Intercepting arrangement method and system for reducing interception fall of steep slope river channel in mountainous area

Abstract

The invention relates to the technical field of water conservancy and hydropower engineering construction guide and closure, in particular to a closure arrangement method and system for reducing the closure fall of a mountain abrupt slope riverway, and the method mainly comprises the steps of non-closure gap section pre-occupation, closure gap section first area occupation, closure gap section second area occupation, closure gap downstream underwater tongue-shaped body platform formation and closure gap section third area occupation closure. By actively adjusting the closure throwing procedure and the particle size of closure throwing materials and arranging closure arrangement of the underwater tongue-shaped body platform, the closure fall is substantially shared by combining the overwater closure embankment and the underwater tongue-shaped body platform, and the problem that closure of double embankments and multiple embankments of the abrupt slope river channel in the mountainous area is difficult to share the closure fall together is solved. The closure hydraulics index is reduced; meanwhile, due to the fact that the elevation of the underwater tongue-shaped body platform is low, the problems that the using amount of closure materials is large, high-strength construction organization is difficult and the closure project investment is large under traditional wide-prop, double-prop or multi-prop closure are solved, and a new mountainous area steep slope river channel closure mode is created.

Description

Technical Field

[0001] The invention belongs to the technical field of diversion and interception in water conservancy and hydropower engineering construction, and relates to an interception arrangement method and system for reducing the interception drop of a steep slope river in a mountainous area. Background Art

[0002] 1. Definition of interception; In the process of building cofferdams on the river, the water flow in the river is cut off and the river water is forced to be diverted to the built diversion and discharge structures or reserved channels to the downstream, which is called diversion. The river diversion methods of water conservancy and hydropower projects at home and abroad can be summarized into two categories: one is the dike diversion method, that is, directly building dikes to divert the water flow in the river; the other is the dike-free dike diversion method, that is, the water flow in the river is cut off without building dikes, such as blasting dike diversion, lowering the gate to dike diversion, etc. The most commonly used dike diversion method for river diversion is dike diversion, which can be mainly summarized into two diversion schemes: flat blocking and vertical blocking. In addition, there is a mixed dike diversion method that combines flat blocking and vertical blocking.

[0003] 2. The commonly used methods of optimizing interception layout to reduce interception drop are as follows; (1) Wide cut-off flow; In order to disperse the drop, some projects use wide dikes to intercept the flow. 3 / s, and the final drop was 1.5 m. The interception dike was originally planned to be 9.0 m wide, but due to the large amount of stone loss, it was later changed to a 76.0 m wide dike, which dispersed the drop and greatly reduced the flow velocity at the dragon mouth. Only 0.5~1.0 t of stone was used to achieve success in the difficult section.

[0004] (2) Double dikes or multiple dikes to intercept the flow; In order to improve the diversion conditions, several foreign projects have adopted measures such as double dikes or multiple dikes for high-drop and large-flow rivers.

[0005] For diversion projects with a final drop of more than 3.5 m, it is appropriate to use double dikes or multiple dikes to block the diversion, which can share the drop and reduce the difficulty of diversion. When double dikes are used, the drop borne by each dike is only equivalent to 60% of the dike interception by a single dike. Due to the increase in water depth, the critical difficult conditions for shallow riverbeds can be avoided before the final stage. When the dike is very long or the number of roads increases a lot, in order to improve the diversion conditions, the dike can also be divided into several dikes in the difficult final stage to form the conditions for diversion by multiple dikes.

[0006] In addition to the common vertical blocking method, double dikes are also used to block the flow in a small number of cases to share the drop. From the perspective of hydraulic conditions, certain conditions must be met between double dikes or multiple dikes, namely, the riverbed between the double dikes or multiple dikes should be a gentle slope, the lower dike should be located within the reflow zone of the upper dike, and the protruding length of the lower dike should exceed the boundary of the reflow zone of the upper dike, otherwise it will be futile or have little effect.

[0007] (3) Riverbed flat-cast bottom protection; When the riverbed has a thick and easily eroded covering layer, in order to avoid erosion, the bottom protection is often thrown flat at the dragon mouth, and large stones are often used for bottom protection. When the covering layer is fine sand, flexible materials (such as firewood rafts, etc.) can also be used, or sand and pebbles can be thrown first, and then large stones can be pressed on top. There is currently no practical formula to calculate the bottom protection range, which is generally determined by model tests. In the preliminary design, the following experience can be referred to: the length of the bottom protection is about 3 to 4 times the maximum water depth downstream of the dragon mouth, and the length of the bottom protection upstream is about 2 times the corresponding water depth, that is, the total length of the upstream and downstream bottom protection is about 5 to 6 times the maximum water depth.

[0008] 3. Problems with the commonly used method of optimizing interception layout to reduce interception drop; At present, in order to ensure that the cofferdam is completed and safely blocked on schedule after the diversion, the dike method is generally used to block the dike at the end of the flood season or the early stage of the dry season. For projects with higher diversion indicators, wide dikes, double dikes or multiple dikes are used for diversion. Large stones, extra-large stones and special diversion materials are used to close the diversion process.

[0009] (1) Wide dike interception: Generally, the top width of the dike is relatively large, which greatly increases the amount of dike throwing materials, and at the same time increases the dike throwing intensity and diversion resource input. The layout conditions of river channels in mountainous areas are poor, and the organization of high-intensity dike construction is difficult, the project investment is large, and the cost is high.

[0010] (2) Double-dike or multi-dike interception is similar to wide-dike interception. On the one hand, it greatly increases the amount of materials used and the intensity of the dikes. Under the condition of narrow river channel layout in mountainous areas, it is difficult to organize the high-intensity dike construction and the project investment is large. On the other hand, double-dike or multi-dike can help each other to share the drop. Certain conditions are required, that is, the riverbed between the upper and lower dikes should be a gentle slope, the lower dike should be located within the return zone of the upper dike, and the protruding length of the lower dike should exceed the edge of the return zone of the upper dike. Otherwise, it will be futile or have little effect. Therefore, this interception method has high cost and low adaptability.

[0011] (3) Conventional riverbed flat-throwing is usually implemented before diversion. It is usually carried out by ship throwing, trestles, etc. The throwing area is large and it is only suitable for plain gentle slope rivers with ship throwing. If the steep slope river channel in mountainous area adopts trestles, the construction of trestles is difficult and the project investment is large. Similarly, this diversion method has high cost and low adaptability. Summary of the invention

[0012] The purpose of the present invention is to provide a method and system for arranging interception to reduce the interception drop of steep slope river channels in mountainous areas, which can solve the technical problems of high cost and low adaptability of existing interception methods. The present invention effectively reduces the difficulty of interception of large flow and high drop river channels in steep slope rivers in mountainous areas, significantly reduces various hydraulic indicators and casting intensity of interception, saves investment in interception projects and difficulty in construction organization, ensures smooth implementation of interception, and creates a new mode of interception of steep slope river channels in mountainous areas.

[0013] The present invention designs a method for reducing the interception drop of steep slope river channels in mountainous areas. Compared with the existing technical solutions, the interception arrangement and method of the underwater tongue-shaped platform are set by actively adjusting the interception throwing program and the particle size of the interception throwing material, effectively reducing the interception difficulty and interception project investment. The present invention mainly includes pre-occupation of non-Longkou section, occupation of Longkou section area 1, occupation of Longkou section area 2, and occupation and closure of Longkou section area 3, which are as follows: Pre-occupation of non-Longkou sections: At the end of the flood season or the early stage of the dry season, pre-occupation of non-Longkou sections is implemented according to the distribution characteristics of the riverbed cover layer. Pre-occupation is mainly based on slag materials, with medium-sized anti-scouring stones set on the upstream side, small anti-scouring stones set on the downstream side, and slag materials set in the middle section of the interception dike; The first area of ​​Longkou section will be occupied. After the pre-occupation is completed, the first area of ​​Longkou section will be occupied. The first area of ​​Longkou section will be occupied mainly with a combination of small stones and medium stones. On the upstream side, a combination of extra-large stones and large stones will be set up for anti-collision, on the downstream side, a combination of large stones and medium stones will be set up for anti-collision, and a combination of small stones and medium stones will be set up in the middle section of the interception dike. The second area of ​​Longkou section was occupied; after the first area of ​​Longkou section was occupied, the second area of ​​Longkou section was occupied. The second area of ​​Longkou section was occupied mainly with large stones. Large-sized throwing materials were set on the upstream side, and large stones were set in the middle section of the interception dike. Since the flow velocity and interception height difference of Longkou section second area were both high, the throwing materials lost on the upstream side gradually formed an underwater tongue-shaped platform on the downstream side of Longkou. The interception height difference was shared by combining the above-water interception dike and the underwater tongue-shaped platform, thus reducing the interception hydraulic index. The third area of ​​the Longkou section has entered the occupation and closure stage; the second area of ​​the Longkou section used the underwater tongue-shaped platform on the downstream side to successfully pass the diversion and enter the difficult section for closure, and entered the third area of ​​the Longkou section for occupation and closure. With the continuous decline of various diversion hydraulic indicators of Longkou, the throwing materials of the third area of ​​the Longkou section were gradually adjusted from extra-large stones to large stones, then from large stones to medium stones, and finally from medium stones to small stones, and finally the closure was completed.

[0014] As a preferred option, during the pre-occupation process of the non-Longkou section, the pre-occupation length of the upstream side anti-impact medium stone and the downstream side anti-impact small stone is always slightly longer than the pre-occupation length of the middle section slag material, to prevent the middle section slag material from being directly washed along the water flow and backflowing to wash the middle section slag material.

[0015] As the preferred option, during the occupation of the first area of ​​the Longkou section, the occupation length of the upstream side anti-impact extra-large stone to large stone combination and the downstream side anti-impact large stone to medium stone combination is always slightly longer than the occupation length of the middle section small stone to medium stone combination, to prevent the middle section small stone to medium stone combination from being directly washed along the water flow and backflow washing away the middle section small stone to medium stone combination.

[0016] As a preferred solution, the throwing material includes a concrete tetrahedron, a concrete cube, a reinforced concrete three-dimensional frame, a reinforced concrete frame, and a hollow tetrahedron; the diameter and weight of each throwing material are calculated according to the following formulas: ; Where: d-the converted diameter of the thrown material, i.e. the diameter of a sphere, m; W-the weight of the thrown material, kg; v max - Maximum flow rate, the average flow rate of the dragon mouth axis is taken for calculation, ms -1 ; k-comprehensive stability coefficient; g-gravitational acceleration, taken as 9.81ms -2 ; r m - Bulk density of thrown material, 2.6 tm for stone -3 , concrete block takes 2.4 tm -3 ; r- bulk density of water, take 1.0 tm -3 .

[0017] Furthermore, the impact distance of each thrown material is estimated by converting it according to the following empirical formula: ; Combining equations (1) to (2), calculate the impact distance L of the thrown material according to (3), (4) or (5); Where: L-thrust, m; W-weight of thrown material, kg; v-average vertical velocity, ms -1 ; v0-surface velocity of water flow, ms -1 ; H-water depth, m; d-diameter of the thrown material, converted into the diameter of a sphere, m.

[0018] Furthermore, according to the action of water flow and the stabilization mechanism of the casting materials, the entry point of each casting material is selected in combination with the impulse distance of the casting materials, and the stabilization point of the casting materials on the river bottom is determined, thereby determining the specific position of the underwater tongue-shaped platform formed on the downstream side of Longkou.

[0019] As a preferred solution, the lower part of the underwater tongue-shaped platform is padded with medium stones, and the upper part is protected with a combination of large and extra-large stones, which can roughen the bottom and protect the dragon mouth covering layer, and is used to improve the stability of the interception block.

[0020] As a preferred solution, the underwater tongue-shaped platform adopts vertical blocking and throwing. There are no dikes on both sides of the underwater tongue-shaped platform to constrain the water flow, so the water flow is easy to diffuse, which is used to reduce the flow velocity and the difficulty of interception.

[0021] As a preferred solution, the elevation of the underwater tongue-shaped platform is lower than that of the above-water intercepting dike, which facilitates the passage of water and shares the interception drop with the above-water intercepting dike.

[0022] The present invention also designs a layout system based on the interception layout method for reducing the interception drop of steep slope river channels in mountainous areas, including an above-water interception dike arranged on one side of the riverbed and an underwater tongue-shaped platform arranged on the other side of the riverbed. The above-water interception dike and the underwater tongue-shaped platform are connected under water, and the elevation of the underwater tongue-shaped platform is lower than that of the above-water interception dike, and the two jointly share the interception drop. The above-water interception dike includes upstream anti-scouring riprap, middle section riprap, anti-seepage wall, and downstream anti-scouring riprap. The middle section riprap is located on both sides of the anti-seepage wall. The above-water interception dike selects riprap of different sizes according to different dragon mouth occupation stages. The underwater tongue-shaped platform is gradually formed on the downstream side of Longkou by the anti-scouring riprap lost from the upstream side. The lower part of the underwater tongue-shaped platform is padded with medium stones, and the upper part is protected by a combination of large and extra-large stones to improve the stability of the interception blocks.

[0023] Beneficial effects of the present invention: Compared with the traditional interception solution, the technical solution of the present invention has the following technical effects: (1) Since the riverbed gradient of steep slope rivers in mountainous areas is large, the solution of the present invention is to set up an underwater tongue-shaped platform, which is essentially to share the interception drop by combining the above-water interception dike + the underwater tongue-shaped platform, thereby solving the problem that double dikes and multiple dikes are difficult to share the interception drop in steep slope rivers in mountainous areas, and reducing the interception hydraulic indicators; at the same time, since the underwater tongue-shaped platform has a low elevation, it avoids the problems of large amount of interception materials, difficulty in high-intensity construction organization, and large investment in interception projects under traditional wide dikes, double dikes or multiple dikes.

[0024] (2) The establishment of an underwater tongue-shaped platform has the following advantages, which can help to further reduce the difficulty of interception: first, the tongue-shaped platform downstream of the dragon mouth can protect the dragon mouth cover layer; second, the underwater tongue-shaped platform plays a role in cushioning and roughening the bottom, thereby improving the stability of the interception block; third, there are no dikes on both sides of the underwater tongue-shaped platform to constrain the water flow, so the water flow is easy to diffuse, which can effectively reduce the flow velocity and thus reduce the difficulty of interception.

[0025] (3) The underwater tongue-shaped platform strictly adopts the method of vertical blocking and throwing, which avoids the problems of difficult construction organization and large engineering investment in the process of using a trestle to level the riverbed and lay the foundation.

[0026] (4) The present invention is applied to Xulong Hydropower Station. According to the results of the interception model test, under the conditions of designed interception flow (1263m 3 / s), when there is no underwater tongue-shaped platform, the maximum drop of the dragon mouth is 12.4m, the maximum flow rate is 11.5m, and the total throwing volume is 194,000m 3 , the maximum casting intensity on a single bank is 1113m 3 / h, the site needs to further widen and increase the construction road by about 20km, and it needs to prepare tetrahedral strings and large stone strings of about 20,000m 3 After setting up the underwater tongue-shaped platform, the maximum drop of the dragon mouth is 8.2m, the maximum flow rate is 10.1m, and the total throwing volume is 156,000m 3 , the maximum casting strength of a single bank is 655m 3 / h, the site needs to further widen and increase the construction road by about 8km, and it needs to prepare tetrahedral strings and large stone strings of about 5,000m 3 .

[0027] In summary, the application of the technical solution of the present invention reduces interception indicators such as the dragon mouth drop and the maximum flow velocity, saves about 25% of the total casting volume, and reduces direct investment by 7.15 million yuan. In addition, due to the reduced interception risk, the feasibility of interception is improved, which is about 1 month ahead of the feasibility study period. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1a This is a schematic diagram of the plan view of the dike method to block the flow.

[0029] Figure 1b This is a schematic diagram of the AA section of the dike method to block the flow.

[0030] Figure 1c This is a schematic diagram of the BB cross-section of the dike method to block the flow.

[0031] Figure 2 This is a typical layout diagram of the diversion dike.

[0032] Figure 3 It is a common type of artificial throwing material in the present invention.

[0033] Figure 4 This is the plan layout of the traditional diversion dike.

[0034] Figure 5 This is the MM cross-section of the traditional intercepting dike.

[0035] Figure 6 This is a three-dimensional schematic diagram of a traditional dike.

[0036] Figure 7 It is a plan view of the intercepting dike and underwater tongue-shaped platform of the present invention.

[0037] Figure 8 It is a cross-sectional view of the intercepting dike and underwater tongue-shaped platform NN of the present invention.

[0038] Fig. 9 It is a three-dimensional schematic diagram of the intercepting dike and underwater tongue-shaped platform of the present invention.

[0039] Description of reference numerals: 1- riverbed, 2- axis of anti-seepage wall, 3- upstream anti-scouring riprap, 4- middle section riprap of intercepting dike, 5- downstream anti-scouring riprap, 6- anti-seepage wall, 7- topographic line, 8- underwater tongue-shaped platform, 8.1- medium stone, 8.2- combination of large stone and extra large stone, 11- diversion building, 12- intercepting dike, 121- axis of intercepting dike, 13- dragon mouth, 14- river bank, 15- backflow area, 16- direction of occupation, 17- upstream dike, 18- axis of cofferdam, 19- rockfill, 20- weathered sand, 21- slag mixture, 22- transition layer, 23- curtain grouting. DETAILED DESCRIPTION

[0040] In order to make the technical problems solved by the present invention, the technical solutions adopted and the technical effects achieved clearer, the technical solutions of the present invention are further described below in conjunction with the accompanying drawings and through specific embodiments. It is understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for the convenience of description, only the parts related to the present invention are shown in the accompanying drawings, not all.

[0041] The invention relates to a method and system for arranging an interception flow to reduce the interception drop of a steep slope river in a mountainous area, and is applicable to the technical field of water conservancy and hydropower engineering that adopts the dike-retaining method for interception. The technical scheme of the invention mainly solves the problems of high hydraulic index, great interception difficulty, high casting intensity, and difficulty in organizing high-intensity interception construction in a steep slope river in a mountainous area, and proposes an interception flow arrangement and method by actively adjusting the interception casting procedure, the particle size of the interception casting material, and setting an underwater tongue-shaped platform, which effectively reduces the difficulty of intercepting a large flow and high-drop river in a steep slope river in a mountainous area, significantly reduces various hydraulic indexes and casting intensity of interception, saves interception project investment and construction organization difficulty, ensures smooth implementation of interception, and creates a new mode for interception of a steep slope river in a mountainous area.

[0042] With the application of large-scale loading and transportation machinery and the development of vertical blocking and interception theory and interception technology, in order to meet the requirement of timely completion of the cofferdam after interception and safe water retention, the steep slope river channel in mountainous areas generally chooses to use the method of vertical blocking and interception at the end of the flood season or the beginning of the dry season. The method of vertical blocking and interception is to throw the interception material from both banks or one bank into the riverbed, gradually narrowing the riverbed until the river is completely cut off. Figure 1a-1c First, dikes 12 are built on both sides of the riverbed to gradually narrow the riverbed. This process is called occupation. The occupation direction 16 is as shown in FIG. Figure 1bAs shown; a diversion building 11 is arranged on one side of the riverbed, and a certain gap is reserved between the diversion building 11 and the river bank 14 to facilitate the flow of water. The direction of the water flow is as follows Figure 1a As shown by the arrow, the intercepting dike 12 on one side of the riverbed is connected to the diversion building 11, a reflow area 15 is formed in the intercepting dike 12, and a dragon mouth 13 is formed in the section between the intercepting dikes 12 on both sides, and then the dragon mouth is blocked at the right time to close the dike; in order to solve the leakage of the dike, anti-seepage facilities (sealing) must be set up on the water-facing surface of the dike immediately. Therefore, the entire dike method blocking and intercepting process includes occupation, bottom protection and head wrapping, closing and sealing. After interception, the dike is raised and thickened to form a cofferdam.

[0043] The intercepting dike is generally a part of the cofferdam. According to the number and arrangement of dikes, it can be divided into single dike, double dike and multiple dikes. Single dike is usually arranged on the backwater side of the upstream cofferdam, while double dike and multiple dike are usually arranged in the upstream and downstream cofferdams. Figure 2 It includes an upstream dike, a cofferdam body, and a dike for intercepting dikes. The interior of the upstream dike 17 is composed of rockfill 19; the cofferdam body includes an anti-seepage wall 6, weathered sand 20, a slag mixture 21, and a transition layer 22. Curtain grouting 23 is injected into the anti-seepage wall 6 to prevent water from penetrating into the cofferdam body. The transition layer 22 is adjacent to the dike for intercepting dikes 12; the cofferdam axis 18 and the dike axis 121 are as shown in FIG. Figure 2 shown.

[0044] In order to improve the interception conditions, several foreign projects have adopted double dikes or multiple dikes for high-drop and high-flow rivers. For example, Project A (final drop 1.9m), Project B (final drop 3.86m) and Project C (final drop 1.4m) all adopted double dikes for vertical blocking. Among them, the interception flow of Project B reached 8100 m 3 / s, the final drop is 3.86 m. The original design flow rate is 17000m 3 / s, considering that the final drop of 7.0 m is shared by four dikes 1, 2, 3, and 4. In actual interception, dikes 2 and 4 are used alternately, each sharing about 1 / 2 of the water head, so that only rocks with a maximum weight of 23.0t are used to successfully intercept the flow.

[0045] For the interception project with a final drop of more than 3.5 m, it is appropriate to use double dikes or multiple dikes to block the flow, which can share the drop and reduce the difficulty of interception. When double dikes are used, the drop borne by each dike is only equivalent to 60% of the interception by a single dike. Due to the increase in water depth, the critical difficult conditions before the final stage can be avoided for shallow riverbeds. When the final drop is less than 3.5 m, it is appropriate to use a single dike to block the flow. The construction organization is relatively simple, with less auxiliary equipment and more economical. When the dike is very long or the road is increased a lot, in order to improve the interception conditions, the dike can also be divided into several dikes in the difficult final stage to form the conditions for multiple dike interception. The distance between dikes should be such that the flow velocity between dikes is greatly reduced. In various interception examples, the distance between dikes is mostly within 100 m. For some interception projects with high drop and large flow, the above number (distance) seems too short. For double dikes occupied by opposite river banks, the above figures can be shortened.

[0046] In addition to the common use of vertical blocking to occupy the double dikes, a small number of double dikes are also used to block horizontally to share the height difference. For example, a certain project also uses the method of horizontal blocking of the upper dike and vertical blocking of the lower dike. However, if the upper dike is blocked by vertical blocking and the lower dike is blocked horizontally, not only will the height difference not be evenly shared, but the concentrated water flow of the upper dike may also destroy the lower dike, so it is not adopted.

[0047] The characteristics of interception schemes for typical water conservancy and hydropower projects at home and abroad are shown in Table 1.

[0048] Table 1 Characteristics of interception schemes for typical water conservancy and hydropower projects at home and abroad

[0049] Figures 4 to 6 It is a schematic diagram of the arrangement of traditional interception dikes. There are topographic lines 7 on both sides of the riverbed 1. The water interception dike is arranged on one side of the riverbed 1. The water interception dike consists of upstream anti-scouring riprap 3, middle section riprap 4, anti-seepage wall 6, and downstream anti-scouring riprap 5. The width of the upstream anti-scouring riprap 3 is A1, the width of the middle section riprap 4 of the interception dike is B1, the middle section riprap 4 of the interception dike is divided into two symmetrical parts with the anti-seepage wall axis 2 as the symmetry center, and the width of the downstream anti-scouring riprap 5 is C1.

[0050] Figures 7 to 9Schematic diagram of the arrangement of the intercepting dike of the present invention, with topographic lines 7 on both sides of the riverbed 1, the above-water intercepting dike arranged on one side of the riverbed 1, and the underwater tongue-shaped platform 8 arranged on the other side of the riverbed 1, the above-water intercepting dike and the underwater tongue-shaped platform 8 connected under the water, the elevation of the underwater tongue-shaped platform 8 is lower than the elevation of the above-water intercepting dike, and the two share the interception drop; the above-water intercepting dike is composed of upstream anti-scouring riprap 3, middle section riprap 4, anti-seepage wall 6, and downstream anti-scouring riprap 5; the width of the upstream anti-scouring riprap 3 is A2, the width of the middle section riprap 4 of the intercepting dike is B2, the middle section riprap 4 of the intercepting dike is divided into two symmetrical parts with the anti-seepage wall axis 2 as the symmetry center, and the width of the downstream anti-scouring riprap 5 is C2.

[0051] Compared with the existing technical solutions, the present invention effectively reduces the difficulty of interception and the investment in interception projects by actively adjusting the interception and casting program and the particle size of the interception and casting materials and setting the interception arrangement and method of the underwater tongue-shaped platform.

[0052] The present invention provides a method for arranging a diversion flow to reduce the diversion drop of a steep slope river in a mountainous area. The technical scheme of the present invention mainly includes pre-occupation of a non-Longkou section, occupation of a first area of ​​a Longkou section, occupation of a second area of ​​a Longkou section, formation of an underwater tongue-shaped platform downstream of the Longkou section, occupation and closure of a third area of ​​a Longkou section, etc. The specific steps are as follows: (1) Pre-occupation of the non-Longkou section. At the end of the flood season or the beginning of the dry season, the pre-occupation of the non-Longkou section is implemented first. The pre-occupation is generally based on slag. The anti-scouring riprap 3 set on the upstream side is medium-sized anti-scouring stone, and the anti-scouring riprap 5 set on the downstream side is small anti-scouring stone. The middle section 4 of the interception dike is equipped with slag.

[0053] During the pre-occupation process of the non-Longkou section, the pre-occupation length of the upstream anti-collision medium stone and the downstream anti-collision small stone is always slightly longer than the pre-occupation length of the middle section slag material, to prevent the middle section slag material from being directly washed along the water flow and backflowing to wash the middle section slag material.

[0054] (2) Occupation of the first area of ​​the Longkou section. After the pre-occupation is completed, the occupation of the first area of ​​the Longkou section will begin. The occupation of the first area of ​​the Longkou section is generally based on small stones to medium stones. The anti-scouring riprap 3 set on the upstream side is a combination of extra-large stones to large stones for anti-scouring, and the anti-scouring riprap 5 set on the downstream side is a combination of large stones to medium stones for anti-scouring. The middle section 4 of the interception dike is a combination of small stones to medium stones.

[0055] During the occupation of the first area of ​​the Longkou section, the length of the upstream side's super-large stone to large stone combination and the downstream side's large stone to medium stone combination was always slightly longer than the length of the middle section's small stone to medium stone combination, preventing the middle section's small stone to medium stone combination from being directly washed along the water flow and backflow washing away the middle section's small stone to medium stone combination.

[0056] (3) Occupation of the second area of ​​the Longkou section. After the occupation of the first area of ​​the Longkou section was completed, the occupation of the second area of ​​the Longkou section began. The occupation of the second area of ​​the Longkou section was generally based on large stones. The anti-scouring riprap 3 set on the upstream side was a large-sized artificial throwing material ~ extra-large stone. Large stones were set in the middle section of the interception dike. Since the flow velocity and interception drop of the second area of ​​the Longkou section were both high, the throwing materials lost on the upstream side gradually formed an underwater tongue-shaped platform on the downstream side of the Longkou. The interception drop was shared by the combined water interception dike and the underwater tongue-shaped platform, reducing the interception hydraulic indicators.

[0057] ① Common types of artificial throwing materials such as Figure 3 As shown in the figure, (a) concrete tetrahedron; (b) concrete cube; (c) reinforced concrete three-dimensional frame; (d) reinforced concrete frame; (e) hollow tetrahedron.

[0058] Common types and sizes of artificial throwing materials are shown in Table 2.

[0059] Table 2 Common types and sizes of artificially thrown materials

[0060] ②The diameter and weight of each artificially thrown material shall be calculated according to the following formula: ; Where: d-the converted diameter of the thrown material, i.e. the diameter of a sphere, m; W-the weight of the thrown material, kg; v max - Maximum flow rate, the average flow rate of the dragon mouth axis is taken for calculation, ms -1 ; k-comprehensive stability coefficient, the comprehensive stability coefficient is purely experimental data; g-gravitational acceleration, taken as 9.81 ms -2 ; r m - Bulk density of thrown material, 2.6 tm for stone -3 , concrete block takes 2.4tm -3 ; r- bulk density of water, take 1.0 tm -3 .

[0061] According to the water flow effect and the stability mechanism of the cast material, the selection of the cast material and the verification of the head-wrapped anti-collision material can be controlled according to the stopping and starting conditions respectively. The weight of the interception cast material can be calculated according to formulas (1) and (2), and preliminarily selected with reference to similar engineering practice data, and finally determined based on the results of the hydraulic model cast test.

[0062] ③ When throwing stones in flowing water, the distance between the stable point of the stone on the riverbed and the point where it enters the water is called the throw distance. The throw distance is related to the flow parameters and the roughness of the riverbed. Due to the complexity of factors and the great differences in the topography of the riverbed surface, the throw distance of each artificial throwing material is estimated by converting it according to the following empirical formula: ; Combining equations (1) to (2), calculate the impact distance L of the thrown material according to (3), (4) or (5); Where: L-thrust distance, m; W-weight of thrown material, kg; v -Vertical average velocity, ms -1 ; v 0 -Surface velocity of water, ms -1 ; H-water depth, m; d-diameter of the thrown material, converted into the diameter of a sphere, m.

[0063] According to the action of water flow and the stabilization mechanism of the casting materials, combined with the calculated impact distance of the casting materials, the entry point of each artificial casting material is selected, and the stabilization point of the casting material on the river bottom is determined, thereby determining the specific position of the underwater tongue-shaped platform formed on the downstream side of Longkou.

[0064] (4) The formation of an underwater tongue-shaped platform 8 downstream of Longkou. The second area of ​​the Longkou section is a difficult section in the process of interception, occupation and closure. Even if large stones are used as the main casting, the hydraulic indicators such as the flow velocity and interception drop of Longkou are relatively high. The risk of large stones being lost downstream will inevitably occur during the occupation process. During the occupation process at this stage, the interception casting procedure and the diameter of the casting materials are actively adjusted according to the hydraulic indicators of the Longkou area, so that the lost casting materials form an underwater tongue-shaped body downstream of Longkou in a targeted manner. The lower part of the underwater tongue-shaped body is cushioned with medium stones 8.1, and the upper part is protected with a combination of large stones and extra-large stones 8.2. As the tongue-shaped body extends downward, it begins to accumulate and gradually forms a tongue-shaped platform 8 on the downstream side of the dike. When the tongue-shaped body extends to a certain length, it no longer extends. At this time, due to the existence of the tongue-shaped platform 8, the dragon mouth drop begins to disperse along the direction of water flow. In addition, the tongue-shaped platform 8 plays a role in bottoming and roughening, the stability of the stone blocks is improved, and there is no dike constraint on both sides of the tongue-shaped body. The water flow diffuses, effectively reducing the flow velocity, thereby reducing the difficulty of interception and allowing it to pass through the difficult section smoothly.

[0065] (5) Longkou Section Area 3 is occupied and closed. After using the underwater tongue-shaped platform on the downstream side to reduce the interception height and hydraulic indicators, Longkou Section Area 2 can smoothly pass the interception and enter the difficult section of closure, entering the Longkou Section Area 3 occupation and closure stage. As the hydraulic indicators of Longkou continue to decline, the throwing materials in Longkou Section Area 3 are gradually adjusted from extra-large stones to large stones, then from large stones to medium stones, and finally from medium stones to small stones, and finally the closure is completed.

[0066] The present invention arranges an underwater tongue-shaped platform, which essentially shares the interception drop by combining the above-water interception dike + the underwater tongue-shaped platform, thereby solving the problem that double dikes and multiple dikes on steep slope rivers in mountainous areas are difficult to share the interception drop, and reduces the interception hydraulic indicators; at the same time, due to the low elevation of the underwater tongue-shaped platform, the problems of large amount of interception materials, difficult high-intensity construction organization and large investment in interception projects in traditional wide dikes, double dikes or multiple dikes are avoided.

[0067] In addition, the setting of an underwater tongue-shaped platform has the following advantages, which is conducive to further reducing the difficulty of interception: first, the tongue-shaped platform downstream of Longkou can protect the Longkou covering layer; second, the underwater tongue-shaped platform plays a role in bottom padding and roughening, thereby improving the stability of the interception stone; third, there are no dikes on both sides of the underwater tongue-shaped platform to constrain the water flow, so the water flow is easy to diffuse, which can effectively reduce the flow velocity and thus reduce the difficulty of interception.

[0068] Strictly speaking, the underwater tongue-shaped platform adopts vertical blocking and throwing, which avoids the problems of difficult construction organization and large engineering investment in the use of building a trestle to level the riverbed and lay the foundation.

[0069] The present invention is applied to Xulong Hydropower Station. According to the results of the interception model test, under the condition of designed interception flow (1263m 3 / s), when there is no underwater tongue-shaped platform, the maximum drop of the dragon mouth is 12.4m, the maximum flow rate is 11.5m / s, and the total throwing volume is 194,000m 3 , the maximum casting intensity on a single bank is 1113m 3 / h, the site needs to further widen and increase the construction road by about 20km, and it needs to prepare tetrahedral strings and large stone strings of about 20,000m 3 After setting up the underwater tongue-shaped platform, the maximum drop of the dragon mouth is 8.2m, the maximum flow rate is 10.1 m / s, and the total throwing volume is 156,000 m 3 , the maximum casting strength of a single bank is 655m 3 / h, the site needs to further widen and increase the construction road by about 8km, and it needs to prepare tetrahedral strings and large stone strings of about 5,000m 3 The comparison is shown in the following table:

[0070] In summary, the application of the technical solution of the present invention reduces interception indicators such as the dragon mouth drop and the maximum flow velocity, saves about 25% of the total casting volume, and reduces direct investment by 7.15 million yuan. In addition, due to the reduced interception risk, the feasibility of interception is improved, which is about 1 month ahead of the feasibility study period.

[0071] It should be understood that the specific order or hierarchy of steps in the process disclosed by the present invention is an example of an exemplary method. Based on design preferences, it should be understood that the specific order or hierarchy of steps in the process can be rearranged without departing from the scope of protection of the present disclosure. The attached method claims provide the elements of the various steps in an exemplary order and are not intended to be limited to the specific order or hierarchy described.

[0072] The present invention also provides a layout system based on the interception layout method for reducing the interception drop of steep slope river channels in mountainous areas, comprising an above-water interception dike arranged on one side of the riverbed and an underwater tongue-shaped platform arranged on the other side of the riverbed, wherein the above-water interception dike and the underwater tongue-shaped platform are connected under water, the elevation of the underwater tongue-shaped platform is lower than that of the above-water interception dike, and the two jointly share the interception drop; The above-water interception dike includes upstream anti-scouring riprap, middle section riprap, anti-seepage wall, and downstream anti-scouring riprap. The middle section riprap is located on both sides of the anti-seepage wall. The above-water interception dike selects riprap of different sizes according to different dragon mouth occupation stages. The underwater tongue-shaped platform is gradually formed on the downstream side of Longkou by the anti-scouring riprap lost from the upstream side. The lower part of the underwater tongue-shaped platform is padded with medium stones, and the upper part is protected by a combination of large and extra-large stones to improve the stability of the interception blocks.

[0073] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for arranging a river interception to reduce the interception drop of a steep slope river in a mountainous area, characterized in that: The following steps are included: Pre-occupation of non-Longkou sections: At the end of the flood season or the early stage of the dry season, pre-occupation of non-Longkou sections is implemented according to the distribution characteristics of the riverbed cover layer. Pre-occupation is mainly based on slag materials, with medium-sized anti-scouring stones set on the upstream side, small anti-scouring stones set on the downstream side, and slag materials set in the middle section of the interception dike; The first area of ​​Longkou section will be occupied. After the pre-occupation is completed, the first area of ​​Longkou section will be occupied. The first area of ​​Longkou section will be occupied mainly with a combination of small stones and medium stones. On the upstream side, a combination of extra-large stones and large stones will be set up for anti-collision, on the downstream side, a combination of large stones and medium stones will be set up for anti-collision, and a combination of small stones and medium stones will be set up in the middle section of the interception dike. The second area of ​​Longkou section was occupied; after the first area of ​​Longkou section was occupied, the second area of ​​Longkou section was occupied. The second area of ​​Longkou section was occupied mainly with large stones. Large-sized throwing materials were set on the upstream side, and large stones were set in the middle section of the interception dike. Since the flow velocity and interception height difference of Longkou section second area were both high, the throwing materials lost on the upstream side gradually formed an underwater tongue-shaped platform on the downstream side of Longkou. The interception height difference was shared by combining the above-water interception dike and the underwater tongue-shaped platform, thus reducing the interception hydraulic index. The third area of ​​the Longkou section has entered the occupation and closure stage; the second area of ​​the Longkou section used the underwater tongue-shaped platform on the downstream side to successfully pass the diversion and enter the difficult section for closure, and entered the third area of ​​the Longkou section for occupation and closure. With the continuous decline of various diversion hydraulic indicators of Longkou, the throwing materials of the third area of ​​the Longkou section were gradually adjusted from extra-large stones to large stones, then from large stones to medium stones, and finally from medium stones to small stones, and finally the closure was completed.

2. A method for arranging interception for reducing interception drop of steep slope river in mountainous area according to claim 1, characterized in that: During the pre-occupation process of the non-Longkou section, the pre-occupation length of the upstream anti-collision medium stone and the downstream anti-collision small stone is always slightly longer than the pre-occupation length of the middle section slag material, to prevent the middle section slag material from being directly washed along the water flow and backflowing to wash the middle section slag material.

3. The method for arranging a river interception for reducing the interception drop of a steep slope river in a mountainous area according to claim 1, characterized in that: During the occupation of the first area of ​​the Longkou section, the occupation length of the super-large stone to large stone combination on the upstream side and the large stone to medium stone combination on the downstream side is always slightly longer than the occupation length of the small stone to medium stone combination in the middle section, preventing the small stone to medium stone combination in the middle section from being directly washed along the water flow and the backflow from washing away the small stone to medium stone combination in the middle section.

4. The method for arranging a river interception for reducing the interception drop of a steep slope river in a mountainous area according to claim 1, characterized in that: The throwing materials include concrete tetrahedrons, concrete cubes, reinforced concrete stereo frames, reinforced concrete frames, and hollow tetrahedrons; the diameter and weight of each throwing material are calculated according to the following formulas: ； Where: d-the converted diameter of the thrown material, i.e. the diameter of a sphere, m; W-the weight of the thrown material, kg; v max - Maximum flow rate, the average flow rate of the dragon mouth axis is taken for calculation, ms -1 ; k-comprehensive stability coefficient; g-gravitational acceleration, taken as 9.81 ms -2 ; r m - Bulk density of thrown material, 2.6 tm for stone -3 , concrete block takes 2.4 tm -3 ; r- bulk density of water, take 1.0 tm -3 .

5. A method for arranging interception for reducing interception drop of steep slope river in mountainous area according to claim 4, characterized in that: The impact distance of each thrown material is estimated by conversion according to the following empirical formula: ； Combining equations (1) to (2), calculate the impact distance L of the thrown material according to (3), (4) or (5); Where: L-thrust distance, m; W-weight of thrown material, kg; v -Vertical average velocity, ms -1 ; v 0 -Surface velocity of water, ms -1 ; H-water depth, m; d-diameter of the thrown material, converted into the diameter of a sphere, m.

6. A method for arranging interception for reducing interception drop of steep slope river in mountainous area according to claim 5, characterized in that: According to the action of water flow and the stabilization mechanism of the casting materials, combined with the impact distance of the casting materials, the entry point of each casting material is selected to determine the stabilization point of the casting material on the river bottom, thereby determining the specific position of the underwater tongue-shaped platform formed on the downstream side of Longkou.

7. A method for arranging a river interception for reducing the interception drop of a steep slope river in a mountainous area according to any one of claims 1 to 6, characterized in that: The bottom of the underwater tongue-shaped platform is padded with medium stones, and the top is protected with a combination of large and extra-large stones, which can roughen the bottom and protect the dragon mouth covering layer, and are used to improve the stability of the interception block stone.

8. A method for arranging interception for reducing interception drop of steep slope river in mountainous area according to claim 7, characterized in that: The underwater tongue-shaped platform adopts vertical blocking and throwing, and there is no dike constraint on both sides of the underwater tongue-shaped platform, so the water flow is easy to diffuse, which is used to reduce the flow velocity and the difficulty of interception.

9. A method for arranging interception for reducing interception drop of steep slope river in mountainous area according to claim 8, characterized in that: The elevation of the underwater tongue-shaped platform is lower than that of the intercepting dike on the water, so it is convenient for water to pass through, and it shares the intercepting drop with the intercepting dike on the water.

10. A layout system based on a method for reducing the interception drop of a steep slope river in a mountainous area, characterized in that: It includes an above-water interception dike arranged on one side of the riverbed and an underwater tongue-shaped platform arranged on the other side of the riverbed. The above-water interception dike and the underwater tongue-shaped platform are connected under water. The elevation of the underwater tongue-shaped platform is lower than that of the above-water interception dike, and the two share the interception drop. The above-water interception dike includes upstream anti-scouring riprap, middle section riprap, anti-seepage wall, and downstream anti-scouring riprap. The middle section riprap is located on both sides of the anti-seepage wall. The above-water interception dike selects riprap of different sizes according to different dragon mouth occupation stages. The underwater tongue-shaped platform is gradually formed on the downstream side of Longkou by the anti-scouring riprap lost from the upstream side. The lower part of the underwater tongue-shaped platform is padded with medium stones, and the upper part is protected by a combination of large and extra-large stones to improve the stability of the interception blocks.

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