Analysis on shear wave velocity structure of a gravel landslide based on dual-source surface wave method

Abstract

The depth and geometry of the potential sliding surface is the fundamental basis for evaluating the mechanism and performing mitigation measures of a landslide. The variation of shear wave velocity can directly reflect the characteristics of the strata structure in a landslide. For traditional methods (PS logging, surface exploration, H/V spectral ration and microtremor survey etc.), it is difficult to assure a large probing depth and high resolution at the same time. Joint observations were conducted using initiative-source multichannel analysis of surface wave (MASW) method and passive-source microtremor survey method (MSM) on the Xishan Village landslide located in Li County, Sichuan Province, China. Both frequency wave number method (F-K) and spatial auto correlation method (SPAC) were conducted to process the digital signal to analyze the shear wave velocity in the landslide, respectively. The Dual-source Surface Wave (DSSW) method was combined with MASW and MSM. The detected 2D profiles from the DSSW method showed that the landslide strata information was consistent with the borehole data. The results suggested that average depth of the potential sliding surface was about 50 m, of which the undulating shape was also clear. The boundary of the potential sliding surface was formed by weathered phyllite. It indicated that the DSSW method could assure both the exploration depth and enabling good resolution at the same time, which was an effective method to detect landslide structure and expected to be applied in survey of other geological hazards.