Surface Wave Dispersion Characteristics And Exploration Applications Of Karst Strata

Surface wave exploration technique is a very mature shallow seismic exploration method, with good results in the engineering investigation resolution and detection accuracy. Conventional surface wave exploration method once can only collected a point of information, However, multi-channel transient surface wave by rolling collected, gathering more seismic surface wave data and information, The final result is a disposition of the geological section, can better reflect the real geological formations under the circumstances. By using multi-channel transient surface wave technology, can improve the resolution and detection precision engineering probe to some extent. Paper based on multi-channel transient surface wave method of technical means, Using several typical geological structure model staggered finite difference forward modeling, at different stratigraphic structures dispersion curves exhibited a different morphology.Paper in half the space consisting of different media (two solid media and multi-media) dispersion curves calculated theoretically, and dispersion curve extraction methods (τ—p transform algorithm, f—k transform algorithm and phase shift approach) were studied. By build several typical stratum structure model, Use of staggered grid2order time difference approximation, staggered grid12order spatial difference approximation, Carried forward modeling of surface waves, Studied the surface wave propagation characteristics in these different structures in the stratum(half-space homogeneous medium model with cave, Horizontal surface with cave and an inclined surface with cave model, Soft seams model, fault model, empty-hole model of limestone strata), Also gained snapshots of wave and dispersion of information in these ground structure, Comparative analysis of its wave dispersion curves and snapshots, got conclusions that scattered in different formations curves exhibit different morphological characteristics, Provide scientific guidance for multi-channel transient surface wave technology apply in engineering geological exploration. Through two field tests to detect karsts formations, Comparison found, Rayleigh wave method for shallow geological anomaly has a higher resolution, with higher accuracy compared with other methods, Thus, Multi-channel transient Rayleigh wave can be determined as an effective methods in karsts formations exploration. Paper also pointed out the shortcomings of Multi-channel transient Rayleigh technology applications and future research directions, In particular surface wave propagation and dispersion characteristic studies in a number of complex geological characteristics of the structure(Such as:mined-out area, fissures cracks, other high-speed hard mezzanine etc.) in the forward modeling, Often detect accuracy is not high in these complex geological structures, Led to the erroneous interpretation of geological anomalies. Should study focus on strengthening the scattering characteristics, attenuation characteristics and elliptical polarization characteristics to improve full use of Rayleigh multi-attribute information, Thereby enhancing the ability of Rayleigh wave to exploration of complex geological structures.