Navigation water flow condition optimization method for branch flow convergence section of navigation channel

Abstract

The invention relates to the field of navigation channel engineering, in particular to a navigation water flow condition optimization method for a navigation channel branch flow and confluence section, and the method comprises the steps: setting a corresponding physical model of the navigation channel branch flow and confluence section; engineering measures such as broadening a tributary port, sloping left and right sides, setting a stepped first stilling pool, designing height difference of the stilling pool and designing corresponding steps are performed based on the physical model, whether the transverse flow velocity exceeds a standard value or not is tested under an adverse working condition, the physical model is optimized and modified based on a test result, and through a plurality of groups of contrast tests, the transverse flow velocity of the stilling pool is determined. The scheme with the optimal result is selected as the navigation water flow condition optimization scheme of the branch-flow convergence section of the navigation channel by comprehensively considering engineering technicality, economy, coordination of engineering measures and environment and the like by taking measures such as arrangement of a solid flow separation embankment, a grit chamber and a 1: 4 abrupt slope.

Description

Technical Field

[0001] The invention relates to the field of waterway engineering, and in particular to a method for optimizing navigation flow conditions of a tributary inflow and confluence section of a waterway. Background Art

[0002] In a river system, the intersection of the main stream and tributaries is the inflow section, which presents complex hydrodynamic characteristics due to the convergence of water flow. The inflow section not only carries the superposition of water from both sides, but also is accompanied by the exchange of sediment, pollutants and heat, which has a significant impact on the local ecological environment and water quality. In particular, lateral flow velocity often occurs at the inflow, which is perpendicular to the mainstream direction and distributed along the width of the river, causing the water flow to form complex vortices and turbulence near the intersection.

[0003] Cross-currents increase the complexity and risk of vessel maneuvers, making the river potentially unnavigable. Cross-currents may force vessels to deviate from their intended routes, especially in curved or narrow waterway sections, increasing the risk of collisions with shores or obstacles. In addition, unstable flow patterns can also affect vessel stability and navigation safety, especially in adverse weather conditions.

[0004] Therefore, engineering measures are needed to optimize the water flow conditions at the confluence section to meet the navigation needs of the river. Summary of the invention

[0005] The purpose of the present invention is to provide a method for optimizing the navigable water flow conditions of the confluence section of a waterway tributary in order to solve the problem that the confluence section of a main channel and a tributary in the prior art usually has a lateral flow velocity, which increases the complexity and risk of ship maneuvering and may make the river unnavigable. Engineering measures are needed to optimize the water flow conditions of the confluence section to meet the navigation needs of the river.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] A method for optimizing navigable water flow conditions at a tributary confluence section of a waterway comprises the following steps:

[0008] S1. Construct a physical model of the waterway tributary confluence section;

[0009] S2. Conducting a navigation flow condition test based on the physical model and setting the first scheme;

[0010] Widen the tributary mouth, excavate to the bottom elevation, and slope the left and right sides with a slope ratio of 1:2; set the first stilling pool at the intersection of the main and branch rivers. The first stilling pool is a stepped stilling pool. Arc-shaped retaining walls are set on both sides of the inlet and the outlet of the first stilling pool to form a trumpet mouth; the first stilling pool includes level one, level two, and level three. The level one stilling pool is 3-4m higher than the level two stilling pool, and the level two stilling pool is 3-4m higher than the level three stilling pool. Steps are set at the end of each level stilling pool, and the steps are 1-2m higher than the corresponding level stilling pool; the outlet of the first stilling pool is sloped downward at a ratio of 1:15, and the bottom of the slope is connected to the second stilling pool. The level three steps are 5-6m higher than the second stilling pool. The second stilling pool is sloped upward with a height difference of 1-2m;

[0011] Setting at least one working condition, testing the first solution and obtaining corresponding results, including whether the lateral flow velocity exceeds the specification value;

[0012] S3. Based on the test results of the first scheme, if the lateral flow velocity exceeds the standard value, the navigation flow condition optimization test is carried out on the physical model to set the second scheme, the third scheme and the fourth scheme;

[0013] The second scheme adds a physical flow barrier on the basis of the first scheme, and the physical flow barrier is set at the throat where the main and tributary rivers meet; the second scheme is tested under the above working conditions and the corresponding results are obtained, including whether the lateral flow velocity exceeds the standard value;

[0014] The third scheme is based on the first scheme. A sedimentation pool is dug at the outlet of the third-level stilling pool. The third-level stilling pool is 2-3m higher than the sedimentation pool. A step is set at the tail of the sedimentation pool and the slope is lowered at 1:15. The bottom of the slope connects to the second stilling pool. The third step is 5-6m higher than the second stilling pool. The second stilling pool slopes upward with a height difference of 1-2m. The third scheme is tested under the above working conditions and the corresponding results are obtained, including whether the lateral flow velocity exceeds the specification value.

[0015] The fourth scheme is based on the first scheme, with the gentle slope of 1:15 changed to a steep slope of 1:4, and the rest remains unchanged; the fourth scheme is tested under the above working conditions and the corresponding results are obtained, including whether the lateral flow velocity exceeds the standard value;

[0016] Compare the test results of the second, third and fourth options, and select the best result as the recommended option.

[0017] A method for optimizing the navigable flow conditions of a tributary inflow and confluence section of a waterway as described in the present invention is adopted. By setting a physical model of the corresponding tributary inflow and confluence section of the waterway, engineering measures such as widening the tributary mouth, sloping the left and right sides, setting a stepped first energy dissipation pool, designing the height difference of the energy dissipation pool and designing the corresponding steps are taken based on the physical model. Under unfavorable working conditions, it is tested to determine whether the lateral flow velocity exceeds the standard value. Based on the test results, the physical model is optimized and modified. Through multiple groups of control tests, such as setting a physical flow barrier, a sedimentation tank, a 1:4 steep slope and other measures, the scheme with the best results is selected as the optimization scheme for the navigable flow conditions of the tributary inflow and confluence section of the waterway from comprehensive considerations such as engineering technology, economy and coordination between engineering measures and the environment.

[0018] As a preferred technical solution of the present invention, in step S1, the model adopts a normal fixed-bed river engineering model, which meets the similarity conditions of geometry, gravity, resistance and continuity.

[0019] As a further preferred technical solution of the present invention, in step S1, the river channel model is made of cement mortar using a section panel method, and the energy dissipation pool is made of rubber board and cement mortar.

[0020] As a further preferred technical solution of the present invention, in step S1, the model main stream is 2.5-3km long, the tributary is 1-1.5km long, the confluence angle of the tributary into the main stream is 40°-60°, the main stream has 50-60 sections with a spacing of 42-60m, the tributaries have 50-60 sections with a spacing of 17-30m, and 5-10 sections are arranged at the intersection of the main stream and the tributaries, and the spacing is set according to the terrain characteristics.

[0021] As a further preferred technical solution of the present invention, in step S2, the radius of the arc-shaped retaining wall at the inlet of the first stilling pool is 15-20m, and the radius of the arc-shaped retaining wall at the outlet of the first stilling pool is 15-20m.

[0022] As a further preferred technical solution of the present invention, in step S2, the width of the first energy dissipation pool is 50-60m and the length is 70-80m; the first-level energy dissipation pool is 22m long, the bottom elevation is 36.5m, and the first-level step is 2m long; the second-level energy dissipation pool is 22m long, the bottom elevation is 33.5m, and the second-level step is 2m long; the third-level energy dissipation pool is 24m long, the bottom elevation is 30.5m, and the third-level step is 1m long.

[0023] As a further preferred technical solution of the present invention, in step S2, the bottom elevation of the second energy dissipation pool is 26.2 m, and the second energy dissipation pool is sloped upward to a top elevation of 27.7 m.

[0024] As a further preferred technical solution of the present invention, in step S2, one working condition is that the tributary flow is the most unfavorable to navigation conditions, and the 20-year flood flow is selected for simulation, and finally determined to be Q = 532m 3 / s, the main stream flow is selected according to the flood standard of once in five years, and finally determined to be Q = 340m 3 / s.

[0025] As a further preferred technical solution of the present invention, in step S3, the physical flow-isolating dike of the second solution is a straight flow-isolating dike with a length of 30-40m and a width of 1.5-2m, and the shortest distance between the flow-isolating dike and the boundary of the waterway is 6.5m;

[0026] The third option sets a sedimentation tank length of 40-50m and a bottom elevation of 27.7m.

[0027] As a preferred technical solution of the present invention, in the test, the water level is measured by a probe; the surface flow velocity is measured by a surface particle imaging system, and the vertical flow velocity is measured by a propeller flow meter.

[0028] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0029] The method for optimizing the navigable flow conditions of a tributary inflow and confluence section of a waterway described in the present invention sets a physical model of the corresponding tributary inflow and confluence section of the waterway, and based on the physical model, takes engineering measures such as widening the tributary mouth, sloping the left and right sides, setting a stepped first energy dissipation pool, designing the height difference of the energy dissipation pool and designing the corresponding steps, and tests are conducted under unfavorable conditions to determine whether the lateral flow velocity exceeds the standard value, and the physical model is optimized and modified based on the test results. Through multiple groups of control tests, such as setting up a physical flow barrier, a sedimentation tank, a 1:4 steep slope and other measures, the scheme with the best results is selected as the optimization scheme for the navigable flow conditions of the tributary inflow and confluence section of the waterway from comprehensive considerations such as engineering technology, economy and coordination between engineering measures and the environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a schematic diagram of the plan layout of the first scheme;

[0031] Figure 2 This is the longitudinal section of the stilling pool of the first scheme;

[0032] Figure 3 This is the contour map of the transverse flow velocity under working condition 1 of the first scheme;

[0033] Figure 4 This is the contour map of the transverse flow velocity under working condition 2 of the first scheme;

[0034] Figure 5 This is a schematic diagram of the plan layout of the second scheme;

[0035] Figure 6 This is the contour map of the transverse flow velocity under working condition 1 of the second scheme;

[0036] Figure 7 This is a schematic diagram of the plan layout of the third scheme;

[0037] Figure 8 This is the longitudinal section of the stilling pool of the third scheme;

[0038] Fig. 9 This is the contour map of the transverse flow velocity under working condition 1 of the third scheme;

[0039] Fig.10 This is a schematic diagram of the layout of the fourth scheme;

[0040] Fig.11 This is the longitudinal section of the stilling pool of the fourth scheme;

[0041] Fig.12 This is the contour map of the lateral flow velocity in condition 1 of the fourth scheme. DETAILED DESCRIPTION

[0042] The present invention is further described in detail below in conjunction with test examples and specific implementation methods. However, this should not be understood as the scope of the above subject matter of the present invention being limited to the following embodiments, and all technologies realized based on the content of the present invention belong to the scope of the present invention.

[0043] Unless otherwise specified, in the description of the specific embodiments of the present invention, the terms indicating the orientation or position relationship such as "up", "down", "left", "right", "center", "inside", "outside", etc. are all expressions based on the orientation or position relationship shown in the drawings, or are the orientation or position relationship when the invented product / equipment / device is usually used. These terms of orientation or position relationship are only for the convenience of describing the scheme of the present invention or simplifying the description in the specific embodiments, so as to facilitate the technicians to quickly understand the scheme, and do not indicate or imply that a specific device / component / element must have a specific orientation, or be constructed and operated in a specific position relationship, and therefore cannot be understood as a limitation on the present invention.

[0044] In addition, if the terms "horizontal", "vertical", "overhanging", "parallel" and the like appear, it does not mean that the corresponding devices / components / elements are required to be absolutely horizontal or vertical or overhanging or parallel, but may be slightly tilted or have deviations. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but may be slightly tilted. Alternatively, it can be simplified to mean that the corresponding devices / components / elements are set in directions such as "horizontal", "vertical", "overhanging", "parallel", etc., and can have an error / deviation of ±10% relative to the corresponding direction setting, more preferably an error / deviation within ±8%, more preferably an error / deviation within ±6%, more preferably an error / deviation within ±5%, and more preferably an error / deviation within ±4%. As long as the corresponding device / component / element is within the error / deviation range, it can still achieve its role in the scheme of the present invention.

[0045] In addition, the expressions “first”, “second”, “third”, etc., which appear in the terms, are merely used to distinguish the description of the same or similar components and should not be understood as emphasizing or implying the relative importance of specific components.

[0046] In addition, in the description of the embodiments of the present invention, "several", "plurality" and "a number" represent at least 2. It can be any number such as 2, 3, 4, 5, 6, 7, 8, 9, and even more than 9.

[0047] In addition, in the description of the technical solution of the present invention, unless otherwise clearly specified / defined / restricted, the terms "set", "install", "connect", "connected", "provided with", "laid", and "arranged" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection, and can be welding, riveting, bolting, threading, and other commonly used connection means in the field. This connection can be a mechanical connection, an electrical connection, or a communication connection; it can be a direct connection, or an indirect connection through an intermediate medium, and it can be the internal connection of two elements.

[0048] In the related art, the inflow section of the main and tributary rivers usually has a lateral flow velocity, which increases the complexity and risk of ship operation, resulting in the river being unnavigable. Engineering measures are needed to optimize the water flow conditions of the inflow section to meet the navigation needs of the river. Figures 1 to 12 To elaborate.

[0049] Example 1

[0050] The method for optimizing the navigable flow conditions of a tributary confluence section of a waterway according to the present invention comprises the following steps:

[0051] Step 1: Construct a physical model of the waterway tributary inflow section.

[0052] 1. Model design

[0053] The model uses a plane scale λ L =50, vertical scale λ H =50. According to the basic principle of water flow similarity in river engineering models, similarity conditions such as geometry, gravity, resistance and continuity must be met, thus the following similarity scale can be obtained:

[0054] Plane scale: λ L =50; vertical scale: λ H =50

[0055] Flow rate scale:

[0056] Water flow time scale:

[0057] Flow rate scale:

[0058] Roughness scale: (Using Manning's roughness formula)

[0059] According to the test data, the tributary flow velocity during the low water level period is 0.6-1.5 m / s, and the minimum water depth is about 2 m. The minimum Reynolds number of the model is Re M =1200; It is estimated that the model water flow during the flood period meets the requirement of entering the turbulent state (Reynolds number>1000). The hydrological combination of this embodiment is a flood condition in the tributary, so it can be considered that the model meets the similarity requirements of the turbulent state.

[0060] 2. Model making

[0061] The river channel model is made of cement mortar using the section panel method. According to the terrain characteristics and importance, the spacing of the tributary sections is about 0.3m, the spacing of the main stream sections is about 1m, and the spacing of the sections in the intersection of the main and branch streams is about 0.36m. The conductor is laid by a total station, and the theodolite and steel ruler are checked. The plane control triangle closure error is less than ±5". The section plane and elevation drawing errors are both less than 0.5mm, the installation error plane is controlled within ±1.0cm, and the elevation error is controlled within ±0.5mm. In addition, local sections, cross sections, etc. are used to carefully shape the local complex terrain such as convex mouths, rocks, reefs, stone beams, deep pools, etc. to ensure the geometric similarity of the model.

[0062] The studied river section has water-related structures such as energy dissipation basins. The model is made of rubber board, cement mortar, etc., and is made strictly in accordance with geometric similarity on the plane. A small deviation in surface roughness has a negligible impact on the test results.

[0063] The flow control system mainly includes a water reservoir, a water pump, a motor, an electromagnetic flow meter, a computer and other control software, and can deliver a maximum flow rate of 300L / s.

[0064] The water level is measured by a probe with an accuracy of 0.1mm. One water gauge is arranged at each water gauge section of the tributary, and at least three water gauges are arranged at each water gauge section of the main stream, namely left, middle and right, so as to accurately control and read the water level and grasp the gradient between the bank and the center of the river. The water gauge spacing is 250-400m, with an average spacing of about 350m (model 7.0m).

[0065] The flow velocity is mainly measured by the surface particle imaging system, which can quickly, accurately and comprehensively measure the surface flow field. The vertical flow velocity is mainly measured by the propeller flow meter.

[0066] According to the results of the feasibility study, the comprehensive roughness of this river section is 0.03-0.04. The vegetation on both sides of each tributary river section is lush, the shape resistance is large, and the local resistance is difficult to calculate accurately. The comprehensive roughness of the feasibility study is only used as a reference for the initial roughening. The actual roughening is determined based on the accuracy of the water surface line verification. According to the verification test, the use of cement mortar roughening can basically meet the similar requirements of various levels of water surface lines.

[0067] 3. Model scope

[0068] The main stream of the model is 2.5-3km long, the tributary is 1-1.5km long, and the angle of inflow from the tributary to the main stream is 40°-60°. In this embodiment, the tributary can be selected to be about 1.1km long, the main stream is about 2.6km long, the main stream is about 1.4km below the tributary confluence entrance, and about 1.2km above the tributary entrance. The angle of inflow from the tributary to the main stream is about 45°. The model range can ensure the reasonable distribution of the flow entering the model, and the inlet has sufficient length and curved sections to allow the water flow entering the test section at each period to be fully adjusted: the outlet is relatively straight, ensuring the similarity of the model tailwater flow state.

[0069] The model has 50-60 sections arranged in the main stream (marked by DM), with a spacing of 42-60m, 50-60 sections arranged in the tributaries (marked by HCS), with a spacing of 17-30m, and 5-10 sections arranged at the intersection of the main and tributaries, with the spacing set according to the terrain characteristics. In this embodiment, the optional model has a total of 113 sections arranged, of which 56 sections are arranged in the tributaries, with a section spacing of 15m; 51 sections are arranged in the main stream, with a section spacing of 50m (the spacing of the main stream sections at the intersection of the main and tributaries and the bend section is encrypted); 6 sections are arranged at the intersection of the main and tributaries, and the section spacing is set according to the terrain characteristics, with an average of about 15m.

[0070] Step 2: Conduct navigation flow condition tests based on the physical model.

[0071] 1. Layout of the first option

[0072] (1) Tributary section

[0073] Widen the tributary mouth and excavate from section HCS1 to HCS3 to the bottom elevation of 38.5m; the elevation of the left and right slopes is 43m, and the slope ratio is 1:2.

[0074] (2) The first energy dissipation pool is designed at the intersection of the trunk and branch. The first energy dissipation pool is a stepped energy dissipation pool.

[0075] The intersection sections are: HCS3-HCS19.

[0076] The two sides of the first stilling pool inlet are connected by an arc-shaped retaining wall with a radius of 15-20m from section HCS2 to HCS5. In this embodiment, 18.6m can be selected, and the retaining wall elevation is 43m, wherein the elevation of the step between sections HCS4 and HCS6 is 40m; the two sides of the first stilling pool outlet are connected by an arc-shaped retaining wall with a radius of 15-20m from section HCS14 to HCS15. In this embodiment, 20m can be selected, and the retaining wall elevation is 43m; forming a bell-mouth.

[0077] The width of the first stilling pool is 50-60m, and the length is 70-80m. In this embodiment, the width of the first stilling pool can be 54.4m, and the total length is 73m. The first stilling pool includes the first level, the second level, and the third level. The first level stilling pool is 3-4m higher than the second level stilling pool, and the second level stilling pool is 3-4m higher than the third level stilling pool. A step is set at the end of each level stilling pool, and the step is 1-2m higher than the corresponding level stilling pool; in this embodiment, the first level stilling pool can be selected from the section HCS6 to HCS7, 22m long, the bottom elevation is 36.5m, and the first level step is 2m long; the second level stilling pool is from the section HCS9 to HCS10, 22m long, the bottom elevation is 33.5m, and the second level step is 2m long; the third level stilling pool is from the section HCS12 to HCS13, 24m long, the bottom elevation is 30.5m, and the third level step is 1m long.

[0078] The outlet of the first stilling pool is sloped downward from HCS14 to HCS16 at a ratio of 1:15. The three steps are 5-6m higher than the second stilling pool. In this embodiment, the slope bottom elevation can be 26.2m. From section HCS16 to HCS17, the second stilling pool with a bottom elevation of 26.2m is sloped upward, with a height difference of 1-2m. In this embodiment, the slope from section HCS17 to HCS18 can be sloped to a top elevation of 27.7m. Figure 1 and Figure 2 shown.

[0079] 2. Determine the navigation flow conditions according to the proposed test conditions

[0080] Condition 1: From the perspective of the most unfavorable navigation conditions, the tributary flow is selected for simulation of a flood flow with a return period of 20 years, and the final value is Q = 532m 3 / s, the main stream flow is selected according to the flood standard of once in five years, and finally determined to be Q = 340m 3 / s, the tailwater level is determined by interpolation of the corresponding pile number of the main stream's five-year flood level, and is finally determined to be 35.32m.

[0081] Condition 2: The tributary is selected with a flood flow rate of once in five years, Q = 297m 3 / s, the main stream flow is Q = 0m 3 / s, and the tailwater level was finally determined to be 34m.

[0082] The flow velocity was measured using the XKVMS series surface flow field measurement system developed by the Southwest Water Transport Engineering Science Research Institute, and the water level was read using a water level probe. The flow conditions such as the surface flow velocity distribution, flow pattern, and water surface fluctuations of the confluence area were observed.

[0083] (1) Analysis of the experimental results of working condition 1 shows that the confluence in the channel at the intersection area increases as it approaches the left boundary of the channel, but it is still relatively small overall. This is because the energy dissipation basin processes the water flow, and the angle between the centerline of the channel at the intersection of the main and branch rivers and the direction of the tributary flow is relatively small, and there are no complex water flow conditions in the channel.

[0084] The energy dissipation basin treated the water from the tributary, but under the first solution, the lateral velocity was too high. The maximum lateral velocity was measured to be 0.49 m / s within the waterway, located in the left area of ​​the waterway at section DM34. There was also an area with excessive velocity on the left side of the waterway at sections DM30-DM32, which was an ellipse with a lateral dimension of 38.15 m and a longitudinal dimension of approximately 29.1 m. The area with excessive velocity in the waterway at sections DM33-DM35 almost occupied the entire waterway, with a lateral dimension of 57.26 m and a longitudinal dimension of approximately 47.12 m. In summary, the lateral velocity distribution does not meet the requirements of the specification. For details, see Figure 3 shown.

[0085] (2) Analysis of the experimental results of working condition 2 shows that since there is no flow in the mainstream under this working condition, some backflow will occur at section DM25-DM30 after the tributary merges into the mainstream. However, after the energy dissipation of the stilling pool, the backflow velocity is small, with a maximum value of 0.27 m / s. The flow velocity in the waterway of the intersection area is within 2 m / s, and the flow state of the rest is good. The angle between the centerline of the waterway at the intersection area and the direction of the tributary flow is also relatively small.

[0086] After the energy dissipation of the stilling basin, the lateral velocity within the channel exceeds the standard value in part, with the maximum value of 0.35m / s, located on the left side of the channel boundary line of section DM29. The lateral scale of the area exceeding the standard value is 21.07m, and the longitudinal scale is 22.18m. The lateral velocity distribution basically meets the standard requirements. Figure 4 shown.

[0087] Condition 1: Flow pattern and water surface fluctuation at the confluence section. In order to further observe the flow pattern and water surface fluctuation at the confluence section, the section DM25 with large water level fluctuation in the confluence area and the downstream section DM29 were selected to set up observation points. The water level fluctuation difference of the confluence section DM25 is about 33cm, and the water level fluctuation difference of the DM29 section is about 31.3cm. The flow pattern of the water in the channel is good and relatively stable.

[0088] Compared with condition 1, observation points were set up in the same section in condition 2. The water level fluctuation difference at section DM25 was about 17.89 cm, and the water level fluctuation difference at section DM29 was 33.54 cm. The water flow in the channel was good and relatively stable.

[0089] 3. Statistics of channel flow velocity at the confluence section of the first scheme

[0090] Table 1 shows the flow velocity in the channel from section DM26 to DM36 in working condition 1 of the first scheme, among which the maximum combined velocity is 1.79 m / s, occurring at section DM35; the minimum value is 0.16 m / s, occurring at section DM28; the maximum lateral velocity is 0.49 m / s, occurring at section DM34 (intersection area), and the minimum lateral velocity is 0.01 m / s, occurring at section DM26.

[0091] Table 1 Statistics of channel flow velocity in the first scheme of working condition 1 of the waterway tributary inflow and confluence section (m / s)

[0092]

[0093]

[0094]

[0095] Table 2 shows the flow velocity in the channel from section DM26 to DM36 in working condition 2 of the first scheme, among which the maximum combined velocity is 1.11 m / s, occurring at section DM31; the minimum value is 0.03 m / s, occurring at section DM30; the maximum lateral velocity is 0.28 m / s, occurring at section DM29 (intersection area), and the minimum lateral velocity is 0.0 m / s, occurring at section DM26.

[0096] Table 2 Statistics of channel flow velocity in the first scheme of working condition 2 of the waterway tributary inflow and confluence section (m / s)

[0097]

[0098]

[0099]

[0100] 4. Analysis of test results

[0101] The first plan adopted the method of using energy dissipation basins to treat the water flow of tributaries. However, since the terrain of the tributaries showed typical mountain river characteristics, the incoming water velocity was fast. When the upstream water flow was large, the lateral flow velocity in the confluence area exceeded the standard value by a large margin, and the first plan needed to be further modified.

[0102] Step 3: Conduct navigation flow condition optimization test on the physical model.

[0103] 1. Layout of the second option

[0104] On the basis of the first scheme, a solid flow barrier is added to reduce the lateral flow velocity in the confluence area of ​​the main and branch rivers. The length of the straight flow barrier is 30-40m, and the width is 1.5-2m. In this embodiment, the optional length is 37.4m, the width is 2m, and the top elevation is 27.7m; and the shortest distance between the flow barrier and the channel boundary is about 6.5m. The plan layout is shown in the figure below. Figure 5 shown.

[0105] 2. Determine the navigation flow conditions according to the proposed test conditions

[0106] Working condition 1: Same as working condition 1 of the first scheme.

[0107] (1) Under the action of the solid flow barrier, the combined velocity of the water flow in the channel is generally small, and the water flow velocity in the confluence area is within 2 m / s. The angle between the centerline of the channel and the flow direction of the tributary in the confluence area is relatively small, and there is no complex water flow pattern in the channel.

[0108] (2) Although the overflow dam has handled the water flow, the lateral velocity is still too high under this scheme. The maximum lateral velocity in the waterway is 0.44 m / s, located on the right side of the DM35 section. There is also an area with excessive velocity in the center of the DM35 section, with a lateral dimension of about 51.22 m and a longitudinal dimension of about 47.1 m. The lateral velocity distribution does not meet the requirements of the specification. Figure 6 shown.

[0109] 3. Statistical table of channel flow velocity at the confluence section of the second scheme

[0110] Table 3 shows the flow velocity in the channel from section DM26 to DM36 in working condition 1 of the second scheme, among which the maximum combined velocity is 1.97 m / s, occurring at section DM34; the minimum value is 0.24 m / s, occurring at section DM26; the maximum lateral velocity value is 0.44 m / s, occurring at section DM35; and the minimum lateral velocity value is 0.0 m / s, occurring at sections DM27 and DM29.

[0111] Table 3 Statistics of channel flow velocity in the second scheme of working condition 1 of the waterway tributary inflow and confluence section (m / s)

[0112]

[0113]

[0114]

[0115] 4. Analysis of test results

[0116] Compared with the first option, the second option did not produce an all-round improvement in the channel conditions of the confluence section after changing to a physical dike. The distribution of the lateral flow velocity did not meet the requirements of the specification, so the ship's route would be hindered to a certain extent under the second option.

[0117] Step 4: Conduct navigation flow condition optimization test on the physical model.

[0118] 1. Layout of the third option

[0119] The third scheme cancels the solid flow barrier, and digs a sedimentation pool with a bottom elevation of 27.7m and a length of 40-50m at the outlet of the third-level stilling pool of the second scheme, and slopes at a ratio of 1:15 from the tail of the sedimentation pool (elevation of 28.7m), with a bottom elevation of 26.2m. In this embodiment, a 50m long sedimentation pool can be selected. From section HCS16 to HCS17 is the second stilling pool with a bottom elevation of 26.2m, and slopes from section HCS17 to HCS18, with a top elevation of 27.7m. The plan layout is shown in the figure below. Figure 7 As shown in Figure 2, the longitudinal section of the stilling pool is as follows: Figure 8 shown.

[0120] 2. Determine the navigation flow conditions according to the proposed test conditions

[0121] Working condition 1: Same as working condition 1 of the first scheme.

[0122] (1) Under the action of the stilling basin and the sedimentation basin, the combined velocity of the water flow in the channel becomes larger than that in the second scheme, and the angle between the centerline of the channel and the direction of the tributary flow in the confluence area of ​​the main and branch rivers is also larger, and the flow pattern of the water flow in the channel is more chaotic.

[0123] (2) Due to the energy dissipation effect of the stilling basin on the water flow, the lateral flow velocity in the channel of the intersection area has been more significantly improved. There is no area in the channel of the intersection area that exceeds the standard value. The maximum value is 0.24m / s, located on the left side of the channel at section DM34. In summary, ships can navigate safely. Details are as follows Fig. 9 shown.

[0124] 3. Statistics of channel flow velocity at the confluence section of the third scheme

[0125] Table 4 shows the flow velocity in the navigation channel from section DM26 to DM36 in working condition 1 of the third scheme, among which the maximum combined velocity is 1.97 m / s, occurring at section DM34; the minimum value is 0.40 m / s, occurring at section DM26; the maximum lateral velocity value is 0.24 m / s, occurring at section DM34; and the minimum lateral velocity value is 0.0 m / s, occurring at sections DM26, DM27, DM28, DM29, DM30 and DM35.

[0126] Table 4 Statistics of channel flow velocity in the third scheme of working condition 1 of the waterway tributary inflow and confluence section (m / s)

[0127]

[0128]

[0129]

[0130] 4. Analysis of test results

[0131] Compared with the second option, the water flow conditions in the waterway of the confluence area of ​​the third option have been significantly improved, and the distribution of lateral flow velocity meets the requirements of the specifications. This option is basically qualified.

[0132] Step 5: Conduct navigation flow condition optimization test on the physical model.

[0133] 1. Layout of the fourth option

[0134] The fourth plan changes the gentle slope of 1:15 to a steep slope of 1:4 based on the first plan, and the rest remains unchanged. The elevation at the foot of the slope is 26.2m. The plan layout is as follows Fig.10 As shown in Figure 2, the longitudinal section of the stilling pool is as follows: Fig.11 shown.

[0135] 2. Determine the navigation flow conditions according to the proposed test conditions

[0136] Working condition 1: Same as working condition 1 of the first scheme.

[0137] (1) Due to the energy dissipation effect, the combined velocity in the confluence section has been significantly improved, the angle between the centerline of the channel and the mainstream is small, and there is no complex water flow pattern in the channel.

[0138] (2) After setting the steep slope of 1:4, the lateral flow velocity has been greatly improved. There is no area beyond the range value in the channel of the confluence section, and it can be safely navigated. Fig.12 shown.

[0139] In order to further observe the flow pattern and water surface fluctuation of the confluence section, observation points were set up at the confluence section DM25 of the model and the downstream section DM29 near the left bank. The water level fluctuation difference at section DM25 was about 33.54cm, and the water level fluctuation difference at section DM29 was about 44.72cm. The flow pattern of the water in the channel was good and relatively stable.

[0140] 3. Statistics of channel flow velocity at the confluence section of the fourth scheme

[0141] Table 6 shows the flow velocity of the channel from section DM26 to DM36 in the fourth scheme, working condition 1, where the maximum combined velocity is 1.58 m / s, which occurs at section DM36, and the minimum is 0.23 m / s, which occurs at section DM34. The maximum transverse velocity is 0.29 m / s, which occurs at section DM35, while the minimum transverse velocity is 0.00 m / s, which occurs at sections DM28, DM30 to DM31, DM33 to DM34, and section DM36.

[0142] Table 6 Statistics of channel flow velocity in the fourth scheme of working condition 1 of the waterway tributary inflow and confluence section (m / s)

[0143]

[0144]

[0145]

[0146] 4. Analysis of test results

[0147] With a 1:4 steep slope and energy dissipation pool, the river direction was optimized, the distance from the tail of the first energy dissipation pool to the intersection area was increased, and the kinetic energy of the water flowing into the main stream was weakened to a certain extent. The lateral water flow velocity of Condition 1 was significantly improved, and the lateral flow velocity reached the navigation standard with a good flow state. Therefore, the fourth plan can be recommended.

[0148] The method for optimizing the navigable flow conditions of a tributary confluence section of a waterway described in this embodiment sets a physical model of the corresponding tributary confluence section of the waterway, and based on the physical model, takes engineering measures such as widening the tributary mouth, sloping the left and right sides, setting a stepped first energy dissipation pool, designing the height difference of the energy dissipation pool and the corresponding step design. Under unfavorable working conditions, it is tested to determine whether the lateral flow velocity exceeds the standard value, and the physical model is optimized and modified based on the test results. Through multiple groups of control tests, such as setting a physical flow barrier, a sedimentation tank, a 1:4 steep slope and other measures, the scheme with the best results is selected as the optimization scheme for the navigable flow conditions of the tributary confluence section of the waterway from comprehensive considerations such as engineering technology, economy and coordination between engineering measures and the environment.

[0149] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for optimizing navigation flow conditions at a tributary confluence section of a waterway, characterized in that: The following steps are involved: S1. Construct a physical model of the waterway tributary confluence section; S2. Conducting a navigation flow condition test based on the physical model and setting the first scheme; Widen the tributary mouth, excavate to the bottom elevation, and slope the left and right sides with a slope ratio of 1:2; set the first stilling pool at the intersection of the main and branch rivers. The first stilling pool is a stepped stilling pool. Arc-shaped retaining walls are set on both sides of the inlet and the outlet of the first stilling pool to form a trumpet mouth; the first stilling pool includes level one, level two, and level three. The level one stilling pool is 3-4m higher than the level two stilling pool, and the level two stilling pool is 3-4m higher than the level three stilling pool. Steps are set at the end of each level stilling pool, and the steps are 1-2m higher than the corresponding level stilling pool; the outlet of the first stilling pool is sloped downward at a ratio of 1:15, and the bottom of the slope is connected to the second stilling pool. The level three steps are 5-6m higher than the second stilling pool. The second stilling pool is sloped upward with a height difference of 1-2m; Setting at least one working condition, testing the first solution and obtaining corresponding results, including whether the lateral flow velocity exceeds the specification value; S3. Based on the test results of the first scheme, if the lateral flow velocity exceeds the standard value, the navigation flow condition optimization test is carried out on the physical model to set the second scheme, the third scheme and the fourth scheme; The second scheme adds a physical flow barrier on the basis of the first scheme, and the physical flow barrier is set at the throat where the main and tributary rivers meet; the second scheme is tested under the above working conditions and the corresponding results are obtained, including whether the lateral flow velocity exceeds the standard value; The third scheme is based on the first scheme. A sedimentation pool is dug at the outlet of the third-level stilling pool. The third-level stilling pool is 2-3m higher than the sedimentation pool. A step is set at the tail of the sedimentation pool and the slope is lowered at 1:

15. The bottom of the slope connects to the second stilling pool. The third step is 5-6m higher than the second stilling pool. The second stilling pool slopes upward with a height difference of 1-2m. The third scheme is tested under the above working conditions and the corresponding results are obtained, including whether the lateral flow velocity exceeds the specification value. The fourth plan changes the gentle slope of 1:15 to a steep slope of 1:4 based on the first plan, and the rest remains unchanged; Using the above working conditions, the fourth scheme is tested and corresponding results are obtained, including whether the lateral flow velocity exceeds the standard value; Compare the test results of the second, third and fourth options, and select the best result as the recommended option.

2. The method for optimizing navigation flow conditions of a tributary confluence section of a waterway according to claim 1, characterized in that: In step S1, the model adopts a normal fixed-bed river engineering model, which meets the similarity conditions of geometry, gravity, resistance and continuity.

3. The method for optimizing navigation flow conditions of a tributary confluence section of a waterway according to claim 2, characterized in that: In step S1, the river channel model is made of cement mortar using the section plate method, and the energy dissipation pool is made of rubber board and cement mortar.

4. The method for optimizing navigation flow conditions of a tributary confluence section of a waterway according to claim 3, characterized in that: In step S1, the model main stream is 2.5-3km long, the tributary is 1-1.5km long, the tributary converges into the main stream at an angle of 40°-60°, the main stream is arranged with 50-60 sections, the spacing is 42-60m, the tributary is arranged with 50-60 sections, the spacing is 17-30m, and 5-10 sections are arranged at the intersection of the main stream and the tributary, and the spacing is set according to the terrain characteristics.

5. The method for optimizing navigation flow conditions of a tributary confluence section of a waterway according to claim 4, characterized in that: In step S2, the radius of the arc-shaped retaining wall at the inlet of the first stilling pool is 15-20m, and the radius of the arc-shaped retaining wall at the outlet of the first stilling pool is 15-20m.

6. The method for optimizing navigation flow conditions of a tributary confluence section of a waterway according to claim 5, characterized in that: In step S2, the width of the first energy dissipation pool is 50-60m and the length is 70-80m; the first energy dissipation pool is 22m long, the bottom elevation is 36.5m, and the first step is 2m long; the second energy dissipation pool is 22m long, the bottom elevation is 33.5m, and the second step is 2m long; the third energy dissipation pool is 24m long, the bottom elevation is 30.5m, and the third step is 1m long.

7. The method for optimizing navigation flow conditions of a tributary confluence section of a waterway according to claim 6, characterized in that: In step S2, the bottom elevation of the second energy dissipation pool is 26.2 m, and the second energy dissipation pool is sloped upward to a top elevation of 27.7 m.

8. The method for optimizing navigation flow conditions of a tributary confluence section of a waterway according to claim 7, characterized in that: In step S2, one working condition is that the tributary flow is the most unfavorable to navigation conditions. The 20-year flood flow is selected for simulation and finally determined to be Q = 532m 3 / s, the main stream flow is selected according to the flood standard of once in five years, and finally determined to be Q = 340m 3 / s.

9. The method for optimizing navigation flow conditions of a tributary confluence section of a waterway according to claim 8, characterized in that: In step S3, the physical flow barrier of the second solution is a straight flow barrier with a length of 30-40m and a width of 1.5-2m, and the shortest distance between the flow barrier and the channel boundary is 6.5m; The third option sets a sedimentation tank length of 40-50m and a bottom elevation of 27.7m.

10. The method for optimizing navigation flow conditions of a tributary confluence section of a waterway according to any one of claims 1 to 9, characterized in that: In the test, the water level was measured with a probe; the surface velocity was measured with a surface particle imaging system, and the vertical velocity was measured with a propeller flow meter.

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