Lower reservoir water inlet / outlet combined with rock plug and rock neck water retaining and construction method

Abstract

The application discloses a lower reservoir water inlet / outlet with rock plug and rock stem combined water retaining, and relates to the field of water inlets / outlets of lower reservoirs.

Description

Technical Field

[0001] This invention relates to a combined rock plug and rock dam water-blocking system for lower reservoir inlet / outlet and its construction method, belonging to the field of water conservancy engineering technology. Background Technology

[0002] In the design of the lower reservoir inlet / outlet of pumped storage power stations, many projects require the lower reservoir inlet / outlet to be located within an existing lower reservoir. Compared to the construction of conventional inlets, these inlets / outlets lack dry-site construction conditions and require high-risk rock plug blasting or extremely large-scale cofferdam and high rock dam construction methods to ensure the construction of the lower reservoir inlet / outlet. Therefore, whether it is possible to provide a lower reservoir inlet / outlet structure and construction method with low risk and minimal engineering workload within an existing lower reservoir has become a key issue that needs to be addressed. Summary of the Invention

[0003] The purpose of this invention is to provide a method for constructing a combined rock plug and rock dam water-blocking system for the inlet / outlet of a reservoir. This method avoids the high risks associated with rock plug blasting and minimizes the workload; it also features a simple structure that is aesthetically pleasing and economically practical.

[0004] The technical solution of this invention is as follows: A combined rock plug and rock spur for water retention in the lower reservoir, wherein the rock mass surrounding the mountain with the tailrace tunnel is divided from top to bottom into the above-water rock mass, the rock mass in the water level fluctuation zone, and the main rock spur. The main rock spur is located below the outer side of the rock mass in the water level fluctuation zone, and the bottom of the outer side of the main rock spur is a partial rock spur. The inlet / outlet of the tailrace tunnel is located at the bottom of the rock mass in the water level fluctuation zone. The end of the tailrace tunnel adjacent to the rock mass in the water level fluctuation zone is divided into a rock plug. The above-water rock mass is located above the normal water level of the existing lower reservoir. The top elevation of the rock mass in the water level fluctuation zone is basically the same as the normal water level of the existing lower reservoir, and the bottom elevation is below the dead water level. The top elevation of the main rock spur is between the normal water level and the dead water level. The top elevation of a partial rock spur is higher than the dead water level. The bottom elevations of the main rock spur and a partial rock spur are both lower than the dead water level.

[0005] A construction method for the lower reservoir inlet / outlet using a combination of rock plugs and rock culverts for water retention is disclosed. This method leverages the long construction period and large water level fluctuations inherent in pumped storage power station projects. At normal water levels, the above-water rock mass is excavated and supported. When the water level is below the top elevation of the main rock culvert, the rock mass in the water level fluctuation zone is excavated and supported. Simultaneously, the rock mass inside the tailrace tunnel is excavated through a construction adit, with a rock plug reserved for water retention. Once the water level drops below the top elevation of the main rock culvert, the accumulated water in the water level fluctuation zone is pumped out, and the rock culvert is excavated and supported within the tunnel. When the water level drops again below the top elevation of the main rock culvert, the accumulated water in the water level fluctuation zone continues to be pumped out while the main rock culvert is excavated to a partial size. Finally, a portion of the rock culvert is directionally blasted into the river channel. During the excavation of the main rock culvert, its top elevation continuously decreases, but it must always remain above the current water level.

[0006] In the aforementioned construction method for the lower reservoir inlet / outlet of a combined rock plug and rock dam water-blocking system, during the excavation of the main rock dam, safety freeboard and wave run-up requirements should be considered to ensure that it does not overtower.

[0007] The beneficial effects of the present invention are as follows: Compared with the prior art, the rock plug and rock spur combined water blocking system of the lower reservoir inlet / outlet of the present invention takes advantage of the long construction period and large water level fluctuation of pumped storage power station projects. It uses rock plugs to block water at high water levels and rock spurs to block water at low water levels, and avoids the high-risk underwater rock plug blasting. It realizes the construction of the existing lower reservoir inlet / outlet without significantly increasing the amount of engineering work.

[0008] The implementation of the above measures has reduced the construction risks of the existing reservoir inlet / outlet, while also reducing the amount of work and saving investment, resulting in significant economic benefits. Attached Figure Description

[0009] Figure 1 This is a schematic diagram of the structure of the present invention;

[0010] Figure 2 This is a schematic diagram of the construction method of the present invention. Figure 1 ;

[0011] Figure 3 This is a schematic diagram of the construction method of the present invention. Figure 2 ;

[0012] Figure 4 This is a schematic diagram of the construction method of the present invention. Figure 3 ;

[0013] Figure 5 This is a schematic diagram of the construction method of the present invention. Figure 4 .

[0014] Attached diagram labels: 1-Rock mass above water, 2-Rock mass in the water level fluctuation zone, 3-Rock mass inside the cave, 4-Rock plug, 5-Main rock sluice, 6-Partial rock sluice. Implementation

[0015] The present invention will be further described below with reference to the accompanying drawings and embodiments, but this should not be construed as limiting the present invention.

[0016] An embodiment of the present invention: a lower reservoir inlet / outlet with a combination of rock plug and rock spur for water retention, such as... Figure 1As shown, the rock mass surrounding the mountain with the tailrace tunnel, on the side adjacent to the river channel, is divided from top to bottom into: above-water rock mass 1, rock mass in the water level fluctuation zone 2, and main rock spur 5. The main rock spur 5 is located below and to the outside of the rock mass 2 in the water level fluctuation zone. The bottom of the outer side of the main rock spur 5 is part of the rock spur 6. The inlet / outlet of the tailrace tunnel is located at the bottom of the rock mass 2 in the water level fluctuation zone. The end of the tailrace tunnel adjacent to the rock mass 2 in the water level fluctuation zone is divided into a rock plug 4. The thickness of the rock plug 4 ensures no water seepage under all working conditions. The thickness of plug 4 can be calculated using a formula. The specific calculation process is a well-known technique in this field and will not be elaborated here. The bottom elevation of the rock mass 1 above the normal water level of the existing lower reservoir is above the normal water level. The top elevation of the rock mass 2 in the water level fluctuation zone is basically the same as the normal water level of the existing lower reservoir, and the bottom elevation is below the dead water level. The top elevation of the total rock spur 5 is between the normal water level and the dead water level. The top elevation of some rock spurs 6 is slightly higher than the dead water level. The bottom elevations of the total rock spur 5 and some rock spurs 6 are both lower than the dead water level.

[0017] This invention divides the rock mass of the mountainside near the river channel around the tailrace tunnel into different areas according to different water levels. During construction, different rock masses are excavated at different times, and the unexcavated rock masses are used to form a water-retaining structure. Moreover, during excavation, the excavated rock masses are all located above the water level at that time, so as to avoid the impact of water on the excavation work.

[0018] In the final stage of excavation, water is blocked by a portion of the rock ridge 6. During the excavation process, safety freeboard and wave run-up requirements should be considered to ensure that the roof does not overflow.

[0019] A construction method for the lower reservoir inlet / outlet using a combination of rock plugs and rock retaining structures to impound water utilizes the characteristics of pumped storage power station projects, such as long construction periods and large water level fluctuations. Figure 2 As shown, during normal water storage, the submerged rock mass 1 was excavated and its support completed. Since the bottom elevation of the submerged rock mass 1 is above the normal water storage level of the existing lower reservoir, the water level will not affect the excavation work of the submerged rock mass 1 when the water level is at the normal water storage level. Figure 3 As shown, when the water level is lower than the top elevation of the main rock pier 5, the rock mass 2 in the water level fluctuation zone is excavated and supported. At this time, the main rock pier 5 acts as a water barrier, and the excavation of the rock mass 2 in the water level fluctuation zone will not be affected by the water body. Simultaneously, the rock mass 3 inside the tailrace tunnel is excavated through the construction adit, with a rock plug 4 reserved to block water. Simultaneous construction of the rock mass 2 in the water level fluctuation zone and the rock mass 3 inside the tunnel can accelerate the construction progress. The reserved rock plug 4 mainly prevents seepage water that has entered the rock mass 2 area through the main rock pier 5 from flowing into the excavated tunnel and affecting the excavation of the rock mass 3 inside the tunnel. Figure 4 As shown, after the water level drops below the top elevation of the main rock spur 5, the accumulated water in the rock mass 2 of the water level fluctuation zone will be pumped out, and the rock spur 4 will be excavated using conventional construction methods, and the tunnel support will be completed. Pumping out the accumulated water in the rock mass 2 of the water level fluctuation zone will prevent the accumulated water from affecting the excavation of the rock spur 4, and will also prevent the accumulated water from flowing into the tunnel after the rock spur 4 is excavated. Figure 5 As shown, after the water level drops below the top elevation of the main rock ridge 5, the accumulated water in the rock mass 2 of the water level fluctuation zone will continue to be pumped out while the main rock ridge 5 is excavated to the size of a portion of the rock ridge 6. Since the top elevation of the portion of the rock ridge 6 is slightly higher than the dead water level, the overall volume of the portion of the rock ridge 6 is relatively small. This portion of the rock ridge 6 can be excavated by blasting. Finally, the portion of the rock ridge 6 will be directionally blasted into the river channel. During the excavation of the main rock ridge 5, the top elevation of the main rock ridge 5 will continuously decrease, but it is necessary to ensure that the top elevation of the main rock ridge 5 remains higher than the current water level. While excavating the main rock ridge 5, it is also necessary to use the main rock ridge 5 to retain water and avoid excavation operations in the water.

[0020] During the excavation of the main rock ridge 5, safety freeboard and wave run-up requirements should be considered to ensure that it does not overtower.

Claims

1. A reservoir inlet / outlet with a combination of rock plugs and rock retaining structures for water blocking, characterized in that: The rock mass surrounding the mountain with the tailrace tunnel is divided into the following sections from top to bottom: the above-water rock mass (1), the rock mass in the water level fluctuation zone (2), and the main rock stalk (5). The main rock stalk (5) is located below the outside of the rock mass in the water level fluctuation zone (2). The bottom of the outside of the main rock stalk (5) is a partial rock stalk (6). The inlet / outlet of the tailrace tunnel is located at the bottom of the rock mass in the water level fluctuation zone (2). The head of the tailrace tunnel near the rock mass in the water level fluctuation zone (2) is divided into a rock plug (4). The above-water rock mass (1) is located above the normal water level of the existing lower reservoir. The top elevation of the rock mass in the water level fluctuation zone (2) is basically the same as the normal water level of the existing lower reservoir, and the bottom elevation is below the dead water level. The top elevation of the main rock stalk (5) is between the normal water level and the dead water level. The top elevation of the partial rock stalk (6) is higher than the dead water level. The bottom elevations of the main rock stalk (5) and the partial rock stalk (6) are both lower than the dead water level.

2. A construction method for the lower reservoir inlet / outlet using a combination of rock plugs and rock retaining structures as described in claim 1, characterized in that: Taking advantage of the long construction period and large water level fluctuations of pumped storage power station projects, the above-water rock mass (1) is excavated and supported when the water level is normal. When the water level is lower than the top elevation of the total rock ridge (5), the rock mass (2) in the water level fluctuation zone is excavated and supported. At the same time, the rock mass (3) inside the tailrace tunnel is excavated through the construction adit, and a rock plug (4) is reserved to block water. After the water level drops below the top elevation of the total rock ridge (5), the water accumulated in the rock mass (2) in the water level fluctuation zone is pumped out. After the rock plug (4) is removed and the tunnel support is completed, the water level drops again to below the top elevation of the total rock spur (5). Then, the water in the rock mass (2) in the water level fluctuation zone is pumped out and the total rock spur (5) is excavated to the scale of a partial rock spur (6). Finally, the partial rock spur (6) is directionally blasted into the river channel. During the excavation of the total rock spur (5), the top elevation of the total rock spur (5) is continuously reduced, but it is necessary to ensure that the top elevation of the total rock spur (5) is always higher than the water level at that time.

3. The construction method for a combined rock plug and rock dam water-retaining system for the lower reservoir inlet / outlet according to claim 2, characterized in that: During the excavation of the main rock ridge (5), safety freeboard and wave run-up requirements should be considered to ensure that it does not overrun.

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