CN102141542B - System and method for elastic wave computed tomography (CT) test of concrete dam based on wireless sensor network - Google Patents

Abstract

The invention relates to the technical field of non-destructive testing of water conservancy projects, and aims to provide a concrete dam elastic wave CT testing system and method based on a wireless sensor network. The system includes an artificial vibration source module, a vibration signal acquisition module and a wireless sensor module. The vibration signal acquisition module includes a wireless sensor transmission component, a signal conditioner and a signal acquisition instrument respectively connected to the computer; the wireless sensor module is composed of multiple wireless sensor network nodes, each including: a three-component acceleration sensor connected to the control unit, a GPS One-machine multi-antenna positioning component and wireless sensor transmission component; GPS one-machine multi-antenna positioning component is set in the artificial vibration source module or vibration signal acquisition module. The invention has high test safety, easy operation of vibration source excitation, more accurate and intelligent measuring point positioning, avoids a large number of connection operations during on-site testing, and can realize "one send and more receive" in the test process, which can greatly improve the test performance. efficiency.

Description

Elastic wave CT testing system and method for concrete dam based on wireless sensor network

technical field

The invention belongs to the technical field of non-destructive testing of water conservancy projects, and in particular relates to an intelligent elastic wave CT testing method and system suitable for non-destructive testing of large-volume concrete dams.

Background technique

Since the first medical CT machine was successfully developed in 1971, CT technology has been widely used in industry, geophysics and other fields. In recent years, elastic wave CT technology has been introduced into the field of concrete dam safety detection. The main technical points of elastic wave CT imaging include forward modeling and inversion. As far as its imaging calculation method is concerned, the image reconstruction technology based on ray theory has been relatively mature, and the image reconstruction technology based on wave equation has gradually begun to be applied. However, compared with the great progress made in elastic wave CT calculation methods, elastic wave CT testing technology is relatively lagging behind, especially for large-volume structures like dams, the low efficiency of existing CT testing technology greatly restricts elastic The main problems in the development of wave CT are:

(1) The vibration source control is inconvenient. Conventional ultrasonic emission sources can only be used for testing small concrete components within 1 to 2 meters in size. Due to the large volume of the concrete dam, in the absence of a high-precision and high-sensitivity test system, a very large amount of energy is required to generate an excitation vibration signal for the dam. The current conventional artificial excitation vibration sources include: explosives, electric spark vibration sources, giant magnetostrictive acoustic wave emission vibration sources, etc. Among them, explosives and electric sparks have high energy, but on-site operation is not convenient enough, and explosives explosion or electric spark discharge operations will cause secondary hazards such as vibration, impact, and noise to the surrounding environment; especially dam CT requires many data sampling , The cost of explosives and electric sparks is relatively high, and the environment is not friendly enough. The giant magnetostrictive acoustic wave emission source is generally only suitable for acoustic wave testing within a few meters, and cannot be used for CT testing of concrete dams of tens of meters or even hundreds of meters.

(2) The positioning of the measuring points is inconvenient. In order to carry out dam CT testing, it is necessary to accurately locate the emission and reception points of elastic waves. However, due to the complex geometric shape of the dam, for example, the arch dam is a complex spatial surface structure, it is time-consuming and labor-intensive to use the total station measurement technology to locate the measurement points at the test site, and the accuracy is difficult to guarantee, which greatly restricts the acquisition of elastic wave CT data s efficiency.

(3) The host computer and the sensor of the existing elastic wave test system are electrically connected by data lines. When conducting CT tests on dams, due to the large size of the dam body, a long connection line is required, which makes the on-site test operation inconvenient. , and the length of the data line also reduces the efficiency of data transmission and reduces the overall reliability of the system.

(4) From the point of view of the test method, due to the limitation of the data acquisition mode of the existing test system, the CT test of the dam is often performed in the "one send and one receive" type, that is, one excitation point emits elastic waves, and one The receiving sensor receives. When performing elastic wave coverage scanning tests on dams, it is often necessary to conduct dozens to hundreds of sending and receiving tests, and the "one send, one receive" method is bound to be very inefficient.

In summary, the existing elastic wave CT testing system is only suitable for small-volume components, not for large-volume structures like dams; Existing testing systems have problems such as inconvenient operation and low efficiency, so it is urgent to develop new testing systems.

Contents of the invention

The technical problem to be solved by the present invention is to overcome the deficiencies in the prior art and provide a novel, intelligent CT test system for dams. The main test task of the test system is to record several groups of emitted vibration source signals and The received vibration signal at each measuring point position records the spatial coordinate position of the artificial vibration source point and the receiving measuring point. After obtaining these test data, the elastic wave travel time between the various spatial measuring points of the concrete dam can be calculated, and the elastic wave tomography of the dam body can be carried out after the forward and inverse calculation is carried out using the obtained elastic wave travel time data.

The purpose of the present invention is achieved through the following technical solutions:

Provide a kind of concrete dam elastic wave CT test system based on wireless sensor network, including artificial vibration source module, there is a force hammer for generating vibration excitation signal in this module, this system also includes vibration signal acquisition module and wireless sensor module;

The vibration signal acquisition module includes a wireless sensor transmission assembly, a signal conditioning instrument and a signal acquisition instrument connected to a computer respectively, and the wireless sensor transmission assembly, a signal conditioning instrument and a signal acquisition instrument are connected in sequence;

The wireless sensor module is composed of a plurality of wireless sensor network nodes, and each wireless sensor network node includes: a three-component acceleration sensor connected to the control unit, a GPS multi-antenna positioning component and a wireless sensor transmission component;

The system also includes a GPS one-machine multi-antenna positioning component arranged in the artificial vibration source module or the vibration signal acquisition module: if it is set in the artificial vibration source module, the hammer and the GPS one-machine multi-antenna positioning component are respectively connected to each other through the signal line. A wireless sensor transmission component is connected; if it is set in the vibration signal acquisition module, the component is directly connected with the computer, and the hammer is connected with the signal conditioner through the data line.

In the present invention, the vibration signal acquisition module and each wireless sensor network node include a power supply for supplying power to each working component.

In the present invention, the control unit of the wireless sensor network node is a single-chip microcomputer control unit.

As a further object of the invention, there is also provided a concrete dam elastic wave CT testing method based on the foregoing system, comprising the following steps:

(1) Arrange wireless sensor network nodes, artificial vibration source modules and vibration signal acquisition modules on the dam. The positions of wireless sensor nodes and artificial vibration source modules are determined according to the requirements and focus of the CT test section of the concrete dam. The vibration signal The acquisition module is adjacent to the artificial vibration source module;

(2) Conduct self-inspection of each instrument component before the dam CT test;

(3) Determine the spatial coordinate position of each wireless sensor network node and artificial vibration source module through the GPS one-machine multi-antenna positioning component, and store it in the computer;

(4) Vibration test is carried out on the artificial vibration source module, and the hammer is used to stimulate the vibration. The percussion force is determined according to the test distance. The principle of being able to excite clear vibration signals is the principle. The percussion force is determined through experiments from small to large;

(5) The excitation vibration signal of the artificial vibration source module is directly transmitted to the signal acquisition module through the data line connected to the hammer, or transmitted to the vibration signal acquisition module through the wireless sensor transmission component;

(6) While the artificial vibration source module is exciting the vibration, the vibration signal propagates to the surroundings through the concrete dam body. When it propagates to the pre-arranged wireless sensor nodes, the vibration signal is picked up by the three-component acceleration sensor, and the Send back the vibration signal acquisition module to realize "one send and more receive" collection;

(7) Import the position information of the vibration source and the acceleration sensor, and the elastic wave travel time test data between the vibration source and the acceleration sensor into the elastic wave CT calculation software built in the computer, and through forward and inverse iterative calculations, the concrete can be obtained Elastic wave CT image of the dam.

In the present invention, the vibration signal filtering processing step is also included: using the low-pass filtering function of the signal conditioner to filter the high-frequency part, and remove the high-frequency components of the vibration response of the concrete dam body excited by the pulse force.

In the present invention, the step of amplifying the vibration signal is also included: using the charge or voltage amplification function of the signal conditioner to amplify the collected weak vibration signal, so as to facilitate effective identification and quantitative analysis of the signal.

The beneficial effects of the present invention are:

(1) This test system abandons the traditional electric spark and explosive vibration source, greatly improving the safety of on-site testing, the vibration source excitation is easy to operate, and has no adverse effects on the environment;

(2) The positioning of measuring points is more accurate and intelligent, without on-site measurement operations, and the coordinates of all measuring points can be automatically recorded and stored;

(3) After adopting the wireless sensor network, a large number of connection operations during on-site testing are avoided, and the test data transmission is more convenient and reliable;

(4) After adopting the wireless sensor network, a major change in the data transmission mode has been realized, which can realize "one send and more receive" in the test process, which can greatly improve the test efficiency.

Description of drawings

Figure 1 is the overall composition diagram of the test system;

Figure 2 is a schematic diagram of the artificial vibration source module;

Fig. 3 is the schematic diagram of vibration signal acquisition module;

Fig. 4 is wireless sensor network node;

Figure 5. Schematic diagram of dam CT testing; among them, 1 is the artificial vibration source module arranged on the upstream surface of the concrete dam crest, 2 is the vibration signal acquisition module connected with the artificial vibration source module, and 3 is the artificial vibration source module arranged on the downstream surface of the concrete dam wireless sensor network nodes.

Detailed ways

First, confirm the technical terms mentioned in the present invention. The artificial vibration source module 1, the vibration signal acquisition module 2 and the wireless sensor module used in the present invention are all generalized functional modules. The hammer, signal conditioning instrument, signal acquisition instrument, computer, power supply, GPS multi-antenna positioning component, three-component acceleration sensor, wireless sensor transmission component, etc. among its components are all existing equipment that can be purchased directly on the market. Or it can be assembled and realized by those skilled in the art through conventional technical means, so the present invention will not repeat the details of its specific implementation.

The technical route of the present invention is: (1) Vibration excitation signals are generated by striking with a force hammer, and vibration signals on each measuring point are acquired by high-precision vibration data acquisition instruments. In order to obtain the weak vibration signal of the large-volume concrete structure, a signal conditioner is used to perform signal processing operations such as signal amplification, noise reduction, and filtering. (2) In order to solve the problem of inconvenient and low-precision positioning of on-site measuring points, GPS one-machine multi-antenna technology is used for precise positioning of all vibration measuring points. (3) The wireless sensor network technology is used to set the vibration sensor network, which avoids the cumbersome operation of on-site data connection, and realizes multi-channel and multi-path reliable transmission of data.

The main components of the test system of the present invention include: an artificial vibration source module 1, a vibration signal acquisition module 2 and a wireless sensor module. The artificial vibration source module 1 is mainly composed of a hammer and a data line. The vibration signal acquisition module 2 is composed of a signal conditioning instrument, a signal acquisition instrument, a computer, a power supply, a GPS multi-antenna positioning component, and a wireless sensor transmission component. The wireless sensor module is composed of multiple wireless sensor network nodes 3, and each wireless sensor network node 3 is composed of a high-sensitivity three-component acceleration sensor, a control unit, a GPS multi-antenna positioning component, a wireless sensor transmission component, and a power supply.

The composition of the system is shown in Figure 1. The artificial vibration source module 1 generates the vibration source signal for the dam CT test. On the one hand, the vibration source signal is transmitted to the signal acquisition module through the data line and recorded and saved; After being received by multiple wireless sensor nodes at each measuring point, they are sent to the signal acquisition module in a wireless manner.

The artificial vibration source module 1 is shown in Figure 2, and the components and functions of each part are as follows: the hammer is connected to the signal conditioner in the signal acquisition module through the data line. When the concrete dam body is struck with a force hammer, the force hammer exerts vibration excitation on the concrete dam body (that is: artificial excitation source), and can transmit the artificial excitation vibration signal through the data line to the The signal acquisition module records and saves.

The vibration signal acquisition module 2 is shown in Figure 3. The components and functions of each part are as follows: the wireless sensor transmission component is connected to the signal conditioning instrument, the signal conditioning instrument is connected to the signal acquisition instrument, and the test signal processed by the signal conditioning instrument can be stored and displayed on the computer. The power supply provides power to the components of this module. The main function of the signal conditioner is to realize the charge amplification, voltage amplification, analog integration, noise reduction, filtering and other processing of the original test signal. The main function of the signal acquisition instrument is to realize multi-channel synchronous acquisition, AD conversion, program-controlled amplification, etc. The computer can set the relevant parameters of the signal conditioning instrument and the signal acquisition instrument, and carry out the file operation of the test signal. The main function of the wireless sensor transmission component is to realize two-way communication and data transmission between the signal acquisition module and the wireless sensor module; Acquisition instructions, etc.; on the other hand, the vibration signal detected by the wireless sensor module is received by the wireless sensor transmission component after being sent wirelessly, and stored or displayed by the computer after passing through the signal conditioner and the signal collector. Generally, the artificial excitation signal generated by the hammer knocking is very weak, but after filtering, noise reduction, amplification and other processing by the signal conditioner and signal acquisition instrument, the original very weak vibration can be effectively picked up and distinguished in this test system Signal, so that the test accuracy and sensitivity are greatly improved.

The wireless sensor module is shown in Figure 4. According to the size of the test scale, there can be multiple wireless sensor network nodes 3. The composition and functions of each node are as follows: the single-chip control unit is used for communication control and parameter setting of each component of the module. Operation, temporary storage of test data, etc. The high-sensitivity three-component acceleration sensor is used to pick up the vibration signal of the measuring point. The wireless sensor transmission component is used to transmit the picked-up vibration signal to the signal acquisition module in a wireless manner. The GPS one-machine multi-antenna positioning component is used to determine the spatial position of the three-component acceleration sensor. The power supply provides electric energy for the wireless sensor module.

The implementation schematic diagram of the dam CT test using the concrete dam elastic wave CT test system based on the wireless sensor network is shown in Figure 5. The artificial vibration source module 1 and the vibration signal acquisition module 2 are connected by a data line, and the vibration signal acquisition module 2 communicates with multiple wireless sensor network nodes 3 through a wireless network.

Dam CT test steps are as follows:

(1) First, arrange the wireless sensor network nodes 3 and the artificial vibration source module 1 (vibration source excitation point) on the dam. The location of the wireless sensor network node 3 and the excitation point of the artificial vibration source is mainly determined according to the requirements and focus of the CT test section of the concrete dam. The vibration signal acquisition module 2 is generally in an adjacent position with the artificial vibration source module 1, as shown in Figure 2, its purpose is to locate the excitation point of the vibration source with the GPS one-machine multi-antenna positioning component in the vibration signal acquisition module 2.

(2) Before carrying out the CT test of the dam, carry out the instrument self-inspection first. The inspection items include: check whether the force sensor of the hammer is reliably connected, and false vibration signals will be caused if the installation is not firm; check whether the components in the vibration signal acquisition module 2 are in the correct acquisition waiting state; Whether the component vibration acceleration sensor is reliably connected to the dam body and can receive vibration signals.

(3) Determine the spatial coordinate position of each wireless sensor network node 3 according to the GPS one-machine multi-antenna positioning component, and store it in the computer.

(4) Perform a vibration test. When hammer is used to excite vibration, the hammer should be stable and the landing point should be accurate. The knocking force can be determined according to the test distance. The principle of being able to excite clear vibration signals is the principle. The knocking force can be determined from small to large through experiments.

(5) The artificial excitation vibration signal is directly transmitted to the vibration signal acquisition module 2 through the data line connected to the hammer.

(6) At the same time as artificial excitation, the vibration signal of the vibration source propagates to the surroundings through the concrete dam body, and when it propagates to each pre-arranged wireless sensor network node 3, it is picked up by the three-component acceleration sensor. Using the wireless sensor network mode, the sensor terminal nodes and the aggregation nodes can automatically form a self-organizing, multi-hop network. While performing an artificial excitation vibration operation, multiple wireless sensor network nodes 3 can collect vibration signals and send It sends back the signal acquisition module to realize "one send, multiple receive" acquisition.

(7) Vibration signal filtering processing. After the concrete dam body is hammered (pulse force excitation), its vibration response will contain unnecessary high-frequency components in the analysis. These high-frequency components will cause folding distortion and increase the difficulty of post-processing analysis. In this system, the low-pass filter function of the signal conditioner is used to filter the high-frequency part.

(8) Vibration signal amplification processing. The vibration signal excited by the artificial hammer is very weak. The charge or voltage amplification function of the signal conditioner is used to amplify the collected weak vibration signal, so as to facilitate the effective identification and quantitative analysis of the signal.

(9) For dam elastic wave CT, the required test data are mainly the position information of the vibration source and the acceleration sensor, and the elastic wave travel time between the vibration source and the acceleration sensor. Import these test data into the elastic wave CT calculation software built in the computer, and after forward and inverse iterative calculations, the elastic wave CT map of the dam can be obtained.

Certainly, the present invention can also have another implementation mode: a GPS one machine multi-antenna positioning component is set in the artificial vibration source module 1 to locate the excitation point of the vibration source. At the same time, a wireless sensor transmission component is set in the artificial vibration source module 1 to transmit the GPS positioning data and the received excitation vibration signal to the wireless sensor transmission component of the vibration signal acquisition module 2 through the wireless communication network. At this time, the hammer and the GPS one-machine multi-antenna positioning assembly are respectively connected to the wireless sensor transmission assembly through signal lines, and the GPS one-machine multi-antenna positioning assembly in the vibration signal acquisition module 2 can be cancelled.

The advantage of this technical solution is that the vibration signal acquisition module 2 is separated from the artificial vibration source module 1, without data cable connection, the vibration source and signal acquisition module can be arranged more flexibly, or simply realize the long-distance reception of test data, avoiding the test process interfered by the external environment.

By adopting the test system of the present invention, it is possible to avoid relying on inconvenient excitation methods such as explosives and electric sparks, and instead use a lighter hammer for artificial excitation, which eliminates secondary hazards such as shock waves and noise; Data transmission avoids the cumbersome operation of laying out very long data lines in conventional methods; the test system of the present invention can realize the "one send and multiple receive" test, which greatly improves the efficiency of on-site data collection; The spatial positioning of the network greatly improves the test accuracy and significantly reduces the intensity of field measurement work. After using charge amplification and high-frequency filtering, the traditional data acquisition system can collect and identify weaker vibration signals, which expands the effective testing distance of elastic waves and is more suitable for large-volume structures like dams.

Claims (6)

1. based on the concrete dam elastic wave CT test macro of wireless sensor network, comprise artificial vibration source module, the one power hammer for generation of the vibrational excitation signal is arranged in this module, it is characterized in that this system is involving vibrations signal acquisition module and wireless sensor module also;

Described vibration signals collecting module comprises the wireless senser transmission assembly, signal condition instrument and the signal sampler that link to each other with computing machine respectively, and wireless senser transmission assembly, signal condition instrument are connected with signal sampler and are connected;

Described wireless sensor module is comprised of a plurality of wireless sensor network nodes, and each wireless sensor network node includes: the Three-component accelerometer that links to each other with control module respectively, GPS one many antennas of machine positioning component and wireless senser transmission assembly;

This system also comprises GPS one many antennas of the machine positioning component that is arranged in artificial vibration source module or the vibration signals collecting module: as be arranged in the artificial vibration source module, then power hammer and GPS one many antennas of machine positioning component join by signal wire and a wireless senser transmission assembly that is arranged in the artificial vibration source module respectively; As be arranged in the vibration signals collecting module, then this assembly directly links to each other with computing machine, and the power hammer is connected with the signal condition instrument through data line.

2. elastic wave CT test macro according to claim 1 is characterized in that, described vibration signals collecting module and each wireless sensor network node include for the power supply to each work package power supply.

3. elastic wave CT test macro according to claim 1 is characterized in that, the control module of described wireless sensor network node is the Single-chip Controlling unit.

4. based on the concrete dam elastic wave CT method of testing of the described system of claim 1, may further comprise the steps:

(1) with each wireless sensor network node, artificial vibration source module and vibration signals collecting module arrangement on dam, the position of wireless sensor network node and artificial vibration source module determines that according to requirement and the focal point of concrete dam CT test section the vibration signals collecting module is in the adjacent position with artificial vibration source module;

(2) before carrying out the dam CT test, each instrument component is carried out self check;

(3) determine separately corresponding wireless sensor network node and manually the volume coordinate position of vibration source module by each GPS one many antennas of machine positioning component, and be stored in computing machine;

(4) artificial vibration source module is carried out vibration-testing, and employing power hammer knocks excited vibration, and percussion power determines that according to the measuring distance size can encourage clear vibration signal as principle, percussion power is ascending to be determined by test;

(5) the excited vibration signal of artificial vibration source module directly transfers to signal acquisition module by the data line that is connected with the power hammer, or is passed to the vibration signals collecting module by the wireless senser transmission assembly;

When (6) artificial vibration source module is carried out excited vibration, vibration signal through concrete dam body to around propagate, when being transmitted to each wireless sensor network node of arranging in advance, pick up through Three-component accelerometer, collect vibration signal, and it is beamed back the vibration signals collecting module, realize that " multicast " gathers;

Test data imports the elastic wave CT software for calculation that is built in computing machine when (7) elastic wave between positional information, vibration source and the acceleration transducer of vibration source and acceleration transducer being walked, through just drilling and the inverting iterative computation, can obtain the elastic wave CT figure of concrete dam.

5. concrete dam elastic wave CT method of testing according to claim 4, it is characterized in that, the step processed of involving vibrations signal filtering also: utilize the low-pass filtering function of signal condition instrument to realize HFS filtering, remove the high frequency composition that concrete dam body is subjected to the response of surging force excited vibration.

6. concrete dam elastic wave CT method of testing according to claim 4, it is characterized in that, also the involving vibrations signal amplifies the step of processing: electric charge or the voltage amplification function of utilizing the signal condition instrument, realization is to the amplification of collection Vibration Signal in Frequency Domain, so that effective identification and the quantitative test of signal.

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