Panel rockfill dam foundation drainage structure and construction method thereof

Abstract

The application discloses a kind of face plate rock-fill dam foundation drainage structure and its construction method, it is related to drainage structure technical field, including face plate rock-fill dam, drainage hole is opened in the foundation of face plate rock-fill dam, the in-hole mouth outside of drainage hole is provided with reinforced stone cage, the in-hole mouth inside of drainage hole is provided with concrete retaining wall, and concrete toe plate is arranged on face plate rock-fill dam.The application sets up foundation drainage structure in the range of face plate rock-fill dam foundation in the higher topography of concrete toe plate downstream, drains dam seepage water, avoids the possibility that face plate bottom generates reverse water pressure, influences safety;Drainage hole is constructed together during dam foundation excavation by drilling and blasting method, and construction is convenient, and drainage hole outlet is located in dam downstream, and road or inspection passage can be directly set, and daily maintenance personnel can conveniently enter and exit;Drainage hole structure discharge capacity is large, and it is not easy to block, and dam seepage water can be effectively drained, so as to reduce the reverse water pressure that face plate bears.

Description

Technical Field

[0001] This invention relates to the field of drainage structure technology, and in particular to a drainage structure for a panel rockfill dam foundation and its construction method. Background Technology

[0002] In hydropower and water conservancy projects, rockfill dams with concrete panels are a common type of dam. After the foundation is excavated, the terrain downstream of the toe slab of the rockfill dam with concrete panels is generally higher than the foundation elevation of the toe slab, which leads to poor drainage of the foundation. Rainfall during construction, water used during construction, and seepage during operation can create reverse water pressure on the concrete panel, which may lead to damage to the concrete panel and project failure.

[0003] Most rockfill dams with concrete panels are located in riverbeds or valleys, where the downstream terrain is only slightly higher than the toe slab. During the construction phase, reverse drainage structures or drainage channels can be used to address this issue. Before impounding water, the reverse drainage structures are sealed off, and the drainage channels can continue to be used for drainage during the operation phase. During the operation phase, drainage channels excavated during the construction phase can be used to continue drainage. Alternatively, considering that the downstream terrain is only slightly higher than the toe slab and that the backfilled rock slag upstream of the concrete panel can effectively level the surface, no special foundation drainage measures are required during the operation phase.

[0004] Due to topographical reasons, some existing projects require the construction of secondary dams on the reservoir bank. The toe slab is much higher than the toe slab foundation, making the excavation of drainage channels difficult and costly. Furthermore, due to the large topographical difference, the reverse water pressure acting on the panel during a sudden drop in water level during operation cannot be effectively balanced by backfilling with stone slag, resulting in a high risk of panel damage. Summary of the Invention

[0005] To address the aforementioned issues in existing projects where secondary dams are required on the reservoir bank due to topographical reasons, the toe slab is significantly higher than the toe slab foundation, making drainage ditch excavation difficult and costly, and the large elevation difference means that the reverse water pressure acting on the panel during a sudden drop in water level cannot be effectively balanced by backfilling with rockfill, posing a high risk of panel damage, this invention provides a panel rockfill dam foundation drainage structure and its construction method.

[0006] This invention provides a drainage structure for a panel rockfill dam foundation, employing the following technical solution:

[0007] A drainage structure for a panel rockfill dam foundation includes a panel rockfill dam, a drainage hole is provided in the foundation of the panel rockfill dam, a reinforced gabion is provided on the outside of the inlet of the drainage hole, a concrete retaining wall is provided on the inside of the inlet of the drainage hole, a concrete toe slab is provided on the panel rockfill dam, and a curtain grouting is provided below the concrete toe slab.

[0008] Optionally, in the above-mentioned drainage structure for a panel rockfill dam foundation, the upstream side of the panel rockfill dam is backfilled with stone chips.

[0009] Optionally, in the above-mentioned drainage structure for a panel rockfill dam foundation, the diameter of the drainage tunnel is 3m, and the perimeter of the drainage tunnel is lined with C25 concrete with a thickness of 30cm.

[0010] Optionally, in the above-mentioned drainage structure for a panel rockfill dam foundation, the longitudinal slope of the bottom slab of the drainage tunnel is 5%.

[0011] Optionally, in the above-mentioned drainage structure for a panel rockfill dam foundation, the length, height, and width of the reinforced gabion are all 100cm, and the interior of the reinforced gabion is filled with pebbles with a particle size of 8-20cm.

[0012] Optionally, in the above-mentioned drainage structure for a panel rockfill dam foundation, the concrete retaining wall is a C20 concrete structure, and the height of the concrete retaining wall is the same as the height of the drainage hole.

[0013] Optionally, in the above-mentioned drainage structure for a rockfill dam foundation, the concrete retaining wall adopts a gravity concrete wall structure, the top width of the concrete retaining wall is 1m, the upstream face is vertical, and the downstream face is 1:0.5.

[0014] Optionally, in the above-mentioned drainage structure for a panel rockfill dam foundation, drainage holes are provided on the concrete retaining wall, and the diameter of the drainage holes is 50cm.

[0015] Another technical solution proposed in this invention: a construction method for a drainage structure for a rockfill dam foundation, comprising the following steps:

[0016] S101: Construction of drainage tunnel;

[0017] The drainage tunnel was constructed using the conventional drill and blast method. The tunnel diameter was 3m, and the tunnel perimeter was lined with concrete. The support parameters for the drainage tunnel were configured based on the surrounding rock type and calculation results.

[0018] S102: Construction of concrete retaining walls;

[0019] A concrete retaining wall structure is constructed inside the inlet of the drainage tunnel. The concrete retaining wall adopts a gravity concrete retaining wall structure. Drainage holes are then opened on the concrete retaining wall. The concrete retaining wall is formed by casting in place with the formwork, and its reinforcement is configured according to the structural requirements.

[0020] S103: Construction of reinforced gabion cages;

[0021] The steel gabions were neatly stacked on the outside of the drainage tunnel entrance.

[0022] In summary, the present invention has at least one of the following beneficial effects:

[0023] A foundation drainage structure is installed within the foundation area of ​​the rockfill dam with a higher terrain downstream of the concrete toe slab to drain the dam seepage and avoid the possibility of reverse water pressure at the bottom of the slab affecting safety.

[0024] The drainage tunnel was constructed using the drill-and-blast method during the dam foundation excavation, which was convenient. Furthermore, the drainage tunnel outlet is located downstream of the dam, allowing for direct access via roads or inspection channels, making it easy for daily maintenance personnel to enter and exit.

[0025] The drainage tunnel structure has a large discharge capacity and is not easily blocked, which can effectively drain the dam seepage water, thereby reducing the reverse water pressure on the dam face. Attached Figure Description

[0026] Figure 1 This is a longitudinal section view of the stone dam drainage tunnel of the present invention;

[0027] Figure 2 This is a schematic diagram of the cross-section of the concrete retaining wall of the present invention;

[0028] Figure 3 This is a three-dimensional structural schematic diagram of the reinforced gabion of the present invention.

[0029] In the diagram: 1. Panel rockfill dam; 2. Drainage tunnel; 3. Reinforced gabion; 4. Concrete retaining wall; 5. Concrete toe slab; 6. Curtain grouting; 7. Stone backfill; 8. Pebbles; 9. Drainage hole. Detailed Implementation

[0030] The following is in conjunction with the appendix Figure 1-3 The present invention will be described in further detail below.

[0031] Please refer to the attached diagram in the instruction manual. Figure 1 , Figure 2 and Figure 3 The present invention provides an embodiment of a panel rockfill dam foundation drainage structure, comprising a panel rockfill dam 1, wherein a stone backfill 7 is laid upstream of the panel rockfill dam 1.

[0032] Drainage tunnel 2 is constructed within the foundation of the rockfill dam 1. The drainage tunnel is constructed using the drill-and-blast method during the excavation of the dam foundation. The diameter of drainage tunnel 2 is 3m. The perimeter of drainage tunnel 2 is lined with 30cm thick C25 concrete. The longitudinal slope of the bottom slab of drainage tunnel 2 is 5%. Lining the perimeter of drainage tunnel 2 with a 30cm thick layer of C25 concrete increases the stability and drainage effect of drainage tunnel 2, and also facilitates operator access to drainage tunnel 2 for maintenance.

[0033] A reinforced gabion 3 is installed on the outside of the entrance of drainage tunnel 2. The length, height and width of the reinforced gabion 3 are all 100cm. The interior of the reinforced gabion 3 is filled with pebbles 8 with a particle size of 8-20cm. The reinforced gabion 3 is neatly stacked upstream of the entrance of drainage tunnel 2 to filter the drainage and prevent the possibility of dam filling stones entering drainage tunnel 2.

[0034] A concrete retaining wall 4 is installed inside the inlet of drainage tunnel 2. The concrete retaining wall 4 is a C20 concrete structure. The height of the concrete retaining wall 4 is the same as the height of drainage tunnel 2. The concrete retaining wall 4 adopts a gravity concrete wall structure. The top width of the concrete retaining wall 4 is 1m, and the upstream face is vertical and the downstream face is 1:0.5. Drainage holes 9 are provided on the concrete retaining wall 4. The diameter of the drainage holes 9 is 50cm. The concrete retaining wall can provide support for the dam's rockfill and reinforced gabion, and the drainage holes 9 are used to drain the dam's seepage water.

[0035] A concrete toe slab 5 is installed on the rockfill dam 1 with a concrete face panel. A foundation drainage structure is set within the foundation area of ​​the rockfill dam 1 with higher terrain downstream of the concrete toe slab 5 to drain the seepage water of the dam and avoid the possibility of reverse water pressure at the bottom of the face panel, which may affect safety. The concrete toe slab 5 is connected to the face panel by a perimeter joint with water-stopping features, forming a seepage barrier above the dam foundation. At the same time, it is connected to the bedrock after foundation treatment, sealing the seepage channels below the ground. Thus, the upper and lower seepage barrier structures are connected as a whole. In addition to seepage prevention, its main function is to serve as a cover for foundation grouting and a base for the face panel.

[0036] A curtain grouting 6 is installed below the concrete toe slab 5. The curtain grouting 6 is a grouting project that injects grout into the cracks and pores of the rock mass or soil layer to form a continuous water-blocking curtain, thereby reducing the seepage flow and reducing the seepage pressure. The curtain grouting 6 facilitates the reduction of the seepage flow of the rock dam.

[0037] To better demonstrate a drainage structure for a rockfill dam foundation, this embodiment presents a construction method for such a structure, comprising the following steps:

[0038] Step 1: Construction of drainage hole 2;

[0039] Drainage Tunnel 2 is constructed using the conventional drill and blast method. To facilitate construction and maintenance, the diameter of the conventional tunnel section of Drainage Tunnel 2 can be 3m. The tunnel perimeter is lined with 30cm thick C25 concrete. The longitudinal slope of the bottom slab of Drainage Tunnel 2 is 5%. The support parameters are configured according to the surrounding rock type and calculation results.

[0040] Step 2, Construction of concrete retaining wall 4;

[0041] Then, a concrete retaining wall 4 is constructed inside the entrance of drainage tunnel 2. The concrete structure is C20 concrete, with a maximum height of 3m and consistent with the tunnel height. The concrete retaining wall 4 is a gravity-type concrete retaining wall structure with a top width of 1m, a vertical upstream face, and a 1:0.5 ratio downstream face. Drainage holes 9 are then opened on the concrete retaining wall 4. The concrete retaining wall 4 is formed by casting in place with the formwork, and its reinforcement is configured according to the structural requirements.

[0042] Step 3, Construction of reinforced gabion 3;

[0043] Finally, the steel gabion 3 is neatly stacked on the outside of the entrance of the drainage tunnel 2. The steel gabion 3 is prefabricated off-site or welded on-site, and filled with pebbles 8 with a particle size of 8-20cm.

[0044] The above are all preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape and principle of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A foundation drainage structure for a face-panel rockfill dam, comprising a face-panel rockfill dam (1), characterized in that: The foundation of the rockfill dam (1) has a drainage hole (2). A reinforced gabion (3) is installed on the outside of the inlet of the drainage hole (2). A concrete retaining wall (4) is installed on the inside of the inlet of the drainage hole (2). A concrete toe slab (5) is installed on the rockfill dam (1). A curtain grout (6) is installed below the concrete toe slab (5). The length, height and width of the reinforced gabion (3) are all 100cm. The reinforced gabion (3) is filled with pebbles (8). The particle size of the pebbles (8) is 8-20cm. The concrete retaining wall (4) is a C20 concrete structure. The height of the concrete retaining wall (4) is the same as the height of the drainage hole (2). Drainage holes (9) are provided on the wall of the concrete retaining wall (4). The diameter of the drainage holes (9) is 50cm.

2. The drainage structure for a panel rockfill dam foundation according to claim 1, characterized in that: Upstream of the panel rockfill dam (1), stone backfill (7) is laid.

3. The drainage structure for the foundation of a rockfill dam according to claim 1, characterized in that: The drainage hole (2) has a diameter of 3m, and the drainage hole (2) is lined with C25 concrete with a thickness of 30cm.

4. The drainage structure for the foundation of a rockfill dam according to claim 3, characterized in that: The longitudinal slope of the bottom slab of the drainage tunnel (2) is 5%.

5. The drainage structure for a panel rockfill dam foundation according to claim 1, characterized in that: The concrete retaining wall (4) adopts a gravity-type concrete wall structure. The top width of the concrete retaining wall (4) is 1m, and the upstream face is vertical and the downstream face is 1:0.

5.

6. A construction method for a drainage structure for a rockfill dam foundation as described in any one of claims 1-5, comprising the following steps: S101: Construction of drainage tunnel (2); The drainage tunnel (2) was constructed using conventional drilling and blasting methods. The tunnel diameter was 3m, and the tunnel perimeter was lined with concrete. The support parameters of the drainage tunnel (2) were configured according to the surrounding rock type and calculation results. S102: Construction of concrete retaining wall (4); Concrete retaining wall (4) is constructed inside the entrance of drainage hole (2). The concrete retaining wall (4) adopts a gravity concrete retaining wall structure. Then, drainage holes (9) are opened on the wall of the concrete retaining wall (4). The concrete retaining wall (4) is formed by casting in place and its reinforcement is configured according to the structural requirements. S103: Construction of reinforced gabion (3); The steel gabion (3) is neatly stacked on the outside of the entrance of the drainage hole (2).

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