A mud anti-sedimentation device under hypergravity conditions and reliability verification method

Abstract

The present invention discloses a mud anti-sedimentation device under hypergravity conditions and a reliability verification method. The model box is used to store mud, a sealing baffle is connected to the top of the model box, a stirring assembly extends into the mud to stir the mud, and a monitoring assembly is arranged inside the model box to monitor the sedimentation of the mud and the working condition of the stirring assembly during the test; the mud anti-sedimentation device is placed on a geotechnical centrifuge, and the device is electrically connected to a control center in the geotechnical centrifuge; the stirring main shaft of the stirring motor passes through a stirring through hole on the side wall of the model box and then extends into the mud, and the stirring blades are installed on the periphery of the stirring main shaft, and the inclination angle of the stirring blades on the stirring main shaft is related to the direction of hypergravity to which the mud particles are subjected. The present invention proposes a reliability verification method for a monitoring assembly and a stirring assembly under hypergravity conditions, which can prevent the mud in the model box from being separated and precipitated under hypergravity conditions, and ensure the authenticity of the hypergravity physical model test simulating actual working conditions.

Description

Technical Field

[0001] The invention belongs to the field of hypergravity model tests, and in particular relates to a mud anti-sedimentation device under hypergravity conditions and a reliability verification method. Background Art

[0002] With the gradual implementation of the national regional economic integration and national large-channel construction plan, China has built a number of large-diameter underground tunnels in cities such as Shanghai, Nanjing, and Hangzhou. In these projects, slurry shields are widely used due to their ease of construction and precise control of support pressure. Slurry shields use pressurized mud to form a water-impermeable mud film on the excavation surface to support the strata ahead. However, with the continuous expansion of tunnel construction, shield tunnels continue to encounter complex geological conditions such as high water pressure and strong permeability. Slurry shield construction often faces technical challenges such as excavation face instability, stratum disturbance, and surface settlement. Therefore, conducting experimental research on slurry shields is of great significance to improving engineering safety and construction efficiency.

[0003] In order to explore the instability mechanism of the excavation face of the slurry shield and its stratum response mechanism, the geotechnical centrifuge technology provides corresponding research conditions. This technology generates a centrifugal acceleration n times the strength of the normal gravity field through high-speed rotation, and can restore the effective stress field of the real scale on the scaled slurry shield model and the stratum model. During the slurry shield test, a model box is required to store mud, and inlet and outlet pipes are provided to realize the injection and discharge of mud. However, the mud is prone to stratification under hypergravity conditions, resulting in low mud density in the upper part of the model box and high mud density in the lower part, which seriously affects the authenticity of the actual working conditions simulated by the hypergravity physical test. At the same time, the geotechnical centrifuge will generate interference magnetic fields and additional stresses during high-speed rotation, which will affect the electrical signal transmission capacity and bearing capacity of some electronic components. In addition, the applicability of the calibration results of various electronic components under normal gravity conditions under hypergravity conditions is unknown. If it is directly used in the hypergravity test, its accuracy and credibility are difficult to guarantee. Summary of the invention

[0004] In order to solve the problems existing in the background technology, the purpose of the present invention is to provide a mud anti-sedimentation device under supergravity conditions and a reliability verification method.

[0005] The technical solution adopted by the present invention is as follows:

[0006] 1. A mud anti-sedimentation device under super gravity conditions:

[0007] It includes a model box, a sealing partition, two sets of stirring components and a monitoring component; the model box is an internal hollow structure with an open top and a closed bottom, the model box is used to store mud, the sealing partition is connected to the top of the model box, one end of the stirring component extends into the mud stored in the model box and is used to stir the mud, and the monitoring component is arranged inside the model box for real-time monitoring of the sedimentation of the mud and the working condition of the stirring component during the test; the mud anti-sedimentation device is placed on the geotechnical centrifuge, and the device is electrically connected to the control center in the geotechnical centrifuge.

[0008] The two groups of stirring components are arranged at intervals along the height direction of the model box, and the two groups of stirring components are arranged horizontally along the long side direction of the model box. Each group of stirring components includes a stirring motor and a plurality of stirring blades. Two stirring through holes are opened on the side wall of the model box, and the shell of the stirring motor is fixedly connected to the side wall of the model box. The stirring main shaft of the stirring motor passes through the stirring through holes on the side wall of the model box and extends into the mud. A plurality of stirring blades are connected to the stirring main shaft at intervals along the axial direction of the stirring main shaft.

[0009] The monitoring component includes a photoelectric velocimeter, three ultrasonic densitometers and two cameras; the photoelectric velocimeter is connected to the lower surface of the sealing partition and is used to monitor the rotation speed of the stirring motor in real time; three monitoring holes at different heights are opened on the outer wall of the model box, and the probes of the three ultrasonic densitometers are respectively passed through the three monitoring holes and extended into the mud, and the ultrasonic densitometers are used to record the density of the mud at different heights in the model box in real time; two cameras are respectively installed on the stirring spindles of the two stirring motors, and the cameras are used to verify the reliability of the photoelectric velocimeter under ultra-gravity conditions.

[0010] Each circle of stirring blades is mainly formed by a plurality of stirring blades evenly spaced along the circumference of the stirring main shaft. The stirring blades in the same circle are located on the same plane. The extension direction of the plane where each circle of stirring blades is located is the direction of the centrifugal force exerted on the stirring blades in the supergravity environment.

[0011] The model box is arranged with six vertical grilles and three horizontal grilles on both sides of the long sides, and three horizontal grilles on one side of the short sides. No grilles are arranged on the other side of the short side of the model box. The grilles are used to improve the strength of the model box and prevent the model box from deformation or damage in a hypergravity environment.

[0012] The geotechnical centrifuge comprises a first hanging basket, a second hanging basket, a centrifuge base and a control center; the first hanging basket and the second hanging basket are fixedly installed on both sides of the centrifuge base through a rotating arm respectively, a counterweight is placed inside the first hanging basket, a mud anti-sedimentation device is fixedly installed on the second hanging basket, a cable is provided on the rotating arm connecting the second hanging basket and the centrifuge base, and a photoelectric velocimeter, an ultrasonic densitometer and a camera are all connected to the control center through the cable; the control center is used to obtain the density of the mud, the speed of the stirring motor and the rotation image of the stirring motor during the test.

[0013] 2. A reliability verification method for monitoring components under hypergravity conditions, comprising the following steps:

[0014] Step 1. Check the tightness of the device: Fill the model box with water, use a glass hydrometer to test the density of the water in the model box, turn on the stirring motor and continue stirring for 10 minutes. During the stirring process, check the water sealing of each device and interface:

[0015] If the sealing condition of each instrument is good, proceed to step 2;

[0016] Otherwise, reassemble the device until all equipment in the device are well sealed;

[0017] Step 2, obtaining the maximum speed n of the stirring motor: start the stirring motor and set the speed of the stirring motor to 1 r / min, and gradually increase the speed of the stirring motor in increments of 1 r / min. When the camera cannot recognize the stirring motor, the speed of the stirring motor at this time is recorded as n+1 r / min, where n is the maximum speed of the stirring motor;

[0018] Step 3, install the entire device in the second hanging basket of the geotechnical centrifuge and ensure the stability of the device installation; after the device is placed stably, under normal gravity conditions, turn on the stirring motor and set the speed of the stirring motor to the maximum speed n;

[0019] Step 4, start the geotechnical centrifuge, increase the acceleration of the geotechnical centrifuge, and after the acceleration reaches the target Ng value, maintain the Ng value for 30 minutes. During the process of maintaining a stable Ng value, record the ultrasonic densitometer indication, the photoelectric velocimeter indication, and the stirring motor speed recognized by the camera every 10 minutes;

[0020] Step 5: Compare the ultrasonic densitometer indication, photoelectric velocimeter indication and stirring motor speed identified by the camera recorded during the test with the density of water under constant gravity and the set stirring motor speed to verify the reliability of the monitoring component.

[0021] Step 5.1. Compare the ultrasonic density meter reading during the test with the density of water under normal gravity to verify the reliability of the ultrasonic density meter:

[0022] If the indication on the ultrasonic density meter is the same as that on the glass hydrometer, it means that the ultrasonic density meter works normally in the hypergravity environment and the reliability verification is qualified;

[0023] Otherwise, it indicates that the ultrasonic density meter fails in the hypergravity environment and the reliability verification fails. The ultrasonic density meter is corrected according to the difference between the indication of the ultrasonic density meter and the indication of the glass hydrometer;

[0024] Step 5.2: Compare the stirring motor speed identified by the camera during the test with the stirring motor set speed n to verify the reliability of the stirring motor:

[0025] If the error between the stirring motor speed identified by the camera and the set maximum speed n is within 5%, it indicates that the stirring motor works normally in the hypergravity environment, the reliability verification is qualified, and the process goes to step 5.3;

[0026] Otherwise, it indicates that the stirring motor fails in the hypergravity environment and the reliability verification fails. The stirring motor is replaced and the reliability verification of the stirring motor is performed again in the hypergravity environment until the reliability verification of the stirring motor passes.

[0027] Step 5.3: Compare the photoelectric tachometer indication during the test with the qualified stirring motor speed identified by the camera to verify the reliability of the photoelectric tachometer:

[0028] If the value indicated by the photoelectric velocimeter is consistent with the qualified stirring motor speed identified by the camera, it means that the photoelectric velocimeter works normally in the hypergravity environment and the reliability verification is qualified;

[0029] Otherwise, it indicates that the photoelectric velocimeter fails in the hypergravity environment and the reliability verification fails. The photoelectric velocimeter is corrected according to the difference between the indication of the photoelectric velocimeter and the stirring motor speed recognized by the camera.

[0030] 3. A reliability verification method for the anti-sedimentation effect of the stirring assembly mud under hypergravity conditions, comprising the following steps:

[0031] Step 1: Prepare Bentonite Slurry

[0032] The bentonite particles, sodium carboxymethyl cellulose (CMC) and water are mixed in a preset ratio and stirred thoroughly. After stirring, the mixture is allowed to stand for more than 24 hours to obtain a bentonite slurry. When no precipitation is observed in the bentonite slurry, the density of the bentonite slurry is measured using an ultrasonic densitometer as the calibrated density of the slurry.

[0033] Step 2: Check the tightness of the device

[0034] Assemble the entire device under normal gravity conditions, then fill the model box with mud, turn on the stirring motor for 10 minutes, and check the water sealing conditions of each device and interface during the stirring process:

[0035] If the sealing condition of each instrument is good, proceed to step 3;

[0036] Otherwise, reassemble the device until all equipment in the device are well sealed;

[0037] Step 3: Install the entire device in the second hanging basket of the geotechnical centrifuge and ensure the stability of the device installation; after the device is placed stably, under normal gravity conditions, turn on the stirring motor to stir the bentonite slurry in the model box and set the speed of the stirring motor to 40r / min;

[0038] Step 4: Start the geotechnical centrifuge and increase its acceleration. After the acceleration reaches the target Ng value, maintain the Ng value for 30 minutes. While maintaining a stable Ng value, verify the anti-sedimentation effect of the mixing assembly based on the real-time mud density.

[0039] In step 4, the mud anti-sedimentation effect of the stirring assembly is verified according to the mud density, and the following steps are specifically adopted: after the centrifugal acceleration Ng value is stable, the density of the mud at different heights is recorded every 10 minutes and compared with the mud calibration density under normal gravity, etc.:

[0040] If the difference between the ultrasonic density meter indication and the mud calibration density under normal gravity is within the preset range, it indicates that the mud anti-sedimentation effect of the stirring assembly is qualified at the current speed;

[0041] Otherwise, it indicates that the mud anti-sedimentation effect of the stirring assembly is unqualified at the current speed. The stirring assembly should be replaced or the speed of the stirring motor should be increased until the mud anti-sedimentation effect of the stirring assembly is qualified.

[0042] The principle of stratification of mud under supergravity conditions in the present invention is as follows:

[0043] Under normal gravity conditions:

[0044] The specific gravity of the solid phase in the mud is γ1=ρ solid The specific gravity of the liquid phase in the g mud is γ2 = ρ liquid ·g

[0045] Buoyancy coefficient Δρg=(ρ solid -ρ liquid )·g

[0046] Under N times hypergravity conditions:

[0047] The specific gravity of the solid phase in the mud is γ3=N·ρ solid·g

[0048] The specific gravity of the liquid phase in the mud is γ4 = N·ρ liquid ·g

[0049] Buoyancy coefficient N·Δρg=N·(ρ solid -ρ liquid )·g

[0050] Among them, ρ solid , liquid They represent the density of the solid phase and liquid phase in the mud respectively; g represents the acceleration due to gravity; N represents the ratio of the centrifugal acceleration of the geotechnical centrifuge to the acceleration due to gravity;

[0051] The average particle size of bentonite particles in the mud is about 10μm, and the sedimentation in the mud is mainly affected by gravity. Under the action of N times hypergravity, the gravity of the mud particles increases by N times, and the buoyancy coefficient also increases by N times, which increases the relative motion driving force between materials of different density phases, and the bentonite particles in the model box will be more likely to precipitate.

[0052] The high gravity conditions are created by the high speed rotation of the geotechnical centrifuge:

[0053] The super gravity on the mud particles in the model box is Ng = ω 2 ·R

[0054] Among them, ω is the angular velocity of the geocentrifuge, and R is the distance from the mud particle to the rotation center of the geocentrifuge. Therefore, the magnitude and direction of the supergravity exerted on the mud particles at different positions are different. Therefore, it is necessary to set stirring blades with different angles at different positions to better achieve the anti-sedimentation effect of the mud particles.

[0055] The principle of the photoelectric velocimeter in the present invention is as follows:

[0056] The speed of the stirring motor is RPM = 60 / (i·T)

[0057] Where i is the number of stirring blades in each group; T is the time interval between occlusion events;

[0058] The principle of the photoelectric tachometer to measure the motor speed is based on the photoelectric sensor in the photoelectric tachometer detecting the stirring blades installed on the stirring main shaft of the stirring motor. When the stirring blades pass through the photoelectric sensor, they block the light. After receiving the light and sensing its changes in brightness, the photoelectric sensor outputs a current pulse signal. By recording the time interval T between these blocking events, the photoelectric tachometer can calculate the speed of the stirring motor.

[0059] The device of the present invention includes a mud anti-sedimentation device and a geotechnical centrifuge. The mud anti-sedimentation device is placed in the second hanging basket of the geotechnical centrifuge, and the rotation speed of the geotechnical centrifuge arm is gradually increased to provide supergravity conditions for the mud anti-sedimentation test. At the same time, a method for verifying the reliability of the mud anti-sedimentation device under supergravity conditions is proposed, which includes a reliability verification method for a monitoring component under supergravity conditions and a verification method for the mud anti-sedimentation effect of a stirring component under supergravity conditions.

[0060] The beneficial effects of the present invention are:

[0061] 1. Hypergravity conditions easily lead to the sedimentation of particles in the mud, and the directions of hypergravity at different positions in the model box are different. The present invention drives the stirring blades to stir the mud in the model box by a stirring motor, and sets the inclination angle of the stirring blades according to the direction of hypergravity experienced by the particles in the mud, which can better prevent the sedimentation of particles in the mud.

[0062] 2. The present invention arranges three ultrasonic densitometers in the model box, which penetrate into the mud at different heights respectively, and can monitor the stratification of the mud in the model box in real time. In order to deal with the interference of the magnetic field and the additional stress on electronic components under hypergravity conditions, the present invention proposes a reliability verification method for monitoring components under hypergravity conditions and a verification method for the mud anti-sedimentation effect of stirring components under hypergravity conditions.

[0063] 3. The present invention provides the test conditions and test methods for mud replenishment for the hypergravity physical test research on the instability and destruction of the excavation face and the stratum disturbance mechanism during the slurry shield tunneling process. Under the effect of the time and scale reduction effect of the geotechnical centrifuge, it provides engineering guidance for the construction of deep underground and deep sea tunnels. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] Figure 1 It is a front view of the model box and the mud anti-sedimentation stirring device of the present invention;

[0065] Figure 2 It is a side cross-sectional view of the model box and the mud anti-sedimentation stirring device of the present invention;

[0066] Figure 3 It is a side view of the model box and the mud anti-sedimentation stirring device of the present invention;

[0067] Figure 4 This is a schematic diagram of the structure of the stirring blade of the present invention;

[0068] Figure 5 It is a schematic diagram of the structure of the geotechnical centrifuge of the present invention.

[0069] In the figure: 1. model box; 2. sealing partition; 3. stirring motor; 4. stirring blade; 5. stirring main shaft; 6. grille; 7. photoelectric tachometer; 8. ultrasonic densitometer; 9. camera; 10. geotechnical centrifuge; 101. first hanging basket; 102. counterweight; 103. second hanging basket; 104. rotating arm; 105. cable; 11. control center; 12. fixing bolt; 13. protective cover. DETAILED DESCRIPTION

[0070] The present invention is described in detail below in conjunction with specific implementation cases. The following implementation cases will help those skilled in the art to further understand the present invention, but will not limit the present invention in any form.

[0071] like Figure 1 As shown, the device includes a model box 1, a sealing baffle 2, two sets of stirring components and a monitoring component; the model box 1 is an internal hollow structure with an open top and a closed bottom, the model box 1 is used to store mud, the sealing baffle 2 is connected to the top of the model box 1, one end of the stirring component extends into the mud stored in the model box 1 and is used to stir the mud, and the monitoring component is arranged inside the model box for real-time monitoring of the sedimentation of the mud and the working condition of the stirring component during the test; the mud anti-sedimentation device is placed on the geotechnical centrifuge 10, and the device is electrically connected to the control center 11 in the geotechnical centrifuge 10.

[0072] like Figure 3 As shown, two groups of stirring components are arranged at intervals along the height direction of the model box 1, and both groups of stirring components are arranged horizontally along the long side direction of the model box 1. Each group of stirring components includes a stirring motor 3 and a plurality of stirring blades 4. Two stirring through holes are opened on the side wall of the model box 1, and the shell of the stirring motor 3 is fixedly connected to the side wall of the model box 1. The stirring main shaft 5 of the stirring motor 3 passes through the stirring through holes on the side wall of the model box 1 and extends into the mud. A plurality of stirring blades 4 are connected to the stirring main shaft 5 by fixing bolts 12 and are arranged at intervals along the axial direction of the stirring main shaft 5.

[0073] like Figure 2As shown, the monitoring component includes a photoelectric velocimeter 7, three ultrasonic densitometers 8 and two cameras 9; the photoelectric velocimeter 7 is connected to the lower surface of the sealing partition 2, and is used to monitor the rotation speed of the stirring motor 3 in real time; three monitoring holes at different heights are opened on the outer wall of the model box 1, and the three monitoring holes are in the same straight line. The probes of the three ultrasonic densitometers 8 are respectively passed through the three monitoring holes and extended into the mud. The ultrasonic densitometer 8 is fixed on the outer wall of the model box 1, and the ultrasonic densitometer 8 and the stirring component are staggered at the height of the model box 1 and do not contact. The ultrasonic densitometer 8 is used to record the density of the mud at different heights in the model box 1 in real time; two cameras 9 are respectively installed on the stirring spindles 5 of the two stirring motors 3, and the cameras 9 are used to verify the reliability of the photoelectric velocimeter 7 under supergravity conditions.

[0074] A protective cover 13 is provided at one end of the photoelectric velocimeter 7 and the ultrasonic densitometer 8 extending into the model box 1 to reduce the influence of the high-speed stirring mud inside the model box 1 on the test results.

[0075] like Figure 4 As shown, each circle of stirring blades 4 is mainly formed by a plurality of stirring blades 4 evenly spaced along the circumference of the stirring main shaft 5. The stirring blades 4 of the same circle are located on the same plane. The extension direction of the plane where each circle of stirring blades 4 is located is the direction of the centrifugal force exerted on the stirring blades 4 of this circle in a supergravity environment.

[0076] Specifically, each circle of stirring blades 4 is connected to the stirring main shaft 5 by a fixing bolt 12, and the extension direction of the plane where each circle of stirring blades 4 is located is equal to the direction of the intersection of the connection point of the stirring blade 4 and the stirring main shaft 5 pointing to the rotation center of the centrifuge (that is, the direction of the centrifugal force exerted on the stirring blade 4). When the stirring blade 4 continues to rotate, at a certain moment, the extension direction of the stirring blade is opposite to the supergravity centrifugal direction exerted on the particles in the mud. The blade at this moment stirs the mud particles, which can better prevent the sedimentation of the particles in the mud.

[0077] The model box 1 is arranged with six vertical grilles 6 and three horizontal grilles 6 on both sides of the long sides, and three horizontal grilles 6 on one of the sides of the short sides. No grille 6 is set on the other side of the short side of the model box 1. The grille 6 is used to improve the strength of the model box 1 to prevent the model box 1 from deformation or damage in a hypergravity environment.

[0078] like Figure 5As shown, the geotechnical centrifuge 10 includes a first hanging basket 101, a second hanging basket 103, a centrifuge base and a control center 11; the first hanging basket 101 and the second hanging basket 103 are fixedly installed on both sides of the centrifuge base through a rotating arm 104, a counterweight block 102 is placed inside the first hanging basket 101, a mud anti-sedimentation device is fixedly installed on the second hanging basket 103, and a cable 105 is provided on the rotating arm 104 connecting the second hanging basket 403 and the centrifuge base, and the photoelectric speed meter 7, the ultrasonic densitometer 8 and the camera 9 are all connected to the control center 11 through the cable 105; the control center 11 is used to obtain the density of the mud, the speed of the stirring motor 3 and the rotation image of the stirring motor 3 during the test.

[0079] A reliability verification method includes a reliability verification method for a monitoring component under hypergravity conditions and a mud anti-sedimentation effect verification method for a stirring component under hypergravity conditions.

[0080] A reliability verification method for monitoring components under hypergravity conditions comprises the following steps:

[0081] Step 1. Check the sealing of the device: Fill the model box 1 with water, use a glass hydrometer to test the density of the water in the model box 1, turn on the stirring motor 3 and continue stirring for 10 minutes. During the stirring process, check the water sealing of each device and interface:

[0082] If the sealing condition of each instrument is good, proceed to step 2;

[0083] Otherwise, reassemble the device until all equipment in the device are well sealed;

[0084] Step 2, obtaining the maximum speed n of the stirring motor 3: starting the stirring motor 3 and setting the speed of the stirring motor 3 to 1 r / min, gradually increasing the speed of the stirring motor 3 in increments of 1 r / min, when the camera 9 cannot identify the stirring motor 3, recording the speed of the stirring motor 3 at this time as n+1 r / min, where n is the maximum speed of the stirring motor 3;

[0085] Step 3, install the entire device in the second hanging basket 103 of the geotechnical centrifuge 10, and ensure the stability of the device installation; after the device is placed stably, under normal gravity conditions, turn on the stirring motor 3 and set the speed of the stirring motor 3 to the maximum speed n;

[0086] Step 4, start the geotechnical centrifuge 10, increase the acceleration of the geotechnical centrifuge 10, and after the acceleration reaches the target Ng value, maintain the Ng value for 30 minutes. During the process of maintaining the stable Ng value, record the ultrasonic densitometer 8 indication, the photoelectric velocimeter 7 indication, and the speed of the stirring motor 3 recognized by the camera 9 every 10 minutes;

[0087] Step 5: Compare the ultrasonic densitometer 8 indication, the photoelectric velocimeter 7 indication and the stirring motor 3 speed recognized by the camera 9 recorded during the test with the density of water under normal gravity and the set speed of the stirring motor 3 to verify the reliability of the monitoring component.

[0088] Step 6: Use a monitoring component that has passed reliability verification to measure the true density of the test liquid and the true speed of the stirring motor 3 under the hypergravity environment.

[0089] Specifically, step 5 is as follows:

[0090] Step 5.1. Compare the reading of the ultrasonic density meter 8 during the test with the density of water under normal gravity to verify the reliability of the ultrasonic density meter 8:

[0091] If the indication on the ultrasonic density meter 8 is the same as the indication on the glass density meter, it indicates that the ultrasonic density meter 8 works normally in the hypergravity environment, the reliability verification is qualified, and the true density of the test liquid is the indication of the ultrasonic density meter 8;

[0092] Otherwise, it indicates that the ultrasonic density meter 8 fails in the hypergravity environment and the reliability verification fails. The ultrasonic density meter 8 is corrected according to the difference between the indication of the ultrasonic density meter 8 and the indication of the glass hydrometer. The true density of the test liquid is the indication of the ultrasonic density meter 8 plus △ρ, △ρ = indication of the glass hydrometer - indication of the ultrasonic density meter 8;

[0093] Step 5.2: Compare the rotation speed of the stirring motor 3 identified by the camera 9 during the test with the set rotation speed n of the stirring motor 3 to verify the reliability of the stirring motor 3:

[0094] If the rotation speed of the stirring motor 3 identified by the camera 9 is within a 5% range from the set maximum rotation speed n, it indicates that the stirring motor 3 works normally in the hypergravity environment, and the reliability verification is qualified, and the process goes to step 5.3;

[0095] Otherwise, it indicates that the stirring motor 3 fails in the hypergravity environment and the reliability verification fails. The stirring motor 3 is replaced and the reliability verification of the stirring motor 3 is performed again in the hypergravity environment until the reliability verification of the stirring motor 3 passes.

[0096] Step 5.3, compare the indication of the photoelectric speed meter 7 during the test with the qualified rotation speed of the stirring motor 3 identified by the camera 9 to verify the reliability of the photoelectric speed meter 7:

[0097] If the value indicated by the photoelectric velocimeter 7 is consistent with the qualified rotation speed of the stirring motor 3 identified by the camera 9, it indicates that the photoelectric velocimeter 7 works normally in the hypergravity environment, the reliability verification is qualified, and the real rotation speed of the stirring motor 3 is the value indicated by the photoelectric velocimeter 7;

[0098] Otherwise, it indicates that the photoelectric speed meter 7 fails in the hypergravity environment and the reliability verification fails. According to the difference between the indication of the photoelectric speed meter 7 and the rotation speed of the stirring motor 3 recognized by the camera 9, the photoelectric speed meter 7 is corrected. The real rotation speed of the stirring motor 3 is the indication of the photoelectric speed meter 7 plus △v, △v = the rotation speed of the stirring motor 3 recognized by the camera 9 - the indication of the photoelectric speed meter 7.

[0099] The reliability verification method of the anti-sedimentation effect of the stirring assembly mud under high gravity conditions includes the following steps:

[0100] Step 1: Prepare Bentonite Slurry

[0101] The bentonite particles, sodium carboxymethyl cellulose CMC and water are mixed in a preset ratio and stirred thoroughly. After stirring, the mixture is allowed to stand for more than 24 hours to obtain a bentonite slurry. When no precipitation is observed in the bentonite slurry, the density of the bentonite slurry is measured using an ultrasonic densitometer 8 as the calibrated density of the slurry.

[0102] Step 2: Check the tightness of the device

[0103] Assemble the whole device under normal gravity, then fill the model box 1 with mud, turn on the stirring motor 3 for 10 minutes, and check the water sealing of each device and interface during the stirring process:

[0104] If the sealing condition of each instrument is good, proceed to step 3;

[0105] Otherwise, reassemble the device until all equipment in the device are well sealed;

[0106] Step 3: Install the entire device in the second hanging basket 103 of the geotechnical centrifuge 10, and ensure the stability of the device installation; after the device is placed stably, under normal gravity conditions, turn on the stirring motor 3 to stir the bentonite slurry in the model box 1 and set the speed of the stirring motor 3 to 40r / min;

[0107] Step 4: Start the geotechnical centrifuge 10, increase the acceleration of the geotechnical centrifuge 10, and maintain the Ng value for 30 minutes after the acceleration reaches the target Ng value; while maintaining the stable Ng value, verify the mud anti-sedimentation effect of the stirring assembly according to the real-time mud density.

[0108] Step 5: Set up the anti-mud settling device using a stirring assembly that has been proven to be reliable.

[0109] In step 4, the mud anti-sedimentation effect of the stirring assembly is verified according to the mud density, and the following steps are specifically adopted: after the centrifugal acceleration Ng value is stable, the density of the mud at different heights is recorded every 10 minutes and compared with the mud calibration density under normal gravity, etc.:

[0110] If the difference between the ultrasonic density meter 8 reading at the same height and the calibrated density of the mud under normal gravity is within the preset range, it indicates that the mud anti-sedimentation effect of the stirring assembly is qualified at the current rotation speed;

[0111] Otherwise, it indicates that the mud anti-sedimentation effect of the stirring assembly is unqualified at the current rotation speed. The stirring assembly should be replaced or the rotation speed of the stirring motor 3 should be increased until the mud anti-sedimentation effect of the stirring assembly is qualified.

[0112] In step 4, the allowable range of the mud density measured by the ultrasonic density meter 8 under supergravity conditions also includes the following limiting conditions: under supergravity conditions, the difference between the mud density measured by the ultrasonic density meter 8 at the bottom / top of the model box 1 and the mud density measured by the ultrasonic density meter in the middle is not greater than 0.0025 g / m 3 .

[0113] Personnel in the technical field can easily make various changes and modifications based on the text description, drawings and claims provided by the present invention without departing from the concept and scope of the present invention defined by the claims. Any modification or equivalent change made to the above embodiments based on the technical concept and essence of the present invention shall fall within the scope of protection defined by the claims of the present invention.

Claims

1. A mud anti-sedimentation device under super gravity conditions, characterized in that: The invention comprises a model box (1), a sealing partition (2), two groups of stirring components and a monitoring component; the model box (1) is an internal hollow structure with an open top and a closed bottom; the model box (1) is used to store mud; the sealing partition (2) is connected to the top of the model box (1); one end of the stirring component extends into the mud stored in the model box (1) and is used to stir the mud; the monitoring component is arranged inside the model box and is used to monitor the sedimentation of the mud and the working condition of the stirring component in real time during the test; the mud anti-sedimentation device is placed on a geotechnical centrifuge (10), and the device is electrically connected to a control center (11) in the geotechnical centrifuge (10); The two groups of stirring components are arranged at intervals along the height direction of the model box (1), and the two groups of stirring components are arranged horizontally along the long side direction of the model box (1). Each group of stirring components comprises a stirring motor (3) and a plurality of stirring blades (4). Two stirring through holes are provided on the side wall of the model box (1). The housing of the stirring motor (3) is fixedly connected to the side wall of the model box (1). The stirring main shaft (5) of the stirring motor (3) passes through the stirring through holes on the side wall of the model box (1) and extends into the mud. The plurality of stirring blades (4) are connected to the stirring main shaft (5) at intervals along the axial direction of the stirring main shaft (5). The monitoring assembly comprises a photoelectric velocimeter (7), three ultrasonic densitometers (8) and two cameras (9); the photoelectric velocimeter (7) is connected to the lower surface of the sealing partition (2) and is used to monitor the rotation speed of the stirring motor (3) in real time; three monitoring holes at different heights are opened on the outer wall of the model box (1), and the probes of the three ultrasonic densitometers (8) are respectively inserted through the three monitoring holes and extend into the mud, and the ultrasonic densitometers (8) are used to record the density of the mud at different heights in the model box (1) in real time; two cameras (9) are respectively installed on the stirring spindles (5) of the two stirring motors (3), and the cameras (9) are used to verify the reliability of the photoelectric velocimeter (7) under supergravity conditions; Each circle of stirring blades (4) is mainly formed by a plurality of stirring blades (4) arranged evenly and spaced apart along the circumference of the stirring main shaft (5); the stirring blades (4) of the same circle are located on the same plane; and the extension direction of the plane where the stirring blades (4) of each circle are located is the direction of the centrifugal force to which the stirring blades (4) of this circle are subjected in a supergravity environment.

2. The device for preventing mud from settling under high gravity conditions according to claim 1, characterized in that: The model box (1) is provided with six vertical grilles (6) and three horizontal grilles (6) on both sides of the long sides, and three horizontal grilles (6) on one side of the short sides of the model box (1). No grilles (6) are provided on the other side of the short side of the model box (1). The grilles (6) are used to improve the strength of the model box (1) and prevent the model box (1) from being deformed or damaged in a hypergravity environment.

3. The device for preventing mud from settling under high gravity conditions according to claim 1, characterized in that: The geotechnical centrifuge (10) comprises a first hanging basket (101), a second hanging basket (103), a centrifuge base and a control center (11); the first hanging basket (101) and the second hanging basket (103) are respectively fixedly mounted on both sides of the centrifuge base via a rotating arm (104); a counterweight (102) is placed inside the first hanging basket (101); a mud anti-sedimentation device is fixedly mounted on the second hanging basket (103); a cable (105) is arranged on the rotating arm (104) connecting the second hanging basket (103) and the centrifuge base; a photoelectric velocimeter (7), an ultrasonic densitometer (8) and a camera (9) are all connected to the control center (11) via the cable (105); the control center (11) is used to obtain the density of the mud, the speed of the stirring motor (3) and the rotation image of the stirring motor (3) during the test.

4. A reliability verification method for monitoring components under hypergravity conditions applied to the device of claim 3, characterized in that: The following steps are involved: Step 1. Check the tightness of the device: Fill the model box (1) with water, use a glass hydrometer to test the density of the water in the model box (1), turn on the stirring motor (3) and continue stirring for 10 minutes. During the stirring process, check the water tightness of each device and interface: If the sealing condition of each instrument is good, proceed to step 2; Otherwise, reassemble the device until all equipment in the device are well sealed; Step 2, obtaining the maximum speed n of the stirring motor (3): starting the stirring motor (3) and setting the speed of the stirring motor (3) to 1 r / min, gradually increasing the speed of the stirring motor (3) in increments of 1 r / min, and when the camera (9) cannot recognize the stirring motor (3), recording the speed of the stirring motor (3) at this time as n+1 r / min, wherein n is the maximum speed of the stirring motor (3); Step 3, installing the entire device in the second hanging basket (103) of the geotechnical centrifuge (10), and ensuring the stability of the device installation; after the device is placed stably, under normal gravity conditions, start the stirring motor (3) and set the speed of the stirring motor (3) to the maximum speed n; Step 4, starting the geotechnical centrifuge (10), increasing the acceleration of the geotechnical centrifuge (10), and maintaining the Ng value for 30 minutes after the acceleration reaches the target Ng value. During the process of maintaining the stable Ng value, the indication of the ultrasonic densitometer (8), the indication of the photoelectric velocimeter (7), and the rotation speed of the stirring motor (3) recognized by the camera (9) are recorded every 10 minutes; Step 5: compare the ultrasonic density meter (8), the photoelectric velocimeter (7) and the rotation speed of the stirring motor (3) recorded during the test with the density of water under normal gravity and the set rotation speed of the stirring motor (3) to verify the reliability of the monitoring component.

5. The reliability verification method of a monitoring component under hypergravity conditions according to claim 4 is characterized in that: The step 5 is specifically as follows: Step 5.1: Compare the reading of the ultrasonic density meter (8) during the test with the density of water under normal gravity to verify the reliability of the ultrasonic density meter (8): If the indication on the ultrasonic density meter (8) is the same as the indication on the glass density meter, it indicates that the ultrasonic density meter (8) works normally in the hypergravity environment and the reliability verification is qualified; Otherwise, it indicates that the ultrasonic density meter (8) fails in the hypergravity environment and the reliability verification fails. The ultrasonic density meter (8) is corrected according to the difference between the indication of the ultrasonic density meter (8) and the indication of the glass hydrometer; Step 5.2: Compare the rotation speed of the stirring motor (3) identified by the camera (9) during the test with the set rotation speed n of the stirring motor (3) to verify the reliability of the stirring motor (3): If the rotation speed of the stirring motor (3) identified by the camera (9) has an error within 5% of the set maximum rotation speed n, it indicates that the stirring motor (3) works normally in the hypergravity environment, the reliability verification is qualified, and the process proceeds to step 5.3; Otherwise, it indicates that the stirring motor (3) fails in the hypergravity environment and the reliability verification fails. The stirring motor (3) is replaced and the reliability verification of the stirring motor (3) is performed again in the hypergravity environment until the reliability verification of the stirring motor (3) passes. Step 5.3: Compare the reading of the photoelectric velocimeter (7) during the test with the qualified rotation speed of the stirring motor (3) identified by the camera (9) to verify the reliability of the photoelectric velocimeter (7): If the value indicated by the photoelectric speed meter (7) is consistent with the qualified rotation speed of the stirring motor (3) identified by the camera (9), it indicates that the photoelectric speed meter (7) works normally in the hypergravity environment and the reliability verification is qualified; Otherwise, it indicates that the photoelectric speed meter (7) fails in the hypergravity environment and the reliability verification fails. The photoelectric speed meter (7) is corrected according to the difference between the indication of the photoelectric speed meter (7) and the rotation speed of the stirring motor (3) identified by the camera (9).

6. A reliability verification method for the anti-sedimentation effect of the mud of the stirring assembly under supergravity conditions applied to the device of claim 3, characterized in that: The following steps are involved: Step 1: Prepare bentonite slurry Mixing bentonite particles, sodium carboxymethyl cellulose (CMC) and water in a preset ratio and stirring them thoroughly, leaving the mixture to stand for more than 24 hours after stirring to obtain bentonite slurry, and measuring the density of the bentonite slurry using an ultrasonic densitometer (8) when no precipitation is observed in the bentonite slurry as the calibrated density of the slurry; Step 2: Check the sealing of the device Assemble the entire device under normal gravity conditions, then fill the model box (1) with mud, turn on the stirring motor (3) for 10 minutes, and check the water sealing conditions of each device and interface during the stirring process: If the sealing condition of each instrument is good, proceed to step 3; Otherwise, reassemble the device until all equipment in the device are well sealed; Step 3, installing the entire device in the second hanging basket (103) of the geotechnical centrifuge (10), and ensuring the stability of the device installation; after the device is placed stably, under normal gravity conditions, start the stirring motor (3) to stir the bentonite slurry in the model box (1) and set the rotation speed of the stirring motor (3) to 40r / min; Step 4: Start the geotechnical centrifuge (10), increase the acceleration of the geotechnical centrifuge (10), and after the acceleration reaches the target Ng value, maintain the Ng value for 30 minutes; while maintaining the stable Ng value, verify the mud anti-sedimentation effect of the stirring assembly according to the real-time mud density.

7. The reliability verification method of the anti-sedimentation effect of the stirring assembly mud under high gravity conditions according to claim 6 is characterized by: In step 4, the mud anti-sedimentation effect of the stirring assembly is verified according to the mud density, and the following steps are adopted: after the centrifugal acceleration Ng value is stable, the density of the mud at different heights is recorded every 10 minutes and compared with the mud calibration density under normal gravity, etc.: If the difference between the ultrasonic density meter (8) indication and the calibrated density of the mud under normal gravity is within a preset range, it indicates that the mud anti-sedimentation effect of the stirring assembly is qualified at the current rotation speed; Otherwise, it indicates that the mud anti-sedimentation effect of the stirring assembly is unsatisfactory at the current rotation speed, and the stirring assembly is replaced or the rotation speed of the stirring motor (3) is increased until the mud anti-sedimentation effect of the stirring assembly is qualified.

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