CN115901159A - Pneumatic sand-washing dredging effect prediction method - Google Patents

Pneumatic sand-washing dredging effect prediction method Download PDF

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CN115901159A
CN115901159A CN202310221269.1A CN202310221269A CN115901159A CN 115901159 A CN115901159 A CN 115901159A CN 202310221269 A CN202310221269 A CN 202310221269A CN 115901159 A CN115901159 A CN 115901159A
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test
pit
factors
sand
washing
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杨啸宇
沈南北
王逸飞
丁磊
缴健
窦希萍
罗勇
陈犇
孙洁莹
陈书宁
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Nanjing Hydraulic Research Institute of National Energy Administration Ministry of Transport Ministry of Water Resources
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Nanjing Hydraulic Research Institute of National Energy Administration Ministry of Transport Ministry of Water Resources
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Abstract

The invention discloses a method for predicting pneumatic sand-washing desilting effect, which belongs to the technical field of jet flow sand-washing, and comprises the following steps: measuring the turbulent fluctuation intensity of the water body, and analyzing the flow velocity of a measuring point of a section; determining test factors and parameter ranges of the factors to carry out combined test; recording test factors and parameter ranges, and measuring the maximum depth of the erosion pit and the volume parameter of the erosion pit; the test data is analyzed, the correlation between the maximum depth of the erosion pit, the volume of the erosion pit and each test factor is determined, and the pneumatic sand-washing desilting effect prediction method has the advantages of quantifying the sand-washing effect and predicting the sand-washing capability. In the application of actual engineering, the proposal of the optimal erosion and deposition effect scheme can be guided and the erosion and deposition condition can be predicted.

Description

Pneumatic sand-washing dredging effect prediction method
Technical Field
The invention belongs to the technical field of jet flow scouring and dredging, and particularly relates to a pneumatic sand scouring and dredging effect prediction method.
Background
The problem of local sediment accumulation of the main tanks of rivers, reservoirs, water gates, lakes and rivers is ubiquitous, huge adverse effects are brought, students at home and abroad make extensive research aiming at the problem of local sediment accumulation of the sediment, a series of application technologies are formed, the cost of the traditional mechanical sediment removal measures is high, the application range is limited, and the conventional water drainage and sand flushing problem is low in efficiency.
At present, the problem of local siltation generally exists, a plurality of defects exist in a traditional desilting mode, if the desilting mode is applied to a project blindly, the cost is increased, the desilting effect is difficult to guarantee, and the optimal sand flushing effect and the optimal predicted sand flushing capability can not be realized by judging and obtaining what kind of factors before desilting, so that the existing problem needs to be solved by researching and developing a pneumatic sand flushing desilting effect prediction method.
Disclosure of Invention
The invention aims to provide a pneumatic sand-washing desilting effect prediction method to solve the problem that the optimal sand-washing effect and the optimal sand-washing capability cannot be realized by judging which factors in pneumatic sand-washing.
In order to achieve the purpose, the invention provides the following technical scheme: a method for predicting pneumatic sand-washing dredging effect; the method comprises the following steps:
measuring the flow velocity of a measuring point of the section, and analyzing the turbulent fluctuation intensity of the water body;
determining test factors and test factor parameter ranges, and performing a combined test;
recording parameters of measurement test factors, the maximum depth of the scour pit and the volume parameters of the scour pit to form test data;
and analyzing the test data to obtain a prediction equation between the maximum depth of the erosion pit and the volume of the erosion pit and the test factors.
Preferably, before analyzing the turbulent fluctuation intensity of the water body, a test water tank needs to be established, a pneumatic sand washing device is arranged, prototype sand or model sand with the same compactness degree is paved in the test water tank, and the gas spraying direction is the central position of a sand washing area.
Preferably, the test factors include: the distance A from the air nozzle to the bottom of the tank is the difference between the nozzle elevation and the bed sand surface elevation, and when the air nozzle extends into the bed sand, the distance from the nozzle to the bottom of the tank is a negative value.
Preferably, the method for analyzing the water body turbulence intensity comprises the following steps: setting the sampling frequency to be 25Hz and the single-point measurement time to be 45s; calculating the acquired time sequence data to respectively obtain the horizontal time-average flow rate
Figure SMS_2
Vertical time-average flow velocity
Figure SMS_6
And a horizontal time-averaged flow rate->
Figure SMS_9
Corresponding pulsating flow rate->
Figure SMS_1
The mean flow velocity in the vertical direction>
Figure SMS_5
Corresponding pulsating flow velocity
Figure SMS_8
Based on the pulsating flow rate>
Figure SMS_11
Is root mean square->
Figure SMS_3
Representing the intensity of the turbulence by the water body density and the pulsating flow velocity>
Figure SMS_4
、/>
Figure SMS_7
Negative value of a second order moment of correlation product>
Figure SMS_10
Representing the turbulent shear stress, setting the power to be the same as the gravity, setting the gravity acceleration borne by the water flow in the water tank model to be the same as the gravity acceleration borne by the prototype water flow, and setting the pressure scale to be equal to the length scale to obtain the following components:
Figure SMS_12
in the formula (II)>
Figure SMS_13
Is a time scale, in combination with a plurality of light sources>
Figure SMS_14
Is a pressure scale.
Preferably, the measuring the maximum depth of the erosion pit comprises: measuring the maximum depth of the scour pit by means of a measurement apparatus comprising: the device comprises a connecting mechanism, a sliding chute, an adjusting mechanism and a measuring pin; the connecting mechanism is erected above the water tank and is vertical to the ground; the sliding grooves comprise an upper sliding groove and a lower sliding groove, the lower sliding groove is installed on the connecting mechanism, the upper sliding groove is installed above the lower sliding groove, a first sliding block is arranged between the upper sliding groove and the lower sliding groove to enable the upper sliding groove to slide along the upstream direction and the downstream direction of the lower sliding groove, and the upper sliding groove is provided with a hand-screwing structure; the adjusting mechanism is arranged on the upper chute, and the adjusting mechanism and the upper chute are provided with second sliding blocks to enable the adjusting mechanism to vertically slide up and down along the upper chute; and the adjusting mechanism is connected with the measuring pin and the reading ruler, and the height of the measuring pin can be manually adjusted.
Preferably, the pneumatic sand flushing device comprises: an air compressor and an exhaust device.
Preferably, the combination test of the parameter ranges of the determining factor and the testing factor comprises: and selecting parameters of the test factors and the test factors by adopting an orthogonal test method to perform a combined test, analyzing the influence of the test factors on the maximum depth and the volume of the scoured pit in the pneumatic sand-washing muddy water test, and mixing the orthogonal test design and the test result.
Preferably, analyzing the test data comprises analyzing the test data using an analysis of variance method, the sources of the test data comprising: the method comprises the steps of determining the ratio of the difference between groups to the difference in groups to a distribution critical value F, wherein the difference between the groups is larger than the difference between the groups due to the difference of experimental conditions between different groups, determining the influence of the experimental conditions by using a water depth P value if the value of F is larger than 1, and determining the factor to be obvious if the value of P is smaller than 0.05.
Preferably, said deriving a prediction between the maximum depth of the erosion pit and the volume of the erosion pit and various factors comprises:
setting the maximum depth of the scour pit asH max The volume of the scour pit isVObtaining the maximum depth of the scoured pit by using polynomial regression and variance analysisH max And the volume of the washout pitVThe regression equation of (a) is shown as follows:
Figure SMS_15
Figure SMS_16
and predicting the maximum depth and the volume of the scoured pit through a regression equation, comparing the maximum depth and the volume with the actual test values under different water and gas parameters, and obtaining a relative deviation value as the ratio of the difference value between the actual test value and the predicted value to the actual test value.
The invention has the technical effects and advantages that: according to the pneumatic sand-washing desilting effect prediction method, through an indoor water tank test, main parameters influencing the sand-washing desilting effect are selected, the sand-washing effect is quantized, the sand-washing capability is predicted, and the method can be efficiently applied to engineering; in the study of the turbulence characteristics of the local water body at the nozzle, the fact that the turbulence intensity of the section is increased along with the increase of the pressure intensity, strong water flow turbulence close to the bottom is formed at the bottom of the impact tank, the bottom turbulence shear stress is rapidly attenuated along with the increase of the distance is obtained, and in a muddy water test, the first 8min of air exhaust is the high-efficiency time interval of scouring; the air pressure and the distance are found to be significant factors for determining the sand washing effect through the analysis of variance in the orthogonal test; a prediction formula of the maximum depth and the volume of the erosion pit is fitted by utilizing polynomial regression, a predicted value is matched with an actually measured value, the problems that the optimal sand flushing effect and the optimal erosion and deposition predicting capacity cannot be achieved by judging and obtaining what factors are solved, the turbulent fluctuation strength of the water body is analyzed by measuring the flow velocity of a measuring point of the section, and the prediction accuracy is improved.
Drawings
FIG. 1 is a schematic flow diagram of the present invention;
FIG. 2 is a mud gradation curve;
FIG. 3 is a front view of the measuring apparatus;
FIG. 4 is a left side view of the measuring device;
FIG. 5 is a top view of the measurement apparatus;
FIG. 6 is a schematic diagram of various test parameters of pneumatic sand blasting;
FIG. 7 is a graph of maximum depth of a scour pit versus volume as a function of time for a purge.
In the figure: 11. a connecting mechanism; 12. an upper chute; 13. a lower chute; 14. an adjustment mechanism; 15. and (6) measuring the needle.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The invention provides a method for predicting the pneumatic sand-washing desilting effect, which comprises the following steps:
step 1: establishing a test water tank, paving prototype sand with the same compactness in the water tank, wherein the spraying direction of an air nozzle is the center of a sand washing area; in this example, the test water tank had a total length of 15.0m, a width of 0.7m and a depth of 1.5m. The pneumatic sand flushing device consists of an air compressor and exhaust equipment, and the position, the angle and the like of the exhaust equipment can be adjusted according to test requirements. The exhaust pressure of the air compressor is 0.8MPa, and the volume flow is 1.1m 3 The air compressor can adjust air pressure, air quantity and the like according to experimental requirements;
in order to ensure that the compaction degree of the spread sand is the same in each test, the residual silt in the erosion and deposition area is re-stirred after each test measurement is finished, prototype sand soaked in advance is spread, and the same compaction work is carried out to ensure that the compaction degree of the spread sand is the same in each test;
step 2: analyzing the turbulence intensity of the water body, and measuring the flow velocity of a measuring point of a section; measuring the water body turbulence intensity by using ADV (Acoustic Doppler Velocity), wherein the ADV sampling frequency is set to be 25Hz, and the single-point measurement time is about 45s; in order to analyze the flow velocity of the measuring point of the section, the acquired time sequence data is calculated, the sampling frequency is set to be 25Hz, and the single-point measuring time is set to be 45s; calculating the acquired time sequence data to respectively obtain horizontal time average flow rate
Figure SMS_18
The mean flow velocity in the vertical direction>
Figure SMS_21
And a horizontal time-averaged flow rate->
Figure SMS_24
Corresponding pulsating flow rate>
Figure SMS_19
The mean flow velocity in the vertical direction>
Figure SMS_22
Corresponding pulsating flow rate->
Figure SMS_25
Based on the pulsating flow rate>
Figure SMS_27
Is root mean square->
Figure SMS_17
Representing the intensity of the turbulence by the water body density and the pulsating flow velocity>
Figure SMS_20
、/>
Figure SMS_23
Negative value of the product of the second order moment of correlation->
Figure SMS_26
Representing the turbulent shear stress, setting the power to be the same as the gravity, setting the gravity acceleration borne by the water flow in the water tank model to be the same as the gravity acceleration borne by the prototype water flow, and setting the pressure scale to be equal to the length scale to obtain the following components:
Figure SMS_28
in combination with>
Figure SMS_29
Is a time scale and is used for selecting and combining>
Figure SMS_30
The pressure is a pressure scale, the adopted air pressure is larger than that of the basin test in pneumatic sand flushing, and in order to ensure the on-site sand flushing efficiency, the sand flushing time in the on-site test can be converted by combining the sand flushing pit size stabilizing time in the basin test with the formula of the scale;
measuring the washed terrain by using the measuring equipment shown in figures 3-5, wherein the measuring equipment mainly comprises a connecting mechanism 11, a chute, an adjusting mechanism 14 and a measuring pin 15; the connecting mechanism 11 is erected above the water tank, and the whole device is vertical to the ground when the connecting mechanism is arranged; the sliding chutes comprise upper sliding chutes 12 and lower sliding chutes 13, the lower sliding chutes 13 are mounted on the connecting mechanism 11, the upper sliding chutes 12 are mounted on the lower sliding chutes 13, first sliding blocks are arranged between the upper sliding chutes 12 and the lower sliding chutes 13 to enable the upper sliding chutes 12 to slide along the upstream direction and the downstream direction of the lower sliding chutes 13, and the upper sliding chutes 12 are provided with hand-screwing tightening structures; the adjusting mechanism 14 is mounted on the upper chute 12, and the adjusting mechanism 14 and the upper chute 12 are provided with second sliding blocks to enable the adjusting mechanism 14 to vertically slide up and down along the upper chute 12; the reading ruler is connected with the measuring pin 15, and the height of the measuring pin 15 can be manually adjusted; the measuring needle 15 is connected to the adjusting mechanism 14, the length of the measuring needle is about 1.0m, the topography of the scoured pit can be measured, the accuracy reaches within +/-3.0 mm, the maximum depth of the scoured pit is measured by using the measuring needle 15, the scoured depth is measured section by section, a scoured topographic map is generated, the volume of the scoured pit is calculated, and the pneumatic sand scouring effect is evaluated;
and step 3: selecting parameters with factors and test factors according to an orthogonal test method to perform a combined test, wherein in this embodiment, the factors are representative factors, and the representative factors are: the distance A from the air nozzle to the bottom of the tank, the air pressure B, the water depth C, the aperture D and the angle E of the air nozzle; the distance A from the air nozzle to the bottom of the tank is the difference between the elevation of the nozzle and the elevation of the surface of the bed sand, and when the air nozzle extends into the bed sand, the distance from the nozzle to the bottom of the tank is a negative value.
Selecting partial representative factors and levels to carry out orthogonal test, researching the influence of the factors on the maximum depth and the volume of the scoured pit in the pneumatic sand-washing muddy water test, wherein the orthogonal test design and the test result are shown in the table 1:
TABLE 1 orthogonal test design and test results
Figure SMS_31
In order to predict the desilting effect of pneumatic sand washing, a still water tank test under the condition of bed sand is carried out, the influence of each water and gas parameter on the sand washing effect is analyzed, the maximum washing depth of a washing pit and a prediction equation between the volume of the washing pit and each factor are obtained, and the equation is optimized to obtain the level of each factor when the maximum sand washing effect is achieved;
and 4, step 4: analyzing the test data to obtain a prediction equation between the maximum scouring depth and the volume of the scouring pit and each factor; in the embodiment, the prediction equation is a regression equation, and the analysis of the test data in the step 4 adopts an analysis of variance method;
the experimental data in table 2 were analyzed using an analysis of variance approach for significance testing of differences in mean values of two or more samples, which considers that the results obtained under different experimental conditions differ from each other by two basic sources: the method comprises the following steps that firstly, an uncontrollable random factor is also called intra-group difference, and the other is a difference caused by different experimental conditions in research, also called inter-group difference, generally speaking, the difference between groups is far larger than the intra-group difference due to the difference of the experimental conditions among different groups, the ratio of the inter-group difference to the intra-group difference is judged with a distribution critical value F, if the distribution critical value F is larger than 1, the influence of the experimental conditions is remarkable, and meanwhile, if the water depth P value is judged, the factor is more remarkable if the water depth P value is smaller than 0.05;
besides judging which factors obviously influence the sand washing effect, a prediction equation between the maximum depth and volume and each factor is obtained; as shown in tables 2 and 3.
TABLE 2 analysis of maximum depth variance of washout pits
Figure SMS_32
Note: the number of variables which can be freely changed when the degree of freedom in the table is data statistics; adj SS denotes the adjusted sum of squares, which is a measure of the variation of different factors of the model; the Adj MS is used for describing the magnitude of a certain variable in the model by adjusting the mean square; s is used for evaluating the coincidence degree of the model result and the experimental result; r-sq is a decision coefficient or a correlation coefficient and is used for describing the coincidence degree of the prediction result and the experimental result, R-sq (adjustment) is used for comparing the coincidence degree of different quantities of prediction variables, and R-sq (prediction) is used for describing the coincidence degree of the prediction result;
as can be seen from table 2, among the 5 factors of distance, air pressure, water depth, aperture and angle, the F values of air pressure and distance are 382.21 and 188.09, which are both much larger than 1, and the P value is much smaller than 0.05, which indicates that these two factors are significant effects, while the P value of water depth is close to 0.05, which has much smaller influence, but the P values of water depth of aperture and angle are both larger than 0.05, which are not significant factors, especially aperture, and it can be seen that, under the condition of small water depth, the significant factors affecting the maximum depth of the flushing pit are the distance between the exhaust air pressure and the nozzle to the bed surface, and the three factors of water depth, aperture and angle have weaker influence on the depth of the flushing pit.
TABLE 3 washout pit volume analysis of variance results
Figure SMS_33
As can be seen from table 3, also under low water depth conditions, air pressure and distance are significant factors affecting the volume of the washout pit;
fitting and predicting a pneumatic sand washing formula, and defining the maximum depth of a washed pit asH max The volume of the scouring pit isVAnd obtaining a regression equation of the maximum depth and the maximum volume through variance analysis by using polynomial regression, wherein the regression equation is shown as the following formula:
Figure SMS_34
Figure SMS_35
in the formula (I), the compound is shown in the specification,Athe distance from the air nozzle to the bottom of the groove,BIs air pressure,CIs the depth of water,DThe diameter of the air nozzle,EFor the air nozzle angle, as shown in fig. 6, it can be seen from tables 4 and 5 that R-sq, R-sq (adjustment) and R-sq (prediction) of the whole model are all higher than 90%, which indicates that the data and model analysis results are reliable, the maximum depth and volume of sand washing are predicted by using the above formula, and compared with the experimental measured values under different water and gas parameter conditions of sand washing orthogonal design, the relative deviation value is the ratio of the difference value between the measured value and the predicted value to the measured value, as shown in tables 4 and 5;
TABLE 4 analysis of the deviation between the predicted maximum depth of the erosion pit and the test value
Figure SMS_36
TABLE 5 analysis of the deviation between the predicted value and the test value of the volume of the washout pit
Figure SMS_37
As can be seen from tables 4 and 5, the regression equation obtained by the analysis of variance can better fit the maximum depth and volume of the erosion pit in the orthogonal design, can be used for predicting the maximum depth and volume of the erosion pit under different water-gas parameter conditions, and compares the predicted value with the measured value, so that the result is satisfactory;
respectively carrying out pneumatic sand flushing and muddy water tests by utilizing a water tank test, finding that air pressure is the most significant factor for determining the plume undercut length through signal-to-noise ratio analysis of an orthogonal test, and fitting a regression equation of the plume undercut length; in the study on the turbulence characteristics of the local water body at the nozzle, the conclusion that the section turbulence intensity is increased along with the increase of the air jet pressure, strong water flow turbulence near the bottom is formed by the impact of jet flow on the bottom of the tank, and the bottom turbulence shear stress is rapidly attenuated along with the increase of the distance is obtained, and in the muddy water test, the first 8min of air exhaust is the high-efficiency period of scouring; the air pressure and the distance are found to be significant factors for determining the sand washing effect through the analysis of variance in the orthogonal test; and fitting a prediction formula of the maximum depth and the volume of the erosion pit by utilizing polynomial regression, wherein the predicted value is matched with the measured value.
Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that modifications may be made to the embodiments or portions thereof without departing from the spirit and scope of the invention.

Claims (9)

1. A pneumatic sand-washing desilting effect prediction method is characterized by comprising the following steps: the method comprises the following steps:
measuring the flow velocity of a measuring point of the section, and analyzing the turbulent fluctuation intensity of the water body;
determining test factors and parameter ranges of the factors to carry out combined test;
recording parameters of measurement test factors, the maximum depth of the scour pit and the volume parameters of the scour pit to form test data;
and analyzing the test data to obtain a prediction equation between the maximum depth of the erosion pit and the volume of the erosion pit and the test factors.
2. The method for predicting the effect of pneumatic sand washing and dredging according to claim 1, wherein: before analyzing the turbulent fluctuation intensity of the water body, a test water tank is established, a pneumatic sand washing device is arranged, prototype sand or model sand with the same compactness degree is paved in the test water tank, and the gas spraying direction is the central position of a sand washing area.
3. The method for predicting the effect of pneumatic sand washing and dredging according to claim 1, wherein: the test factors include: the distance A from the air nozzle to the bottom of the tank is the difference between the nozzle elevation and the bed sand surface elevation, and when the air nozzle extends into the bed sand, the distance from the nozzle to the bottom of the tank is a negative value.
4. The method for predicting the effect of pneumatic sand washing and dredging according to claim 2, wherein: the method for analyzing the water body turbulence intensity comprises the following steps:
setting the sampling frequency to be 25Hz and the single-point measurement time to be 45s; calculating the acquired time sequence data to respectively obtain horizontal time average flow rate
Figure QLYQS_2
And a vertical time mean flow velocity>
Figure QLYQS_4
And a horizontal time-averaged flow rate->
Figure QLYQS_7
Corresponding pulsating flow velocity
Figure QLYQS_3
The mean flow velocity in the vertical direction>
Figure QLYQS_6
Corresponding pulsating flow rate->
Figure QLYQS_9
By pulsating flow rate>
Figure QLYQS_11
Is root mean square->
Figure QLYQS_1
Indicating the intensity of the turbulence in the water volume by the intensity of the water and the pulsating flow velocity>
Figure QLYQS_5
、/>
Figure QLYQS_8
Negative value of a second order moment of correlation product>
Figure QLYQS_10
Expressing the turbulent shear stress, setting the power to be the same as the gravity, setting the gravity acceleration borne by the water flow in the water tank model to be the same as the gravity acceleration borne by the prototype water flow, and setting a pressure scale to be equal to a length scale to obtain:
Figure QLYQS_12
in combination with>
Figure QLYQS_13
Is a time scale and is used for selecting and combining>
Figure QLYQS_14
Is a pressure scale.
5. The method for predicting the effect of pneumatic sand washing and dredging according to claim 1, wherein: measuring the maximum depth of the scour pit by means of a measurement apparatus comprising: the device comprises a connecting mechanism (11), a sliding chute, an adjusting mechanism (14) and a measuring pin (15); the connecting mechanism (11) is erected above the water tank and is vertical to the ground; the sliding grooves comprise an upper sliding groove (12) and a lower sliding groove (13), the lower sliding groove (13) is installed on the connecting mechanism (11), the upper sliding groove (12) is installed on the lower sliding groove (13), a first sliding block is arranged between the upper sliding groove (12) and the lower sliding groove (13) to enable the upper sliding groove (12) to slide along the upstream and downstream directions of the lower sliding groove (13), and the upper sliding groove (12) is provided with a hand screwing structure; the adjusting mechanism (14) is arranged on the upper chute (12), and the adjusting mechanism (14) and the upper chute (12) are provided with second sliding blocks to enable the adjusting mechanism (14) to vertically slide up and down along the upper chute (12); and the adjusting mechanism (14) is connected with the measuring pin (15) and the reading ruler, and the height of the measuring pin (15) can be manually adjusted.
6. The method for predicting the effect of pneumatic sand washing and dredging according to claim 2, wherein: the pneumatic sand flushing device comprises an air compressor and an exhaust device.
7. The method for predicting the effect of pneumatic sand washing and dredging according to claim 1, wherein: the step of determining the test factors and the parameter ranges of the test factors to carry out the combined test comprises the following steps: and selecting parameters of test factors and test factors by adopting an orthogonal test method to perform a combined test, analyzing the influence of the test factors on the maximum depth and the volume of the scoured pit in the pneumatic sand-washing muddy water test, and mixing the orthogonal test design and the test result.
8. The method for predicting the effect of pneumatic sand washing and dredging according to claim 1, wherein: analyzing the test data comprises analyzing the test data using ANOVA, wherein the sources of the test data comprise: the method comprises the following steps of determining the ratio of the difference between groups to the difference in groups to a distribution critical value F, wherein the difference between the groups is larger than the difference between the groups due to the difference of experimental conditions between different groups, determining the influence of the experimental conditions by using a water depth P value if the value of F is larger than 1, and indicating that the factors are obvious if the value of P is smaller than 0.05.
9. The method for predicting the effect of pneumatic sand washing and dredging according to claim 3, wherein: the prediction equation for obtaining the maximum depth of the erosion pit and the volume of the erosion pit and the test factors comprises the following steps:
setting the maximum depth of the scour pit asH max The volume of the scour pit isVObtaining the maximum depth of the scoured pit by using polynomial regression and variance analysisH max And the volume of the washout pitVThe regression equation of (a) is shown as follows:
Figure QLYQS_15
Figure QLYQS_16
and predicting the maximum depth and the volume of the scoured pit through a regression equation, comparing the maximum depth and the volume with the actual test values under different water and gas parameter conditions, and determining the relative deviation value as the ratio of the difference value between the actual test value and the predicted value to the actual test value. />
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