CN110988130A - A test system for damage identification in rock slope laboratory tests - Google Patents
A test system for damage identification in rock slope laboratory tests Download PDFInfo
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
- G01N29/04—Analysing solids
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- G01N29/07—Analysing solids by measuring propagation velocity or propagation time of acoustic waves
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
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Abstract
本发明涉及损伤识别测试技术领域，且公开了一种用于岩质斜坡室内试验损伤识别的测试系统，包括振动传感器、PVDF压电薄膜和加速度传感器，所述振动传感器、PVDF压电薄膜和加速度传感器的输出端均与数据采集系统的输入端电连接。该用于岩质斜坡室内试验损伤识别的测试系统，结合岩质斜坡室内物理模型试验，利用结构响应信号，在时域内对岩土结构进行损伤识别，利用对损伤敏感的能量指标，进行损伤定位，也可以大致反映损伤程度，并基于此建立岩质斜坡震裂损伤模型，对地震滑坡的科学研究起到一定的支撑作用，与现有技术相比准确性更高、应用范围更广，为达到这个优势，最重要的是损伤信号的识别、提取和分析，可靠性更高。
The invention relates to the technical field of damage identification test, and discloses a test system for damage identification of rock slope indoor test, comprising a vibration sensor, a PVDF piezoelectric film and an acceleration sensor, the vibration sensor, the PVDF piezoelectric film and the acceleration sensor The output ends of the sensors are all electrically connected with the input ends of the data acquisition system. The test system for damage identification of rock slope laboratory test, combined with the rock slope laboratory physical model test, uses the structural response signal to identify the damage of the geotechnical structure in the time domain, and uses the damage-sensitive energy index to locate the damage. , it can also roughly reflect the damage degree, and based on this, a rock slope shatter damage model is established, which plays a certain supporting role in the scientific research of earthquake landslides. Compared with the existing technology, it has higher accuracy and wider application range. To achieve this advantage, the most important thing is the identification, extraction and analysis of damage signals, which is more reliable.
Description
Technical Field
The invention relates to the technical field of damage identification testing, in particular to a testing system for rock slope indoor test damage identification.
Background
At present, a damage identification method based on vibration is mainly applied to the fields of machinery, civil engineering, aviation, oceans and the like, damage identification objects are mainly concrete structures and metal structures, a damage identification technical method and a device aiming at rock-soil body materials are relatively deficient, although the rock-soil body materials are greatly different from the metal and the concrete materials, the damage identification method and the theory are consistent, once the structure is damaged, physical parameters (such as rigidity, damping and the like) of the rock-soil body materials are inevitably changed, and the changes cause the change of structural response, so the damage identification method based on vibration can also be applied to the rock-soil body structures. The key is how to be able to accurately measure the response signals of the structure, how to extract information from these test data that reflects the characteristics of the structure, and use this information to identify structural damage.
The existing damage identification method based on vibration is mainly frequency domain, frequency domain parameters are obtained by analyzing dynamic test data of a structure, the indexes are directly used for identifying structural damage, or the indexes are combined with methods such as model correction and intelligent optimization to identify damage, but the damage identification method based on frequency has limitations, and damage identification by only using frequency information is unreliable, so that a test system for indoor test damage identification of a lithologic slope is provided to solve the problems.
Disclosure of Invention
Technical problem to be solved
Aiming at the defects of the prior art, the invention provides a test system for identifying the damage of an indoor test of a rock slope, which has the advantage of high accuracy and solves the problems that the existing damage identification method based on vibration is mainly frequency domain, frequency domain parameters are obtained by analyzing dynamic test data of a structure, the indexes are directly used for identifying the damage of the structure, or the indexes are combined with methods such as model correction, intelligent optimization and the like to identify the damage, but the damage identification method based on frequency has the limitation, and the damage identification by only using frequency information is unreliable.
(II) technical scheme
In order to achieve the purpose of high accuracy, the invention provides the following technical scheme: the utility model provides a test system for rock matter slope indoor test damage discernment, includes vibration sensor, PVDF piezoelectric film and acceleration sensor, vibration sensor, PVDF piezoelectric film and acceleration sensor's output all is connected with data acquisition system's input electricity, and data acquisition system's output is connected with microcomputer's input electricity.
Preferably, the data acquisition system comprises a signal generator and a filtering and amplifying circuit, the input end of the filtering and amplifying circuit is electrically connected with the output ends of the vibration sensor, the PVDF piezoelectric film and the acceleration sensor, the output end of the filtering and amplifying circuit is electrically connected with the input end of the multi-way switch, the output end of the multi-way switch is electrically connected with the input end of the A/D converter, the output end of the A/D converter is electrically connected with the input end of the interface circuit, the output end of the interface circuit is electrically connected with the input end of the control system, the output end of the control system is electrically connected with the input ends of the filtering and amplifying circuit and the multi-way switch, and the output end of the interface circuit is.
Preferably, the lesion identification can be divided into four steps: data acquisition → time-frequency joint analysis → characteristic parameter extraction → establishment of a damage identification method.
(III) advantageous effects
Compared with the prior art, the invention provides a test system for rock slope indoor test damage identification, which has the following beneficial effects:
this a test system for rock matter slope indoor test damage discernment, combine the indoor physical model experiment of rock matter slope, utilize structure response signal, damage discernment is carried out to the geotechnical structure in the time domain, utilize the energy index sensitive to the damage, carry out damage location, also can roughly reflect the damage degree, and establish rock matter slope shatter damage model based on this, play certain supporting role to the scientific research of earthquake landslide, it is higher to compare the accuracy with prior art, the range of application is wider, for reaching this advantage, most importantly damage signal's discernment, extract and analysis, the reliability is higher.
Drawings
FIG. 1 is a schematic block diagram of a testing system for rock slope indoor test damage identification according to the present invention;
fig. 2 is a testing flow chart of a testing system for rock slope indoor test damage identification according to the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Referring to fig. 1-2, a testing system for rock slope indoor test damage identification comprises a vibration sensor, a PVDF piezoelectric film and an acceleration sensor, wherein output ends of the vibration sensor, the PVDF piezoelectric film and the acceleration sensor are electrically connected with an input end of a data acquisition system, an output end of the data acquisition system is electrically connected with an input end of a microcomputer, the data acquisition system comprises a signal generator and a filtering and amplifying circuit, an input end of the filtering and amplifying circuit is electrically connected with output ends of the vibration sensor, the PVDF piezoelectric film and the acceleration sensor, an output end of the filtering and amplifying circuit is electrically connected with an input end of a multi-way switch, an output end of the multi-way switch is electrically connected with an input end of an a/D converter, an output end of the a/D converter is electrically connected with an input end of an interface circuit, and an output end of the interface circuit, the output end of the control system is electrically connected with the input ends of the filtering and amplifying circuit and the multi-way switch, the output end of the interface circuit is electrically connected with the input end of the microcomputer, and the damage identification can be divided into four steps: data acquisition → time-frequency joint analysis → characteristic parameter extraction → establishment of a damage identification method.
When the device is used, ultrasonic signals before and after rock slope damage in the test process are collected, noise is adaptively eliminated by using an unsteady signal processing analysis method (EMD and Hilbert-Huang transform), signal characteristic parameters strongly related to the slope damage are extracted and analyzed, time domain signal waveform characteristic parameter description (such as wave speed, wavelength, peak sum, energy and the like) and frequency domain characteristic parameter description (marginal spectrum peak value, kurtosis, skewness, attenuation, dominant frequency and the like) are introduced on the basis of the traditional event rate along with the statistical analysis of a loading path, and a correlation analysis model between the characteristic parameters and the slope shatter damage is established according to the ultrasonic signal waveform characteristic space-time dynamic evolution rule; identifying the occurrence and the damage degree of slope damage through the comparison of characteristic parameters before and after vibration; determining the position of the damage according to the distribution of the ultrasonic sensors; and constructing a technical method system for identifying the slope shatter damage.
To sum up, the test system for identifying the damage of the indoor test of the rocky slope combines the indoor physical model test of the rocky slope, utilizes the structural response signal to identify the damage of the rock-soil structure in the time domain, utilizes the energy index sensitive to the damage to position the damage, can also approximately reflect the damage degree, establishes the rocky slope shattering damage model based on the structural response signal, plays a certain supporting role in scientific research of earthquake landslide, has higher accuracy and wider application range compared with the prior art, and has the advantages of higher importance in identification, extraction and analysis of the damage signal and higher reliability, thereby solving the problems that the existing damage identification method based on vibration is mainly frequency domain, utilizes the dynamic test data analysis of the structure to obtain the parameters, and then directly utilizes the frequency domain indexes to identify the structural damage, or modifies the indexes and the model, Methods such as intelligent optimization and the like are combined to identify the damage, but the damage identification method based on frequency has limitations, and the problem that damage identification by simply using frequency information is unreliable is solved.
It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114187744A (en) * | 2021-12-06 | 2022-03-15 | 四川可易世界科技有限公司 | A kind of landslide debris flow monitoring and early warning method, equipment, system and medium |
| CN115586262A (en) * | 2022-03-29 | 2023-01-10 | 哈尔滨工业大学 | An online non-destructive monitoring method for micro-grinding based on acoustic emission technology |
Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101836100A (en) * | 2007-10-24 | 2010-09-15 | Abb研究有限公司 | Method for detecting and automatically identifying damage to rolling bearings |
| CN102043019A (en) * | 2010-10-21 | 2011-05-04 | 重庆大学 | Method for identifying damages of frame structure |
| CN102937646A (en) * | 2012-11-08 | 2013-02-20 | 沈阳建筑大学 | Health monitoring system for concrete structure |
| CN204116284U (en) * | 2014-10-27 | 2015-01-21 | 中国民航大学 | A kind of aircraft cellular structural composite material knocks and detects and non-destructive tests device |
| CN104634870A (en) * | 2014-12-24 | 2015-05-20 | 同济大学 | Tunnel structure damage identification device based on vibration response test |
| CN105510049A (en) * | 2015-12-23 | 2016-04-20 | 哈尔滨工业大学 | Vibration signal analysis-based vehicle operation condition monitoring module and method |
| CN108458858A (en) * | 2017-12-04 | 2018-08-28 | 嘉兴博感科技有限公司 | A kind of train coupler arranged structural healthy monitoring system |
| CN109115868A (en) * | 2018-09-29 | 2019-01-01 | 东北大学 | A kind of depth of defect detection device and method based on impulse eddy current |
-
2019
- 2019-12-18 CN CN201911312913.6A patent/CN110988130A/en active Pending
Patent Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101836100A (en) * | 2007-10-24 | 2010-09-15 | Abb研究有限公司 | Method for detecting and automatically identifying damage to rolling bearings |
| CN102043019A (en) * | 2010-10-21 | 2011-05-04 | 重庆大学 | Method for identifying damages of frame structure |
| CN102937646A (en) * | 2012-11-08 | 2013-02-20 | 沈阳建筑大学 | Health monitoring system for concrete structure |
| CN204116284U (en) * | 2014-10-27 | 2015-01-21 | 中国民航大学 | A kind of aircraft cellular structural composite material knocks and detects and non-destructive tests device |
| CN104634870A (en) * | 2014-12-24 | 2015-05-20 | 同济大学 | Tunnel structure damage identification device based on vibration response test |
| CN105510049A (en) * | 2015-12-23 | 2016-04-20 | 哈尔滨工业大学 | Vibration signal analysis-based vehicle operation condition monitoring module and method |
| CN108458858A (en) * | 2017-12-04 | 2018-08-28 | 嘉兴博感科技有限公司 | A kind of train coupler arranged structural healthy monitoring system |
| CN109115868A (en) * | 2018-09-29 | 2019-01-01 | 东北大学 | A kind of depth of defect detection device and method based on impulse eddy current |
Non-Patent Citations (3)
| Title |
|---|
| 于德介 等: ""Hilbert-Huang变换在齿轮故障诊断中的应用"", 《机械工程学报》 * |
| 刘珍: ""基于振动信号的结构模态参数识别与损伤分析"", 《中国优秀硕士学位论文全文数据库（电子期刊）》 * |
| 刘锡军: ""结构损伤综合诊断理论与试验研究"", 《中国博士学位论文全文数据库（电子期刊）》 * |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114187744A (en) * | 2021-12-06 | 2022-03-15 | 四川可易世界科技有限公司 | A kind of landslide debris flow monitoring and early warning method, equipment, system and medium |
| CN115586262A (en) * | 2022-03-29 | 2023-01-10 | 哈尔滨工业大学 | An online non-destructive monitoring method for micro-grinding based on acoustic emission technology |
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