CN111879645A - Roadbed slope hydrodynamic stability characteristic analysis experimental device - Google Patents
Roadbed slope hydrodynamic stability characteristic analysis experimental device Download PDFInfo
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Abstract
The invention provides a roadbed slope hydrodynamic stability characteristic analysis experimental device which comprises a water inlet pipe, a water collecting tank, a liquid pressurizer, two flowmeters and a hydrodynamic simulation water outlet structure, wherein the water inlet pipe is connected with the water collecting tank; the water inlet pipe, the water collecting tank and the hydrodynamic force simulation water outlet structure are sequentially connected, a liquid pressurizer and two flowmeters are arranged on a water pipe between the water collecting tank and the hydrodynamic force simulation water outlet structure, and the two flowmeters are connected in parallel and have one large measuring range and one small measuring range. The problem that no proper experimental device is used for measuring and analyzing the hydrodynamic stability characteristics of the roadbed slope and the problem that the change of the size of a test piece and the slope of the slope is limited in slope experimental research and analysis is solved, the experimental device for analyzing the hydrodynamic stability characteristics of the roadbed slope is provided, the experimental conditions for simulating the water action can be flexibly changed, and a plurality of slope hydrodynamic characteristic parameters can be effectively simulated and analyzed.
Description
Technical Field
The invention particularly relates to a roadbed slope hydrodynamic stability characteristic analysis experimental device which can be used for analyzing the stability of a roadbed structure slope and hydrodynamic stability characteristics of the roadbed structure slope, and belongs to the technical field of analysis experimental devices.
Background
The water flow state is the basic hydrodynamic characteristic of the slope surface flow, and is one of the hot problems in the field of studying the slope surface laminar flow. The flow state of the thin layer slope surface water flow is extremely complex, the problem of the flow state of the thin layer slope surface water flow is still studied at present, and meanwhile, the flow velocity of the slope surface water flow is an important parameter for determining the form of the slope surface water flow and further researching the erosion mechanism of the slope surface water flow. At present, most of domestic and foreign researches on the rainwater erosion of the side slope stay in a theoretical stage, and few researches are conducted on the rainwater erosion effect of the side slope through an experimental mode. In the prior art, the flow state of the slope laminar flow is mostly judged from the traditional hydraulic point of view, but for the slope laminar flow caused by rainfall, especially under the condition of existing geocells, the boundary conditions are relatively complex, and currently, there are few research results, and the fundamental reason is the difficulty of experiments and monitoring work.
Therefore, a set of experimental device capable of simulating rainfall environment of an actual side slope is developed, which is particularly important for researching the rain erosion resistance of the side slope, the hydrodynamic scouring device is designed and manufactured by self and is applied to the experimental research of the erosion resistance stability of the roadbed side slope, and the design and the use of the device are continuously innovated and improved through a test, so that the experimental device adopts a research method combining multiple disciplines and is also a courage attempt.
Disclosure of Invention
In order to solve the problems mentioned in the background art and solve the problems that no proper experimental device is used for measuring and analyzing the hydrodynamic stability characteristics of the roadbed slope and the size and slope change of a test piece in the slope experimental research and analysis are limited, the invention provides the experimental device for analyzing the hydrodynamic stability characteristics of the roadbed slope, the experimental conditions for simulating the water action can be flexibly changed, and a plurality of slope hydrodynamic characteristic parameters can be effectively simulated and analyzed.
The invention provides a roadbed slope hydrodynamic stability characteristic analysis experimental device which comprises a water inlet pipe, a water collecting tank, a liquid pressurizer, two flowmeters and a hydrodynamic simulation water outlet structure, wherein the water inlet pipe is connected with the water collecting tank; the water outlet structure is simulated by the water inlet pipe, the water collecting tank and the hydrodynamic force and is connected in sequence, a liquid pressurizer and two flow meters are arranged on a water pipe between the water collecting tank and the hydrodynamic force simulation water outlet structure, and the two flow meters are connected in parallel and are one large measuring range and one small measuring range.
Preferably, the hydrodynamic force simulation water outlet structure is a rain box, which is used for simulating a high-altitude rainfall process, a plurality of shunt branches are installed on the upper portion of the rain box, a plurality of rainfall needles are installed under the rain box, and the top of the rain box is divided into a plurality of branches after water enters the top of the rain box and uniformly flows into a needle arrangement area of the rain box.
More preferably, the rain box is cuboid and has the dimensions of 250cm long, 150cm wide and 40cm high.
More preferably, the roadbed slope hydrodynamic stability characteristic analysis experimental device further comprises a limiting water pipe, the limiting water pipe is divided into two sections, the two sections are connected end to end and are perpendicular to each other, the front section of the limiting water pipe is connected with the water collection tank, the rear section of the limiting water pipe is perpendicularly downwards connected with the floor drain, and the height of the water level in the water collection tank is limited through the limiting water pipe.
More preferably, the diameter of the water collecting tank is 110cm, the height of the water collecting tank is 150cm, and the upper part of the water collecting tank is provided with a limiting water pipe which can keep the water level at 110cm height.
More preferably, the rain needle head is an industrial glue clamping needle head, and can be switched according to test requirements, so that the purpose of adjusting the particle size of the raindrops is achieved.
Preferably, the hydrodynamic force simulation water outlet structure is a water flow box, the water flow box is placed on the ground and used for simulating a surface water flow process, a water outlet of the water flow box is communicated with a plurality of water outlet pipes, and each water outlet pipe is provided with a valve.
More preferably, the number of the water outlet pipes is 11, the diameter of the water outlet pipes is 4cm, and the distance between the water outlet pipes is 5 cm.
Preferably, the liquid pressurizer adopts an ORS25-10 type hydraulic pressure booster, the rated voltage is 220V-50Hz, the input/output power is 200W, the maximum flow is 3 tons/hour, and the pipe diameter is 4 minutes.
Preferably, the two flowmeters adopt glass rotor flowmeters, wherein the measuring range of one flowmeter is 25-250mL/min, and the measuring range of the other flowmeter is 250-2000 mL/min.
The roadbed slope hydrodynamic stability characteristic analysis experimental device has the beneficial effects that:
the device comprises a rainfall simulation device and a water flow scouring device, wherein the rainfall simulation device has the characteristics of large volume, simplicity and easiness in operation and high accuracy, and the design idea of the device is utilized to have important significance for researching the hydrodynamic scouring device. The water flow scouring device is mainly used for simulating the scouring action of overflowing flow or runoff on the slope surface on the basis of rainfall conditions, so that the influence of the scouring action of the water flow on the slope surface is explored.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention.
In the drawings:
fig. 1 is a schematic structural diagram of a rainfall simulation device according to a first embodiment of the experimental apparatus for analyzing hydrodynamic stability characteristics of a slope of a roadbed;
FIG. 2 is a bottom view of the rain box of the present invention;
FIG. 3 is a perspective view of a rain box according to the present invention;
fig. 4 is a schematic structural diagram of a surface water flow simulation device according to a second embodiment of the experimental apparatus for analyzing hydrodynamic stability characteristics of a roadbed slope;
FIG. 5 is a perspective view of the water flow box of the present invention;
in the figure: 1-water inlet pipe; 2-a water collecting tank; 3-limiting water pipes; 4-a liquid pressurizer; 5-a valve; 6-a flow meter; 7-a shunt branch; 8-rain box; 9-a rainfall needle; 10-water outlet pipe; 11-water flow box.
Detailed Description
The following detailed description of embodiments of the invention is provided in conjunction with the appended drawings:
1. basis of design
The device is designed on the basis of the development process of the side slope soil body scouring under the condition. From the point of view of hydrodynamic force source causing the scouring of the broken surface, rainfall is the most main power factor, raindrops impact soil particles on the surface layer of the broken surface at a certain speed under the action of gravity, so that the soil particles are separated from soil body, become loose particles, and make part of the soil particles jump, and the splashing action forms the initial form of the scouring of the slope surface and simultaneously provides abundant loose particles for subsequent runoff carrying. When the rainfall is larger than the infiltration amount of the slope soil, the raindrops are converged into thin layer surface flow on the slope, or further slope runoff with a certain depth is formed. The slope water flow is the main power source for scouring, and plays roles in scouring and carrying the slope soil body to cause the slope scouring. Summarizing, the factors causing the slope scouring mainly include raindrop splash erosion, surface overflow and surface runoff in the rainfall process, wherein the surface runoff is an important factor of the slope scouring. The test apparatus needs to simulate the most realistic scouring action of a rainfall slope.
The rainfall characteristics comprise rainfall, rainfall intensity, rainfall duration, raindrop characteristics and the like, and the change of the characteristics can cause the damage degree of the slope surface water scouring to change, so that the influence of the factors needs to be considered by the test device.
2. Detailed device
The hydrodynamic scouring device provided by the invention has two embodiments, different simulation processes are set respectively aiming at different tests, and hydrodynamic conditions of broken surface scouring in the whole rainfall process are simulated. The first embodiment is a rainfall simulation device, which embodies the scouring effect of raindrop splash on a slope surface; the second embodiment is a device for simulating surface water flow, which embodies the scouring effect of surface overflow or runoff on the slope.
The first embodiment is as follows: the present embodiment is explained with reference to fig. 1 to 3. The roadbed slope hydrodynamic stability characteristic analysis experimental device comprises a water inlet pipe 1, a water collecting tank 2, a liquid pressurizer 4, two flowmeters 6 and a hydrodynamic simulation water outlet structure; the water outlet structure is simulated by the water inlet pipe 1, the water collecting tank 2 and the hydrodynamic force and is connected in sequence, the water collecting tank 2 and the hydrodynamic force are used for simulating a water pipe between the water outlet structure and are provided with a liquid pressurizer 4 and two flowmeters 6, and the two flowmeters 6 are connected in parallel and are one large range and one small range.
Hydrodynamic force simulates out water structure and is rain box 8, and it is used for simulating the rainfall process of eminence, rain box 8 upper portion is installed a plurality of reposition of redundant personnel branch roads 7, install a plurality of rainfall syringe needles 9 under the rain box 8, the reposition of redundant personnel is the syringe needle 9 arrangement area that a plurality of branch roads evenly flowed in rain box 8 after 8 tops of rain box were intake.
The roadbed slope hydrodynamic stability characteristic analysis experimental device further comprises a limiting water pipe 3, the limiting water pipe 3 is divided into two sections, the two sections are connected end to end and are perpendicular to each other, the front section of the limiting water pipe 3 is connected with the water collecting tank 2, the rear section of the limiting water pipe is perpendicularly connected with a floor drain downwards, and the height of the water level in the water collecting tank 2 is limited through the limiting water pipe 3.
The diameter of the water collecting tank 2 is 110cm, the height of the water collecting tank is 150cm, and the upper part of the water collecting tank 2 is provided with a limiting water pipe 3 which can keep the water level at 110 cm.
The rainfall needle head 9 adopts an industrial glue clamping needle head and can be switched according to test requirements, so that the aim of adjusting the particle size of raindrops is fulfilled.
The rainfall simulation device mainly comprises a water supply system, a power system, a control system and a rainfall system,
the water supply system mainly comprises a water collecting tank 2, a water inlet pipe 1, a limiting water pipe 3 and the like, and has the main function of collecting water flow of the water inlet pipe, and the limiting water pipe 3 limits the fixed height of the water level in the water collecting tank 2, so that the water flow flowing through the water outlet pipe is conveyed to the rainfall system of the device under constant water pressure. The water inlet pipe 1 is connected with a faucet, a water outlet of the limiting water pipe 3 is connected with a floor drain, a precipitation system is a key for keeping the stability of rainfall intensity, the diameter of the water collecting tank 2 is 110cm, the height of the water collecting tank is 150cm, the limiting water pipe 3 is arranged on the water collecting tank, and the water level can be kept to be controlled at the height of 110 cm.
The power system is composed of a liquid pressurizer 4, an ORS25-10 type hydraulic pressure pressurizer is adopted, the rated voltage is 220V-50Hz, the input/output power is 200W, the maximum flow is 3 tons/hour, the pipe diameter is 4 minutes (15/20mm), and the characteristics of continuous and stable pressurization are achieved.
The control system is mainly controlled in a manual mode, comprises two flowmeters 6 and the like, and is used for controlling water pressure and adjusting rainfall intensity. The range of natural rainfall in a weather forecast issued by a meteorological department is 0-250 mm/h, and the range is selected according to the rainfall range simulated by the device as follows: the flowmeters with the specifications of 25-250mL/min and 0.25-2L/min are alternately matched for use, the control range of the flowmeter 6 is enlarged, the flowmeter 6 with the small measuring range is opened when the water flow is small, and the flowmeter 6 with the large measuring range is opened when the water flow is large. The two flowmeters 6 adopt glass rotor flowmeters, wherein the measuring range of one flowmeter 6 is 25-250mL/min, and the measuring range of the other flowmeter 6 is 250-2000 mL/min.
The rainfall system mainly comprises a rain box 8 which is a generation part of raindrops and is used for uniformly distributing the water flow of the water inlet pipe 1 and supplying the water flow to each rainfall needle 9 to generate the raindrops. The rain box 8 is made of organic glass and is a carrier of a rainfall needle 9, the rain box 8 is cuboid, the length of the rain box is 250cm, the width of the rain box is 150cm, the height of the rain box is 40cm, 8 shunt branches 7 are installed at the upper part of the rain box, and after water enters the water inlet pipe, the water is shunted into 8 branches which uniformly flow into a needle 9 arrangement area of the rain box 8. The lower surface distribution of rain box 8 has 336 syringe needle sockets, and the interval is 10mm, and 9 sockets of syringe needle are the cutting installation of 2.5ml medical syringe cylinder and form, and the syringe needle adopts industry card to glue the syringe needle, can freely switch according to experimental requirement to reach the purpose of adjusting the raindrop particle diameter.
The working principle is as follows: the water inlet pipe 1 is connected to a tap, water is conveyed to the water collecting tank 2 by using tap water pressure, the water level in the water collecting tank 2 rises until water flows out of the limiting pipe 3, and the water level in the water collecting tank 2 is kept constant at 110cm at the moment. The fixed water head height in the water collecting tank 2 generates fixed water pressure, so that the water flow flowing through the water outlet pipe 10 and the flow meter 6 is constant, the water flow is divided into a plurality of branches after passing through the branch flow 7, and uniformly flows into the rain box 8, and raindrops are formed by the industrial glue clamping needle head 9 and fall on a side slope sample to complete the whole rainfall simulation process.
Analysis of specific test parameters:
the rainfall produced by the ideal indoor rainfall simulation device is the same as the natural rainfall in the nature, the characteristics of the natural rainfall in the nature are many and similar, the characteristics of the natural rainfall are difficult to accurately realize under the current conditions, and the design aim of the device is to realize the rainfall characteristics related to the research content of the subject. For this purpose, it is necessary to grasp the main rainfall characteristics relevant to the subject study, for example, the parameters usually used as rainfall erosive power include: rain drop particle size and rainfall rate. Therefore, the rainfall characteristics considered in the performance test of the device comprise: (1) intensity of rainfall; (2) the raindrop particle size; (3) the degree of uniformity of rainfall; (4) the landing end speed of raindrops, and the like.
(1) Intensity of rainfall
The rainfall intensity is the amount of rainfall in a unit time period, and can be represented by the rainfall depth (mm/min or mm/h) in a unit time, or the rainfall volume (L/(s · m2)) in a unit area in a unit time, and is an important index for describing rainfall, and the rainfall intensity is larger, and the rainfall is more violent. At present, the rainfall intensity standard generally adopted by the meteorological department in China is shown in table 1.
TABLE 1 rainfall intensity rating Scale
The purpose of the test is to test the rainfall intensity of the indoor rainfall simulation device, search the operation rule of the device and the optimal operation method, and summarize and calibrate the rainfall intensity value of the device. Rainfall intensity is an important characteristic of natural rainfall, so how to accurately simulate and control the rainfall intensity is an important problem to be considered by an indoor rainfall simulation test device. At present, the method for controlling rainfall intensity by using a domestic rainfall simulation device mainly comprises the steps of regulating flow and controlling pressure. In the test, factors such as the device and the test conditions on the spot are considered, and a method for controlling the rainfall intensity by adjusting the flow is adopted. The method has the advantages of strong stability, convenient control and the like. According to the assumption that the water flow of the water inlet pipe is mutually associated with the rainfall measured on the sample table, the rainfall values under different flows are recorded in the test, so that a function relation between the flow and the rainfall is obtained, and the purpose of controlling the rainfall can be achieved only by indirectly controlling the flow in the rainfall test process.
Theoretically, the amount of water flowing into the rain box and the amount of water flowing out are in a direct proportion relationship, and the rain box of the rainfall device is known, so a theoretical formula can be obtained:
wherein: q is rainfall intensity, mm/h; a is rainfall area, mm2(ii) a F is water flow, mm3H; the rain box length a is 2500mm, the width b is 1500mm, and f is the flow meter reading mL/min.
In order to accurately control the water flow and accurately measure the water flow, a glass rotameter is adopted for flow control and observation in the test, and the flow is controlled by adjusting a control knob on the glass rotameter, so that the flowmeter is convenient to mount and debug and relatively reliable in precision, a water collecting tank 2 and a limiting water pipe 3 in the device can control the water level, the stability of the water flow is kept, and meanwhile, the stability of the working state of the glass rotameter is kept.
Because glass rotameter's pipe diameter is very little, and water pressure consumes greatly, and the flow that header tank 2 goes out water does not reach the predetermined value, consequently installs liquid presser 4 between header tank 2 and flowmeter 6, and the booster model is: ORS25-10, rated voltage: 220V-50Hz, input/output power: 200W, maximum lift: 10m, maximum flow: 3t/h, and the connecting pipe diameter is 4 minutes (15/20 mm).
(2) The raindrop particle size:
raindrops are a natural rainfall phenomenon, and raindrop splashing can damage the soil structure, so that the pores on the surface layer of the soil are reduced or blocked. Therefore, observing raindrops is an important work for researching natural rainfall and rainfall simulation characteristics and designing a rainfall simulation device.
Raindrop particle size is an important characteristic of natural rainfall. Under normal conditions, raindrops of natural rainfall fall from the bottom of a cloud, and are subjected to the action of air resistance, most of the raindrops with the diameters exceeding the diameters are broken and dispersed, the particle size of the raindrops in rainstorm is generally 3-4 mm, the maximum particle size can reach 6mm, and the particle size of the raindrops in downy rain is below 0.5 mm. The method can accurately measure the particle size value of the raindrop by adopting a color spot method, and the corresponding raindrop particle size value is deduced by measuring the size of the color spot diameter formed by the raindrop on the same medium material on the basis of the assumption that the diameter of the color spot formed by the raindrop on the same material is in direct proportion to the particle size of the raindrop, so that the method has the advantages of simplicity in operation, high precision and the like. According to the research of related scholars, the diameters of filter paper color spots are sequentially increased along with the needle head models of 24G, 23G, 22G and 21G, so that the particle size value of raindrops can be judged according to the average value and the concentration degree of rainfall and color spot values under different conditions, and the corresponding needle hole models and the corresponding needle hole quantities can be designed according to the following relational equation of the filter paper color spots and the raindrop particle sizes so as to simulate the raindrop particle sizes under different levels of rain. Table 2 is a recommendation table for pinhole models:
TABLE 2 pinhole model recommendation table
(3) Degree of uniformity of rainfall
The uniformity of rainfall is an important characteristic of natural rainfall, is an important index for testing the performance of the rainfall simulation device, and is also a key condition related to whether the test result is accurate. This experimental apparatus is at first invariable through header tank 2 and spacing water pipe 3 control water pressure for the water speed and the water pressure that reach liquid presser 4 are more even, and liquid presser 4 keeps invariable power again, makes the water of input in the rain box 8 keep the stability of water pressure and speed. The design of 8 boxes of rain makes the water yield that finally flows each pinhole similar, and is comparatively even, the even degree of simulation actual rainfall that can be fine.
(4) Landing terminal velocity of raindrops
The raindrops vertically fall to the ground from high altitude, and if the process is free-fall movement, when the raindrops reach the ground, the terminal speed can reach hundreds of meters per second, and the damage to ground objects is great. However, in fact, the raindrops are mainly under the action of self gravity and the action of air buoyancy and resistance in the falling process, and the raindrops move at a uniform speed instead of continuously accelerating after falling for a certain distance under the action of the three components, wherein the speed at the time is called as the terminal speed of the raindrops falling to the ground. The device mainly researches the influence of rainfall on the soil, the splash erosion of the falling speed and the kinetic energy of raindrops on the soil and the damage of the structure are indexes which need to be considered, and the final speed of rainfall is required to be the same as the natural rainfall if the rainfall simulation device ideally realizes the natural rainfall, so that the damage effect of the raindrops on the soil is consistent with the natural rainfall.
A great deal of test research is carried out on the particle size of the natural rainfall raindrops by American meteorologist Ross et al, the distribution range of the sizes of the natural rainfall raindrops is 0-6 mm, the corresponding falling height required by more than 90% of the raindrops is 7-9 mm, and the falling speed can be guaranteed to reach the standard speed only if the raindrops fall from the height of 9m at least. However, in the case of the rainfall simulation device in this test, the raindrops have a certain initial velocity, so that the falling height thereof is relatively low. It is equivalent to the raindrops falling from a certain height, reaching the needle height, the velocity of the raindrops reaches V0, and then continuing to fall until reaching the end velocity. Therefore, the formula is obtained:
h3＝h1+h2
wherein: h3 is the effective rainfall height of the raindrops falling, h1 is the theoretical height of the raindrops falling from a static state to an initial speed in the air, h2 is the distance between the needle head and the plane of the test bed, namely the actual falling height of the raindrops,
wukui ao (1995) carries out correction calculation on the Sanyuqing formula and the Newton formula for calculating the raindrop speed to obtain a formula suitable for artificial rainfall simulation
The water supply pressure is known to be 0.01-0.1 Mpa, the initial speed of the raindrops flowing out of the needle head can be estimated approximately to be about 15m/s according to the fluid mechanics knowledge and the size of the needle hole, the theoretical height of the initial speed is calculated according to the formula and is h 1-7.5 m, and the corresponding falling height required for achieving the stable final speed is known to be 7-9 m, namely h 3-7-9 m; the distance of the needle from the test plane is found to be >1.5m according to the formula. Therefore, the working height of the indoor rainfall simulation device manufactured by the invention needs to be larger than the numerical value, and the requirement that the raindrops reach the final speed can be basically met.
TABLE 3 rainfall simulation device Performance indices
Test index selection is shown in table 4:
table 4 rainfall rating and test index selection
The selecting range is 25-250 mL/min; the water supply pressure is adjusted according to the reading of the flow meters with two specifications of 0.25L/min-2L/min.
The second embodiment is as follows: this embodiment is explained with reference to fig. 4 to 5. The roadbed slope hydrodynamics stability characteristic analysis experimental device is a surface water flow scouring device. The device for simulating surface water flow scouring also comprises a water supply system, a power system, a control system and a system for simulating surface water flow scouring.
The water supply system mainly comprises a water collecting tank 2, a water inlet pipe 1 and the like, wherein the diameter of the water collecting tank 2 is 40cm, and the height of the water collecting tank is 50 cm.
The power system is composed of a liquid pressurizer 4, the ORS25-10 type hydraulic pressure pressurizer is also adopted, the rated voltage is 220V-50Hz, the input/output power is 200W, the maximum flow is 3 tons/hour, the pipe diameter is 4 minutes (15/20mm), and the characteristics of continuous and stable pressurization are realized.
The control system is mainly controlled in a manual mode, comprises two flowmeters 6 and the like, and is used for controlling water pressure and adjusting rainfall intensity.
The system for simulating surface water flow scouring mainly comprises a water flow box 11, the water flow box is placed on the ground and used for simulating the surface water flow process, the water outlets of the water flow box 11 are communicated with 11 water outlet pipes 10 with the diameters of 4cm and the intervals of 5cm, each pipe opening is matched with one valve 5, when the overflowing is simulated, all the water outlet pipes 10 are in an open state, when the runoff is simulated, the valves 5 of the water outlet pipes 10 on the two sides are closed to stop the flowing water, and the middle water outlet pipe 10 works. Before the device works, a rainfall simulation test needs to be carried out firstly, so that the test side slope is fully wetted.
The working principle of the device for simulating surface water flow scouring is as follows: the designed surface water flow scouring device simulates the scouring effect of only the overflowing flow on the slope surface on the road surface, or the scouring effect of the runoff on the slope surface is formed on the road surface. The water collecting tank 2 can keep the water pressure flowing through the liquid pressurizer 4 stable, if the liquid pressurizer 4 also keeps constant pressure, the water outlet pipe 10 can finally flow out uniform water flow to simulate the uniformity of the water flow velocity of storm runoff in nature, and the flow meter is used for observing the water flow rate, so that the water flow intensity is adjusted through the flow meter, and the flow grade of rain is simulated.
Analysis of specific test parameters:
the rainfall levels to be simulated in the test are heavy rain, heavy rain and extra heavy rain, and the scouring caused by overflow and runoff generated by the test needs to be analyzed respectively.
(1) And (3) analyzing the diffuse flow: assuming that the influence of certain level of rain wash needs to be studied, the height of 24h of rain on the corresponding road surface is d, and the area of the test covering the road surface is 1.5 × 3.75 ÷ 2 ═ 2.813m2Then the flow of rainwater per minute is: q ═ sxd ÷ 24 ÷ 60, so that a flooding washout condition can be simulated as long as the meter reading is guaranteed to be within the desired rain flow range, which is selected from table 5 below.
Table 5 rainfall rating division flow range relation
2. Runoff analysis: the runoff needs to consider the scouring action of rain and water flow velocity on the slope, according to the runoff coefficient regulation of the design code of water supply and drainage of buildings, the runoff coefficient alpha is the ratio of the runoff depth R in any time period to the precipitation depth P in the same time period, the runoff coefficient of the asphalt pavement is 0.9, and the runoff depth corresponding to each rainfall grade can be obtained, as shown in table 6:
table 6 rainfall rating scale division and runoff depth
According to the runoff depth R ═ W ÷ F ÷ 1000,
wherein R is the depth of the radial flow in mm, W is the total amount of the radial flow in m3F is the area of the drainage basin in km2. In the device, F is the most unfavorable condition, namely the area of the covered road surface range (2.813 m)2) Thus, the total runoff W can be obtained.
W(mm/min)＝R×F×1000＝R×2.813×10-6×1000×109÷60＝R×46883.3mm/min
The calculated W value ranges are as follows in table 7:
TABLE 7 rainfall grading and runoff Total
The selecting range is 25-250 mL/min; the readings of the flowmeter with two specifications of 0.25L/min-2L/min correspond to the total runoff W.
Because of the difference of the friction coefficient of different road surfaces or road surface structure, the difference of the cross-sectional area of runoff is very big, causes the difference of runoff flow speed, and this experiment only uses a outlet pipe simulation runoff, only forms a diameter for 4cm quota runoff in the road surface scope of representing the experiment, has simulated the most unfavorable condition, the road surface runoff that the velocity of flow is the fastest, consequently, as long as guarantee the reading of flowmeter within the required runoff total amount W scope, can simulate the condition of washing away of runoff.
The above-mentioned embodiments further explain the objects, technical solutions and advantages of the present invention in detail. It should be understood that the above-mentioned embodiments are only examples of the present invention, and are not intended to limit the present invention, and that reasonable combinations of the features described in the above-mentioned embodiments can be also possible, and any modifications, equivalent substitutions, improvements and the like, which are within the spirit and principle of the present invention, should be included in the scope of the present invention.
Claims (10)
1. The experimental device for analyzing the hydrodynamic stability characteristics of the roadbed slope is characterized by comprising a water inlet pipe (1), a water collecting tank (2), a liquid pressurizer (4), two flowmeters (6) and a hydrodynamic simulation water outlet structure; the water outlet structure is simulated by the water inlet pipe (1), the water collecting tank (2) and the hydrodynamic force are provided with the liquid pressurizer (4) and the two flowmeters (6) on the water pipe between the water outlet structure, and the two flowmeters (6) are connected in parallel and have a large range and a small range.
2. The experimental apparatus for analyzing hydrodynamic stability characteristics of roadbed slope according to claim 1, wherein the hydrodynamic force simulation water outlet structure is a rain box (8) for simulating a high rainfall process, a plurality of branch circuits (7) are installed on the upper portion of the rain box (8), a plurality of rainfall needles (9) are installed under the rain box (8), and the top of the rain box (8) is divided into a plurality of branch circuits after water enters the rain box (8) and the branch circuits uniformly flow into a rainfall needle (9) arrangement area of the rain box (8).
3. The experimental apparatus for analyzing the hydrodynamic stability characteristics of the subgrade slope according to the claim 2, characterized in that the rain box (8) is rectangular, and has the dimensions of 250cm long, 150cm wide and 40cm high.
4. The roadbed slope hydrodynamic stability characteristic analysis experiment device according to claim 2, characterized in that the roadbed slope hydrodynamic stability characteristic analysis experiment device further comprises a limiting water pipe (3), the limiting water pipe (3) is divided into two sections, the two sections are connected end to end and perpendicular to each other, the front section of the limiting water pipe (3) is connected with the water collection tank (2), the rear section of the limiting water pipe is connected with a floor drain vertically downwards, and the height of the water level in the water collection tank (2) is limited through the limiting water pipe (3).
5. The experimental device for analyzing the hydrodynamic stability characteristics of the subgrade slope according to the claim 4, characterized in that the diameter of the water collection tank (2) is 110cm, the height of the water collection tank is 150cm, and the limiting water pipe (3) is installed at the upper part of the water collection tank (2) and can keep the water level at the height of 110 cm.
6. The experimental device for analyzing the hydrodynamic stability characteristics of the roadbed slope according to claim 2, wherein the rainfall needle (9) is an industrial glue-blocking needle which can be switched according to test requirements, so that the purpose of adjusting the particle size of raindrops is achieved.
7. The experimental apparatus for analyzing hydrodynamic stability characteristics of a roadbed slope according to claim 1, wherein the hydrodynamic force simulation water outlet structure is a water flow tank (11) which is placed on the ground and used for simulating the surface water flow process, the water outlet of the water flow tank 11 is communicated with a plurality of water outlet pipes (10), and each water outlet pipe (10) is provided with a valve (5).
8. The experimental apparatus for analyzing the hydrodynamic stability characteristics of the subgrade slope according to the claim 7, wherein the number of the water outlet pipes (10) is 11, the diameter of the water outlet pipes is 4cm, and the distance between the water outlet pipes is 5 cm.
9. The experimental device for analyzing the hydrodynamic stability characteristics of the roadbed slope according to claim 1, wherein the liquid pressurizer (4) adopts an ORS25-10 type hydraulic pressure booster, the rated voltage is 220V-50Hz, the input/output power is 200W, the maximum flow is 3 tons/hour, and the pipe diameter is 4 minutes.
10. The experimental device for analyzing the hydrodynamic stability characteristics of the roadbed slope according to claim 1, wherein two flowmeters (6) adopt glass rotameters, wherein the measuring range of one flowmeter (6) is 25-250mL/min, and the measuring range of the other flowmeter (6) is 250-2000 mL/min.
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