TWI452267B - Tdr apparatus and method for liquid level and scour measurements - Google Patents

Description

Time domain reflective liquid surface and brush depth measuring device and method thereof

The invention relates to a device and a method for simultaneously measuring liquid level and brush depth behavior, in particular to a measuring device for measuring liquid level and brush depth by using time domain reflectometry (TDR) The method is used to simultaneously monitor the change in liquid level and scouring depth.

Time Domain Reflectometry (TDR) is an electromagnetic wave sensing technology. The electromagnetic wave transmission system includes a coaxial cable and a waveguide as an extension cable. The waveguide is an extension of the coaxial cable and serves as a signal transmission and transmission. The sensing component, the waveguide is designed to convert the environmental change of the desired monitoring into the transmission impedance change of the sensing waveguide, so that the environmental variation parameter can be known by the reflected signal. The waveguide is a waveguide that extends electromagnetic waves from the coaxial cable into the medium to be tested. The TDR water content waveguide is usually composed of two or three conductor rods. For example, Yu and Yu (2010) propose three conductor types, while Yankielun and Zabilansky (1999) propose the TDR erosion wave guide type. The root steel tube forms a sensing waveguide. The above technology is similar to the general TDR water content waveguide, but the size is large. When used in the field, a steel pipe can be installed on the bottom of the waveguide (US Patent # 6,909,669). Other related US patents are also based on the same concept. For example, U.S. Patents 6,541,985, 6,121,894, 6,100,700 and 5,784,338, and the like. However, the above-mentioned types are applied in practice, especially in Taiwan, and the following potential problems still exist:

First, the transmission distance caused by signal attenuation:

Generally, river water and riverbed have a certain degree of electrical conductivity, and the conductivity will cause the electromagnetic wave transmission to decay with distance. Therefore, the general soil water content of the waveguide is rarely more than 1 meter. If a waveguide similar to soil water content is directly used, The scouring sensing range is bound to be quite limited and is not suitable for many rivers in Taiwan. The observation of the violent scouring. Yankielun and Zabilansky (1999) and Yu and Yu (2010) proposed a preliminary test of the waveguide, which can be found that the signal attenuation increases with the increase of water depth. It is expected that if the waveguide and the water depth exceed 2 meters, the water-soil interface and the guide The reflected signal at the end of the wave will be difficult to distinguish.

Second, the installation practice and impact resistance issues:

The above-mentioned type of soil water-conducting wave guide is not suitable for installation of in-situ flushing monitoring. In the alluvial riverbed, a steel pipe can be installed at the bottom of the wave guide to drive through, but it is not suitable for gravel or rocky riverbed applications, and when scouring When the sensing range is more than 3 meters, the waveguide must be segmented and connected in the field. These installation practical issues need to be considered. In addition, the above-mentioned rigid sensor has an impact resistance in a river environment with a mixed stone and a high flow velocity, and particularly when the brush depth is deep, it may be easily deformed and damaged.

Third, the scouring depth of the signal analysis algorithm:

The TDR measures the reflected signal generated by the joint, the water-soil interface and the end of the waveguide. When the water level is lower than the top of the TDR waveguide, there is still a reflection signal at the air-water interface. In such a complex reflection signal, the scouring signal is determined. Depth is not an easy or easy to automate job. If the electromagnetic wave is transmitted from bottom to top, it can ensure that there is no reflection signal at the air-water interface before the water-soil interface is reflected. The water-soil interface reflection signal is easier to distinguish, but such a configuration will increase the difficulty of installation of the waveguide. . If the electromagnetic wave is from top to bottom and when the water level is lower than the top of the waveguide, the joint, the air-water interface reflection and the multiple reflection between the water-soil interface will cause the water-soil interface to reflect the signal more difficult. Resolve. Based on the above analysis complexity, it is impossible to provide an automated and efficient analysis and calculation process stably and quickly.

In view of this, the present invention provides a time domain reflective liquid level and brush depth measuring device and a method thereof Law to improve the above-mentioned deficiency.

The main object of the present invention is to provide a time domain reflective liquid level and brush depth measuring device, which simultaneously measures the liquid surface and the brush depth behavior by using the time domain reflection method, thereby simultaneously monitoring the liquid surface and the scouring depth change. Combined with the design of the waveguide of similar anchor cable, the design conforming to the installation practice is proposed, and the conductor insulation treatment is considered to solve the signal attenuation problem.

Another object of the present invention is to provide a time domain reflection type liquid level and brush depth measurement method, which is a signal analysis algorithm for measuring liquid level and scouring depth, and the invention combines different electromagnetic wave speeds based on different media. Reflective signal identification and wave velocity calibration and analysis process, a more reliable signal analysis algorithm is proposed.

In order to achieve the above object, the time domain reflective liquid level and brush depth measuring device of the present invention is installed in a environment to be monitored to monitor the change of liquid level and scouring depth, and the measuring device for the liquid surface and the brush depth The invention comprises at least one coaxial cable, which uses a transit probe to connect a time domain reflective metal sensing waveguide, and the coaxial cable transmits an electromagnetic pulse wave generated by a time domain reflectometer to the metal sensing waveguide. Receiving electromagnetic pulse waves and generating a reflection signal according to the depth change and transmitting back to the coaxial cable to transmit back to the time domain reflectometer by using the coaxial cable; and having at least one anchor connected to the metal sensing waveguide end to fix Metal sensing waveguide.

Another embodiment of the present invention is a time domain reflective liquid level and brush depth measurement method, which utilizes the aforementioned liquid level and brush depth measuring device to measure the liquid level and the scouring depth of the environment to be monitored. The measuring method comprises the following steps: First, measuring the waveform of a known liquid level and water depth by using a measuring device as a reference waveform, and obtaining a wave velocity of the air segment and a wave velocity of the clear water segment through a calibration step and The velocity of the silt soil; the re-measurement device is taken from the environment to be monitored A measurement waveform is measured, and the time difference between the travel time position of the water level surface and the travel position of the reference water level surface of the reference waveform is measured, and the known air segment wave velocity is used to obtain the amount. The liquid level corresponding to the waveform and the depth of the liquid surface (the total depth of the clear water and the silt); finally, the position of the end point is obtained in the measurement waveform, and the position of the water level surface, the depth of the liquid surface, and the clean water are measured. The segmental wave velocity and the velocity of the silt soil segment calculate the actual position of the interface between the clear water segment and the silt soil in the environment to be monitored, and then obtain the erosion change of the environment to be monitored.

The purpose, technical contents, features and effects achieved by the present invention will be more readily understood by the detailed description of the embodiments and the accompanying drawings.

The invention provides a measuring device and a method for measuring liquid level and brush depth by using Time Domain Reflectometry (TDR). TDR technology is an emerging monitoring technology that uses its principles to design different waveguides (Waveguides, or detectors) that can monitor different physical quantities. The invention proposes countermeasures for using TDR to monitor the problems encountered in flushing. Firstly, in the design of the waveguide, a design similar to the anchoring cable design is proposed, and the design conforming to the installation practice and the impact resistance is proposed, and the waveguide insulation treatment is considered. Solving the problem of signal attenuation; in terms of measurement methods, the electromagnetic wave velocity is also significantly different due to the different dielectric coefficients of air, water and formation. The present invention combines the identification of reflected signals and the calibration and analysis of electromagnetic wave speed to provide a more reliable signal analysis. Algorithm.

The present invention discloses a liquid level and brush depth measuring device using a time domain reflection technique and a method thereof, wherein some of the definitions, detailed manufacturing or processing processes for electromagnetic waves or wave guides and the like are utilized, and the prior art is utilized. To achieve this, it is not fully described in the following description. Moreover, the drawings in the following texts are not completely drawn in accordance with actual relevant dimensions, and their function is only to show a schematic diagram relating to the features of the present invention.

The first figure is a schematic diagram of the structure of the liquid level and brush depth measuring device of the present invention. Please refer to the first figure. The measuring device for the liquid level and the brush depth includes a time domain reflective metal sensing waveguide 10 The TDR extraction system 12, the anchor 14 and a holder 16 and the like; the top of the time domain reflective metal sensing waveguide 10 is fixed to the top of the bridge 18 or the pier base by the fixture 16 to the environment to be monitored. The bottom of the time domain reflective metal sensing waveguide 10 can be matched with the general drilling equipment to drill a hole 20 at a predetermined position of the river bed, and the time domain reflective metal sensing waveguide 10 is placed and fixed for use. The field reflective metal sensing waveguide 10 is connected to the anchor 14 at the end of the bottom of the hole 20 to be fixed with the anchor 14. The sensing waveguide 10 is fixed by the pouring mixed soil, and the anchor is fixed. The 14 series can be metal, non-metal or composite material; the gap between the river bed surface and the anchor 14 is backfilled with the backfill 22 to simulate the sedimentation depth of the original river bed, thereby providing flushing measurement.

The architecture of the TDR capture system 12 is also shown in the second figure. The TDR capture system 12 includes at least one coaxial cable 24 electrically connected to the time domain reflective metal sensing waveguide 10 and utilized. The coaxial cable 24 is connected to a coaxial cable multiplexer 26 and a time domain reflectometer 28, and the domain reflector 28 is electrically connected to the coaxial cable multiplexer by using the control line 30. 26 and a data capture system 32.

Furthermore, a preferred embodiment of the time domain reflective metal sensing waveguide 10 for use in the measuring device of the present invention is shown in the third figure, the coaxial cable 24 and the time domain reflective metal sensing waveguide. 10 is connected to each other by a switching probe 34, which is electrically connected to the coaxial cable to receive the electromagnetic pulse wave, and monitor the environmental change, and thereby generate a reflection signal; the time domain reflective metal sense The structure of the measuring waveguide 10 is a multi-bar type of at least two metal rods or a multi-cable type of at least two metal cables to respectively serve as positive and negative passages for conducting electromagnetic pulse waves or reflecting electromagnetic pulse waves, and metal sensing. The end boundary of the waveguide 10 is a broken-circuit connection or a short-circuit connection, and the cross-sectional shape is a circle, an ellipse or an arbitrary polygon, etc.; and the surface of the metal sensing waveguide 10 is coated on the outer surface of at least one channel. There is an insulating layer; as shown in the third figure, here two metal cables are taken as an example, including a multi-core steel strand cable 102, a steel cable 104, and covered by a multi-core steel strand cable 102. The insulating layer 106 is mainly constructed by transmitting the inner and outer conductors thereof through the coaxial cable 24. The wire 342 in the probe 34 is electrically connected to the multi-core steel cable 102 and the steel cable 104. The adapter further includes a metal or other conductive material casing 344 having an insulating or non-conductive material filling material. 346 fixed coaxial cable 24 and multi-core steel stranded cable 102 and steel cable 104. The outer casing 344 is mainly used to protect the conversion joint 34 and shield the internal leakage electric field factory to reduce the interference caused by leakage electromagnetic field. The multi-core steel stranded cable 102 and the steel cable 104 provide positive and negative passages for electromagnetic wave conduction, and the multi-heart steel stranded cable 102 can be selected according to the installation environment of the site, and the design tension is in accordance with the design tension strength. The integral time domain reflective metal sensing waveguide 10 is protected for use; the insulating layer 106 protects the multi-core steel stranded cable 102 and the steel cable 104 from rust, and can block the conductivity of the water body and reduce the electromagnetic wave energy loss. .

Please refer to the first, second and third figures at the same time, the time domain reflective metal sensing waveguide 10 is connected to the coaxial cable 24, and then sequentially connected to the coaxial cable multiplexer 26; the time domain reflectometer 28 is The electromagnetic pulse wave is emitted and receives the reflection signal of the time domain reflective metal sensing waveguide 10, and the reflection signal can further analyze the electromagnetic wave in the time domain reflective metal sensing waveguide 10 to encounter different external media (air and water) The reflection signal is switched by the coaxial cable multiplexer 26, and the time domain reflectometer 28 can be connected to a plurality of different time domain reflective metal sensing waveguides 10 to provide the advantages of TDR multi-point layout.

The preferred waveform of the electromagnetic wave in the time domain reflective metal sensing waveguide is preferably shown in the fourth figure, and the fourth (a) is the time domain reflective metal sensing waveguide in the actual amount. Schematic diagram of the time measurement, since the dielectric constant of air is 1, the dielectric constant of water is 81, so the electromagnetic wave has obvious reflection signals in the interface between the two, and when the electromagnetic wave reaches the bottom of the metal sensing waveguide (open type) , there is a clear positive reflection signal, as shown in the fourth (b). However, limited by the difference in the dielectric coefficient between water and submerged silt, the TDR reflection waveform is smoothed by the cable resistance (ie, the length of the extension cable), or external water and siltation. Under the influence of soil conductivity, the interface between water and silt soil is not easy to be clearly interpreted, and the location of silt soil cannot be directly provided from this position, that is, it cannot reflect the change of flushing.

Therefore, in order to avoid this problem, in addition to the above-described measuring device, the present invention also proposes a measuring method corresponding to the flushing analysis. In the measuring method of the present invention, the electromagnetic wave reflection signal generated by the sensing device in different material interfaces is mainly used, and the system parameter calibration and measurement program of the established scouring sensing waveguide device is utilized. After the analysis, wash the changes. Therefore, before the method of the present invention is fully described, the flow of the calibration step is described in detail as follows:

First, referring to the fifth (a) diagram, the TDR first measurement waveform of a known correlation configuration can be obtained in the field or indoor by using the above-mentioned measuring device, and can be set as a reference waveform, and the related configuration system is known. Contains the start position of the wave guide waveform t ₀ (can be a cable joint or other artificially defined fixed position), the reference water level travel time position t _{a / w, r} and the corresponding liquid level depth (clear water and silt soil total Depth) L _a/w,r , the position of the waveguide end point t _e,r , the depth of the clear water section L _w,r and the depth of the silt section L _s,r .

Continuing, based on the aforementioned reference waveform, the second measurement waveform of another set of different water levels can be reused, as shown in the fifth (b) of the preferred embodiment, and the water level travel time position t _{a is} calculated. _/w,m , between the known and reference waveform water level difference ΔL _a , the air segment wave velocity V _a can be calculated based on the following equation (1):

Finally, based on the aforementioned reference waveform, at least one second measurement waveform under different water levels may be additionally provided, and the water level surface travel time t _a/w,m of the measurement waveform and the waveguide end point travel time are calculated. The position t _e,m , and the corresponding clear water depth L _W,m , and the silt depth L _{s,m are provided} , and the preferred embodiment is as shown in the fifth (b) diagram, using the reference waveform (the first amount) The two sets of data of the measured waveform and the second measured waveform can be calculated based on the following equation (2), and by this simultaneous equation, the wave velocity V _w of the clear water segment and the wave velocity V _{s of the} silt soil can be calculated:

At this point, the entire calibration process is completed, and by the above calibration step, the air segment wave velocity V _a associated with the measuring device, the clear water segment wave velocity V _{w ,} and the silt soil segment wave velocity V _{s can be provided} .

After explaining the complete calibration process, the detailed process of the actual scouring measurement method of the present invention is described as follows: First, the above calibration step can be directly followed or re-executed, as shown in the fifth (a) diagram, which can be obtained on the spot. A TDR measurement waveform of a known related configuration is set as a reference waveform, and the related configuration includes a metal sensing waveguide waveform starting point travel time t ₀ , a reference water level surface travel time position t _{a/w, r,} and a corresponding The depth of the liquid surface (the total depth of clear water and silt) L _a/w,r , the position of the metal sensing waveguide waver t t _{, r} , the depth of the clear water L _{W, r} , and the depth of the silt _s,r .

Continuation, based on the aforementioned reference waveform, the measurement waveform analysis can be performed. As shown in the fifth (b) diagram, the water level surface travel time t _{a/w,m is} first calculated _, and the known air segment wave velocity V _a , Then, based on the foregoing equation (1), the water level difference ΔL _a from the reference waveform can be calculated, that is, the corresponding liquid surface depth (water and soil depth) L _a/w,m of the measured waveform is obtained.

Finally, the measured water level surface travel time position t _{a / w, m} and the corresponding liquid surface depth L _{a / w, m} calculated by the above steps, in addition, the metal sensing waveguide waveform end point can be calculated according to the measured waveform When the time position t _e,m , together with the known wave velocity V _{w of the} clear water section and the wave velocity V _{s of the} silt section, the following equation (3) can be used to calculate the depth L _{s,m of the} silt section during the measurement. Corresponding to the reference (initial) waveform silt depth L _s,r , the actual position of the interface between the clear water section and the silt soil section in the environment to be monitored can be known, and the wash change of the environment to be monitored can be obtained.

In summary, the measuring device and method of the present invention mainly uses the time domain reflection method to simultaneously measure the liquid surface and the brush depth behavior, thereby simultaneously monitoring the change of the liquid surface and the scouring depth, and the fitting device adopts a guide which is similar to the anchor cable. Wave filter design, proposed to meet the installation practice design, and consider the conductor insulation treatment to solve the signal attenuation problem. In addition, the invention combines the reflection signal identification and the wave velocity calibration and analysis process, which is a fairly reliable signal measurement method.

The embodiments described above are merely illustrative of the technical spirit and the features of the present invention, and the objects of the present invention can be understood by those skilled in the art, and the scope of the present invention cannot be limited thereto. That is, the equivalent variations or modifications made by the spirit of the present invention should still be included in the scope of the present invention.

10. . . Time domain reflective metal sensing waveguide

102. . . Multi-core steel cable

104. . . Steel cable

106. . . Insulation

12. . . TDR capture system

14. . . Anchor

16. . . Holder

18. . . bridge

20. . . Hole

twenty two. . . Backfill

twenty four. . . Coaxial cable

26. . . Coaxial cable multiplexer

28. . . Time domain reflectometer

30. . . Control line

32‧‧‧Information Capture System

34‧‧‧Transfer probe

342‧‧‧Wire

344‧‧‧Shell

346‧‧‧Filling materials

The first figure is a schematic diagram of the structure of the liquid level and brush depth measuring device of the present invention.

The second figure is a schematic diagram of the architecture of the TDR capture system used in the present invention.

The third figure is a schematic structural view of a time domain reflective metal sensing waveguide used in the present invention.

The fourth (a) diagram is a schematic diagram of the present invention using the time domain reflective metal sensing waveguide in actual measurement.

The fourth (b) diagram is a schematic diagram of the waveform measured by the metal sensing waveguide in the present invention.

The fifth (a) diagram and the fifth (b) are schematic diagrams of the analysis of the time-domain reflective metal sensing waveguides of the measurement waveforms respectively in different environments.

10. . . Time domain reflective metal sensing waveguide

12. . . TDR capture system

14. . . Anchor

16. . . Holder

18. . . bridge

20. . . Hole

twenty two. . . Backfill

Claims (16)

A time domain reflective liquid level and brush depth measuring device is installed in a environment to be monitored to monitor changes in liquid level and scouring depth. The liquid level and brush depth measuring device comprises: at least one coaxial cable Transmitting an electromagnetic pulse wave; at least one time domain reflective metal sensing wave guide electrically connected to the coaxial cable to receive the electromagnetic pulse wave, and monitoring the depth change, and generating a reflection accordingly a signal; at least one anchor connected to the end of the metal sensing waveguide, the anchor is embedded in the environment to be monitored to fix the metal sensing waveguide; and at least one switching probe Connecting the coaxial cable and the metal sensing waveguide, wherein the switching probe further comprises: a casing to cover a portion of the coaxial cable connected to the metal sensing waveguide; and a filling The material is located inside the casing and filled up. The time domain reflective liquid level and brush depth measuring device according to claim 1, wherein the metal sensing waveguide is configured by a multi-bar type of at least two metal rods or a multi-cable type of at least two metal cables. To respectively serve as the positive and negative channels that conduct the electromagnetic pulse wave. The time domain reflective liquid level and brush depth measuring device of claim 2, wherein at least one of the outer surfaces of the channel of the metal sensing waveguide is further covered with an insulating layer. The time domain reflective liquid level and brush depth measuring device according to claim 2, wherein the end boundary of the metal sensing waveguide is a broken connection or a short circuit connection. The time domain reflective liquid level and brush depth measuring device according to claim 2, wherein the metal rod or the metal cable has a circular, elliptical or arbitrary polygonal cross section. The time domain reflective liquid level and brush depth measuring device according to claim 1, wherein the anchor is Metal, non-metal or composite. The time domain reflective liquid level and brush depth measuring device according to claim 1, wherein the filling material is a non-conductive material. The time domain reflective liquid level and brush depth measuring device of claim 1, wherein the outer casing is made of metal or other conductive material. The time domain reflective liquid level and brush depth measuring device according to claim 1, wherein the anchor and the end of the metal sensing waveguide are embedded in a river bed hole of the environment to be monitored, and utilize one The backfill fills the hole to simulate the depth of the original riverbed deposit in the environment to be monitored. The time domain reflective liquid level and brush depth measuring device according to claim 1, further comprising a fixture for fixing the metal sensing waveguide to the bridge or the pier base of the environment to be monitored. The time domain reflective liquid level and brush depth measuring device according to claim 1, wherein the time domain reflective metal sensing waveguide is further connected to a coaxial cable multiplexer through the coaxial cable to utilize The coaxial cable and the coaxial cable multiplexer connect two or more of the metal sensing waveguides to a time domain reflectometer. A time domain reflective liquid level and brush depth measurement method according to claim 1, wherein the liquid level and the brush depth measuring device are used to measure the liquid level and the scouring depth of the environment to be monitored, The liquid level and brush depth measuring method comprises the following steps: measuring the waveform of a known liquid level and water depth by using the liquid level and the brush depth measuring device as a reference waveform, and the liquid level and the brush depth measuring device The calibration step has been used to know the wave velocity of the air segment, the wave velocity of the clear water segment and the wave velocity of the silt soil. The liquid level and the brush depth measuring device are used to obtain a measurement waveform from the environment to be monitored. Measuring the measured position of the measured waveform and the reference water level of the reference waveform Set the travel time difference, and then use the air segment wave velocity to obtain the liquid surface depth corresponding to the measurement waveform; and obtain an end travel time position according to the measurement waveform, and cooperate with the measurement water level surface travel time position, The liquid level depth, the wave velocity of the clear water section and the wave velocity of the silt section calculate the actual position of the interface between the clear water section and the silt section in the environment to be monitored. The time domain reflective liquid level and brush depth measuring method according to claim 12, wherein the calibration step of the liquid level and the brush depth measuring device further comprises: obtaining the liquid for measuring the known liquid level and water depth The first measurement waveform of the surface and the deep sensing device, and the second measurement waveform of the liquid surface and the brush depth sensing device of at least another set of different liquid level positions and water depths is obtained, by the first quantity The time domain reflection travel time difference between the measured waveform and the liquid level position of the second measured waveform determines the wave velocity of the air segment of the liquid level and the brush depth sensing device; and the first measured waveform and the second The end position of the measurement waveform and the travel position of the water level surface, together with the known liquid level and water depth of the first and second measurement waveforms, can be calibrated to obtain the clear water wave of the liquid level and the brush depth sensing device Transmission speed and the velocity of the silt section. The time domain reflective liquid level and brush depth measurement method according to claim 13, wherein the wave velocity of the clear water section and the wave velocity of the silt soil section are obtained by using the following equation: Where V _{w is} the wave velocity of the clear water section, and V _{s is} the wave velocity of the silt soil section, the water level surface of the first measurement waveform is t _{a/w, r} and the end position is t _{e , r} , the depth of the clear water section is L _{w, r} and the depth of the silt section is L _s,r , the travel position of the water level surface of the second measurement waveform is t _{a/w, m} , and the travel position of the end point is t _{e, m} , the depth of the clear water section is L _{w, m} and the depth of the silt section is L _s,m . The time domain reflective liquid level and brush depth measurement method of claim 13 or 14, wherein the first measurement waveform is the reference waveform. The time domain reflective liquid level and brush depth measurement method according to claim 12, wherein calculating the actual position of the clear water section and the silt soil section in the environment to be monitored utilizes the following equation: Where V _{w is} the wave velocity of the clear water section, and V _{s is} the wave velocity of the silt soil section, the water level surface travel position of the measurement waveform is t _{a/w, m} , and the end travel time position is t _e,m The depth of the liquid surface L _a/w,m and the depth of the silt section are L _s,m .