The Analysis Of The Earth Channel Characteristic Under Low Frequency Elastic Waves

Low frequency through-the-earth communication is regarded as the most reliable expedient means, which attracts wide attention. However, through-the-earth communication is hard to implement because of the heterogeneity of the earth channel and the geographic and geomorphic conditions complexity, especially multipath effect. The analysis of the earth channel characteristic under low frequency elastic waves appears so significant. Based on the requirement of mining disaster relief communication systems for the earth channel, the low frequency elastic wave's transmission performance in the earth channel is annlysed.The geologic parameters, delamination, waveguide effect and piezoelectric effect of the earth channel are deeply researched. The lowpass filtering characteristic of the earth channel has filtering action on the elastic waves traveling through the earth. The wave equation of elastic waves and the reflection and transmission on the elastic boundary surface are adopted to analyze the transmission characteristic of the low frequency elastic wave through the earth channel in mining disaster relief through-the-earth communication systems.Five stratum medium model of the earth channel is established. Then transmission characteristic of amplitude attenuation and multipath of low frequency elastic waves in homogeneous and non-complete elastic medium are respectively analyzed by using theory of elastic waves and simplified Zoeppritz equations. The simulation tool mathematica is used to simulate the analysis results.Some preliminary conclusions are put forward through detailed discussion.Although it is too difficult to study transmission characters of low frequency elastic waves in the earth channel throughly, the conclusions of this thesis have some reference value to develop mining disaster relief communication system. The further research of the issue would promote establishment of mining disaster relief communication system.