A device for ensuring the accuracy of rainfall intensity of a geotechnical centrifuge

Abstract

The present application belongs to the technical field of soil centrifuge simulation rainfall test, and discloses a rainfall device for improved centrifugal model rainfall test. The rainfall device comprises a centrifugal box, a rainfall module and a fixing module. The rainfall module is arranged above the centrifugal box to simulate rainfall, and the fixing module is used for fixing the rainfall module above the centrifugal box. The rainfall module comprises a water source, an atomizer water pump and a water outlet unit connected by a water delivery pipe in sequence. The atomizer water pump is used for providing atomized water pressure in the water delivery pipe. The water outlet unit comprises a U-shaped water delivery pipe and a nozzle. The height of the inner wall of the top of the water inlet pipe of the U-shaped water delivery pipe is lower than the height of the inner wall of the bottom of the water outlet pipe, so as to prevent the water in the U-shaped pipe from overflowing to form a cavity. Through the present application, the problems of nozzle leakage, cavity in the pipe, rainfall delay and uneven distribution of rainfall on the surface of the soil under the combined action of gravity, Coriolis force and centrifugal force are solved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of geotechnical centrifuge simulation rainfall test, and more particularly relates to a device for ensuring the accuracy of rainfall intensity of a geotechnical centrifuge. BACKGROUND

[0002] Geotechnical centrifugal model test is to place a geotechnical model in a high-speed rotating centrifuge, so that the model is subjected to centrifugal acceleration N times the gravitational acceleration, compensating for the loss of self-weight stress of the model due to the scale of 1 / N, and the loss of weight stress reaches the same stress level as the prototype. It is closer to the actual situation than the physical simulation under the condition of static force (gravitational acceleration). According to the principle of modern relativity, gravity and inertial force are equivalent, and the basic physical and chemical properties of soil will not change with the change of acceleration. Therefore, the centrifugal simulation technology is particularly effective for soil structures that are mainly loaded by gravity.

[0003] At present, when simulating rainfall in a centrifugal field, a screen type or a spraying type rainfall device is usually used. The raindrops formed by this device are generally large (2.4mm-6.0mm). When they reach the surface of the rock-soil structure in the centrifugal field by centrifugal acceleration, they will form a large inertial force, which is easy to form a large splash and dynamic effect on the surface of the rock-soil structure, causing the test results to be seriously distorted. It is difficult to simulate the mechanical response of rock-soil structures under the influence of continuous rainfall. In addition, the above-mentioned rainfall device also faces the problem of limited adjustable range of rainfall intensity (generally only 2-4 different rainfall intensities can be simulated). The application number 201910617418.X discloses a simulation rainfall device and method for centrifugal model test. The number and layout spacing of the atomizing nozzles are set to realize rainfall, and the electromagnetic valve is controlled to start and stop. However, the atomizing nozzle and the electromagnetic valve are simply used to realize rainfall and avoid erosion. The influence of Coriolis force, resistance and artificial wind above the model on the rainfall effect in the centrifuge is not considered, and the water output of the nozzle is even seriously affected. It is particularly worth noting that the centrifugal inertia force in the model box is not strictly equivalent to gravity. The difference between the centrifuge stress field and the gravitational field is not only that the size changes with the radius, but also that the direction is radial. The equipotential lines are distributed in a fan shape with the center of rotation as the center (as shown in Figure 7 Figure 8 ​The parallel centrifugal force component causes the water in the water pipe to flow to the low structure, that is, the nozzle, and the common nozzle on the market can form droplets under liquid pressure, and the droplets accelerate under the centrifugal field, which causes the atomizing nozzle to leak when the electromagnetic valve is closed, the cavity is formed in the water pipe, the water pump cannot output the actual power, the effect of the next round of atomizing rainfall and the accuracy of the rainfall intensity are affected, and finally the test results have serious errors, it is difficult to calculate the real rainfall, and other problems. Especially for simulating multiple rounds of rainfall in one test, it means that the electromagnetic valve and the water pump need to be started and stopped multiple times, so the error value is multiplied by the number of starts and stops based on the single error, which greatly reduces the accuracy of the results. On the other hand, the rainfall intensity in the centrifugal field can be divided into two types, the first is the supply intensity of the nozzle, and the second is the actual receiving intensity of the surface in different regions. The sprayed droplets do not fall vertically as shown in Figure 9 but are scattered as shown in Figure 7 , and the precipitation on both sides of the model is higher than the middle, which causes the actual rainfall on the surface of the geotechnical structure and the amount of water sprayed through the nozzle to be inconsistent and unevenly distributed.

[0004] In summary, the existing rainfall devices do not consider that the centrifugal force and the gravity are not completely equivalent, the water pipe is completely placed horizontally, water leakage occurs, and then a cavity is formed in the pipe, which causes a delay in the next rainfall to fill the cavity and other problems. Therefore, even if the atomized droplets are under the action of external forces such as centrifugal force, it is difficult to uniformly distribute on the surface of the geotechnical structure. Therefore, to achieve the ideal atomizing rainfall effect and uniform distribution of rainfall, that is, stable output intensity and uniform receiving intensity, real-time monitoring of the rainfall intensity and the rainfall range also needs to be further improved. SUMMARY

[0005] In view of the above defects or improvement needs of the prior art, the present application provides a kind of atomizing nozzle rainfall device for centrifugal model rainfall test improvement, solve the problem of atomizing nozzle leakage, pipe cavity, rainfall delay and uneven distribution of mist droplets under the combined action of gravity, coriolis force and uneven distribution of centrifugal field.

[0006] To achieve the above purpose, according to the present application, a device for ensuring the accuracy of rainfall intensity of a geotechnical centrifuge is provided, which comprises a centrifugal box, a rainfall module and a fixing module, wherein,

[0007] The rainfall module is arranged above the centrifugal box and is used to rain on the centrifugal box, and the fixing module is used to fix the rainfall module above the centrifugal box.

[0008] The rainfall module comprises a water source, an atomizer water pump and a terminal water outlet unit connected in sequence through a water delivery pipe, the atomizer water pump is used for providing atomized water pressure in the water delivery pipe, the terminal water outlet unit comprises a U-shaped water delivery pipe and a nozzle, the nozzles are connected through right-angle terminals, the height of the inner wall of the top of the water inlet of the U-shaped water delivery pipe is lower than the height of the inner wall of the bottom of the water outlet, so as to avoid water overflow in the U-shaped pipe and form a cavity in the pipe.

[0009] Further preferably, the rainfall module comprises one or more terminal water outlet units connected through the water delivery pipe and the atomizer water pump.

[0010] Further preferably, the fixing module comprises a horizontal beam and a vertical beam, which fix the rainfall module in two directions in the horizontal plane.

[0011] Further preferably, the vertical beam is a guide rail of the horizontal beam, and the horizontal beam moves along the vertical beam to change the distribution of the rainfall module above the centrifugal tank.

[0012] Further preferably, the front end of the terminal water outlet unit is provided with a flow meter for calculating the rainfall of the terminal water outlet unit.

[0013] Further preferably, an electromagnetic valve is arranged between the water source and the atomizer water pump for controlling the start and stop of the rainfall module.

[0014] Further preferably, a flow meter is arranged between the atomizer and the electromagnetic valve for real-time monitoring of the water supply.

[0015] Further preferably, a filter screen is arranged in the water delivery pipe between the water source and the electromagnetic valve.

[0016] Further preferably, the bottom end of the centrifugal tank is provided with a runoff collection groove for collecting surface runoff that is not infiltrated on the slope.

[0017] Further preferably, the centrifugal tank is further provided with a calibration unit, which comprises a stepped platform and a water container arranged on the stepped platform, the water container is used for collecting rainfall on the surface of the geotechnical structure in a calibration stage to obtain the actual rainfall distribution, and the arrangement of the fixing module and the rainfall module is adjusted based on the actual rainfall distribution, so that the rainfall is evenly distributed. Overall, compared with the prior art, the above technical scheme of the present application has the following advantages

[0018] 1. The U-shaped water delivery pipe is adopted in the terminal water outlet unit in the present application, as shown in Figure 6As shown, the height of the inner wall of the outlet pipe bottom of the water pipe is slightly higher than the height of the inner wall of the top of the inlet pipe, and the liquid level above the dotted line will overflow a small part due to the action of the centrifugal inertial force oblique to the surface of the model box, and under the action of the parallel force, but this part of the water and the cavity formed by the overflow are negligible compared to the water and the cavity in the entire water pipe, which will not seriously affect the test results and the subsequent rainfall intensity, and this part of the error can be calculated and quantified, and is within the acceptable error range; and the water in the pipe below the dotted line in the figure cannot overflow because it is laterally limited by the pipe wall in the parallel direction and cannot form a liquid level difference with the left water pipe in the vertical direction, i.e. there is no pressure difference, so it will not overflow, ensuring the stable supply of water in the pipe and preventing excessive dripping and time delay caused by the formation of a cavity.

[0019] 2. The present application is based on the water distribution in the stepped water container, and changes the distribution law of the nozzle by moving the cross beam to control the density and horizontal and vertical spacing of the nozzle, and ultimately realizes uniform rainfall on the surface of the geotechnical structure. In addition, it can also realize differential rainfall between regions by changing the nozzle spacing, providing convenience for different test conditions. At the same time, since the size and spacing of the water containers on each step are consistent, i.e. the water holding area per unit area is fixed, the rainfall in the corresponding area of each step can be calculated by the water holding capacity of the water container, and the actual rainfall intensity of each region in the test can be reflected.

[0020] 3. The present application can monitor the flow in real time, calculate the rainfall at the nozzle, and control the actual rainfall received by the surface of the geotechnical structure, so as to better control the test process and results, and keep the test error within an acceptable range. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 is a structural schematic diagram of the atomizing nozzle rainfall device for centrifugal model rainfall test improvement according to the preferred embodiment of the present application;

[0022] Figure 2 is a top view of the atomizing nozzle rainfall device for centrifugal model rainfall test improvement according to the preferred embodiment of the present application;

[0023] Figure 3 is a front view of the atomizing nozzle rainfall device for centrifugal model rainfall test improvement according to the preferred embodiment of the present application;

[0024] Figure 4 is a structural schematic diagram of the rainfall module according to the preferred embodiment of the present application;

[0025] Figure 5 is a front view of a rainfall module constructed in accordance with a preferred embodiment of the present application;

[0026] Figure 6 is a schematic diagram of a U-shaped water pipe structure constructed in accordance with a preferred embodiment of the present application;

[0027] Figure 7 is a schematic diagram of the direction of centrifugal force, the equipotential line distribution and the actual falling trajectory of the fog droplets, constructed in accordance with a preferred embodiment of the present application;

[0028] Figure 8 is a schematic diagram of the force acting on a common water pipe and nozzle, constructed in accordance with a preferred embodiment of the present application;

[0029] Figure 9 is a schematic diagram of the falling trajectory of the fog droplets in an ideal case, constructed in accordance with a preferred embodiment of the present application;

[0030] Figure 10 is a schematic diagram of a 45° slope calibration system and water collecting box distribution, constructed in accordance with a preferred embodiment of the present application.

[0031] In all the drawings, the same reference numerals are used to denote the same elements or structures, in which:

[0032] 1 - water source, 2 - water pipe, 3 - filter screen, 4 - electromagnetic valve, 5 - flow meter, 6 - atomizer water pump, 7 - U-shaped water pipe, 8 - nozzle, 9 - water tank support rod, 10 - cross beam, 11 - vertical beam, 12 - centrifugal tank, 13 - water collecting box, 14 - grading step, 15 - runoff collection tank DETAILED DESCRIPTION

[0033] In order to make the objectives, technical solutions and advantages of the present application clearer, further detailed description will be made to the present application in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application, and are not used to limit the present application. In addition, the technical features involved in each embodiment of the present application described below can be combined with each other as long as there is no conflict.

[0034] As shown in Figures 1-3 , a nozzle rainfall device for improving centrifugal model rainfall test includes an external water tank / water source 1, a water pipe 2, a filter screen 3, an electromagnetic valve 4, a flow meter 5, an atomizer water pump 6, a U-shaped water pipe 7, a nozzle 8, a water tank support rod 9, a cross beam 10, a vertical beam 11, a binding belt not marked in the diagram, flexible arrangement, a centrifugal tank 12, a water collecting box 13, a grading step 14 and a runoff collection tank 15.

[0035] As shown in Figure 4 and 5As shown, the water pipe 2 is connected to the bolt hole reserved in the water tank 1, a filter screen 3 is installed at the other end of the water pipe, and is connected to the electromagnetic valve 4, then the water pipe 2 is connected to the flow meter 5, the sprayer water pump 6, the U-shaped water pipe 7, and the nozzle 8 in sequence, the U-shaped water pipe 7 is connected to the nozzle 8 through a right-angle terminal, then is fixed to the cross beam 10 through a binding belt, and the cross beam 10 is fixed to the vertical beam 11 through a bolt. The stepped platform 14 is arranged at the bottom of the centrifugal tank before the rainfall calibration, and a plurality of water containers 13 are arranged at equal intervals on the platform for containing the water of the nozzles, Figure 9 As shown, the runoff collection groove 15 is used to collect the surface runoff on the slope surface which is not infiltrated.

[0036] In the embodiment, the external water source 1 is a water tank, the size of the water tank is 1m*0.25m*0.2m, the length is 1m, the width is 0.25m, and the depth is 0.2m, and the water tank is divided into 0.2m grooves, the bottom between the grooves is punched for water passing, after water is added, 1-2 water pressure sensors can be placed and connected to the numerical control machine tool, so that the water level change in the water tank is recorded in real time through the change of the water pressure, and the data of the flow meter at the nozzle is compared to judge whether the rainfall intensity is consistent, so as to observe whether there is water leakage in the rotation process, whether there is air cavity formed in the water pipe, and to reduce the probability of water leakage due to slight deformation of the material in a high pressure environment, only one threaded water outlet hole is arranged.

[0037] The water pipe 2 adopts a common transparent high-strength PU pipe on the market, the specification model is PU12X8mm, the outer diameter is 12mm, the inner diameter is 8mm, the working pressure is 1Mpa, and the burst pressure is 3Mpa, and the working temperature is-30~60℃.

[0038] The filter screen 3 selects a 200-mesh nylon screen for filtering small impurities in the water, preventing the nozzle from being blocked during the rainfall process, effectively ensuring the atomization effect, ensuring that the rainfall intensity is not affected, and finally ensuring the accuracy of the test results.

[0039] The electromagnetic valve 4 adopts SAN YE 2W-160-10AC220V, the diameter is 10mm, the allowable pressure is 10Mpa, and the allowable medium temperature is-5~80℃, which is used to control the start and stop of the rainfall together with the water pump.

[0040] The flow meter 5 is a impeller type flow meter, the inner diameter is 10mm, the flow range is 0.2~1.5m 3 / h, the maximum pressure is 6.3Mpa, and is provided with front and rear straight pipe sections and a filter, which can be connected to the numerical control machine tool of the centrifuge to monitor the flow size in real time.

[0041] The sprayer water pump 6 selects a tiger leap electric sprayer water pump HY-5800, the maximum pressure is 0.8Mpa, the flow capacity is 5.0L / min, the inlet size is 10mm, and is used together with the nozzle to achieve the atomization effect.

[0042] U-shaped water delivery pipe 7 is connected between the pump and the nozzle, and the liquid level at the nozzle connection is slightly higher than that at the atomizer water pump connection, as shown in the figure, the purpose is to just use this liquid level difference in a larger centrifugal acceleration field, and to lock most of the water in the pipe under the action of the vertical component of the centrifugal force, as shown in the figure, so as to avoid affecting the accuracy of the rainfall intensity and the test results, and to ensure that sufficient water source and water pressure are provided for the nozzle 8 during the pressure application of the atomizer water pump 6. Figure 6 Figure 6

[0043] The nozzle 8 is an FN nozzle, the nozzle aperture is 0.46mm, and very fine droplets can be generated only by using liquid pressure by relying on unique internal vortex blades, the average particle diameter is only 40 microns, the minimum atomization particle size can reach 20 microns, and the spray shape is a 60° solid conical shape under a pressure of 7bar, and the atomization effect is very uniform.

[0044] The stepped platform 14 can pour concrete platforms of different heights according to different test sites, and the implementation of the present application takes a 45° slope as an example, as shown in the figure, which is a 45° slope rainfall calibration arrangement. The water containers 13 are evenly distributed on the platform, and the actual rainfall intensity and distribution of the slope surface can be determined by the weight change before and after and the amount of water in each water container, so as to adjust the layout of the fixed module and the rainfall module. The runoff collection tank 15 is used to collect runoff that cannot be infiltrated on the slope surface, to prevent water accumulation at the slope foot. Figure 10

[0045] The method for simulating rainfall by the above-mentioned rainfall simulation device is as follows:

[0046] First step: layout of water delivery and precipitation system: connect the bolt holes reserved in the external water tank through the water delivery pipe, install a filter screen at the other end of the water delivery pipe, and connect it to the electromagnetic valve, then connect the atomizer water pump, flow meter, U-shaped water delivery pipe, nozzle in sequence through the water delivery pipe, connect the U-shaped water delivery pipe terminal with the atomizing nozzle, and then fix it with the cross beam by binding with a binding belt.

[0047] Second step: calibrate the rainfall intensity corresponding to different pump pressures of the atomizing nozzle under a specific acceleration field, the actual rainfall amount and radiation distribution range of the geotechnical structure surface, and test the working condition of the equipment in the centrifugal field. The following takes a 50g acceleration field and simulates a 45° slope rainfall at the slope foot as an example: four platforms are built at the bottom of the centrifugal tank, corresponding Figure 10 ​​​Platforms 1-5 are used to collect rainfall distribution data on a 45° slope. Five steps are constructed using concrete blocks, with a 5cm height difference between each step, simulating a 40cm high slope model and the rainfall distribution within a centrifuge. Several identical water containers are arranged at equal intervals on each step. Each water container is pre-numbered and weighed, totaling 80 water containers. Each water container is numbered and weighed before placement. A certain weight of water is added to the external water tank, and the final water level should not exceed 80% of the tank's height.

[0048] First, before starting the centrifuge, start the solenoid valve and sprayer water pump to fill the water pipe with water and remove the air from the pipe. Use a container to catch the water droplets at the nozzles and observe the atomization of each nozzle to see if there is any blockage or water column phenomenon. If the atomization effect is good, turn off the solenoid valve and sprayer water pump, pour the water in the container into the water tank, weigh the water level, and seal the tank to prevent water from overflowing and evaporating.

[0049] Then, start the centrifuge to accelerate to 50g, activate the solenoid valve and sprayer pump, and simultaneously record the changes in the flow meter readings on the water delivery pipe and the water pressure sensor readings in the water tank, fed back from the centrifuge's control panel. Record the relationship between pump pressure, water pressure, and flow rate for each start-stop cycle. Using the same pump pressure, perform 3-5 start-stop cycles to test whether the rainfall intensity fluctuates significantly. If the flow rate fluctuations in each start-stop cycle are within acceptable limits, it indicates that the rainfall intensity is relatively stable and there are no leaks or blockages. Figure 2 As shown, flow meter 5 is used to record changes in flow rate within the water supply system. It can be connected to the CNC machine tool of the centrifuge via a data cable, reflecting flow changes in real time in the monitoring room. Wired transmission is more stable and reliable than wireless transmission in the high-speed rotating centrifuge field. The change in flow rate during the rainfall cycle is recorded as rainfall intensity 1. Before the experiment begins, in... Figure 4 Two pore pressure sensors are placed in the water tank 1 shown. The water tank can be divided into 5 water tanks, which are connected by holes. This ensures that the water level changes in each tank are synchronized. The water level changes are directly recorded by the two pore pressure sensors, and the pore pressure drop data is recorded by a CNC machine tool. The changes in pore pressure are reflected in real time on the monitoring screen. Since the cross-sectional area of ​​the water tank, the density of water, the centrifugal acceleration, and the descent time are known, the rainfall intensity per unit time can be calculated and denoted as rainfall intensity 2. At the same time, the water content in the water pipe and the operation of the nozzles are observed through a high-definition camera. In addition to observing the operation of the instruments when they are turned on, special attention should be paid to whether the nozzles drip or leak during the interval from the end of the current rainfall to the start of the next operation, and whether the flow count value changes.

[0050] Finally, the same pump pressure value to be experienced 3-5 start-stop cycle, centrifuge shutdown after recording each level of the rainwater in the box, according to the rainfall period, interval time, each level of the rainwater in the box area and the ratio of the step area to calculate the actual rainfall intensity 3; according to the weight of each rainwater in the box to determine the distribution of the surface rainfall, easy to adjust the nozzle horizontal and vertical spacing and nozzle density; after shutdown, measure the actual water level drop value, because the water tank bottom area is known, the density and gravity acceleration is known, by water level difference can calculate the water change value, and combined with the rainfall period and time to obtain the rainfall intensity 4; the water tank and the water pipe remaining water is poured out, weighing and with the total water added before the centrifuge to difference value, according to the total rainfall time and interval number to calculate the total rainfall intensity 5.

[0051] Third step: can be monitored by flow meter and water tank hole pressure sensor value changes in real time, and can convert the rainfall intensity 1, 2 size. In the ideal case, the rate of change in each cycle should be fixed, if there is a large jitter, indicating that the water supply system and the rainfall system appears cavity need to stop test immediately, equipment correction. Calibration process to calculate the rainfall intensity 3 value can reflect the actual rainfall intensity of each region of the geotechnical structure surface, as a reference, by moving the beam to change the nozzle distribution law, control nozzle density and horizontal and vertical spacing. Rainfall intensity 4 and 5 data for checking the actual total rainfall intensity, can reflect the total water change value, generally more accurate and reliable. After the test, the data of 4, 5 combined with the runoff collection tank 15 in the water storage capacity, to calculate the slope infiltration and slope runoff, so as to obtain the soil permeability under the centrifugal acceleration field, also can provide reliable parameters for the post-processing process.

[0052] The transverse comparison of total rainfall intensity 1-5 data to determine the final rainfall intensity, generally speaking, the rainfall intensity 1 and 2 value should be approximately equal; the value of rainfall intensity 1 will be higher than the value of rainfall intensity 3; the value of rainfall intensity 3 is less than the value of rainfall intensity 4; the value of rainfall intensity 5 may be slightly greater than the value of 4. If the 5 data is not much different, the average value can be taken as the rainfall intensity under the given acceleration field and the given pump pressure, generally speaking, the data of rainfall intensity 3 can be used as the actual rainfall intensity distribution data, that is, the actual rainfall intensity of the test condition. According to the intuitive judgment of the water level in the rainwater in the box, the distribution law of each region is determined. The rainfall system is attached to the beam, so the distribution law of the nozzle is changed by moving the beam, the density and horizontal and vertical spacing of the nozzle are adjusted, and finally the uniform rainfall on the surface of the geotechnical structure is realized.

[0053] Those skilled in the art can easily understand that the above description is only the preferred embodiment of the present application, and is not intended to limit the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A device for ensuring the accuracy of rainfall intensity in a geotechnical centrifuge, characterized by, The device comprises a centrifugal tank (12), a rainfall module and a fixing module, wherein, the rainfall module is arranged above the centrifugal tank and is used to provide rainfall to the centrifugal tank (12), and the fixing module is used to fix the rainfall module above the centrifugal tank; the rainfall module comprises a water source (1), an atomizer water pump (6) and a terminal water outlet unit connected in sequence through a water delivery pipe, the atomizer water pump (6) is used to provide atomized water pressure in the water delivery pipe (2), and the terminal water outlet unit comprises a U-shaped water delivery pipe (7) and a nozzle (8), the nozzles (8) are connected through right-angle terminals, and the height of the inner wall of the top of the inlet of the U-shaped water delivery pipe (7) is lower than the height of the inner wall of the bottom of the outlet, so that the water in the U-shaped pipe is prevented from overflowing to form a cavity in the pipe; the rainfall module comprises one or more terminal water outlet units connected through the water delivery pipe and the atomizer water pump; the front end of the terminal water outlet unit is provided with a flow meter (5) for calculating the rainfall of the terminal water outlet unit; an electromagnetic valve (4) is arranged between the water source (1) and the atomizer water pump (6) and is used to control the start and stop of the rainfall module; a flow meter (5) is arranged between the atomizer water pump (6) and the electromagnetic valve (4) and is used to monitor the water supply in real time; a filter screen (3) is arranged in the water delivery pipe between the water source (1) and the electromagnetic valve (4).

2. The device for ensuring the accuracy of rainfall intensity of a geotechnical centrifuge according to claim 1, characterized in that, The fixing module comprises a cross beam (10) and a vertical beam (11), and the cross beam (10) and the vertical beam (11) fix the rainfall module in two directions in the horizontal plane.

3. A device for ensuring the accuracy of rainfall intensity of a geotechnical centrifuge according to claim 2, characterized in that, The vertical beam (11) is a guide rail of the cross beam (10), the cross beam (10) moves along the vertical beam (11), and the distribution of the rainfall module above the centrifugal tank is changed in sequence.

4. The device for ensuring the accuracy of rainfall intensity of a soil centrifuge according to claim 1, characterized in that, The bottom end of the centrifugal tank (12) is provided with a runoff collection groove (15) for collecting surface runoff that is not infiltrated on the slope.

5. The device for ensuring the accuracy of rainfall intensity of a geotechnical centrifuge according to claim 1, characterized in that, The centrifugal tank (12) is further provided with a calibration unit, the calibration unit comprises a stepped platform (14) and a water container (13) arranged on the stepped platform, the water container (13) is used to collect rainfall on the surface of the geotechnical structure in a calibration stage, so as to obtain the actual rainfall distribution and adjust the arrangement of the fixing module and the rainfall module according to the actual rainfall distribution, so as to achieve the purpose of uniform distribution of rainfall.

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