CN101033617A - Dynamic detecting method for basic structure testing signal - Google Patents

Abstract

A method to detect testing signals of basic structure dynamically. It contains the following steps: (1) Equip sensors on both sides of pile body below the tested pile block symmetrically. (2) Knock the top of pile foundation to get a signal while testing. (3) Record the signal by sensors. (4) Signals from the two sensors are transferred to signal smoothing module. Treat and combine the two signals based on the swing and sound rate and implement curve smoothing on the high frequency part of the signal. (5) Utilize low band filter to realize signal silence. (6) Transfer the silent signal to signal treatment module for integrality analysis of pile foundation. The invention provides a method to detect testing signals of basic structure dynamically, which can eliminate noise effectively and has high testing accuracy.

Description

A kind of dynamic testing method of basic structure testing signal

(1) technical field

The present invention relates to a kind of dynamic testing method of basic structure testing signal.

(2) background technology

Foundation structure mainly is meant the various piling strtuctures of building below ground, and it has obtained using widely in engineerings such as highrise building, heavy factory building, bridge construction, offshore platform, water conservancy projects and nuclear power stations.According to incompletely statistics, the average annual consumption of China present pile foundation mechanism is with 1,000,000 calculating, and actual building cost accounts for percent 20 to percent 30 of total investment of engineering.Because the quality of foundation structure is subjected to a lot of condition effect such as execution conditions very big, and mostly be concealed work, the large percentage of defective stake, this influence to the integrated engineering quality is serious, therefore, these foundation structures are carried out effectively, detected the diagnosis of examining hidden danger reliably, accurately, and the correct assessment of workmanship more and more comes into one's own.

The castinplace pile of various in recent years dissimilar and different construction is in the extensive application of various places, it monitored reliably and detects seem particularly important and urgent.Present dynamic testing method based on routine, owing to be subjected to self and environmental vibration The noise of measuring system, certainty of measurement is the limit of measuring method closely, the small-signal the when signal that causes owing to defective in the time of can't therefrom telling owing to or ground more complicated long in pile foundation is more weak.Do not use multiple detecting informations such as displacement, frequency displacement with fashion, it is bigger that the deduction of foundation structure quality is subjected to subjective influence, and complicated operation.

Because the system problem on foundation structure ground is very complicated, the information data that measuring system measures is insufficient, so the part defective is often covered by noise with the radiation information of stake point, used CAPWAP computational methods do not have to accomplish automatic Iterative or optimization at present, various curve fit processes also must be taked interactive method at present, rely on the engineer through formal training to get involved, method with repeated calculation obtains the result, visible so not high and complicated operation of the method degree of accuracy.

In order to obtain faint signal, the test macro that generally adopts mainly adopts floating-point modulus and time-varying program controlled amplifying technique at present, as the patent No. is 96212322.6, patent name is the Chinese utility model patent of floating-point formula nondestructive testing instrument for pile foundation, small-signal is amplified with bigger multiplication factor automatically, but the defective of this technology maximum is also to have amplified the signal of noise in amplifying signal, just powerless to small-signal less than noise signal, and the extraction of the collection of these data and the useful information key of test analysis often, if the information of extracting is not enough or be mixed with noise, best calculating, analytical method is also of no avail.

(3) summary of the invention

For effectively denoising of detection method, the not high deficiency of the degree of accuracy that overcomes existing pile foundation, the invention provides a kind of dynamic testing method that can effectively remove noise, basic structure testing signal that accuracy in detection is high.

The technical solution adopted for the present invention to solve the technical problems is:

A kind of dynamic testing method of basic structure testing signal, described method may further comprise the steps:

(1), at the monosymmetric sensor installation of the stake following pile body in top to be measured;

(2), when detecting, pounding with a hammer at the top of pile foundation produces a signal;

(3), the signal that receives of sensor record;

(4), the signal of two sensors is transferred to the signal smoothing module, two signals handled and merged according to the amplitude harmony time difference, and the HFS of signal is carried out curve smoothing;

(5), by low pass filter signal is carried out denoising;

(6), the signal after the noise abatement is transferred to signal processing module, carry out the integrity analysis of pile foundation according to the signal that obtains.

Further, in described (3), two sensor while received signal ripples, the formula of waveform signal is (1): x (t ₁)=f (t ₁)+n ₁(t), y (t ₂)=f (t ₂)+n ₂(t) (1); In described (4), calculate the Mintrop wave amplitude A of two signal waves ₁, A ₂With Mintrop wave sound duration t ₁, t ₂, calculate amplitude ratio Δ A=A ₁/ A ₂Harmony time difference Δ t=t ₁-t ₂, obtain two signals (2):

$x\left(t_1\right)=f\left(t_1\right)+n_1\left(t\right),y\left(t_1\right)=\frac{A_1}{\mathrm{\ΔA}}f(t_1-\mathrm{\Δt})+n_2\left(t\right)---\left(2\right);$

Be the Mintrop wave amplitude after handling by two signals being carried out the addition processing and getting Mintrop wave average, the signal wave after obtaining merging, the formula of Mintrop wave amplitude are (3):

$k\left(t_1\right)=\frac{1}{2}[f\left(t_1\right)+\frac{A_1}{\mathrm{\ΔA}}f(t_1-\mathrm{\Δt})+n_1\left(t\right)+n_2\left(t\right)]---\left(3\right).$

Further again, in described (4), utilize FFT that the HFS of signal is carried out curve smoothing.

Operating principle of the present invention is: the signal of two sensors is handled and is merged, and has improved the frequency of noise by merging, then high-frequency noise is carried out smoothly, obtains the test signal curve after the denoising at last.

Suppose that non-harmonic signal y (t) is got through time-delay by x (t), make y (t)=x (t-Δ t), then its cross-correlation function is (4):

$R_{\mathrm{xy}}\left(\mathrm{\τ}\right)=\underset{T\→\∞}{\lim }\frac{1}{T}{\∫}_0^{T}x\left(t\right)y(t-\mathrm{\Δt}+\mathrm{\τ})\mathrm{dt}---\left(4\right)$

As seen when τ=Δ t, the complete linear positive of two signals is relevant, and correlation function is got maximum value, that is to say, this two pairing times of signal cross-correlation function peak point are the time delay time between two signals, and this measurement of correlation is called time difference measurement of correlation.Therefore in measurement, analyze two signal: x (t)=f (the t)+n that obtains ₁(t), y (t)=f (t-Δ t)+n ₂(t), wherein Δ t represents two time differences between signal, n ₁(t), n ₂(t) expression noise.

Because the factor of sensor itself, the quantification that vibration is converted into charge signal there are differences, therefore the R1 that receives and the waveforms amplitude of R2 signal there are differences, but because be reception to same signal wave, do not consider that there is proportionate relationship in both under the situation of noise on the amplitude of waveform.Because two sensors life period on the received signal ripple is poor, can establishes Δ t and represent two time differences between signal simultaneously, if therefore do not consider that noise carries out time difference displacement to a signal and can obtain another signal.

After signal after being combined carries out smoothing processing, LPF is adopted in the filtering of signal, calculate cut-off frequency, the noise signal that will be higher than cut-off frequency is removed.At first signal is carried out Fourier transform and obtain the FFT frequency spectrum, calculate then according to formula (5) and ask cut-off frequency

$\mathrm{FC}=10\×\frac{1}{T}---\left(5\right)$

Length of field when wherein, T is.The signal pattern time domain that we gather is a wavelength, can try to achieve cut-off frequency according to this.Through low-pass filtering treatment, the composition that frequency is higher than cut-off frequency in signal is removed, the signal wave after the acquisition smoothing processing, thus conduct is to the reliable basis of the structure detection of pile foundation.

Utilize FFT to the principle that the HFS of signal carries out curve smoothing to be: the basic representation of Fourier transform is:

$X\left(k\right)=\underset{n=0}{\overset{N-1}{\mathrm{\Σ}}}x\left(n\right)W_{\frac{\mathrm{nk}}{N}},(k=\mathrm{0,1},\·\·\·N-1)---\left(6\right)$

$W_N^{\mathrm{nk}}=\exp [-\frac{2\mathrm{\πkn}}{N}]---\left(7\right)$

X (n) in the formula (6) (n=0,1 ... N-1) being that row are long is the output sequence of N, promptly passes through the data on the frequency domain behind the Fourier transform.For the signal after the digitlization, x (n) is one group of discrete real number signal, and X (k) is divided into real part x (v) with imaginary part y (v) two parts.X (v) and y (v) can form again amplitude A (v) with phase place P (v):

$A\left(v\right)=\sqrt{x^2\left(v\right)+y^2\left(v\right)}---\left(8\right)$

$P\left(v\right)=\arctan \frac{y\left(v\right)}{x\left(v\right)}---\left(9\right)$

And A (v) and P (the information that had both contained echo signal v), the information that also contains noise, if the regional portion at both places together, then can go out noise information by Fourier transform analysis, it is removed from the signal of catching, thereby reach the purpose of noise smoothing, obtain the echo signal of high s/n ratio.The essence of FFT is the weight function of utilizing in the formula (6)

Symmetry and periodically, DFT carries out a series of decomposition and combination the N point, makes the computational process of whole DFT become the series of iterations calculating process, and the operand of DFT is simplified greatly, makes that the detection of signal can be fast rapid.

Beneficial effect of the present invention mainly shows: 1, can effectively remove noise; 2, accuracy in detection height.

(4) specific embodiment

Below the present invention is further described.

A kind of dynamic testing method of basic structure testing signal, described method may further comprise the steps:

(1), at the monosymmetric sensor installation of the stake following pile body in top to be measured;

(2), when detecting, pounding with a hammer at the top of pile foundation produces a signal;

(3), the signal that receives of sensor record;

(4), the signal of two sensors is transferred to the signal smoothing module, two signals handled and merged according to the amplitude harmony time difference, and the HFS of signal is carried out curve smoothing;

(5), by low pass filter signal is carried out denoising;

(6), the signal after the noise abatement is transferred to signal processing module, carry out the integrity analysis of pile foundation according to the signal that obtains.

Further, in described (3), two sensor while received signal ripples, the formula of waveform signal is (1): x (t ₁)=f (t ₁)+n ₁(t), y (t ₂)=f (t ₂)+n ₂(t) (1); In described (4), calculate the Mintrop wave amplitude A of two signal waves ₁, A ₂With Mintrop wave sound duration t ₁, t ₂, calculate amplitude ratio Δ A=A ₁/ A ₂Harmony time difference Δ t=t ₁-t ₂, obtain two signals (2):

$x\left(t_1\right)=f\left(t_1\right)+n_1\left(t\right),y\left(t_1\right)=\frac{A_1}{\mathrm{\ΔA}}f(t_1-\mathrm{\Δt})+n_2\left(t\right)---\left(2\right);$

Be the Mintrop wave amplitude after handling by two signals being carried out the addition processing and getting Mintrop wave average, the signal wave after obtaining merging, the formula of Mintrop wave amplitude are (3):

$k\left(t_1\right)=\frac{1}{2}[f\left(t_1\right)+\frac{A_1}{\mathrm{\ΔA}}f(t_1-\mathrm{\Δt})+n_1\left(t\right)+n_2\left(t\right)]---\left(3\right).$

The detection of employing binary channels is not subjected to the variation of hammer vibration energy and exerts an influence.If certain is put under the effect of a certain hammer vibration energy Q, two sensor signal R ₁And R ₂The Mintrop wave amplitude be respectively A ₁And A ₂, this moment Δ A=A ₁/ A ₂If variation has taken place hammer vibration energy, the first amplitude that two sensors are received has changed a respectively ₁And a ₂Doubly, i.e. A ₁'=a ₁A ₁, A ₂'=a ₂A ₂Therefore the hammer vibration energy variation is essentially identical to the influence of two signals, at this moment Δ A '=a ₁A ₁/ a ₂A ₂≈ aA ₁/ aA ₂=A ₁/ A ₂=Δ A.

The time delay of signal can not influence detection yet, as R ₁And R ₂Sound duration change has taken place, changed Δ t ₁With Δ t ₂, because two signal transducers are fixed distance, so Δ t ₁≈ Δ t ₂=Δ t, so Δ t '=(t ₁+ Δ t)-(t ₂+ Δ t ₂) ≈ (t ₁+ Δ t)-(t ₂+ Δ t)=t ₁-t ₂=Δ t, therefore, Signal Processing still can keep accuracy.

The course of work of present embodiment is:

Adopt the binary channels detection technique, promptly by two sensors while received signal ripples, x (t ₁)=f (t ₁)+n ₁(t), y (t ₂)=f (t ₂)+n ₂(t), by calculating the Mintrop wave amplitude A of two signal waves ₁, A ₂With Mintrop wave sound duration t ₁, t ₂Calculate amplitude ratio Δ A=A ₁/ A ₂Harmony time difference Δ t=t ₁-t ₂, therefore can obtain two signal x (t ₁)=f (t ₁)+n ₁(t), $y\left(t_1\right)=\frac{A_1}{\mathrm{\ΔA}}f(t_1-\mathrm{\Δt})+n_2\left(t\right).$ Be the Mintrop wave amplitude after handling by two signals being carried out the addition processing and getting Mintrop wave average $k\left(t_1\right)=\frac{1}{2}[f\left(t_1\right)+\frac{A_1}{\mathrm{\ΔA}}f(t_1-\mathrm{\Δt})+n_1\left(t\right)+n_2\left(t\right)],$ Signal wave after merge.

Compare down, noise belongs to the HFS in the signal, and owing to the scrambling and the no correlation of noise, the merging of two signals makes the noise in the combined signal be in addition $n\left(t\right)=\frac{1}{2}[n_1\left(t\right)+n_2\left(t\right)],,$ The frequency of the frequency ratio original signal of noise is bigger in the combined signal.Therefore can make the frequency that improves noise by merging to handle, and signal itself is unaffected, therefore, if the HFS in the signal is carried out smoothly, just can effectively remove signal noise.

After using FFT to carry out signal level and smooth, signal is adopted LPF, calculate cut-off frequency, the noise signal that will be higher than cut-off frequency is removed.Obtain the signal wave after the smoothing processing,, and carry out the integrity analysis of pile foundation according to signal as reliable basis to the structure detection of pile foundation.

Claims (3)

1, a kind of dynamic testing method of basic structure testing signal, described method may further comprise the steps:

(1), at the monosymmetric sensor installation of the stake following pile body in top to be measured;

(2), when detecting, pounding with a hammer at the top of pile foundation produces a signal;

(3), the signal that receives of sensor record;

(4), the signal of two sensors is transferred to the signal smoothing module, two signals handled and merged according to the amplitude harmony time difference, and the HFS of signal is carried out curve smoothing;

(5), by low pass filter signal is carried out denoising;

(6), the signal after the noise abatement is transferred to signal processing module, carry out the integrity analysis of pile foundation according to the signal that obtains.

2, the dynamic testing method of a kind of basic structure testing signal as claimed in claim 1 is characterized in that:

In described (3), two sensor while received signal ripples, the formula of waveform signal is (1):

x(t ₁)＝f(t ₁)+n ₁(t)，y(t ₂)＝f(t ₂)+n ₂(t) (1)；

In described (4), calculate the Mintrop wave amplitude A of two signal waves ₁, A ₂With Mintrop wave sound duration t ₁, t ₂, calculate amplitude ratio Δ A=A ₁/ A ₂Harmony time difference Δ t=t ₁-t ₂, obtain two signals (2):

$x\left({\text{t}}_1\right)=f\left(t_1\right)+n_1\left(t\right),y\left(t_1\right)=\frac{A_1}{\mathrm{\ΔA}}f(t_1-\mathrm{\Δt})+n_2\left(t\right)---\left(2\right);$

Be the Mintrop wave amplitude after handling by two signals being carried out the addition processing and getting Mintrop wave average, the signal wave after obtaining merging, the formula of Mintrop wave amplitude are (3):

$k\left(t_1\right)=\frac{1}{2}[f\left(t_1\right)+\frac{A_1}{\mathrm{\ΔA}}f(t_1-\mathrm{\Δt})+n_1\left(t\right)+n_2\left(t\right)]---\left(3\right).$

3, the dynamic testing method of a kind of basic structure testing signal as claimed in claim 1 or 2 is characterized in that: in described (4), utilize FFT that the HFS of signal is carried out curve smoothing.