A water and electricity engineering ditch type debris flow prevention system

Abstract

The application discloses a water and electricity engineering ditch type debris flow prevention system and belongs to the technical field of water and electricity and water conservancy. The system comprises a drainage mechanism, a construction site, a soil and rock dam, a silt stopping pool and a plurality of flexible dams which are sequentially arranged in a ditch from a downstream to an upstream, and the upstream end of the drainage mechanism is communicated with the silt stopping pool after penetrating through the soil and rock dam, the middle part is buried in the construction site, and the downstream end extends to the downstream of the construction site. The drainage mechanism is arranged to drain the debris flow, so as to replace the drainage groove in the prior art. The drainage mechanism is buried, the geological condition requirement of the foundation is low, the engineering quantity is small, the investment is low, and the construction period is short.

Description

Technical Field

[0001] This invention relates to a channel-type debris flow prevention system for hydropower projects, belonging to the field of hydropower and water conservancy technology. Background Technology

[0002] Currently, most of my country's hydropower and water conservancy projects are concentrated in the high mountain and canyon areas of Tibet. The geological conditions in this region are complex and the construction site layout is tight. Many construction sites are located in the gullies on both sides of the river. Most of the gullies in Tibet are debris flow gullies. Debris flows are characterized by suddenness, high velocity, large flow, large material capacity and strong destructive power, which have a significant impact on the layout of construction sites.

[0003] Chinese patent document CN107119624A discloses a prevention and control system for a large spoil heap within a debris flow gully. The system includes a spoil heap, a dam, a sediment retention area, a drainage channel, and a retaining embankment. The dam is located upstream of the debris flow gully, and the sediment retention area is located between the dam and a downstream retaining embankment. The drainage channel is located on one side of the spoil heap and is arranged along its edge. The inlet of the drainage channel is located upstream of the top of the spoil heap, and the outlet is located outside the top of the spoil heap. The inlet of the drainage channel is located on one side of the retaining embankment and is interrupted by the retaining embankment. This system ensures that the debris flow can smoothly pass through the spoil heap and be discharged to a safe location, thereby guaranteeing the stability and safety of the spoil heap.

[0004] However, the drainage channels of the above-mentioned prevention and control system are located on one side of the spoil disposal site and arranged along the edge of the spoil disposal site. The excavation, concrete pouring and support of the drainage channels involve a large amount of work, high investment, long construction period and high requirements for the foundation. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a hydropower engineering channel-type debris flow prevention system.

[0006] This invention is achieved through the following technical solution:

[0007] A hydropower engineering channel-type debris flow prevention system includes a drainage mechanism, and a construction site, an earth-rock dam, a sedimentation pond, and several flexible dams arranged sequentially from downstream to upstream within the channel. The upstream end of the drainage mechanism passes through the earth-rock dam and connects to the sedimentation pond, the middle part is buried in the construction site, and the downstream end extends to the downstream of the construction site.

[0008] The upstream section of the bottom surface of the silt-retention pond is excavated as a gentle slope with a longitudinal slope of no more than 10%, while the downstream section of the bottom surface of the silt-retention pond is excavated as a stepped structure.

[0009] Each platform in the downstream section of the bottom surface of the silt-retention pool is inclined downward relative to the downstream section at its upstream end in the longitudinal direction of the channel.

[0010] The earth-rock dam is equipped with a seepage prevention mechanism on its water-facing surface.

[0011] The seepage prevention mechanism includes a geomembrane and a concrete cutoff wall. The geomembrane is located on the upper part of the water-facing side of the earth-rock dam, and the concrete cutoff wall is located on the lower part of the water-facing side of the earth-rock dam and is connected to the geomembrane. The bottom of the concrete cutoff wall is connected to a seepage prevention curtain that extends into the foundation.

[0012] The lower part of the water-facing side of the earth-rock dam is equipped with a trash rack, which is made of multiple 20b type I-beams welded together, and the spacing between the rows of 20b type I-beams is no more than 1m.

[0013] The inlet of the discharge mechanism is located inside the trash rack.

[0014] The drainage mechanism includes a corrugated steel pipe, and the inlet, outlet and bend of the corrugated steel pipe are fixed by piers.

[0015] It also includes an emergency drainage mechanism, the upstream end of which passes through the earth-rock dam and exits from the upper part of the water-facing side of the earth-rock dam to connect with the silt retention pool, and the downstream end of the emergency drainage mechanism is connected to the middle part of the drainage mechanism.

[0016] The emergency drainage mechanism includes an emergency corrugated steel pipe, the downstream end of which is connected to the middle part of the drainage mechanism via a tee.

[0017] The tee is fixed by a retaining block.

[0018] The beneficial effects of this invention are as follows:

[0019] 1. A drainage mechanism is set up to drain debris flows, replacing the drainage channel in the existing technology. The drainage mechanism has low requirements for the geological conditions of the foundation, small amount of engineering work, low investment, and short construction period.

[0020] 2. First, large rocks and trees in the ditch are intercepted by multiple flexible dams. Then, solid materials passing through the flexible dams are effectively intercepted by the sediment retention pond. The sediment retention pond can hold large rocks in the debris flow under the design standard. Then, the rocks are intercepted by the trash rack at the inlet of the corrugated steel pipe to ensure that the corrugated steel pipe is not blocked, thereby ensuring that the corrugated steel pipe can smoothly drain the debris flow.

[0021] 3. A sedimentation basin was installed upstream of the earth-rock dam, and an anti-seepage mechanism was installed on the water-facing side of the dam. An emergency corrugated steel pipe was installed at the top of the dam. When excessive debris flow blocks the corrugated steel pipe, the earth-rock dam acts as a retaining dam, blocking the solid material of the debris flow. At this time, the debris flow is discharged through the emergency corrugated steel pipe, thus achieving the prevention and control of excessive debris flow and further ensuring the safety of the construction site.

[0022] 4. By using the middle and downstream sections of the corrugated steel pipe in conjunction with the emergency corrugated steel pipe, the excess debris flow can be drained, making full use of the corrugated steel pipe instead of laying another pipe to work with the emergency corrugated steel pipe to drain the excess debris flow, thus reducing the amount of work and investment. Attached Figure Description

[0023] Figure 1 This is a plan view of the present invention;

[0024] Figure 2 This is a cross-sectional view of the invention along the longitudinal direction of the channel;

[0025] Figure 3 This is a schematic diagram of the structure of the present invention at an earth-rock dam.

[0026] Figure 4 This is a schematic diagram of the structure of the earth-rock dam facing the water in this invention;

[0027] Figure 5 This is a schematic diagram of the flexible water-retaining dam of the present invention;

[0028] Figure 6 This is an assembly drawing of the corrugated steel pipe, emergency corrugated steel pipe, tee, and anchor block of the present invention.

[0029] In the diagram: 1-Flexible dam, 2-Earth-rock dam, 3-Corrugated steel pipe, 4-Emergency corrugated steel pipe, 5-Tee, 6-Stabilizing pier, 7-Seepage barrier curtain, 8-Geomembrane, 9-Silt retention pond, 10-Concrete seepage barrier wall, 11-Trash rack, 12-Construction site, 13-Drainage mechanism. Detailed Implementation

[0030] The technical solution of the present invention is further described below, but the scope of protection is not limited to what is described.

[0031] Example 1:

[0032] Based on the scale of construction site 12, the design standards for debris flow prevention and control are determined, as well as the peak flow rate and total solid material volume of a single debris flow under the design standards.

[0033] like Figures 1 to 6 As shown, the present invention provides a hydropower engineering channel-type debris flow prevention system, which includes a drainage mechanism 13, and a construction site 12, an earth-rock dam 2, a sedimentation pond 9, and multiple flexible dams 1 arranged sequentially from downstream to upstream within the channel. The upstream end of the drainage mechanism 13 passes through the earth-rock dam 2 and connects with the sedimentation pond 9, the middle part is buried in the construction site 12, and the downstream end extends to the downstream of the construction site 12.

[0034] Flexible dam 1 and earth-rock dam are set up to block debris flow, replacing conventional rigid dams such as grid dams, sieve dams, comb dams, and permeable arch dams. This method has low requirements for the foundation, which can greatly reduce the amount of foundation excavation and support work, saving construction time and project investment. Then, a drainage mechanism 13 is set up to drain the debris flow, replacing the drainage channel in the existing technology. The drainage mechanism 13 has low requirements for the geological conditions of the foundation, small amount of engineering work, low investment, and short construction period.

[0035] The upstream section of the bottom surface of the siltation pond 9 is excavated as a gentle slope with a longitudinal slope of no more than 10%, and the downstream section of the bottom surface of the siltation pond 9 is excavated as a stepped shape.

[0036] The platforms on the downstream section of the bottom surface of the sedimentation tank 9 are inclined downwards relative to the downstream section at their upstream ends in the longitudinal direction of the channel. The sedimentation tank 9 can effectively intercept solid materials passing through the flexible barrier dam 1, can accommodate large rocks in debris flows under design standards, ensure that the corrugated steel pipe 3 is not blocked, and thus ensure that the corrugated steel pipe 3 can smoothly drain debris flows.

[0037] The earth-rock dam 2 is equipped with a seepage prevention mechanism on its water-facing surface.

[0038] The seepage prevention mechanism includes a geomembrane 8 and a concrete cutoff wall 10. The geomembrane 8 is located on the upper part of the water-facing side of the earth-rock dam 2, and the concrete cutoff wall 10 is located on the lower part of the water-facing side of the earth-rock dam 2 and connected to the geomembrane 8. A seepage prevention curtain 7 extending deep into the foundation is connected to the bottom of the concrete cutoff wall 10. By setting up the geomembrane 8, the concrete cutoff wall 10, and the seepage prevention curtain 7, the seepage stability of the earth-rock dam 2 and the construction site 12 is ensured.

[0039] The lower part of the water-facing side of the earth-rock dam 2 is equipped with a trash rack 11. The trash rack 11 is made of multiple 20b type I-beams welded together, and the spacing between the rows of 20b type I-beams is no more than 1m.

[0040] The inlet of the drainage mechanism 13 is located inside the debris barrier 11. The debris barrier 11 is installed at the inlet of the corrugated steel pipe 3 to intercept large stones, ensuring that the corrugated steel pipe 3 is not blocked, thereby ensuring that the corrugated steel pipe 3 can smoothly drain debris flow.

[0041] The drainage mechanism 13 includes a corrugated steel pipe 3, which is fixed at its inlet, outlet, and bends by anchor blocks 6. The corrugated steel pipe 3 is used to drain debris flows, and its fixation by the anchor blocks 6 ensures its stable and safe operation.

[0042] It also includes an emergency drainage mechanism. The upstream end of the emergency drainage mechanism passes through the earth-rock dam 2 and exits from the upper part of the water-facing side of the earth-rock dam 2 to connect with the silt retention pool 9. The downstream end of the emergency drainage mechanism is connected to the middle part of the drainage mechanism 13.

[0043] The emergency drainage mechanism includes an emergency corrugated steel pipe 4, the downstream end of which is connected to the middle of the drainage mechanism 13 via a tee 5. The downstream end of the emergency corrugated steel pipe 4 is also connected to the middle of the corrugated steel pipe 3 via a tee 5. The addition of the emergency corrugated steel pipe 4 ensures that even if the corrugated steel pipe 3 is blocked by excessive debris flow, the emergency corrugated steel pipe 4 can still effectively drain the debris flow, ensuring the safety and stability of the construction site 12. Connecting the corrugated steel pipe 3 and the emergency corrugated steel pipe 4 via the tee 5 optimizes the length of the emergency corrugated steel pipe 4, saving on project investment.

[0044] The tee 5 is fixed by the anchor block 6.

[0045] Example 2:

[0046] The aforementioned gully-type debris flow prevention system for hydropower projects has been used in some projects with good results. Implementation cases and processes are as follows:

[0047] This example uses the debris flow prevention and control of a gully in the RM project as a case study. The gully is a right-bank tributary of the Lancang River, characterized by deeply dissected, tectonically eroded, high-mountain terrain. The overall terrain within the watershed is steep, with numerous gullies and well-developed free-fall conditions, providing favorable conditions for the collection of loose solid debris for debris flows. The gully's catchment area is 40.75 km². 3 The main ditch is 13.01 km long with a relative elevation difference of 3092 m. The average longitudinal ratio of the main ditch is 19.5%, and the overall ditch direction is southwest to northeast.

[0048] A certain gully is a low-frequency, sparse, medium-sized debris flow gully, with a moderate susceptibility and a developed stage. The safety level standard for debris flow disaster prevention and control is Level IV, the prevention and control standard is a 20-year return period, and the debris flow rate is 98.7 m³ / h. 3 / s, the total amount of solid material in the debris flow is approximately 0.55 million m³. 3 After implementing debris flow prevention measures, the impact of debris flows on the site can be eliminated, and the site can be used for construction. Specific implementation methods are as follows:

[0049] 1. Two flexible retaining dams, one approximately 540m upstream and the other approximately 340m upstream of the earth-rock dam 2, will be constructed. The maximum heights of the two flexible retaining dams will be 5m and 8m, respectively, and their axial lengths will be 31m and 42m, respectively. The total reservoir capacity of the flexible retaining dams will be approximately 6,000 m³. 3 It meets the requirement of having a total amount of solid material that can withstand a debris flow that occurs once every 20 years.

[0050] 2. An earth-rock dam 2 is constructed downstream of the flexible retaining dam 1. The foundation elevation of the dam base is 2915.00m, the crest elevation is 2946.00m, the crest width is 5m, the upstream slope ratio is 1:2, the downstream slope ratio is 1:2, the maximum dam height is 31m, and the total length of the dam crest is approximately 69m. The dam is designed for a 20-year return period, corresponding to an upstream water level of 2940.00m. Considering the impact of excessive debris flow, the crest elevation of 2946.00m is adopted. The earth-rock dam 2 employs a seepage barrier wall 10 + composite geomembrane 8 + curtain grouting 7 for seepage prevention, ensuring the safety and stability of the earth-rock dam 2 and the construction site 12.

[0051] 3. An silt retention pond 9 is excavated upstream of the earth-rock dam 2. The lower part of the excavation is stepped, and the upper part is a gentle slope. The lower step is about 25m to 30m wide and about 100m long. The bottom of the upper gentle slope is about 20m to 25m wide and about 50m long. The silt retention pond 9 can effectively intercept solid materials passing through the flexible retaining dam 1 and ensure that the steel corrugated pipe 3 is not blocked.

[0052] 4. A corrugated steel pipe 3 is installed at the bottom of the earth-rock dam 2. The inlet of the corrugated steel pipe 3 is located upstream of the earth-rock dam 2, and the outlet is located downstream of the construction site 12. The axial length of the corrugated steel pipe 3 is about 580m, the diameter of the corrugated steel pipe 3 is 4.0m, and the maximum longitudinal slope is 9.63%. To ensure that the corrugated steel pipe 3 is not blocked, a trash rack 11 is installed at the inlet of the corrugated steel pipe. The trash rack 11 is made of 20b type I-beams, and the spacing between rows is 0.8m. To ensure the stable operation of the corrugated steel pipe 3, a pier 6 is installed at the bend of the corrugated steel pipe 3. The pier 6 is a cube with a side length of 0.8m made of concrete.

[0053] 5. An emergency corrugated steel pipe 4 is installed on the top of the earth-rock dam 2. The inlet of the emergency corrugated steel pipe 4 is located at the top of the earth-rock dam 2, and the outlet is connected to the middle of the corrugated steel pipe 3 via a tee 5. The diameter of the emergency corrugated steel pipe is 4.0m. When a debris flow exceeding the standard blocks the inlet of the corrugated steel pipe 3, the debris flow can be discharged normally through the emergency corrugated steel pipe 4. At this time, the earth-rock dam 2 plays the role of blocking the debris flow, with a storage capacity of approximately 14,000 m³. 3 It meets the requirement of blocking 12,000 cubic meters of solid material from a debris flow that occurs once every 50 years. 3 The conditions ensure the safe operation of the construction site 12.

Claims

1. A debris flow prevention system for hydropower engineering channels, characterized in that: It includes a drainage mechanism (13), and a construction site (12), an earth and rock dam (2), a silt retention pond (9) and several flexible dams (1) arranged sequentially from downstream to upstream in the ditch. The upstream end of the drainage mechanism (13) passes through the earth and rock dam (2) and connects with the silt retention pond (9). The middle part is buried in the construction site (12), and the downstream end extends to the downstream of the construction site (12). The upstream section of the bottom surface of the siltation pond (9) is excavated as a gentle slope with a longitudinal slope of no more than 10%, and the downstream section of the bottom surface of the siltation pond (9) is excavated as a stepped shape.

2. The hydropower engineering channel-type debris flow prevention system as described in claim 1, characterized in that: The platforms of each platform in the downstream section of the bottom surface of the siltation pool (9) are inclined downward relative to the downstream section in the longitudinal direction of the channel.

3. The hydropower engineering channel-type debris flow prevention system as described in claim 1, characterized in that: The earth-rock dam (2) is equipped with a seepage prevention mechanism on its water-facing surface.

4. The hydropower engineering channel-type debris flow prevention system as described in claim 3, characterized in that: The seepage prevention mechanism includes a geomembrane (8) and a concrete seepage prevention wall (10). The geomembrane (8) is located on the upper part of the water-facing side of the earth-rock dam (2), and the concrete seepage prevention wall (10) is located on the lower part of the water-facing side of the earth-rock dam (2) and is connected to the geomembrane (8). The bottom of the concrete seepage prevention wall (10) is connected to a seepage prevention curtain (7) that extends into the foundation.

5. The hydropower engineering channel-type debris flow prevention system as described in claim 1, characterized in that: The earth-rock dam (2) has a trash rack (11) at the bottom of the water-facing side. The trash rack (11) is made of multiple 20b type I-beams welded together, and the spacing between the 20b type I-beams is no more than 1m. The inlet of the discharge mechanism (13) is located inside the trash rack (11).

6. The hydropower engineering channel-type debris flow prevention system as described in claim 1, characterized in that: The drainage mechanism (13) includes a corrugated steel pipe (3), and the inlet, outlet and turning point of the corrugated steel pipe (3) are fixed by piers (6).

7. The hydropower engineering channel-type debris flow prevention system as described in claim 1, characterized in that: It also includes an emergency drainage mechanism. The upstream end of the emergency drainage mechanism passes through the earth-rock dam (2) and exits from the upper part of the water-facing side of the earth-rock dam (2) to connect with the siltation pool (9). The downstream end of the emergency drainage mechanism is connected to the middle part of the drainage mechanism (13).

8. The hydropower engineering channel-type debris flow prevention system as described in claim 7, characterized in that: The emergency drainage mechanism includes an emergency corrugated steel pipe (4), and the downstream end of the emergency corrugated steel pipe (4) is connected to the middle part of the drainage mechanism (13) through a tee (5).

9. The hydropower engineering channel-type debris flow prevention system as described in claim 8, characterized in that: The tee (5) is fixed by a retaining block (6).

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