CN105572329A - Concrete crack scale distance adaptive monitoring method - Google Patents

Abstract

The invention discloses a concrete crack scale distance adaptive monitoring method based on a distributed strain sensor array. The method comprises the steps:by taking the parallel distribution of distributed strain sensing elements as a basis, measuring strain data under a constant loading condition through a strain sensor array and a strain demodulation device at the inner part or the surface of a concrete matrix, applying a scale distance adaptive algorithm to analyze and process the strain data, and obtaining the current minimum scale distance as a damage area, wherein the measured strain data represents crack damage degree. The monitoring method provided by the invention is different from strain monitoring of fixed scale distance in focusing on the characteristic that the measured scale distance of strain monitoring can be customized according to a standard from a centimeter level to a meter level, and judging whether crack damage generates cross scale distance evolution or not through the strain data per se while performing damage diagnosis, so as to enable the current minimum scale distance to adapt to a changed damage hot spot area. According to the monitoring method provided by the invention, static strain data with test stability and relatively high accuracy is utilized without needing a known load and a numerical model, and the monitoring method is suitable for real-time on-line monitoring.

Description

Concrete cracks gauge length self-adaptive monitoring method

Technical field

The invention belongs to monitoring structural health conditions and modern detecting field, be specifically related to a kind of concrete cracks gauge length self-adaptive monitoring method based on distributed strain sensor array.

Background technology

In construction and the physics chemical action being subject to load action, environment and material itself during one's term of military service, very easily there is cracking phenomena in xoncrete structure.Suppress while unhealed cracks, utilize damage detection technology to carry out monitoring and diagnosis to concrete cracks very necessary.

Traditional crack detection mainly contains range estimation, New Instrument for Crack Width, ultrasound wave, acoustic emission, photography and Carlson, Evans Fordyce formula or string formula crack gauge etc., these methods all can reach certain measuring accuracy, but belong to artificial or point type detection, space scale is difficult to the crack information of oversite concrete structure randomness.Because Real-Time Monitoring, coverage are large, the advantage such as Spatial continual and high precision, distributed cognition technology is applied in concrete cracks monitoring gradually.The people such as Hale propose optical fiber the earliest as structural crack sensor; University of Toronto researcher proposes to fracture based on optical fiber the damage reason location system of principle, and the optical fiber output power when region a certain in structure is zero, can judge damage position thus; The people such as LeMaou utilize flush type multimode optical fiber to monitor concrete cracks, and technique successful Application in tunnel-liner, and detects the appearance of crackle.Leung causes intensity loss monitoring crack to expand based on optical fiber micro-bending, as long as direction of check and optical fiber oblique, this sensing probe just can the existence of perception xoncrete structure crackle.In recent years, researcher is by Rayleigh, Brillouin and Raman scattering characteristic, and by input pulse signal in optical cable, analyze its reflection (or transmission) signal, the strain data obtained by demodulation characterizes Crack Damage.But, because Crack Damage causes its test strain to reach more than 10%, far beyond the deformability of glass optical fiber, easily occur to shear brittle failure simultaneously, even if by Material cladding or according to strain transfer adjustment encapsulation, its strain range is difficult to more than 20,000 microstrains.In addition, somebody tentatively achieves Real-Time Monitoring (a kind of distributed crack sensor based on concentric cable of structural crack by the electric time domain reflection technology of high ductility concentric cable, application number: 201110027121.1), but the crack sensitivity of this kind of method, distributed testing and multiplexing capacity are still to be tested.In addition, existing distributed strain sensor uses the measurement gauge length preset, and large-length sensing probe is insensitive to Crack Damage commitment, easily causes damage to fail to judge; Due to the non-linear and randomness that Crack Damage develops, adopt the mean strain of fixing gauge length to portray crackle, also easily cause damage erroneous judgement.

For above-mentioned deficiency, consider that distributed strain monitoring information is while focusing structure local stress/strain is concentrated, also can covered structure damage field in a big way.The invention provides a kind of concrete cracks monitoring method of the adaptive algorithm based on multi-level measurement gauge length, concrete cracks is made to damage while there is the evolution across gauge length, suitable measurement gauge length can be adjusted voluntarily, and characterize Crack Damage by its strain data.

Summary of the invention

For the deficiencies in the prior art, the invention provides a kind of concrete cracks gauge length self-adaptive monitoring method based on distributed strain sensor array, by strain data itself, the method judges whether Crack Damage occurs to develop across gauge length while utilizing the strain sensing array detection and diagnosis concrete cracks damage of multi-level measurement gauge length.When Crack Damage evolution exceeds the overlay area of minimum gauge length, to select further and redefine current minimum gauge length, making it the Hot damage point region of Adaptive change, and then more accurately and robustly portray Crack Damage.

For achieving the above object, technical scheme of the present invention is:

Based on a concrete cracks gauge length self-adaptive monitoring method for distributed strain sensor array, mainly comprise the following steps:

The first step, adopt inner pre-buried or surperficial fixing mode, the strain sensing probe of the distributed strain sensing probe of parallel laying optical fiber and coaxial cable distribution on concrete substrate, by setting different measuring gauge length, form and there is the strain sensing array that multi-level (m level) measures gauge length;

Second step, measures gauge length to current all 1 to m levels and carries out permutation and combination, build all possible n gauge length sequence ${\left\{{\tilde{L}}_i\right\}}_j,\left(\begin{array}{cc}i=0,...,m-1& j=1,...,n\end{array}\right),$ Adopt above-mentioned strain sensing to pop one's head in and record the static strain data of concrete substrate under dead load with corresponding demodulated equipment described static strain data for repeatedly testing each gauge length sequence the mean value obtained;

3rd step, obtains static strain data by whether testing judge whether the corresponding strain sensing probe measuring gauge length damages: if do not record static strain data then strain sensing tip damage, repeats second step; If record static strain data then strain sensing probe does not damage, and carries out next step.

4th step, for each gauge length sequence to measure the gauge length L of gauge length _ifor transverse axis, to measure deflection Δ L corresponding to gauge length _ifor the longitudinal axis, set up plane right-angle coordinate, make multi-section-line L _i-Δ L _i.

5th step, with each gauge length sequence multi-section-line L under the concrete substrate health status surveyed _i-Δ L _ifor benchmark, according to the multi-section-line L of each gauge length sequence _i-Δ L _imove whether and judge whether Crack Damage occurs, if L _i-Δ L _imove on not occurring, repeat the 4th step; If L _i-Δ L _igeneration moves, then the concrete substrate that the gauge length sequence that multi-section-line is corresponding is surveyed damages, and according to the minimum gauge length determination Crack Damage region occurred in the gauge length sequence of damage and quantity thereof, carries out next step.

6th step, the multi-section-line L moved on occurring _i-Δ L _iin, if different stage measure gauge length corresponding on the amount of moving have marked difference, then the Crack Damage of concrete substrate that this gauge length sequence is surveyed occurs to develop across gauge length;

6.1 at this multi-section-line L _i-Δ L _iamong, a certain rank measure gauge length after all gauge lengths (gauge length is more than or equal to this grade of gauge length) corresponding on the amount of moving be greater than this grade of gauge length before all gauge lengths (gauge length is less than this gauge length) corresponding on the amount of moving, selecting this rank to measure gauge length is this multi-section-line L _i-Δ L _ithe current minimum gauge length of corresponding gauge length sequence;

6.2 occur in each damage field of the gauge length sequence of damage the 5th step is all, repeat step 6.1 and can obtain multiple current minimum gauge length, select the current minimum gauge length with minimum gauge length to be the current minimum gauge length of this damage field;

6.3 as determined the current minimum gauge length of each damage field, then get rid of gauge length in this gauge length sequence and are less than all gauge lengths of current minimum gauge length, and repeat second step to the 5th step;

7th step, the multi-section-line L moved on occurring _i-Δ L _iin, if different stage measure gauge length corresponding on the amount of moving without marked difference, then by each occur damage gauge length sequence in current minimum gauge length as damage field, on the strain data that records be used for characterizing Crack Damage degree, export diagnostic result.

Based on the present invention's parallel laying that strain sensing is popped one's head in a distributed manner, obtained the strain data under constant load condition by the strain sensing array that concrete substrate is inner or surperficial.The present invention focuses on strain monitoring to the sensitivity characteristic of structure partial Crack Damage, Distributed coverage ability and measure gauge length and can realize from centimetre to the intrinsic advantage of meter level customization, be different from traditionally based on the strain monitoring of fixing gauge length, and adopt above-described gauge length self-adaptive monitoring method, the method can adjust suitable measurement gauge length voluntarily, the Hot damage point region of Adaptive change, wherein gauge length adaptive algorithm is core content of the present invention.

Effect of the present invention and benefit are: 1) for the measurement gauge length of different stage in strain sensing array, adopt gauge length self-adaptive monitoring method to avoid: Crack Damage causes xoncrete structure local stress/strain to concentrate, cause little gauge length sensing probe to exceed self-deformation ability and be damaged and test cannot be continued; Because large-length sensing probe is insensitive to earlier damage, damage is caused to be failed to judge; Adopt the strain data of fixing gauge length to characterize Crack Damage, cause damage erroneous judgement.2) only utilize the static strain data under constant load effect, can realize stably testing and precision higher, and concrete load numerical value need not be considered.3) gauge length adaptive algorithm of the present invention need not the numerical model of structure, computation process is algebraic operation, greatly reduce calculated amount, be applicable to Real-Time Monitoring, can be the quick early warning of xoncrete structure and destroy collapse mechanism research technical support is provided, and be that the structure for health diagnosis of other damage characteristic is offered reference.

Accompanying drawing explanation

Fig. 1 is strain sensing array concrete cracks damage monitoring schematic diagram of the present invention;

Fig. 2 is gauge length adaptive algorithm block diagram of the present invention;

Fig. 3 is a certain gauge length sequence diagram of multi-level measurement gauge length (m=4) in embodiment;

Fig. 4 is the multi-section-line L of corresponding a certain gauge length sequence in embodiment _i-Δ L _i;

In figure, 1 is the strain sensing array that multi-level measurement gauge length is formed.

Embodiment

The specific embodiment of the present invention is described in detail below in conjunction with accompanying drawing:

Based on the present invention's parallel laying that strain sensing is popped one's head in a distributed manner, as shown in Figure 1, the strain sensing array 1 inner or surperficial by concrete substrate and strain demodulated equipment record the strain data under constant load condition.Carry out analyzing and processing to the deflection application gauge length adaptive algorithm corresponding to the measurement gauge lengths at different levels of each gauge length sequence, as shown in Figure 2, finally obtain current minimum gauge length as damage field, namely its strain data recorded characterizes Crack Damage degree.

Customize measurement gauge length according to Fig. 3, get the average of repeatedly testing the static strain data obtained $\left\{\begin{array}{cccc}\stackrel{-}{{\mathrm{\ϵ}}_0}& \stackrel{-}{{\mathrm{\ϵ}}_1}& \stackrel{-}{{\mathrm{\ϵ}}_2}& \stackrel{-}{{\mathrm{\ϵ}}_3}\end{array}\right\},$ Calculate measurement gauge length deflection { Δ L at different levels ₀Δ L ₁Δ L ₂Δ L ₃.Further, according to gauge length adaptive algorithm:

S1) (health) state is not damaged:

Sensing probe does not damage, and makes multi-section-line L _i-Δ L _i, as shown in solid line in Fig. 4.According to the resolution principle of static problem, under the condition that load is constant, measurement gauge length deflection at different levels does not change.

S2) there is (representing with footmark α) in damage:

Sensing probe does not damage, and makes multi-section-line as shown in dotted line long in Fig. 4.Multi-section-line moves, and measurement gauge length at different levels on the amount of moving equal.There is Crack Damage in concrete substrate, but does not occur to develop across gauge length.

Because the xoncrete structure local stiffness damaging rear minimum gauge length measured zone declines, this damage field is caused to increase in the internal strain of certain hour span, namely also can be written as in formula for damaging rear strain, δ _αfor strain relative increment, then have

${\mathrm{\ΔL}}_0^{\mathrm{\α}}={\stackrel{\‾}{\mathrm{\ϵ}}}_0^{\mathrm{\α}}{L}_0=\[(1+{\mathrm{\δ}}_{\mathrm{\α}}){\stackrel{\‾}{\mathrm{\ϵ}}}_0\]L_0={\mathrm{\ΔL}}_0+{\mathrm{\δ}}_{\mathrm{\α}}{\mathrm{\ΔL}}_0---\left(1\right)$

Damage according to strain equivalence principle and measurement gauge length AB section, obtain

${\mathrm{\ΔL}}_1^{\mathrm{\α}}={\mathrm{\ΔL}}_0^{\mathrm{\α}}+{\mathrm{\ΔL}}_{AB}^{\mathrm{\α}}={\mathrm{\ΔL}}_0+{\mathrm{\δ}}_{\mathrm{\α}}{\mathrm{\ΔL}}_0+{\mathrm{\ΔL}}_{AB}={\mathrm{\ΔL}}_1+{\mathrm{\δ}}_{\mathrm{\α}}{\mathrm{\ΔL}}_0---\left(2\right)$

In like manner can obtain

${\mathrm{\ΔL}}_2^{\mathrm{\α}}={\mathrm{\ΔL}}_2+{\mathrm{\δ}}_{\mathrm{\α}}{\mathrm{\ΔL}}_0---\left(3\right)$

${\mathrm{\ΔL}}_3^{\mathrm{\α}}={\mathrm{\ΔL}}_3+{\mathrm{\δ}}_{\mathrm{\α}}{\mathrm{\ΔL}}_0---\left(4\right)$

Phenomenon shown in long dotted line in Fig. 4 intuitively can be drawn by formula (1)-(4).Under current state, Crack Damage region is and with characterize Crack Damage degree.

S3) (representing with footmark β) is developed across gauge length:

Sensing probe does not damage, and makes multi-section-line as shown in short dash line in Fig. 4.Multi-section-line moves, and measurement gauge length at different levels on the amount of moving not etc., wherein measure gauge length multi-section-line on the amount of moving identical with upper example, on all the other gauge lengths, the amount of moving is identical and compare example and increase to some extent.The Crack Damage of concrete substrate there occurs the evolution across gauge length.

According to S2) example derivation, in like manner can obtain

${\mathrm{\ΔL}}_0^{\mathrm{\β}}={\mathrm{\ΔL}}_0+{\mathrm{\δ}}_{\mathrm{\α}}{\mathrm{\ΔL}}_0={\mathrm{\ΔL}}_0^{\mathrm{\α}}---\left(5\right)$

${\mathrm{\ΔL}}_1^{\mathrm{\β}}={\mathrm{\ΔL}}_1+{\mathrm{\δ}}_{\mathrm{\α}}{\mathrm{\ΔL}}_0+{\mathrm{\δ}}_{\mathrm{\β}}{\mathrm{\ΔL}}_{AB}---\left(6\right)$

${\mathrm{\ΔL}}_2^{\mathrm{\β}}={\mathrm{\ΔL}}_2+{\mathrm{\δ}}_{\mathrm{\α}}{\mathrm{\ΔL}}_0+{\mathrm{\δ}}_{\mathrm{\β}}{\mathrm{\ΔL}}_{AB}---\left(7\right)$

${\mathrm{\ΔL}}_3^{\mathrm{\β}}={\mathrm{\ΔL}}_3+{\mathrm{\δ}}_{\mathrm{\α}}{\mathrm{\ΔL}}_0+{\mathrm{\δ}}_{\mathrm{\β}}{\mathrm{\ΔL}}_{AB}---\left(8\right)$

δ in formula _βfor measuring the strain relative increment of gauge length AB section.

Select gauge length for current minimum gauge length, get rid of gauge length redefine gauge length sequence $\left\{\begin{array}{ccc}\widetilde{L_1}& \widetilde{L_2}& \widetilde{L_3}\end{array}\right\}.$ Now represent faulted condition corresponding to current minimum gauge length with footmark α β

${\mathrm{\ΔL}}_1^{\mathrm{\α}\mathrm{\β}}={\stackrel{\‾}{\mathrm{\ϵ}}}_1^{\mathrm{\α}\mathrm{\β}}{L}_1=\[(1+{\mathrm{\δ}}_{\mathrm{\α}\mathrm{\β}}){\stackrel{\‾}{\mathrm{\ϵ}}}_1\]L_1={\mathrm{\ΔL}}_1+{\mathrm{\δ}}_{\mathrm{\α}\mathrm{\β}}{\mathrm{\ΔL}}_1---\left(9\right)$

${\mathrm{\ΔL}}_2^{\mathrm{\α}\mathrm{\β}}={\mathrm{\ΔL}}_2+{\mathrm{\δ}}_{\mathrm{\α}\mathrm{\β}}{\mathrm{\ΔL}}_1---\left(10\right)$

${\mathrm{\ΔL}}_3^{\mathrm{\α}\mathrm{\β}}={\mathrm{\ΔL}}_3+{\mathrm{\δ}}_{\mathrm{\α}\mathrm{\β}}{\mathrm{\ΔL}}_1---\left(11\right)$

In formula for damaging rear strain, δ _{α β}for the strain relative increment of current minimum gauge length.

Phenomenon shown in short dash line in Fig. 4 intuitively can be drawn by formula (5)-(8); According to Crack Damage region under formula (9)-(11) current state be and with characterize Crack Damage degree.Above-mentioned derivation demonstrates the feasibility of the gauge length adaptive algorithm that the present invention proposes.

Above embodiment is only in order to illustrate technical scheme of the present invention and to have certain general preferred implementation; should be understood that; those skilled in the art are to be understood that; can also do under the prerequisite not departing from technical solution of the present invention and improve particularly, it all should be considered as of the present invention containing and protection domain.

Claims (2)

1. a concrete cracks gauge length self-adaptive monitoring method, is characterized in that, comprises the following steps:

The first step, the strain sensing probe of parallel laying optical fiber and coaxial cable distribution on concrete substrate, setting different measuring gauge length, forms the strain sensing array that m level measures gauge length;

Second step, measures gauge length permutation and combination to current all 1 to m level, builds n gauge length sequence adopt above-mentioned strain sensing to pop one's head in and record the static strain data of concrete substrate under dead load with corresponding demodulated equipment described static strain data for repeatedly testing each gauge length sequence the mean value obtained;

3rd step, by whether recording static strain data judge whether the corresponding strain sensing probe measuring gauge length damages, if do not record static strain data then strain sensing tip damage, repeats second step; If record static strain data then strain sensing probe does not damage, and carries out next step;

4th step, for each gauge length sequence to measure the gauge length L of gauge length _ifor transverse axis, to measure deflection Δ L corresponding to gauge length _ifor the longitudinal axis, set up plane right-angle coordinate, make multi-section-line L _i-Δ L _i;

5th step, with each gauge length sequence multi-section-line L under the concrete substrate health status surveyed _i-Δ L _ifor benchmark, according to the multi-section-line L of each gauge length sequence _i-Δ L _imove whether and judge whether Crack Damage occurs, if L _i-Δ L _ido not occur to move, repeat the 4th step; If L _i-Δ L _igeneration moves, then the concrete substrate that the gauge length sequence that multi-section-line is corresponding is surveyed damages, and by the minimum gauge length determination Crack Damage region occurred in the gauge length sequence of damage and quantity, carries out next step;

6th step, the multi-section-line L moved on occurring _i-Δ L _iin, if different stage measure gauge length corresponding on the amount of moving difference, then the Crack Damage of concrete substrate that this gauge length sequence is surveyed occurs to develop across gauge length;

6.1 at this multi-section-line L _i-Δ L _iamong, a certain rank measure gauge length after all gauge lengths corresponding on the amount of moving be greater than this grade of gauge length before all gauge lengths corresponding on the amount of moving, selecting this rank to measure gauge length is this multi-section-line L _i-Δ L _ithe current minimum gauge length of corresponding gauge length sequence;

6.2 occur in each damage field of the gauge length sequence of damage the 5th step is all, repeat step 6.1 and can obtain multiple current minimum gauge length, select the current minimum gauge length with minimum gauge length to be the current minimum gauge length of this damage field;

If the current minimum gauge length that 6.3 determine each damage field, then get rid of gauge length in this gauge length sequence and be less than all gauge lengths of current minimum gauge length, repeat second step to the 5th step;

7th step, the multi-section-line L moved on occurring _i-Δ L _iin, different stage measure gauge length corresponding on the amount of moving identical, then by each occur damage gauge length sequence in current minimum gauge length as damage field, on the strain data that records be used for characterizing Crack Damage degree, export diagnostic result.

2. a kind of concrete cracks gauge length self-adaptive monitoring method according to claim 1, is characterized in that, in the described first step, the inner pre-buried or surface of strain sensing probe is fixed on concrete substrate.