CN101706334B - Method for performing non-destructive detection on service load of anchor bolt by using low-frequency guided wave - Google Patents

Method for performing non-destructive detection on service load of anchor bolt by using low-frequency guided wave Download PDF

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Publication number
CN101706334B
CN101706334B CN2009102384819A CN200910238481A CN101706334B CN 101706334 B CN101706334 B CN 101706334B CN 2009102384819 A CN2009102384819 A CN 2009102384819A CN 200910238481 A CN200910238481 A CN 200910238481A CN 101706334 B CN101706334 B CN 101706334B
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guided wave
frequency
anchor pole
anchor
operating load
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CN101706334A (en
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王成
何文
宁建国
唐永刚
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Beijing Institute of Technology BIT
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Beijing Institute of Technology BIT
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Abstract

The invention relates to a method for performing non-destructive detection on a service load of an anchor bolt by using low-frequency guided wave, which can detect the change of the service load of the anchor bolt on the spot, and belongs to the field of non-destructive detection. The method comprises the steps of: firstly, determining the propagation velocity of the guided wave in the free anchor bolt and the length of a free segment of the end anchor bolt; then determining the propagation velocity of the guided wave in the free segment of the end anchor bolt acted by a pre-tightening force; and finally, establishing a relation curve of the service load and the propagation time of the guided wave in the free segment of the end anchor bolt. On this basis, the service load can be determined by detecting a reflection echo of the guided wave on an upper interface of the anchoring segment of the end anchor bolt and the propagation time of the guided wave in the free segment. The method can detect the service load of the anchor bolt, can improve confidence level, and has the advantages of simplicity, strong operability and easy real-time monitoring.

Description

A kind of method of utilizing low-frequency guided wave the anchor pole operating load to be carried out Non-Destructive Testing
Technical field
The present invention relates to a kind of method of utilizing guided wave that the operating load of anchor pole is carried out Non-Destructive Testing, can the on-the-spot operating load that detects anchoring rod, belong to the Non-Destructive Testing field.
Background technology
Along with the extractive industry development, the stability problem of underground structure has caused people's attention day by day, research for the roadway surrounding rock Detection of Stability has developed into a new stage, and many proven technique have been arranged, such as the convergence displacement of surface, tunnel, dark basic point displacement measurement, surrounding rock loose circle theory and detection, these technology are obtaining application widely aspect the control of coal mine roadway stability of surrounding rock.But these researchs to the tunnel structure stability of surrounding rock are main means with the statics in the solid mechanics all, with surrouding rock deformation is main research object, Observations Means that is adopted and instrument and equipment are all based on static and quasi static test, there is hysteresis quality in this reaction stability of surrounding rock information that has just caused being obtained, has also just determined the stability of surrounding rock control measure made thus and the passivity of means.
Bolt supporting is extensively returned in the middle of the support system that is applied to roadway surrounding rock as a kind of active support form.The operating load of anchor pole is relevant with multiple factors such as the tectonic structure of country rock, cross dimensions, anchor pole arrangement parameter, and it is the key parameter that influences stability of surrounding rock.By detection to the anchor pole operating load, can grasp the mechanics of the core-surrouding rock stress of stability of surrounding rock control directly, in real time, thereby might be in roadway surrounding rock and supporting construction unstability thereof, collapse fall before, take effective reinforcement measure, thereby reach the purpose of ACTIVE CONTROL stability of surrounding rock.
In engineering reality, do not form the operating load that a kind of effective lossless detection method is measured anchoring rod as yet.Therefore, the operating load of anchor pole being carried out Non-Destructive Testing is to underground structural stability analysis problem demanding prompt solution.
Summary of the invention
The objective of the invention is problem, propose a kind of method of utilizing low-frequency guided wave the anchor pole operating load to be carried out Non-Destructive Testing for the operating load that solves effective measurement anchoring rod.Guided wave is very little along the travel path decay, can propagate distance very far away along member, can reach tens meters farthest.Low-frequency guided wave particularly changes responsively for the operating load of anchor pole, and the velocity of propagation of low-frequency guided wave in anchor pole be the linear decrease relation with operating load, and therefore, the low-frequency guided wave detection can be carried out reliable and effective detection to the operating load of anchor pole.
The technical solution adopted in the present invention is as follows:
Step 1, use the low-frequency guided wave signal, anchoring rod to be detected is detected, determine and clearly to receive anchor rod anchored section of end anchor and excite the guided wave frequency f when going up the interface reflection echo.The frequency range of low-frequency guided wave signal is greater than 0kHz, and smaller or equal to 300kHz.
Preferable, the frequency range of employed low-frequency guided wave signal is 20～100kHz.
Step 2, use the frequency determined through the step 1 guided wave that excites as f, detect another root free bolt with same batch of anchoring rod to be detected, that determines this frequency thus excites the velocity of propagation V of guided wave in this free bolt f
Step 3, use the frequency determined through step 1 the guided wave that excites,, anchoring rod to be detected is detected not applying under the operating load state as f.According to the travel-time t that excites guided wave in the free section of the end anchor anchor pole that does not apply operating load, reach the velocity of propagation V that determines through step 2 f, determine the free segment length L of end anchor anchor pole:
L＝(t×V f)/2
Because low-frequency guided wave is subjected to effect of the interface bigger when propagating in anchor pole, under specific frequency, can clearly obtain the reflection echo at guided wave interface on anchor rod anchored section of anchor of end, and record the travel-time of guided wave in the free section of end anchor anchor pole, both can try to achieve the length of holding the free section of anchor anchor pole with the velocity of propagation of low-frequency guided wave in free bolt.
Step 4, anchoring rod to be detected is applied pretightning force F ', its value is read by loading instrument, and according to the free segment length L of end anchor anchor pole that determines through step 3, and frequency is the travel-time Δ t of the guided wave of f free section of pretightning force effect end anchor anchor pole AB', determine the velocity of propagation V of this guided wave in the free section of pretightning force effect end anchor anchor pole f F':
V f F ′ = 2 ( 1 + F ′ πr 2 E ) L Δ t AB ′
In the following formula, E is the elastic modulus of anchor pole, and r is the radius of anchor pole.
Step 5, is at any time measured frequency and is the time Δ t that the guided wave of f is propagated in the free section of operating load F effect end anchor anchor pole AB, according to the result of aforementioned each step, determine the operating load of anchoring rod:
F = πr 2 EΔ t AB ( V f - 2 L Δt AB ) F ′ 2 LF ′ + πr 2 E Δt AB ( V f - V f F ′ )
So far, just finished the work that utilizes low-frequency guided wave the anchor pole operating load to be carried out Non-Destructive Testing.By detecting the travel-time of guided wave in the free section of end anchor anchor pole, variation that can monitoring load.
Beneficial effect
The present invention contrasts prior art, has the following advantages:
(1) MTD is big, is fit to detect the operating load of anchor pole in the engineering reality;
(2) accuracy of detection height, error can engineering demands;
(3) detection method is simple, and strong operability is easy to real-time monitoring;
(4) the detection cost is low.
Description of drawings
Fig. 1 is the schematic flow sheet of the inventive method;
Fig. 2 is measured waveform figure in the specific embodiment of the invention.
Embodiment
Below in conjunction with accompanying drawing and example the inventive method is described in further detail.
A kind of method of utilizing low-frequency guided wave that the anchor pole operating load is carried out Non-Destructive Testing, as shown in Figure 1, concrete implementation step is as follows:
Step 1, use the low-frequency guided wave signal of 20～100kHz scope, anchoring rod to be detected is detected, determine and clearly to receive anchor rod anchored section of end anchor and excite the guided wave frequency f when going up the interface reflection echo.Fig. 2 detects the time domain waveform figure of anchoring rod for using guided wave, and A is the excitation wave peak point, and B is guided wave reflection echo peak point in interface on anchoring section, Δ t ABReflection echo and the mistiming that excites guided wave for guided wave interface on anchoring section.
Step 2, use the frequency determined through the step 1 guided wave that excites as f, detect another root free bolt with same batch of anchoring rod to be detected, that determines this frequency thus excites the velocity of propagation V of guided wave in this free bolt f
Step 3, use the frequency determined through step 1 the guided wave that excites,, anchoring rod to be detected is detected not applying under the operating load state as f.According to the travel-time t that excites guided wave in the free section of the end anchor anchor pole that does not apply operating load, reach the velocity of propagation V that determines through step 2 f, determine the free segment length L of end anchor anchor pole:
L＝(t×V f)/2
Step 4, anchoring rod to be detected is applied pretightning force F ', its value is read by loading instrument, and according to the free segment length L of end anchor anchor pole that determines through step 3, and frequency is the travel-time Δ t of the guided wave of f free section of pretightning force effect end anchor anchor pole AB', determine the velocity of propagation V of this guided wave in the free section of pretightning force effect end anchor anchor pole f F':
V f F ′ = 2 ( 1 + F ′ πr 2 E ) L Δ t AB ′
In the following formula, E is the elastic modulus of anchor pole, and r is the radius of anchor pole.
Step 5, is at any time measured frequency and is the time Δ t that the guided wave of f is propagated in the free section of operating load F effect end anchor anchor pole AB, according to the result of aforementioned each step, determine the operating load of anchoring rod:
F = πr 2 EΔ t AB ( V f - 2 L Δt AB ) F ′ 2 LF ′ + πr 2 E Δt AB ( V f - V f F ′ )
So far, just finished the work that utilizes low-frequency guided wave the anchor pole operating load to be carried out Non-Destructive Testing.
Below by embodiment the inventive method is described.
Use 20～100kHz frequency guided wave, treat test side anchor anchor pole and detect, the radius of anchor pole is 20mm, and elastic modulus E is 210e9Pa.By test waveform, determine that 50kHz and 60kHz guided wave have obvious echoed signal in the interface on the anchor rod anchored end of end anchor, use the operating load of these two kinds of frequency guided wave signals test side anchor anchor poles below.
Embodiment 1
Frequency of utilization is that the guided wave that excites of 50kHz detects a free bolt, records V f=5010.4m/s, recording frequency according to step 3 is the travel-time t=3.992e-4s of 50kHz guided wave in the free section of the end anchor anchor pole that does not apply operating load, determines the free segment length L=1m of end anchor anchor pole then.Anchoring rod to be detected is applied pretightning force F '=40kN, and this guided wave is at the travel-time Δ t of the free section of pretightning force effect end anchor anchor pole AB'=3.995e-4s then obtains the velocity of propagation V of this guided wave in the free section of pretightning force effect end anchor anchor pole by step 4 f F'=5008.8m/s. measures the time Δ t that this guided wave is propagated in the free section of operating load F effect end anchor anchor pole AB=4.001e-4 calculate operating load F=100.628kN by step 5, and the actual value of operating load is 100kN, and error only is 0.628%.
Embodiment 2
Frequency of utilization is that the guided wave that excites of 60kHz detects a free bolt, records V f=4936m/s, recording frequency according to step 3 is the travel-time t=4.051e-4s of 60kHz guided wave in the free section of the end anchor anchor pole that does not apply operating load, determines the free segment length L=1m of end anchor anchor pole then.Anchoring rod to be detected is applied pretightning force F '=40kN, and this guided wave is at the travel-time Δ t of the free section of pretightning force effect end anchor anchor pole AB'=4.055e-4s then obtains the velocity of propagation V of this guided wave in the free section of pretightning force effect end anchor anchor pole by step 4 f F'=4934.4m/s.Measure the time Δ t that this guided wave is propagated in the free section of operating load F effect end anchor anchor pole AB=4.0615e-4s calculate operating load F=102.2kN by step 5, and the actual value of operating load is 100kN, and error only is 2.2%.

Claims (2)

1. one kind is utilized low-frequency guided wave to the method that the anchor pole operating load carries out Non-Destructive Testing, it is characterized in that may further comprise the steps:
Step 1, use the low-frequency guided wave signal, anchoring rod to be detected is detected, determine and clearly to receive anchor rod anchored section of end anchor and excite the guided wave frequency f when going up the interface reflection echo;
The frequency range of low-frequency guided wave signal is greater than 0kHz, and smaller or equal to 300kHz;
Step 2, use the frequency determined through the step 1 guided wave that excites as f, detect another root free bolt with same batch of anchoring rod to be detected, that determines this frequency thus excites the velocity of propagation V of guided wave in this free bolt f
Step 3, use the frequency determined through step 1 the guided wave that excites as f, do not applying under the operating load state, anchoring rod to be detected is detected,, reach the velocity of propagation V that determines through step 2 according to the travel-time t that excites guided wave in the free section of the end anchor anchor pole that does not apply operating load f, determine the free segment length L of end anchor anchor pole:
L＝(t×V f)/2
Step 4, anchoring rod to be detected is applied pretightning force F ', its value is read by loading instrument, and according to the free segment length L of end anchor anchor pole that determines through step 3, and frequency is the travel-time Δ t of the guided wave of f in pretightning force F ' effect end anchor anchor pole freedom section AB', determine the velocity of propagation V of this guided wave in the free section of pretightning force F ' effect end anchor anchor pole f F':
V f F ′ = 2 ( 1 + F ′ πr 2 E ) L Δ t AB ′
In the following formula, E is the elastic modulus of anchor pole, and r is the radius of anchor pole;
Step 5, low-frequency guided wave velocity of propagation and the operating load in anchor pole is the linear decrease relation, and at any time, measuring frequency is the time Δ t of the guided wave of f in the free section propagation of operating load F effect end anchor anchor pole AB, according to the result of aforementioned each step, determine the operating load of anchoring rod:
F = πr 2 EΔ t AB ( V f - 2 L Δt AB ) F ′ 2 LF ′ + πr 2 E Δt AB ( V f - V f F ′ ) .
2. a kind of low-frequency guided wave that utilizes as claimed in claim 1 is characterized in that to the method that the anchor pole operating load carries out Non-Destructive Testing the frequency range of employed low-frequency guided wave signal is 20～100kHz in the step 1.
CN2009102384819A 2009-11-20 2009-11-20 Method for performing non-destructive detection on service load of anchor bolt by using low-frequency guided wave Expired - Fee Related CN101706334B (en)

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CN108917998A (en) * 2018-08-24 2018-11-30 河南理工大学 A kind of monitoring method and system using ultrasonic echo monitoring surrouding rock stress state

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101082564A (en) * 2006-06-01 2007-12-05 中国矿业大学 Stochastic nondestructive power detecting technology for detecting anchor rod pressure state
CN201202484Y (en) * 2008-06-06 2009-03-04 何文飞 Anchor rod
CN101458232A (en) * 2009-01-09 2009-06-17 北京理工大学 Anchor rod anchoring quality detecting instrument

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101082564A (en) * 2006-06-01 2007-12-05 中国矿业大学 Stochastic nondestructive power detecting technology for detecting anchor rod pressure state
CN201202484Y (en) * 2008-06-06 2009-03-04 何文飞 Anchor rod
CN101458232A (en) * 2009-01-09 2009-06-17 北京理工大学 Anchor rod anchoring quality detecting instrument

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
何文,王成,宁建国,唐永刚.导波在端锚锚杆锚固段上界面的反射研究.《煤炭学报》.2009,第34卷(第11期),第1451-1455页. *

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