Micro-seismic monitoring is based on acoustic emission and seismology, and has developed into a new high-tech monitoring technology. It monitors production by observing and analyzing small seismic events occurring in production activities. Geophysical techniques for the effects, and underground states of activities.
When the underground rock ruptures or moves due to human or natural factors, a weak seismic wave is generated and propagates to the surroundings by arranging multiple sets of detectors in the space around the rupture area and collecting microseismic data in real time. It is adopted the principle of vibration positioning can determine the location of the rupture and display it in three-dimensional space after data processing.
Microseisms refer to the process that one or more local sources in a rock body and other materials quickly release their energy in the form of normal elastic waves under the influence of external forces and temperature. Microseisms originate from cracks (faults) in the material ), the destruction of the interface in the rock layer, the fracture of the matrix or inclusions. The technique of using microseismic monitoring instruments to collect, record, and analyze microseismic signals, and infer and analyze the source characteristics based on this is called microseismic monitoring technology. Microseismic monitoring technology is developed on the basis of seismic monitoring technology. It is the same as seismic monitoring and acoustic emission monitoring technology in principle, and is based on the principle of sound and energy that breaks during the process of rock mass destruction. The relationship between earthquake, microseism and acoustic emission can be seen from the frequency range
Microseismic monitoring system
Hardware: mainly divided into three parts, namely sensors, data collector, time synchronization, data communication, server and other parts.
The sensor converts formation movement (formation velocity or acceleration) into a measurable electrical signal. Non-seismic sensors can also be used in the case of microseismic networks.
The data collector is responsible for converting analog electrical signals from sensors into digital signals. The data can be recorded continuously or in trigger mode, and trigger algorithm is used to determine whether the microseismic event data is recorded and transmitted
Microseismic data is transmitted simultaneously to a central computer or local disk for storage or processing. Microseismic system can adopt a variety of data communication means to adapt to different system environment needs.
The software of microseismic system consists of system configuration management software, microseismic waveform data processing software, microseismic event visualization and interpretation software, microseismic event real-time display software and so on.
Multi-channel microseismic monitoring system is usually fixed in the monitoring area in the form of array, which can realize all-weather real-time monitoring of microseismic events, which is an important feature of this technology. With the appearance of all-digital microseismic monitoring instrument, the real-time data transmission with computer is realized, and the deficiency of analog signal monitoring equipment in real-time monitoring and data storage is overcome, which makes the real-time monitoring and storage of monitoring signals more convenient.
2.Full-scale stereo monitoring
The multi-channel microseismic monitoring system is used to monitor the stability and safety of underground engineering, which breaks through the traditional monitoring mode of "point" or "line" in the sense of force (stress), displacement (strain).Monitoring of the spatial conceptual time process of the rock mass failure (crack) process within the excavation influence range. This method is easy to implement monitoring of non-accessible locations in conventional methods.
Multi-channel microseismic monitoring technology generally adopts multichannel with multi-sensor monitoring, which can achieve high-precision positioning of microseismic events according to the actual needs of the project. This spatial positioning function of microseismic technology is as important as its real-time monitoring feature, which greatly enhances the application value of microseismic monitoring technology. Since the real-time data transmission is realized with the terminal monitoring computer, the real-time monitoring can be compiled, based on the 3D software for spatial positioning analysis, and the visual programming technology can be used to realize the visual 3D display of the real-time monitoring data.
4.Fully digital data acquisition, storage and processing
The all-digital technology overcomes the shortcomings of analog signal system, makes computer monitoring possible, and is more convenient for data acquisition, processing and storage. Due to the large amount of data collected by the multi-channel monitoring system, the computer is needed to process the data in real time, and the data is saved, while the large capacity hard disk storage equipment, optical disk and other media provide the guarantee for the storage, long-term preservation and reading of the recorded data. The high-speed sampling of microseismic monitoring system and the full waveform display of P and S waves make the spectrum analysis and processing of microseismic signal more convenient.
5.Remote monitoring and remote transmission of information
Microseismic monitoring technology can prevent the monitoring personnel from directly contacting the dangerous monitoring area, improve the monitoring environment of the monitoring personnel, and also greatly reduce the labor intensity of monitoring. The emergence of digital technology and the development of optical fiber communication technology have made it possible to transmit data quickly and remotely. Digital optical fiber technology not only makes the signal transmission attenuation small, but also other electrical signals do not interfere with the optical signal, which can ensure the high-quality remote transmission of the monitoring signal in the complex underground environment. In addition, Internet technology and GPS technology can be used to transmit microseismic monitoring data to the world in real time to realize remote sharing of data.
6. Multi-user computer visual monitoring and analysis
The three-dimensional display of the monitoring process and results, as well as the remote transmission of the monitoring signals, the use of network technology (local area network) to achieve multi-user visual monitoring, that is, the monitoring terminal can be set up in the offices of the safety supervision departments and expert offices at all levels. Multi-expert real-time analysis and evaluation create conditions.