CN115405867A - Tunnel fire-fighting water pipeline leakage signal enhancement method and monitoring system - Google Patents

Tunnel fire-fighting water pipeline leakage signal enhancement method and monitoring system Download PDF

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CN115405867A
CN115405867A CN202210975913.XA CN202210975913A CN115405867A CN 115405867 A CN115405867 A CN 115405867A CN 202210975913 A CN202210975913 A CN 202210975913A CN 115405867 A CN115405867 A CN 115405867A
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leakage
amplitude
signal
water
leakage signal
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应迪清
韩霄
汪成立
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Zhejiang University ZJU
Zhejiang Scientific Research Institute of Transport
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Zhejiang University ZJU
Zhejiang Scientific Research Institute of Transport
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17D—PIPE-LINE SYSTEMS; PIPE-LINES
    • F17D5/00—Protection or supervision of installations
    • F17D5/02—Preventing, monitoring, or locating loss
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17D—PIPE-LINE SYSTEMS; PIPE-LINES
    • F17D1/00—Pipe-line systems
    • F17D1/08—Pipe-line systems for liquids or viscous products
    • F17D1/14—Conveying liquids or viscous products by pumping
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17D—PIPE-LINE SYSTEMS; PIPE-LINES
    • F17D5/00—Protection or supervision of installations
    • F17D5/02—Preventing, monitoring, or locating loss
    • F17D5/06—Preventing, monitoring, or locating loss using electric or acoustic means

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  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Health & Medical Sciences (AREA)
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  • Water Supply & Treatment (AREA)
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Abstract

The invention discloses a method for enhancing a leakage signal of a tunnel fire-fighting water pipeline and a monitoring system, and belongs to the field of water pipeline detection. Firstly, collecting vibration signals of a water pipeline before and after pressurization of a water pump; then calculating the amplitude of the vibration signal of the water pipeline before and after the water pump is pressurized, and taking the amplitude difference of the vibration signal as a leakage signal to be detected; and finally, comparing the leakage signal to be detected with a first threshold value, if the leakage signal is greater than the first threshold value, the water pipeline leaks, otherwise, the water pipeline is normal. Research results show that compared with the existing technology of utilizing vibration signals under the condition of constant water pressure, the method provided by the invention can increase the strength of the leakage signals to nearly 3 times under a certain condition, and effectively improves the sensitivity of detecting the leakage of the tunnel fire-fighting water pipeline. Simulation analysis results show that reasonable selection of the vibration signal amplitude difference judgment threshold value is beneficial to reducing the rate of missed judgment of a leakage state and the rate of wrong judgment of a non-leakage state.

Description

Tunnel fire-fighting water pipeline leakage signal enhancement method and monitoring system
Technical Field
The invention relates to the field of water pipe detection, in particular to a method for enhancing a leakage signal of a tunnel fire-fighting water pipe.
Background
With the rapid development of highway tunnels, the problem of tunnel fire safety guarantee is gradually paid attention to. Because the tunnel is relatively closed and narrow relative to other road sections, the entrances and exits are few and far away from each other, so that once a fire disaster happens to the tunnel, great difficulty is caused in avoiding and rescuing, and great economic loss and casualties are easily caused if the fire disaster is not controlled in time. The integrity of tunnel fire-fighting facilities is guaranteed, the prerequisite condition of whether effective fire fighting can be achieved in time after a fire disaster occurs is met, and the requirement of management responsibilities of management units is met. The fire-fighting water pipe is one of important fire-fighting facilities in the tunnel, and the leakage of the water pipe can bring potential safety hazards to the tunnel.
At present, the maintenance of fire-fighting facilities such as water pipelines in highway tunnels is mainly executed according to technical Specification for road tunnel maintenance (JTG H12-2015) issued by the department of transportation, wherein the water supply pipes are required to be overhauled for 1 time when water leaks every 1 to 3 months, in practice, the leakage detection of the water pipelines usually adopts a manual visual inspection mode, so that the state information of the water pipelines has certain lag, the detection data is difficult to trace, and meanwhile, vehicles coming and going in the tunnels can bring certain hidden dangers to the safety of maintainers. Therefore, there is a need to develop a non-manual water pipeline monitoring technique with better real-time performance to solve the above problems.
At present, scholars at home and abroad have proposed various monitoring technologies aiming at the leakage problem of the water delivery pipeline. Lin Tianxiang et al, in 2021, have studied a technique for continuously monitoring leakage for a long time by using amplitude variation of a vibration signal caused by leakage in a water pipeline, and the technique has certain advantages and feasibility in reducing the influence of environmental factors and the like by obtaining the vibration signal of a leakage source through a hydrophone installed in the pipeline. However, in the process of adopting the technology, the background noise of the vibration signal existing in the water pipeline under the non-leakage state can bring certain interference to the detection of leakage: on one hand, the weak vibration signal amplitude change caused by the small leakage hole is likely to be submerged in the background noise, thereby causing the leakage state to be missed; on the other hand, the background noise amplitude is often disturbed by various factors such as environment and the like to generate long-term fluctuation, which may not only cause the detection omission of the leakage state, but also cause the misjudgment of the non-leakage state. In addition, the technology is often required to be implemented under constant water pressure conditions, which often requires the water pump to work uninterruptedly for a long time, increasing the probability of damage to the water pump to some extent.
Disclosure of Invention
In order to solve the technical problem, the invention provides a method for enhancing the leakage signal of the tunnel fire-fighting water pipeline, which utilizes the water pressure difference of the water pipeline in two states when the water pump starts and pressurizes, and realizes the judgment of leakage by monitoring the variation of the amplitude difference of the vibration signal in the two states. The invention detects the amplitude difference of the vibration signal, thereby reducing the influence of the long-term fluctuation of the background noise amplitude on the detection result to a certain extent, and increasing the intensity of the leakage signal by optimizing the water pressure difference, thereby finally improving the signal-to-noise ratio of the detection signal.
In order to achieve the purpose, the invention adopts the following technical scheme:
the invention aims to provide a method for enhancing a leakage signal of a tunnel fire-fighting water pipeline, which comprises the following steps:
step 1: collecting vibration signals of a water conveying pipeline before and after pressurization of a water pump;
and 2, step: calculating the amplitude of the vibration signal of the water pipeline before and after the water pump is pressurized, and taking the amplitude difference of the vibration signal as a leakage signal to be detected;
and 3, comparing the leakage signal to be detected with a first threshold value, if the leakage signal is greater than the first threshold value, leaking the water pipeline, otherwise, the water pipeline is normal.
Further, in step 3, if the leakage signal is greater than the first threshold, the leakage signal to be detected is continuously compared with the second threshold, and if the leakage signal is greater than the second threshold, the large leakage occurs in the water pipeline, otherwise, the small leakage occurs in the water pipeline.
Further, the amplification rate of the leakage signal is optimized by adjusting the minimum set pressure and the maximum set pressure of the water pump; the amplification ratio of the leakage signal is as follows:
Figure BDA0003798047660000021
wherein f is 0 Indicating the minimum set pressure, f set Representing the maximum set pressure and r representing the leakage signal amplification.
The second purpose of the invention is to provide a tunnel fire-fighting water pipeline leakage signal monitoring system, wherein the tunnel fire-fighting water pipeline is divided into a plurality of areas, and each area is provided with a vibration sensor; a water pump is installed at one end of the tunnel fire-fighting water pipeline, and a pressure sensor is installed at the outlet section water pipe of the water pump; the monitoring system comprises:
the state trigger module is used for sending working state instructions of the water pump, wherein the working states of the water pump comprise preparation before starting, pressurization starting and pressurization ending, and correspond to an instruction 1, an instruction 2 and an instruction 3 respectively;
the amplitude detection module is used for sampling a vibration signal of the vibration sensor, performing data processing by combining an instruction sent by the state trigger module, and calculating an amplitude average value of the vibration signal of the water pipeline before and after the water pump is pressurized;
and the leakage judging module is used for receiving the amplitude average value of the vibration signals of the water pipeline before and after the water pump is pressurized, which is sent by the amplitude detecting module, taking the amplitude difference as a leakage signal to be detected, comparing the amplitude difference with a first threshold value, if the leakage signal is greater than the first threshold value, the water pipeline leaks, and otherwise, the water pipeline is normal.
Further, the process of the state trigger module sending the working state instruction is as follows:
when the water pump just starts to enter a preparation state before starting, the state trigger module sends a starting pressurization preparation instruction 1 to the amplitude detection module and the leakage judgment module; when the water pump just enters a starting pressurization state, the state trigger module sends a starting pressurization instruction 2 to the amplitude detection module and the leakage judgment module; when the water pump just enters the pressurizing ending state, the state triggering module sends a pressurizing ending command 3 to the amplitude detection module and the leakage judgment module.
Further, when the amplitude detection module receives the instruction 1 sent by the state trigger module, the amplitude detection module starts to sample the vibration signal of the vibration sensor by taking delta T as a time interval, and takes T as an amplitude extraction period; in each amplitude extraction period T, obtaining the maximum value and the minimum value of the vibration signal obtained by sampling by adopting a comparison method, subtracting the minimum value from the maximum value to obtain the amplitude of each period T, and storing the amplitude of each period T;
when the amplitude detection module receives the instruction 2 sent by the state trigger module, the amplitude detection module stops sampling the vibration signal and calculating the amplitude of each period T, and calculates the amplitude at T p Amplitude average A stored in time period v1 And sending the value to a leakage determination module; wherein, t p Represents the time interval of instruction 1 and instruction 2;
when the amplitude detection module receives an instruction 3 sent by the state trigger module, the amplitude detection module restarts sampling a vibration signal of the vibration sensor by taking delta T as a time interval, and taking T as an amplitude extraction period; in each amplitude extraction period T, obtaining the maximum value and the minimum value of the sampled vibration signals by adopting a comparison method, subtracting the minimum value from the maximum value to obtain the amplitude of each period T, and storing the amplitude of each period T; when the time t elapses p Then, the stored amplitude average value A is calculated v2 And sends the value to the leak determination module.
Further, a second threshold is set in the leakage determination module, if the leakage signal is greater than the first threshold, the leakage signal to be detected is continuously compared with the second threshold, if the leakage signal is greater than the second threshold, large leakage occurs in the water pipeline, otherwise small leakage occurs in the water pipeline.
Compared with the prior art, the invention has the advantages that:
based on the characteristic of the leakage vibration signal of the water pipe in the process of starting and pressurizing the water pump, the invention provides the method for enhancing the leakage signal of the tunnel fire-fighting water pipe by using the amplitude difference of the vibration signal before and after pressurizing the water pump, further realizing the monitoring of the leakage condition of the water pipe and improving the signal-to-noise ratio of useful signals. Research results show that compared with the existing technology of utilizing vibration signals under the condition of constant water pressure, the method provided by the invention can increase the strength of the leakage signals to nearly 3 times under a certain condition, and effectively improves the sensitivity of detecting the leakage of the tunnel fire-fighting water pipeline. Simulation analysis results show that reasonable selection of the vibration signal amplitude difference judgment threshold value is beneficial to reducing the rate of missed judgment of a leakage state and the rate of wrong judgment of a non-leakage state.
Drawings
FIG. 1 is a basic block diagram of a tunnel fire-fighting water pipe system shown in an embodiment of the present invention;
FIG. 2 is a graph showing the relationship between the normalized leakage sound amplitude A' and the time t during the water pump startup and pressurization process, which is obtained through simulation, under the conditions of different leakage hole areas S;
FIG. 3 shows different water pressure differences Δ f obtained by simulation set The relationship between the change quantity delta A' of the normalized leakage sound amplitude signal before and after the water pump is pressurized and the area S of the leakage hole under the condition;
FIG. 4 is a graph showing the difference Δ f between different water pressures at a constant water pressure obtained by simulation set Normalizing the relationship between the leakage sound amplitude A' and the leakage hole area S under the condition;
FIG. 5 shows different minimum set pressures f obtained by simulation 0 Signal amplification rate r and water pressure difference delta f under the condition set The relationship between them.
FIG. 6 is a schematic diagram of a leakage signal monitoring system for a tunnel fire-fighting water pipe according to an embodiment of the present invention;
FIG. 7 is a normalized vibration signal for different leak hole areas obtained by simulation.
Detailed Description
The invention will be further described with reference to the accompanying drawings.
In the embodiment, the basic principle of the invention is explained through theoretical derivation, the characteristics of the technology are analyzed through numerical simulation, a method for enhancing the leakage signal of the tunnel fire-fighting water pipeline and a monitoring system are provided according to the characteristics of the technology, and finally the implementation effect of the invention is demonstrated through numerical simulation.
Fig. 1 is a basic block diagram of a tunnel fire-fighting water pipe system. The system mainly comprises a water pipe, a fire hydrant and a water pump.
The fire hydrant is installed in the water conveying pipeline in the tunnel at intervals of a certain length, so that the water conveying pipeline of the whole tunnel is divided into a plurality of areas with the same length. In order to monitor the vibration signal of the water pipeline, a vibration sensor is installed at the position of the water pipeline near each fire hydrant, so that each section of water pipeline corresponds to one vibration sensor, and distributed monitoring on a subsection area of the vibration signal of the water pipeline is realized.
The water pump is used for providing required water pressure for the water conveying pipeline. In order to obtain the water pressure in the water conveying pipeline in real time, a pressure sensor is arranged at the water conveying pipeline of the outlet section of the water pump. In the working process of the actual water pump, the control system presets the maximum value and the minimum value of the water pressure. And when the water pressure monitored by the pressure sensor is lower than a preset minimum value, the water pump starts to supply water and pressurize, and when the water pressure monitored by the pressure sensor reaches a preset maximum value, the water pump stops supplying water and pressurizing. The whole tunnel fire-fighting water pipe system ensures that the water pressure meets the requirement by the method.
If a water pipe leaks, the leakage acoustic power can be expressed as:
Figure BDA0003798047660000051
in the formula: v is the water flow leakage velocity; ρ is the water flow density at the leakage hole; ρ is a unit of a gradient 0 Is the initial density of the water flow; c 0 The sound velocity of the place where the tunnel is located; l is the size of the leakage hole(ii) a K is a proportionality coefficient; n is a constant between 6 and 8. Assuming constant water flow density, i.e. p 0 Where the sound velocity is a fixed value, the leakage acoustic power can be expressed as:
P W ＝λv n S (2)
in the formula: λ is a constant; s is the leak hole area. According to the bernoulli equation, assuming that the leakage of the fire-fighting water pipe is a small hole leakage problem, the amplitude of the leakage sound can be approximately expressed as:
Figure BDA0003798047660000052
in the formula: mu is a constant; f is the running pressure of the water delivery pipe. In this embodiment, when n is set to 6.4, the amplitude of the leak sound is obtained as follows:
Figure BDA0003798047660000053
to simplify the analysis, the leakage sound amplitude is normalized as:
Figure BDA0003798047660000054
in an actual system, when the pressure sensor monitors that the running pressure F of the water pipe is less than the minimum set pressure F 0 At that time, the water pump is started and the water pipe begins to be pressurized. For the purpose of analysis, assume that the initial pressure of the water pump at the time of start-up is f 0 And the pressure after starting increases linearly with time t, so the operating pressure of the water pipe after the water pump is started can be expressed as:
F(t)＝f 0 +kt (6)
in the formula: and k is the pressure increase coefficient of the water conveying pipeline in unit time under the condition of water pump pressurization. Here, it is assumed that when F reaches the maximum set pressure F set And when the water pump stops working. According to the formulas (5) and (6), the water pump starts pressurizing from the beginning until the maximum set pressure f is reached set In the process of (1), normalized leakageThe variation of the leak amplitude with time can be expressed as:
Figure BDA0003798047660000061
it can be found that during the water pump start-up pressurization process (i.e. t < set -f 0 ) K), when there is no leakage, i.e. S =0, the leakage sound amplitude will not change over time; however, when there is a leak, i.e., S ≠ 0, the leak sound amplitude will vary over time.
In order to further analyze the characteristics of the leakage sound amplitude signal in the process of starting and pressurizing the water pump, in this embodiment, the characteristics of the normalized leakage sound amplitude signal are simulated under different conditions. According to the equation (7), fig. 2 shows the time variation of a' under different leakage hole areas obtained by simulation. The areas S of the leakage holes in the simulation are respectively set to be 2mm 2 、4mm 2 、8mm 2 、14mm 2 And 18mm 2 . Other simulation parameters are as follows: minimum set pressure f 0 =0.3MPa; maximum set pressure f set =0.5MPa; and the pressure increment k =0.005MPa/s per unit time under the water pump pressurization condition. According to the simulation result, the following results can be obtained: at the moment when the water pump just starts to pressurize, A' is continuously increased along with the increase of S; in the process of pressurizing the water pump, A' is continuously increased along with time to present a characteristic similar to a ramp signal, and the slope of the ramp signal is continuously increased along with the increase of S; when the water pressure reaches the maximum set pressure f set Then, A 'will remain constant, and the constant A' will increase with increasing S.
Let A 'be a normalized leakage sound amplitude signal at the time of pressurization upon start-up of the water pump' 0 And the amplitude signal corresponds to the minimum set pressure f 0 (ii) a Let A 'be the normalized leakage sound amplitude signal immediately after the water pump stops pressurizing' set And the amplitude signal corresponds to the maximum set pressure f set (ii) a Let Δ f set ＝f set -f 0 Is the difference between the set maximum water pressure and the set minimum water pressure. According to the equation (7), the variation of the normalized leakage sound amplitude signal before and after the pressurization of the water pump can be calculatedExpressed as:
ΔA'＝A' set -A' 0 ＝[(f 0 +Δf set ) 1.6 -f 0 1.6 ]S 0.5 (8)
FIG. 3 shows the difference Δ f obtained by simulation according to equation (8) set Under the condition, the change relation of delta A' and S is shown. Delta f in simulation set Respectively at 0.2MPa, 0.3MPa, 0.4MPa, 0.5MPa and 0.6MPa; f. of 0 Is 0.3MPa. It can be found that when S =0, i.e. no leakage occurs, Δ a' is 0; when S ≠ 0, i.e. a leak occurs, Δ A' follows S and Δ f set Is increasing.
Based on the theoretical analysis result of the amplitude signal characteristic, the invention provides a method for realizing the enhancement of the leakage signal of the water pipeline by detecting the delta A'.
Step 1: collecting vibration signals of a water pipeline before and after pressurization of a water pump;
step 2: calculating the amplitude of a vibration signal of a water pipe before and after the water pump is pressurized, and taking the amplitude difference of the vibration signal as a leakage signal to be detected;
and 3, comparing the leakage signal to be detected with a first threshold value, if the leakage signal is greater than the first threshold value, the water pipeline leaks, otherwise, the water pipeline is normal.
In order to verify the effect of enhancing the leakage signal of the water pipe, the present embodiment is a test study on the existing method for monitoring the leakage by monitoring the amplitude change of the vibration signal under constant water pressure (Lin Tianxiang, feng Shaokong, leaf crown forest, etc.. Method for monitoring the leakage of the large-scale pressure water pipe [ J]Vibration and shock, 2021, 40 (5): 136-142.) in comparison with the method proposed by the present invention. Let f n ＝(f 0 +f set ) 2 is an intermediate value between the minimum and maximum set pressures, and is assumed to be f at a constant water pressure n The amplitude of the vibration signal is monitored. FIG. 4 shows the difference Δ f obtained by simulation according to equation (5) set The relationship between the leakage acoustic amplitude a' and the leakage hole area S is normalized under the conditions. The simulation parameters are as above. It can be found that when S =0, the case where no leakage occursUnder the condition, A' is 0; when S ≠ 0, i.e. leakage occurs, A' will follow S and Δ f set Is increasing.
Comparing the simulation results of fig. 3 and fig. 4, it can be found that when Δ f set The signal delta A 'is larger than the signal A' under the condition of a certain value and the same leakage hole area. For example, when Δ f set When =0.6MPa, the leak hole area S is also 16mm 2 Under the condition of (1), delta A' is about 11.1X 10 6 And A' is only about 7.0X 10 6 . Therefore, the method proposed by the present invention is to select Δ f appropriately set A stronger leakage signal can be obtained, which contributes to an increase in detection sensitivity. On the other hand, the existing method adopting constant water pressure monitoring needs the water pump to work uninterruptedly according to the feedback signal of the water pressure sensor, which is easy to cause the damage of the water pump; the method provided by the invention only needs to start the water pump when the water pressure is reduced to the preset minimum value, so that the probability of fatigue damage caused by long-term uninterrupted work of the water pump is reduced.
In this example, for further discussion of Δ f set Regarding the influence of the signal enhancement degree of Δ a 'relative to a', the signal amplification factor can be expressed by the following expressions (5) and (8):
Figure BDA0003798047660000071
FIG. 5 shows the difference f obtained by simulation according to equation (9) 0 Time r and Δ f set The relationship between them. In simulation, f 0 Respectively taking 0.2MPa, 0.3MPa, 0.4MPa, 0.5MPa and 0.6MPa. It can be found that at a certain f 0 Under the condition that r is dependent on delta f set Is continuously increased and continuously approaches to 3; Δ f to make r greater than 1 set Needs to be greater than a certain value, and the value follows f 0 Is increased, e.g. when f is increased 0 At 0.2MPa and 0.6MPa, Δ f set Greater than about 0.19MPa and 0.55MPa, respectively, are required to satisfy r greater than 1. Therefore, in a practical system, f can be optimized 0 And Δ f set To realize the increase of the monitoring signalCompared with the existing method for monitoring leakage by monitoring the change of the amplitude of the vibration signal under constant water pressure, the method provided by the invention can amplify the signal to be nearly 3 times, thereby improving the signal-to-noise ratio of the monitoring signal.
Based on the method for enhancing the leakage signal of the water pipeline, the invention provides a system for monitoring the leakage signal of the tunnel fire-fighting water pipeline, which is used for monitoring the leakage condition of the water pipeline. As shown in fig. 6, the system includes a state triggering module, an amplitude detection module, and a leak determination module. The system can realize the judgment of leakage aiming at the vibration signals of certain 1 vibration sensor. According to the system shown in fig. 1, each section of water pipe corresponds to 1 vibration sensor, so that the output vibration signal of each sensor is obtained through the amplitude detection module, distributed monitoring of the tunnel fire-fighting water pipe can be realized, and the section of water pipe where the leakage point is located is determined.
The state trigger module is used for sending a working state instruction of the water pump. The working state of the water pump is divided into preparation before starting, starting pressurization and ending pressurization.
In the embodiment, when the water pump just starts to enter a preparation state before starting, the state trigger module sends a starting pressurization preparation instruction 1 to the amplitude detection module and the leakage judgment module; when the water pump just enters a starting pressurization state, the state trigger module sends a starting pressurization instruction 2 to the amplitude detection module and the leakage judgment module; when the water pump just enters the pressurizing ending state, the state triggering module sends a pressurizing ending command 3 to the amplitude detection module and the leakage judgment module. Here, the time interval between the transmission of instruction 1 and instruction 2 is set to t p 。
The amplitude detection module is used for sampling a vibration signal of the vibration sensor and processing data by combining an instruction sent by the state trigger module.
In this embodiment, when the amplitude detection module receives the instruction 1 sent by the state trigger module, the amplitude detection module starts to sample the vibration signal of the vibration sensor with Δ T as a time interval, and with T as an amplitude extraction period. In each amplitude extraction period T, the maximum value and the minimum value of the sampled vibration signal are obtained by a comparison method, the minimum value is subtracted from the maximum value, so that the amplitude of each period T is obtained, and the amplitude of each period T is stored.
When the time t elapses p When receiving the instruction 2 sent by the state trigger module, the amplitude detection module stops sampling the vibration signal and calculating the amplitude of each period T, and the calculation is changed to T p Amplitude average A stored in time period v1 And sends the value to the leak determination module.
When receiving an instruction 3 sent by the state trigger module, the amplitude detection module restarts sampling the vibration signal of the vibration sensor at a time interval of Δ t, and calculates and stores amplitude data (such as the process when receiving the instruction 1); when the time t elapses p Thereafter, the stored amplitude average A is calculated v2 And sends the value to the leak determination module.
The leakage determination module is used for determining a leakage state.
In this embodiment, when the leakage determination module receives the instruction 1 sent by the state trigger module, the leakage determination module enters a preparation state, and clears the relevant register. When receiving the first amplitude average value A sent by the amplitude detection module v1 This value is then stored in register R1; when receiving the second amplitude average value A sent by the amplitude detection module v2 This value is then stored in register R2. Finally calculating to obtain A v1 And A v2 The difference is compared with a decision threshold A th A comparison is made. When the difference between the two averages is greater than or equal to A th If so, determining leakage; when the difference between the two averages is less than A th If so, the system is judged to be normal.
In order to verify the effect of the monitoring system, the present embodiment is verified by numerical simulation. In an actual tunnel fire-fighting water pipeline system, background noise exists in a vibration signal, and for convenience of analysis, the background noise is assumed to be a normally distributed random signal. In the simulation, the time when the water pump enters the preparation state just before starting is taken as 0 time, so the normalized vibration signal can be expressed as:
Figure BDA0003798047660000091
in the formula: v (t) is a normal distribution random signal with the mean value of 1 and the standard deviation of 1; and B is the normalized amplitude of the background noise of the vibration signal.
Fig. 7 is a normalized vibration signal for different leak hole areas obtained by simulation according to equation (10). In FIGS. 7 (a) to (b), the leak hole areas S are respectively 18mm 2 、14mm 2 、8mm 2 、5mm 2 、4mm 2 、2mm 2 、1mm 2 And a vibration signal at 0. The simulation parameters are as follows: f. of 0 ＝0.3MPa；f set ＝0.5MPa；k＝0.005MPa/s，t p ＝10s，B＝3×10 6 . In the figure, the water pump is in a preparation state before starting in the time range of 0-10 s; in the time range of 10s-50s, the water pump is in a starting pressurization state; and in the time range of 50s-60s, the water pump is in a pressurizing ending state. It can be seen that the amplitude of the vibration signal generally decreases continuously with decreasing S; during the process of starting pressurization of the water pump, the amplitude of the vibration signal has an increasing change process, and the process becomes less obvious along with the reduction of S.
The vibration signal of fig. 7 was subjected to state determination by the above system, and the results shown in table 1 were obtained. The simulation parameters are as follows: Δ t =1ms; t =100ms; a. The th ＝3×10 6 . It can be found that when S is greater than or equal to 4mm 2 And under the condition of no leakage, a correct judgment result can be obtained; however, when S =2mm 2 And 1mm 2 In time, an erroneous determination result occurs. This is mainly because when the leak hole area is reduced to a certain extent, the change amount of the obtained amplitude before and after the pressurization of the water pump becomes smaller than the determination threshold a th Thereby misjudging the leakage as normal.
TABLE 1 determination results (A) th ＝3×10 6 )
Figure BDA0003798047660000101
In order to improve the accuracy of the leakage judgment, A is used in the simulation model th Reduced to 1.5 × 10 6 The results of determination shown in Table 2 were obtained. It can be found that the determination results are all correct. Thus, reduce A th The determination accuracy in the leak state is improved.
TABLE 2 determination results (A) th ＝1.5×10 6 )
Figure BDA0003798047660000102
Based on the above analysis results, the present embodiment further sets the threshold value A th Reduced to 1.5 × 10 5 The results of determination shown in Table 3 were obtained.
TABLE 3 determination results (A) th ＝1.5×10 5 )
Figure BDA0003798047660000111
Unlike the results in table 2, table 3 shows that the correct determination result can be obtained even in the case of a leak, but there is a certain probability of erroneous determination in the case of no leak. This is mainly because the change amount of the amplitude before and after the pressurization of the water pump is made to match the determination threshold a due to the presence of random noise in the case of no leakage th Has uncertainty about the magnitude relationship of (a).
Based on the above analysis results, A th The leakage judgment of a small-area leakage hole can be caused if the size of the leakage hole is too large; and A is th Too small may cause erroneous determination of a no-leak condition. Therefore, in the system, it is necessary to set A reasonably according to the actual situation th To improve the accuracy of the determination.
In one embodiment of the present invention, the leakage determination module may further implement a multi-level determination of the leakage area, and the leakage determination module sets the leakage classification determination threshold B th 。
In the present embodiment, the leak detection modeWhen the block receives an instruction 1 sent by the state trigger module, the leakage judgment module enters a preparation state and clears the relevant register. When receiving the first amplitude average value A sent by the amplitude detection module v1 This value is then stored in register R1; when receiving the second amplitude average value A sent by the amplitude detection module v2 This value is then stored in register R2. Finally calculating to obtain A v1 And A v2 A difference between the first and second thresholds, and a determination threshold A th A comparison is made. When the difference between the two averages is less than A th If so, the system is judged to be normal. When the difference between the two averages is greater than or equal to A th Then, further compare with the decision threshold B th A comparison is made. When the difference between the two average values is less than B th If so, judging the leakage to be small; when the difference between the two averages is greater than or equal to B th If so, it is determined as a large leak.
The leakage judgment module with the multi-stage judgment function is adopted to construct a simulation model, normalized vibration signals under different leakage hole areas shown in the figure 7 are adopted, and the leakage hole areas S are respectively 18mm 2 、14mm 2 、8mm 2 、5mm 2 、4mm 2 、2mm 2 、1mm 2 And 0. The simulation parameters are as follows: f. of 0 ＝0.3MPa；f set ＝0.5MPa；k＝0.005MPa/s，t p ＝10s，B＝3×10 6 ；△t＝1ms；T＝100ms；A th ＝1.5×10 6 ；B th ＝3×10 6 . The simulation results are shown in table 4.
TABLE 4 results of the ranking determination (A) th ＝1.5×10 6 ,B th ＝3×10 6 )
Figure BDA0003798047660000121
According to the simulation result, when S is more than or equal to 4mm 2 If (3), it is determined to be a large leak; when S is 2mm 2 And 1mm 2 And when the leakage is small, the small leakage is judged, and the classified monitoring of the health state is realized.
The foregoing lists merely illustrate specific embodiments of the invention. It is obvious that the invention is not limited to the above embodiments, but that many variations are possible. All modifications which can be derived or suggested by a person skilled in the art from the disclosure of the present invention are to be considered within the scope of the invention.

Claims (7)

1. A method for enhancing a leakage signal of a tunnel fire-fighting water pipeline is characterized by comprising the following steps:
step 1: collecting vibration signals of a water pipeline before and after pressurization of a water pump;
step 2: calculating the amplitude of the vibration signal of the water pipeline before and after the water pump is pressurized, and taking the amplitude difference of the vibration signal as a leakage signal to be detected;
and 3, comparing the leakage signal to be detected with a first threshold value, if the leakage signal is greater than the first threshold value, leaking the water pipeline, otherwise, the water pipeline is normal.
2. The method for enhancing the leakage signal of the tunnel fire-fighting water pipe according to claim 1, wherein in the step 3, if the leakage signal is greater than a first threshold value, the leakage signal to be detected is continuously compared with a second threshold value, if the leakage signal is greater than the second threshold value, the large leakage occurs in the water pipe, otherwise, the small leakage occurs in the water pipe.
3. The method for enhancing the leakage signal of the tunnel fire fighting water pipe according to claim 1, wherein the amplification rate of the leakage signal is optimized by adjusting the minimum set pressure and the maximum set pressure of a water pump; the amplification ratio of the leakage signal is as follows:
Figure FDA0003798047650000011
wherein f is 0 Indicating the minimum set pressure, f set Indicating the maximum set pressure and r the leak signal amplification.
4. A tunnel fire-fighting water pipe leakage signal monitoring system is characterized in that the tunnel fire-fighting water pipe is divided into a plurality of areas, and each area is provided with a vibration sensor; a water pump is installed at one end of the tunnel fire-fighting water pipeline, and a pressure sensor is installed at the outlet section water pipe of the water pump;
the monitoring system comprises:
the state trigger module is used for sending a working state instruction of the water pump, and the working state of the water pump comprises preparation before starting, pressurization starting and pressurization ending and corresponds to an instruction 1, an instruction 2 and an instruction 3 respectively;
the amplitude detection module is used for sampling a vibration signal of the vibration sensor, performing data processing by combining an instruction sent by the state trigger module, and calculating an amplitude average value of the vibration signal of the water pipeline before and after the water pump is pressurized;
and the leakage judging module is used for receiving the amplitude average value of the vibration signals of the water pipeline before and after the water pump is pressurized, which is sent by the amplitude detecting module, taking the amplitude difference as a leakage signal to be detected, comparing the amplitude difference with a first threshold value, if the leakage signal is greater than the first threshold value, the water pipeline leaks, and otherwise, the water pipeline is normal.
5. The system for monitoring the leakage signal of the tunnel fire-fighting water pipe according to claim 4, wherein the working procedures of the state triggering module for sending the working state instruction are as follows:
when the water pump just starts to enter a preparation state before starting, the state trigger module sends a starting pressurization preparation instruction 1 to the amplitude detection module and the leakage judgment module; when the water pump just enters a starting pressurization state, the state trigger module sends a starting pressurization instruction 2 to the amplitude detection module and the leakage judgment module; when the water pump just enters the pressurizing ending state, the state triggering module sends a pressurizing ending command 3 to the amplitude detection module and the leakage judgment module.
6. The system for monitoring the leakage signal of the tunnel fire fighting water pipe according to claim 5, wherein when the amplitude detection module receives the instruction 1 sent by the state trigger module, the amplitude detection module starts to sample the vibration signal of the vibration sensor with Δ T as a time interval and with T as an amplitude extraction period; in each amplitude extraction period T, obtaining the maximum value and the minimum value of the sampled vibration signals by adopting a comparison method, subtracting the minimum value from the maximum value to obtain the amplitude of each period T, and storing the amplitude of each period T;
when the amplitude detection module receives the instruction 2 sent by the state trigger module, the amplitude detection module stops sampling the vibration signal and calculating the amplitude of each period T, and calculates the amplitude at T p Amplitude average A stored in time period v1 And sending the value to a leakage determination module; wherein, t p Represents the time interval of instruction 1 and instruction 2;
when the amplitude detection module receives an instruction 3 sent by the state trigger module, the amplitude detection module restarts sampling a vibration signal of the vibration sensor by taking delta T as a time interval, and taking T as an amplitude extraction period; in each amplitude extraction period T, obtaining the maximum value and the minimum value of the vibration signal obtained by sampling by adopting a comparison method, subtracting the minimum value from the maximum value to obtain the amplitude of each period T, and storing the amplitude of each period T; when the time t elapses p Thereafter, the stored amplitude average A is calculated v2 And sends the value to the leak determination module.
7. The tunnel fire fighting water pipe leakage signal monitoring system according to claim 4, wherein a second threshold is further set in the leakage determination module, if the leakage signal is greater than the first threshold, the leakage signal to be detected is continuously compared with the second threshold, if the leakage signal is greater than the second threshold, the water pipe is leaked largely, and otherwise, the water pipe is leaked sparingly.
CN202210975913.XA 2022-08-15 2022-08-15 Tunnel fire-fighting water pipeline leakage signal enhancement method and monitoring system Pending CN115405867A (en)

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