CN1945307A - Method for determining damage position of anchor rod system - Google Patents

Abstract

The nondestructive flaw detecting process for determining the damage position in anchor bolt-wall rock structure system includes the following steps: performing three layer wavelet packet resolving of the measured damage anchor bolt time domain signal u(s, t) with the db1 wavelet function of Daubechies wavelet series to obtain the low frequency and high frequency coefficients of different layers; performing threshold denoising treatment on the high frequency coefficients of the obtained signal; performing the one-leg reconstruction of the high frequency coefficients of the denoised signal to obtain the reconstructed oscillogram; recognizing the incident wave from the reconstructed oscillogram, anchor bottom reflection wave and sudden signal change position t0, te and ti; and final calculating to obtain the anchor bolt length L=C.(te-t0)/2 and anchor bolt damage position Li=C.(ti-t0)/2, where, C is the wave speed 5054 m/s. The method can determine the anchor bolt damage position precisely.

Description

A kind of method for determining damage position of anchor rod system

Technical field

The present invention relates to the method for a kind of engineering structure system nondestructive examination, particularly a kind of anchor pole-surrounding rock structure system determines the nondestructive means of its damage position.

Background technology

As everyone knows, the primary task of nondestructive examination of anchor pole-surrounding rock structure system is exactly to determine the position damaged.When damage appears in anchor rod system, the speed time-domain curve that its masthead records will be undergone mutation, promptly reflection wave occurs with looking into or anti-phase wavelet peak at the bottom of bar, the method of determining damage position is at present judged the damage position of anchor rod system normally by detecting the time difference between catastrophe point and the incident wave crest or converting the signal on the frequency domain by detecting the frequency peak separation.Their limitation is only to have considered respectively the feature of time domain or frequency domain, and fails time-domain and frequency-domain is combined the singularity of signal information of taking all factors into consideration correspondence when damage appears in anchor pole.Time domain approach can't be learnt its response at frequency domain, does not promptly know concentrated which frequency range that appears at of damage; And frequency domain method can only be determined the bulk property of a Signal Singularity, and is difficult to determine position and the distribution situation of singular point in the space, and promptly not knowing to damage is the phase place situation of damage reflection wave that when produce and concrete.In addition, because low deformation dynamic inspection signal is fainter, add The noise, the determining of sudden signal change position influenced by technician's human factor, is difficult to accurately obtain damaged location.

Summary of the invention

The object of the present invention is to provide a kind of method for determining damage position of anchor rod system, it can consider the information of time domain and frequency domain simultaneously, judges the anchor rod system damaged location exactly.

Everybody understands that singular point in the signal and irregular sudden change part often have important information, and it is one of important feature of signal.The damage of anchor rod system mainly shows as mortar and country rock to the loss or the inefficacy of anchor bar body anchoring, is embodied in the variation of bar side equivalent stiffness coefficient and ratio of damping on the mathematical model.The catastrophe point that wavelet transformation can extract signal by multiscale analysis is a singular point, the present invention mainly utilizes the modulus maximum point of wavelet transformation and the relation between the Singular Point to come reflected signal local singularity feature, thereby diagnose out damage position of anchor rod system, this method can be considered the information of time domain and frequency domain simultaneously.

The object of the present invention is achieved like this: a kind of method for determining damage position of anchor rod system is characterized in that it adopts following steps to determine:

A. to measured damage anchor pole time-domain signal u (s, t) the db1 wavelet function with Daubechies small echo series carries out three layers of WAVELET PACKET DECOMPOSITION, obtains each layer low frequency and high frequency coefficient;

B. the high frequency coefficient to the gained signal carries out the threshold value denoising Processing;

C. the high frequency coefficient through the signal of denoising Processing is partly carried out single reconstruct, obtain the oscillogram after the reconstruct;

D. reflection involves sudden signal change position t discern incident wave, bar from the oscillogram of reconstruct at the bottom of ₀, t _e, t _i

E. calculate rock-bolt length L=C (t _e-t ₀)/2, anchor pole damage position L _i=C (t _i-t ₀)/2, wherein C is a velocity of wave,

$C=\sqrt{\mathrm{\ρ}/E}=5054m/s.$

The catastrophe point that the present invention mainly utilizes wavelet transformation to extract signal by multiscale analysis is a singular point, its ultimate principle is that the modulus maximum of its continuous wavelet transform increases with the increase of yardstick when near the Lipschitz index a of signal singular point＞0; When a＜0, then the increase with yardstick reduces.The Lipschitz index of noise correspondence is much smaller than 0, and therefore the Lipschitz index of signal edge correspondence, utilizes wavelet transformation can distinguish noise and signal edge more than or equal to 0, and can detect the signal edge effectively is gradual or sudden change.

The damage of anchor rod system can cause the observation signal of system to change usually, when adopting certain measure to eliminate the noise effect that causes because of extraneous factor, directly utilizes the singular point of wavelet decomposition change detection observation signal just can detect the anchor pole damage position.The present invention utilizes the relation of the modulus maximum of singular point and wavelet transformation in the wavelet transformation to determine singular point, the modulus maximum of wavelet transformation all is to appear at the place that signal has sudden change, and the radio-frequency component at catastrophe point place is more, so the singular point of function can detect from the modulus maximum of the HFS of its wavelet transformation.If comprise transient signal in the signal, then in the due in and the place yardstick section (frequency band) of signal, signal energy will have a sudden change, show on the wavelet transform dimension spectrogram to be exactly on corresponding time-dimension location the spike projection to be arranged.Therefore, by detecting the Rush Hour of wavelet transform dimension-spectrogram upper process, just can realize detection to the transient signal due in.

Description of drawings

The complete anchor pole model of Fig. 1-1 synoptic diagram;

Fig. 1-2 to Fig. 1-the 4th, the wavelet decomposition catastrophe point detection figure of complete anchor pole signal;

Fig. 2-1 has damage anchor pole model 1 model synoptic diagram;

Fig. 2-2 is to Fig. 2-the 4th, to the wavelet decomposition catastrophe point detection figure of damage anchor pole model 1 signal is arranged;

Fig. 3-1 has damage anchor pole model 2 model synoptic diagram;

Fig. 3-2 is to Fig. 3-the 4th, to the wavelet decomposition catastrophe point detection figure of damage anchor pole model 2 signals is arranged.

In Fig. 1-1, the 1st, the II level fining twisted steel of diameter 28mm; 2 is 1: 2 sand-cement slurry; The 5th, pvc pipe.Fig. 1-2 is original signal figure.Fig. 1-the 3rd, signal HFS restructuring graph.Fig. 1-4 partly carries out single restructuring graph through the signal high frequency coefficient of denoising Processing, and wherein A is a direct wave, and B is a reflection wave at the bottom of the bar.

In Fig. 2-1, the 1st, the II level fining twisted steel of diameter 28mm; 2 is 1: 2 sand-cement slurry; The 3rd, dried fine sand; The 4th, the outsourcing oilpaper is coated with butter; The 5th, pvc pipe.Fig. 2-the 2nd, original signal figure.Fig. 2-the 3rd, signal HFS restructuring graph.Fig. 2-4 partly carries out single restructuring graph through the signal high frequency coefficient of denoising Processing, and wherein A is a direct wave, and B is a reflection wave at the bottom of the bar, and C is the defect interface reflection wave.

In Fig. 3-1, the 1st, the II level fining twisted steel of diameter 28mm; 2 is 1: 2 sand-cement slurry; The 3rd, gypsum putty; 4 is 1: 3 sand-cement slurry; The 5th, pvc pipe.Fig. 3-the 2nd, original signal figure.Fig. 3-the 3rd, signal HFS restructuring graph.Fig. 3-4 partly carries out single restructuring graph through the signal high frequency coefficient of denoising Processing, and wherein A is a direct wave, and B is a reflection wave at the bottom of the bar, and C is the defect interface reflection wave.

Embodiment

Below in conjunction with embodiment and above-mentioned accompanying drawing the present invention is further described, to embody the feasibility and the accuracy of the method for the invention.

Embodiment 1: get length and be 2.9 meters complete anchor pole, see Fig. 1-1, survey the detection that signal illustrates the fault-signal catastrophe point to its rod end knocking gained is moving.

The sudden change of considering signal produces a large amount of radio-frequency components, at first with electric signal through wavelet decomposition, the radio-frequency head of reconstruction signal assigns to determine the signal variation of undergoing mutation then.This example utilizes the wavelet decomposition that MATLAB provides and the power function of reconstruct that signal is handled, and original signal is seen Fig. 1-2, selects for use the db1 wavelet function of Daubechies small echo series to carry out three layers as wavelet basis here and decomposes and reconstruct, sees Fig. 1-3.As can be seen, the variation that high fdrequency component took place of signal is more obvious, because radio-frequency component is necessarily contained at the catastrophe point place, can be clear that the part of undergoing mutation by the reconstructed high frequency part.

Do not associate and see among the figure yet, when undergoing mutation, signal often produces a large amount of noise informations, only from figure, be difficult to judge the concrete time of catastrophe point, can utilize the modulus maximum of the wavelet transformation at catastrophe point place to determine catastrophe point, its basic skills is by setting a threshold value, the mould value of the wavelet coefficient of signal is neglected less than the wavelet module value of the point of a certain value, because the WAVELET TRANSFORM MODULUS value of noise is often smaller, can remove the influence of noise section by setting this threshold value, referring to Fig. 1-4.The data that from Fig. 1-4, read, according to the moment of direct wave and reflection wave arrival, calculate rock-bolt length:

t ₀=0.94ms, t _e=2.09ms, calculate the gained rock-bolt length:

L＝C·(t _e-t ₀)/2＝5054×(2.09-0.94)/2×10 ^-3＝2.906m

The length of the complete anchor pole that this example adopted is 2.9 meters, this shows, utilizes the more accurately length of measuring anchor rod of this method.

Embodiment 2: get a damage anchor pole model 1, see 2-1, its length is 2.9 meters, and two damage interfaces are arranged, and the position lays respectively at 1 meter and 1.9 meters apart from rod end, the moving survey of its rod end knocking gained signal is illustrated the detection of fault-signal catastrophe point.

1, (s t) (sees Fig. 2-2), carries out three layers of WAVELET PACKET DECOMPOSITION with the db1 wavelet function of Daubechies small echo series, and is reconstructed, and sees Fig. 2-3 to measured anchor pole time-domain signal u;

2, the high frequency coefficient to the gained signal carries out the threshold value denoising Processing;

3, the high frequency coefficient through the signal of denoising Processing is partly carried out single reconstruct, obtain the oscillogram after the reconstruct, see Fig. 2-4;

4, discern from the oscillogram of reconstruct that reflection involves sudden signal change position t at the bottom of incident wave, the bar ₀, t _e, t _i

5, calculate rock-bolt length L=C (t _e-t ₀)/2, anchor pole damage position L _i=C (t _i-t ₀)/2, wherein C is a velocity of wave,

$C=\sqrt{\mathrm{\ρ}/E}=5054m/s.$

From Fig. 2-4, can get:

t ₀=1.12ms, t ₁=1.52ms, t ₂=1.88ms, t ₁=2.29ms, result of calculation is:

First damages interface location: L ₁=C (t ₁-t ₀)/2=5054 * (1.52-1.12)/2 * 10 ^-3=1.011m

Second damage interface location: L ₂=C (t ₂-t ₀)/2=5054 * (1.88-1.12)/2 * 10 ^-3=1.920m

Rock-bolt length: L=C (t _e-t ₀)/2=5054 * (2.29-1.12)/2 * 10 ^-3=2.957m

Adopt damage position and rock-bolt length set in said method damage position that records and the anchor pole model 1 that is provided to coincide.

Embodiment 3: get a damage anchor pole model 2, see 3-1, its length is 2.9 meters, and two damage interfaces are arranged, and the position lays respectively at 1 meter and 1.9 meters apart from rod end, the moving survey of its rod end knocking gained signal is illustrated the detection of fault-signal catastrophe point.

Adopt embodiment 2 identical methods to detect, obtain the coherent detection figure of Fig. 3-2, from Fig. 3-4, can get to Fig. 3-4:

t ₀=0.14ms, t ₁=0.55ms, t ₂=0.89ms, t ₁=1.29ms, result of calculation is:

First damages interface location: L ₁=C (t ₁-t ₀)/2=5054 * (0.55-0.14)/2 * 10 ^-3=1.036m

Second damage interface location: L ₂=C (t ₂-t ₀)/2=5054 * (0.55-0.14)/2 * 10 ^-3=1.895m

Rock-bolt length: L=C (t _e-t ₀)/2=5054 * (1.29-0.14)/2 * 10 ^-3=2.906m

Can further confirm by above-mentioned result of calculation, adopt damage position and rock-bolt length set in the result that institute of the present invention method records and the anchor pole model 2 that is provided to coincide, illustrate that the method for the invention can comparatively accurately determine the impaired position of anchor pole.

Claims (1)

1, a kind of method for determining damage position of anchor rod system is characterized in that, it adopts following steps to determine:

A. to measured damage anchor pole time-domain signal u (s, t) the db1 wavelet function with Daubechies small echo series carries out three layers of WAVELET PACKET DECOMPOSITION, obtains each layer low frequency and high frequency coefficient;

B. the high frequency coefficient to the gained signal carries out the threshold value denoising Processing;

C. the high frequency coefficient through the signal of denoising Processing is partly carried out single reconstruct, obtain the oscillogram after the reconstruct;

D. reflection involves sudden signal change position t discern incident wave, bar from the oscillogram of reconstruct at the bottom of ₀, t _e, t _i

E. calculate rock-bolt length L=C (t _e-t ₀)/2, anchor pole damage position L _i=C (t _i-t ₀)/2, wherein C is a velocity of wave, $C=\sqrt{\mathrm{\ρ}/E}=5054m/s.$

Images