| Utilizing seismic wave to research the time-varying stress state of fault systems is one of the most important fields for seismologists. It supplies an impossible underlying way to predicting earthquakes, while impelling the application of geophysics.The change of the stress on rock leads to the variation of the wave passing through, which utilizing elastic wave detects the state of stress was based on. Amid parameters of elastic wave, the seismic wave velocity is easy to estimated while it can reach a high precision, nevertheless, high precision measurement of wave velocity need a high requirement in launch and accept instrument. In recent times lots of numerical results and experimental results show that:the polarization of Rayleigh wave maybe more sensitive than seismic velocity to the stress of rock. We try to realize the technology using Rayleigh wave to estimated stress change in lab so as to serve the observation to earth media, and we did work as follows.1. Utilizing the high-speed data acquisition card, We build a measuring system which is based on virtual instrument technology and with universalty. It was found that:(1) It got an eminent stability:We drive the system running smoothly nearly one year, and we found no damaged and missed record due to software problems. (2)The system can fit different situations such as exciting active resource in different scale and receiving with multichannel, it got an excellent universality. (3)Utilizing the high speed data acquisition card the system improves the trigger precision to improve the measuring precision.2. We research the sensitivity of Rayleigh wave polarization to stress of rock.:A laboratory experiment was conducted, in which repetitive ultrasonic were excited to pass through the marble then received by an three-component sensor, aiming to make full use of the wave to study the variation of Rayleigh Wave Polarization and Velocity of Different Seismic Phases with the State of Stress. It was found that: (1)The stress sensitivity of different seismic phases velocity is 10E-8/Pa, with a descending order:Rayleigh wave> S wave> P wave.(2)The larger the stress, the more intense the Rayleigh polarization is, and the changes are nonlinear.(3)The stress sensitivity of Rayleigh polarization is times greater than wave velocity.3.We try to use Rayleigh wave polarization to analyze the data of active source outdoors experiment in Yunnan province. We found that the polarization changes more sharply than velocity, while shows a diurnal fluctuation. |
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