Inlet and outlet layout structure of the lower reservoir of a pumped-storage power station and its construction method

Abstract

The present invention relates to an inlet and outlet layout structure of a lower reservoir of a pumped-storage power station and its construction method, belonging to the technical field of the design of the lower reservoir of a pumped-storage power station. The inlet and outlet layout structure of the lower reservoir of the pumped-storage power station described in the present invention includes a natural river channel, an inlet and outlet of the lower reservoir, and a water collection groove formed by slope excavation. The water collection groove is provided with a slope support structure. The inlet and outlet of the lower reservoir are arranged in the water collection groove. One side of the water collection groove close to the natural river channel has a flow-through channel connected to the natural river channel. A plurality of underwater cast-in-place piles are fixedly arranged in the flow-through channel. The underwater cast-in-place piles enclose to form a vertical slideway. A reinforced concrete cushion layer is arranged at the bottom of the vertical slideway. A detachable and replaceable filter element is installed in the vertical slideway. One end of the bottom of the water collection groove close to the downstream of the natural river channel is connected with a sediment discharge pipeline. The sediment discharge pipeline is connected to the downstream of the natural river channel. A gate is arranged at one end of the sediment discharge pipeline close to the water collection groove.

Description

Technical Field

[0001] The present invention relates to a layout structure and a construction method for the inlet and outlet of the lower reservoir of a pumped-storage power station, belonging to the technical field of the design of the lower reservoir of a pumped-storage power station. Background Art

[0002] A pumped-storage power station generates electricity by using the height difference and circulating water. The layout pattern of the hub is mainly controlled by the upper and lower reservoirs. The combination types of the upper and lower reservoirs are rich. Among them, the upper reservoir is mostly formed by excavation or dam construction, and the lower reservoir can be formed by building a dam using a natural river course, or by using an existing reservoir or a natural river course.

[0003] Since the plant units of a pumped-storage power station need to circulate water for pumping and generating electricity, the requirement for water quality is very high, especially the sediment content, which is related to the service life of the plant units; and excessive sediment deposition will also lead to a reduction in the reservoir capacity and a decrease in the power generation efficiency. Generally, northern rivers have a lot of sediment. Many pumped-storage power stations are severely restricted in development due to the excessive sediment content in the water body and the high treatment cost.

[0004] The conventional method for dealing with excessive sediment content is to set two dam bodies in the lower reservoir river course and divert the river (generally, it can be realized by using a diversion tunnel or a diversion open channel). The water in the river no longer flows into the lower reservoir, so as to reduce the sediment content. For reference, see Figure 1 However, the cost of the two dam bodies and the river diversion is high, the construction period is long, the cost is large, and it requires a river bend in the site planning, which is severely restricted by the terrain; or excavate a lower reservoir in a suitable terrain above the river. For reference, see Figure 2 That is, both the upper reservoir and the lower reservoir are artificially built, without using natural river courses or reservoirs, and are formed by excavation. Restricted by the terrain, most sites are difficult to realize, and the river course is the lowest groundwater drainage reference surface, and the anti-seepage problem is particularly prominent.

[0005] In addition, the patent document with the publication number CN214363795U discloses a sand-concentrating structure for a multi-sediment river, including: a water-collecting corridor, a non-sand concrete pipe, concrete, pebbles, gravel, coarse sand and medium sand; a plurality of non-sand concrete pipes that are connected to and perpendicular to the water-collecting corridor are arranged on both sides of the water-collecting corridor, and a layer of concrete is backfilled and laid at the bottom of each non-sand concrete pipe; a layer of pebbles is laid outside the water-collecting corridor and the non-sand concrete pipes; a layer of gravel is laid on the pebbles; a layer of coarse sand is laid on the gravel; and a layer of medium sand is laid on the coarse sand. Although this solution can effectively solve the problems of difficult water intake and sand removal in a multi-sediment river, control the sediment content of the water entering the reservoir, and ensure the effective reservoir capacity of the energy storage reservoir, the filter layer of the sand-concentrating structure in the above solution is horizontally laid and then vertically stacked, resulting in sediment deposition above the filter of the sand-concentrating structure, reducing the water intake efficiency of the sand-concentrating structure, and the maintenance is extremely inconvenient. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide an inlet and outlet layout structure for the lower reservoir of a pumped - storage power station, which can be applicable to the working conditions of multi - sediment rivers, and at the same time has the advantages of simple structure, low implementation cost, high water intake efficiency and convenient maintenance.

[0007] The technical solution adopted by the present invention to solve the above - mentioned technical problem is: an inlet and outlet layout structure for the lower reservoir of a pumped - storage power station, including a natural river, an inlet and outlet of the lower reservoir, and a water - collecting groove formed by slope excavation. The water - collecting groove is provided with a slope support structure. The inlet and outlet of the lower reservoir is arranged in the water - collecting groove. One side of the water - collecting groove close to the natural river has a flow - through channel connected to the natural river. A plurality of underwater cast - in - place piles are fixedly arranged in the flow - through channel. The axes of the underwater cast - in - place piles are all vertically arranged. A prestressed stirrup is integrally sleeved on the outer periphery of the plurality of underwater cast - in - place piles. The underwater cast - in - place piles enclose a vertical slideway. A reinforced concrete cushion is arranged at the bottom of the vertical slideway. A detachable and replaceable filter element is installed in the vertical slideway. The filter element includes a first gravel layer, a first coarse sand layer, a medium sand layer, a second coarse sand layer and a second gravel layer which are sequentially stacked in the horizontal direction. The first gravel layer faces the water - collecting groove, and the second gravel layer faces the natural river. The outsides of the first gravel layer, the first coarse sand layer, the medium sand layer, the second coarse sand layer and the second gravel layer are all wrapped and shaped by a fine - mesh net. The fine - mesh net uses a first steel cage as a support framework. One end of the bottom of the water - collecting groove close to the downstream of the natural river is connected with a sand - discharging pipeline. The sand - discharging pipeline is connected to the downstream of the natural river. A gate for controlling the opening and closing of the internal flow channel is arranged at one end of the sand - discharging pipeline close to the water - collecting groove.

[0008] A further preferred solution is that the first steel cages corresponding to the first gravel layer, the first coarse sand layer, the medium sand layer, the second coarse sand layer and the second gravel layer are all fixedly placed in the second steel cage.

[0009] A further preferred solution is that the underwater cast - in - place piles are arranged in two rows, and a plurality of piles are evenly spaced in each row. A vertical slideway corresponding to a filter element is formed by four underwater cast - in - place piles arranged in a rectangle. A plurality of filter elements are continuously arranged along the length direction of the natural river.

[0010] A further preferred solution is that concrete end columns are arranged at the outer ends of the two filter elements at the ends. The side of the concrete end column facing the filter element is fixedly connected to the underwater cast - in - place pile to form an integral body, and a chute adapted to the end of the filter element is combined. A pipeline for the prestressed stirrup to pass through is embedded in the concrete end column.

[0011] A further preferred solution is that a gap closing device is arranged in the assembly gap between two adjacent filter elements; the gap closing device includes two closing plates arranged oppositely, a sponge layer is provided on the side of the closing plate facing the filter element, a plurality of bolt holes are arranged between the two closing plates, a screw rod is inserted into the bolt holes, a nut is arranged on the screw rod, and the nut is arranged on the side of the closing plate away from the filter element. By tightening the nut, the sponge layer on the closing plate is in close contact with the filter element; the space between the two closing plates is filled with medium-coarse sand by vibration compaction.

[0012] A further preferred solution is that the slope support structure includes a plurality of grouting anchor rods anchored in the rock mass.

[0013] A further preferred solution is that the axis of the grouting anchor rod is arranged perpendicular to the slope surface.

[0014] Based on the layout structure of the inlet and outlet of the lower reservoir of the pumped-storage power station described above, the present invention correspondingly provides a construction method for the layout structure of the inlet and outlet of the lower reservoir of the pumped-storage power station, including the following steps:

[0015] A. Drive steel sheet pile cofferdams to isolate the construction area from the natural river channel and form a construction foundation pit.

[0016] B. Construct underwater cast-in-place piles with a rotary drilling rig.

[0017] C. Excavate the water collection groove in layers, and timely support the rock slope after each layer of excavation.

[0018] D. Construct the inlet and outlet of the lower reservoir.

[0019] E. Construct the sand discharge pipeline by the pipe jacking method and install the gate of the sand discharge pipeline.

[0020] F. Excavate to form a flow-through channel for installing the filter element and construct a reinforced concrete cushion; if there are concrete end columns arranged, construct the concrete end columns at the same time.

[0021] G. Pre-fabricate the filter element in advance, lift the filter element to the corresponding installation area with a crane and install the filter element.

[0022] H. Construct prestressed stirrups.

[0023] I. Pull out the steel sheet piles and remove the cofferdam.

[0024] The beneficial effects of the present invention are as follows: The present invention directly utilizes a natural river channel as the lower reservoir. The water inlet and outlet of the lower reservoir of the pumped-storage power station are separately arranged from the lower reservoir. The water inlet and outlet of the lower reservoir are arranged in a water collection groove formed by slope excavation. The filter element can effectively filter out the sediment in the river, making the water in the water collection groove meet the sediment content requirements of the pumped-storage power station. The effective storage capacity of the lower reservoir in the present invention mainly relies on the natural river channel, and the excavation workload of the water collection groove is small, and the construction cost is low. In addition, each filter layer of the filter element is arranged in the "vertical direction". During the pumping and power generation process of the pumped-storage power station, the filter element can be circularly cleaned, prolonging the service life of the filter element; the filter element is designed to be detachable and replaceable, and can be replaced by using a hoisting device for hoisting, ensuring the water replenishment efficiency of the pumped-storage power station. When the structure has been in long-term operation and there is a large amount of sand accumulation in the water collection groove, when draining water at the water inlet and outlet of the lower reservoir, the gate on the sediment discharge pipeline can be opened. Under the principle of "constricting water to flush sediment", the sediment in the water collection groove flows into the inlet of the sediment discharge pipeline and flows out from the outlet of the sediment discharge pipeline, and finally flows into the downstream river channel. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a schematic plan structure diagram when implementing the prior art one.

[0026] Figure 2 is a schematic elevation structure diagram when implementing the prior art two.

[0027] Figure 3 is a schematic elevation structure diagram when implementing the present invention.

[0028] Figure 4 is a schematic plan structure diagram when implementing the present invention.

[0029] Figure 5 is Figure 4 a partial enlarged schematic diagram of the flow-through channel and the area where the filter element is located in

[0030] Figure 6 is a schematic diagram of the decomposed structure of the filter element in the present invention.

[0031] Figure 7 is a schematic diagram of the structure of the gap sealing device in the present invention.

[0032] Reference numerals in the drawings: natural river channel 1, water collection groove 2, flow-through channel 3, underwater cast-in-place pile 4, filter element 5, first gravel layer 51, first coarse sand layer 52, medium sand layer 53, second coarse sand layer 54, second gravel layer 55, water inlet and outlet of the lower reservoir 6, sediment discharge pipeline 7, gate 8, prestressed stirrup 9, concrete end column 10, closing plate 11, screw 12, grouting anchor 13, lower reservoir area 20, dam body 30, river diversion structure 40, upper reservoir area 50. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0033] The present invention will be further described below in conjunction with the accompanying drawings.

[0034] As Figures 3 to 7 shown, the inlet and outlet arrangement structure of the lower reservoir of the pumped-storage power station described in the present invention includes a natural river channel 1, an inlet and outlet 6 of the lower reservoir, and a water collection groove 2 formed by slope excavation. The water collection groove 2 is provided with a slope support structure. The inlet and outlet 6 of the lower reservoir is arranged in the water collection groove 2. One side of the water collection groove 2 close to the natural river channel 1 has a flow-through channel 3 connected to the natural river channel 1. A plurality of underwater cast-in-place piles 4 are fixedly arranged in the flow-through channel 3. The axes of the underwater cast-in-place piles 4 are all vertically arranged. A prestressed stirrup 9 is integrally sleeved on the outer periphery of the plurality of underwater cast-in-place piles 4. The underwater cast-in-place piles 4 enclose a vertical slideway. A reinforced concrete cushion is arranged at the bottom of the vertical slideway. A detachable and replaceable filter element 5 is installed in the vertical slideway. The filter element 5 includes a first gravel layer 51, a first coarse sand layer 52, a medium sand layer 53, a second coarse sand layer 54, and a second gravel layer 55 sequentially stacked in the horizontal direction. The first gravel layer 51 faces the water collection groove 2, and the second gravel layer 55 faces the natural river channel 1. That is, each filtering structure layer of the filter element 5 is vertically arranged. The outsides of the first gravel layer 51, the first coarse sand layer 52, the medium sand layer 53, the second coarse sand layer 54, and the second gravel layer 55 are all wrapped and shaped by a dense mesh. The dense mesh uses a first steel cage as a support skeleton. The bottom of the water collection groove 2 is connected with a sediment discharge pipe 7 at one end close to the downstream of the natural river channel 1. The sediment discharge pipe 7 is connected to the downstream of the natural river channel 1. A gate 8 for controlling the opening and closing of the internal flow passage is arranged at one end of the sediment discharge pipe 7 close to the water collection groove 2.

[0035] When the structure construction is completed, during the operation of the hydropower station, when the inlet and outlet 6 of the lower reservoir pumps water to the upper reservoir, the water level in the water collection groove 2 drops. According to the principle of communicating vessels, the water in the natural river channel 1 replenishes the water collection groove 2 and is filtered by the filter element 5, and the sediment content is reduced. When the inlet and outlet 6 of the lower reservoir discharges water for power generation, the water level in the water collection groove 2 rises, higher than the water level of the natural river channel 1, and the water discharges into the natural river channel 1. When passing through the filter element 5, the residual medium and fine sand in the gaps of the filter element 5 can be washed, and the service life of the filter element 5 can be extended. When the structure operates for a long time and the filter element 5 is blocked, and the water replenishment and drainage are not smooth, the filter element 5 can be disassembled and replaced by a crane. When the structure operates for a long time and there is a large amount of sand accumulation in the water collection groove 2, when the inlet and outlet 6 of the lower reservoir discharges water, the gate on the sediment discharge pipe 7 can be opened. Under the principle of "constricting water to flush sand", the sediment in the water collection groove 2 flows into the inlet of the sediment discharge pipe 7 and flows out from the outlet of the sediment discharge pipe 7, and finally flows into the downstream river channel.

[0036] It is understandable that, in order to facilitate installation and disassembly and replacement, the filter element 5 should be fixed as a whole, and the first steel cages corresponding to each structural layer can be fixed as a whole by welding, bolting, etc. In order to make the structure more reliable and easy to assemble, it is preferred that the first steel cages corresponding to the first crushed stone layer 51, the first coarse sand layer 52, the medium sand layer 53, the second coarse sand layer 54 and the second crushed stone layer 55 are all fixedly placed in the second steel cage. With a double-layer steel cage structure, a single filter element can have stronger rigidity.

[0037] The main function of the underwater cast-in-place pile 4 and the prestressed stirrups 9 is to prevent the filter element 5 from sliding into the water collection groove 2 or the natural river channel 1 and damaging the filtering device. The prestressed stirrups 9 are arranged around the underwater cast-in-place pile 4 to enhance the integrity of the underwater cast-in-place pile 4 and also prevent the underwater cast-in-place pile 4 from failing. The underwater cast-in-place pile 4 also has the function of fixing the foot of the slope to prevent the rock and soil at the foot of the slope from being squeezed and damaged, thereby causing the slope to slide.

[0038] The preferred arrangement of the underwater cast-in-place piles 4 is as follows: the underwater cast-in-place piles 4 are arranged in two rows, with multiple piles arranged evenly spaced in each row, and four underwater cast-in-place piles 4 arranged in a rectangular shape form a vertical slideway corresponding to a filter element 5, and multiple filter elements 5 are arranged continuously along the length direction of the natural river channel 1.

[0039] Since a sand discharge pipe 7 and a gate 8 are designed, even if a small amount of silt enters the water collection groove 2, it will not affect the normal operation of the overall structure. However, in order to avoid silt from entering the water collection groove 2 as much as possible and reduce the frequency of opening the gate 8, the present invention can adopt the following preferred scheme. The two filter elements 5 located at the end are equipped with a concrete end column 10 at the outer end of the filter element 5. The side of the concrete end column 10 facing the filter element 5 is fixedly connected to the underwater cast-in-place pile 4 as a whole, and combined into a slideway compatible with the end of the filter element 5; a pipe for the prestressed stirrups 9 to pass through is pre-buried in the concrete end column 10. This scheme is particularly suitable for situations where the shape of the upstream and downstream rock foundation surfaces is irregular. In this scheme, the filter element 5 is not directly connected to the upstream and downstream rock masses. The steel bars are tied to the upstream and downstream rock foundation surfaces, and concrete is poured. The inner side of the concrete is formed with the help of a template, and the concrete end column 10 is formed after the concrete hardens.

[0040] For the convenience of construction and assembly, there is a necessary assembly gap between two adjacent filter elements 5. The preferred solution is that a gap closing device is provided in the assembly gap between two adjacent filter elements 5; the gap closing device includes two closing plates 11 arranged oppositely. The closing plates are preferably galvanized iron plates. One side of the closing plate 11 facing the filter element 5 has a sponge layer. A plurality of bolt holes are provided between the two closing plates 11, and a screw rod 12 is inserted through the bolt holes. A nut is provided on the screw rod 12, and the nut is arranged on the side of the closing plate 11 away from the filter element 5. By tightening the nut, the sponge layer on the closing plate 11 is in close contact with the filter element 5 (that is, the sponge layer has a set range of compression in the thickness direction); the space between the two closing plates 11 is filled with medium coarse sand by vibration compaction.

[0041] When forming the water collecting groove 2 by slope excavation, it is necessary to carry out support while excavating in layers. The specific support structure can be flexibly arranged according to the terrain conditions, and generally includes at least a plurality of grouting anchor rods 13 anchored in the rock mass. The grouting anchor rods 13 can lock the rock slope to prevent the unloading cracks of the rock mass from continuously developing due to the operation disturbance of the inlet and outlet 6 of the lower reservoir and the influence of weathering, thereby causing the slope to collapse.

[0042] The layout structure of the inlet and outlet of the lower reservoir of the above-mentioned pumped-storage power station specifically includes the following steps during construction:

[0043] A. Drive steel sheet pile cofferdams to isolate the construction area from the natural river 1 to form a construction foundation pit; during specific implementation, it should be ensured that there is no water or little water in the foundation pit during construction;

[0044] B. Use a rotary drilling rig to construct underwater cast-in-place piles 4; the underwater cast-in-place piles 4 on the riverside can cooperate with the steel sheet piles to reinforce the cofferdam to ensure the safety of internal construction in the foundation pit;

[0045] C. Excavate the water collecting groove 2 in layers. For each layer excavated, timely carry out the support of the rock slope, that is, construct the grouting anchor rods 13;

[0046] D. Construct the inlet and outlet 6 of the lower reservoir;

[0047] E. Use the pipe jacking method to construct the sediment discharge pipeline 7 and install the gate 8 of the sediment discharge pipeline 7;

[0048] F. Excavate to form the flow-through channel 3 for installing the filter element 5 and construct the reinforced concrete cushion; if there are concrete end columns 10 arranged, construct the concrete end columns 10 at the same time;

[0049] G. Pre-fabricate the filter element 5 in advance and use a crane to hoist the filter element 5 to the corresponding installation area and install the filter element 5;

[0050] H. Construct the prestressed stirrups 9;

[0051] I. Pull out the steel sheet piles and remove the cofferdam.

Claims

1. Layout structure of the intake and outlet of the lower reservoir of a pumped-storage power station, comprising a natural river channel (1) and the intake and outlet of the lower reservoir (6), characterized in that: It includes a water collection groove (2) formed by slope excavation. The water collection groove (2) is equipped with a slope support structure. The inlet / outlet (6) of the lower reservoir is arranged in the water collection groove (2). One side of the water collection groove (2) close to the natural river channel (1) has a flow-through channel (3) connected to the natural river channel (1). A plurality of underwater cast-in-place piles (4) are fixedly arranged in the flow-through channel (3). The axes of the underwater cast-in-place piles (4) are all vertically arranged. A prestressed stirrup (9) is integrally sleeved on the outer periphery of the plurality of underwater cast-in-place piles (4). The underwater cast-in-place piles (4) enclose a vertical slideway. A reinforced concrete cushion is arranged at the bottom of the vertical slideway. A detachable and replaceable filter element (5) is installed in the vertical slideway. The filter element (5) includes a first gravel layer (51), a first coarse sand layer (52), a medium sand layer (53), a second coarse sand layer (54), and a second gravel layer (55) stacked in sequence along the horizontal direction. The first gravel layer (51) faces the water collection groove (2), and the second gravel layer (55) faces the natural river channel (1). The outsides of the first gravel layer (51), the first coarse sand layer (52), the medium sand layer (53), the second coarse sand layer (54), and the second gravel layer (55) are all shaped by being wrapped with a dense mesh. The dense mesh uses a first steel reinforcement cage as a support skeleton. At one end of the bottom of the water collection groove (2) close to the downstream of the natural river channel (1), a sand discharge pipeline (7) is connected. The sand discharge pipeline (7) is connected to the downstream of the natural river channel (1). A gate (8) for controlling the opening and closing of the internal flow channel is arranged at one end of the sand discharge pipeline (7) close to the water collection groove (2). The underwater cast-in-place piles (4) are arranged in two rows, and multiple piles are evenly spaced in each row. Four underwater cast-in-place piles (4) arranged in a rectangle form a vertical slideway corresponding to a filter element (5). A plurality of filter elements (5) are continuously arranged along the length direction of the natural river channel (1). At the two filter elements (5) located at the ends, concrete end columns (10) are arranged at the outer ends of the filter elements (5). One side of the concrete end column (10) facing the filter element (5) is fixedly connected to the underwater cast-in-place pile (4) to form an integral body and combined into a chute adapted to the end of the filter element (5). A pipeline for the prestressed stirrup (9) to pass through is embedded in the concrete end column (10). A gap closing device is arranged in the assembly gap between two adjacent filter elements (5). The gap closing device includes two closing plates (11) arranged oppositely. One side of the closing plate (11) facing the filter element (5) has a sponge layer. A plurality of bolt holes are arranged between the two closing plates (11), and a screw rod (12) is inserted into the bolt holes. A nut is arranged on the screw rod (12), and the nut is arranged on the side of the closing plate (11) away from the filter element (5). By tightening the nut, the sponge layer on the closing plate (11) is in close contact with the filter element (5). The spaced space between the two closing plates (11) is filled with medium coarse sand by vibration.

2. The inlet and outlet layout structure of the lower reservoir of the pumped-storage power station according to claim 1, wherein: The first steel reinforcement cages corresponding to the first gravel layer (51), the first coarse sand layer (52), the medium sand layer (53), the second coarse sand layer (54), and the second gravel layer (55) are all fixedly placed in the second steel reinforcement cage.

3. The water inlet and outlet layout structure of the lower reservoir of the pumped-storage power station according to claim 1, characterized in that: The slope support structure includes multiple grouting anchor rods (13) anchored in the rock mass.

4. Construction method for layout structure of intake and outlet of lower reservoir of pumped storage power station, characterized in that, Adopt the layout structure of the intake and outlet of the lower reservoir of the pumped-storage power station as described in any one of claims 1 to 3, and include the following steps: A. Construct a steel sheet pile cofferdam to isolate the construction area from the natural river (1) to form a construction foundation pit; B. Use a rotary drilling rig to construct an underwater cast-in-place pile (4); C. Excavate the water collection groove (2) in layers. For each layer excavated, promptly carry out the support of the rock slope; D. Construct the intake and outlet (6) of the lower reservoir; E. Use the pipe jacking method to construct the sediment discharge pipeline (7) and install the gate (8) of the sediment discharge pipeline (7); F. Excavate to form a flow-through channel (3) for installing the filter element (5), and construct a reinforced concrete cushion; if there are concrete end columns (10) arranged, construct the concrete end columns (10) simultaneously; G. Pre-fabricate the filter element (5) in advance, and use a crane to hoist the filter element (5) to the corresponding installation area and install the filter element (5); H. Construct the prestressed stirrups (9); I. Pull out the steel sheet piles and remove the cofferdam.

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