Graded desilting and desilting system and method suitable for side type water inlet / outlet of canyon type riverbed

Abstract

The invention provides a graded desilting and desilting system and method suitable for a side type water inlet / outlet of a canyon type riverbed. The graded desilting and desilting system comprises a first-stage desilting structure and a second-stage desilting facility. The first-stage desilting structure is arranged at the position of a lower reservoir river section between a lower reservoir barrage and a lower reservoir sediment storage dam, one side of the section is a water inlet / outlet rear side slope, and the other side of the section is an opposite side slope. And the second-stage desilting facility is used for treating silt deposited in the forebay and the reverse slope section due to the over-standard flood. According to the direction from the rear side slope to the opposite side slope, the side type water inlet / outlet, the forebay, the reverse slope section, the sand blocking ridge and the sand discharging channel are sequentially included. The first-stage desilting structure is used for dredging frequent flood silt; through the grading treatment mode that structural sand blocking and guiding are dominated and mechanical desilting is assisted, the problem of sediment deposition of the front edge and the reverse slope section of the side type water inlet / outlet of the canyon type riverbed is effectively solved, and the safety and reliability of long-term operation of the canyon type riverbed are guaranteed.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of water conservancy and hydropower engineering facilities, and particularly relates to a hierarchical desilting and sand discharge system and method suitable for a side-type inlet / outlet of a gorge-type riverbed. BACKGROUND

[0002] The inlet / outlet is an important node facility of the water delivery system of a pumped storage power station, and plays a key role in regulating the flow state of inlet and outlet water, ensuring smooth transition of water flow and efficient conversion of energy. The structure mainly has two typical structural forms of side type and well type, and is generally arranged at the head of the water delivery system and the front end of the tailwater system, which has important engineering value for ensuring the overall operation efficiency of the water delivery line.

[0003] The side-type inlet / outlet has the advantages of convenient construction, small water head loss and stable water flow conditions due to its close arrangement to the reservoir bank. However, since the side-type inlet / outlet directly connects with the natural riverbed, it is more easily affected by the riverbed sediment transport under narrow hydraulic conditions such as gorge-type riverbeds, resulting in continuous sediment accumulation in front of the inlet, which seriously affects the flow capacity and operation safety. In traditional engineering, a front anti-slope type sand dam structure is often used to achieve initial interception of coarse particle sediment by setting a height difference. Although this design is effective in a certain period, it has obvious limitations in long-term operation: first, sediment continuously accumulates in front of the dam, forming a permanent sediment body, and the effective sand discharge volume decreases year by year; second, fine particle suspended sediment is easily penetrated by flow around the structure under the action of water flow turbulence, affecting the durability of the structure.

[0004] In view of the above problems, the existing design ideas often face a dilemma: if only the standard flood is prevented, the super-standard flood will cause serious sediment accumulation risk after entering the reservoir; and if the design standard is improved comprehensively, the project scale will be expanded and the investment will increase, causing economic waste. Therefore, it is of great significance to effectively solve the above problems. SUMMARY

[0005] In view of the defects of the prior art, the application provides a hierarchical desilting and sand discharge system and method suitable for a side-type inlet / outlet of a gorge-type riverbed, which can effectively solve the above problems.

[0006] The technical scheme adopted by the application is as follows:

[0007] The application provides a hierarchical desilting and sand discharge system suitable for a side-type inlet / outlet of a gorge-type riverbed, which comprises a primary sand discharge structure.

[0008] The primary sand discharge structure is arranged at the lower reservoir river section between the lower reservoir dam and the lower reservoir sand dam, one side of the section is the back slope behind the water inlet / outlet, and the other side is the opposite bank slope (6), and in the direction from the back slope to the opposite bank slope (6), it includes the side-type water inlet / outlet (1), the front pool (2), the reverse slope section (3), the sand dam (4) and the sand discharge channel (5) in sequence.

[0009] The side-type water inlet / outlet (1) is provided with the front pool (2) away from the back slope, the bottom elevation of the front pool (2) is lower than that of the side-type water inlet / outlet (1), forming a sand setting area; the left side slope bottom of the reverse slope section (3) is overlapped with the right side bottom of the front pool (2); the reverse slope section (3) is an upward inclined slope surface from left to right at the lower reservoir river section, the right side slope top of the reverse slope section (3) is close to the opposite bank slope (6) and close to the lower reservoir water surface line; the sand dam (4) is arranged on the right side slope top edge of the reverse slope section (3) along the longitudinal direction of the river; the sand discharge channel (5) is formed between the sand dam (4) and the opposite bank slope (6), and the sand discharge channel (5) is arranged along the longitudinal direction of the river, and the front and back ends thereof are communicated with the lower reservoir sand dam and the lower reservoir dam respectively; the elevation of the sand discharge channel (5) is flush with the lower reservoir bottom downstream of the lower reservoir sand dam and the upper reservoir bottom upstream of the lower reservoir dam.

[0010] Further, the side-type water inlet / outlet (1) is arranged in the natural deep and narrow river landscape formed by the extrusion of the two bank mountains.

[0011] Further, the side-type water inlet / outlet (1) is constructed by reinforced concrete, and in the direction of the water flow from the opposite bank slope (6) to the back slope, it includes the vortex-proof beam section (101), the adjustment section (102), the diffusion section (103) and the gate well section (104) in sequence.

[0012] The vortex-proof beam section (101) and the adjustment section (102) are equal-section water conveying pipelines along the water flow direction; the diffusion section (103) is a variable-section water conveying pipeline with gradually reduced cross section along the water flow direction, and the cross section size thereof is the same as that of the connection section between the adjustment section (102) and the diffusion section (103); the gate well section (104) is an equal-section water conveying pipeline along the water flow direction, and the cross section size thereof is the same as that of the connection section between the diffusion section (103) and the gate well section (104).

[0013] Further, two side-type water inlets / outlets (1) are arranged side by side, and the right ends of the two side-type water inlets / outlets (1) are communicated with the front pool (2); the left ends of the two side-type water inlets / outlets (1) are connected by a gate well platform (12) to form a whole;

[0014] The interval area is provided between the two side-type water inlet / outlet ports (1); a center line of the interval area is provided with, in sequence from the front pool (2) to the gate shaft platform (12), a trash rack maintenance platform (9), a trash rack connecting bridge (10) and a slope below the gate shaft platform (11).

[0015] Further, the front pool (2) is a rectangular reinforced concrete structure, and the thickness of the bottom plate is 250 mm; the height difference between the bottom elevation of the front pool (2) and the bottom plate elevation of the side-type water inlet / outlet port (1) is 1.5-2.5 m.

[0016] Further, the excavation slope ratio of the reverse slope section (3) is 1:4, and the excavation slope ratio of the two sides is 1:1.2; the sand trap (4) is a prismatic reinforced concrete structure, the top width is 1 m, and the height is 2.5-3 m; the width of the sand discharge channel (5) is 10 m, and a layer of cement mortar (7) with a thickness of not less than 5 cm is laid as a leveling layer at the bottom.

[0017] Further, the secondary dredging facilities are further included; the secondary dredging facilities include a dredging device, a long-distance sand discharge pipeline (14) and a short-distance sand discharge pipeline (15);

[0018] The dredging device adopts a cutter suction dredger, which is used for twisting the accumulated silt in the front pool (2) and the reverse slope section (3) to form slurry;

[0019] The laying path of the short-distance sand discharge pipeline (15) is that: on the slope surface of the reverse slope section (3), the laying path is serpentine from the top of the slope to the bottom of the slope; then to the front pool (2), after passing through the bottom of the front pool (2), to the trash rack maintenance platform (9), and then to the straight-line laying on the slope surface of the slope below the gate shaft platform (11), and finally to the gate shaft platform (12);

[0020] The laying path of the long-distance sand discharge pipeline (14) is that: the laying path is straight-line on the bottom of the front pool (2), to the bottom of the reverse slope section (3), then serpentine on the slope surface of the reverse slope section (3) from the bottom of the slope to the top of the slope, then from the top of the reverse slope section (3) through the left abutment of the sand trap of the lower reservoir, along the reservoir surface of the sand trap of the lower reservoir, and finally to the top of the sand trap of the lower reservoir.

[0021] The application further provides a dredging and sand discharge method suitable for the graded dredging and sand discharge system of the side-type water inlet / outlet port of the gorge type riverbed;

[0022] Step S1, the primary sand discharge method:

[0023] Step S101, when the lower reservoir is in pumping state, the water stored in the lower reservoir dam and the lower reservoir sand dam is collected under the action of topography and flows into the sand discharge channel (5). Under the interception of the sand dam (4), the main sediment in the water body is blocked in the sand discharge channel (5);

[0024] Step S102, the water body containing a small amount of sediment flows into the reverse slope section (3) after passing through the sand dam (4); after the deceleration and energy dissipation of the reverse slope section (3), a small amount of sediment is deposited on the slope surface of the reverse slope section (3);

[0025] Step S103, after the action of the reverse slope section (3), the water body containing a small amount of sediment flows into the front pool (2), and the front pool (2) removes a small amount of sediment in the water body;

[0026] The water body after removing sediment flows into the side type inlet / outlet (1), and under the action of the water turbine, it is transported to the upper reservoir, completing the pumping condition;

[0027] Step S104, when the lower reservoir is replenished, the water in the lower reservoir sand dam flows into the lower reservoir through the lower reservoir sand dam. During the flow of the water, the deposited sediment in the sand discharge channel (5) is scoured, and the deposited sediment is guided to the bottom of the lower reservoir dam to ensure that there is no sediment in front of the sand dam (4) during the pumping condition;

[0028] Step S2, secondary dredging method:

[0029] Step S201, when the sediment accumulation thickness in the front pool (2) and the reverse slope section (3) exceeds the design standard of the primary sediment discharge structure, the dredging device is started to twist the accumulated sediment in the front pool (2) and the reverse slope section (3), forming slurry;

[0030] Step S202, under the action of the pump, the slurry is discharged to the designed location through the long-distance sand discharge pipeline (14) and / or the short-distance sand discharge pipeline (15).

[0031] Further, the short-distance sand discharge pipeline (15) discharges in the following way: the slurry in the reverse slope section (3) and the front pool (2) area is discharged to the gate well platform (12) through the sand discharge pipeline, and is transported out by vehicles at the position of the gate well platform (12);

[0032] The long-distance sand discharge pipeline (14) discharges in the following way: the slurry in the front pool (2) and the slurry in the reverse slope section (3) area is discharged into the top of the lower reservoir sand dam through the sand discharge pipeline, and is transported out by vehicles at the position of the top of the lower reservoir sand dam.

[0033] Further, the sediment starting flow velocity in front of the sand dam (4) And the sediment starting particle size Have the relationship formula (1):

[0034] (1)

[0035] wherein: , are water and sediment density respectively; is the sediment incipient particle size; is the gravity acceleration; is the water depth in the sediment discharge channel (5);

[0036] The flow velocity of the front section of the sediment barrier (4) is taken as the sediment incipient flow velocity in the sediment discharge channel (5) , and the sediment incipient particle size is calculated based on the relationship (1); therefore, when the actual reservoir bottom sediment particle size is greater than the sediment incipient particle size , it indicates that the sediment will not cross the sediment barrier (4) to enter the reverse slope section (3) and the front pool (2), and the sediment barrier (4) is reasonably set; therefore, the sediment barrier (4) at the outer edge of the side-type inlet / outlet (1) is designed so that the flow velocity of the front section thereof is lower than the sediment incipient flow velocity of the reservoir bottom, so that the effective sediment discharge effect of the sediment discharge channel (5) can be achieved.

[0037] The side-type inlet / outlet graded sediment dredging and discharging system and method suitable for a gorge-type riverbed provided by the present application has the following advantages:

[0038] The present application effectively solves the sediment accumulation problem of the front edge and the reverse slope section of the side-type inlet / outlet of the gorge-type riverbed through the graded management mode of "mainly guiding sediment by structure and supplementarily dredging sediment by machinery", and ensures the safety and reliability of long-term operation. BRIEF DESCRIPTION OF DRAWINGS

[0039] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description only show some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative labor.

[0040] Fig. 1 is a plane schematic view of a side-type inlet / outlet graded sediment dredging and discharging system suitable for a gorge-type riverbed;

[0041] Fig. 2 is a local enlarged view of a sediment discharge channel section of the side-type inlet / outlet graded sediment dredging and discharging system suitable for a gorge-type riverbed;

[0042] Fig. 3 is a schematic view of a long-distance sediment dredging and discharging method suitable for a side-type inlet / outlet of a gorge-type riverbed;

[0043] Fig. 4 is a short-distance dredging and desilting method suitable for the side-type inlet / outlet of a canyon-type riverbed;

[0044] Wherein: 1---side-type inlet / outlet; 2---front pool; 3---reverse slope section; 4---sand blocking ridge; 5---desilting passage; 6---opposite bank slope; 7---cement mortar; 8---excavation boundary line; 9---trash rack maintenance platform; 10---trash rack connecting bridge; 11---slope below gate well platform; 12---gate well platform; 13---riverbed surrounding rock; 14---long-distance desilting pipeline; 15---short-distance desilting pipeline; 16---water level line; 101---anti-vortex beam section; 102---adjustment section; 103---diffusion section; 104---gate well section;

[0045] The arrow direction is the dredging direction. DETAILED DESCRIPTION

[0046] In order to make the technical problems, technical solutions and beneficial effects of the present application clearer, the present application will be further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application and do not limit the present application.

[0047] The present application provides a staged dredging and desilting system and method suitable for the side-type inlet / outlet of a canyon-type riverbed, which is a staged dredging and desilting system suitable for the characteristics of a canyon-type riverbed. The system combines desilting facilities and super-standard accumulation cleaning measures to balance the engineering economy and operation reliability.

[0048] Specifically, the present application is a staged dredging and desilting system and method suitable for the side-type inlet / outlet of a canyon-type riverbed. Based on the optimization of sand blocking structures, the staged management concept is introduced to build a sediment control system mainly relying on structural sand blocking and assisted by mechanical dredging, forming an efficient and economical dredging and desilting scheme in the whole life cycle, which provides reliable protection for the long-term safe and stable operation of pumped storage power stations.

[0049] The present application provides a staged dredging and desilting system suitable for the side-type inlet / outlet of a canyon-type riverbed, which comprises a primary desilting structure. The primary desilting structure realizes the staged desilting of the side-type inlet / outlet through the cooperation of various components with different elevations and spatial structures.

[0050] Referring to Figs. 1 to 4 , the primary desilting structure is arranged at the lower reservoir river channel section position between the lower reservoir dam and the lower reservoir sand blocking dam. One side of the section is the rear slope of the inlet / outlet, and the other side is the opposite bank slope 6. In the direction from the rear slope to the opposite bank slope 6, the primary desilting structure comprises, in sequence, the side-type inlet / outlet 1, the front pool 2, the reverse slope section 3, the sand blocking ridge 4 and the desilting passage 5.

[0051] The side type inlet / outlet water port 1 is arranged in the natural deep and narrow river channel topography formed by the extrusion of the two bank mountains, the front pool 2 is arranged on the side away from the back slope, the bottom elevation of the front pool 2 is lower than the bottom plate elevation of the side type inlet / outlet water port 1, and the front pool 2 constitutes a desilting area; the left side slope bottom of the reverse slope section 3 is overlapped with the right side bottom of the front pool 2; the reverse slope section 3 is an upward inclined slope surface from left to right in the river channel cross section of the lower reservoir, and the right side slope top of the reverse slope section 3 is close to the opposite bank slope 6 and close to the water surface line of the lower reservoir; the sand blocking ridge 4 is arranged on the right side slope top edge of the reverse slope section 3 along the longitudinal direction of the river channel, and is used for blocking the sediment from moving to the side type inlet / outlet water port 1; the sand blocking ridge 4 and the opposite bank slope 6 form the desilting passage 5, the desilting passage 5 is arranged along the longitudinal direction of the river channel, and the front and back ends of the desilting passage 5 are communicated with the lower reservoir sand blocking dam and the lower reservoir river blocking dam respectively; the elevation of the desilting passage 5 is flush with the lower reservoir sand blocking dam downstream reservoir bottom and the lower reservoir river blocking dam upstream reservoir bottom, and the desilting passage 5 is used for guiding the deposited sediment to the reservoir bottom of the lower reservoir river blocking dam;

[0052] In the application, as a specific implementation structure, the side type inlet / outlet water port 1 is constructed by reinforced concrete, and includes a vortex-proof beam section 101, an adjusting section 102, a diffusion section 103 and a gate well section 104 in sequence and communicated in head and tail according to the water pumping flow direction from the opposite bank slope 6 to the back slope;

[0053] The vortex-proof beam section 101 and the adjusting section 102 are equal cross-section water conveying pipelines along the water pumping flow direction; the diffusion section 103 is a variable cross-section water conveying pipeline with gradually reduced cross-section along the water pumping flow direction, and the cross-section size of the diffusion section 103 is the same as that of the adjusting section 102 and the diffusion section 103 connected with each other; the gate well section 104 is an equal cross-section water conveying pipeline along the water pumping flow direction, and the cross-section size of the gate well section 104 is the same as that of the diffusion section 103 and the gate well section 104 connected with each other.

[0054] As a preferred mode, the side type inlet / outlet water port 1 is arranged in parallel with two, and the right ends of the two side type inlet / outlet water ports 1 are communicated with the front pool 2; the left ends of the two side type inlet / outlet water ports 1 are connected by a gate well platform 12 to form a whole.

[0055] The two side type inlet / outlet water ports 1 have a spacing area; on the center measuring line of the spacing area, there are a trash rack maintenance platform 9, a trash rack connecting bridge 10 and a gate well platform lower slope 11 in sequence according to the direction from the front pool 2 to the gate well platform 12.

[0056] In the application, as a specific implementation structure, the front pool 2 is a rectangular reinforced concrete structure, the thickness of the bottom plate is 250 mm; the bottom elevation of the front pool 2 is lower than the bottom plate elevation of the side type inlet / outlet 1, the height difference between the bottom elevation of the front pool 2 and the bottom plate elevation of the side type inlet / outlet 1 is 1.5-2.5 m. The excavation slope ratio of the reverse slope section 3 is 1:4, the slope ratio of the excavation slope on both sides is 1:1.2; the sand blocking ridge 4 is a prism type reinforced concrete structure, the top width is 1 m, the height is 2.5-3 m; the width of the sand discharge channel 5 is 10 m, a layer of cement mortar 7 with a thickness of not less than 5 cm is laid at the bottom as a leveling layer. There is an excavation boundary line 8 between the cement mortar 7 and the underlying riverbed surrounding rock 13.

[0057] Further, the application also includes a secondary dredging facility; the secondary dredging facility is used to handle the sediment accumulation exceeding the design standard of the primary sand discharge structure; the secondary dredging facility includes a dredging device, a long-distance sand discharge pipeline 14 and a short-distance sand discharge pipeline 15;

[0058] The dredging device adopts a cutter suction dredger, which is used to rotate the accumulated sediment in the front pool 2 and the reverse slope section 3 to form slurry;

[0059] The laying path of the short-distance sand discharge pipeline 15 is: on the slope surface of the reverse slope section 3, laid in a zigzag shape from the top of the slope to the bottom of the slope; then reaches the front pool 2, after passing through the bottom of the front pool 2, reaches the trash rack maintenance platform 9, and then reaches the gate well platform below the slope 11 in a straight line after passing through the trash rack connecting bridge 10, and finally reaches the gate well platform 12;

[0060] The laying path of the long-distance sand discharge pipeline 14 is: laid in a straight line on the bottom of the front pool 2, reaches the bottom of the reverse slope section 3, and then is laid in a zigzag shape on the slope surface of the reverse slope section 3 from the bottom of the slope to the top of the slope, then from the top of the reverse slope section 3 through the left abutment of the lower reservoir sand blocking dam, along the reservoir surface of the lower reservoir sand blocking dam, and finally reaches the top of the lower reservoir sand blocking dam.

[0061] Therefore, in the application, the long-distance sand discharge pipeline 14 and the short-distance sand discharge pipeline 15 form a long-distance sand discharge scheme and a short-distance sand discharge scheme respectively, and both schemes are used to transport the slurry formed by the cutter suction dredger through the laid sludge discharge pipeline to the designated place for discharge.

[0062] The application provides a kind of suitable for canyon type riverbed side type inlet / outlet hierarchical dredging and sand discharge system, including primary sand discharge structure and secondary dredging facility, which forms a hierarchical management system together; the method of the application is novel, the effect of dredging and sand discharge is good, construction is simple, cost is low, effectively solves the problem that front edge sediment of sand blocking ridge and reverse slope section sediment cannot be cleaned during the operation of pumped storage power station.

[0063] The application also provides a dredging and desilting method suitable for the grading dredging and desilting system of the side type water inlet / outlet of the canyon type riverbed, which comprises a primary desilting method and a secondary dredging method.

[0064] Step S1, the primary desilting method:

[0065] Step S101, when the lower reservoir is in the pumping state, the water stored in the lower reservoir dam and the lower reservoir sand retaining dam converges into the desilting channel 5 under the action of the terrain, and the main sediment in the water is blocked in the desilting channel 5 under the interception of the sand retaining ridge 4;

[0066] Step S102, after the water containing a small amount of sediment flows into the reverse slope section 3 through the sand retaining ridge 4, the small amount of sediment is deposited on the slope surface of the reverse slope section 3 through the deceleration and energy dissipation of the reverse slope section 3;

[0067] Step S103, after the action of the reverse slope section 3, the water containing a small amount of sediment flows into the front pool 2, and the front pool 2 removes the small amount of sediment in the water;

[0068] The water after removing the sediment flows into the side type water inlet / outlet 1, and is conveyed to the upper reservoir under the action of the water turbine, and the pumping condition is completed;

[0069] Step S104, when the lower reservoir is replenished, the water in the lower reservoir sand retaining dam flows into the lower reservoir through the lower reservoir sand retaining dam, and the deposited sediment in the desilting channel 5 is scoured in the water flow process, so as to guide the deposited sediment to the bottom of the lower reservoir dam, and ensure that the front edge of the sand retaining ridge 4 is free of sediment in the pumping condition;

[0070] Step S2, the secondary dredging method:

[0071] Step S201, when the thickness of the sediment accumulated in the front pool 2 and the reverse slope section 3 exceeds the design standard of the primary desilting structure, the dredging device is started to twist the accumulated sediment in the front pool 2 and the reverse slope section 3, and form the slurry;

[0072] Step S202, under the action of the pump, the slurry is discharged to the designed site through the long distance desilting pipeline 14 and / or the short distance desilting pipeline 15.

[0073] The short distance desilting pipeline 15 discharges the slurry in the reverse slope section 3 and the front pool 2 area to the gate well platform 12 through the desilting pipeline, and the slurry is transported out through the vehicles at the position of the gate well platform 12;

[0074] The long distance desilting pipeline 14 discharges the slurry in the front pool 2 and the slurry in the reverse slope section 3 area to the top of the lower reservoir sand retaining dam through the desilting pipeline, and the slurry is transported out through the vehicles at the position of the top of the lower reservoir sand retaining dam.

[0075] As a further improvement, the invention also studies the relationship between the pre-riffle sediment starting flow velocity of the sediment barrier 4 and the sediment starting particle size , and proposes the expression of formula (1):

[0076] (1)

[0077] Wherein: , are the densities of water and sediment respectively; is the sediment starting particle size; is the acceleration of gravity; is the water depth in the sediment discharge channel 5;

[0078] The pre-riffle flow velocity of the sediment barrier 4 is taken as the sediment starting flow velocity in the sediment discharge channel 5 , and based on the relationship 1, the sediment starting particle size is calculated; therefore, when the actual reservoir bottom sediment particle size is greater than the sediment starting particle size , it indicates that the sediment will not cross the sediment barrier 4 into the reverse slope section 3 and the front pool 2, and the sediment barrier 4 is reasonably set; therefore, the sediment barrier 4 at the outer edge of the side-type intake / outlet 1 is designed to make the pre-riffle section flow velocity lower than the sediment starting flow velocity of the reservoir bottom , so that the effective sediment discharge effect of the sediment discharge channel 5 can be achieved.

[0079] The application discloses a kind of suitable for gorge type riverbed side-type intake / outlet grading dredging and sediment discharge system and method, belong to the dredging and sediment discharge technical field of pumped storage power station engineering.The system includes side-type intake / outlet 1, front pool 2, reverse slope section 3, sediment barrier 4 and sediment discharge channel 5 connected in sequence;The bottom elevation of the front pool 2 is lower than the bottom plate of side-type intake / outlet 1, forms sedimentation area;The reverse slope section 3 outer edge is peripherally provided with a circle of sediment barrier 4, and sediment discharge channel 5 is provided between its end and the opposite bank slope 6, to form a primary sediment discharge structure for dredging sediment of common flood;The method defines the implementation scheme of secondary dredging operation of sediment accumulated in front pool 2 and reverse slope section 3 by using dredging device such as cutter suction dredger.The application solves the sediment accumulation problem of the front edge of side-type intake / outlet and reverse slope section of gorge type riverbed by "structure sediment barrier and guide mainly, mechanical dredging as auxiliary" grading management mode, and guarantees the safety and reliability of long-term operation.

[0080] Below, a certain large-scale hydropower station engineering adopting the technical scheme of the application is taken as an example to further illustrate:

[0081] The total installed capacity of a project is 1400 MW, and the rated power generation water head is 449 m. The water delivery system is composed of a water diversion system and a tailwater system. Both the water diversion system and the tailwater system are arranged in a one-hole two-machine form, and there are two independent water delivery systems (1# and 2#). The side-type intake / outlet 1 of the lower reservoir is composed of a vortex prevention beam section 101, an adjustment section 102, a diffusion section 103, and a gate well section 104, etc. The total length of the side-type intake / outlet 1 is 58.22 m, and the bottom elevation of the side-type intake / outlet 1 is 878.0 m. The topography of the side-type intake / outlet 1: the river bed is squeezed by the mountains on both sides, forming a deep and narrow river channel. To ensure smooth flow of the side-type intake / outlet 1, a tailwater channel is provided at the end of the side-type intake / outlet 1 to connect the lower reservoir. The tailwater channel along the power generation flow direction is composed of a forebay 2, an inverse slope section 3, a sand trap 4, and a desilting channel 5.

[0082] The main flow position of the side-type intake / outlet 1 is at an elevation of 885 m. The flow velocity at the intersection section of the forebay 2 and the inverse slope section 3 is 0.19-0.63 m / s, and the flow velocity at the middle section of the inverse slope section 3 is 0.21-0.84 m / s. The flow velocity at the middle measuring line of the two side-type intake / outlets 1 is smaller, and the flow velocity distribution along the transverse direction of each section is relatively uniform. At an elevation of 895 m, the flow velocity at the intersection section of the forebay 2 and the inverse slope section 3 is -0.04 to -0.16 m / s, the flow velocity at the middle section of the inverse slope section 3 is 0.05-0.16 m / s, and the flow velocity at the two sides of the channel is 0.43-0.57 m / s. The flow velocity distribution along the transverse direction of each section is relatively uniform. When the dead water level of the lower reservoir is 896 m, the starting flow velocity in front of the sand trap 4 is 0.12 m / s. Using the sand starting formula, the sand starting particle size is 0.263 mm. It can be considered that the sand with a particle size greater than 0.263 mm will not start. According to the analysis results of the particle size distribution of the suspended sediment samples at the hydrological station of the power station for many years, the median particle size of the suspended sediment is 0.02 mm, and the average particle size is 0.033 mm, which is less than 0.25 mm. The percentage of sand particle size distribution is about 99.5%. Therefore, it is considered that under the condition of 30-year flood into the reservoir, the lower reservoir does not need to be dredged as a whole. Considering the hydrological characteristics, the operation mode of the power station, the flow pattern of the side-type intake / outlet under the power generation condition, and other factors, most of the sediment in the channel can be carried out of the side-type intake / outlet, and the sediment accumulation in the side-type intake / outlet of the lower reservoir basically will not affect the normal operation of the power station, and separate dredging is not needed.

[0083] During the operation period of the power station, the probability of occurrence of flood greater than 50-year frequency is low. If multiple 30-year or more frequent floods occur during the operation period of the power station or the above frequency floods occur during the maintenance period of the unit, etc., the amount of sediment accumulation exceeds the dead storage capacity, and the whole reservoir needs to be dredged.

[0084] Without considering the part of the sediment carried away during power generation. Taking the 50-year flood as an example to calculate and analyze the sediment accumulation of the side-type intake / outlet:

[0085] The total amount of siltation in the 50-year flood reservoir is 510,000 m 3 The total area of the lower reservoir normal storage level is about 324590.509 m 2 The siltation area of the lower reservoir side type inlet / outlet 1 is about 5763.063 m 2 The area of the front pool 2 and the reverse slope section 3). According to the front pool 2 and the reverse slope section 3 of the lower reservoir side type inlet / outlet, the total amount of siltation of the 50-year flood entering the lower reservoir side type inlet / outlet 1 is conservatively considered to be 0.9055 million m 3 The siltation thickness of the 50-year flood in the lower reservoir side type inlet / outlet 1 is 1.571 m, which is less than the front end dam height 2.25 m.

[0086] The partial desilting scheme of the side type inlet / outlet 1 is as follows: the hydraulic dredging or the cutter suction dredger is used for desilting, the dredger is used for desilting, the CZ650 type dredger can be used, the nameplate yield is 1200 m 3 / h; when the hydraulic dredging is used, the total amount of water and sand to be pumped is 4.53 million m 3 The pumping capacity is about 2 days at the scale of 1000 m 3 / h.

[0087] Through the above technical scheme disclosed by the application, the following beneficial effects are obtained:

[0088] Through the desilting scheme and structure form of the application, most of the sediment brought by the river bed can be smoothly discharged through the desilting channel, and the sediment overflowing the sediment dam is intercepted in the front pool section; the sediment in the front pool and the reverse slope section is sent to the specified position by selecting the corresponding desilting scheme, and the effect of sediment cleaning is further improved.

[0089] The application has the following advantages:

[0090] (1) The "interception-accumulation-discharge" treatment of conventional sediment: the sediment dam is used for preliminary interception, the front pool is used as a sediment collection area, and finally the sediment is smoothly discharged through the desilting channel, forming an efficient and economical conventional sediment treatment closed loop.

[0091] (2) Flexible desilting scheme for over-standard sediment: for the siltation problem caused by over-standard flood, the cutter suction dredger is used for mechanical desilting, and two sets of desilting schemes with long and short distances are provided, and the optimal desilting path can be selected according to the actual engineering conditions to ensure the cleaning effect.

[0092] (3) The comprehensive advantages of the hierarchical system: through the hierarchical cooperation of "structure to guide sand + mechanical dredging of over-standard sand", the sand discharge efficiency under the condition of common flood is ensured, and reliable measures are provided for over-standard flood, the system safety and adaptability are significantly improved while the engineering cost is controlled.

[0093] The above only describes the preferred embodiments of the present application, and it should be noted that those skilled in the art can make several improvements and refinements without departing from the principles of the present application, and these improvements and refinements should be considered as the protection scope of the present application.

Claims

1. A graded dredging and sediment removal system suitable for side-mounted inlets / outlets in canyon-type riverbeds, characterized in that, Includes a primary sand-draining structure; The primary sediment discharge structure is located at the cross-section of the lower reservoir river channel between the lower reservoir dam and the lower reservoir sediment control dam. One side of the cross-section is the rear slope of the inlet / outlet, and the other side is the opposite bank slope (6). In the direction from the rear slope to the opposite bank slope (6), it includes the side inlet / outlet (1), the forebay (2), the reverse slope section (3), the sediment control embankment (4), and the sediment discharge channel (5). The side inlet / outlet (1) is located on the side away from the back slope, and the bottom elevation of the front pool (2) is lower than the bottom elevation of the side inlet / outlet (1), forming a sedimentation zone; the left slope bottom of the reverse slope section (3) overlaps with the right bottom of the front pool (2); the reverse slope section (3) is an upward sloping surface from left to right in the cross-section of the lower reservoir channel, and the right slope top of the reverse slope section (3) is close to the opposite bank slope (6) and near the lower reservoir. Water surface line; the sand-blocking embankment (4) is set along the longitudinal direction of the river channel at the right slope top edge of the reverse slope section (3); the sand-blocking embankment (4) and the opposite bank slope (6) form the sand-discharging channel (5), the sand-discharging channel (5) is set along the longitudinal direction of the river channel, and its front and rear ends are connected to the lower reservoir sand-blocking dam and the lower reservoir river-blocking dam respectively; the elevation of the sand-discharging channel (5) is level with the bottom of the reservoir downstream of the lower reservoir sand-blocking dam and the bottom of the reservoir upstream of the lower reservoir river-blocking dam.

2. The graded dredging and sediment removal system for side-mounted inlets / outlets of canyon-type riverbeds according to claim 1, characterized in that, The side inlet / outlet (1) is located in a natural deep and narrow riverbed formed by the compression of the mountains on both sides.

3. A graded dredging and sediment removal system suitable for side-mounted inlets / outlets of canyon-type riverbeds according to claim 1, characterized in that, The side inlet / outlet (1) is constructed of reinforced concrete and, in the direction of water flow from the opposite bank slope (6) to the rear slope, includes, in sequence, an anti-vortex beam section (101), an adjustment section (102), a diffusion section (103), and a gate well section (104) that are connected end to end. The anti-vortex beam section (101) and the adjustment section (102) are constant cross-section water pipelines along the direction of water flow; the diffuser section (103) is a variable cross-section water pipeline with a gradually decreasing cross-section along the direction of water flow, and its cross-sectional dimensions are the same as those of the adjustment section (102) and the diffuser section (103); the gate well section (104) is a constant cross-section water pipeline along the direction of water flow, and its cross-sectional dimensions are the same as those of the diffuser section (103) and the gate well section (104).

4. A graded dredging and sediment removal system suitable for side-mounted inlets / outlets of canyon-type riverbeds according to claim 3, characterized in that, Two side-mounted inlets / outlets (1) are arranged side by side, and the right ends of the two side-mounted inlets / outlets (1) are connected to the forebay (2); the left ends of the two side-mounted inlets / outlets (1) are connected to form a whole through the gate well platform (12); There is a gap between the two side inlets / outlets (1); along the center line of the gap, from the forebay (2) to the gate well platform (12), there are in sequence a trash rack maintenance platform (9), a trash rack connecting bridge (10) and a slope (11) below the gate well platform.

5. A graded dredging and sediment removal system suitable for side-mounted inlets / outlets of canyon-type riverbeds according to claim 1, characterized in that, The forebay (2) is a rectangular reinforced concrete structure with a bottom plate thickness of 250mm; the elevation difference between the bottom elevation of the forebay (2) and the bottom plate elevation of the side inlet / outlet (1) is 1.5~2.5 meters.

6. A graded dredging and sediment removal system suitable for side-mounted inlets / outlets of canyon-type riverbeds according to claim 1, characterized in that, The excavation slope ratio of the reverse slope section (3) is 1:4, and the slope ratio of the excavation slopes on both sides is 1:1.2; the sand retaining wall (4) is a truncated concrete structure with a top width of 1 meter and a height of 2.5~3 meters; the sand discharge channel (5) is 10 meters wide, and a layer of cement mortar (7) with a thickness of not less than 5 cm is laid at the bottom as a leveling layer.

7. A graded dredging and sediment removal system suitable for side-mounted inlets / outlets of canyon-type riverbeds according to claim 1, characterized in that, It also includes secondary dredging facilities; the secondary dredging facilities include dredging devices, long-distance sand discharge pipelines (14) and short-distance sand discharge pipelines (15); The dredging device is a cutter suction dredger, used to agitate the silt and sand accumulated in the forepool (2) and the reverse slope section (3) to form mud; The laying path of the short-distance sand discharge pipeline (15) is as follows: on the slope surface of the reverse slope section (3), it is laid in a serpentine manner from the top of the slope to the bottom of the slope; then it reaches the forepool (2), after passing the bottom of the forepool (2), it reaches the trash rack maintenance platform (9), and after passing the trash rack connecting bridge (10), it is laid in a straight line on the slope surface of the side slope (11) below the gate well platform, and it reaches the gate well platform (12) the closest. The laying path of the long-distance sand discharge pipeline (14) is as follows: it is laid in a straight line at the bottom of the forebay (2) to the bottom of the reverse slope section (3), and then laid in a serpentine pattern from the bottom to the top of the slope on the slope surface of the reverse slope section (3). Then, it passes through the left shoulder of the lower reservoir sand-blocking dam from the top of the reverse slope section (3), and is laid along the reservoir surface of the lower reservoir sand-blocking dam, finally reaching the top of the lower reservoir sand-blocking dam.

8. A dredging and sediment removal method according to any one of claims 1-7, applicable to a graded dredging and sediment removal system for side-mounted inlets / outlets in canyon-type riverbeds, characterized in that, This includes primary sand removal methods and secondary dredging methods; Step S1, Primary Sand Removal Method: Step S101: When the lower reservoir is in the pumping state, the water stored in the lower reservoir dam and the lower reservoir silt barrier is collected and flows into the silt discharge channel (5) under the action of the topography. Under the interception of the silt barrier (4), the main sediment in the water is blocked in the silt discharge channel (5). In step S102, water containing a small amount of sediment flows into the reverse slope section (3) after crossing the sand-blocking embankment (4); after the deceleration and energy dissipation of the reverse slope section (3), a small amount of sediment is deposited on the slope surface of the reverse slope section (3); In step S103, after the action of the reverse slope section (3), the water containing a small amount of silt flows into the forepool (2), and the forepool (2) removes the small amount of silt in the water by sedimentation; After removing silt, the water flows into the side inlet / outlet (1) and is transported to the upper reservoir by the action of the turbine to complete the pumping operation. Step S104: When replenishing water in the lower reservoir, the water in the lower reservoir's sand-blocking dam flows into the lower reservoir through the sand-blocking dam. During the water flow, the sediment deposited in the sand discharge channel (5) is flushed and the sediment is directed to the bottom of the lower reservoir's dam to ensure that there is no sediment at the front edge of the sand-blocking sill (4) when pumping water. Step S2, Secondary Dredging Method: Step S201: When the siltation thickness in the front pool (2) and the reverse slope section (3) exceeds the design standard of the primary sand discharge structure, the dredging device is activated to agitate the siltation in the front pool (2) and the reverse slope section (3) to form mud. In step S202, the mud is discharged to the design location through a long-distance sand discharge pipeline (14) and / or a short-distance sand discharge pipeline (15) under the action of the pump.

9. A dredging and sediment removal method for a graded dredging and sediment removal system with a side-mounted inlet / outlet in a canyon-type riverbed, as described in claim 8, is characterized in that... The method of sand discharge through the short-distance sand discharge pipeline (15) is as follows: the mud in the reverse slope section (3) and the forebay (2) area is discharged to the gate well platform (12) through the sand discharge pipeline, and then transported out by vehicles at the gate well platform (12); The long-distance sand discharge pipeline (14) is used to discharge sand in the following way: the mud in the forebay (2) and the mud in the reverse slope section (3) are discharged into the top of the sand-blocking dam of the lower reservoir through the sand discharge pipeline, and then transported out by vehicles at the top of the sand-blocking dam of the lower reservoir.

10. A dredging and sediment removal method for a graded dredging and sediment removal system for a canyon-type riverbed side-mounted inlet / outlet, as described in claim 8, is characterized in that... The initial flow velocity of sediment in front of the sand-retaining embankment (4) and sediment starting particle size It has the relation (1): （1） in: , These are the densities of water and sediment, respectively. The initiating particle size of the sediment; It is the acceleration due to gravity; The water depth inside the sand discharge channel (5); The flow velocity at the front section of the sand-blocking embankment (4) is used as the starting velocity of the sediment flow in the sand discharge channel (5). Based on relation (1), the initiation particle size of sediment was calculated. Therefore, when the actual sediment particle size at the bottom of the reservoir is larger than the initial sediment particle size... This indicates that the sediment will not cross the sand-retaining sill (4) and enter the reverse slope section (3) and the forebay (2), and the sand-retaining sill (4) is reasonably set. Therefore, the sand-retaining sill (4) on the outer edge of the side inlet / outlet (1) should be designed so that the flow velocity in front of the sill is lower than the starting flow velocity of the sediment at the bottom of the reservoir. This will enable the sand removal channel (5) to effectively remove sand.

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