CN113624198A - Method and system for measuring vertical displacement of structure in real time based on pressure wave conduction - Google Patents
Method and system for measuring vertical displacement of structure in real time based on pressure wave conduction Download PDFInfo
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- CN113624198A CN113624198A CN202010382960.4A CN202010382960A CN113624198A CN 113624198 A CN113624198 A CN 113624198A CN 202010382960 A CN202010382960 A CN 202010382960A CN 113624198 A CN113624198 A CN 113624198A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
- G01C5/00—Measuring height; Measuring distances transverse to line of sight; Levelling between separated points; Surveyors' levels
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
- G01C5/00—Measuring height; Measuring distances transverse to line of sight; Levelling between separated points; Surveyors' levels
- G01C5/04—Hydrostatic levelling, i.e. by flexibly interconnected liquid containers at separated points
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M5/00—Investigating the elasticity of structures, e.g. deflection of bridges or air-craft wings
- G01M5/0008—Investigating the elasticity of structures, e.g. deflection of bridges or air-craft wings of bridges
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M5/00—Investigating the elasticity of structures, e.g. deflection of bridges or air-craft wings
- G01M5/0075—Investigating the elasticity of structures, e.g. deflection of bridges or air-craft wings by means of external apparatus, e.g. test benches or portable test systems
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Abstract
The invention discloses a method and a system for measuring vertical displacement of a structure in real time. The system consists of two parts, namely a pressure sensor distributed at a plurality of measuring points and a liquid pipeline connected with the pressure sensor. The pressure sensor measures the absolute pressure of the liquid in real time. The flexible fluid conduit transmits pressure waves created by the external disturbance to the plurality of sensors at the speed of sound. The pressure sensors of the multiple measuring points measure pressure values at the same moment, errors caused by external interference are eliminated after subtraction, then pressure component amplitude caused by gravity acceleration in the difference value is extracted through Fourier transform, and the pressure component amplitude is divided by liquid density and gravity acceleration to serve as vertical height difference between the two measuring points. Simple structure, pipeline sealing, no liquid volatilizees, and the error that external disturbance brought can be offset to the system characteristic. The static vertical displacement of the structure can be measured, and various frequency component amplitudes of the dynamic displacement can be directly obtained to obtain the dynamic deflection of the structure.
Description
Technical Field
The invention relates to the technical field of structural deformation monitoring, in particular to a method and a system for monitoring structural deformation in real time based on the principle of conduction of pressure waves in liquid.
Background
In order to monitor the safety performance of a building structure, the vertical displacement changes of the structure need to be monitored. Slow vertical displacement is called settlement for short, such as displacement in the slow vertical direction of piers and buildings. Dynamic vertical displacement, some of which are simply referred to as deflection, such as vertical displacement of a bridge under the action of live loads of vehicles and the like and vertical displacement of a track under the action of trains and the like, is a key index for judging the safety performance of a structure. The existing monitoring method and equipment mainly comprise: 1. a measurement method based on an automatic total station; 2. a machine vision based measurement method; 3. a measurement method based on microwave radar; 4. a static level gauge based on a liquid communicating pipe method.
The measuring method based on the automatic total station comprises the following steps: under the condition of through vision, a method is fixed, which can automatically turn to the measuring point to emit laser according to a preset program, measure the distance and angle of the laser, and further calculate the displacement of the structure. There are the following disadvantages: 1. at the same time, the displacement of only one measuring point can be measured; 2. the dynamic displacement cannot be measured in real time. The time period of each measurement is long, and the rapid displacement change condition of the structure under the action of the short external force cannot be reflected in real time. Real-time deformation monitoring of high-speed rail tracks as trains pass; 3. the equipment and the measuring point must be viewed; 4. the influence of weather conditions on the laser is great; 5. the equipment is precise and expensive, and a special pier base needs to be built.
The measuring method based on machine vision comprises the following steps: under the condition of looking through, a target for image recognition is installed at a measuring point, a camera, a telephoto lens, a computer and other equipment are installed at a far reference point, and the displacement of the measuring point is obtained by shooting the image of the target of the measuring point and calculating the movement of the target in the image collected by the camera. There are the following disadvantages: 1. the equipment and the measuring point must be viewed; 2. the weather condition has great influence on the image quality, and the work is difficult in severe weather; 3. when the distance is long, an expensive precise telephoto lens needs to be used; 4. image processing requires specialized computer equipment; 5. the installation is unchanged and the price is high.
The measuring method based on the microwave radar comprises the following steps: a microwave radar is arranged on a reference point, a metal corner reflector is arranged at a measuring point, and the phase difference of microwaves returned by the corner reflector is measured to obtain the distance from the reference point to the measuring point. There are the following disadvantages: 1. the equipment is extremely expensive and difficult to use in a single project for a long time; 2. the observation must be carried out between the measuring point and the datum point; 3. only the linear distance between a measuring point and a reference point can be obtained, and the vertical displacement usually needs to be settled by combining with an inclination angle sensor, so that the precision is reduced;
the static level method based on the principle of liquid communicating pipes comprises the following steps: the measurement of vertical displacement is realized by the principle of flow equilibrium of liquid in a communicating vessel under the action of gravity and atmospheric pressure, which is currently the most commonly used method. The main instrument is a hydrostatic level. The static level gauges at the measuring points are respectively connected by an air pipe and a liquid pipe. And acquiring the difference value between the liquid pressure and the gas pressure by a diffused silicon differential pressure type pressure sensor in the static level gauge. When a certain measuring point sinks and displaces, the liquid pressure of the point is increased, and the air pressure on the liquid surface keeps the same air pressure when the liquid surface changes due to the connectivity of the air pipe, so that the liquid level pressure of the measuring point can intuitively reflect the sinking and displacement of the point.
The hydrostatic level method has the following disadvantages: 1. it can only be used in static equilibrium and cannot measure dynamic displacement: when the displacement of the measuring point is changed rapidly due to inertia and viscous damping when the liquid flows, the liquid level vibrates, and the liquid in the liquid pipe generates a water hammer effect, so that the pressure difference obtained by the pressure sensor is changed violently, and the settlement displacement of the measuring point cannot be reflected accurately and in real time. The method is only suitable for measuring the slowly changing settlement displacement and is not suitable for measuring the dynamic settlement displacement, and if the method cannot be used for measuring the dynamic deflection of the bridge in real time; 2. the differential pressure type diffused silicon pressure sensor has a small measuring range, and the error is 3-5 per mill of the measuring range. The maximum measuring range of a common static level gauge in the market is only 5000mm, and the error at the moment can reach 30-25 mm. Ultrasonic waves are also used to measure liquid level changes. Although the precision of the static level gauge realized by the ultrasonic distance measurement mode is improved in comparison with that of a differential mode, the direct liquid level height is measured, so that the measurement range is limited by the volume and the installation mode, and is only 100-200 mm. This limits the use of hydrostatic levels in situations where large height differentials and high precision settlement displacement measurements are required; 3. the static level has the disadvantages that because a liquid pipe and an air pipe are required to be laid at the same time, the installation is complex, the cost is high, and the wide use of the static level is limited; 4. hydrostatic levels require the use of a water tank to hold water. The inner diameter of the water tank needs to be much larger than the diameter of the water pipe. When the length of the water pipe is changed, the water surface in the water tank is ensured not to be changed greatly. The water in the water tank is connected to one side of each pressure difference type pressure sensor diaphragm by a water pipe; the air above the water level in the water tank is connected to the other side of each differential pressure type sensor diaphragm by an air pipe so that the differential pressure type sensor can measure the air pressure and the water pressure at the two ends of the diaphragm. 4. In practice, a plurality of hydrostatic levels usually form a system. One of the measuring point sensors is used as a reference point, and the pressure difference between the other measuring point sensors and the reference point is compared to convert the pressure difference into corresponding measuring point settlement. When the temperature distribution of the whole system is not uniform, the water density of each measuring point is different, so that the data accuracy is greatly reduced. 5. The various hydrostatic levels are large in size and inconvenient to install. 6. Liquid can evaporate in the operation process, and liquid needs to be added, so that the maintenance is troublesome, and the method is not suitable for long-term monitoring.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a method and a system for monitoring vertical displacement in real time based on the principle that pressure waves propagate in an elastically constrained closed space in all directions of sound velocity. The system can realize self-compensation of system temperature, self-compensation of external mechanical interference and real-time measurement of vertical displacement of a measured object under the motion condition.
According to the invention, the vertical displacement of the measuring point relative to the reference point can be measured in real time only by connecting the reference point with the sensor of the measuring point by the pressure wave reference transmission pipe. No other auxiliary equipment is required. The whole system only consists of a pressure sensor, a pressure transmission pipe and two parts. Simple structure, low cost and convenient use. The use requirement of the structural deformation monitoring project can be better adapted. The combination networking system can realize the field and network remote monitoring and alarm and other extended applications.
In order to achieve the purpose, the invention adopts the technical scheme that: the plurality of containers with built-in pressure sensors are connected with each other by pressure conduction pipes. The pressure transmission pipe is an elastic plastic pipe for transmitting pressure among the pressure sensors. The liquid whose volume is difficult to compress and whose volume is little affected by temperature is selected to fill the pipeline, usually pure water is selected. As shown in fig. 1, the whole system is composed of at least two containers with pressure sensors and a reference transfer pipe. For convenience of description, the container with the pressure sensor is called the pressure wave sensor for short. When the system is filled with water, the atmospheric pressure of the outer wall of the closed plastic pipeline and the liquid pressure in the pipeline form balance. When the pressure wave sensor generates vertical settlement displacement, the water pipe is completely filled with water, so that the volume of the water cannot be changed, and the water cannot flow freely. Setting a pressure sensor at the measuring point 0 as a reference datum point;
when measuring point PiAt rest, measure point PiThe acceleration is equal to the gravitational acceleration g. The water pressure P at the measuring point i is only related to the height H, the density ρ and the acceleration a of the water, namely: p = ρ a H, i.e., H = P/(ρ × a). When the measuring point i sinks from the point a to the point B and the sedimentation displacement Δ Hi occurs, Δ Hi = Δ P/(ρ g) = Hi (t) -Hi (t0) = Δ hi= Hi(t)- Hi(t0)=(Pi(t)- Pi(t0)-(P0(t)-P0(t0))) / (ρg)= （Pi（(t)- P0(t)-（Pi(t0) -P0(t0))）/ (ρg)= （Pi(t)- P0(t)）/ (ρg) -（Pi(t0) -P0(t0) /(. rho.g). Therefore, the vertical displacement of the measuring point i relative to the initial position at the current moment can be obtained only by reading the absolute pressure values of the reference datum point 0 and the measuring point i at the current moment and the initial moment. Wherein Hi (t) is the height difference between the measuring point i at the time t and the reference point 0, Hi (t0) is the height difference between the measuring point and the reference point at the initial time, and Pi(t) is the reading of the pressure sensor at point i at time t, Pi(t0) For measuring the reading of the pressure sensor at the initial moment i, P0(t) is the reading of reference pressure sensor 0 at time t;
when the measuring point is in a moving state, assuming that an additional acceleration value caused by a change in the moving speed is a, the pressure reading of the pressure sensor is pi (t) = ρ g Hi (t) + ρ a h (t). Where h (t) is the height of the water column in the vertical direction of the pressure sensor at time t. In general, because the diameter of the reference transfer tube is only several millimeters, the pressure cavity of the pressure sensor can be made relatively small, and the height of the vertical water column in the cavity is only several millimeters, therefore, when the acceleration caused by the change of the motion speed of the measuring point is not large, the influence of the part can be ignored. However, when the acceleration change of the measuring point is rapid, the part cannot be ignored, and even can be large, so that the reading of the pressure sensor needs to be corrected to correctly reflect the displacement of the measuring point;
from pi (t) = ρ g Hi (t) + ρ a h (t), it can be seen that the pressure value due to the liquid depth is kept constant because the gravitational acceleration g is constant, and the pressure ρ a h (t) due to the motion acceleration is variable. The solution is required to be carried out through a specific algorithm;
the invention adopts the pressure sensor with high sampling frequency, and can read data on a plurality of time sequences of the same pressure sensor in less than one using period. The data of the pressure sensor is converted from the time domain to the frequency domain by discrete fourier transform. In the frequency domain, the amplitude components of various frequency components of the pressure data can be visually distinguished. The Fourier principle shows that: any continuously measured time sequence or signal can be represented as an infinite superposition of sine wave signals of different frequencies. The fourier transform algorithm created according to this principle uses the directly measured raw signal to calculate the frequency, amplitude and phase of the different sinusoidal signals in the signal in an additive manner. By further processing the frequency domain data, information such as signal amplitudes and phases of various frequencies that make up the original data can be presented. Taking the signal amplitude with the frequency of 0, namely the pressure value of the liquid depth, and further converting the signal amplitude into the liquid depth to obtain the vertical dynamic displacement of the dynamic structure; for structures such as bridges, it is often necessary to extract the time phase conditions of the influence of various frequency components on the deflection amplitude and influence of the bridge. The data can be extracted on frequency domain data after Fourier transform according to a required frequency; therefore, the invention can complete the vibration amplitude and phase measurement of the structure under various frequency components only by using the pressure sensor.
The invention can realize self-adaptive temperature compensation, automatically offset the influence caused by external temperature change, and realize high-precision measurement, and the principle is as follows: when the temperature rises, the volume of the water expands and the plastic is sealedThe walls of the pipes constrict, resulting in an increase in the pressure of the water. Assuming that the pressure increases by δ P, according to the principle of the liquid communicating vessel, the pressure at any point in the water body increases by δ P, and δ P = P0(t)-P0(t0). Thus Δ hi = Δ P/(ρ g) = Hi(t)- Hi(t0)= (Pi(t)-δp)- Pi(t0)/(ρg)= (Pi(t)- Pi(t0)- δp)/ (ρg)=(Pi(t)- Pi(t0)-(P0(t)-P0(t0) )/(ρ g). Therefore, due to the closed characteristic of the liquid pipeline, the influence of the temperature on all the pressure sensors in the whole system is the same, and when the pressure is subtracted, the additional pressure influence caused by the temperature can be automatically eliminated, so that the self-adaptive temperature compensation correction is realized, and the influence of the temperature change on the vertical relative displacement of the system measurement is reduced. According to the method, an additional device is not needed, the self-compensation function of the temperature factor can be realized only by the characteristics of the system, the comprehensive cost is saved, and the introduction of errors is reduced; theoretically, if the temperature of water in the pipeline is different, the density of the water is different, and the pressure at each measuring point in the pipeline is different. In practical use, if the temperature of the pipeline is not consistent and a temperature gradient exists, the water will generate convection until the temperature gradient disappears. Within a small range of the same monitoring item, the temperature of the environment is basically consistent. And the length-diameter ratio of the pipeline is very large, which is beneficial to the water temperature in the pipeline to quickly reach the temperature of the external environment. And the volume expansion coefficient of water is very small, so the influence caused by temperature is very small and can be ignored.
The invention can self-adaptively eliminate the influence of external mechanical interference factors and keep the reliability of the measured data. In actual use, each measuring point may be interfered by different external factors, and extra measuring points are generated. For example, there are a plurality of stations spaced apart within a tunnel. When the train passes through each measuring point in sequence, the air pressure in the tunnel can add pressure influence to the liquid pipeline, so that the atmospheric pressure values at each measuring point at the same moment are different. When atmospheric pressure acts on the outer wall of the reference tube made of elastic plastic material, the outside of the tube wall is subjected to the atmospheric pressureThe pressure wave formed by the pressure change is immediately transmitted to the liquid inside the pipe and propagates in the liquid at the speed of sound. Assuming that the atmospheric pressure can increase by δ P, according to the principle of the liquid communicating vessel, the pressure at any point in the water body can increase by δ P, and δ P = P0(t)-P0(t0). Thus Δ hi = Δ P/(ρ g) = Hi(t)- Hi(t0)= (Pi(t)-δp)- Pi(t0)/(ρg)= (Pi(t)- Pi(t0)- δp)/ (ρg)=(Pi(t)- Pi(t0)-(P0(t)-P0(t0) )/(ρ g). The sound propagation in water at normal temperature is about 1500m/s, and under the condition that the distance between each measuring point is not very far, the time of the pressure wave reaching each measuring point is almost the same and can be ignored. When the distance between the measuring points is long, the length of the pipeline can be measured, the time difference of pressure wave propagation under the length is calculated, and the measured pressure data is subjected to time synchronization correction to obtain more accurate vertical displacement data.
When the measuring point is relatively far away, the delay time of the pressure wave can be compensated by an algorithm according to the length of the pipeline. Such as long tunnels, grand bridges and the like: and after the system is installed, knocking the reference transfer pipe beside the reference point by using a tool. The pressure wave generated by the rapping propagates throughout the piping system at the speed of sound. And recording the time of the same pressure wave reaching each pressure sensor so as to perform time synchronization correction on the pressure data of each measuring point.
The invention can eliminate the influence of fine bubbles in the system. Since the liquid in the pipe is closed, when minute bubbles exist in the pipe, the pressure inside the bubbles and the pressure of the liquid are in an equal equilibrium state. When the pressure of the liquid at one end of the bubble changes, the pressure change can be quickly transferred to the liquid in other directions based on the isotropy of the gas, and the new balance is achieved. Therefore, the variation value transmitted by the external interference to each pressure sensor in the whole system is consistent. And the interference can be removed by subtracting the data of the pressure sensors at the measuring points.
The invention has the beneficial effects that: 1. the structure is very simple: the whole system only consists of two parts, namely a closed liquid pipeline and a pressure sensor, and is very convenient to install and use; 2. no through sight is needed between measuring points: the sensors are connected through a flexible closed pipeline, so that vertical displacement changes among the sensors can be measured and can be conveniently arranged on any measuring point; 3. the measurement can be continuously carried out at a plurality of measuring points simultaneously: a sensor is used as a reference, and the vertical displacement continuous measurement of a plurality of measuring points is completed through the closed liquid pipelines which are mutually connected in series; 4. the pressure change brought by the outside is transmitted by the pressure wave in the liquid at the sound velocity, the speed is extremely high, and the displacement with rapid change can be measured. Dynamic deflection caused when a vehicle passes through a bridge and dynamic vertical displacement of a high-speed rail are caused; 5. the time of the pressure wave reaching each measuring point is only related to the mutual distance, so that the distance compensation is easy to realize automatically; 6. interference and influence caused by external change, such as influence of temperature, bubbles, disturbance and the like on vertical displacement of the measuring point can be eliminated only by the structural design of the system without other devices or sensors; 7. the actual displacement of the structure in the motion state can be measured only by carrying out Fourier transform on the data synchronized in time of each sensor without other devices and sensors; 8. the whole system has no movable parts, and the liquid is completely sealed in the pipeline and does not flow or evaporate. Therefore, the system can be used for a long time without maintenance.
Scope of protection and system description of the invention: 1. for convenience and understanding of description, the term "reference transfer tube" as easily understood in this specification is used as a special term to denote a tube having a certain elasticity which is filled with a liquid and closed at both ends. The method is within the protection scope of the invention as long as the method is used, can fill liquid, uniformly transmits external influence in the liquid at a certain speed, and can measure the pressure caused by the influence by a sensor in the system; 2. any structure that transmits pressure waves by using a closed liquid, whether a pipe or a liquid having any properties, or a structure that connects and seals each other, is included in the scope of the present invention. 3. The invention can measure the vertical displacement of the structure in static state and motion. The static displacement can be measured independently, the dynamic displacement can be measured simultaneously, and the displacement components of various frequency components in the dynamic displacement data and the phase in time can be measured simultaneously only according to the data of the pressure sensor without the assistance of other sensors. Which frequency of displacement component and phase is obtained, depending on the needs of the user, does not affect the protection of the invention. 4. The user can adjust the installation mode, the pipeline material, the mode of sheltering from to external climate environment according to actual conditions. The modification can be performed in other ways. However, these improvements are all of perfect nature and do not affect the scope of the invention. 5. In order to minimize the influence of fine bubbles in the liquid pipe on the accuracy, the influence of bubbles of a substance such as an antifoaming agent, which improves the surface tension property of the liquid, on the system may be added to the liquid as an enhancement and supplement to the effect of the present invention. The similar devices for improving the use effect do not influence the protection of the invention. 6. The data generated by the invention can be transmitted by wireless and wired communication modes such as 4G, 5G, Zigbee and the like. The communication mode of data transmission does not influence the protection scope of the invention. 7. The invention uses common pressure sensors in the market to obtain liquid pressure data, such as MEMS pressure sensors, diffused silicon pressure sensors and the like. The protection of the present invention is not affected by whatever sensor is used to obtain the pressure data. 8. The data processing and calculation of the invention adopts a general MCU calculation platform. The appropriate hardware platform and computing resources may be selected according to project requirements. The hardware platform is adopted to complete the data processing, and the protection scope of the invention is not affected.
In the research and development process, the system and the method are used and tested on a plurality of structural deformation monitoring projects, and the system is improved and perfected according to the test result, so that the use effect is good. In order to facilitate the user to fully understand the technical principle and the application method of the present invention, a more general embodiment and two specific industrial embodiments are further described herein:
general examples: 1. installing a pressure wave sensor at a place where vertical displacement needs to be monitored; 2. a pressure wave sensor is arranged at a stable position near the measuring point and is used as a reference; 2. connecting the sensors in series by using a reference tube; 3. injecting water from a water inlet of the pressure sensor, discharging bubbles in the pipeline along with water flow at a water outlet of the measuring point sensor, and sealing the water inlet and the water outlet of the sensor when the bubbles are not visible; 4. measuring the pressure difference between each measuring point sensor and the reference sensor at the moment, and recording the pressure difference as an initial position; 5. measuring the pressure difference between each measuring point sensor and a reference sensor at the same moment, comparing the pressure difference with the pressure difference at the initial position, and performing Fourier transform on the compared data; 6. and 5, taking an amplitude value with the frequency of 0 after Fourier transform on the data in the step 5, namely the vertical displacement of the measuring point at the moment.
Subgrade settlement monitoring example. The phenomena of side wall cracking, water leakage and the like occur on the roadbed in a certain tunnel. And preliminarily judging that partial settlement of the tunnel caused by tunnel penetration under the coal mine tunnel possibly exists. In order to ensure safety, the settlement of the tunnel subgrade needs to be monitored in real time. When the traditional static level gauge is used, the liquid level is oscillated due to the vibration of a train passing by, huge errors and obvious errors occur in settlement data, and the system frequently gives false alarms; the pressure wave system is used for measurement, so that the influence of passing trains is effectively filtered, and a better monitoring effect is obtained. The method comprises the following specific implementation steps: 1. arranging a pressure wave sensor at a position of the tunnel far away from the fracture point as a benchmark reference point; 2. installing a reference pipe along the tunnel drainage ditch; 3. installing pressure wave sensors on the side walls of the drainage ditch on two sides of the road shoulder at the fracture point of the tunnel; 4. connecting the reference tube and the pressure wave sensor in sequence; 5. injecting water from a water inlet of the pressure wave sensor at the reference point until no obvious bubbles exist at a water outlet of the last pressure wave sensor; 6. sealing the water filling port and the water outlet; 7. measuring data of each pressure wave sensor in real time, summarizing the data to a gateway, and performing Fourier transform calculation on the pressure difference between each measuring point and a reference point; 8. and taking the amplitude component with the frequency of 0 after Fourier transform as the data of tunnel settlement.
Dynamic deflection of bridge
The deformation monitoring of a bridge is taken as an example to illustrate the working principle of the system: 1, a pressure wave sensor is installed at a place where the bridge needs to monitor vertical displacement. Installing a pressure wave sensor used as a reference datum at the pier of the bridge; 2. connecting the sensors in series by using a reference tube; 3. injecting water from one end of a sensor water injection port which is used as a reference point at the bridge pier, and sealing the water injection port and the water outlet when bubbles in the pipeline are discharged at the sensor water outlet at the other end of the pipeline along with water flow and are not obviously visible; 4. measuring the pressure difference between each measuring point sensor and the reference sensor at the moment, and recording the pressure difference as an initial position; 5. measuring the pressure difference between each measuring point sensor and a reference sensor at the same moment, comparing the pressure difference with the pressure difference at the initial position, and performing Fourier transform on the compared data; 6. and 5, taking the amplitude value with the frequency of 0 after Fourier transform of the data in the step 5, namely the dynamic deflection value of the measuring point at the moment. Generally speaking, the midspan of the bridge is the place with the largest deflection, and the pressure wave sensor is arranged on the midspan section, so that the maximum deflection of the bridge can be monitored in real time. During installation, the pipeline is arranged on the same straight line as much as possible and the turning radius is increased as much as possible at a certain turning place, so that the loss of pressure waves in the pipeline is reduced as much as possible.
Description of the drawings:
FIG. 1 is a schematic diagram of a system architecture
FIG. 2 is a system schematic
Fig. 3 is a pressure wave sensor installed at a pier as a reference point.
Claims (6)
1. The invention is a method and a device for realizing real-time monitoring of vertical displacement of building structure deformation based on the isotropic propagation principle of pressure waves in liquid; the invention can realize static vertical displacement measurement and dynamic displacement measurement by using a simple device.
2. A system for measuring vertical displacement of a structure according to claim 1, consisting of a pressure sensor and a pressure transfer tube interconnected.
3. A system for measuring vertical displacement of a structure according to claim 1, wherein one of the pressure sensors is used as a reference datum point; and subtracting the pressure value of the reference point from the pressure value of the pressure sensor at the measuring point to calculate the vertical displacement between the measuring point and the reference point.
4. The pressure sensor of claim 2, wherein the absolute pressure sensor is adapted to measure the absolute pressure of the liquid in the pressure transfer tube relative to the vacuum.
5. The pressure transmission reference pipe according to claim 2, which consists of a section of plastic pipe filled with liquid and completely sealed at two ends; the pipeline has elastic deformation capacity and compressive strength greater than standard atmospheric pressure; forming a balanced state under the action of the pressure of the internal liquid and the external atmospheric pressure; when disturbance applied to the pipeline from the outside is transmitted to the liquid in the pipeline, pressure waves are formed; due to the completely closed liquid in the pipeline and the almost incompressible characteristic of the liquid volume, pressure waves are transmitted to all positions in the liquid from the source at the speed of sound, so that the influence of pressure change in the pipeline caused by external disturbance is the same; therefore, when the pressure values of the measuring points and the reference datum points are subtracted, the data influence caused by interference can be counteracted.
6. The pressure sensor according to claim 2, acquiring an absolute pressure value in the pressure transmission pipe according to a certain sampling frequency; performing discrete Fourier transform on the absolute pressure value data to obtain pressure amplitudes of various frequency components; because the gravity acceleration is constant in a small range, the influence on the liquid pressure is also constant, namely the frequency is 0; therefore, the component amplitude with the frequency of 0 is taken as a value for calculating the vertical displacement of the measuring point; respectively calculating pressure values with the frequency of 0 of the measuring point and the reference point, and subtracting the pressure values to obtain a pressure difference value caused by the gravity acceleration between the two sensors; the value is divided by the density and the gravity acceleration of the liquid, and the vertical displacement of the measuring point relative to the reference datum point is obtained.
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| CN117405075A (en) * | 2023-12-11 | 2024-01-16 | 北京智博联科技股份有限公司 | Intelligent settlement monitoring method and system |
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| CN201392265Y (en) * | 2009-02-13 | 2010-01-27 | 重庆交通大学 | Bridge deflection intelligent monitoring device |
| CN103389066A (en) * | 2013-08-08 | 2013-11-13 | 华南理工大学建筑设计研究院 | Method for dynamically monitoring vertical displacement of building |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN201392265Y (en) * | 2009-02-13 | 2010-01-27 | 重庆交通大学 | Bridge deflection intelligent monitoring device |
| CN103389066A (en) * | 2013-08-08 | 2013-11-13 | 华南理工大学建筑设计研究院 | Method for dynamically monitoring vertical displacement of building |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117405075A (en) * | 2023-12-11 | 2024-01-16 | 北京智博联科技股份有限公司 | Intelligent settlement monitoring method and system |
| CN117405075B (en) * | 2023-12-11 | 2024-02-27 | 北京智博联科技股份有限公司 | Intelligent settlement monitoring method and system |
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Application publication date: 20211109 |