CN113385309B - Liquid discharge control device and method for supergravity centrifugal model - Google Patents
Liquid discharge control device and method for supergravity centrifugal model Download PDFInfo
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B04—CENTRIFUGAL APPARATUS OR MACHINES FOR CARRYING-OUT PHYSICAL OR CHEMICAL PROCESSES
- B04B—CENTRIFUGES
- B04B1/00—Centrifuges with rotary bowls provided with solid jackets for separating predominantly liquid mixtures with or without solid particles
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B04—CENTRIFUGAL APPARATUS OR MACHINES FOR CARRYING-OUT PHYSICAL OR CHEMICAL PROCESSES
- B04B—CENTRIFUGES
- B04B11/00—Feeding, charging, or discharging bowls
- B04B11/02—Continuous feeding or discharging; Control arrangements therefor
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- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
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Abstract
The invention discloses a liquid discharge control device and method for a supergravity centrifugal model. The centrifugal liquid discharge control system is composed of a centrifugal model of a hypergravity cabin, a closed liquid storage tank, a centrifuge liquid ring device and a normal gravity vacuum adjusting system, liquid quality or vacuum degree control parameters of the closed liquid storage tank are obtained, and then the vacuum adjusting system adjusts vacuum pressure in real time to meet requirements of the closed liquid storage tank, so that the purpose of meeting discharge control standards of different model test requirements with high precision is achieved. The method intervenes in the hypergravity model liquid discharge control test in real time by forming a hypergravity-constant gravity dual-environment cooperation platform, achieves the result of high-precision and high-efficiency control on the liquid discharge in the model, is simple, convenient and feasible, is suitable for other batches of tests, and is scientific and easy to popularize.
Description
Technical Field
The invention belongs to a device and a method for controlling under hypergravity in the field of a hypergravity centrifugal model test, and particularly relates to a device and a method for controlling liquid discharge in a hypergravity centrifugal model test.
Background
The hypergravity centrifuge experiment is a scientific research means newly developed in the field of geotechnical engineering in the new century, reduces the structure scale and the acceleration time process by reducing the on-site stress condition of the engineering, and has important characteristics of a soil body internal seepage process and the like to form an extremely effective research tool, and plays a unique role in the national major development planning project. However, because the operating environment of the centrifuge is peculiar, i.e., closed, it is often impossible to accurately and effectively intervene and control variables of the operating conditions of the physical model in the cabin, and therefore, an important problem to be solved is how to achieve the purpose of accurately controlling the physical model under the hypergravity by separating from the centrifuge in an external open environment through a scientific system design.
A typical important scientific problem of the geotechnical engineering hypergravity centrifugal test is the discharge control problem of model liquid in a tank, if the discharge control system and a model are packaged in a hypergravity environment test chamber together, several problems can be faced, one is how to ensure the stable operation of the control system in the hypergravity environment, the other is how to accurately intervene and change seepage conditions through the control system to meet the experimental requirements, the third is to ensure that the attached control equipment cannot cause irreversible disturbance or even damage to the model when in operation, the problems are solved depending on that a controller operating in the normal gravity environment can stably operate in the hypergravity chamber, and in addition, external control personnel can change the seepage working condition of the liquid in the model in real time to meet the experimental requirements and can give feedback in time and the like. Obviously, such a requirement will increase the performance requirements for the model box and the controller, inevitably further complicate the test, increase the failure rate in addition to increasing the difficulty of the test, and influence the precision of the test due to the introduced uncontrollable variables.
Therefore, through scientific system design, the requirement is provided through the design or function of the hypergravity test, intelligent feedback adjustment is directly carried out on the discharge of liquid in the model under the normal gravity environment, and a dual-environment cooperative working platform is formed, so that the system has obvious practical significance for promoting the development of the hypergravity test with high efficiency and high precision.
In the publication of "scientific research on Water conservancy and Water transportation" in journal of 2000, 04 "a new method for simulating foundation pit excavation by centrifugal model test" a discharge device is arranged in a separated space in a model box under the condition of supergravity, and the purpose of discharging liquid in a soil model is achieved by opening and closing an electromagnetic valve in a grading way.
In 'deep foundation pit excavation centrifugal simulation test method with multiple supports' in the journal 2010, volume 06, 2010, of underground space and engineering journal, a liquid discharge system attached to a model and arranged during a centrifugal machine test is introduced, and a speed regulating valve is controlled in a time-sharing manner according to the experiment requirement to change the liquid capacity of the model.
The main disadvantages of the prior art related art or method are as follows:
(1) the liquid discharge problem under the environment of current hypergravity reaches the purpose of drainage, water storage through the device that the inside independent setting of mold box basically, and this must require attached device steady operation under the environment of hypergravity, especially the operation of governing valve and motor, because the big transition of operational environment leads to experimental success or not to be full of the variable.
(2) The existing control device and a model box are integrally packaged together and are arranged in a supergravity cabin, liquid discharge work is carried out passively through conditions such as a preset threshold value and the like basically, the liquid discharge work process depends on the autonomous operation of a control system, the subjective activity of a tester cannot effectively guide the whole test process, feedback cannot be given in time, real-time intervention and control variable adjustment cannot be carried out according to requirements, the whole process is strong in mechanical property, low in precision, low in efficiency and high in failure rate.
(3) The existing liquid discharge system is obtained by modifying a model box, which increases the difficulty of model making, and the highly-personalized liquid control system prevents the function from being transplanted to a different test, so that the universality is low.
The high precision and high flexibility of the hypergravity centrifugal liquid discharge test require that a discharge system capable of being accurately and intelligently controlled is lacked in the prior art, and the control method can be simply, conveniently and easily applied to geotechnical engineering tests of other batches.
Disclosure of Invention
The invention aims to solve the technical problems in the background art and provides a liquid discharge control method and application for a supergravity centrifugal test.
The invention intervenes in the hypergravity model liquid discharge control test in real time by forming a hypergravity-constant gravity dual-environment cooperation platform, and realizes the result of high-precision and high-efficiency control on the liquid discharge in the model.
The technical scheme adopted by the invention is as follows:
a hypergravity centrifugal model liquid discharge control device:
the hypergravity centrifugal machine comprises a hypergravity centrifugal machine main body and a test end hanging basket, wherein a centrifugal model is placed in the test end hanging basket; comprises a liquid region to be drained, a pressure gauge, a closed liquid storage tank, a precision electronic scale, a liquid ring device, a proportion regulating valve and a vacuum regulating system; a liquid body area to be drained is placed in the centrifugal model, a precise electronic scale and a closed liquid storage tank are placed in a test end hanging basket, the closed liquid storage tank is placed on the precise electronic scale, and a liquid ring device is installed at the bottom of a supergravity centrifuge main body; the area of the liquid to be discharged is communicated with a closed liquid storage tank through a liquid pipe in the test end hanging basket, the closed liquid storage tank is connected with a liquid ring device through a gas pipe, and is connected to one end of a proportional control valve through the liquid ring device, the other end of the proportional control valve is connected with a vacuum adjusting system, and a pressure gauge is installed in the vacuum adjusting system.
The air pipe extends out of the test end hanging basket, passes through a rotating arm and a rotating shaft of the supergravity centrifugal machine and is connected to the liquid ring device.
The area of the liquid to be drained is placed in the centrifugal model by adopting a container, and liquid is contained in the container.
The upper end of the area of the liquid to be discharged is provided with a port as a liquid outlet, and the port is communicated with the closed liquid storage tank through a liquid pipe.
The proportion regulating valve and the vacuum regulating system are arranged in a normal gravity environment.
The air vent of the closed liquid storage tank is connected to one port of the liquid ring device through an air pipe, and then is connected to the vacuum regulation system in the normal gravity environment through another section of pipeline through the other port of the liquid ring device.
Secondly, a liquid discharge control method of a supergravity centrifugal model comprises the following steps:
s1, establishing a liquid quality control parameter Z of the closed liquid storage tank1And vacuum requirement control parameter Z2；
S2, before the super-gravity centrifuge works, the liquid quality control parameter Z of the closed liquid storage tank meeting the requirement of S1 is enabled to be met through adjusting the vacuum adjusting system of the normal gravity environment in real time1And vacuum requirement control parameter Z2；
S3, under the working condition of the hypergravity centrifuge, monitoring the state change of the centrifuge model under the hypergravity environment in real time according to the vacuum adjusting system, and controlling the parameter Z according to the liquid quality of the sealed liquid storage tank of S11And vacuum requirement control parameter Z2And (5) judging and checking the test until the test is satisfied.
And in S1, controlling the liquid quality Z of the sealed liquid storage tank1And vacuum degree control parameter Z2The method specifically comprises the following steps:
liquid quality control parameter Z1Expressed as the following relationship:
Z1＝ΔM/Δt
wherein Z is1The method comprises the steps of representing a liquid quality control parameter of a closed liquid storage tank, wherein delta M is the variable quantity of the liquid quality in the closed liquid storage tank within a preset time interval delta t;
vacuum degree control parameter Z2Expressed as the following relationship:
Z2＝ΔP
wherein Z is2And the delta P is the vacuum pressure difference of the vacuum regulating system in the normal gravity environment.
The S2 specifically includes:
s2.1, controlling the parameter Z according to the preset liquid quality1And the upper and lower limit error of liquid mass Delta Z1Establishing a liquid quality control range Z1-ΔZ1～Z1+ΔZ1；
S2.2, performing vacuum pumping work by a vacuum regulating system according to preset pumping flow, and meanwhile, controlling the opening of a proportional regulating valve to pre-regulate the vacuum difference in the closed liquid storage tank;
the method is characterized in that manual adjustment is used for adjusting to an empirical value in advance, then the system enters an automatic adjustment link, and since real-time closed-loop feedback automatic adjustment is needed to be achieved finally, the manual adjustment is performed in advance to reach a relatively close empirical value, so that the automatic adjustment link can achieve dynamic balance in a short time.
S2.3, detecting the mass change quantity delta M of the liquid in the closed liquid storage tank in real time through a precise electronic scale at the bottom of the closed liquid storage tank, and calculating the liquid discharge rate delta M/delta t of the liquid in the closed liquid storage tank according to the real-time mass change quantity delta M of the liquid;
s2.4, according to the liquid discharge rate delta M/delta t obtained in real time and the set liquid quality control parameter Z1The control feedback of the vacuum regulating system regulates the pumping flow of the vacuum regulating system and the opening of the proportional regulating valve in real time, so that the liquid discharge rate delta M/delta t is in the liquid quality control range Z1-ΔZ1～Z1+ΔZ1And (4) the following steps.
The S3 specifically includes:
s3.1, controlling a parameter Z according to preset vacuum degree2And vacuum degree control upper and lower limit error delta Z2Establishing a vacuum control range Z2-ΔZ2～Z2+ΔZ2；
S3.2, performing vacuum pumping work by a vacuum regulating system according to preset pumping flow, and meanwhile, controlling the opening of a proportional regulating valve to pre-regulate the vacuum difference in the closed liquid storage tank;
s3.3, feeding back the vacuum pressure of the vacuum regulation system in real time through a pressure gauge on the top of the sealed liquid storage tank to obtain a vacuum pressure fluctuation change value delta P/delta t in unit time;
s3.4, obtaining the change value delta P/delta t of vacuum pressure fluctuation and the set vacuum degree control parameter Z in real time2Comparing feedback, and adjusting the pumping flow of the vacuum adjusting system and the opening of the proportional adjusting valve in real time to ensure that the vacuum pressure fluctuation variation value delta P/delta t is within the vacuum degree control range Z2-ΔZ2～Z2+ΔZ2And (4) the following steps.
The method of the invention is characterized in that a centrifugal liquid discharge control system consisting of a centrifugal model of the hypergravity cabin, a closed liquid storage tank, a centrifugal machine liquid ring device and a normal gravity vacuum adjusting system is used for providing model liquid discharge control parameters according to test requirements to obtain quality or vacuum degree control parameters of the liquid storage tank, and then the vacuum adjusting system adjusts vacuum pressure in real time to meet the requirements of the closed liquid storage tank, thereby realizing the purpose of meeting the discharge control standards of different model test requirements with high precision.
As shown in fig. 2, the present invention includes portions of the structure that are placed under high gravitational forces, as well as portions of the structure that are placed under normal gravitational forces.
According to the device and the method, all the control devices and the control sources work in the normal gravity environment, and the model in the hypergravity environment can be intervened through the control devices in the normal gravity environment, so that the hypergravity environment is accurately and effectively controlled outside the hypergravity environment. The problem of in prior art all set up in hypergravity environment and bring to liquid discharge control under the hypergravity environment all in the hypergravity environment is solved, the problem that liquid discharge control is exerted equipment and action and is brought the interference inside the hypergravity environment has been solved, the problem that the utilization is exerted equipment and action and can bring more interference for the experimental model inside the hypergravity environment has also been solved.
The invention has the beneficial effects that:
the invention further changes the vacuum degree of the sealed liquid storage tank of the hypergravity cabin by the liquid ring device of the centrifugal machine through the vacuum adjusting system in the normal gravity environment, thereby achieving the purpose of carrying out high-precision control on the liquid discharge test in the model.
Firstly, the method greatly reduces the strong dependence of the model test on the accessory equipment, fundamentally simplifies the complexity of the test, reduces the interference of the model, and also reduces the high-performance requirement on the equipment, so that the test carried out by the method is safer compared with the prior related technology;
then, accurate intervention on the physical and mechanical states of the model in the hypergravity environment is realized through the constant gravity control system, the two environments are in dependent cooperative work, the test efficiency is improved, new requirements and new parameters can be provided according to the requirements of the model test in real time, the feedback and the change are carried out in time, and the scientificity is stronger;
then, the model and the liquid discharge control system are separated, so that the system can be conveniently suitable for other types of supergravity tests, and can be conveniently moved regardless of static water pumping or dynamic water discharge tests, and the wider universality is not solved by the prior art;
finally, the precision is higher, including high accuracy quality control and high accuracy vacuum degree adjusting device, easy and simple to handle, and the analysis cost is practiced thrift to scientific system design when guaranteeing hypergravity centrifugal test steady operation, easily uses widely.
The method can meet the requirements of high precision and high flexibility of the ultragravity centrifugal liquid discharge test, and the control method can be simple, convenient and feasible, is suitable for other batch tests, and is high in scientificity and easy to popularize.
Drawings
FIG. 1 is a schematic diagram of the composition of a supergravity centrifugal liquid discharge control test system;
FIG. 2 is a schematic diagram of a liquid discharge control system;
FIG. 3 is a schematic diagram of a hypergravity foundation pit centrifugal model according to an embodiment of the invention;
FIG. 4 is a flow chart of a test of a method of supergravity centrifugal liquid discharge control;
fig. 5 is a schematic diagram of a liquid discharge control test condition of a certain foundation pit centrifugal model.
In the figure: the device comprises a test end hanging basket 1, a centrifugal model 2, a liquid to be discharged area 3, a pressure gauge 4, a closed liquid storage tank 5, a precision electronic scale 6, a hypergravity centrifuge body 7, a liquid ring device 8, a proportion adjusting valve 9 and a vacuum adjusting system 10.
Detailed Description
The invention is further described with reference to the following figures and specific embodiments.
As shown in fig. 1, the hypergravity centrifuge comprises a hypergravity centrifuge main body 7 and a test end hanging basket 1, wherein a centrifugal model 2 is placed in the test end hanging basket 1, and the bottom of the centrifugal model 2 is fixed on the inner bottom surface of the test end hanging basket 1; the device also comprises a liquid area to be drained 3, a pressure gauge 4, a closed liquid storage tank 5, a precision electronic scale 6, a liquid ring device 8, a proportion regulating valve 9 and a vacuum regulating system 10; the proportional control valve 9 and the vacuum regulating system 10 are placed in a normal gravity environment, and the rest of the devices are placed in a supergravity environment.
A region 3 to be drained is placed in a centrifugal model 2, a precise electronic scale 6 and a sealed liquid storage tank 5 are placed in a test end hanging basket 1, the sealed liquid storage tank 5 is placed beside the centrifugal model 2, the sealed liquid storage tank 5 is placed on the precise electronic scale 6, and a liquid ring device 8 is installed at the bottom of a supergravity centrifuge main body 7; the liquid to be discharged area 3 is communicated with a closed liquid storage tank 5 through a liquid pipe in the test end hanging basket 1, the closed liquid storage tank 5 is connected with a liquid ring device 8 through an air pipe, and is connected to one end of a proportional control valve 9 through the liquid ring device 8, the other end of the proportional control valve 9 is connected with a vacuum adjusting system 10, namely, the liquid ring device 8 is connected with the vacuum adjusting system 10 through the proportional control valve 9, and a pressure gauge 4 is installed in the vacuum adjusting system 10.
The precise electronic scale 6 is used for detecting the pressure applied to the precise electronic scale 6 by the closed liquid storage tank 5 under the condition of supergravity, and the pressure gauge 4 is used for detecting the vacuum degree in the vacuum adjusting system 10 under the condition of supergravity.
The air pipe extends out of the test end hanging basket 1, passes through a rotating arm and a rotating shaft of the hypergravity centrifugal machine and is connected to the liquid ring device 8.
The area 3 to be drained is placed in the centrifugal model 2 by adopting a container, the container is fixed in the model soil body in the centrifugal model 2, and the liquid is contained in the container. The upper end of the area 3 to be liquid-drained is provided with a port as a liquid outlet, the port is communicated with the closed liquid storage tank 5 through a liquid pipe, and the liquid pipe is connected with the liquid outlet of the area 3 to be liquid-drained in the centrifugal model 2 and a liquid through port of the closed liquid storage tank 5. The vent of the closed liquid storage tank 5 is connected to one port of the liquid ring device 8 through a gas pipe, and is connected to the vacuum regulation system in the normal gravity environment through another section of pipeline through the other port of the liquid ring device 8.
The vacuum regulating system 10 has a vacuum pump therein, and the vacuum pumping operation is performed by the vacuum pump. When the vacuum adjusting system 10 works, the opening degree is adjusted through the proportion adjusting valve 9, the gas in the closed liquid storage tank 5 is pumped into the vacuum adjusting system 10, and the gas in the closed liquid storage tank 5 is pumped, so that the air pressure is reduced, and the liquid in the liquid area to be discharged 3 is further driven to be pumped into the closed liquid storage tank 5 through the liquid pipe, and the basic function of liquid discharge is realized.
The implementation process of the invention specifically comprises the following steps:
s1, establishing a liquid quality control parameter Z of the closed liquid storage tank 51And vacuum requirement control parameter Z2(ii) a The method specifically comprises the following steps:
liquid quality control parameter Z1Expressed as the following relationship:
Z1＝ΔM/Δt
wherein Z is1The control parameter of the liquid quality of the closed liquid storage tank 5 is shown, wherein delta M is the variation of the liquid quality in the closed liquid storage tank 5 which needs to be controlled within a preset time interval delta t, and delta M/delta t is the liquid discharge control rate;
vacuum degree control parameter Z2Expressed as the following relationship:
Z2＝ΔP
wherein Z is2And the control parameter of the vacuum degree of the closed liquid storage tank 5 is shown, and delta P is the vacuum pressure difference of the vacuum regulating system 10 in the normal gravity environment.
S2, before the super-gravity centrifuge works, the liquid quality control parameter Z of the closed liquid storage tank 5 meeting the requirement of S1 is enabled to be met through adjusting the vacuum adjusting system 10 in the normal gravity environment in real time1And vacuum requirement control parameter Z2；
S2.1, controlling the parameter Z according to the preset liquid quality1And the upper and lower limit error of liquid mass Delta Z1Establishing a liquid quality control range Z1-ΔZ1～Z1+ΔZ1；
S2.2, performing vacuum pumping work by the vacuum regulating system 10 according to preset pumping flow, and meanwhile, controlling the opening of the proportion regulating valve 9 to regulate the vacuum difference in the closed liquid storage tank 5 in advance;
the method is characterized in that manual adjustment is used for adjusting to an empirical value in advance, then the system enters an automatic adjustment link, and since real-time closed-loop feedback automatic adjustment is needed to be achieved finally, the manual adjustment is performed in advance to reach a relatively close empirical value, so that the automatic adjustment link can achieve dynamic balance in a short time.
S2.3, detecting the mass change quantity delta M of the liquid in the closed liquid storage tank 5 in real time through a precise electronic scale 6 at the bottom of the closed liquid storage tank 5, and calculating the liquid discharge rate delta M/delta t of the liquid in the closed liquid storage tank 5 according to the real-time mass change quantity delta M of the liquid;
s2.4, according to the drainage rate delta M/delta t obtained in real time and the set liquid quality control parameter Z1The control feedback of the vacuum regulating system 10, the pumping flow of the vacuum regulating system and the opening of the proportional regulating valve 9 are comprehensively regulated in real time, so that the liquid discharge rate delta M/delta t is in the liquid quality control range Z1-ΔZ1～Z1+ΔZ1And (4) the following steps.
Specifically, the liquid discharge rate Δ M × Δ t may be compared with the set liquid quality control parameter Z1The difference between the two is input into a PID controller for feedback closed loop regulation.
If the difference is positive, the evacuation flow rate of the vacuum regulation system 10 decreases and/or the opening degree of the proportional control valve 9 decreases. If the difference is negative, the evacuation flow rate of the vacuum regulation system 10 increases and/or the opening degree of the proportional control valve 9 increases.
S3, under the working condition of the supergravity centrifugal machine, monitoring the state change of the centrifugal model 2 in the supergravity environment in real time according to the vacuum degree change quantity of the vacuum adjusting system 10, and controlling the parameter Z according to the liquid quality of the closed liquid storage tank 5 of S11And vacuum requirement control parameter Z2And (5) judging and checking the test until the test is satisfied.
In the concrete implementation, the liquid quality control parameter Z is provided according to the state change condition of the centrifugal model 2 monitored in real time1And vacuum requirement control parameter Z2And repeating the whole process until all test requirements are met, and finishing the centrifugal model test.
S3.1, controlling a parameter Z according to preset vacuum degree2And vacuum degree control upper and lower limit error delta Z2Establishing a vacuum control range Z2-ΔZ2～Z2+ΔZ2；
S3.2, performing vacuum pumping work by the vacuum regulating system 10 according to preset pumping flow, and meanwhile, controlling the opening of the proportion regulating valve 9 to regulate the vacuum difference in the closed liquid storage tank 5 in advance;
the system is adjusted to an empirical value in advance by manual adjustment, and then enters an automatic adjustment link of the system, so that the prior manual adjustment reaches a relatively close empirical value, the automatic adjustment link can achieve dynamic balance in a short time, and real-time closed-loop feedback automatic adjustment can be better realized.
S3.3, feeding back the vacuum pressure of the vacuum adjusting system 10 in real time through a pressure gauge 4 at the top of the closed liquid storage tank 5 to obtain a vacuum pressure fluctuation change value delta P/delta t in unit time;
s3.4, obtaining the change value delta P/delta t of vacuum pressure fluctuation and the set vacuum degree control parameter Z in real time2Comparing feedback, and comprehensively adjusting the pumping flow of the vacuum adjusting system 10 and the opening of the proportional adjusting valve 9 in real time to ensure that the vacuum pressure fluctuation variation value delta P/delta t is in the vacuum degree control range Z2-ΔZ2～Z2+ΔZ2And (4) inside.
Specifically, the vacuum pressure fluctuation variation value Δ P × Δ t and the set vacuum degree control parameter Z may be set2The difference between the two is input into a PID controller for feedback closed loop regulation.
If the difference is positive, the evacuation flow rate of the vacuum regulation system 10 decreases and/or the opening degree of the proportional control valve 9 decreases. If the difference is negative, the evacuation flow rate of the vacuum regulation system 10 increases and/or the opening degree of the proportional control valve 9 increases.
The adjustment of the air-extraction flow rate of the integrated vacuum adjustment system 10 and the opening degree of the proportional adjustment valve 9 is performed by coarse adjustment through the vacuum adjustment system 10 and fine adjustment through the proportional adjustment valve 9.
The method of the invention is implemented by taking a simulation test of excavation of a foundation pit of a certain hypergravity centrifugal model as an example, the design of the model test is shown in figure 3, and the specific implementation process is explained as follows:
first, a model box to be tested is arranged in a basket at the test end of the centrifuge of the hypergravity tank according to the test protocol, as shown in fig. 3.
The centrifugal model comprises a model box, a model soil body is placed in the model box, a container is fixed in the model soil body through a model anchor rod, liquid to be discharged is filled in the container to serve as a model foundation pit, a sensor is arranged on the side wall of the container,
and a soil pressure sensor and a pore water pressure sensor are arranged on the side wall of the container, and the sensors are utilized to measure the acting force change condition of the soil body to the foundation pit in the drainage process of the foundation pit.
Then, the test is started according to the liquid discharge control test flow shown in fig. 4, the model liquid discharge control parameter Y is provided according to the centrifugal model test requirement, and the liquid discharge control parameter Y is provided according to the foundation pit excavation simulation test1Total water level H of the liquid area to be drained.
Simulating three excavation stages according to experimental design, presetting a water level reduction rate parameter controlled in a given time interval and corresponding upper and lower error control limits of each excavation stage, and correspondingly obtaining liquid quality control parameters Z of the three excavation stages1And vacuum requirement control parameter Z2And the matched upper and lower limit errors.
And then, starting from the first excavation stage, enabling the water level reduction rate of fluctuation change or the monitored liquid quality change rate of the closed liquid storage tank to be always in a controlled range by adjusting the vacuum adjusting system of the normal gravity environment in real time, monitoring the physical and mechanical state change of the model in the hypergravity environment in real time to judge whether the preset model liquid discharge control parameters are proper or not, and stopping discharging the liquid for a period of time when the first excavation stage is finished to determine whether the parameters or the upper and lower error limits are changed in real time or not.
And then, carrying out excavation experiments of a second stage, and adjusting the vacuum adjusting system in real time again to enable the fluctuation rate to be always in a new reference value and the corresponding upper and lower limit ranges, and when the second excavation stage is finished, stopping discharging liquid for a period of time to determine whether to change the controlled parameters or the error upper and lower limits in real time.
And then, carrying out excavation experiments at the third stage, and adjusting the vacuum adjusting system in real time again to enable the parameters of fluctuation to be always in a new reference value and the corresponding upper and lower limit ranges.
And finally, when the third excavation stage is finished, a set test scheme is finished, whether the test requirement is met or not can be judged, if so, the control parameters can be changed in real time for subsequent tests, and if the test requirement is met, the whole centrifugal test is finished.
The final test result is shown in fig. 5, different model liquid discharge control parameters exist at different test stages, namely different closed liquid storage tank liquid quality control parameters exist, and the fluctuating controlled parameters are always located within the upper and lower limit ranges of given precision through a vacuum adjusting system, so that real-time change, real-time monitoring, real-time feedback and high-precision control are realized.
Claims (9)
1. A supergravity centrifugal model liquid discharge control device comprises a supergravity centrifugal machine main body (7) and a test end hanging basket (1), wherein a centrifugal model (2) is placed in the test end hanging basket (1); the method is characterized in that: comprises a liquid region (3) to be drained, a pressure gauge (4), a closed liquid storage tank (5), a precise electronic scale (6), a liquid ring device (8), a proportion regulating valve (9) and a vacuum regulating system (10); a liquid area (3) to be drained is placed in the centrifugal model (2), a precise electronic scale (6) and a closed liquid storage tank (5) are placed in the test end hanging basket (1), the closed liquid storage tank (5) is placed on the precise electronic scale (6), and a liquid ring device (8) is installed at the bottom of the supergravity centrifuge main body (7); the liquid to be discharged area (3) is communicated with a closed liquid storage tank (5) through a liquid pipe in a test end hanging basket (1), the closed liquid storage tank (5) is connected with a liquid ring device (8) through an air pipe, and is connected to one end of a proportional control valve (9) through the liquid ring device (8), the other end of the proportional control valve (9) is connected with a vacuum regulation system (10), and a pressure gauge (4) is installed in the vacuum regulation system (10);
the proportion regulating valve (9) and the vacuum regulating system (10) are arranged in a normal gravity environment, and the rest devices are arranged in a supergravity environment.
2. The fluid discharge control device of claim 1, wherein: the air pipe extends out of the test end hanging basket (1) and is connected to the liquid ring device (8) after passing through a rotating arm and a rotating shaft of the hypergravity centrifuge.
3. The fluid discharge control device of claim 1, wherein: the area (3) to be drained is placed in the centrifugal model (2) by a container, and liquid is contained in the container.
4. The fluid discharge control device of claim 1, wherein: the upper end of the liquid area (3) to be discharged is provided with a port as a liquid outlet, and the port is communicated with the closed liquid storage tank (5) through a liquid pipe.
5. The fluid discharge control device of claim 1, wherein: the air vent of the closed liquid storage tank (5) is connected to one port of the liquid ring device (8) through an air pipe, and then is connected to the vacuum regulation system in the normal gravity environment through another section of pipeline by means of the other port of the liquid ring device (8).
6. A liquid discharge control method of a supergravity centrifugal model applied to the device of any one of claims 1 to 5, characterized in that: the method specifically comprises the following steps:
s1, establishing a liquid quality control parameter Z of the closed liquid storage tank (5)1And vacuum requirement control parameter Z2；
S2, before the super-gravity centrifuge works, the liquid quality control parameter Z of the closed liquid storage tank (5) meeting the requirement of S1 is enabled to be met through adjusting the vacuum adjusting system (10) of the normal gravity environment in real time1And vacuum requirement control parameter Z2；
S3, under the working condition of the hypergravity centrifuge, monitoring the state change of the centrifugal model (2) in the hypergravity environment in real time according to the vacuum adjusting system (10), and controlling the parameter Z according to the liquid quality of the closed liquid storage tank (5) of S11And control of vacuum degreeSystem parameter Z2And (5) judging and checking the test until the test is satisfied.
7. The liquid discharge control method of the supergravity centrifugal model according to claim 6, characterized in that: and in S1, controlling the liquid quality Z of the sealed liquid storage tank1And vacuum degree control parameter Z2The method specifically comprises the following steps:
liquid quality control parameter Z1Expressed as the following relationship:
Z1＝ΔM/Δt
wherein Z is1The liquid quality control parameter of the closed liquid storage tank (5) is represented, and the delta M is the variation of the liquid quality in the closed liquid storage tank (5) within a preset time interval delta t;
vacuum degree control parameter Z2Expressed as the following relationship:
Z2＝ΔP
wherein Z is2The vacuum degree control parameter of the closed liquid storage tank (5) is shown, and delta P is the vacuum pressure difference of the vacuum adjusting system (10) in the normal gravity environment.
8. The liquid discharge control method of the supergravity centrifugal model according to claim 6, characterized in that: the S2 specifically includes:
s2.1, controlling the parameter Z according to the preset liquid quality1And the upper and lower limit error of liquid mass Delta Z1Establishing a liquid quality control range Z1-ΔZ1～Z1+ΔZ1；
S2.2, performing vacuum pumping work by the vacuum regulating system (10) according to preset pumping flow, simultaneously controlling the opening of the proportion regulating valve (9), and regulating the vacuum difference in the closed liquid storage tank (5) in advance;
the method is characterized in that manual adjustment is utilized to adjust the experience value in advance, then the system enters an automatic adjustment link, and because real-time closed-loop feedback automatic adjustment needs to be realized finally, the manual adjustment is performed in advance to reach a relatively close experience value, so that the automatic adjustment link can achieve dynamic balance in a relatively short time;
s2.3, detecting the mass change quantity delta M of the liquid in the closed liquid storage tank (5) in real time through a precise electronic scale (6) at the bottom of the closed liquid storage tank (5), and calculating the liquid discharge rate delta M/delta t of the liquid in the closed liquid storage tank (5) according to the real-time liquid mass change quantity delta M;
s2.4, according to the drainage rate delta M/delta t obtained in real time and the set liquid quality control parameter Z1The control feedback of the vacuum regulating system (10) adjusts the pumping flow of the vacuum regulating system (10) and the opening degree of the proportion regulating valve (9) in real time, so that the liquid discharge rate delta M/delta t is in the liquid quality control range Z1-ΔZ1～Z1+ΔZ1And (4) the following steps.
9. The liquid discharge control method of the supergravity centrifugal model according to claim 6, characterized in that: the S3 specifically includes:
s3.1, controlling a parameter Z according to preset vacuum degree2And vacuum degree control upper and lower limit error delta Z2Establishing a vacuum control range Z2-ΔZ2～Z2+ΔZ2；
S3.2, performing vacuum pumping work by the vacuum regulating system (10) according to preset pumping flow, simultaneously controlling the opening of the proportion regulating valve (9), and regulating the vacuum difference in the closed liquid storage tank (5) in advance;
s3.3, feeding back the vacuum pressure of the vacuum adjusting system (10) in real time through a pressure gauge (4) at the top of the closed liquid storage tank (5) to obtain a vacuum pressure fluctuation change value delta P/delta t in unit time;
s3.4, obtaining the change value delta P/delta t of vacuum pressure fluctuation and the set vacuum degree control parameter Z in real time2Comparing feedback, and adjusting the pumping flow of the vacuum adjusting system (10) and the opening of the proportional adjusting valve (9) in real time to ensure that the vacuum pressure fluctuation variation value delta P/delta t is in the vacuum degree control range Z2-ΔZ2～Z2+ΔZ2And (4) the following steps.
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