A method for quickly predicting the thickness of sediments in a full-flow box culvert in rainy weather

Abstract

The application provides a method for quickly predicting the thickness of sediments in a box culvert in a rain day, which can quickly predict the thickness of sediments in a box culvert in a rain day, save manpower and material resources compared with actual measurement, help support the operation and maintenance management of the box culvert, be beneficial to optimizing the design specification and dredging work of the box culvert, guarantee the flow capacity of the box culvert, reduce the overflow pollution and urban waterlogging risk.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of urban drainage, in particular to a method for quickly predicting the thickness of sediments in a full-flow box culvert in rainy days, which can be used for box culvert optimization reconstruction and operation and maintenance. BACKGROUND

[0002] The current severe challenge faced by urban water environment is combined sewer overflow pollution problem, and the interception of box culvert can reduce the environmental risk caused by combined sewer overflow pollution to a certain extent. The sediments in the box culvert can weaken the flow capacity of the box culvert, and after the box culvert appears large-scale siltation, the risk of urban waterlogging will be greatly increased. The sediments in the box culvert are mainly derived from the particulate pollutants on the urban underlying surface, and the soil sand enters the drainage system through the partially damaged pipes. In the middle and lower reaches of the Yangtze River, due to the problems of relatively abundant rainfall, insufficient interception multiple, and serious siltation, the box culvert often operates in high water level or even full water level in rainy days, and the particulate sediments enter the submerged area with low flow rate to form a sediment layer, and later with the entry of organic matter and viscous substances, a permanent sediment layer can be developed through consolidation. Existing studies have shown that the thickness of sediments in submerged box culverts can reach half of the height of the box culvert, which inevitably aggravates urban waterlogging. Therefore, predicting the thickness of sediments is helpful for formulating reasonable dredging maintenance scheme and providing basis for optimizing the design of box culvert system.

[0003] The existing sediment thickness measurement methods are mainly based on field survey. The field survey includes direct measurement of sediment thickness by manual measurement, device measurement (CN211783204U), laser ranging measurement (CN210242699U), and pipeline robot measurement. At present, there is a lack of a method for quickly predicting the thickness of sediments in a full-flow box culvert in rainy days. SUMMARY

[0004] The technical problem to be solved by the present application is to provide a method for quickly predicting the thickness of sediments in a full-flow box culvert in rainy days, which can quickly predict the thickness of sediments in a full-flow box culvert in rainy days, save manpower and resources compared with actual measurement, help support box culvert operation and maintenance management, be conducive to optimizing the design specification and dredging work of the box culvert, guarantee the flow capacity of the box culvert, and reduce the risk of overflow pollution and urban waterlogging.

[0005] In order to realize the above technical features, the purpose of the present application is realized as follows: a method for quickly predicting the thickness of sediments in a full-flow box culvert in rainy days, comprising the following steps:

[0006] Step one: determining the thickness h of the bottom sediment layer, the wet perimeter Pw of the sediment layer, and the wet perimeter P of the box culvert wall bAnd the over-flow area A, box culvert width W, box culvert height H, wet perimeter mainly represents the sediment layer and the contact of box culvert wall and water flow, also reflects the stress range of shear force generated by water flow, the formula of each parameter is as follows:

[0007] P b = W (1)

[0008] P w = 2(H-h) + W (2)

[0009] A = W(H-h) (3)

[0010] Step two: determine the flow velocity V in the rain day full-flow box culvert, wherein the flow is the design flow Q of the rain day box culvert s , mainly according to the properties of catchment area, town type, climate characteristics to determine the design return period and rainfall duration to determine the design flow, the design flow is determined by formula (4):

[0011] Q s = qψF (4)

[0012] V = Q / A (5)

[0013] Wherein: q is the design storm intensity, ψ is the comprehensive runoff coefficient, F is the catchment area;

[0014] Step three: determine the comprehensive hydraulic radius R c , the comprehensive hydraulic radius is determined by the over-flow area, the wet perimeter of the sediment layer and the wet perimeter of the box culvert wall:

[0015] R c = A / (P w +P b ) (6)

[0016] Step four: determine the Reynolds number R e in the rain day full-flow box culvert:

[0017] R e = 4VR c / v (7)

[0018] Wherein: v is the kinematic viscosity coefficient;

[0019] Step five: the Colebrook formula is used to calculate the friction coefficient f of the sediment layer of the square cross-section box culvert s , in order to realize fast calculation, the Colebrook formula is used:

[0020] f s = 1.163[ln(0.234e 1.1007 -60.525 / Re 1.1105 + 56.291 / Re 1.0712 )]-2 (8)

[0021] where: e is the relative roughness coefficient, i.e. the median grain size d 50 of the sediment layer to the height of the box culvert;

[0022] Step six: determine the corrected friction coefficient f b after the sediment is carried by the water flow, more kinetic energy is needed to be consumed, and the corrected sediment-carrying friction coefficient is twice the friction coefficient of the sediment layer:

[0023] f b = 2f s (9)

[0024] Step seven: determine the shear stress τ b of the sediment layer, which is mainly determined by the sediment-carrying friction coefficient and the flow velocity in the box culvert:

[0025] τ b = (f b ρV 2 ) / 8 (10)

[0026] where: ρ is the density of water;

[0027] Step eight: determine the sediment transport rate q s per unit width, i.e. the mass of sediment transported above the sediment layer per unit width per unit time:

[0028] q s = CQ / P b (11)

[0029] where: C is the concentration of sediment in the full-flowing box culvert;

[0030] Step nine: determine the dimensionless particle size D* of the sediment:

[0031] D* = d 50 ((s-1)g / ν 2 ) (1 / 3) (12)

[0032] where: s is the relative density of the sediment, and g is the acceleration of gravity;

[0033] Step ten: determine the critical shear force τ c of the particles:

[0034] τ c = θ c (s-1)d 50 ρg (13)

[0035] where: θ c is obtained from the dimensionless particle size;

[0036] Step eleven: determine the shear strength T:

[0037] T = (τ b -τ c ) / τ c (14)

[0038] Step twelve: determine the sediment jump length λ:

[0039] λ = 2.4d 50 D* 0.27 T 1.5 (15)

[0040] Step thirteen: determine the sediment erosion rate E:

[0041] E = q s / λ (16)

[0042] Step fourteen: determine the dimensionless transport parameter φ:

[0043] φ = E / (ρ s ((s-1)gd 50 ) 0.5 ) (17)

[0044] Wherein: ρ s is the density of the sediment;

[0045] Step fifteen: determine the dimensionless bottom shear stress θ b :

[0046] θ b = 17.54φ 1 / (0.97+0.2Y) + 0.03 + 0.06Y (18)

[0047] Wherein: Y is the mass fraction of the sediment layer occupied by viscous substances;

[0048] Step sixteen: another expression of the sediment layer shear stress τ b :

[0049] τ b = θ b (s-1)d 50 ρg (19)

[0050] Step seventeen: only the sediment thickness is an unknown parameter in the above formula, by simultaneously solving formula (10) and (19), using the single variable solving tool of Excel to solve the sediment thickness, to achieve the purpose of predicting the sediment thickness in the full-flow box culvert in rainy days.

[0051] In the process of determining the bottom sediment layer thickness h in the step one, it is assumed that the sediment layer is isohypse in the box culvert section; and it is assumed that the sediment layer width is equal to the box culvert width.

[0052] Also includes step eight: list the thickness of the sediment case matrix under different conditions, and give relevant suggestions for box culvert design and sediment dredging maintenance.

[0053] Typical conditions include:

[0054] 1) sediment median particle size d 50 = 0.4, 0.9, 1.8, 2.5mm;

[0055] 2) mass fraction of viscous material Y = 0, 0.1, 0.2, 0.4;

[0056] 3) P = 1, 2 years because most of the existing design recurrence period is less than two years;

[0057] 4) medium city rainfall duration t = 90, 120min.

[0058] The present application has the following beneficial effects:

[0059] 1) The present application can quickly predict the thickness of the sediment in the full-flow box culvert in rainy days, which can save manpower and material resources compared with actual measurement, help support box culvert operation and maintenance management, be conducive to optimizing the design specification and dredging work of the box culvert, and protect the flow capacity of the box culvert, reduce the risk of overflow pollution and urban waterlogging.

[0060] 2) The present application uses dimensionless bottom shear stress and shear stress calculated by kinetic friction coefficient to solve the thickness of the sediment. In actual operation, the thickness of the sediment can be directly measured by underwater operation or pipeline robot. Such method needs complicated preliminary preparation work to lower the downstream water level to directly measure. The pipeline robot has insufficient obstacle avoidance ability, and there may be a large amount of toxic gas in the box culvert, so manual measurement method has high risk. And at the end of pumping and lowering water level, the thickness of the sediment layer may change due to the disturbance of water flow, thereby underestimating the real thickness of the sediment layer and the operation and maintenance frequency of the box culvert. BRIEF DESCRIPTION OF DRAWINGS

[0061] The present application will be further described below in conjunction with the drawings and examples.

[0062] Figure 1 The flowchart of the present application.

[0063] Figure 2 The box culvert sediment diagram.

[0064] Figure 3 The Hill-Curtis curve.

[0065] Figure 4 The thickness of the sediment case matrix of the full-flow box culvert in rainy days. DETAILED DESCRIPTION

[0066] The embodiments of the present application will be further described below with reference to the drawings.

[0067] Example 1

[0068] Referring to Figures 1-4 A method for quickly predicting the thickness of sediment in a full-flow box culvert in rainy days includes the following steps:

[0069] Step one: determine the thickness h of the bottom sediment layer, the wet perimeter Pw of the sediment layer, the wet perimeter P of the box culvert wall b and the flow area A, the width W of the box culvert, and the height H of the box culvert. The wet perimeter mainly characterizes the contact between the sediment layer and the box culvert wall and the water flow, and also reflects the range of shear force generated by the water flow. The formulas for calculating each parameter are as follows:

[0070] P b = W (1)

[0071] P w = 2(H-h) + W (2)

[0072] A = W(H-h) (3)

[0073] Step two: determine the flow velocity V in the full-flow box culvert in rainy days, wherein the flow rate is the design flow rate Q of the box culvert in rainy days s . The design flow rate is determined mainly according to the properties of the catchment area, the type of town, and the climate characteristics to determine the design return period and the rainfall duration, and is determined by formula (4):

[0074] Q s = qψF (4)

[0075] V = Q / A (5)

[0076] Wherein: q is the design storm intensity, ψ is the comprehensive runoff coefficient, and F is the catchment area;

[0077] Step three: determine the comprehensive hydraulic radius R c . The comprehensive hydraulic radius is determined by the flow area, the wet perimeter of the sediment layer, and the wet perimeter of the box culvert wall:

[0078] R c = A / (P w + P b ) (6)

[0079] Step four: determine the Reynolds number R e in the full-flow box culvert in rainy days:

[0080] R e = 4VR c / v (7)

[0081] Where: v is the kinematic viscosity coefficient;

[0082] Step five: Colebrook formula is used to calculate the friction coefficient f of the sediment layer of the box culvert with square cross section s In order to realize fast calculation, Colebrook formula is used to show the approximate formula:

[0083] f s = 1.163 [ln (0.234e 1.1007 -60.525 / Re 1.1105 + 56.291 / Re 1.0712 )] -2 (8)

[0084] Where: e is the relative roughness coefficient, that is, the median particle size d 50 of the sediment particles in the sediment layer;

[0094] The ratio of the height of the box culvert;

[0085] Step six: determine the friction coefficient f after the correction of the sediment carrying b Since the water flow carries a certain concentration of sediment movement, more kinetic energy needs to be consumed, and the corrected sediment carrying friction coefficient is twice the friction coefficient of the sediment layer:

[0086] f b = 2f s (9)

[0087] Step seven: determine the shear stress τ of the sediment layer b , which is mainly determined by the sediment carrying friction coefficient and the flow velocity in the box culvert:

[0088] τ b = (f b ρV 2 ) / 8 (10)

[0089] Where: ρ is the density of water;

[0090] Step eight: determine the sediment transport rate q per unit width s , that is, the sediment mass transported above the sediment layer per unit width per unit time:

[0091] q s = CQ / P b (11)

[0092] Where: C is the concentration of sediment in the full-flow box culvert;

[0093] Step nine: determine the dimensionless particle size D* of the sediment:

[0094] D* = d 50 ((s-1)g / ν 2 ) (1 / 3) (12)

[0095] where s is the relative density of the sediment, and g is the acceleration of gravity;

[0096] Step ten: Determine the critical shear stress of the particle τ c :

[0097] τ c = θ c (s-1)d 50 ρg (13)

[0098] where θ c is obtained from the dimensionless particle size;

[0099] Step eleven: Determine the shear stress intensity T:

[0100] T = (τ b - τ c ) / τ c (14)

[0101] Step twelve: Determine the sediment jump length λ:

[0102] λ = 2.4d 50 D* 0.27 T 1.5 (15)

[0103] Step thirteen: Determine the sediment erosion rate E:

[0104] E = q s / λ (16)

[0105] Step fourteen: Determine the dimensionless transport parameter φ:

[0106] φ = E / (ρ s ((s-1)gd 50 ) 0.5 ) (17)

[0107] where ρ s is the density of the sediment;

[0108] Step fifteen: Determine the dimensionless bottom shear stress θ b :

[0109] θ b = 17.54φ 1 / (0.97+0.2Y) + 0.03 + 0.06Y (18)

[0110] where Y is the mass fraction of the viscous substance in the sediment layer;

[0111] Step sixteen: Another expression of the shear stress τ b of the sediment layer:

[0112] τb = θ b (s-1)d 50 pg (19)

[0113] Step seventeen: only the thickness of the sediment is unknown in the above formula, by simultaneously solving formula (10) and (19), using the single variable solving tool of Excel to solve the thickness of the sediment, so as to achieve the purpose of predicting the thickness of the sediment in the full-flow box culvert in rainy days;

[0114] Step eighteen: list the sediment thickness case matrix under different working conditions, and give relevant suggestions for the design of the box culvert and the maintenance of the sediment dredging.

[0115] Further, in the process of determining the thickness h of the bottom sediment layer in step one, it is assumed that the sediment layer is contour in the cross section of the box culvert; and it is assumed that the width of the sediment layer is equal to the width of the box culvert.

[0116] Typical working conditions include:

[0117] 4) the median particle size d of the sediment 50 = 0.4, 0.9, 1.8, 2.5 mm;

[0118] 5) the mass fraction Y of the viscous substance = 0, 0.1, 0.2, 0.4;

[0119] 6) P = 1, 2 years because most of the existing design return periods are less than two years;

[0120] 4) the rainfall duration t of the medium-sized city = 90, 120 min.

[0121] Example 2:

[0122] The present application provides a method for predicting the thickness of the sediment in a submerged rainwater discharge outlet, and the specific implementation steps are as follows:

[0123] (1) the width of the box culvert is 2 m, and the height is 1.5 m. The expression of the wet perimeter P of the sediment layer w , the wet perimeter P of the box culvert b and the flow area A are respectively: P w = 5-2h (m); P b = 2 (m); A = 3-2h (m 2 ).

[0124] (2) mainly according to the catchment area 44h (m 2 ), the comprehensive runoff coefficient of the urban underlying surface is 0.60, the design return period is 2 years according to the Outdoor Drainage Design Standard, the rainfall duration is 120 minutes, and the corresponding rainfall intensity is 86.2 L / (hm 2• s), the design flow rate is determined to be 2.28 m / s according to equation (4) 3 / s. The design flow rate is determined to be

[0125] V = 2.28 / (3 - 2h) (m / s).

[0126] (3) Determine the comprehensive hydraulic radius R c . R c = (3 - 2h) / (7 - 2h) (m).

[0127] (4) Determine the Reynolds number R e in the full-flow box culvert, v = 1.00 x 10 -6 . R e = 9.12 x 10 6 / (7 - 2h).

[0128] (5) Determine the friction coefficient f s of the sediment layer, e = d 50 / H = 0.0018 / 1.5 = 0.0012, f s = 1.163 [ln(0.00014 - 60.525 / (9.12 x 10 6 / (7 - 2h)) 1.1105 + 56.291 / (9.12 x 10 6 / (7 - 2h)) 1.0712 )] -2 .

[0129] (6) f b = 2.326 [ln(0.00014 - 60.525 / (9.12 x 10 6 / (7 - 2h)) 1.1105 + 56.291 / (9.12 x 10 6 / (7 - 2h)) 1.0712 )] -2 .

[0130] (7) Determine the shear stress τ b of the sediment layer, mainly determined by the sediment carrying friction coefficient and the flow rate in the box culvert:

[0131] τ b = 1511 [ln(0.00014 - 60.525 / (9.12 x 10 6 / (7 - 2h)) 1.1105 + 56.291 / (9.12 x 10 6 / (7 - 2h)) 1.0712 )] -2 / (3 - 2h) 2 .

[0132] (8) Determine the single-width sediment transport rate q s , C = 0.2 kg / m 3 , qs= 0.228 kg / m / s.

[0133] (9) Determine the dimensionless grain size of the sediment D*, D* = 45.26.

[0134] (10) Determine the critical shear stress of the grain τ c , θ c = 0.04, τ c = 1.16 N / m 2 .

[0135] (11) Determine the shear stress intensity T, T = (1511 [ln(0.00014 - 60.525 / (9.12 x 10 6 / (7 - 2h)) 1.1105 + 56.2

[0136] 91 / (9.12 x 10 6 / (7 - 2h)) 1.0712 )] -2 / (3 - 2h) 2 - 1.16) / 1.16.

[0137] (12) Determine the sediment saltation length λ, λ = 0.012((1511 [ln(0.00014 - 60.525 / (9.12 x 10 6 / (7 - 2h)) 1.1105 + 56.2 6 91 / (9.12 x 10 1.0712 / (7 - 2h)) -2 )] 2 / (3 - 2h) 1.5 - 1.16) / 1.16).

[0138] (13) Determine the sediment erosion rate E, E = 19 / ((1511 [ln(0.00014 - 60.525 / (9.12 x 10 6 / (7 - 2h)) 1.1105 + 56.2 6 91 / (9.12 x 10 1.0712 / (7 - 2h)) -2 )] 2 / (3 - 2h) 1.5 - 1.16) / 1.16).

[0139] (14) Determine the dimensionless transport parameter φ, φ = 0.042 / ((1511 [ln(0.00014 - 60.525 / (9.12 x 106 (7 - 2h) 1.1105 + 56.291 / (9.12 x 10 6 (7 - 2h) 1.0712 ] -2 (3 - 2h) 2 - 1.16) / 1.16) 1.5 .

[0140] (15) Dimensionless bottom shear stress θ b , Y = 0, θ b = 17.54(0.042 / ((5 - 2h)((1511[ln(0.00014 - 60.525 / (9.12 x 10 6 (7 - 2h) 1.1105 + 56.291 / (9.12 x 10 6 (7 - 2h) 1.0712 ] -2 (3 - 2h) 2 - 1.16) / 1.16) 1.5 ) 1.031 + 0.03.

[0141] (16) Sediment layer shear stress τ b , τ b = 29.106(17.54(0.042 / ((5 - 2h)((1511[ln(0.00014 - 60.525 / (9.12 x 10 6 (7 - 2h) 1.1105 + 56.291 / (9.12 x 10 6 (7 - 2h) 1.0712 ] -2 (3 - 2h) 2 - 1.16) / 1.16) 1.5 ) 1.031 + 0.03.

[0142] (17) The two sediment layer shear stress calculation formulas are combined, and the sediment thickness h = 0.481 m can be solved, which accounts for 32.07% of the box culvert height.

[0143] (18) The sediment thickness case matrix of the full-flow box culvert under rain in the remaining working conditions is shown in Figure 4 . With the increase of sediment particle size, the sediment layer thickness gradually increases, and the influence of the mass fraction of viscous substances on the sediment thickness is relatively small. The sediment thickness inside the box culvert with a design return period of one year is large, and the maximum can reach 50% of the depth of the box culvert. The longer the rainfall duration of the box culvert, the greater the sediment thickness.

[0144] Based on the analysis of working conditions, the suggestions for the design of box culverts include: 1) the design return period is 2 years, and the old box culverts with a design return period less than 2 years need to be reconstructed; 2) the design rainfall duration of box culverts should not be too long, and generally 90 min is taken, and the thickness of the sediment layer can be controlled within 20% of the height of the box culvert.

[0145] The suggestions for dredging maintenance include: 1) setting up sand removal devices at the source of the pipe network to reduce the entry of particles with a particle size exceeding 0.9 mm into the pipe network system; 2) increasing the dredging frequency for box culverts with a design return period less than 2 years to reduce the risk of waterlogging.

Claims

1. A method for quickly predicting the thickness of sediment in a full-flow box culvert during rain, characterized by, Comprising the following steps: Step one: determine the thickness of the bottom sediment layer h, the wet perimeter of the sediment layer Pw, the wet perimeter of the box culvert wall P b And the flow area A, the box culvert width W, the box culvert height H, the wet perimeter mainly characterizes the contact between the sediment layer and the box culvert wall and the water flow, and also reflects the stress range of the shear force generated by the water flow. The calculation formula of each parameter is as follows: P b = W (1) P w = 2(H - h) + W (2) A = W(H-h) (3) Step two: determine the flow rate V in the full-flow box culvert on rainy days, where the flow is the design flow Q of the box culvert on rainy days s The design flow is determined according to the catchment area properties, the town type, and the climate characteristics to determine the design recurrence period and the rainfall duration, and the design flow is determined by formula (4): Q s = qψF (4) V = Q / A (5) Where: q is the design storm intensity, ψ is the comprehensive runoff coefficient, F is the catchment area; Q is the flow in the box culvert; Step three: determine the comprehensive hydraulic radius R c The comprehensive hydraulic radius is determined by the flow area, the wet perimeter of the sediment layer, and the wet perimeter of the box culvert wall. R c = A / (P w + P b ) (6) Step four: Determine the Reynolds number R in the full-flow box culvert on rainy days e : R e = 4VR c / v (7) Where: v is the kinematic viscosity coefficient; Step five: Colebrook equation is used to calculate the friction factor f of the sediment layer of the box culvert with square cross section s To achieve fast calculation, the Colebrook equation is used f s = 1.163 [ln(0.234e 1.1007 - 60.525 / Re 1.1105 + 56.291 / Re 1.0712 )] -2 (8) wherein: e is the relative roughness factor, i.e. the median particle size d 50 Ratio of culvert height to height of flow Step six: Determine the corrected friction factor f with sediment b Since the water flow carries a certain concentration of sediment movement, it needs to consume more kinetic energy, and the corrected sediment friction factor is twice the friction factor of the sediment layer: f b = 2f s (9) Step seven: Determine the shear stress τ of the deposited layer b which is mainly determined by the sediment carrying friction factor and the flow velocity in the box culvert: τ b = (f b ρV 2 ) / 8 (10) Where: ρ is the density of water; Step eight: Determine the single-width sediment transport rate q s i.e. the mass of sediment transported above the deposited layer per unit width per unit time: q s = CQ / P b (11) Where: C is the concentration of sediment in the full-flow box culvert; Step nine: determine the dimensionless particle size of sediment D*: D* = d 50 ((s-1)g / ν 2 ) (1 / 3) (12) Where: s is the relative density of sediment, g is the acceleration of gravity; Step ten: Determining the critical shear force τ of the particles c : τ c = θ c (s-1)d 50 pg (13) where: θ c is obtained from the dimensionless particle size Step eleven: determine the shear strength T: T = (τ b -τ c ) / τ c (14) Step twelve: determine the sediment jump length λ: λ = 2.4d 50 D* 0.27 T 1.5 (15) Step thirteen: determine the sediment erosion rate E: E = q s / λ (16) Step fourteen: determine the dimensionless transport parameter φ: φ = E / (p s ((s-1)gd 50 ) 0.5 ) (17) where: p s is the density of the deposit; Step fifteen: Determining the dimensionless bottom shear stress θ b : θ b = 17.54 φ 1 / (0.97+0.2Y) + 0.03 + 0.06 Y (18) Where: Y is the mass fraction of viscous material in the sediment layer; Step sixteen: Deposition layer shear stress τ b Another way of expressing this is: τ b = θ b (s-1)d 50 pg (19) Step seventeen: only the sediment thickness is an unknown parameter in the above formula, by simultaneously solving formula (10) and (19), using the single variable solving tool of Excel to solve the sediment thickness, to achieve the purpose of predicting the sediment thickness in the full-flow box culvert in rainy days.

2. The method for quick prediction of the thickness of the deposits in the full-flow box culvert in the rainy weather according to claim 1, characterized by the fact that In the process of determining the bottom sediment layer thickness h in step one, it is assumed that the sediment layer is isohypse in the box culvert cross section; and it is assumed that the sediment layer width is equal to the box culvert width.

3. The method for quick prediction of the thickness of the sediment in the full-flow box culvert in the rainy day according to claim 1, characterized in that, It also includes step eighteen: listing the sediment thickness case matrix under different working conditions, and giving relevant suggestions for box culvert design and sediment dredging maintenance.

4. The method for quick prediction of the thickness of the deposits in the full-flow box culvert in the rainy weather according to claim 1, characterized by the fact that Typical working conditions include: 1) Median particle size dso of the deposit 50 = 0.4, 0.9, 1.8, 2.5 mm; 2) The mass fraction of viscous material Y = 0, 0.1, 0.2, 0.4; 3) P = 1, 2 years because most of the existing design return periods are less than two years; 4) The rainfall duration t = 90, 120 min in medium-sized cities.

Images