. The concrete dam section 1 is constructed. The rubber cushion layer 10 is installed at the connection between the concrete dam sections 1. After the construction is completed, the damper 5 and the air pressure control device 14 are installed.

[0048] (5) Setting up a rockfill 6 behind the concrete dam section 1;

[0049] (6) Construction quality inspection: open the air pressure control device 14, and automatically pressurize the flexible airbag 12 when the air pressure decreases; during the normal operation of the dam body, when the volume of the flexible airbag 12 reaches 0.8-1.5m 3 After the air is exhausted, grouting is performed through the grouting pipe 13; after the grouting is completed, the flexible air bag 12 is inflated until the air pressure reaches the initial pressure, and then the inflation is stopped.

[0050] A specific example is given below.

[0051] Concrete dam section 1 is 14m high and has a base plate width of 21.5m. The upper and lower reaches of the concrete dam section 1 extend 3.0m and are 2.5m wide. The top of the concrete base plate 5 is flush with the ground level. The dam body is 6.0m wide at the top. The upstream concrete surface angle is 50°, while the downstream concrete surface angle is 90°. Reinforcement ribs are installed perpendicular to the dam axis. The dam body has a hollow ratio of 53%. Concrete piles 3 are 30m long and 0.8m in diameter. Their bases are embedded in the harder soil. Flexible joints 7 are used at the top to connect to the concrete base plate 5. Low-foam plastic sheets 8, each 0.16m thick, are placed on both sides of the length of the concrete piles 3 embedded in the base plate. A flexible waterproof filler 9 (such as mastic asphalt) is applied to the low-foam plastic sheets 8 and the tops of the concrete piles 3, forming an inverted trapezoidal structure with a height of 0.16m. The tops are embedded in the concrete base plate 5 for a length of 0.2m. The anti-seepage wall 4 is 10m long and 0.8m thick, with its top embedded in a concrete slab 5 for a length of 0.2m. Flexible joints 7 are used between the top and the concrete slab 5. Specifically, low-foam plastic sheets 8, 0.16m thick, are placed on both sides of the cutoff wall 4 where it is embedded in the slab. A flexible waterproof filler 9 (such as mastic asphalt) is applied to the low-foam plastic sheets 8 and the top of the anti-seepage wall 4 to form an inverted trapezoidal structure with a height of 0.16m. The rockfill 6 behind the dam has a loading height of 4m and a width of 6m. The concrete dam section 1 is 20m long, with a 0.1m thick cushion layer 10 between adjacent sections. A damper 5 is placed on each side of the hollow slab of the concrete dam section 1, upstream and downstream, and two slab anti-slip devices 11 are installed in each concrete dam section 1.

[0052] The construction method of the deep overburden pile foundation concrete rockfill composite dam structure comprises the following steps:

[0053] (1) Based on the on-site topography and geological conditions, the thickness of the deep overburden 2 at the dam site is 35 m.

[0054] (2) The site was leveled and the surface soft soil at the location of the concrete dam section 1 was reinforced to ensure that its bearing capacity met the requirements of pile foundation construction.

[0055] (3) Construction of the concrete piles 3 and the cutoff wall 4 is carried out. The pile heads of the concrete piles 3 and the top of the cutoff wall 4 are connected to the concrete dam section 1 base plate using an enlarged-head flexible joint 7. After the flexible joint 7 is constructed, it is coated with concrete to facilitate the subsequent construction of the concrete dam section 4.

[0056] (4) Arrange the grouting pipe 13 and flexible airbag 12. The top of the flexible airbag 12 is connected to the bottom plate of the concrete dam section 1. The initial air pressure is 0.15-0.25 MPa and the thickness is very small. The concrete dam section 1 is constructed, and a rubber cushion layer 10 with a thickness of 5-10 cm is installed at each dam section connection. After construction is completed, the damper 5 and air pressure control device 14 are installed.

[0057] (5) A rockfill 6 is set up behind the dam downstream of the concrete dam section 1.

[0058] (6) Construction quality inspection. Open the air pressure control device 14, and automatically pressurize the flexible airbag 12 when the air pressure decreases. During the normal operation of the dam body, when the volume of the flexible airbag 12 reaches 0.8 to 1.5 m 3 When the flexible air bag 12 is exhausted, the grouting pipe 13 is opened and grouting is performed. After grouting is performed, the flexible air bag 12 is inflated to the point where the air pressure reaches the initial air pressure and then stops inflating.

[0059] 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 modifications or alternatives that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention are intended to be covered by the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be subject to the scope of protection of the claims.

Claims

1. A deep overburden pile foundation concrete composite dam structure, characterized in that: The invention comprises a plurality of hollow concrete dam sections (1), wherein the upstream slope angle of the concrete dam sections (1) is 50° to 80° and the downstream slope angle is 80° to 90°; a rubber cushion layer (10) is provided at the connection between the concrete dam sections (1) and the sections are connected via a damper (5); the damper (5) is provided in the cavity of the concrete dam section (1); and concrete piles (3) and an anti-seepage wall (4) are provided in the deep cover layer (2) to support the concrete dam section (1); The concrete pile (3) and the anti-seepage wall (4) are respectively connected to the bottom plate of the concrete dam section (1) through a flexible joint (7); the pile head of the concrete pile (3) and the top of the anti-seepage wall (4) are embedded in the bottom plate of the concrete dam section (1), and the flexible joint (7) is composed of a low-foaming plastic board (8) and a flexible waterproof filler (9), and is in an enlarged head type structure; The deep overburden pile foundation concrete composite dam structure further comprises a bottom plate anti-de-airing device (11), the bottom plate anti-de-airing device (11) comprising a flexible air bag (12) and an air pressure control device (14); the flexible air bag (12) is arranged at the bottom of the bottom plate of the concrete dam section (1), and the air pressure control device (14) is arranged in the cavity of the concrete dam section (1); the air pressure control device (14) is connected to the air injection port (15) on the flexible air bag (12) and is used for evacuating air from the flexible air bag (12) and automatically replenishing pressure; the flexible air bag (12) is also connected to a grouting pipe (13).

2. The deep overburden pile foundation concrete composite dam structure according to claim 1 is characterized in that: The length of the pile head of the concrete pile (3) embedded in the bottom plate of the concrete dam section (1) is not less than 0.10m; the length of the top of the anti-seepage wall (4) embedded in the bottom plate of the concrete dam section (1) is 0.15~0.30m.

3. The deep overburden pile foundation concrete composite dam structure according to claim 1, characterized in that: The volume of the flexible airbag (12) is 0.8~1.5m 3 , can withstand 0.15~0.25Mpa pressure.

4. The deep overburden pile foundation concrete composite dam structure according to claim 1, characterized in that: A rockfill (6) is provided downstream of the concrete dam section (1).

5. The deep overburden pile foundation concrete composite dam structure according to claim 4, characterized in that: The height of the rockfill (6) behind the dam is 1 / 4 to 1 / 2 of the height of the concrete dam section (1), and the width is 1 / 6 to 5 / 8 of the width of the concrete dam section (1).

6. A construction method for a deep overburden pile foundation concrete composite dam structure according to claim 4, characterized in that: The steps include: (1) Exploring the topography and geological conditions at the dam site and determining the thickness of the deep overburden (2); (2) Level the site and reinforce the surface soft soil to ensure that its bearing capacity can meet the requirements of pile foundation construction; (3) constructing the concrete piles (3) and the anti-seepage wall (4), and connecting the pile heads of the concrete piles (3) and the tops of the anti-seepage wall (4) to the bottom plate of the concrete dam section (1) using an enlarged head type flexible joint (7); (4) Arranging the flexible airbag (12) and the grouting pipe (13), with the top of the flexible airbag (12) connected to the bottom plate of the concrete dam section (1), with the initial air pressure being 0.15-0.25 MPa; constructing the concrete dam section (1), and setting a rubber cushion layer (10) at the connection between the concrete dam sections (1); after the construction is completed, installing the damper (5) and the air pressure control device (14); (5) Setting up a rockfill (6) behind the concrete dam section (1); (6) Construction quality inspection: open the air pressure control device (14) and automatically pressurize the flexible air bag (12) when the air pressure decreases; during the normal operation of the dam body, when the volume of the flexible air bag (12) reaches 0.8~1.5m 3 When the air is exhausted, the flexible air bag (12) is evacuated; after the air is exhausted, grouting is performed through the grouting pipe (13); after the grouting is completed, the flexible air bag (12) is inflated until the air pressure reaches the initial air pressure, and then the inflation is stopped.

7. The construction method according to claim 6, characterized in that: After the flexible joint (7) is constructed, the flexible joint (7) is coated with concrete to facilitate the subsequent construction of the concrete dam section (1).

Images