Low-water flow measuring groove structure

Abstract

The utility model relates to the technical field of hydrology and water resource monitoring, in particular to a low-water flow measuring groove structure which comprises a rectangular groove, a trapezoidal groove and a compound combined groove. The low-water flow measuring groove structure comprises a bottom plate, a wing wall, a tooth wall, an energy dissipation body, a depth measuring gauge and an operation platform, the bottom plate is located at the bottom of the low-water flow measuring groove, the wing wall is located above the bottom plate and connected with the bottom plate, the tooth wall is embedded under a riverbed, the top of the tooth wall is connected with the bottom plate, and the energy dissipation body and the bottom plate are poured together; according to the utility model, firstly, the low-water flow measuring groove is effectively designed and controlled, so that the construction position and the gradient selection of the flow measuring groove are more reasonable, the heights of the wing wall and the water inlet are more properly controlled, and the flow measuring groove can better meet the actual requirements of flow monitoring; and secondly, the design scheme is comprehensively considered, so that the appearance design of the flow measuring groove is more appropriate, the existing technical problems of vacuum negative pressure damage, submerging along a river, scouring and the like are further avoided, and the practical application effect of the low-water flow measuring groove is improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to hydrology water resource monitoring technical field, especially a low water measuring flume structure. BACKGROUND

[0002] With the continuous advancement of China's ecological civilization construction strategy, hydrology has expanded from meeting the demand of flood control and drought resistance to serving various fields of economic society. Realizing full-element, full-range and full-automatic monitoring of hydrology, serving and supporting water resource management, and assisting green development have become the current urgent and important tasks of hydrology. However, some river channels change frequently due to various factors such as frequent erosion and deposition, dispersed water flow, bifurcated river channel, chaotic flow direction and poor low water control conditions, which leads to difficult hydrological flow monitoring, complex and changeable water level-flow relationship, long-term influence on the quality and precision of test data and ecological flow monitoring, and restricts the high-quality development of hydrology. Through the construction and use of the low water measuring flume, the problem of low water flow monitoring is solved, the precision of flow monitoring is improved, the water level-flow relationship is single-valued, and an effective way for accurate monitoring of ecological flow is provided.

[0003] The low water measuring flume is generally built downstream of the basic section or the flow section of the hydrological station, and the distance from the basic section or the flow section should fully consider the operation needs of the flow monitoring facilities and equipment such as flow cableway or ADCP, and generally should be in the same direction as the water flow, can be located at the central position, or can be appropriately close to the shore to facilitate flow measurement and avoid erosion of the downstream shore.

[0004] The low water measuring flume in the prior art lacks effective design control, and the construction position and slope selection of part of the measuring flume are unreasonable, the height control of the wing wall and the water inlet is improper, which causes part of the measuring flume to not fully meet the actual needs of flow monitoring. Due to incomplete design scheme, improper design of part of the measuring flume leads to vacuum negative pressure damage, river submergence, erosion and the like, which affects the actual application of the low water measuring flume, and there are problems such as low use efficiency and easy damage due to non-standard design. UTILITY MODEL CONTENTS

[0005] In view of the problems such as low use efficiency and easy damage due to non-standard design that the distance of the low water measuring flume basic section or flow section should fully consider the operation needs of the flow monitoring facilities and equipment, facilitate flow measurement, and avoid erosion of the downstream shore, the utility model aims to provide a low water measuring flume structure to solve the problems in the prior art.

[0006] The utility model discloses a low water measuring flume's shape, low water measuring flume is composed of the water inlet gradual change section from upstream to downstream, stable measuring section and water outlet energy dissipation section three sections. The shape includes rectangular groove, trapezoidal groove and complex combination type groove, the rectangular groove is set to the measuring flume of the cross section shape of rectangle in stable measuring section, the trapezoidal groove is set to the measuring flume of the cross section shape of trapezoid in stable measuring section, the complex combination groove is set to the measuring flume of the cross section shape of two or more shapes combination in stable measuring section.

[0007] A low water measuring flume structure, including bottom plate, wing wall, tooth wall, energy dissipation body, depth gauge and operation platform, the bottom plate is located at low water measuring flume bottom, for carrying water flow, the wing wall is located above bottom plate and is connected with bottom plate, from upstream to downstream by water inlet gradual change section, stable measuring section and water outlet energy dissipation section three parts, whole pours, the tooth wall is embedded below riverbed, builds along the low water measuring flume periphery, top is connected with the bottom plate, the energy dissipation body is poured together with bottom plate, the depth gauge is set to stable measuring section flow monitoring section, the operation platform is located on the bottom plate outside monitoring section.

[0008] Further, the plane type of the wing wall water inlet gradual change section is set to "inverted eight character" type or "one character" type, adopts circular arc and stable measuring section connection, circular arc angle θ "one character" type is 90 DEG, "inverted eight character" type is generally less than 90 DEG.The wing wall stable measuring section upstream is connected with the wing wall of water inlet gradual change section, and the height is slightly lower than the height of the wing wall of water inlet gradual change section according to gradient, the wing wall stable measuring section downstream is connected with the wing wall of water outlet energy dissipation section, the wing wall stable measuring section left and right bank wing wall is arranged along the flow direction, and both sides are symmetrical parallel.The plane type of the wing wall water outlet energy dissipation section is set to "eight character" type or straight line type, and the inclination angle α straight line type is 0 DEG, and the inclination angle α "eight character" type is less than or equal to 10 DEG, and the top elevation gradually reduces from upstream to downstream, and is flush with the bottom plate at the tail of water outlet energy dissipation section.

[0009] Further, the wing wall cross section adopts practical weir type or rectangular cross section type, the wing wall top elevation is determined according to the height of design maximum flow trial and error calculation height plus appropriate wave height, and the wave height is generally 3-5cm, the wing wall is made of reinforced concrete, the circular arc radius R is set to 0.5-1.0 times of the top width of stable measuring section, and the wing wall thickness is 20-40cm.

[0010] Further, the bottom plate thickness is set to 10-30cm, the bottom plate elevation gradually increases from the side contraction to the stable flow measuring section, the front end is naturally connected with the riverbed, the rear end is connected with the stable flow measuring section, the water-approaching end is set to a slope type or an arc type for lifting, the elevation of the inlet of the bottom plate stable flow measuring section is set to the corresponding water level of the 70% stable flow measuring section inlet corresponding to the design maximum flow of the flow measuring tank, the whole bottom plate gradually decreases from the upstream to the downstream according to the design gradient, the length of the bottom plate stable flow measuring section is set to 3-5 times of the top width, the bottom plate water-out energy dissipation section gradually decreases to be naturally connected with the riverbed, and the arc-shaped connection is adopted between the bottom plate water-in gradual change section, the stable flow measuring section and the water-out energy dissipation section.

[0011] Further, the minimum water depth of the section design is not less than 8cm, the top height design should consider the influence of wave height, and generally, 3-5cm is recommended. When the flow measurement amplitude is small, the rectangular section is adopted; when the flow amplitude is large, the trapezoidal section is adopted, and attention should be paid to the vertical line not being arranged on the slope, the number of vertical lines is generally not less than 3, and the distance between the first and last vertical lines to the two sides of the flow measuring tank is recommended to be controlled between 0.5-1.0m, and the maximum is not more than 1.5m.

[0012] Further, the tooth wall is constructed only on the upstream water-approaching surface and the downstream energy dissipation section when the river channel is narrow and the bottom plate is integrally poured along the river bottom; the tooth wall is constructed around the bottom of the flow measuring tank when the river channel is wide and the bottom plate cannot be integrally poured along the river bottom; the thickness of the tooth wall is 20-40cm, and the buried depth is determined according to the riverbed scouring investigation results and the riverbed composition.

[0013] Further, the energy dissipation body adopts a ladder step type or a rivet type, and a slope type can be adopted when the downstream anti-scour requirement is not high; when the rivet type is adopted, the rivet is integrally poured with the bottom plate, the upper part is a hemisphere, the lower part is a cylinder, and the buried depth is the same as the thickness of the bottom plate; the depth gauge is arranged at the flow monitoring section at the position close to the downstream 2 / 3 position of the stable flow measuring section, and the operation platform is arranged on the outside of the bottom plate of the flow monitoring section.

[0014] The low-water flow measuring tank is an artificial water tank with specific size and regular shape, which is used for controlling hydrological monitoring low-water flow conditions and measuring low-water flow in a specific range. The low-water flow measuring tank is suitable for mountain rivers with moderate catchment area, non-wandering riverbed, certain fall, less influence of wading engineering and no special requirements for river management. The low-water flow measuring tank mainly solves the low-water flow monitoring problem under special conditions such as river flow bifurcation, shallow water depth and disorderly flow direction.

[0015] The utility model discloses the technical scheme beneficial effect has: first, the effective design control of low water measuring flume is carried out, makes the measuring flume construction position, the gradient selection more reasonable, the height control of wing wall, inlet more appropriate, makes the measuring flume more can satisfy the actual need of flow monitoring, second, the design scheme has been considered comprehensively, makes the appearance design of measuring flume more appropriate, further avoids the vacuum negative pressure damage and along the river submergence, scour and so on prior art problem, improves the practical application efficacy of low water measuring flume. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the technical scheme in the embodiment of the utility model or prior art, below will to the drawing needed to be used in the embodiment or prior art description simple introduction, obviously, the drawing in the following description only some embodiments of the utility model, for the ordinary skilled person in the art comes, under the premise of not paying the creative labor intensity, can also obtain other drawings according to these drawings.

[0017] Figure 1 It is the low water measuring flume rectangular tank perspective view and sectional view schematic drawing of the utility model;

[0018] Figure 2 It is the low water measuring flume trapezoidal tank perspective view and sectional view schematic drawing of the utility model;

[0019] Figure 3 It is the low water measuring flume compound combination tank perspective view and sectional view schematic drawing of the utility model;

[0020] Figure 4 It is the low water measuring flume rectangular tank perspective schematic drawing of the utility model;

[0021] Figure 5 It is the low water measuring flume rectangular tank sectional view schematic drawing of the utility model;

[0022] Figure 6 It is the low water measuring flume trapezoidal tank perspective schematic drawing of the utility model;

[0023] Figure 7 It is the low water measuring flume trapezoidal tank sectional view schematic drawing of the utility model;

[0024] Figure 8 It is the low water measuring flume compound combination tank perspective schematic drawing of the utility model;

[0025] Figure 9 It is the low water measuring flume compound combination tank sectional view schematic drawing of the utility model;

[0026] Figure 10 It is the low water measuring flume wing wall type schematic drawing of the utility model Figure 1 ;

[0027] Figure 11 Low water measuring flume wing wall type of the utility model Figure 2 ;

[0028] Figure 12 Low water measuring flume wing wall structure of the utility model Figure 1 ;

[0029] Figure 13 Low water measuring flume wing wall structure of the utility model Figure 2 ;

[0030] Figure 14 Low water measuring flume bottom plate structure of the utility model Figure 1 ;

[0031] Figure 15 Low water measuring flume bottom plate structure of the utility model Figure 2 ;

[0032] Figure 16 Low water measuring flume bottom plate structure of the utility model Figure 3 ;

[0033] Figure 17 Low water measuring flume section structure of the utility model Figure 1 ;

[0034] Figure 18 Low water measuring flume section structure of the utility model Figure 2 ;

[0035] Figure 19 Low water measuring flume section structure of the utility model Figure 3 ;

[0036] Figure 20 Low water measuring flume tooth wall structure of the utility model Figure 1 ;

[0037] Figure 21 Low water measuring flume tooth wall structure of the utility model Figure 2 ;

[0038] Figure 22 Low water measuring flume ladder step type energy dissipator top view of the utility model

[0039] Figure 23 Low water measuring flume ladder step type energy dissipator shaft side view of the utility model

[0040] Figure 24 Low water measuring flume ladder step type energy dissipator front view of the utility model

[0041] Figure 25 Low water measuring flume ladder step type energy dissipator right view of the utility model

[0042] Figure 26 It is the rivet type energy dissipation body of low water measuring flume and is a top view schematic diagram;

[0043] Figure 27 It is the rivet type energy dissipation body of low water measuring flume and is a side view schematic diagram;

[0044] Figure 28 It is the rivet type energy dissipation body of low water measuring flume and is a front view schematic diagram;

[0045] Figure 29 It is the rivet type energy dissipation body of low water measuring flume and is a right view schematic diagram;

[0046] In the drawing: 1, rectangular groove; 2, trapezoidal groove; 3, complex combined groove; 4, wing wall; 5, bottom plate; 6, tooth wall; 7, energy dissipation body. DETAILED DESCRIPTION

[0047] The technical solutions in the embodiments of the present application will be apparently and completely described below with reference to the drawings in the embodiments of the present application. Apparently, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0048] Basic conditions for low water measuring flume construction: The low water measuring flume is generally constructed downstream of the basic section or the measuring section, and it is appropriate to not affect the operation of the hydrological facilities and equipment, the medium and high water flow test and the water level monitoring, and it should have certain river section conditions and hydraulic conditions, and specifically should meet the following requirements: (1) The test river section has a certain water level difference and an allowable submerged amplitude, and will not cause great influence on the river channel because of the construction of the low water measuring flume. (2) The test river section has a relatively stable bank slope or is constructed with a dike, and if necessary, it is recommended to first regulate the bank slope and then construct the low water measuring flume. (3) The river channel has no special ecological management, navigation, drifting and other requirements.

[0049] Design preparation:

[0050] 1. Basic situation investigation

[0051] The investigation content includes the basic situation of the station, the situation of the test river section, the characteristics of the river basin, the water-related engineering, the river management and the influence investigation, etc.

[0052] 1.1. Investigation of the basic situation of the station

[0053] (1) Data collection

[0054] Investigate the station category and the main and auxiliary functions it undertakes, collect data on the catchment area, river slope, flood measurement standard and corresponding water level-flow, minimum cross-section flow, and other data. For stations with water ecological protection functions, collect ecological flow control indicators and control requirements. Investigate the dispersion of low-flow water level-flow relationship line, the flow variation amplitude of the same level, and the range of water level variation affected, etc.

[0055] (2) Investigation of monitoring conditions

[0056] Investigate the monitoring items, monitoring methods, and layout of monitoring facilities, focusing on the layout of riverfront monitoring facilities such as water level and flow. Investigate the layout of basic water gauge cross-sections, slope water gauge cross-sections, and float cross-sections, focusing on the type and positional relationship of each group of water gauges. Investigate the layout of flow monitoring facilities such as hydrological cableways and simple cableways, as well as other automatic flow measurement equipment such as radar or time difference method, focusing on the positional relationship with the basic water gauge cross-section.

[0057] (3) Investigation of test reach

[0058] Investigate the straight length of the river reach, cross-section shape, control conditions, riverbed composition and scouring and silting changes, bank slope composition and stability, crossing and temporary traffic, and water intake and discharge, etc. Investigate and analyze the composition and thickness of the riverbed, and evaluate the riverbed seepage conditions.

[0059] 1.2 Investigation of basin characteristics

[0060] (1) Natural geographical conditions

[0061] Investigate the topography, soil structure, and vegetation cover of the basin above the cross-section, as well as the basin slope, shape coefficient, and other conditions. Investigate the occurrence of natural disasters such as landslides and mudslides.

[0062] (2) Hydro-meteorology

[0063] Investigate the climate type, temporal and spatial distribution of precipitation, and intra-annual distribution of runoff in the basin.

[0064] (3) Investigation and analysis of low flow

[0065] Investigate the low-flow water production conditions. Mainly including the source of low-flow water, river dry-up conditions, and the occurrence of groundwater outflow in areas where groundwater recharge is dominant. Investigate the flow characteristics of low-flow water and the daily, ten-day, and monthly low-flow modulus, investigate or analyze and determine the minimum cross-section flow, and check the rationality.

[0066] (4) Investigation of water-crossing projects

[0067] Investigate the type (diversion, pumping, water transfer or water storage project), function, scale, regulation form (annual regulation, multi-year regulation, seasonal regulation or no regulation), operation mode and location relationship with the basic section of the water-related project such as reservoirs and hydropower stations. For upstream water-related projects, investigate the ecological flow control situation, including control indicators, release methods and control requirements. For downstream water-related projects, investigate the influence on low flow measurement and the impact on the low water level-flow relationship.

[0068] (5) Other influence investigation

[0069] Investigate whether there are river management, ecological protection and other special requirements.

[0070] 1.3, Construction impact analysis

[0071] (1) Analyze the possible scouring impact on the downstream after the construction of the low water measuring flume, including the impact on the riverbed, bank slope and water-related projects, etc.

[0072] (2) Analyze the possible submergence impact on the upstream after the construction of the low water measuring flume, including the impact range, height and submerged objects, etc.

[0073] 2, River section topographic survey

[0074] Draw the test river section topographic map, focusing on detailed measurement of the bank slope and underwater topography near and below the basic section, and the measurement accuracy should meet the needs of low water measuring flume design.

[0075] 3, Design of low water measuring flume

[0076] 3.1, Position determination

[0077] The low water measuring flume is generally built downstream of the hydrological station basic section or flow section. The distance from the basic section or flow section should fully consider the needs of flow measurement cableway or ADCP flow measurement facilities and equipment operation, and generally should be in the same direction as the water flow, which can be located in the middle of the river or appropriately close to the bank to facilitate flow measurement and avoid causing scouring to the downstream bank.

[0078] 3.2, Design flow

[0079] (1) Design flow range determination

[0080] It is generally recommended to determine according to the needs of flow measurement. Wide and shallow river can use the corresponding flow of 10% of the flood standard water level range to determine the design maximum flow; narrow and deep river uses the corresponding flow of 5% of the flood standard water level range to determine the design maximum flow. The minimum flow determined by the minimum dry flow or dry flow modulus calculation. Sites with ecological flow monitoring needs should meet the needs of ecological flow monitoring. In the case of meeting the low water flow test needs, the water level range can be appropriately reduced in specific design.

[0081] (2) Design roughness, slope and flow velocity

[0082] The low water flow tank is generally recommended to be poured with concrete, and the inside of the tank body is smooth. The roughness is recommended to be selected from 0.014 to 0.016; the slope should be considered to have appropriate water depth and flow velocity, which is convenient for manual wading flow measurement by using a current meter, and is generally 0.3‰ to 1‰. The design flow velocity is controlled at 0.1 to 1.0 m / s. Embodiment

[0083] As shown in Figures 1 to 9 , a shape of a low water flow tank, the low water flow tank is composed of a water inlet gradual change section, a stable flow measurement section and a water outlet energy dissipation section from upstream to downstream. The shape includes a rectangular tank 1, a trapezoidal tank 2 and a complex combined tank 3; the rectangular tank 1 is set as a flow tank with a rectangular cross-sectional shape in the stable flow measurement section, the trapezoidal tank 2 is set as a flow tank with a trapezoidal cross-sectional shape in the stable flow measurement section, and the complex combined tank 3 is set as a flow tank with a cross-sectional shape composed of two or more shapes in the stable flow measurement section.

[0084] The low water flow tank is composed of an upper section, a middle section and a lower section, wherein the upper section is the water inlet gradual change section, the middle section is the stable flow measurement section, and the lower section is the water outlet energy dissipation section. The water inlet gradual change section is a gradual contraction section for collecting low dry flow, the upper part is connected with the upstream of the natural river, and the lower part is connected with the stable flow measurement section. The stable flow measurement section is a straight and uniform section for forming stable flow for monitoring flow, the upper part is connected with the water inlet gradual change section, and the lower part is connected with the water outlet energy dissipation section. The water outlet energy dissipation section is a scattered water section for water recession and considering energy dissipation, the upper part is connected with the stable flow measurement section, and the lower part is connected with the downstream natural river.

[0085] Low-water flumes are commonly classified into three types based on the cross-sectional shape of their stable flow measurement section: rectangular, trapezoidal, and combined types. To facilitate the installation of velocity measuring plumb lines, "V"-shaped and "U"-shaped flumes are generally not recommended. Rectangular flume type 1 refers to a flume with a rectangular cross-sectional shape for its stable flow measurement section; this is the most common type and is generally suitable for rivers with small flow variations during low water periods. Trapezoidal flume type 2 refers to a flume with a trapezoidal cross-sectional shape for its stable flow measurement section; this is generally suitable for rivers with relatively large flow variations. Combined flume type 3 refers to a flume with a stable flow measurement section composed of two or more shapes; this is generally suitable for rivers with large flow variations where trapezoidal flume type 2 cannot meet the flow monitoring needs, or where there are graded control requirements for flow monitoring. Example

[0086] like Figures 1 to 29 As shown, a low-water flow measurement channel structure includes a base plate 5, wing walls 4, toothed walls 6, energy dissipation body 7, a depth gauge, and an operating platform. The base plate 5 is located at the bottom of the low-water flow measurement channel and is used to support the water flow. The wing walls 4 are located above the base plate 5 and connected to it. From upstream to downstream, they consist of three parts: an inlet transition section, a stable flow measurement section, and an outlet energy dissipation section, and are cast as a whole. The toothed walls 6 are embedded in the riverbed and constructed around the low-water flow measurement channel, with their tops connected to the base plate 5. The energy dissipation body 7 is cast together with the base plate 5. The depth gauge is set at the flow monitoring section of the stable flow measurement section, and the operating platform is located on the base plate 5 outside the monitoring section.

[0087] like Figures 10 to 13 As shown, the planar shape of the inlet transition section of the wing wall 4 is either an inverted V-shape or a straight line, connected to the stable flow measurement section by an arc. The arc angle θ is 90° for the straight line type and generally less than 90° for the inverted V-shape type. The upstream of the stable flow measurement section of the wing wall 4 is connected to the wing wall 4 of the inlet transition section, and its height is slightly lower than that of the wing wall 4 of the inlet transition section according to the gradient. The downstream of the wing wall 4 is connected to the wing wall 4 of the outlet energy dissipation section. The wing walls 4 on both sides of the stable flow measurement section of the wing wall 4 are arranged along the flow direction, symmetrically parallel on both sides. The planar shape of the outlet energy dissipation section of the wing wall 4 is either a V-shape or a straight line type. The inclination angle α is 0° for the straight line type and less than or equal to 10° for the V-shape type. The top elevation gradually decreases from upstream to downstream, until it is flush with the bottom plate 5 at the tail of the outlet energy dissipation section.

[0088] Preferably, the wing wall 4 adopts a practical weir type or a rectangular cross-section type. The top elevation of the wing wall 4 is determined by adding an appropriate wave height to the height calculated based on the maximum design flow rate trial and error. The wave height is 3 to 5 cm. The radius R of the arc of the wing wall 4 is set to 0.5 to 1.0 times the top width of the stable flow measurement section. It adopts a concrete reinforcement design. The thickness of the wing wall 4 is between 20 and 40 cm.

[0089] The structural design of the wing wall 4 is as follows:Figures 10 to 13 As shown, the wing wall 4 is located above and connected with the bottom plate 5, and is composed of a water inlet gradual change section, a stable flow measuring section and a water outlet energy dissipation section from upstream to downstream, and the whole is poured as a whole. The wing wall 4 design includes selection of cross-sectional type, determination of thickness, segmented layout of plane type, determination of top elevation, circular arc radius R, circular arc angle θ and inclination angle α. The cross-sectional type generally adopts a practical weir type, and when the conditions are not available, a rectangular cross-sectional type can be adopted. The top elevation is determined according to the trial and error calculation height of the maximum flow plus a proper wave height, and the wave height is recommended to be 3-5 cm. The circular arc radius R and the arc of the wing wall 4 should be determined comprehensively according to the straightness of the river section, the river width and the flow conditions, and the circular arc radius R is generally recommended to be 0.5-1.0 times of the top width of the stable flow measuring section. Considering the resistance to water flow impact, it is recommended to adopt a reinforced concrete design, and the thickness is between 20-40 cm.

[0090] (1) Water inlet gradual change section: The wing wall 4 of the water inlet gradual change section mainly guides the water flow to enter the stable flow measuring section smoothly and uniformly. According to the test control conditions, the plane type is generally selected as "inverted eight" type, and "one word" type is adopted when the near flow speed is small or the river section length is limited. The circular arc is connected with the stable flow measuring section, and the circular arc angle θ is determined according to the plane type, which is 90° for "one word" type and generally less than 90° for "inverted eight" type. The top elevation should ensure that the water flow in the design flow range enters the tank, and the water surface slope is appropriately higher than that of the stable flow measuring section.

[0091] (2) Stable flow measuring section: The upstream wing wall 4 of the stable flow measuring section is connected with the wing wall 4 of the water inlet gradual change section, and the height is slightly lower than that of the wing wall 4 of the water inlet gradual change section according to the slope (the top height of the wing wall 4 at the connection is equal); the downstream wing wall 4 is connected with the wing wall 4 of the water outlet energy dissipation section. The wing walls 4 on both sides of the stable flow measuring section are arranged along the flow direction, and are symmetrical and parallel on both sides. The top elevation is determined comprehensively according to the allowable submerged elevation of the submerged influence investigation and analysis and the flow measurement requirements, and is reduced along the river according to the design slope.

[0092] (3) Water outlet energy dissipation section: The water outlet energy dissipation section not only prevents the water flow from scouring the tail of the low water measuring flow tank and its downstream, but also prevents the downstream river section of the low water measuring flow tank from forming backwater or the low water measuring flow tank from forming submerged flow. The plane type is generally selected as "eight" type or straight line type. The inclination angle α should be selected in combination with the plane type, and the downstream anti-scouring requirement should be fully considered, and it is recommended to be 0-10°, which is 0° for straight line type and less than or equal to 10° for "eight" type. The top elevation gradually decreases from upstream to downstream, and is flush with the bottom plate 5 at the tail of the water outlet energy dissipation section. Embodiment

[0093] As Figures 14 to 19As shown, a low-water measuring flume structure, the bottom plate 5 thickness is set to 10-30 cm, the bottom plate 5 elevation gradually increases from the side contraction to the stable measuring section, the front end is naturally connected with the riverbed, the rear end is connected with the stable measuring section, and the water-approaching end is set to a slope type or an arc type for lifting; the elevation of the inlet of the bottom plate 5 stable measuring section is set to the corresponding water level of the 70% stable measuring section inlet corresponding to the design maximum flow of the measuring flume, the whole section bottom plate 5 gradually decreases from upstream to downstream according to the design gradient, the length of the bottom plate 5 stable measuring section is set to 3-5 times the top width; the water-outlet energy dissipation section of the bottom plate 5 gradually decreases to naturally connect with the riverbed; the water-inlet gradual section, the stable measuring section and the water-outlet energy dissipation section are arc-connected between each section.

[0094] (1) Water-inlet gradual section: the elevation of the bottom plate 5 gradually increases from the side contraction to the stable measuring section, the front end is naturally connected with the riverbed, the rear end is connected with the stable measuring section, and the water-approaching end is generally designed to be lifted in a slope type, and when the elevation difference is large, it can be lifted in an arc type, the specific application is determined according to the situation, and no unified requirement is made in the design. The length is determined according to the length of the water-inlet gradual section wing wall 4 and the arc angle θ.

[0095] (2) Stable measuring section: the elevation of the bottom plate 5 at the inlet of the stable measuring section is determined according to the corresponding water level of the 70% stable measuring section inlet corresponding to the design maximum flow of the measuring flume, and can be appropriately reduced when the conditions are limited. The whole section bottom plate 5 gradually decreases from upstream to downstream according to the design gradient. The length of the stable measuring section is generally 3-5 times the top width, and can be appropriately lengthened under the condition.

[0096] (3) Water-outlet energy dissipation section: the bottom plate 5 of the water-outlet energy dissipation section gradually decreases to naturally connect with the riverbed, and the length is determined according to the elevation of the bottom plate 5 at the end of the stable measuring section and the elevation of the riverbed. It should be noted that it cannot form a sharp drop or a serious drop. The water-inlet gradual section, the stable measuring section and the water-outlet energy dissipation section are generally arc-connected between each section, as shown in Figures 14 to 16

[0097] (4) Cross-section design:

[0098] ① Minimum water depth: the flow measurement in the flume is controlled by using the flowmeter method as the basic design condition, and the minimum water depth is determined according to the minimum water depth requirement of the current small propeller flowmeter and rotating cup flowmeter. It is recommended that the minimum water depth be not less than 8 cm.

[0099] ② Bottom width: the cross-section bottom width is determined according to the design minimum flow, roughness, gradient and minimum water depth.

[0100] ​③Top width and cross section type: cross section top width and cross section type should be considered in the design of maximum flow, roughness, slope, top height and bottom plate 5 elevation parameters, using trial and error method to determine. Top height design should consider the impact of wave height, generally recommended to reserve 3-5 cm. Cross section selection: when the flow amplitude is small, rectangular cross section is used; when the flow amplitude is large, trapezoidal cross section is used, and the vertical line should not be arranged on the slope, the number of vertical lines is generally not less than 3, and the distance between the first and last vertical lines to the two sides of the measuring flume is recommended to be controlled between 0.5-1.0 m, and the maximum is not more than 1.5 m; when trapezoidal cross section still cannot meet the requirements, or there is a requirement for hierarchical control of flow monitoring, composite combined cross section is used. The top width is determined according to the cross section type, design maximum flow and top elevation. Figures 17 to 19 Embodiment

[0101] As shown in Figures 20 to 21 , a low water measuring flume structure, the tooth wall 6 when the river is narrow, the bottom plate 5 is integrally poured along the river bottom, only the tooth wall 6 is built on the upstream water surface and the downstream energy dissipation section; when the river is wide, the bottom plate 5 cannot be integrally poured along the river bottom, the tooth wall 6 needs to be built around the bottom of the measuring flume; the thickness of the tooth wall 6 is 20-40 cm, and the buried depth is determined according to the riverbed scouring investigation results and the riverbed composition.

[0102] The following factors should be considered in the structure design of the tooth wall 6:

[0103] (1) Tooth wall 6 layout: ① When the river is narrow, the bottom plate 5 is integrally poured along the river bottom, only the tooth wall 6 can be built on the upstream water surface and the downstream energy dissipation section, as shown in Figure 20 ② When the river is wide, the bottom plate 5 cannot be integrally poured along the river bottom, the tooth wall 6 needs to be built around the bottom of the measuring flume, as shown in Figure 21 .

[0104] (2) Tooth wall 6 thickness and buried depth: combined with the need for flume body erosion prevention and water seepage prevention, the thickness is generally recommended to be 20-40 cm, and the buried depth is determined according to the riverbed scouring investigation results and the riverbed composition. The design depth must meet the following requirements: ① The design depth of the tooth wall 6 should be able to prevent the erosion of the low water measuring flume by the water flow; ② The tooth wall 6 should be able to avoid water seepage from the bottom of the measuring flume to the downstream of the measuring flume (play a water retaining role); ③ The measuring flume must be stable and anti-skid. For the anti-skid design of the tooth wall 6, it is designed during construction. The design of this measuring flume only designs the layout, buried depth and thickness of the tooth wall 6.

[0105] ​In the design of the specific tooth wall 6, if the sand and stone in the river bottom is accumulated shallowly and can be connected with the bedrock, the tooth wall 6 should be connected with the bedrock as much as possible. If the alluvium is thick and it is difficult to be connected with the bedrock, the depth of scour should be controlled by analyzing the maximum flood in the history to ensure the safety and stability of the measuring flume, and the analysis and calculation method can refer to the calculation method of the scour of the railway bridge. Embodiments

[0106] As shown in Figures 22 to 29 , a low-water measuring flume structure, the energy dissipater 7 adopts a ladder step or rivet type, and when the downstream anti-scour requirement is not high, a slope type can be adopted; when the rivet type is adopted, the rivet is integrally cast with the bottom plate 5, the upper part is a hemisphere, the lower part is a cylinder, and the buried depth is the same as the thickness of the bottom plate 5; the depth measuring staff is arranged at the flow monitoring section at the position of 2 / 3 downstream of the stable measuring section, and the operation platform is arranged on the outside of the flow monitoring section on the bottom plate 5.

[0107] The energy dissipater 7 is designed according to the conditions of the river channel, and generally adopts a ladder step or rivet type, and when the downstream anti-scour requirement is not high, a slope type can be adopted. The two energy dissipation forms are shown in Figures 22 to 25 and Figures 26 to 29 . When the rivet type is adopted, the rivet is integrally cast with the bottom plate 5, the upper part is a hemisphere, the lower part is a cylinder, and the buried depth is the same as the thickness of the bottom plate 5.

[0108] The depth measuring staff and the operation platform are designed, the depth measuring staff is arranged at the flow monitoring section at the position of 2 / 3 downstream of the stable measuring section, the staff zero height is consistent with the surface of the bottom plate 5, and the graduation accuracy can adopt 1cm or 5mm. The operation platform is arranged on the outside of the flow monitoring section on the bottom plate 5, and the length and width are suggested to be not less than 1.5m x 1.5m, and the height is generally 5-10cm.

[0109] The above only describes the preferred embodiments of the present application, and is not intended to limit the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A low water flume structure characterized by: The low-water measuring flume is composed of a water inlet gradual change section, a stable measuring section and a water outlet energy dissipation section from upstream to downstream. The shape of the low-water measuring flume comprises a rectangular groove (1), a trapezoidal groove (2) and a complex combined groove (3). The rectangular groove (1) is a measuring flume with a rectangular cross section shape in the stable measuring section, the trapezoidal groove (2) is a measuring flume with a trapezoidal cross section shape in the stable measuring section, and the complex combined groove (3) is a measuring flume with a cross section shape composed of two or more shapes in the stable measuring section.

2. A low water flow channel structure according to claim 1, characterized in that: The low-water measuring flume comprises a bottom plate (5), wing walls (4), tooth walls (6), energy dissipaters (7), a depth measuring gauge and an operation platform; the bottom plate (5) is located at the bottom of the low-water measuring flume and is used for bearing water flow; the wing walls (4) are located above the bottom plate (5) and are connected with the bottom plate (5); the tooth walls (6) are embedded in the riverbed and are built along the periphery of the low-water measuring flume, and the top of each tooth wall (6) is connected with the bottom plate (5); the energy dissipaters (7) are cast together with the bottom plate (5); the depth measuring gauge is arranged at the flow monitoring section of the stable measuring section; and the operation platform is located on the bottom plate (5) outside the monitoring section.

3. A low water flow channel structure according to claim 2, characterized in that: The plane type of the water inlet gradual change section of the wing wall (4) is designed as an inverted eight-shaped type or a straight line type, and a circular arc is adopted to connect the stable measuring section, the circular arc angle θ of the straight line type is 90°, and the circular arc angle θ of the inverted eight-shaped type is generally less than 90°; the upstream wing wall (4) of the stable measuring section is connected with the wing wall (4) of the water inlet gradual change section, and the height of the upstream wing wall (4) is slightly lower than the height of the wing wall (4) of the water inlet gradual change section according to the gradient; the downstream wing wall (4) of the stable measuring section is connected with the wing wall (4) of the water outlet energy dissipation section; the left and right wing walls (4) of the stable measuring section are arranged along the flow direction and are symmetrical and parallel to each other; the plane type of the wing wall (4) of the water outlet energy dissipation section is designed as an eight-shaped type or a straight line type, and the inclination angle α of the straight line type is 0°, and the inclination angle α of the eight-shaped type is less than or equal to 10°; the top elevation of the wing wall (4) gradually decreases from upstream to downstream, and the top of the wing wall (4) of the water outlet energy dissipation section is flush with the bottom plate (5).

4. A low water flow channel structure according to claim 3, characterized in that: The cross section of the wing wall (4) adopts a practical weir type or a rectangular cross section type, and the wing wall (4) is made of reinforced concrete.

5. The low water flow channel structure according to claim 2, characterized by: The elevation of the bottom plate (5) gradually increases from the side contraction to the stable measuring section, the front end of the bottom plate (5) is naturally connected with the riverbed, and the rear end of the bottom plate (5) is connected with the stable measuring section; the water-approaching end of the bottom plate (5) is designed as a slope type or an arc type to be lifted.

6. A low water flow channel structure according to claim 5, characterized in that: The elevation of the bottom plate (5) at the inlet of the stable measuring section is designed as the corresponding water level at the inlet of the stable measuring section corresponding to 70% of the maximum flow of the measuring flume, and the whole bottom plate (5) gradually decreases from upstream to downstream according to the designed gradient; the bottom plate (5) gradually decreases to be naturally connected with the riverbed at the water outlet energy dissipation section, and the bottom plate (5) is connected with each section of the water inlet gradual change section, the stable measuring section and the water outlet energy dissipation section by an arc.

7. The low water flow channel structure according to claim 2, characterized by: When the river is relatively narrow and the bottom plate (5) is integrally cast along the riverbed, the tooth walls (6) are only built on the upstream water-approaching surface and the downstream energy dissipation section; when the river is relatively wide and the bottom plate (5) cannot be integrally cast along the riverbed, the tooth walls (6) are built around the bottom of the measuring flume.

8. The low water flow channel structure according to claim 2, characterized by: The energy dissipater (7) adopts ladder type or rivet type, and adopts slope type when the downstream anti-impact requirement is not high; when the rivet type is adopted, the rivet is integrally cast with the bottom plate (5), the upper part is a hemisphere, the lower part is a cylinder, and the buried depth is the same as the thickness of the bottom plate (5); the depth measuring staff is arranged at the flow monitoring section at the position close to the downstream 2 / 3 position of the stable flow measuring section, and the operation platform is arranged on the outside of the bottom plate (5) of the flow monitoring section.

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