Tunnel fire water delivery conduit leak signal enhancement method and monitoring system

Abstract

The application discloses a tunnel fire-fighting water conveying pipeline leakage signal enhancement method and a monitoring system, and belongs to the field of water conveying pipeline detection. Firstly, vibration signals of the water conveying pipeline before and after water pump pressurization are collected; then amplitudes of the vibration signals of the water conveying pipeline before and after water pump pressurization are calculated, and a vibration signal amplitude difference is taken as a leakage signal to be detected; finally, the leakage signal to be detected is compared with a first threshold value, if the leakage signal is greater than the first threshold value, the water conveying pipeline is in leakage, otherwise, the water conveying pipeline is normal. Research results show that compared with existing technologies using vibration signals under constant water pressure conditions, the method proposed by the application can increase the leakage signal intensity to nearly 3 times under certain conditions, and effectively improves the leakage detection sensitivity of the tunnel fire-fighting water conveying pipeline. Simulation analysis results show that reasonable selection of the vibration signal amplitude difference determination threshold value helps to reduce the leakage state misjudgment rate and the non-leakage state misjudgment rate.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of water pipeline detection, in particular to a tunnel fire-fighting water pipeline leakage signal enhancement method. BACKGROUND

[0002] With the rapid development of expressway tunnels, tunnel fire safety issues are gradually attracting widespread attention. Due to the relatively closed and narrow space of tunnels compared to other road sections, the entrances are few and far apart, so once a fire occurs in a tunnel, it will be difficult to avoid and rescue, and if not timely controlled, it will cause great economic losses and casualties. Ensuring the integrity of tunnel fire-fighting facilities is a prerequisite for timely and effective fire fighting after a fire occurs, and it is also a requirement of the management responsibilities of the management unit. Fire-fighting water pipelines are one of the important fire-fighting facilities in tunnels, and leakage of the water pipelines will pose a safety hazard to the tunnel.

[0003] Currently, the maintenance of fire-fighting facilities such as water pipelines in highway tunnels is mainly based on the "Highway Tunnel Maintenance Technical Specification" (JTG H12-2015) issued by the Ministry of Transport, which stipulates that water supply pipelines should be inspected once every 1 to 3 months to check for leaks. In practice, the leakage detection of water pipelines is usually done by manual visual inspection, which makes the water pipeline state information lag and the detection data difficult to trace, and at the same time, the passing vehicles in the tunnel also pose a certain risk to the safety of the maintenance personnel. Therefore, it is necessary to develop a non-manual, real-time water pipeline monitoring technology to solve the above problems.

[0004] Currently, domestic and foreign scholars have proposed a variety of monitoring technologies for water pipeline leakage. Lin Tianxiang et al. studied a technology for long-term continuous monitoring of leakage using the amplitude change of vibration signals caused by water pipeline leakage in 2021. This technology uses a hydrophone installed in the pipeline to obtain the vibration signals of the leakage source, which has certain advantages and feasibility in reducing the influence of environmental factors. However, during the use of this technology, the background noise of the vibration signals of the water pipeline itself in the non-leakage state can interfere with the detection of leakage: on the one hand, the amplitude change of the weak vibration signals caused by small leakage holes may be submerged in the background noise, resulting in missed detection of the leakage state; on the other hand, the amplitude of the background noise is often disturbed by various factors such as the environment, which not only may cause missed detection of the leakage state, but also may cause false judgment of the non-leakage state. In addition, this technology often needs to be implemented under constant water pressure, which often requires the water pump to work continuously for a long time, increasing the probability of water pump damage to some extent. SUMMARY

[0005] In order to solve the above technical problems, the application provides a tunnel fire-fighting water supply pipeline leakage signal enhancement method, which utilizes the water pressure difference of the water supply pipeline in two states of water pump starting pressurization beginning and ending, and realizes the judgment of the leakage by monitoring the change of the vibration signal amplitude difference in the two states. Since the application detects the vibration signal amplitude difference, the influence of the long-term fluctuation of the background noise amplitude on the detection result is reduced to a certain extent, and the strength of the leakage signal is increased by optimizing the water pressure difference, so that the signal-to-noise ratio of the detection signal is finally improved.

[0006] In order to achieve the above purpose, the application adopts the following technical scheme:

[0007] The first purpose of the application is to provide a tunnel fire-fighting water supply pipeline leakage signal enhancement method, which comprises the following steps:

[0008] Step 1: collecting the vibration signals of the water supply pipeline before and after the water pump pressurization;

[0009] Step 2: calculating the amplitudes of the vibration signals of the water supply pipeline before and after the water pump pressurization, and taking the vibration signal amplitude difference as the leakage signal to be detected;

[0010] Step 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 supply pipeline leaks, otherwise the water supply pipeline is normal.

[0011] Further, in step 3, if the leakage signal is greater than the first threshold value, the leakage signal to be detected is further compared with a second threshold value, if the leakage signal is greater than the second threshold value, the water supply pipeline has a large leakage, otherwise the water supply pipeline has a small leakage.

[0012] 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 rate of the leakage signal is:

[0013]

[0014] Wherein, f0 represents the minimum set pressure, f set represents the maximum set pressure, and r represents the amplification rate of the leakage signal.

[0015] The second purpose of the application is to provide a tunnel fire-fighting water supply pipeline leakage signal monitoring system, the tunnel fire-fighting water supply pipeline is divided into several regions, and a vibration sensor is installed in each region; one end of the tunnel fire-fighting water supply pipeline is provided with a water pump, and a pressure sensor is installed at the outlet section of the water pump; the monitoring system comprises:

[0016] A state triggering module is configured to send a working state instruction of the water pump, wherein the working state of the water pump includes a pre-start preparation state, a start pressurization state and an end pressurization state, which correspond to instruction 1, instruction 2 and instruction 3 respectively;

[0017] An amplitude detection module is configured to sample the vibration signal of the vibration sensor and perform data processing in combination with the instruction sent by the state triggering module, and calculate the amplitude average value of the vibration signal of the water delivery pipeline before and after pressurization of the water pump;

[0018] A leakage judgment module is configured to receive the amplitude average value of the vibration signal of the water delivery pipeline before and after pressurization of the water pump sent by the amplitude detection module, take the amplitude difference as a leakage signal to be detected, and compare the leakage signal with a first threshold value, wherein if the leakage signal is greater than the first threshold value, the water delivery pipeline is in leakage, otherwise, the water delivery pipeline is normal.

[0019] Further, the state triggering module sends the working state instruction in the following procedure:

[0020] When the water pump just enters the pre-start preparation state, the state triggering module sends the start pressurization preparation instruction 1 to the amplitude detection module and the leakage judgment module; when the water pump just enters the start pressurization state, the state triggering module sends the start pressurization instruction 2 to the amplitude detection module and the leakage judgment module; when the water pump just enters the end pressurization state, the state triggering module sends the end pressurization instruction 3 to the amplitude detection module and the leakage judgment module.

[0021] Further, when the amplitude detection module receives the instruction 1 sent by the state triggering module, the amplitude detection module starts sampling the vibration signal of the vibration sensor with △t as the time interval and 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 using a comparison method, and the maximum value is subtracted from the minimum value, so as to obtain the amplitude of each period T, and the amplitudes of the periods T are stored;

[0022] When the amplitude detection module receives the instruction 2 sent by the state triggering module, the amplitude detection module stops sampling the vibration signal and calculating the amplitude of each period T, and calculates the amplitude average value A of the stored amplitudes in the time period of t p v1 , and sends the value to the leakage judgment module; wherein, t p represents the time interval of the instruction 1 and the instruction 2;

[0023] ​When the amplitude detection module receives the instruction 3 sent by the state triggering module, the amplitude detection module restarts sampling the vibration signal of the vibration sensor with △t as a time interval and 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 using the comparison method, and the maximum value is subtracted from the minimum value, so as to obtain the amplitude of each period T, and the amplitudes of the periods T are stored; when the time t p passes, the average value A v2 of the stored amplitudes is calculated, and the value is sent to the leakage judgment module.

[0024] Further, the second threshold value is also set in the leakage judgment module, if the leakage signal is greater than the first threshold value, the leakage signal to be detected is compared with the second threshold value, if the leakage signal is greater than the second threshold value, the water supply pipeline has a large leakage, otherwise the water supply pipeline has a small leakage.

[0025] Compared with the prior art, the advantages of the present application are that:

[0026] Based on the characteristics of the vibration signal of the water supply pipeline during the water pump starting and pressurizing process, the present application proposes to use the amplitude difference of the vibration signal before and after the water pump pressurizing to enhance the leakage signal of the tunnel fire-fighting water supply pipeline, and further realizes the monitoring of the leakage of the water supply pipeline, and improves the signal-to-noise ratio of the useful signal. The research results show that, compared with the existing technology of using the vibration signal under the condition of constant water pressure, the method proposed in the present application can increase the leakage signal intensity to nearly 3 times under certain conditions, effectively improving the leakage detection sensitivity of the tunnel fire-fighting water supply pipeline. The simulation analysis results show that the reasonable selection of the vibration signal amplitude difference judgment threshold value helps to reduce the leakage rate of the leakage state and the false judgment rate of the non-leakage state. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 is the basic block diagram of the tunnel fire-fighting water supply pipeline system shown in the embodiment of the present application;

[0028] Figure 2 is the change relationship between the normalized leakage sound amplitude A' and the time t under different leakage hole areas S during the water pump starting and pressurizing process obtained by simulation;

[0029] Figure 3 is the relationship between the change amount △A' of the normalized leakage sound amplitude signal before and after the water pump pressurizing and the leakage hole area S under different water pressure differences △f set ;

[0030] Figure 4 is the relationship between the change amount △A' of the normalized leakage sound amplitude signal before and after the water pump pressurizing and the leakage hole area S under different water pressure differences △f setThe relationship between the normalized leakage sound amplitude A' and the leakage hole area S under the condition;

[0031] Figure 5 The relationship between the signal amplification rate r and the water pressure difference △f under the condition of different minimum set pressures f0 is obtained through simulation. set

[0032] Figure 6 Fig. 1 is a schematic diagram of a tunnel fire-fighting water pipeline leakage signal monitoring system according to an embodiment of the present application;

[0033] Figure 7 The normalized vibration signal under different leakage hole areas is obtained through simulation. DETAILED DESCRIPTION

[0034] The present application will be further described below with reference to the accompanying drawings.

[0035] In this embodiment, the basic principle of the present application is explained through theoretical derivation, the characteristics of the technology are analyzed through numerical simulation, a tunnel fire-fighting water pipeline leakage signal enhancement method and monitoring system are proposed according to the characteristics of the technology, and finally the implementation effect of the present application is demonstrated through numerical simulation.

[0036] Figure 1 Fig. 1 is a basic block diagram of a tunnel fire-fighting water pipeline system. The system mainly consists of a water pipeline, a fire hydrant and a water pump.

[0037] The water pipeline in the tunnel is installed with a fire hydrant every certain length, so as to divide the entire tunnel water pipeline into multiple equal-length regions. In order to monitor the vibration signal of the water pipeline, a vibration sensor is installed at the water pipeline near each fire hydrant, so that each section of the water pipeline corresponds to a vibration sensor, thereby realizing distributed monitoring of the vibration signal of the segmented region of the water pipeline.

[0038] The water pump is used to provide the required water pressure for the water pipeline. In order to obtain the water pressure in the water pipeline in real time, a pressure sensor is installed at the water pipeline at the outlet section of the water pump. In the actual working process of the water pump, the control system pre-sets the maximum and minimum values of the water pressure. When the water pressure monitored by the pressure sensor is lower than the pre-set minimum value, the water pump starts to supply water and pressurize until the water pressure monitored by the pressure sensor reaches the pre-set maximum value, and the water pump stops supplying water and pressurizing. The entire tunnel fire-fighting water pipeline system is just ensured to meet the requirements of water pressure through the above method.

[0039] If the water pipeline leaks, the leakage sound power can be expressed as:

[0040]

[0041] ​where v is the water flow leakage velocity; p is the water flow density at the leakage hole; p0 is the initial water flow density; C0 is the sound speed at the location of the tunnel; 1 is the size of the leakage hole; K is a proportional coefficient; and n is a constant between 6 and 8. Assuming that the water flow density is constant, i.e., p0 = p, and the sound speed at the location of the tunnel is constant, the leakage sound power can be expressed as:

[0042] P W = λv n S (2)

[0043] where λ is a constant; and S is the area of the leakage hole. According to the Bernoulli equation, assuming that the leakage of the fire water supply pipeline is a small hole leakage problem, the leakage sound amplitude can be approximately expressed as:

[0044]

[0045] where μ is a constant; and F is the operating pressure of the water supply pipeline. In this embodiment, n is set to 6.4, and the leakage sound amplitude can be obtained as:

[0046]

[0047] In order to simplify the analysis, the normalized leakage sound amplitude is expressed as:

[0048]

[0049] In an actual system, when the pressure sensor detects that the operating pressure F of the water supply pipeline is less than the minimum set pressure f0, the water pump is started and begins to pressurize the water supply pipeline. In order to facilitate analysis, it is assumed that the initial pressure of the water pump when it is started is f0, and the pressure increases linearly with time t after the water pump is started, and thus the operating pressure of the water supply pipeline after the water pump is started can be expressed as:

[0050] F(t) = f0 + kt (6)

[0051] where k is the pressure increase coefficient of the water supply pipeline per unit time under the water pump pressurization condition. Here, it is assumed that when F reaches the maximum set pressure f set , the water pump stops working. According to equations (5) and (6), during the process from when the water pump is started to pressurize until the maximum set pressure f set is reached, the normalized leakage sound amplitude changes with time and can be expressed as:

[0052]

[0053] It can be found that, during the process of water pump pressurization (i.e., t set - f0) / k), when there is no leakage, i.e., S = 0, the leakage sound amplitude will not change with time; however, when there is leakage, i.e., S ≠ 0, the leakage sound amplitude will change with time.

[0054] In order to further analyze the characteristics of the leakage sound amplitude signal in the water pump starting pressurization process, in this embodiment, the normalized leakage sound amplitude signal characteristics are simulated under different conditions. According to formula (7), Figure 2 is the change relationship of A' with time under different leakage hole areas obtained by simulation. In the simulation, the leakage hole area S is respectively set to 2mm 2 , 4mm 2 , 8mm 2 , 14mm 2 and 18mm 2 . Other simulation parameters are as follows: minimum set pressure f0=0.3MPa; maximum set pressure f set =0.5MPa; pressure increment per unit time under water pump pressurization k=0.005MPa / s. According to the simulation results, it can be obtained that at the moment when the water pump starts to pressurize, A' increases continuously with the increase of S; during the water pump pressurization process, A' will increase continuously with time, showing a characteristic of an approximate ramp signal, and the slope of the ramp signal increases continuously with the increase of S; after the water pressure reaches the maximum set pressure f set , A' will remain constant, and the constant A' increases continuously with the increase of S.

[0055] Assume that the normalized leakage sound amplitude signal when the water pump starts to pressurize is A'0, and the amplitude signal corresponds to the minimum set pressure f0; assume that the normalized leakage sound amplitude signal when the water pump stops pressurizing is A' set , and the amplitude signal corresponds to the maximum set pressure f set ; assume that△f set =f set -f0 is the difference between the set maximum water pressure and the minimum water pressure. According to formula (7), the change of the normalized leakage sound amplitude signal before and after the water pump pressurization can be represented as:

[0056] ΔA'=A' set -A'0=[(f0+Δf set ) 1.6 -f0 1.6 ]S 0.5 (8)

[0057] According to formula (8), Figure 3 is the change relationship of△A' with S under different△f set obtained by simulation. In the simulation,△f set is respectively 0.2MPa, 0.3MPa, 0.4MPa, 0.5MPa and 0.6MPa; f0 is 0.3MPa. It can be found that when S=0, i.e. no leakage occurs,△A' is 0; when S≠0, i.e. leakage occurs,△A' will increase with S and△f setIt continues to increase as it grows.

[0058] Based on the theoretical analysis of the amplitude signal characteristics described above, this invention proposes a method for enhancing leakage signals in water pipelines by detecting ΔA'.

[0059] Step 1: Collect vibration signals of the water pipeline before and after the water pump pressurizes the water;

[0060] Step 2: Calculate the amplitude of the vibration signal of the water pipeline before and after the water pump pressurizes the water, and take the difference in vibration signal amplitude as the leakage signal to be detected;

[0061] Step 3: Compare the leak signal to be detected with the first threshold. If the leak signal is greater than the first threshold, the water pipeline is leaking; otherwise, the water pipeline is normal.

[0062] To verify the enhanced signal enhancement effect of the water pipeline leakage detection method of the present invention, this embodiment compares the existing method of detecting leakage by monitoring the change in vibration signal amplitude under constant water pressure (Lin Tianxiang, Feng Shaokong, Ye Guanlin, et al. Experimental study on leakage detection method of large pressure water pipeline [J]. Vibration and Shock, 2021, 40(5): 136-142.) with the method proposed in this invention. n =(f0+f set ) / 2 is the median value between the minimum and maximum set pressures, assuming a constant water pressure of f. n The vibration signal amplitude is monitored under the condition of (5). Figure 4 Different Δf obtained through simulation set The relationship between the normalized leakage sound amplitude A' and the leakage orifice area S under the given conditions is shown. Simulation parameters are the same as above. It can be observed that when S = 0, i.e., no leakage occurs, A' is 0; when S ≠ 0, i.e., leakage occurs, A' will vary with S and Δf. set It continues to increase as it grows.

[0063] contrast Figure 3 and Figure 4 Simulation results show that when Δf set Under certain conditions, for the same leak hole area, the ΔA' signal will be greater than the A' signal. For example, when Δf set When the pressure is 0.6 MPa, the leakage hole area S is still 16 mm². 2 Under these conditions, △A' is approximately 11.1 × 10⁻⁶. 6 A' is only about 7.0 × 10⁻⁶. 6 Therefore, the method proposed in this invention achieves its effect by appropriately selecting Δf. setThe stronger leakage signal can be obtained, which helps to improve the detection sensitivity. On the other hand, the existing method of monitoring under constant water pressure requires the water pump to work uninterruptedly according to the feedback signal of the water pressure sensor, which is easy to cause damage to the water pump; and the method provided by the application only needs to start the water pump when the water pressure drops to the preset minimum value, thereby reducing the probability of fatigue damage caused by long-term uninterrupted work of the water pump.

[0064] In this embodiment, in order to further discuss △f set According to formulas (5) and (8), the expression of the signal amplification rate is obtained as follows:

[0065]

[0066] According to formula (9), Figure 5 The relationship between r and △f set under different f0 is obtained through simulation. In the simulation, f0 is 0.2 MPa, 0.3 MPa, 0.4 MPa, 0.5 MPa and 0.6 MPa respectively. It can be found that under certain f0, r increases with the increase of △f set , and constantly approaches 3; in order to make r greater than 1, △f set needs to be greater than a certain value, and the value increases with the increase of f0, for example, when f0 is 0.2 MPa and 0.6 MPa, △f set needs to be greater than about 0.19 MPa and 0.55 MPa respectively to meet the condition that r is greater than 1. Therefore, in the actual system, the enhancement of the monitoring signal can be realized by optimizing f0 and △f set The method proposed in the application can amplify the signal to nearly 3 times compared with the existing method of monitoring the change of the vibration signal amplitude under constant water pressure to realize leakage monitoring, thereby improving the signal-to-noise ratio of the monitoring signal.

[0067] Based on the above method of enhancing the leakage signal of the water conveying pipeline, the application provides a tunnel fire-fighting water conveying pipeline leakage signal monitoring system for monitoring the leakage of the water conveying pipeline. As shown in Figure 6 The system includes a state triggering module, an amplitude detection module and a leakage determination module. The system can determine the leakage according to the vibration signal of a vibration sensor. According to the system shown in Figure 1 Since each section of the water conveying pipeline corresponds to one vibration sensor, the distributed monitoring of the tunnel fire-fighting water conveying pipeline can be realized by acquiring the output vibration signal of each sensor through the amplitude detection module, so as to determine which section of the water conveying pipeline the leakage point is located in.

[0068] The state triggering module is configured to send a working state instruction of the water pump. The working state of the water pump includes a pre-start preparation state, a start pressurization state and an end pressurization state.

[0069] In the embodiment, when the water pump just enters the pre-start preparation state, the state triggering module sends a start pressurization preparation instruction 1 to the amplitude detection module and the leakage determination module; when the water pump just enters the start pressurization state, the state triggering module sends a start pressurization instruction 2 to the amplitude detection module and the leakage determination module; and when the water pump just enters the end pressurization state, the state triggering module sends an end pressurization instruction 3 to the amplitude detection module and the leakage determination module. The time interval between the instruction 1 and the instruction 2 is set as t p .

[0070] The amplitude detection module is configured to sample the vibration signal of the vibration sensor and perform data processing in combination with the instruction sent by the state triggering module.

[0071] In the embodiment, when the amplitude detection module receives the instruction 1 sent by the state triggering module, the amplitude detection module starts to sample the vibration signal of the vibration sensor with △t as the time interval and 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 using a comparison method, and the maximum value is subtracted from the minimum value, so as to obtain the amplitude of each period T, and the amplitudes of the periods T are stored.

[0072] When the time t p passes, the amplitude detection module receives the instruction 2 sent by the state triggering module, stops sampling the vibration signal and calculating the amplitude of each period T, and starts to calculate the average amplitude A p stored in the time period t v1 , and sends the value to the leakage determination module.

[0073] When the instruction 3 sent by the state triggering module is received, the amplitude detection module starts to sample the vibration signal of the vibration sensor again with △t as the time interval, and calculates and stores the amplitude data (as the process when the instruction 1 is received); after the time t p passes, the average amplitude A v2 stored is calculated, and the value is sent to the leakage determination module.

[0074] The leakage determination module is configured to determine the leakage state.

[0075] In the embodiment, when the leakage determination module receives the instruction 1 sent by the state triggering module, the leakage determination module enters a preparation state and clears the related registers. When the first average amplitude A v1Then, the value is stored in register R1; when the second amplitude average value A is received from the amplitude detection module... v2 Then, the value is stored in register R2. Finally, A is calculated. v1 With A v2 The difference, and the judgment threshold A th Compare them. When the difference between the two means is greater than or equal to A... th When the difference between the two average values ​​is less than A, it is determined to be a leak; th When the time is right, it is considered normal.

[0076] To verify the effectiveness of the monitoring system described above, this embodiment uses numerical simulation. In actual tunnel fire-fighting water supply pipeline systems, the vibration signal will contain background noise. For ease of analysis, it is assumed that the background noise is a normally distributed random signal. In the simulation, the moment when the water pump just enters the pre-start preparation state is taken as time 0. Therefore, the normalized vibration signal can be expressed as:

[0077]

[0078] In the formula: v(t) is a normally distributed random signal with a mean of 1 and a standard deviation of 1; B is the normalized amplitude of the background noise of the vibration signal.

[0079] According to equation (10), Figure 7 These are normalized vibration signals obtained through simulation for different leakage orifice areas. Figure 7 (a) to (b) represent the leakage hole area S, respectively, with each area set to 18 mm. 2 14mm 2 8mm 2 5mm 2 4mm 2 2mm 2 1mm 2 The vibration signal at 0. The simulation parameters are as follows: f0 = 0.3 MPa; f set =0.5MPa; k=0.005MPa / s, t p =10s, B=3×10 6 In the figure, within the time range of 0-10s, the water pump is in the pre-start preparation state; within the time range of 10s-50s, the water pump is in the start-up pressurization state; and within the time range of 50s-60s, the water pump is in the end-pressurization state. It can be observed that the vibration signal amplitude generally decreases as S decreases; however, during the start-up pressurization process, the vibration signal amplitude exhibits a continuous increasing variation, and this process becomes less pronounced as S decreases.

[0080] Through the above system Figure 7The vibration signals of the water pump are used to make state judgment, and the results shown in Table 1 are obtained. The simulation parameters are as follows: Δt = 1 ms; T = 100 ms; A th = 3 × 10 6 . It can be found that correct judgment results can be obtained when S ≥ 4 mm 2 and there is no leakage; however, when S = 2 mm 2 and 1 mm 2 , incorrect judgment results occur. This is mainly because when the leakage hole area is reduced to a certain extent, the change in the obtained amplitude before and after the water pump is pressurized will be less than the judgment threshold A th , so that the leakage is misjudged as normal.

[0081] Table 1 judgment results (A th = 3 × 10 6 )

[0082]

[0083] In order to improve the accuracy of the leakage judgment, A th is reduced to 1.5 × 10 6 in the simulation model, and the judgment results shown in Table 2 are obtained. It can be found that all the judgment results are correct. Therefore, reducing A th helps to improve the judgment accuracy in the leakage state.

[0084] Table 2 judgment results (A th = 1.5 × 10 6 )

[0085]

[0086] According to the above analysis results, A th is further reduced to 1.5 × 10 5 in this embodiment, and the judgment results shown in Table 3 are obtained.

[0087] Table 3 judgment results (A th = 1.5 × 10 5 )

[0088]

[0089] Unlike the results in Table 2, although correct judgment results can be obtained in the leakage case in Table 3, there will be a certain misjudgment probability in the case without leakage. This is mainly because in the case without leakage, due to the existence of random noise, the size relationship between the change in the amplitude before and after the water pump is pressurized and the judgment threshold A th has uncertainty.

[0090] According to the above analysis results, A thThe large A th will cause the misjudgment of small leakage hole; and the small A th will cause the misjudgment of no leakage. Therefore, in the system, the A th is required to be set reasonably according to the actual situation to improve the accuracy of the judgment.

[0091] In one embodiment of the present application, the leakage judgment module can further implement the multi-stage judgment of the leakage area, and the leakage grading judgment threshold B v1 is set in the leakage judgment module.

[0092] In the embodiment, when the leakage judgment module receives the instruction 1 sent by the state triggering module, the leakage judgment module enters the preparation state and clears the related registers. After receiving the first amplitude average value A v2 sent by the amplitude detection module, the value is stored in the register R1; after receiving the second amplitude average value A v1 sent by the amplitude detection module, the value is stored in the register R2. Finally, the difference between A v2 and A th is calculated and compared with the judgment threshold A th firstly. When the difference between the two average values is less than A th , it is judged as normal. When the difference between the two average values is greater than or equal to A th , it is further compared with the judgment threshold B th . When the difference between the two average values is less than B th , it is judged as small leakage; when the difference between the two average values is greater than or equal to B 2 , it is judged as large leakage.

[0093] The simulation model is constructed by using the leakage judgment module with the multi-stage judgment function, and the normalized vibration signals under different leakage hole areas are shown in FIG. 2. Similarly, the leakage hole areas S are 18 mm 2 , 14 mm 2 , 8 mm 2 , 5 mm 2 , 4 mm 2 , 2 mm 2 , 1 mm set and 0. The simulation parameters are as follows: f0=0.3 MPa; f p =0.5 MPa; k=0.005 MPa / s, t 6 =10 s, B=3×10 th ;△t=1 ms; T=100 ms; A 6 =1.5×10 th ; B 6 =3×10 th . The simulation results are shown in Table 4.

[0094] Table 4 Grading determination results (A th = 1.5 x 10 6 , B th = 3 x 10 6 )

[0095]

[0096] According to the simulation results, it can be found that when S≥4mm 2 , it is determined as large leakage; when S is 2mm 2 and 1mm 2 , it is determined as small leakage, and the grading monitoring of the healthy state is realized.

[0097] The above only lists specific embodiments of the present application. Obviously, the present application is not limited to the above embodiments, and there can be many variations. All variations that can be directly derived or thought of by those of ordinary skill in the art from the content disclosed by the present application should be considered as falling within the scope of protection of the present application.

Claims

1. A method of enhancing a leak signal of a tunnel fire water delivery pipe, characterized by, The method comprises the following steps: Step 1: adjusting the minimum set pressure and the maximum set pressure of the water pump to optimize the amplification of the leakage signal: ； wherein f0represents the minimum set pressure, f set represents the maximum set pressure, and r represents the leakage signal amplification rate. The water pump is started when the water pressure drops to the minimum set pressure and is stopped when the water pressure reaches the maximum set pressure, and the vibration signals of the water conveying pipeline before and after the water pump is pressurized are collected; Step 2: calculating the amplitudes of the vibration signals of the water conveying pipeline before and after the water pump is pressurized, and taking the amplitude difference as the leakage signal to be detected; Step 3: comparing the leakage signal to be detected with the first threshold value, if the leakage signal is greater than the first threshold value, then comparing the leakage signal with the second threshold value, if the leakage signal is greater than the second threshold value, then the water conveying pipeline has a large leakage, otherwise the water conveying pipeline has a small leakage; if the leakage signal is not greater than the first threshold value, then the water conveying pipeline is normal.

2. A tunnel fire water delivery conduit leak signal monitoring system characterized by, The tunnel fire-fighting water conveying pipeline is divided into several regions, and each region is provided with a vibration sensor; one end of the tunnel fire-fighting water conveying pipeline is provided with a water pump, and a pressure sensor is arranged at the outlet section of the water conveying pipeline of the water pump; The monitoring system comprises: A state triggering module for sending the working state instructions of the water pump, wherein the working state of the water pump comprises a pre-starting preparation state, a starting pressurization state and an ending pressurization state, which correspond to instruction 1, instruction 2 and instruction 3 respectively; the instructions are used to control the water pump to be started when the water pressure drops to the minimum set pressure and to be stopped when the water pressure reaches the maximum set pressure, and the amplification of the leakage signal is optimized by adjusting the minimum set pressure and the maximum set pressure of the water pump: ； wherein f0represents the minimum set pressure, f set represents the maximum set pressure, and r represents the leakage signal amplification rate. The working procedure of the state triggering module for sending the working state instructions is as follows: When the water pump just enters the pre-starting preparation state, the state triggering module sends the starting pressurization preparation instruction 1 to the amplitude detection module and the leakage judgment module; when the water pump just enters the starting pressurization state, the state triggering module sends the starting pressurization instruction 2 to the amplitude detection module and the leakage judgment module; when the water pump just enters the ending pressurization state, the state triggering module sends the ending pressurization instruction 3 to the amplitude detection module and the leakage judgment module; An amplitude detection module for sampling the vibration signals of the vibration sensors before and after the water pump is pressurized, and performing data processing in combination with the instructions sent by the state triggering module to calculate the amplitude average values of the vibration signals of the water conveying pipeline before and after the water pump is pressurized; A leakage judgment module for receiving the amplitude average values of the vibration signals of the water conveying pipeline before and after the water pump is pressurized sent by the amplitude detection module, and taking the amplitude difference as the leakage signal to be detected; The leakage signal is compared with the first threshold value, if the leakage signal is greater than the first threshold value, then the leakage signal is compared with the second threshold value, if the leakage signal is greater than the second threshold value, then the water conveying pipeline has a large leakage, otherwise the water conveying pipeline has a small leakage; if the leakage signal is not greater than the first threshold value, then the water conveying pipeline is normal.

3. The tunnel fire service water pipe leak signal monitoring system according to claim 2, characterized in that, When the amplitude detection module receives the instruction 1 sent by the state triggering module, the amplitude detection module starts to sample the vibration signals of the vibration sensors with △t as the time interval, and takes T as a vibration amplitude extraction period; in each vibration amplitude extraction period T, the maximum value and the minimum value of the vibration signals obtained by sampling are obtained by using the comparison method, and the maximum value is subtracted from the minimum value, so as to obtain the amplitude of each period T, and the amplitudes of the periods T are stored. When the amplitude detection module receives command 2 from 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 The average amplitude A stored in the time period v1 And send this value to the leakage detection module; where t p Indicates the time interval between instruction 1 and instruction 2; When the amplitude detection module receives the instruction 3 sent by the state triggering module, the amplitude detection module restarts sampling the vibration signal of the vibration sensor with△t as the time interval and 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 using the comparison method, and the maximum value is subtracted from the minimum value, so as to obtain the amplitude of each period T, and the amplitudes of the periods T are stored; after the time t p passes, the average value A v2 of the stored amplitudes is calculated and the value is sent to the leakage determination module.

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