CN112633554A - Method and device for predicting slope laminar flow velocity correction coefficient - Google Patents
Method and device for predicting slope laminar flow velocity correction coefficient Download PDFInfo
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Abstract
The invention provides a method and a device for predicting a slope laminar flow velocity correction coefficient, which comprises the following steps: paving a ground surface covering object at the bottom of an obliquely arranged scouring water tank to simulate the covering condition of a natural slope surface; adjusting the inclination angle of the scouring water tank to simulate the gradient of a natural slope; providing stable water flow for the washing water tank, and adjusting a water flow parameter value to a test target flow; measuring the surface flow velocity and the water depth of the thin-layer water flow in the scouring water tank, further calculating the submergence degree of the thin-layer water flow in the scouring water tank on the ground surface covered objects, and the average flow velocity, Reynolds number and correction coefficient of the thin-layer water flow in the scouring water tank; and respectively establishing a non-submerged state and submerged state downhill surface thin layer water flow velocity correction coefficient prediction model according to the submergence degree. The method can effectively improve the prediction precision of the correction coefficient and the calculation precision of the average flow velocity, provide a theoretical basis for carrying out hydrodynamic research on the slope sheet flow, and reduce the experimental research cost.
Description
Technical Field
The invention relates to the technical field of surface hydrological processes, in particular to a method and a device for predicting a slope laminar flow velocity correction coefficient.
Background
The depth of water of the slope laminar flow is generally only millimeter-sized to several centimeters, and many flow velocity measuring instruments cannot directly measure the flow velocity of the laminar flow due to the limitation of the depth of water. Therefore, in practice, the flow velocity of the dome sheet flow is usually measured by a dyeing tracer method, and the flow velocity obtained by the method is the surface flow velocity of the dome sheet flow. However, the flow rate parameter used in the hydrological model and the hydraulics calculation is the average flow rate, and in order to obtain the average flow rate of the water flow, the surface flow rate needs to be multiplied by a flow rate correction coefficient alpha. Currently, a great deal of research is conducted on the flow rate correction coefficient as a constant value, and the values of α are usually 0.67 (laminar flow), 0.70 (transition flow) and 0.80 (turbulent flow) according to different flow regimes.
The natural slope surface is distributed with a large number of rough elements with different sizes, such as stones, herbs, dried falling objects and the like. When the sheet water flows through the rough elements, the characteristics (such as flow speed and water depth) of the water flow can be obviously changed along with the change of the submerging conditions of the rough elements. Thus, the vertical flow velocity distribution of the laminar water flow is no longer logarithmic under different flooding conditions, but exhibits an irregular distribution pattern, such as an S-shaped distribution. At this time, the correction coefficient α is also changed accordingly, and the value of α is no longer constant. Therefore, under the condition that the slope surface is covered by rough elements, the appropriate and accurate flow rate correction coefficient value is determined, and the calculation precision of the average flow rate is directly related.
Disclosure of Invention
The invention provides a method and a device for predicting a slope surface laminar flow velocity correction coefficient, which are used for solving the defect that the slope surface laminar flow velocity correction coefficient under a coating condition cannot be predicted in the prior art, realizing accurate prediction and simplicity and feasibility of the laminar flow velocity correction coefficient under the coating condition, and providing theoretical basis and technical support for carrying out slope surface velocity measurement and related hydrological calculation in the field.
The invention provides a method for predicting a slope surface laminar flow velocity correction coefficient, which comprises the following steps:
paving a ground surface covering object at the bottom of the scouring water tank to simulate the covering condition of a natural slope surface;
adjusting the inclination angle of the scouring water tank to simulate the slope of a natural slope;
providing stable water flow to the washing water tank, and adjusting a water flow parameter value to a test target flow;
measuring the surface flow velocity and the water depth of the thin-layer water flow in the scouring water tank, and further calculating the submergence degree of the thin-layer water flow in the scouring water tank on the ground surface covering objects, and the average flow velocity, Reynolds number and correction coefficient of the thin-layer water flow in the scouring water tank;
and respectively establishing a non-submerged state and submerged state downhill surface thin layer water flow velocity correction coefficient prediction model according to the submergence degree.
According to the method for predicting the slope surface laminar water flow velocity correction coefficient provided by the invention, in the step of laying the surface covering object at the bottom of the scouring water tank and simulating the natural slope surface covering condition, the method further comprises the following steps:
and laying a simulated soil layer at the bottom of the flushing water tank, and laying the ground surface covering object with a set size on the surface of the simulated soil layer according to a set covering proportion Cr.
According to the method for predicting the slope sheet water flow velocity correction coefficient provided by the invention, in the step of providing stable water flow to the washing water tank and adjusting the water flow parameter value to the test target flow, the method further comprises the following steps:
the flow of the water flow entering the scouring water tank is adjusted to a test target flow Q by adjusting a variable frequency water pump and a ball valve on a connecting pipeline of the water supply water tank and the scouring water tank.
According to the method for predicting the correction coefficient of the flow velocity of the thin layer water flow on the slope surface, the steps of measuring the surface flow velocity and the water depth of the thin layer water flow in the flushing water tank, further calculating the submergence degree of the thin layer water flow in the flushing water tank on the ground surface covering objects, and calculating the average flow velocity, Reynolds number and correction coefficient of the thin layer water flow in the flushing water tank further comprise:
setting a plurality of flow velocity measurement sections along the inclined direction of the flushing water tank, setting intervals between two adjacent flow velocity measurement sections, setting a plurality of flow velocity measurement points on each flow velocity measurement section, adopting a dyeing tracing method to repeatedly measure the surface flow velocity of the laminar flow at each flow velocity measurement point, calculating the average value of the flow velocity measurement values of each flow velocity measurement point and each flow velocity measurement section, and further obtaining the surface flow velocity V of the laminar flow on the slope surfaces。
The method for predicting the slope sheet water flow velocity correction coefficient provided by the invention further comprises the following steps:
and a plurality of bathymetric sections are arranged along the inclined direction of the scouring water tank, the interval between every two adjacent bathymetric sections is set, each bathymetric section is provided with a plurality of bathymetric point positions, each bathymetric point position adopts a water level probe to repeatedly measure the water depth of the laminar flow, the average value of the bathymetric values of each bathymetric point position and each bathymetric section is calculated, and the water depth h of the slope laminar flow is obtained.
The method for predicting the slope sheet water flow velocity correction coefficient provided by the invention further comprises the following steps:
calculating and obtaining the submergence degree Lambda of the water flow in the scour water tank to the surface covering object through the water depth h of the thin-layer water flow and the size value k of the surface covering object,
the method for predicting the slope sheet water flow velocity correction coefficient provided by the invention further comprises the following steps:
calculating the calculated value V of the average flow velocity of the slope laminar flow according to the flow value Q and the water depth h of the laminar flowm，
w＝W×(1-Cr)
Wherein w is the effective water flow width; w is the width of the flushing water tank, and Cr is the coating proportion of the ground surface coating.
The method for predicting the slope sheet water flow velocity correction coefficient provided by the invention further comprises the following steps:
calculating value V according to water depth h and average flow velocity of laminar water flowmCalculating the Reynolds number Re of the slope sheet water flow,
wherein v is the viscosity coefficient of water, t is the temperature of water, and q is the single width flow.
According to the method for predicting the slope surface laminar flow velocity correction coefficient provided by the invention, in the step of establishing the correction coefficient prediction model according to the submergence, the method further comprises the following steps:
according to the measured superficial velocity V of the laminar water flowsAnd calculated value V of flow velocitymCalculating the correction coefficient calculation value alpha of the laminar water flow velocity,
a correction coefficient prediction model is established,
α＝a×logRe+b×logΛ-c×logS+dΛ＜1
α＝a×logRe-b×logΛ-c×logS+dΛ≥1
wherein a, b, c and d are regression prediction model coefficients, and S is the inclination angle of the flushing water tank.
The invention also provides a device for predicting the velocity correction coefficient of the slope surface thin layer water flow, which comprises a water supply water tank, a steady flow water tank and a flushing water tank, wherein the water supply water tank is connected with the steady flow water tank through a conveying pipeline;
the steady flow water tank is internally provided with a baffle with holes, the baffle with holes divides the steady flow water tank into a first steady flow area and a second steady flow area, the conveying pipeline is connected with the first steady flow area, and the second steady flow area is communicated with the first end of the flushing water tank;
the scouring water tank is arranged on the support frame, the second end of the scouring water tank is hinged to the support frame, the support frame is provided with a hydraulic cylinder, and the output end of the hydraulic cylinder is hinged to the bottom side of the first end of the scouring water tank.
The invention provides a method and a device for predicting a slope sheet current velocity correction coefficient, which are characterized in that the setting of natural slope coating conditions, the setting of simulated gradient, the setting of flow, the measurement of surface flow velocity, water depth and submergence are simulated in a flushing water tank, the average flow velocity value, Reynolds number and correction coefficient are obtained by calculation, further correction coefficient prediction models under non-submerging and submerging conditions are respectively established, the predicted value of the correction coefficient is used for replacing a constant value in the traditional research, the correction coefficient prediction precision and the average flow velocity calculation precision can be effectively improved, and theoretical basis is provided for further carrying out slope sheet current hydrodynamic research; the method reduces the experimental research cost, is suitable for carrying out the hydrological research work on the slope in the field, and has very wide universality.
Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and those skilled in the art can also obtain other drawings according to the drawings without creative efforts.
FIG. 1 is a schematic structural diagram of a slope sheet water flow velocity correction coefficient prediction device according to the present invention;
FIG. 2 is a schematic plan view of a slope surface of a surface covering layer of the device for predicting a coefficient of flow velocity of sheet water on the slope surface according to the present invention;
FIG. 3 is a linear graph comparing the predicted value and the measured value of the correction coefficient of the flow velocity of the thin layer on the lower slope of the simulated gravel coating.
Reference numerals:
100. a water supply tank; 200. a delivery line; 210. a variable frequency water pump; 220. an electromagnetic flow meter; 230. a ball valve; 300. a steady flow water tank; 310. a baffle plate with holes; 400. flushing the water tank; 410. a support frame; 420. a hydraulic cylinder; 430. measuring the section in water depth; 440. a water level probe; 450. covering the ground.
Detailed Description
The embodiments of the present invention will be described in further detail with reference to the drawings and examples. The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention.
In the description of the embodiments of the present invention, it should be noted that the terms "center", "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience in describing the embodiments of the present invention and simplifying the description, but do not indicate or imply that the referred devices or elements must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the embodiments of the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
In the description of the embodiments of the present invention, it should be noted that, unless explicitly stated or limited otherwise, the terms "connected" and "connected" are to be interpreted broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; may be directly connected or indirectly connected through an intermediate. Specific meanings of the above terms in the embodiments of the present invention can be understood in specific cases by those of ordinary skill in the art.
In embodiments of the invention, unless expressly stated or limited otherwise, the first feature "on" or "under" the second feature may be directly contacting the first and second features or indirectly contacting the first and second features through intervening media. Also, a first feature "on," "over," and "above" a second feature may be directly or diagonally above the second feature, or may simply indicate that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lesser elevation than the second feature.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of an embodiment of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.
The method for predicting the slope laminar flow velocity correction coefficient according to the present invention is described below with reference to fig. 1 and 2, and includes the following steps:
paving a ground surface covering object 450 at the bottom of the scouring water tank 400 to simulate the covering condition of a natural slope surface;
adjusting the inclination angle of the flushing water tank 400 to simulate the slope of a natural slope;
providing a stable water flow to the wash tank 400 and adjusting a water flow parameter value to a test target flow;
measuring the surface flow velocity and the water depth of the thin layer water flow in the flushing water tank 400, and further calculating the submergence degree of the thin layer water flow in the flushing water tank 400 on the surface covering object 450, and the average flow velocity, Reynolds number and correction coefficient of the thin layer water flow in the flushing water tank 400;
and respectively establishing a non-submerged state and submerged state downhill surface thin layer water flow velocity correction coefficient prediction model according to the submergence degree.
According to the method for predicting the slope surface laminar water flow velocity correction coefficient provided by the invention, the step of laying the surface covering object 450 at the bottom of the flushing water tank 400 and simulating the natural slope surface covering condition further comprises the following steps:
and laying a simulated soil layer at the bottom of the flushing water tank 400, and laying the ground surface covering object 450 with a set size on the surface of the simulated soil layer according to a set covering proportion Cr.
According to the method for predicting the slope sheet water flow velocity correction coefficient provided by the invention, in the step of providing stable water flow to the flushing water tank 400 and adjusting the water flow parameter value to the test target flow, the method further comprises the following steps:
the flow rate of the water flow entering the flushing water tank 400 is adjusted to the test target flow rate Q by adjusting the variable frequency water pump 210 and the ball valve 230 on the connecting pipeline of the water supply tank 100 and the flushing water tank 400.
According to the method for predicting the correction coefficient of the flow velocity of the sheet water flow on the slope surface, the steps of measuring the surface flow velocity and the water depth of the sheet water flow in the flushing water tank 400, further calculating the submergence degree of the sheet water flow in the flushing water tank 400 on the surface covering object 450, and calculating the average flow velocity, Reynolds number and correction coefficient of the sheet water flow in the flushing water tank 400 further comprise:
setting a plurality of flow velocity measurement sections along the inclined direction of the flushing water tank 400, setting the interval between every two adjacent flow velocity measurement sections, setting a plurality of flow velocity measurement points on each flow velocity measurement section, adopting a dyeing tracing method to repeatedly measure the surface flow velocity of the laminar flow at each flow velocity measurement point, calculating the average value of the flow velocity measurement values of each flow velocity measurement point and each flow velocity measurement section, and further obtaining the surface flow velocity V of the laminar flow on the slope surfaces。
The method for predicting the slope sheet water flow velocity correction coefficient provided by the invention further comprises the following steps:
a plurality of bathymetric sections 430 are arranged along the inclined direction of the flushing water tank 400, the interval between every two adjacent bathymetric sections 430 is set, each bathymetric section 430 is provided with a plurality of bathymetric point positions, each bathymetric point position adopts a water level probe 440 to repeatedly measure the bathymetry of the laminar flow, the average value of the bathymetric values of each bathymetric point position and each bathymetric section 430 is calculated, and then the water depth h of the slope laminar flow is obtained.
The method for predicting the slope sheet water flow velocity correction coefficient provided by the invention further comprises the following steps:
calculating and obtaining the submergence degree Lambda of the water flow in the flushing water tank 400 on the surface covering object 450 through the depth h of the water flow and the size value k of the surface covering object 450,
the method for predicting the slope sheet water flow velocity correction coefficient provided by the invention further comprises the following steps:
calculating the calculated value V of the average flow velocity of the slope laminar flow according to the flow value Q and the water depth h of the laminar flowm，
w＝W×(1-Cr)
Wherein w is the effective water flow width; w is the width of the flush tank 400, and Cr is the coating ratio of the surface coating 450.
The method for predicting the slope sheet water flow velocity correction coefficient provided by the invention further comprises the following steps:
calculating value V according to water depth h and average flow velocity of laminar water flowmCalculating the Reynolds number Re of the slope sheet water flow,
wherein v is the viscosity coefficient of water, t is the temperature of water, and q is the single width flow.
According to the method for predicting the slope surface laminar flow velocity correction coefficient provided by the invention, in the step of establishing the correction coefficient prediction model according to the submergence, the method further comprises the following steps:
according to the measured superficial velocity V of the laminar water flowsAnd calculated value V of flow velocitymCalculating a water flow velocity correction coefficient calculation value alpha,
a correction coefficient prediction model is established,
α＝a×logRe+b×logΛ-c×logS+dΛ＜1
α＝a×logRe-b×logΛ-c×logS+dΛ≥1
wherein a, b, c and d are regression prediction model coefficients, and S is the inclination angle of the flushing water tank.
The invention provides a method for predicting a slope laminar flow velocity correction coefficient, which comprises the following specific steps:
step 1, arranging a simulated slope surface thin layer
Firstly, filling test soil in layers at the bottom of a washing water tank 400, or pasting screened soil and sand grains at the bottom of the washing water tank 400, or pasting coarse sand paper at the bottom of the washing water tank 400, and completing soil layer simulation;
then, ground surface covering objects 450 with certain sizes, such as stones, litter and the like, are distributed on the surface of the soil layer according to a certain covering proportion Cr and a certain arrangement mode to complete the simulation of the covering objects, so that the simulation of the covering condition of the natural slope surface is completed.
Step 2, setting gradient
The inclination angle of the flushing water tank 400 is adjusted to simulate the slope of a natural slope.
Step 3, setting the water flow
And (3) opening the variable frequency water pump 210 on the connecting pipeline of the water supply tank 100 and the flushing water tank 400, adjusting the opening of the ball valve 230, setting the flow parameter of the electromagnetic flowmeter 220 to the test target flow Q, and finishing the test flow setting after the water flow is stable.
Step 4, measuring the flow velocity of water flow
The slope direction of the flushing water tank 400 is provided with a plurality of flow rate measurement sections, two adjacent flow rate measurement sections are arranged at intervals, each flow rate measurement section is provided with a plurality of flow rate measurement points, each flow rate measurement point adopts a dyeing tracing method to repeatedly measure the surface layer flow rate of the thin layer water flow, the average value of the flow rate measurement values of the flow rate measurement points and each flow rate measurement section is calculated, and the average value of the flow rate measurement values of the thin layer water flow on the downhill surface of the test working condition is finally calculated, namely the surface layer flow rate V of the thin layer water flow on the downhill surface, namely the surface layer flows。
Step 5, measuring the water depth of the laminar water flow
A plurality of bathymetric sections 430 are arranged along the inclined direction of the scour water tank 400, the interval between every two adjacent bathymetric sections 430 is set, each bathymetric section 430 is provided with a plurality of bathymetric point positions, each bathymetric point position adopts a water level probe 440 to repeatedly measure the bathymetry of the laminar flow, the average value of the bathymetric values of each bathymetric point position and each bathymetric section 430 is calculated, and finally the average bathymetry h of the laminar flow on the downhill surface of the test working condition is calculated.
Step 6, calculating the inundation degree
Calculating and obtaining the submergence degree Lambda of the water flow in the flushing water tank 400 on the surface covering object 450 through the depth h of the water flow and the size value k of the surface covering object 450,
if Λ is less than 1, the ground surface covering object 450 is in an unsubmerged state; if Λ is not less than 1, the surface covering object 450 is in a submerged state.
Step 7, obtaining the calculated value of the average flow velocity
Calculating the calculated value V of the average flow velocity of the slope laminar flow according to the flow value Q and the water depth h of the laminar flowm，
w＝W×(1-Cr)
Wherein w is the effective water flow width; w is the width of the flush tank 400, and Cr is the coating ratio of the surface coating 450.
Step 8, calculating Reynolds number
Calculating value V according to water depth h and average flow velocity of laminar water flowmCalculating the Reynolds number Re of the slope sheet water flow,
wherein v is the viscosity coefficient of water, t is the temperature of water, and q is the single width flow.
Step 9, calculating correction coefficient
According to the measured water flow velocity VsAnd calculated value V of flow velocitymCalculating the correction coefficient calculation value alpha of the laminar water flow velocity,
step 10, establishing a correction coefficient prediction model
The degree of flooding is adjusted, the target flow, the gradient and the coating proportion are changed, and a plurality of groups of working conditions are set. And (4) repeating the steps 1-9 to obtain the calculated value of the flow speed correction coefficient under each working condition, and establishing a correction coefficient database under each working condition.
And establishing a correction coefficient prediction model by utilizing the correction coefficient database according to a stepwise linear regression method. Since the inundation degree and the correction coefficient are in a non-monotonic relation, the correction coefficient prediction model is a piecewise function. And respectively establishing a correction coefficient prediction model under a non-submerged state and a correction coefficient prediction model under a submerged state by taking the submergence as a division basis. The independent variables of the correction coefficient prediction model comprise the Reynolds number, the inundation degree and the gradient.
α＝a×logRe+b×logΛ-c×logS+dΛ＜1
α＝a×logRe-b×logΛ-c×logS+dΛ≥1
Wherein a, b, c and d are regression prediction model coefficients, and S is the inclination angle of the flushing water tank.
Examples
In the embodiment, the length of the washing water tank 400 is 6m, the width of the washing water tank is 0.5m, and the gradient adjusting range is 0-15 degrees; simulating gravel by using a plastic hemisphere, wherein the diameter of the gravel is 2cm, the measured value k is 1cm, the gravel is arranged in a plum blossom shape, the covering degrees of the gravel are respectively 10%, 20% and 30%, 5 slopes are arranged, and the slopes are respectively 2 degrees, 4 degrees, 6 degrees, 8 degrees and 10 degrees; setting 9 flow rates of 5.63 liters/min, 8.44 liters/min, 11.26 liters/min, 22.52 liters/min, 45.03 liters/min, 70.36 liters/min, 84.43 liters/min, 100.00 liters/min, and 122.00 liters/min, respectively; this example performed a total of 135 trials.
A piece of sandpaper cloth (with a grit size of 0.25mm) was adhered to the bottom of the scour tank 400 to simulate a rough soil layer. Plastic hemispheres with the diameter of 2cm are distributed on the surface of the soil layer in a plum blossom arrangement mode, and the coverage degrees Cr of the gravels are respectively set to be 10%, 20% and 30%;
the slope of the flushing water tank 400 is adjusted to 2 degrees, 4 degrees, 6 degrees, 8 degrees and 10 degrees by using the hydraulic cylinder 420;
turning on the variable-frequency water pump 210 and the ball valve 230, and setting and adjusting the flow of the electromagnetic flow meter 220 to a test target flow Q, which is set to 5.63L/min, 8.44L/min, 11.26L/min, 22.52L/min, 45.03L/min, 70.36L/min, 84.43L/min, 100.00L/min, and 122.00L/min, respectively;
the method comprises the following steps of (1) setting 5 flow velocity measurement sections from the top of a slope to the bottom of the slope along the water flow direction, wherein the distance between the two flow velocity measurement sections is 1m, setting 4 measurement points on each flow velocity measurement section, and measuring the flow velocity at each measurement point for 5 times by using a dyeing tracing method, so that 100 flow velocity measurement values are obtained in each test working condition, and calculating the average value of the 100 flow velocity measurement values to obtain the surface layer flow velocity of the thin-layer water flow on the downhill surface of the test working condition;
totally setting 5 water depth measurement sections 430(1.70m, 2.70m, 3.70m, 4.70m and 5.70m) from the top to the bottom of the slope along the water flow direction, setting 4 measurement point positions on each water depth measurement section 430, and measuring the water depth at each measurement point position for 3 times by using a water level probe 440, so that each test working condition obtains 60 water depth measurement values, and calculating the average value of 60 water depths to obtain the average water depth of the laminar water flow on the downhill surface of the test working condition;
the degree of flooding a is calculated,
calculating the value V of the mean flow velocity of the water flowm，
w＝W×(1-Cr)
The reynolds number is calculated and calculated,
the correction coefficient is calculated by calculating the correction coefficient,
a correction coefficient prediction model is established,
α＝0.235log Re+0.219logΛ-0.107Λ＜1；
α＝0.311log Re-0.646logΛ-0.216logS-0.302Λ≥1。
as shown in fig. 3, the calculated value of the correction coefficient obtained by the test and the predicted value of the correction coefficient obtained by the prediction model are summarized, and it can be seen that the calculated value of the correction coefficient is well matched with the predicted value, which indicates that the method for predicting the coefficient of flow velocity of sheet water on the slope provided by the invention has higher prediction precision and can accurately predict the correction coefficient of flow velocity of sheet water on the slope under the coating condition.
As shown in fig. 1 and fig. 2, the present invention further provides a device for predicting a slope laminar flow velocity correction coefficient, which includes a water supply tank 100, a steady flow water tank 300 and a flushing water tank 400, wherein the water supply tank 100 is connected to the steady flow water tank 300 through a conveying pipeline 200, and the conveying pipeline 200 is sequentially provided with a variable frequency water pump 210, an electromagnetic flowmeter 220 and a ball valve 230 along a flow direction of water flow;
the steady flow water tank 300 is internally provided with a baffle plate 310 with holes, the steady flow water tank 300 is divided into a first steady flow area and a second steady flow area by the baffle plate 310 with holes, the conveying pipeline 200 is connected with the first steady flow area, and the second steady flow area is communicated with the first end of the flushing water tank 400;
the washing water tank 400 is arranged on a support frame 410, the second end of the washing water tank 400 is hinged with the support frame 410, the support frame 410 is provided with a hydraulic cylinder 420, and the output end of the hydraulic cylinder 420 is hinged with the bottom side of the first end of the washing water tank 400. It can be understood that the water supply tank 100 is used for providing a stable water source, and has a water outlet at the bottom side and is connected to the delivery pipe 200, and the variable frequency water pump 210, the electromagnetic flow meter 220 and the ball valve 230 are used for ensuring a constant flow rate during the test.
The steady flow water tank 300 is vertically provided with a baffle plate 310 with holes, the steady flow water tank 300 is divided into a first steady flow area and a second steady flow area, the conveying pipeline 200 is connected with the lower part of the first steady flow area of the steady flow water tank 300, flows into the second steady flow area through the baffle plate 310 with holes, and flows into the flushing water tank 400 after being fully overflowed, and the steady flow water tank 300 can reduce water flow turbulence to the maximum extent and is used for forming uniform laminar water flow.
Wherein, erode basin 400 and enclose to close by toughened glass bottom surface and toughened glass lateral wall and form, the bottom side that erodes basin 400 sets up the rubber pad, and support frame 410 is provided with hydraulic cylinder 420, and hydraulic cylinder 420's output is articulated with the first end that erodes basin 400, and the second end that erodes basin 400 is articulated with support frame 410 for simulate domatic under the natural state, can simulate bare land, the domatic, meadow and withered and fallen object cover etc.. The water source enters the stable water supply tank 100, and the water source provided by the water supply tank 100 flows through the variable frequency water pump 210, the electromagnetic flow meter 220 and the ball valve 230, flows out after flowing into the steady flow water tank 300, flows into the flushing water tank 400, flows through the simulated natural slope surface, and flows out.
The invention provides a method and a device for predicting a slope sheet current velocity correction coefficient, which are characterized in that the setting of natural slope coating conditions, the setting of simulated gradient, the setting of flow, the measurement of surface flow velocity, water depth and submergence are simulated in a flushing water tank, the average flow velocity value, Reynolds number and correction coefficient are obtained by calculation, further correction coefficient prediction models under non-submerging and submerging conditions are respectively established, the predicted value of the correction coefficient is used for replacing a constant value in the traditional research, the correction coefficient prediction precision and the average flow velocity calculation precision can be effectively improved, and theoretical basis is provided for further carrying out slope sheet current hydrodynamic research; the method reduces the experimental research cost, is suitable for carrying out the hydrological research work on the slope in the field, and has very wide universality.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
The above embodiments are merely illustrative of the present invention and are not to be construed as limiting the invention. Although the present invention has been described in detail with reference to the embodiments, it should be understood by those skilled in the art that various combinations, modifications or equivalents may be made to the technical solution of the present invention without departing from the spirit and scope of the technical solution of the present invention, and the technical solution of the present invention is covered by the claims of the present invention.
Claims (10)
1. A method for predicting a slope sheet water flow velocity correction coefficient is characterized by comprising the following steps:
paving a ground surface covering object at the bottom of the scouring water tank to simulate the covering condition of a natural slope surface;
adjusting the inclination angle of the scouring water tank to simulate the slope of a natural slope;
providing stable water flow to the washing water tank, and adjusting a water flow parameter value to a test target flow;
measuring the surface flow velocity and the water depth of the thin-layer water flow in the scouring water tank, and further calculating the submergence degree of the thin-layer water flow in the scouring water tank on the ground surface covering objects, and the average flow velocity, Reynolds number and correction coefficient of the thin-layer water flow in the scouring water tank;
and respectively establishing a non-submerged state and submerged state downhill surface thin layer water flow velocity correction coefficient prediction model according to the submergence degree.
2. The method for predicting the slope sheet water flow velocity correction coefficient according to claim 1, wherein the step of laying a surface covering on the bottom of the washing tank to simulate the natural slope covering condition further comprises:
and laying a simulated soil layer at the bottom of the flushing water tank, and laying the ground surface covering object with a set size on the surface of the simulated soil layer according to a set covering proportion Cr.
3. The method of predicting the slope sheet water flow velocity correction factor of claim 1, wherein the step of providing a steady water flow to the wash tank and adjusting the water flow parameter value to a test target flow further comprises:
the flow of the water flow entering the scouring water tank is adjusted to a test target flow Q by adjusting a variable frequency water pump and a ball valve on a connecting pipeline of the water supply water tank and the scouring water tank.
4. The method for predicting the sheet flow velocity correction factor for sloping surface according to claim 1, wherein the step of measuring the surface flow velocity and the water depth of the sheet flow in the erosion water tank, and further calculating the submergence degree of the sheet flow in the erosion water tank on the surface covering, and the average flow velocity, the reynolds number and the correction factor of the sheet flow in the erosion water tank further comprises:
setting a plurality of flow velocity measurement sections along the inclined direction of the flushing water tank, setting intervals between two adjacent flow velocity measurement sections, setting a plurality of flow velocity measurement point positions on each flow velocity measurement section, and repeatedly measuring the thin layer at each flow velocity measurement point position by adopting a dyeing tracing methodCalculating the average value of the flow velocity measurement values of each flow velocity measurement point and each flow velocity measurement section, and further obtaining the surface flow velocity V of the slope laminar flows。
5. The slope sheet water flow velocity correction coefficient prediction method of claim 4, further comprising:
and a plurality of bathymetric sections are arranged along the inclined direction of the scouring water tank, the interval between every two adjacent bathymetric sections is set, each bathymetric section is provided with a plurality of bathymetric point positions, each bathymetric point position adopts a water level probe to repeatedly measure the water depth of the laminar flow, the average value of the bathymetric values of each bathymetric point position and each bathymetric section is calculated, and the water depth h of the slope laminar flow is obtained.
6. The slope sheet water flow velocity correction coefficient prediction method of claim 5, further comprising:
calculating and obtaining the submergence degree Lambda of the water flow in the scour water tank to the surface covering object through the water depth h of the thin-layer water flow and the size value k of the surface covering object,
7. the slope sheet water flow velocity correction coefficient prediction method of claim 4, further comprising:
calculating the calculated value V of the average flow velocity of the slope laminar flow according to the flow value Q and the water depth h of the laminar flowm，
w＝W×(1-Cr)
Wherein w is the effective water flow width; w is the width of the flushing water tank, and Cr is the coating proportion of the ground surface coating.
8. The method of predicting the slope sheet water flow velocity correction coefficient of claim 7, further comprising:
calculating value V according to water depth h and average flow velocity of laminar water flowmCalculating the Reynolds number Re of the slope sheet water flow,
wherein v is the viscosity coefficient of water, t is the temperature of water, and q is the single width flow.
9. The method of predicting the slope sheet water flow velocity correction coefficient according to claim 1, wherein the step of establishing the correction coefficient prediction model according to the inundation degree further comprises:
according to the measured superficial velocity V of the laminar water flowsAnd calculated value V of flow velocitymCalculating a water flow velocity correction coefficient calculation value alpha,
a correction coefficient prediction model is established,
α＝a×logRe+b×logΛ-c×logS+d Λ＜1
α＝a×logRe-b×logΛ-c×logS+d Λ≥1
wherein a, b, c and d are regression prediction model coefficients, and S is the inclination angle of the flushing water tank.
10. The slope surface thin layer water flow velocity correction coefficient prediction device for implementing the slope surface thin layer water flow velocity correction coefficient prediction method according to any one of claims 1 to 9, characterized by comprising a water supply tank, a steady flow water tank and a flushing water tank, wherein the water supply tank is connected with the steady flow water tank through a conveying pipeline, and a variable frequency water pump, an electromagnetic flow meter and a ball valve are sequentially arranged on the conveying pipeline along the flow direction of water flow;
the steady flow water tank is internally provided with a baffle with holes, the baffle with holes divides the steady flow water tank into a first steady flow area and a second steady flow area, the conveying pipeline is connected with the first steady flow area, and the second steady flow area is communicated with the first end of the flushing water tank;
the scouring water tank is arranged on the support frame, the second end of the scouring water tank is hinged to the support frame, the support frame is provided with a hydraulic cylinder, and the output end of the hydraulic cylinder is hinged to the bottom side of the first end of the scouring water tank.
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