CN101393269A - Method for monitoring geology by utilizing communication optical cable - Google Patents

Abstract

The invention provides a method which uses widely-used communication optical cables to perform real-time monitoring on geological conditions in the area where optical cables are laid, judges the type of geological hazards according to the vibration information from the optical cables, and uses the difference between the seismic wave transmission speed and the light transmission speed to realize early warning function of seismic and the geological hazards; and the geological hazard monitoring method can transmit threatening strong earthquake information to various towns which can be threatened a few seconds or even more in advance so as to reduce the loss caused by a strong earthquake as possible. The geological hazard monitoring method can also be used for monitoring vicious incidents such as local geologic hazards like landslides and mudflows, and man-made destruction, and has the advantages of wide monitoring range, high sensitivity, good reliability, low cost and high utilization rate.

Description

A kind of method of utilizing communications optical cable monitoring geological state

Technical field

The present invention relates to a kind of method of utilizing communications optical cable monitoring optical cable laying regional geology situation, belong to photoelectricity monitoring, geology monitoring field.

Background technology

Over the past thousands of years, the geologic hazards such as earthquake, volcano, rubble flow and landslide that are difficult to expect cause the casualties and the property loss of not count enable.If a kind of system is arranged; can spread over the various regions that need warning of different places or areas simply, economically; has the inducing function of " assurance " accurate earth movement " pulse " rapidly; and can in time menace terrible disaster information transmission be arrived the cities and towns that each may be compromised; get the jump on that mountains collapse and the earth crack up gave the alarm before tens seconds; perhaps the people in disaster area just run away to sanctuary if having time, and combustion gas and Utilities Electric Co. just can take the emergency protection measure, and the train that quickly travels also can brake, save from damage passenger's life immediately.

With regard to earthquake, the used technology of having developed in the world at present of earthquake early-warning system all is based on the mistiming of the shear wave and the compressional wave of seismic event.Seismic event is divided into shear wave and compressional wave, and wherein shear wave is the main cause that causes disaster, but velocity of propagation is slower in the earth's crust, about 4km/s; The longitudinal wave propagation direction is consistent with the seismic oscillation direction, in the earth's crust, propagates comparatively fast, and about 7km/s, object can pitch when its arrives ground.Inferred to tens seconds in former seconds and focus, earthquake magnitude and earthquake intensity so can arrive at the big shear wave of destructive power, and be delivered to by data transmission media may affected area, allows these regional critical facilitys and the crowd is dense that the district can make emergency measure in tens seconds in advance.

Summary of the invention

The purpose of this invention is to provide a kind of present widely used communications optical cable that utilizes, the method that can monitor in real time optical cable laying areal geology situation, judge the kind of geologic hazard by the suffered vibration information of optical cable, and utilize the difference of seismic event transmission speed and light wave transmissions speed to realize seismogeology disaster alarm function.

Technology contents of the present invention is: a kind of method of utilizing communications optical cable monitoring geological state, and it judges the geological state in this optical cable laying area by the vibration information of communications optical cable, its step is as follows:

A. lay a communications optical cable in the monitoring area, as the monitor signal passage; The old circuit that lays, has 1 channel reservation can be utilized, also newly-designed lightguide cable link can be adopted;

B. the end at described communications optical cable is provided with the light feedback assembly, and its function is to adjust the light path polarization state, and the reflection incident optical signal can be finished to twice different extraction constantly of same vibration signal the optic cable vibration information extracting device;

C. the other end at described communications optical cable is provided with the optic cable vibration information extracting device, its function is to produce the detection laser signal, through the coupling mechanism beam split, form two ways of optical signals, by the same channel of described communications optical cable, through light feedback assembly reflection feedback, produce stable interference fringe more respectively, after the detector opto-electronic conversion, obtain the two-way interference signal;

D., the optic cable vibration information processing platform is set, and its function is that the two-way interference signal is reduced to the extraneous vibration signal, and vibration signal is analyzed, and judgement is earthquake or local environment disturbance, and the report of issue geological state.

The algorithm of described optic cable vibration information processing platform monitoring analysis geological state is as follows:

A. regularly read the two-way interference signal, and this signal is reduced to the extraneous vibration signal;

B. judge whether the extraneous vibration signal exists abnormal vibrations, if no abnormal vibration is then returned and continued to read next period two-way interference signal;

C. if there is abnormal vibrations, then vibration signal is carried out spectrum analysis;

Whether the frequency spectrum of d. judging vibration signal exists damaged point, if the damaged point of no frequency spectrum then is judged to be seismic disturbance, and the report of issue geological state;

E. if there is a damaged point of frequency spectrum, then the paddy of the damaged point of each rank frequency spectrum is deeply convinced that breath measures;

F. judge whether the damaged point of frequency spectrum is obvious, if obviously, then be judged to be the single-point disturbance, and issue geological state report, can deeply whether have by the paddy of the damaged point of each rank frequency spectrum to surpass the dark thresholding of paddy set and the damaged point of these frequencies and whether be the odd frequency multiplication and concern and judge whether the damaged point of frequency spectrum is obvious;

G. if the damaged point of frequency spectrum is not obvious, then be judged to be the multiple spot disturbance, and the report of issue geological state.

The present invention has utilized the optical fiber communication network that develops rapidly over nearly 20 years, makes up the geological state monitor message net of sensing, transmission unification, and the optical cable of having laid is exactly the geological state monitoring sensor, has expanded the monitored area scope significantly; Simultaneously, on existing communication network, need not to increase any sensor special spare, do not influence communication function.And have following characteristics:

1, monitoring range is wide, investment is little, utilization factor is high.

2, the warning message transmission speed is high, in fact, the geological state monitoring system that adopts fiber cable network to make up, its information transfer time is the light velocity, and the secondary wave velocity of propagation with harmfulness only is 4km/s.Huge like this velocity contrast can be striven for valuable time for saving from damage of more lives and properties.

3, there are relevant close ties the monitored area with object of protection.It must be the region that people's activity is arranged that network is laid, layout density also with the roughly proportional relation of the density of population.In other words, the high-risk zone that needs protection, this sensing network density is high more, and sensitivity, reliability are also high more.

4, the anti-damage property of Tu Chu total system.The optical fiber cable communication network distributes dense, and the modern looped network route technology reliably of widespread use, even if guarantee to have individual areas to rupture, destroy when macroseism and strong calamity, also still can warning message effectively be transmitted via network.

5, further develop system's derivation function, also can utilize this system to realize that early warning is carried out in the theft, eavesdropping, the destructive activity that the full spectrum of threats network are transported media security to the real-time monitoring of existing fiber cable network security.

Therefore, the system that utilizes the method for utilizing communications optical cable to monitor optical cable laying regional geology situation of the present invention to construct can shift to an earlier date tens of seconds even the more time arrives the cities and towns that each may be compromised with menace macroseism information transmission, reduces the loss that macroseism is brought as far as possible; This system can also pass to the people that may suffer from disaster with information such as rubble flow and mountain torrents in advance, to keep one's head above water; This system also can be used for monitoring incidents such as the landslide of optical cable laying work area and artificial destruction.

Description of drawings

Fig. 1 is a monitoring analysis process flow diagram of the present invention;

Fig. 2 is the disturbance synoptic diagram of seismic event to optical cable;

Fig. 3 experiences the artificial disturbance synoptic diagram for optical cable;

Fig. 4 is the disturbance synoptic diagram of landslide to optical cable;

Fig. 5 experiences the spectrum waveform figure of disturbance on a large scale for optical cable;

Fig. 6 experiences the spectrum waveform figure of single-point disturbance for optical cable;

Fig. 7 experiences the spectrum waveform figure of disturbance among a small circle for optical cable.

Embodiment

The geological state monitoring system constructed according to the inventive method is made of four parts, the communications optical cable of first for laying, and second portion is the light feedback assembly, connects an end of the communications optical cable of being laid; Third part is the optic cable vibration information extracting device, connects the other end of the communications optical cable of laying; The 4th part is the optic cable vibration information processing platform, connects the vibration information extraction element.

Communications optical cable takies 1 channel in the communication line.Can be applicable to lay, have the old circuit of 1 channel reservation, also can be applicable in the new designed lines.The system monitoring scope can reach more than 100 kilometers.

The function of light feedback assembly is the reflection incident optical signal, adjusts the light path polarization state, and the optic cable vibration information extracting device can be finished twice different extraction constantly of same vibration signal.

The characteristics of light feedback assembly are to realize that not only the light positive that transmits passes through disturbance point twice in the other direction, under the environment of identical outer signals excitation, make phse sensitivity double, and can avoid of the influence of optical fiber (being equivalent to a phase-modulator) the polarization state random variation at disturbance point place effectively interference system; Simultaneously, the simple optical fiber that can realize phase-modulated information extracts.

When light wave was the optical fiber one time of l by length, the phase delay of generation was

Φ＝βl (1)

β is the propagation constant of light wave in optical fiber in the formula, β=nk ₀Wherein n is the effective refractive index that light wave is propagated in optical fiber, k ₀Be light wave wave number in a vacuum.

When length is that the optical fiber of l is subjected to outer signals when modulation, the variation that produces phase of light wave as sensing unit (the one section optical fiber that is equivalent to the disturbance point place)

For

Further arrangement turns to

Outer signals causes that the phase differential of light wave can describe with following formula, mainly comprises two, and first phase differential that the length for optical fiber takes place to cause when changing relatively generally caused by strain effect; Second phase differential that causes for the relative variation of light wave propagation constant mainly caused by electrooptical effect, elasto-optical effect, poisson effect and thermo-optic effect etc.The while phase differential

Proportional with the phase delay Φ that optical fiber causes.Under the certain situation of extraneous pumping signal, promptly

Necessarily, in order to wait until higher phse sensitivity, obviously can realize by the method that increases the sensor fibre length l, general realization approach is to increase actual fiber lengths, and the present invention adopts the light wave method that twice is passed through in optical fiber, do not increasing under the optical fiber physical length situation, it is 2 Φ effects that actual phase postpones, and the phase differential that obviously adopts in this respect us to wait until is

As seen under identical outer signals excitation, adopt light wave in sensor fibre, to pass through twice technical scheme, obtain the multiplication effect of phase differential, realized that promptly phse sensitivity doubles.So this type of phase modulating method except being applied to the fiber orientation monitoring system, can also be widely used in Fibre Optical Sensor, fiber optic communication field.

The feedback assembly of realizing said method is by two kinds of selections, and one is for adopting the mode at sensor fibre end face plating reflectance coating, is coupled to again in the optical fiber after making light in the optical fiber arrive end face, and the reflectance coating of this moment can be used as level crossing and handles; It two adopts faraday's rotating mirror at fiber end face, makes when light is reflected, and the polarization surface half-twist, and then be coupled to and realized double modulation in the sensor fibre.In the fiber optic interferometric system, all can run into the random perturbation problem of polarization state, when serious, can cause interference fringe to disappear.Adopt above-mentioned feedback assembly, the polarization state that takes place in the time of can effectively overcoming external disturbance and act on the sensor fibre changes the interference fringe that causes and disappears.

The function of optic cable vibration information extracting device is to extract acting on the various vibration informations of laying on the optical cable.Any one earthquake all shows as the vibration to environment, " bullet light " effect according to optical fiber, any vibration can cause that all the transmission light path changes in the optical cable, utilizes optical fiber vibration sensing technology in early stage (patent: full fiber-optic vibration measurement mechanism, the patent No.: ZL03229729.7; Make up the method for optical fiber feedback delay and the full light fiber white light interference system of structure thereof, the patent No.: ZL200410093482.6), can effectively realize detection to the optical cable ambient vibration.

Specifically, the optic cable vibration information extracting device is a kind of white light interference formula full optical fiber interference device, mainly is made up of laser instrument, full optical fiber interference device and data handling system.Wherein the full optical fiber interference device can be made up of three 2 * 2 fiber couplers, also can form by one 2 * 2 fiber coupler and one 3 * 3 fiber coupler, after laser is interfered through coupling mechanism beam split, difference frequency, direct measuring vibrations object, produce stable interference fringe, after the detector opto-electronic conversion, obtain the two-way interference signal.

Its principle of work is: the structure light path makes that the light wave that conducts in the optical fiber is different and comes and goes by disturbance point (vibration that causes during illegal invasion) constantly, supposes that at the moment t transmission phase of light wave that single angular frequency disturbing signal causes is changed to Then:

(5)

At moment t+ τ, the transmission phase of light wave that single angular frequency disturbing signal causes is changed to:

(6)

Disturbance point is made as L from the distance of light feedback assembly, and the time that the light round-trip transmission is twice is T, then:

T＝2n _effL/c

(7)

In the following formula, n _EffBe the fiber core equivalent refractive index, c is the light velocity in the vacuum.Because the disturbance of monitoring optical fiber makes the phase differential that forms in the interference system For:

$=2\sin \mathrm{\ω}(t+\mathrm{\τ}+\frac{T}{2})\·\cos \frac{\mathrm{\ωT}}{2}-2\sin \mathrm{\ω}(t+\frac{T}{2})\·\cos \frac{\mathrm{\ωT}}{2}$

$=4\cos \frac{\mathrm{\ωT}}{2}\sin \frac{\mathrm{\ω\τ}}{2}\cos \mathrm{\ω}(t+\frac{\mathrm{\τ}+T}{2})$

(8)

Can obtain time dependent output power at two output ports that install is:

(9)

(10)

Wherein A, B are and a relevant constant of input optical power size, Ψ ₂, Ψ ₂Be the initial phase of system, can be considered as constant; By every processes such as straight, normalization, can be with phase differential

Be expressed as:

(11)

Phase differential Reacting condition the size of external disturbance signal, therefore as long as will by algorithm

Inverting is come out, and just can finish the abstraction function of vibration signal to external world.This can insert computing machine with data collecting card with the two-way interference signal and realize by software, is the part of functions of the optic cable vibration information processing platform.

The function of the optic cable vibration information processing platform is that the two-way interference signal is reduced to the extraneous vibration signal, and vibration signal is analyzed, and judgement is earthquake or local environment disturbance, and this is the core technology of total system, and its analytical algorithm is seen Fig. 1.Earthquake causes that ground vibration is a regional issue, is not certain vibration that a bit takes place.According to this characteristic of earthquake, necessarily there is such fact, earthquake must be long distance to the disturbance region of optical cable, as shown in Figure 2.General landslide and artificial disturbance are short-range to the disturbance of optical cable, as shown in Figure 3 and Figure 4.Utilize the technological accumulation in early stage, the system that we make up utilizes and has the damaged characteristic of frequency in the rumble spectrum characteristic, can accurately determine the particular location of extraneous local dip.If (more than 1 kilometer) disturbance has taken place on a large scale the optical cable laying environment, we are defined as earthquake and take place.In this case, system can accurately determine earthquake generation incident according to damaged these characteristics that do not exist of rumble spectrum characteristic medium frequency.

The principle that the damaged point of frequency spectrum produces is based on when disturbing signal acts on sensor fibre, and system can't respond to a certain periodic characteristic frequency in the disturbing signal, and it is right to show as

Make after the Fast Fourier Transform (FFT) amplitude that the amplitude of these a series of feature forcing frequency correspondences on the spectrum domain is significantly less than all side frequency correspondences, have so-called " trap point ", can position disturbance point according to the position of " trap point ".Make a concrete analysis of as follows:

By (8) formula as can be known: when $\cos \frac{\mathrm{\ωT}}{2}\sin \frac{\mathrm{\ω\τ}}{2}\≠0$ The time,

Change fast in time, the output interference signal that this moment, photodetector detected is the slowly variable of concussion of an amplitude; When $\cos \frac{\mathrm{\ωT}}{2}\sin \frac{\mathrm{\ω\τ}}{2}=\≠0$ The time, the of ac of output is zero, i.e. P _1,2(t) not changing in time, is a constant.

When $\cos \frac{\mathrm{\ωT}}{2}=0$ The time, $\frac{\mathrm{\ωT}}{2}=\mathrm{k\π}-\frac{\mathrm{\π}}{2},$ Wherein k is a natural number; With (7) formula substitution, the note characteristic frequency is f _Null(k), then:

$f_{\mathrm{null}}\left(k\right)=\frac{2k-1}{2T}=\frac{2k-1}{2}\·\frac{c}{{2n}_{\mathrm{eff}}L}$

(12)

In like manner, when $\sin \frac{\mathrm{\ω\τ}}{2}=0$ The time, $f\′\left(k\right)=\frac{k-1}{\mathrm{\τ}},$ Wherein k is a natural number, and τ is time delay.

Because τ can obtain very little, corresponding with it first characteristic frequency f ' _K=1Just very big, promptly on frequency spectrum, it is far that the corresponding frequency spectrum defect location departs from zero point, chooses suitable τ and k value like this and just can avoid f ' (k) to f _Null(k) interference.

Therefore, the optic cable vibration information processing platform at first judges whether to thanks for your hospitality the movable property life by the amplitude size of two-way interference signal time domain waveform, if having, it is reduced to the extraneous vibration signal again, again signal processing methods such as its utilization spectrum analysis are tried to achieve rumble spectrum, can obtain damaged spectrum value f _Null(k).But, then do not have damaged point on the frequency spectrum and produce if disturbance is large-area.Utilize whether this feature decidable is the disturbance that earthquake produces.

Specifically, can be divided into following step:

1. regularly read the two-way interference signal, and this signal is reduced to the extraneous vibration signal;

2. judge whether the extraneous vibration signal exists abnormal vibrations, if no abnormal vibration is then returned and continued to read next period two-way interference signal;

3. if there is abnormal vibrations, then vibration signal is carried out spectrum analysis;

4. whether the frequency spectrum of judging vibration signal exists damaged point, if the damaged point of no frequency spectrum then is judged to be seismic disturbance, as shown in Figure 5, and the report of issue geological state;

5. if there is a damaged point of frequency spectrum, then the paddy of the damaged point of frequency spectrum is deeply convinced that breath measures;

6. judge whether the damaged point of frequency spectrum is obvious, if obviously, then be judged to be the single-point disturbance, as shown in Figure 6, and issue geological state report, can deeply whether to have by the paddy of the damaged point of each rank frequency spectrum to surpass the dark thresholding of paddy set and the damaged point of these frequencies and whether be the odd frequency multiplication and concern and judge whether the damaged point of frequency spectrum is obvious;

7. if the damaged point of frequency spectrum is not obvious, then be judged to be the multiple spot disturbance, as shown in Figure 7, and the report of issue geological state.

Because light wave transmissions speed is much larger than the seismic event transmission speed, so can utilize this speed difference to realize warning function fully.System can shift to an earlier date tens of seconds menace macroseism information transmission is arrived the cities and towns that each may be compromised, reduces the loss that macroseism is brought as far as possible.

In addition, because whole monitoring system and communication system are shared circuit hardware, the geological state information that obtains can be published to each communication terminal at the optical cable that the very first time passes through to be laid, by medium such as SMS, TV, broadcasting information such as earthquake warning are informed to the common people, further gain time for shock-absorbing.

Claims (3)

1. method of utilizing communications optical cable monitoring geological state is characterized in that: it judges the geological state in this optical cable laying area by the vibration information of communications optical cable, and its step is as follows:

A. lay a communications optical cable in the monitoring area, as the detection signal passage;

B. the end at described communications optical cable is provided with the light feedback assembly, and its function is to adjust the light path polarization state, and the reflection incident optical signal can be finished to twice different extraction constantly of same vibration signal the optic cable vibration information extracting device;

C. the other end at described communications optical cable is provided with the optic cable vibration information extracting device, its function is to produce the detection laser signal, through the coupling mechanism beam split, form two ways of optical signals, by the same channel of described communications optical cable, through light feedback assembly reflection feedback, produce stable interference fringe more respectively, after the detector opto-electronic conversion, obtain the two-way interference signal;

D., the optic cable vibration information processing platform is set, and its function is that the two-way interference signal is reduced to the extraneous vibration signal, and vibration signal is analyzed, and judgement is earthquake or local environment disturbance, and the report of issue geological state.

2. a kind of method of utilizing communications optical cable monitoring geological state according to claim 1, it is characterized in that: the algorithm of described optic cable vibration information processing platform monitoring analysis geological state is as follows:

A. regularly read the two-way interference signal, and this signal is reduced to the extraneous vibration signal;

B. judge whether the extraneous vibration signal exists abnormal vibrations, if no abnormal vibration is then returned and continued to read next period two-way interference signal;

C. if there is abnormal vibrations, then vibration signal is carried out spectrum analysis;

Whether the frequency spectrum of d. judging vibration signal exists damaged point, if the damaged point of no frequency spectrum then is judged to be seismic disturbance, and the report of issue geological state;

E. if there is a damaged point of frequency spectrum, then the paddy of the damaged point of frequency spectrum is deeply convinced that breath measures;

F. judge whether the damaged point of frequency spectrum is obvious, if obviously, then be judged to be the single-point disturbance, and issue geological state report, can deeply whether have by the paddy of the damaged point of each rank frequency spectrum to surpass the dark thresholding of paddy set and the damaged point of these frequencies and whether be the odd frequency multiplication and concern and judge whether the damaged point of frequency spectrum is obvious;

G. if the damaged point of frequency spectrum is not obvious, then be judged to be the multiple spot disturbance, and the report of issue geological state.

3. a kind of method of utilizing communications optical cable monitoring geological state according to claim 1 and 2, it is characterized in that: described communications optical cable can utilize and lay, have the old circuit of 1 channel reservation, also can adopt newly-designed lightguide cable link.

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