A method for optimizing navigable flow conditions of a branch of a waterway

Abstract

The application relates to the field of waterway engineering, in particular to a method for optimizing navigation flow conditions of a waterway branch stream confluence section. The method comprises the following steps: setting a corresponding physical model of the waterway branch stream confluence section, based on the physical model, carrying out engineering measures such as widening a branch stream mouth, setting left and right side slopes, setting a first step-type stilling basin, designing a stilling basin height difference and corresponding steps, testing whether a transverse flow rate exceeds a standard value under an adverse working condition, based on a test result, optimizing and modifying the physical model, through multiple sets of contrast tests, such as setting a solid separation dike, a sand trap, a 1:4 steep slope and the like, and selecting an optimal scheme as the optimization scheme of the navigation flow conditions of the waterway branch stream confluence section in comprehensive consideration of engineering technicality, economy, coordination between engineering measures and the environment and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of waterway engineering, and particularly relates to a method for optimizing navigation flow conditions of an inflow section of a waterway tributary. BACKGROUND

[0002] In a river system, the confluence area of the main stream and the tributary is the inflow section. This section of the river presents complex hydrodynamic characteristics due to the convergence of water flow. The inflow section not only carries the superposition of water flow from both sides, but also exchanges sediment, pollutants and heat, which has a significant impact on the local ecological environment and water quality. Especially, transverse flow velocity often appears at the inflow, which is perpendicular to the main flow direction and is distributed along the river width, resulting in complex vortex and turbulent flow phenomena near the confluence point.

[0003] The transverse flow velocity increases the complexity and risk of ship maneuvering, which may result in the river being unable to navigate. The transverse flow velocity may force the ship to deviate from the intended course, especially in curved or narrow sections of the waterway, increasing the risk of colliding with the shore or obstacles. In addition, unstable flow patterns also affect the stability and safety of ships, especially in adverse weather conditions.

[0004] Therefore, engineering measures are needed to optimize the flow conditions of the inflow section to meet the navigation requirements of the river. SUMMARY

[0005] The present application aims to solve the problem that the existing technology has transverse flow velocity in the inflow section of the main stream and tributary, which increases the complexity and risk of ship maneuvering, resulting in the river being unable to navigate, and engineering measures are needed to optimize the flow conditions of the inflow section to meet the navigation requirements of the river, by providing a method for optimizing navigation flow conditions of an inflow section of a waterway tributary.

[0006] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0007] A method for optimizing navigation flow conditions of an inflow section of a waterway tributary, comprising the following steps:

[0008] S1, constructing a physical model of the inflow section of the waterway tributary;

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

[0010] The branch stream mouth is widened, and is excavated to a bottom elevation, left and right side slopes are provided, and the slope ratio is 1:2; a first stilling basin is arranged at the dry branch stream intersection, the first stilling basin is a stepped stilling basin, arc-shaped retaining walls are arranged on both sides of the first stilling basin inlet and on both sides of the first stilling basin outlet, and a horn mouth is formed; the first stilling basin comprises a first-stage, a second-stage and a third-stage, the first-stage stilling basin is 3-4 m higher than the second-stage stilling basin, and the second-stage stilling basin is 3-4 m higher than the third-stage stilling basin; a step is arranged at the tail of each stilling basin, and the step is 1-2 m higher than the corresponding stilling basin; the first stilling basin outlet is downwardly sloped at a ratio of 1:15, the slope bottom connects a second stilling basin, the third-stage step is 5-6 m higher than the second stilling basin, and the second stilling basin is upwardly sloped, and the height difference is 1-2 m;

[0011] At least one working condition is set, the first scheme is tested, and corresponding results are obtained, the results including whether the transverse flow velocity exceeds the specification value;

[0012] S3, based on the test results of the first scheme, if the transverse flow velocity exceeds the specification value, a navigation flow condition optimization test is performed on the physical model, a second scheme, a third scheme and a fourth scheme are set;

[0013] The second scheme increases an entity separation dike on the basis of the first scheme, and the entity separation dike is arranged at the throat of the dry branch stream intersection; the foregoing working condition is adopted, the second scheme is tested, and corresponding results are obtained, the results including whether the transverse flow velocity exceeds the specification value;

[0014] The third scheme excavates a sand sink at the third-stage stilling basin outlet on the basis of the first scheme, the third-stage stilling basin is 2-3 m higher than the sand sink, a step is arranged at the tail of the sand sink, and the sand sink is downwardly sloped at a ratio of 1:15, the slope bottom connects the second stilling basin, the third-stage step is 5-6 m higher than the second stilling basin, and the second stilling basin is upwardly sloped, and the height difference is 1-2 m; the foregoing working condition is adopted, the third scheme is tested, and corresponding results are obtained, the results including whether the transverse flow velocity exceeds the specification value;

[0015] The fourth scheme changes the gentle slope of 1:15 to an abrupt slope of 1:4 on the basis of the first scheme, and the rest remains unchanged; the foregoing working condition is adopted, the fourth scheme is tested, and corresponding results are obtained, the results including whether the transverse flow velocity exceeds the specification value;

[0016] The test results of the second scheme, the third scheme and the fourth scheme are compared and selected, and the optimal result is selected as a recommended scheme.

[0017] The method for optimizing the navigation flow condition of a branch channel confluence section of the application comprises the following steps: S1, a physical model corresponding to the branch channel confluence section is set up; S2, the physical model is modified based on the test results; S3, the optimal scheme is selected from the schemes obtained in step S2, and the optimal scheme is used as the navigation flow condition optimization scheme of the branch channel confluence section.

[0018] As a preferred technical scheme of the application, in step S1, the model adopts a normal fixed-bed river model, and satisfies geometric, gravity, resistance and continuous similarity conditions.

[0019] As a further preferred technical scheme of the application, in step S1, the river model is made of cement mortar by using the cross-section plate method, and the stilling basin is made of gum plate and cement mortar.

[0020] As a further preferred technical scheme of the application, in step S1, the length of the model main stream is 2.5-3 km, the length of the branch stream is 1-1.5 km, the confluence angle of the branch stream into the main stream is 40°-60°, the number of cross sections of the main stream is 50-60, the interval is 42-60 m, the number of cross sections of the branch stream is 50-60, the interval is 17-30 m, and the number of cross sections at the intersection of the main stream and the branch stream is 5-10, and the interval is set according to the topographic features.

[0021] As a further preferred technical scheme of the application, in step S2, the radius of the circular arc type retaining wall at the inlet of the first stilling basin is 15-20 m, and the radius of the circular arc type retaining wall at the outlet of the first stilling basin is 15-20 m.

[0022] As a further preferred technical scheme of the application, in step S2, the width of the first stilling basin is 50-60 m, and the length is 70-80 m; the length of the first stage is 2 m, and the bottom elevation is 36.5 m; the length of the second stage is 2 m, and the bottom elevation is 33.5 m; the length of the third stage is 1 m, and the bottom elevation is 30.5 m.

[0023] As a further preferred technical scheme of the application, in step S2, the bottom elevation of the second stilling basin is 26.2 m, and the upward slope of the second stilling basin is to the top elevation of 27.7 m.

[0024] As a further preferred technical scheme of the application, in step S2, one working condition is that the branch stream flow is from the most unfavorable angle for navigation condition, and the 20-year flood flow is selected for simulation, and finally determined as Q=532 m 3 / s, the dry flow is selected according to the 5-year flood standard, and finally determined as Q=340m 3 / s.

[0025] As a further preferred technical solution of the present application, in step S3, the entity cutoff dike of the second solution is a straight cutoff dike, with a length of 30-40m and a width of 1.5-2m, and the shortest distance between the cutoff dike and the boundary of the channel is 6.5m.

[0026] The length of the sand trap set in the third solution is 40-50m, and the bottom elevation is 27.7m.

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

[0028] As described above, due to the adoption of the above technical solutions, the present application has the following beneficial effects:

[0029] The navigation flow condition optimization method for the branch channel confluence section of the present application, by setting the corresponding physical model of the branch channel confluence section, based on the physical model, widening the branch outlet, setting left and right side slopes, setting a stepped first stilling basin, designing the height difference of the stilling basin and the corresponding steps, etc. Engineering measures, whether the transverse flow velocity exceeds the standard value is tested under adverse conditions, based on the test results, the physical model is optimized and modified, through multiple comparison tests, such as setting an entity cutoff dike, a sand trap, a 1:4 steep slope, etc. From the comprehensive consideration of engineering technology, economy and coordination between engineering measures and environment, the optimal solution is selected as the navigation flow condition optimization scheme for the branch channel confluence section. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 It is a schematic diagram of the plane layout of the first solution;

[0031] Figure 2 It is a longitudinal section view of the stilling basin of the first solution;

[0032] Figure 3 It is a transverse flow velocity contour map of working condition 1 of the first solution;

[0033] Figure 4 It is a transverse flow velocity contour map of working condition 2 of the first solution;

[0034] Figure 5 It is a schematic diagram of the plane layout of the second solution;

[0035] Figure 6 It is a transverse flow velocity contour map of working condition 1 of the second solution;

[0036] Figure 7 It is a schematic diagram of the plane layout of the third solution;

[0037] Figure 8 Fig. 9 is a longitudinal section view of the stilling basin according to the third embodiment;

[0038] Figure 9 Fig. 10 is a transverse velocity contour map of the working condition 1 according to the third embodiment;

[0039] Figure 10 Fig. 11 is a schematic plan view of the fourth embodiment;

[0040] Figure 11 Fig. 12 is a longitudinal section view of the stilling basin according to the fourth embodiment;

[0041] Figure 12 Fig. 13 is a transverse velocity contour map of the working condition 1 according to the fourth embodiment. DETAILED DESCRIPTION

[0042] The present application will be further described in conjunction with test examples and specific embodiments. However, it should not be understood that the scope of the above-mentioned subject matter of the present application is limited to the following examples, and any technology realized based on the content of the present application falls within the scope of the present application.

[0043] In the description of the specific embodiments of the present application, the orientation or positional relationship expression terms appearing without special indication, such as "upper", "lower", "left", "right", "center", "inner", "outer", etc., are based on the orientation or positional relationship expression shown in the drawings, or the orientation or positional relationship in which the product / equipment / device of the present application is usually placed. These orientation or positional relationship terms are merely for the convenience of describing the present application or simplifying the description in the specific embodiments, for the purpose of facilitating the quick understanding of the scheme by the skilled person, and therefore cannot be understood as indicating or implying that a specific device / component / element must have a specific orientation, or must be constructed and operated in a specific positional relationship, and thus cannot be understood as limiting the present application.

[0044] In addition, if the terms "horizontal", "vertical", "suspended", "parallel", etc. appear, it does not mean that the corresponding device / component / element must be absolutely horizontal or vertical or suspended or parallel, but can be slightly inclined or deviated. For example, "horizontal" only means that its direction is relatively more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly inclined. Alternatively, it can be simplified to mean that the corresponding device / component / element is arranged in the direction of "horizontal", "vertical", "suspended", "parallel", etc., and can have an error / deviation of ±10% with respect to the corresponding direction, more preferably an error / deviation of ±8% or less, more preferably an error / deviation of ±6% or less, more preferably an error / deviation of ±5% or less, and more preferably an error / deviation of ±4% or less. 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 application.

[0045] In addition, the terms appearing in the description of the embodiments of the present application, such as "first", "second", "third", etc., are only used to distinguish the same or similar components for description, and should not be understood as emphasizing or implying the relative importance of the specific components.

[0046] In addition, in the description of the embodiments of the present application, "several", "a plurality of", "several" represent at least 2. It can be 2, 3, 4, 5, 6, 7, 8, 9, etc. Any case, it can even be more than 9 cases.

[0047] In addition, in the description of the technical solutions of the present application, unless otherwise specified / limited / limited, the terms "set", "install", "connect", "connect", "set", "lay", "arrange" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected, which can be welding, riveting, bolting, screwing, etc. The connection means commonly used in the art. Such connection can be mechanical connection, or electrical connection or communication connection, can be directly connected, or indirectly connected through an intermediate medium, can be the communication between two elements.

[0048] In the related art, the dry branch flow into the confluence section usually has a transverse flow velocity, which increases the complexity and risk of ship operation, causing the river to be unable to navigate, and requiring engineering measures to optimize the flow conditions of the confluence section to meet the navigation requirements of the river. For this reason, the technical solutions of the present application are described below in conjunction with Figures 1 to 12 .

[0049] Embodiment 1

[0050] The navigation flow condition optimization method for the branch flow into the confluence section of the waterway according to the present application comprises the following steps:

[0051] Step 1, build a physical model of the branch flow into the confluence section of the waterway.

[0052] 1, model design

[0053] The model adopts a normal fixed bed river model with a plane scale λ L = 50, a vertical scale λ H = 50. According to the basic similarity criteria of the river model flow, the geometric, gravity, resistance and continuity similarity conditions need to be met, from which the following similarity scales can be obtained:

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

[0055] Flow velocity scale:

[0056] Flow time scale:

[0057] Flow scale:

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

[0059] Based on experimental data, the tributary flow velocity during low water levels is 0.6–1.5 m / s, and the minimum water depth is approximately 2 m. Therefore, the minimum Reynolds number for the model is Re. M =1200; Based on this estimation, the model flow during the flood season meets the requirements for entering the turbulent state (Reynolds number > 1000). The hydrological combination in this embodiment is the flood condition of a 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 was constructed using the cross-section method with cement mortar. Based on topographical features and importance, the tributary cross-sections were spaced approximately 0.3m apart, the main stream cross-sections approximately 1m apart, and the cross-sections at the confluence of main and tributary sections approximately 0.36m apart. The traverse was laid out using a total station and checked with a theodolite and steel tape, ensuring the trigonometric closure error for horizontal control was less than ±5". The errors in drawing the cross-section planes and elevations were both less than 0.5mm, with installation errors controlled within ±1.0cm for the plane and within ±0.5mm for the elevation. Furthermore, localized cross-sections and intersecting cross-sections were used to meticulously sculpt complex terrain features such as protruding promontory, boulders, reefs, stone ridges, and deep pools to ensure geometric similarity of the model.

[0062] The study section of the river contains water-related structures such as stilling basins. The model was made of plywood, cement mortar, etc., and was made strictly according to geometric similarity on the plane. The small deviation in surface roughness has a negligible impact on the test results.

[0063] The flow control system mainly consists of a water storage tank, water pump, motor, electromagnetic flow meter, computer and other control software, and the maximum flow rate can be 300L / s.

[0064] Water levels are measured using a probe with an accuracy of 0.1 mm. One water gauge is placed at each water gauge section of the tributaries, and at least three water gauges are placed at each water gauge section of the main stream (left, center, and right) to accurately control and read water levels and to understand the gradient of the banks and the river center. The spacing between water gauges is 250–400 m, with an average spacing of approximately 350 m (7.0 m on the model).

[0065] Flow velocity is primarily measured using a surface particle imaging system, which can quickly, accurately, and comprehensively measure the surface flow field. Vertical flow velocity is primarily measured using a propeller velocity meter.

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

[0067] 3. Model range

[0068] The dry stream of the model is 2.5-3 km long, the tributary is 1-1.5 km long, and the tributary enters the dry stream at an angle of 40°-60°. In this embodiment, the tributary can be about 1.1 km long, the dry stream can be about 2.6 km long, the dry stream part can be about 1.4 km below the tributary inlet, the tributary inlet can be about 1.2 km above, and the tributary can enter the dry stream at an angle of about 45°. The model range can ensure reasonable distribution of the flow entering the model. The inlet has sufficient length and bending section to allow the water flow entering the test section at each stage to be fully adjusted. The outlet is relatively straight to ensure the similarity of the tail water flow pattern of the model.

[0069] The model dry stream is arranged with 50-60 sections (marked as DM), with a spacing of 42-60 m, the tributary is arranged with 50-60 sections (marked as HCS), with a spacing of 17-30 m, and the dry and tributary junction is arranged with 5-10 sections, with a spacing set according to the topographic features. In this embodiment, a total of 113 sections are arranged in the model, including 56 sections arranged in the tributary with a section spacing of 15 m, 51 sections arranged in the dry stream with a section spacing of 50 m (the dry stream section spacing is encrypted at the dry and tributary junction and the bending section), and 6 sections arranged at the dry and tributary junction with a section spacing set according to the topographic features, with an average spacing of about 15 m.

[0070] Step two, conduct navigation water flow condition test based on physical model.

[0071] 1. First scheme arrangement

[0072] (1) Tributary section

[0073] The tributary inlet is widened, and the section from HCS1 to HCS3 is excavated to the bottom elevation of 38.5 m; the left and right side slopes have an elevation of 43 m, and the slope ratio is 1:2.

[0074] (2) Design of first stilling basin at dry and tributary junction

[0075] The junction connecting sections are HCS3-HCS19.

[0076] The two sides of the first stilling basin inlet are connected by a circular arc type retaining wall with a radius of 15-20 m from the cross section HCS2 to HCS5, and the height of the retaining wall is 43 m in the embodiment, wherein the height of the retaining wall between the cross sections HCS4 to HCS6 is 40 m; the two sides of the first stilling basin outlet are connected by a circular arc type retaining wall with a radius of 15-20 m from the cross section HCS14 to HCS15, and the height of the retaining wall is 43 m in the embodiment, and a horn mouth is formed.

[0077] The width of the first stilling basin is 50-60 m, and the length is 70-80 m, and the width of the first stilling basin is 54.4 m and the total length is 73 m in the embodiment. The first stilling basin comprises a first stage, a second stage and a third stage, the first stage is 3-4 m higher than the second stage, and the second stage is 3-4 m higher than the third stage, and a step is arranged at the tail of each stage, and the step is 1-2 m higher than the corresponding stage; in the embodiment, the first stage is from the cross section HCS6 to HCS7, the length is 22 m, and the bottom height is 36.5 m, and the first stage step is 2 m long; the second stage is from the cross section HCS9 to HCS10, the length is 22 m, the bottom height is 33.5 m, and the second stage step is 2 m long; the third stage is from the cross section HCS12 to HCS13, the length is 24 m, the bottom height is 30.5 m, and the third stage step is 1 m long.

[0078] The first stilling basin outlet is downwardly sloped at a slope of 1:15 from HCS14 to HCS16, and the third stage is 5-6 m higher than the second stage, and the bottom height is 26.2 m in the embodiment, and the second stilling basin is from the cross section HCS16 to HCS17 with a bottom height of 26.2 m; the second stilling basin is upwardly sloped, and the height difference is 1-2 m, and the slope top height is 27.7 m from the cross section HCS17 to HCS18 in the embodiment, as shown in Figure 1 and Figure 2 .

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

[0080] Working condition 1: The branch flow is selected from the most unfavorable angle for navigation condition, and the 20-year flood flow is selected for simulation, and finally determined as Q=532 m 3 / s, the dry flow is selected according to the 5-year flood standard, and finally determined as Q=340 m 3 / s, and the tail water level is determined by interpolation according to the corresponding stake number of the dry flow 5-year flood level, and finally determined as 35.32 m.

[0081] Working condition 2: The branch flow is selected as the 5-year flood flow, Q=297 m 3 / s, the dry flow is Q=0 m 3 / s, and the final tail water level is 34 m.

[0082] The flow velocity was measured by the XKVMS series surface flow field measurement system developed by the Southwest Water Conservancy and Hydropower Engineering Scientific Research Institute, and the water level was observed by the water level measuring needle. The surface flow velocity distribution, flow pattern and water surface fluctuation in the confluence area were observed.

[0083] (1) The experimental results of working condition 1 show that the confluence degree in the channel of the confluence area is closer to the left boundary of the channel, but it is still small as a whole. This is because the stilling basin processes the water flow, and the angle between the center line of the channel and the direction of the branch flow is also small, and there is no complex water flow condition in the channel.

[0084] The stilling basin processes the branch water, but in the first scheme, the transverse flow velocity is large. The maximum transverse flow velocity in the channel range is 0.49 m / s, which is located in the left area of the section DM34 channel, and there is an area with excessive flow velocity in the left side of the sections DM30-DM32, which is an ellipse with a transverse dimension of 38.15 m and a longitudinal dimension of about 29.1 m. In the channel of the sections DM33-DM35, the area with excessive flow velocity almost occupies the entire channel, with a transverse dimension of 57.26 m and a longitudinal dimension of about 47.12 m. In summary, the transverse flow velocity distribution does not meet the specification requirements. Details are shown in Figure 3 .

[0085] (2) The experimental results of working condition 2 show that since there is no flow in the main stream under this working condition, when the branch flow enters the main stream, there will be partial backflow at the section DM25-DM30, but after the energy dissipation effect of the stilling basin, the backflow velocity is small, with a maximum value of 0.27 m / s. The flow velocity in the channel of the confluence area is within 2 m / s, the rest of the flow pattern is good, and the angle between the center line of the channel and the direction of the branch flow is also small.

[0086] After the energy dissipation effect of the stilling basin, the transverse flow velocity in the channel range exceeds the specification value, with a maximum value of 0.35 m / s, which is located on the left side of the boundary line of the section DM29. The transverse dimension of the area exceeding the specification value is 21.07 m, and the longitudinal dimension is 22.18 m. The transverse flow velocity distribution basically meets the specification requirements. Details are shown in Figure 4 .

[0087] Flow pattern and water surface fluctuation in the confluence entrance river section, in order to further observe the flow pattern and water surface fluctuation in the confluence entrance river section, the sections DM25 and DM29 downstream of the confluence area with larger water level fluctuation were selected to set observation points. The water level fluctuation difference of the section DM25 in the confluence area is about 33 cm, and the water level fluctuation difference of the section DM29 is about 31.3 cm. The flow pattern in the channel is good and stable.

[0088] Compared with the working condition 1, the working condition 2 sets the observation point at the same section, wherein the water level fluctuation difference at the section DM25 is about 17.89 cm, the water level fluctuation difference at the section DM29 is 33.54 cm, and the water flow in the channel is good and stable.

[0089] 3. The first scheme converges into the river section and the channel flow velocity statistics table

[0090] Table 1 statistics the channel flow velocity of the working condition 1 of the first scheme from the section DM26 to DM36, wherein the maximum resultant velocity is 1.79 m / s, which appears at the section DM35; the minimum value is 0.16 m / s, which appears at the section DM28, the maximum transverse flow velocity value is 0.49 m / s, which appears at the section DM34 (converging area), and the minimum transverse flow velocity value is 0.01 m / s, which appears at the section DM26.

[0091] Table 1 channel flow velocity statistics table (m / s) of the first scheme working condition 1 of the branch stream into the channel confluence section

[0092]

[0093]

[0094]

[0095] Table 2 statistics the channel flow velocity of the working condition 2 of the first scheme from the section DM26 to DM36, wherein the maximum resultant velocity is 1.11 m / s, which appears at the section DM31; the minimum value is 0.03 m / s, which appears at the section DM30, the maximum transverse flow velocity value is 0.28 m / s, which appears at the section DM29 (converging area), and the minimum transverse flow velocity value is 0.0 m / s, which appears at the section DM26.

[0096] Table 2 channel flow velocity statistics table (m / s) of the first scheme working condition 2 of the branch stream into the channel confluence section

[0097]

[0098]

[0099]

[0100] 4. Analysis of test results

[0101] The first scheme adopts the way of stilling basin to process the branch stream, but due to the typical mountain river terrain features of the branch stream, the water flow speed is fast, and under the condition of large upstream water flow, the transverse flow velocity of the converging area is larger than the range of the specification value, and the first scheme needs to be further modified.

[0102] Step three, the navigation water flow condition optimization test is carried out on the physical model.

[0103] 1. The first scheme arrangement

[0104] On the basis of the first scheme, an entity dike is added to reduce the transverse velocity of the confluence area. The length of the straight dike is 30-40 m, the width is 1.5-2 m, and in the embodiment, the length is 37.4 m, the width is 2 m, and the top elevation is 27.7 m. The shortest distance between the dike and the channel boundary is about 6.5 m. The plan layout is shown in Figure 5 .

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

[0106] Condition 1: Same as the first scheme condition 1.

[0107] (1) Under the action of the entity dike, the resultant velocity of the water flow in the channel is generally small, and the flow velocity in the confluence area is within 2 m / s. The angle between the channel center line and the branch flow direction is relatively small, and there is no complex water flow pattern in the channel.

[0108] (2) Although the overflow dam processes the water flow, the transverse flow velocity is still large under this scheme. The maximum transverse flow velocity measured in the channel range is 0.44 m / s, which is located in the right area of the channel at section DM35. There is an area with flow velocity exceeding the standard in the center of the channel at section DM35, with a transverse dimension of about 51.22 m and a longitudinal dimension of about 47.1 m. The transverse flow velocity distribution does not meet the specification requirements. Details are shown in Figure 6 .

[0109] 3. Second scheme confluence entrance river section channel flow velocity statistics

[0110] Table 3 summarizes the channel flow velocity of section DM26 to DM36 in condition 1 of the second scheme, in which the maximum resultant velocity is 1.97 m / s, which occurs at section DM34; the minimum value is 0.24 m / s, which occurs at section DM26; the maximum transverse flow velocity value is 0.44 m / s, which occurs at section DM35; and the minimum transverse flow velocity value is 0.0 m / s, which occurs at sections DM27 and DM29.

[0111] Table 3 Channel flow velocity statistics of the second scheme condition 1 in the channel branch confluence section (m / s)

[0112]

[0113]

[0114]

[0115] 4. Analysis of test results

[0116] Compared with the first scheme, the second scheme does not produce all-round improvement in the navigation channel conditions of the confluence reach after the physical separation dike is replaced. The distribution of the transverse flow velocity does not meet the requirements of the specification, so the ship route will be hindered to a certain extent under the second scheme.

[0117] Step four, optimization test of navigation flow conditions for the physical model.

[0118] 1. Third scheme arrangement

[0119] The third scheme cancels the physical separation dike, excavates a sand pool with a bottom elevation of 27.7 m and a length of 40-50 m at the outlet of the third-stage stilling basin of the second scheme, and slopes from the tail of the sand pool (elevation of 28.7 m) at 1:15, with the slope bottom elevation being 26.2 m. In this embodiment, a sand pool with a length of 50 m can be selected. From the section HCS16 to HCS17 is the second stilling basin with a bottom elevation of 26.2 m, and slopes from the section HCS17 to HCS18, with the slope top elevation being 27.7 m. The plan arrangement is shown in Figure 7 , and the longitudinal section of the stilling basin is shown in Figure 8 .

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

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

[0122] (1) Under the action of the stilling basin and the sand pool, the combined flow velocity in the channel is larger than that of the second scheme, and the angle between the channel center line and the branch flow direction is also larger, and the flow pattern in the channel is more chaotic.

[0123] (2) Due to the energy dissipation effect of the stilling basin on the flow, the transverse flow velocity in the confluence area channel is more obviously improved. There is no area in the confluence area channel that exceeds the specification value, and the maximum value is 0.24 m / s, which is located at the left side of the channel at section DM34. In summary, the ship can safely navigate. Details are shown in Figure 9 .

[0124] 3. Third scheme confluence reach channel flow velocity statistical table

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

[0126] Table 4: Flow velocity statistics of the third scheme of the approach channel in the confluence section under working condition 1 (m / s)

[0127]

[0128]

[0129]

[0130] 4. Analysis of test results

[0131] Compared with the second scheme, the flow conditions in the intersection area of the third scheme have been significantly improved, and the distribution of the transverse velocity meets the requirements of the specification. This scheme is basically qualified.

[0132] Step five: Optimization test of navigation flow conditions for the physical model.

[0133] 1. Layout of the fourth scheme

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

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

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

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

[0138] (2) After setting a 1:4 steep slope, the transverse velocity has been greatly improved, and there is no area in the approach channel that exceeds the range value, which can be safely navigated. Details are shown in Figure 12 .

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

[0140] 3. Flow velocity statistics of the fourth scheme confluence section

[0141] Table 6 statistics of the fourth scheme working condition 1 cross section DM26 to DM36 channel flow velocity, wherein the maximum combined velocity is 1.58 m / s, which appears at the cross section DM36, and the minimum value is 0.23 m / s, which appears at the cross section DM34. The maximum lateral flow velocity value is 0.29 m / s, which appears at the cross section DM35, and the minimum lateral flow velocity value is 0.00 m / s, which appears at the cross section DM28, DM30 to DM31 and DM33 to DM34 and the cross section DM36.

[0142] Table 6 statistics of the fourth scheme working condition 1 cross section DM26 to DM36 channel flow velocity, wherein the maximum combined velocity is 1.58 m / s, which appears at the cross section DM36, and the minimum value is 0.23 m / s, which appears at the cross section DM34. The maximum lateral flow velocity value is 0.29 m / s, which appears at the cross section DM35, and the minimum lateral flow velocity value is 0.00 m / s, which appears at the cross section DM28, DM30 to DM31 and DM33 to DM34 and the cross section DM36.

[0143]

[0144]

[0145]

[0146] 4、Test results analysis

[0147] In the case of taking 1:4 steep slope and stilling basin, the river direction is optimized, the distance from the tail of the first stilling basin to the intersection area is increased, the flow energy of the confluence into the main stream is weakened to a certain extent, the lateral flow velocity of working condition 1 is obviously improved, the lateral flow velocity reaches the navigation standard and the flow state is good, so the fourth scheme can be recommended.

[0148] The navigation flow condition optimization method of the branch stream into the confluence section in the embodiment sets the corresponding physical model of the branch stream into the confluence section, performs widening of the branch stream mouth, left and right side slope setting, setting of the first stilling basin, design of the height difference of the stilling basin and corresponding step design and other engineering measures, tests whether the lateral flow velocity exceeds the standard value under the adverse working condition, optimizes and modifies the physical model based on the test results, selects the optimal scheme as the navigation flow condition optimization scheme of the branch stream into the confluence section through a plurality of comparison tests, such as setting of the entity separation dike, sand trap, 1:4 steep slope and the like, and comprehensively considers the engineering technicality, economy and coordination of the engineering measures and the environment.

[0149] The above merely describes preferred embodiments of the present application and is not intended to limit the present application, and any modification, equivalent replacement and improvement within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for optimizing navigable flow conditions in a reach of a waterway branch that flows into a junction, characterized in that, The method comprises the following steps: S1, constructing a physical model of a branch channel confluence section; S2, performing a navigation flow condition test based on the physical model, and setting a first scheme; The branch channel mouth is widened and excavated to the bottom elevation, and left and right side slopes are arranged with a slope ratio of 1:2; a first stilling basin is arranged at the junction of the main channel and the branch channel, the first stilling basin is a stepped stilling basin, arc-shaped retaining walls are arranged on both sides of the inlet and outlet of the first stilling basin, and a horn mouth is formed; the first stilling basin comprises a first-stage stilling basin, a second-stage stilling basin and a third-stage stilling basin, the first-stage stilling basin is 3-4 m higher than the second-stage stilling basin, and the second-stage stilling basin is 3-4 m higher than the third-stage stilling basin; a step is arranged at the tail of each stilling basin, and the step is 1-2 m higher than the corresponding stilling basin; the outlet of the first stilling basin is downwardly sloped at a ratio of 1:15, the slope bottom connects a second stilling basin, the third-stage step is 5-6 m higher than the second stilling basin, and the second stilling basin is upwardly sloped with a height difference of 1-2 m; At least one working condition is set, the first scheme is tested, and corresponding results are obtained, the results including whether the transverse flow rate exceeds a standard value; S3, based on the test results of the first scheme, if the transverse flow rate exceeds the standard value, performing a navigation flow condition optimization test on the physical model, and setting a second scheme, a third scheme and a fourth scheme; The second scheme adds a solid dike on the basis of the first scheme, the solid dike is arranged at the throat of the junction of the main channel and the branch channel; the second scheme is tested by using the working condition, and corresponding results are obtained, the results including whether the transverse flow rate exceeds the standard value; The third scheme excavates a sand sink at the outlet of the third-stage stilling basin on the basis of the first scheme, the third-stage stilling basin is 2-3 m higher than the sand sink, a step is arranged at the tail of the sand sink, the step is downwardly sloped at a ratio of 1:15, the slope bottom connects the second stilling basin, the third step is 5-6 m higher than the second stilling basin, and the second stilling basin is upwardly sloped with a height difference of 1-2 m; the third scheme is tested by using the working condition, and corresponding results are obtained, the results including whether the transverse flow rate exceeds the standard value; The fourth scheme changes the gentle slope of 1:15 to an abrupt slope of 1:4, and the rest remains unchanged; The fourth scheme is tested by using the working condition, and corresponding results are obtained, the results including whether the transverse flow rate exceeds the standard value; The test results of the second scheme, the third scheme and the fourth scheme are compared and selected, and the optimal result is selected as a recommended scheme.

2. The method according to claim 1, wherein, In step S1, the model adopts a normal fixed-bed river model, and satisfies geometric, gravity, resistance and continuous similarity conditions.

3. The method according to claim 2, wherein, In step S1, the river model is made of cement mortar by using the section plate method, and the stilling basin is made of gum plate and cement mortar.

4. The method according to claim 3, wherein, In step S1, the model main channel is 2.5-3 km long, the branch channel is 1-1.5 km long, the branch channel confluence angle is 40°-60°, 50-60 sections are arranged in the main channel with a spacing of 42-60 m, 50-60 sections are arranged in the branch channel with a spacing of 17-30 m, and 5-10 sections are arranged at the junction of the main channel and the branch channel with a spacing set according to the terrain characteristics.

5. The method for optimizing navigable flow conditions of a branch 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 basin is 15-20 m, and the radius of the arc-shaped retaining wall at the outlet of the first stilling basin is 15-20 m.

6. The method for optimizing navigable flow conditions of a branch confluence section of a waterway according to claim 5, characterized in that, In step S2, the first stilling basin has a width of 50-60 m and a length of 70-80 m; the first-stage stilling basin has a length of 22 m, a bottom elevation of 36.5 m, and a first-stage step of 2 m; the second-stage stilling basin has a length of 22 m, a bottom elevation of 33.5 m, and a second-stage step of 2 m; and the third-stage stilling basin has a length of 24 m, a bottom elevation of 30.5 m, and a third-stage step of 1 m.

7. The method according to claim 6, wherein, In step S2, the second stilling basin has a bottom elevation of 26.2 m, and is upwardly sloped to a slope top elevation of 27.7 m.

8. The method according to claim 7, wherein, In step S2, one working condition is that the branch flow is from the most unfavorable angle for navigation condition, and the 20-year flood flow is selected for simulation, and finally determined as Q = 532 m 3 / s, and the main flow is selected according to the 5-year flood standard, and finally determined as Q = 340 m 3 / s.

9. The method according to claim 8, wherein, In step S3, the solid partition dike of the second scheme is a straight partition dike, has a length of 30-40 m and a width of 1.5-2 m, and has a shortest distance of 6.5 m from the boundary of the channel. The sand trap set in the third scheme has a length of 40-50 m and a bottom elevation of 27.7 m.

10. The method for optimizing navigable flow conditions of a branch confluence section of a waterway according to any one of claims 1 to 9, characterized in that, In the test, the water level is measured by a measuring needle; the surface flow velocity is measured by a surface particle imaging system, and the vertical flow velocity is measured by a propeller flowmeter.

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