A SUPER-DYNAMIC DEFORMATION MEASUREMENT SYSTEM WITH LONG-TIME PARALLEL CONTINUOUS ACQUISITION |
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| Authors: | LI Shi-nian QI Wen-bo LIU Li-qiang |
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| Affiliation: | 1.State Key Laboratory of Earthquake Dynamics, Institute of Geology, China Earthquake Administration, Beijing 100029, China;2.General Prospecting Institute, China National Administration of Coal Geology, Beijing 100039, China |
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| Abstract: | In the simulation experiments of earthquakes in laboratory, the instability slip or rupture events are obtained through steady state loading to simulate earthquake processes. In the experiments, steady-state deformation and unstable sliding occur alternately. It is hard to determine the origin time and duration of the instability event of fault, and there may be many instability events in one experiment. Therefore, in order to ensure that sufficient data is obtained at the extremely short instability moment to analyze the mechanical process of the earthquake source, the data acquisition system is required to continuously collect data at high-speed from the beginning of the experiment until the end, and the lasting time can be more than ten hours, so it requires huge storage space. Although the upper frequency limit of the instability signal is unknown exactly, but the previous experiments have shown that the frequency of the signal will reach hundred to several kilohertz, so the sampling frequency of the data acquisition should be above megahertz. In this case of long-time continuous high-frequency data acquisition, it is still necessary to maintain a high signal-to-noise ratio. Furthermore, previous studies have proved that the source mechanics field has a complex spatial structure, which is difficult to describe with a few measuring points, and it is necessary to perform simultaneous measurements of the source mechanics field for dozens or more measuring points. The combination of long-term continuous recording, high-resolution high-frequency sampling and multi-point simultaneous measurement poses a huge challenge to the technical indicators of the observing system. With the method for composing distributed synchronous acquisition machine group by using multiple high-resolution high-frequency sampling computers, a super dynamic deformation measurement system of high signal-to-noise ratio, which features 64-channel, 16-bit resolution, 4MHz sampling frequency, and parallel continuous acquisition with tens of hours was developed. This system can realize the synchronous acquisition of various signals, such as strain, acoustic emission, electromagnetic waves and displacement, so it is convenient for analyzing the conversion relationship between various physical quantities. |
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| Keywords: | super-dynamic fault instability deformation field acoustic emission continuous synchronous measurement distributed parallel acquisition |
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