Multichannel transient Rayleigh wave detection method

Abstract

The invention relates to the engineering geological investigation field, in particular to a multichannel transient Rayleigh wave detection method. The multichannel transient Rayleigh wave detection method includes steps: obtaining arrival time difference tau between two transient Rayleigh waves collected by two wave detectors on two adjacent detection points, wherein setting an interval between the two detection points to be arbitrary large on the premise of guaranteeing invariability of foundation soil properties between the two detection points; figuring out phase difference delta phi(f) among different frequency components of the two transient Rayleigh waves of the two adjacent detection points according to the equation that delta phi(f)=delta phi0(f)+2piftau, wherein defining 2piftau as a time difference phase position between two channels; using a phase difference method to figure out corresponding multichannel transient Rayleigh wave phase speed according to the obtained phase difference. The multichannel transient Rayleigh wave detection method gets rid of fetters of a channel interval by introducing the time difference phase position 2piftau into extraction of the Rayleigh wave phase difference among the different frequency components of the two transient Rayleigh waves, uses the two wave detectors to extract the Rayleigh wave phase difference among the different frequency components of the two transient Rayleigh waves, and thereby significantly improves work efficiency, transverse resolution and high frequency resolution of transient Rayleigh wave detection.

Description

technical field [0001] The invention relates to the field of engineering geological survey, in particular to a multi-channel transient Rayleigh wave detection method. Background technique [0002] It is one of the important means of geotechnical engineering and engineering geological survey to understand the properties of rock and soil medium and solve engineering problems by using elastic wave detection method, and it has played an important role in engineering. The physical basis of the elastic wave detection method is the close correlation between the elastic wave propagation velocity of the rock-soil medium and the mechanical properties of the rock-soil mass. By processing the detection record data, the spatial distribution of the elastic wave velocity of the medium in the rock-soil body is extracted, so as to understand the mechanics of the rock-soil mass. Spatial variation of properties and reveal related engineering geological issues. [0003] The arrangement of meas...

AI Technical Summary

Problems solved by technology

Therefore, to complete the detection of the foundation rock and soil mass at a physical point, it is necessary to change the distance between the two geophones several times. However, in the transient method detection, a single excitation will produce fluctuations of various frequency components. For For the measurement of multiple frequency component fluctuations produced by the same excitation, there is no chance to adjust the distance between the two measurement points. Therefore, the existing multi-channel transient Rayleigh wave detection technology meets the requirements of the Rayleigh wave phase difference. On the basis of measuring the track spacing requirements, the measurement method of multi-channel detector arrangement with small track spacing is adopted to form a series of track spacing combinations from small to large. Although this measurement method can simultaneously extract different frequencies generated by the same excitation The phase difference information of the composition, but it needs to be jointly measured by multi-channel geophone arrangement, and the detection efficiency is low; at the same time, this measurement method can only detect the Rayleigh wave phase velocity and different depths of rock and soil within the coverage of the geophone arrangement. An average corresponding relationship of the range is equivalent to a wave velocity test of only one borehole within the range of the geophone array. This test result reflects the average properties of the rock and soil within the range of the geophone array, and cannot reflect the range of the geophone array. Lateral changes in the properties of the inner rock and soil mass, so the lateral resolution is lower

In addition, the highest frequency component that can be measured by this multi-channel combined arrangement measurement method is controlled by the minimum channel spacing of the detector arrangement, so the frequency component that can be measured also has a high-frequency upper limit, that is, the high-frequency resolution of the method force is limited

Images