A simulation device for a water-accumulated road surface in rainy days and a driving risk assessment method

Abstract

The present application relates to the field of road test equipment and traffic safety, in particular to a rainwater accumulated road surface simulation device and a driving risk assessment method. The device can better simulate the accumulated water state of the road surface in rainy days. The method combines test and model regression, systematically studies the road section water depth under the coupling action of multiple factors such as slope, rainfall intensity, drainage intensity and time, reduces the influence of natural rainfall uncertainty, and accordingly proposes a water depth estimation model and a driving risk degree index, which helps to correctly guide the road drainage design and maintenance, and also helps to provide reasonable road surface adhesion parameter support for the future driving of unmanned vehicles in rainy days.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of road test equipment and traffic safety, in particular to a rainwater accumulated road surface simulation device and driving risk assessment method. BACKGROUND

[0002] Highway transportation plays a fundamental role in economic development, but rain motor vehicle traffic accidents are still common, and the scientific guidance of existing drivers and road maintenance departments still needs to be improved.

[0003] Road engineering research shows that the influencing factors of rain traffic accidents are mainly accumulated water, poor slope and poor road surface properties. Accumulated water is regarded as an unfavorable lubricating medium in the tire-pavement tribology system, which causes the adhesion properties of tire-pavement to attenuate and generates lifting force that makes the vehicle float and slip, which seriously reduces the vehicle handling performance and driving safety. Investigations show that the position of accumulated water on the road section is mostly at the super-elevation transition section and other continuous change of gentle slope and poor drainage, so it is an important task in the field of road engineering and traffic safety to explore the accumulated water depth distribution law of the road section under rainfall and multi-directional slope and propose targeted measures.

[0004] Existing researches mostly explore the accumulated water state of rain road surface through empirical summary and numerical simulation method, which cannot accurately reflect the accumulated water state of rain road surface. SUMMARY

[0005] In view of the problems existing in the prior art, the purpose of the present application is to provide a rainwater accumulated road surface simulation device and driving risk assessment method.

[0006] In order to achieve the above purpose, the following technical scheme is adopted.

[0007] A rainwater accumulated road surface simulation device, comprising a support plate, a plurality of first through holes are arranged on the support plate, a support rod penetrating through each first through hole is arranged in each first through hole, a thread is arranged on the support rod, a nut matched with the thread is sleeved on the support rod, and the nut is located below the support plate; a foot plate is arranged at the lower end of the support rod;

[0008] A simulation box is arranged on the support plate, a simulation road surface layer is arranged on the bottom plate of the simulation box, the area of the simulation road surface layer is smaller than the area of the bottom plate of the simulation box, and a sealing ring with a notch is arranged between the edge of the simulation road surface layer and the side wall of the simulation box; a first drainage port is arranged at the lower part of one side wall of the simulation box, and the position of the notch of the sealing ring corresponds to the first drainage port;

[0009] Further comprising a sediment tank, a first water inlet is arranged on the top plate of the sediment tank, the first water inlet is connected with the first drainage port through a first drainage pipe, and a second drainage port is arranged at the upper part of one side wall of the sediment tank.

[0010] The water pumping tank is provided with a second water inlet at the upper part of one side wall, the second water inlet is connected with the second water outlet through a second drain pipe; a water pumping pump is arranged on the bottom plate of the water pumping tank, a water outlet of the water pumping pump is connected with a water pumping pipe, and the other end of the water pumping pipe is connected with a shower head; the shower head is located directly above the simulated road surface layer;

[0011] The first drain pipe is provided with a first flow regulating valve and a first flow meter, and the water pumping pipe is provided with a second flow regulating valve and a second flow meter.

[0012] A driving risk assessment method for a waterlogged road surface on a rainy day, based on the above-mentioned simulated device for a waterlogged road surface on a rainy day, comprising the following steps:

[0013] Step 1: constructing a physical model of the water depth of each flow area according to the geometric characteristics of the water distribution, and obtaining a water depth calculation formula;

[0014] Step 2: adjusting the slope of the simulated road surface layer, the rainfall intensity and the drainage intensity in the simulated device for a waterlogged road surface on a rainy day for multiple times, simulating the actual waterlogging state of the slope section, reading the water depth at different positions, and obtaining multiple groups of measured data;

[0015] Step 3: converting the water depth calculation formula into a water depth fitting formula, fitting and optimizing the water depth fitting formula in combination with the measured data, and obtaining a water depth prediction model;

[0016] Step 4: determining the critical water depth of the waterlogged section;

[0017] Step 5: obtaining the estimated road water depth h through the water depth prediction model according to the actual road slope, rainfall intensity and drainage intensity;

[0018] Step 6: when the estimated road water depth h is less than 0.8h c , the driving risk is low; when the estimated road water depth h is less than h c and greater than or equal to 0.8h c , the driving risk is high; and when the estimated road water depth h is greater than or equal to h c , the driving risk is extremely high.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: The device of the present invention can better simulate the water accumulation state of the road surface in rainy weather. The method of the present invention adopts a combination of experiment and model regression to systematically carry out research on the water accumulation depth of road sections under the coupled effects of multiple factors such as slope, rainfall intensity, drainage intensity, and time. At the same time, it reduces the impact of the uncertainty of natural rainfall and proposes a water accumulation depth prediction model and driving risk index, which helps to correctly guide the design and maintenance of road drainage and also helps to provide reasonable road surface adhesion parameters for the future driving of unmanned vehicles in rainy weather. Attached Figure Description

[0020] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0021] Figure 1 This is a schematic diagram of the overall structure of an embodiment of the device of the present invention;

[0022] Figure 2 This is a schematic diagram of the exploded structure of the simulation box in an embodiment of the device of the present invention;

[0023] Figure 3 This is a schematic diagram of the structure of the nut washer plate in an embodiment of the device of the present invention;

[0024] Figure 4 This is a geometric model of the water depth per unit length of the road surface in the method of the present invention.

[0025] Explanation of reference numerals in the attached drawings: 1 Support plate, 2 Support rod, 201 Nut, 202 Foot plate, 203 Nut washer, 204 Ball bearing, 3 Simulation box, 301 Simulated road surface layer, 302 Sealing ring, 303 First drain outlet, 4 Sedimentation tank, 5 Pumping tank, 501 Pumping pump, 6 Pumping pipe, 7 Shower head, 8 First flow regulating valve, 9 First flow meter, 10 Second flow regulating valve, 11 Second flow meter, 12 Slope measuring component, 13 Level bubble, 14 Bearing plate, 15 Caster wheel. Detailed Implementation

[0026] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are only for illustrating the present invention and should not be regarded as limiting the scope of the present invention.

[0027] A device for simulating flooded roads during rain, reference Figure 1 , Figure 2 The system includes a support plate 1, which has multiple first through holes. A support rod 2 passes through each first through hole. The support rod 2 has threads and a nut 201 that matches the threads is fitted onto the support rod 2. The nut 201 is located below the support plate 1. A foot plate 202 is provided at the lower end of the support rod 2.

[0028] The support plate 1 is provided with a simulation box 3, the bottom plate of the simulation box 3 is provided with a simulation pavement layer 301, the upper surface area of the simulation pavement layer 301 is smaller than the area of the bottom plate of the simulation box 3, and a notched sealing ring 302 is arranged between the edge of the simulation pavement layer 301 and the side wall of the simulation box 3; the lower part of one side wall of the simulation box 3 is provided with a first drainage port 303, and the position of the notch of the sealing ring 302 corresponds to the first drainage port 303;

[0029] The device further comprises a sedimentation tank 4, the top plate of the sedimentation tank 4 is provided with a first water inlet, the first water inlet is connected with the first drainage port 303 through a first drainage pipe, and the upper part of one side wall of the sedimentation tank 4 is provided with a second drainage port;

[0030] The device further comprises a water pumping tank 5, the upper part of one side wall of the water pumping tank 5 is provided with a second water inlet, the second water inlet is connected with the second drainage port through a second drainage pipe, and the bottom plate of the water pumping tank 5 is provided with a water pumping pump 501, the water outlet of the water pumping pump 501 is connected with a water pumping pipe 6, and the other end of the water pumping pipe 6 is connected with a shower head 7; the shower head 7 is located directly above the simulation pavement layer 301;

[0031] The first drainage pipe is provided with a first flow regulating valve 8 and a first flow meter 9, and the water pumping pipe 6 is provided with a second flow regulating valve 10 and a second flow meter 11.

[0032] Further, the device further comprises a bubble level 13 and two slope measurement assemblies 12, the bubble level 13 is arranged on the upper surface of the support plate 1, and the bubble level 13 is used for preliminary leveling of the simulation pavement layer 301; the slope measurement assemblies 12 are arranged on the upper surface of the support plate 1, and the slope measurement assemblies 12 are used for measuring the slope of the simulation pavement layer 301; the measurement directions of the two slope measurement assemblies 12 are orthogonal.

[0033] Further, the side wall of the simulation box 3 is provided with a scale, the material of the side wall of the simulation box 3 is an acrylic plate, the acrylic plate has good light transmittance, so that the water accumulation height can be directly observed.

[0034] Further, the inner surface of the side wall of the simulation box 3 is provided with a hydrophobic SiO2 particle film, so that the splashed water droplets cannot adhere to the side wall, thereby avoiding the inaccuracy of the drainage amount collection and the instability of the flow meter reading caused by the water droplets adhering to the side wall; and the hydrophobic SiO2 particle film is colorless and transparent, and does not affect the light transmittance of the acrylic plate.

[0035] Further, reference is made to Figure 3Further comprising a nut backing plate 203, the lower surface of the nut backing plate 203 is provided with a groove, the groove is provided with a freely rotating ball 204, the nut backing plate 203 is sleeved on the supporting rod 2 and located between the supporting plate 1 and the nut 201; The upper surface of the nut 201 is provided with an annular sliding rail corresponding to the position of the ball 204. The nut backing plate 203 and the ball 204 are used to reduce component wear, increase effective wire connection area, prevent wire slipping, reduce the torsional resistance of the nut 201, and improve the durability of the device.

[0036] Further, it further comprises a bearing plate 14, the upper surface of the bearing plate 14 is fixedly connected with the lower surface of the foot plate 202, and the lower surface of the bearing plate 14 is provided with a universal wheel 15, so that the simulation device is convenient to move.

[0037] The height of the side wall of the simulation box 3 depends on the splashing height of the liquid drop. Research shows that the adhesion spreading, crown geometry movement and splashing movement generated after the liquid drop hits the wall surface depend on the kinetic energy of the liquid drop, and the capillary breakup phenomenon is proportional to the impact velocity and inversely proportional to the thickness of the liquid film. Therefore, the maximum pumping power of the water pump 501, the open state of the second flow regulating valve 10, and the unit liquid drop are taken for mechanical energy analysis, and the height of the side wall of the simulation box 3 is calculated as follows:

[0038]

[0039] Wherein, a is the height of the side wall of the simulation box 3; H is the average distance between the bottom surface of the shower 7 and the upper surface of the simulation road surface layer 301; m is the mass of the liquid drop; is the average initial velocity of the liquid drop; ΔE is the mechanical energy loss caused by the viscosity of the water film and the roughness of the upper surface of the simulation road surface layer 301; η is the reduction factor considering the shape of the liquid drop, the incident angle, the splashing angle, the temperature and the like.

[0040] A driving risk assessment method for a waterlogged road surface on a rainy day, based on the above-mentioned simulation device for a waterlogged road surface on a rainy day, comprising the following steps:

[0041] Step 1, according to the geometric characteristics of the water distribution, a physical model of the cross-sectional area water depth is constructed, and a water depth calculation formula is obtained;

[0042] Specifically, referring to Figure 4 , take a unit length Δs along the road direction, set the slope as θ, the road width as l, the water depth at the slope foot as m, the water depth at a distance x from the slope foot as h, and the water horizontal projection width as w, then according to the geometric characteristics of the water distribution, a cross-section physical model is constructed, and the following relationship is obtained:

[0043] h=(l-x)×sinθ

[0044] m=l×sinθ

[0045] w = l x cos θ

[0046] Then the total volume of water is:

[0047]

[0048] Again, V = V j -V p , where V j is the amount of precipitation, V p is the amount of drainage; then the water depth h at a distance x from the slope foot is:

[0049]

[0050] In the formula, V j is the amount of precipitation, V p is the amount of drainage, θ is the road slope, Δs is the unit length, and x is the distance from the slope foot.

[0051] Step 2, adjust the slope of the simulated road surface layer, the intensity of precipitation and the intensity of drainage in the simulated device of the waterlogged road surface on rainy days multiple times, simulate the real waterlogging state of the slope section, read the water depth at different positions, and obtain multiple sets of measured data;

[0052] When reading the water depth at different positions, a water level probe can be used in combination with the scale on the simulation box to read.

[0053] The intensity of precipitation is determined by the power of the water pump and the opening and closing degree of the second flow regulating valve. First, adjust the power of the water pump to roughly approximate the required value, and then fine-tune the second flow regulating valve for accurate control. The actual precipitation intensity is as follows:

[0054]

[0055] In the formula, I j is the intensity of precipitation, V j is the amount of precipitation, t j is the precipitation time, v j is the real-time flow rate recorded by the second flowmeter, A j is the cross-sectional area of the water pump, and A f is the precipitation coverage area.

[0056] The intensity of drainage is controlled by the first flow regulating valve and calculated by the following formula:

[0057]

[0058] In the formula, I p is the intensity of drainage, V p is the amount of drainage, t p is the drainage time, and v pReal-time flow rate recorded for the first flow meter; A p Cross-sectional area of the first drain pipe.

[0059] Step 3, convert the accumulated water depth calculation formula into an accumulated water depth fitting formula, combine the measured data to fit and optimize the accumulated water depth fitting formula, and obtain an accumulated water depth prediction model;

[0060] Specifically, the accumulated water depth fitting formula is as follows:

[0061]

[0062] In the formula, x1 is the slope, x2 is the precipitation, x3 is the drainage, x4 is the longitudinal length, and x5 is the distance from the slope foot.

[0063] Substitute the measured data into the First Optimization software, and fit and optimize the accumulated water depth fitting formula through program language; wherein the program language is as follows:

[0064] Title "Water depth model optimization";

[0065] Parameter p(1:8);

[0066] Variable x1, x2, x3, x4, x5, y;

[0067] F(y)=p5*sin(p6*π*x1+p7)*(((p1*(x2–x3)+p2) / (x4*sin(p3*π*x1+p4))^(0.5)–x5)+p8;

[0068] Data (not completely listed):

[0069]

[0070] The accumulated water depth prediction model is obtained, as shown in the following formula:

[0071]

[0072] In the formula, h is the accumulated water depth at a distance x from the slope foot, θ is the road surface slope, V j is the precipitation, V p is the drainage, and x is the distance from the slope foot.

[0073] Step 4, determine the critical accumulated water depth of the accumulated water section;

[0074] Let ρ be the liquid flow density, b be the tire width, r be the tire radius, α be the angle between the tire and the water film, v be the vehicle driving speed, and the flow beam be hindered by the tire and be stagnant at the tire grounding, then the momentum theorem is used along the normal direction of the contact surface to obtain the vertical lifting force F of the water flow on the tire:

[0075] dF y = -ρv 2 br cosαdα

[0076] The water flow vertical lifting force F of the water flow on the tire is obtained by integrating in the flow beam depth range y :

[0077]

[0078] When the road surface slope is θ, the vehicle is assumed to be in water sliding when Gcosθ=F is satisfied y , and the critical water depth h c is calculated as follows:

[0079]

[0080] In the formula, r is the tire radius, G is the vehicle single-wheel load, θ is the road surface slope, ρ is the liquid flow density, v is the vehicle driving speed, and b is the tire width.

[0081] The critical water depth of the road section is determined according to the general parameters of the vehicle passing through the waterlogged road section.

[0082] Step 5, the estimated water depth h of the road section is obtained according to the actual road surface slope, the rainfall intensity and the drainage intensity through the water depth estimation model;

[0083] Step 6, when the estimated water depth h of the road section is less than 0.8h c , the driving risk is low, and the daily maintenance of the drainage facilities should be strengthened; when the estimated water depth h of the road section is less than h c and greater than or equal to 0.8h c , the driving risk is high, and the drainage capacity of the existing drainage facilities of the road should be improved; when the estimated water depth h of the road section is greater than or equal to h c , the driving risk is extremely high, and the drainage facilities of the road should be increased to strengthen the drainage capacity.

[0084] Simulation test

[0085] Under the conditions of the same drainage capacity, different rainfall intensities and different road surface slopes, the estimated water depth of the road section obtained by the water depth estimation model of the application is compared with the measured average water depth of the road section, and the comparison results are shown in Table 1.

[0086]

[0087] As can be seen from Table 1, it can be seen that the water accumulation depth prediction model of the application can predict the water accumulation depth of the road surface under different rainfall intensities.

[0088] Although the present application has been described in detail with general description and specific embodiments in the specification, some modifications or improvements can be made on the basis of the present application, which is obvious to those skilled in the art. Therefore, these modifications or improvements made on the basis of not deviating from the spirit of the present application, all belong to the scope of protection claimed by the present application.

Claims

1. A method for evaluating driving risk on a road surface with accumulated water on a rainy day, characterized by, The method comprises the following steps: Step 1: Construct a physical model of water depth of each flow area according to the geometric characteristics of water distribution, and obtain a water depth calculation formula, which is specifically shown in the following formula: where V j is the precipitation, V p is the drainage, θ is the road surface slope, Δs is the unit length, and x is the distance from the slope foot; Step 2: Adjust the slope of the simulated pavement layer, the rainfall intensity and the drainage intensity in the simulated device of the rainwater accumulation pavement multiple times to simulate the actual water accumulation state of the slope section, read the water depth at different positions, and obtain multiple groups of measured data; The simulated device comprises a support plate (1), a plurality of first through holes are arranged on the support plate (1), a support rod (2) penetrating through each first through hole is arranged in each first through hole, threads are arranged on the support rod (2), nuts (201) matched with the threads are arranged on the support rod (2), and the nuts (201) are located below the support plate (1); a foot plate (202) is arranged at the lower end of the support rod (2); a simulation box (3) is arranged on the support plate (1), a simulated pavement layer (301) is arranged on the bottom plate of the simulation box (3), the area of the upper surface of the simulated pavement layer (301) is smaller than the area of the bottom plate of the simulation box (3), and a sealing ring (302) with a notch is arranged between the edge of the simulated pavement layer (301) and the side wall of the simulation box (3); a first drainage port (303) is arranged at the lower part of one side wall of the simulation box (3), and the position of the notch of the sealing ring (302) corresponds to the first drainage port (303); Further comprising a sedimentation tank (4), a first water inlet is arranged on the top plate of the sedimentation tank (4), the first water inlet is connected with the first drainage port (303) through a first drainage pipe, and a second water inlet is arranged at the upper part of one side wall of the sedimentation tank (4); Further comprising a water pumping tank (5), a second water inlet is arranged at the upper part of one side wall of the water pumping tank (5), the second water inlet is connected with the second drainage port through a second drainage pipe, and a water pumping pump (501) is arranged on the bottom plate of the water pumping tank (5); a water pumping pipe (6) is connected to the water outlet of the water pumping pump (501), and a shower head (7) is connected to the other end of the water pumping pipe (6); the shower head (7) is located directly above the simulated pavement layer (301); A first flow adjusting valve (8) and a first flow rate meter (9) are arranged on the first drainage pipe, and a second flow adjusting valve (10) and a second flow rate meter (11) are arranged on the water pumping pipe (6); Step 3: convert the water depth calculation formula into a water depth fitting formula, combine the measured data to fit and optimize the water depth fitting formula, and obtain a water depth prediction model; Specifically, the water depth fitting formula is shown in the following formula: In the formula, x1 is the road surface slope (θ), x2 is the precipitation (V j ), x3 is the drainage (V p ), x4 is the unit length (Δs), x5 is the distance from the slope foot (x), and p1-p8 are empirical correction coefficients of the ponding depth fitting formula. Step 4, determining the critical water depth h of the waterlogged section c ; Step 5: obtain the predicted water depth h of the road surface according to the actual road surface slope, rainfall intensity and drainage intensity through the water depth prediction model; Step 6, when the estimated road water depth h is less than 0.8h c , the driving risk is low; when the estimated road water depth h is less than h c and greater than or equal to 0.8h c , the driving risk is high; when the estimated road water depth h is greater than or equal to h c , the driving risk is extremely high.

2. The method of claim 1, wherein the method further comprises: The simulated device of step 2 further comprises a bubble level (13) and two slope measurement assemblies (12), the bubble level (13) is arranged on the upper surface of the support plate (1), and the slope measurement assemblies (12) are arranged on the upper surface of the support plate (1); the slope measurement assemblies (12) are used for measuring the slope of the simulated pavement layer (301), and the measurement directions of the two slope measurement assemblies (12) are orthogonal.

3. The method of claim 1, wherein the method further comprises: The side wall of the simulation box (3) of step 2 is provided with a scale, and the material of the side wall of the simulation box (3) is an acrylic plate.

4. The method of claim 1, wherein the method further comprises: The inner surface of the side wall of the simulation box (3) of step 2 is provided with a hydrophobic SiO2 particle film.

5. The method of claim 1, wherein the method further comprises: The simulation device of step 2 further comprises a nut backing plate (203), the lower surface of the nut backing plate (203) is provided with a groove, the groove is provided with a freely rotatable ball (204), the nut backing plate (203) is sleeved on the supporting rod (2) and located between the supporting plate (1) and the nut (201); the upper surface of the nut (201) is provided with an annular sliding rail corresponding to the position of the ball (204).

6. The method for assessing the driving risk of a water-accumulating road surface on a rainy day according to Claim 1, wherein The accumulated water depth estimation model in step 3 is specifically as follows: where h is the depth of the water at a distance x from the toe of the slope, θ is the road surface gradient, V j is the precipitation, V p is the discharge, and x is the distance from the toe of the slope.

7. The method for assessing the driving risk of a water-accumulating road surface on a rainy day according to Claim 1, wherein The critical accumulated water depth in step 4 is specifically calculated as follows: In the formula, r is the tire radius, G is the single wheel load of the vehicle, θ is the road slope, ρ is the liquid flow density, v is the vehicle speed, and b is the tire width.

Images