Geotechnical comparison of weathering degree and shear wave velocity in the decomposed granite layer in Hongseong, South Korea

Abstract

As part of a fundamental characterization of a subsurface layer in South Korea, the weathering degree and shear wave velocity (V S ) were evaluated in a decomposed granite in Hongseong, using X-ray fluorescence analyses and site investigations, including borehole drilling with standard penetration test (SPT) and in situ seismic tests. The subsurface layer was composed of a weathered layer 10-40 m thick at most sites. Weathering degree analyses indicated that three chemical weathering indices, the modified weathering potential index (MWPI), Vogt ratio (VR), and weathering index of Parker (WIP), generally increased with decreasing depth. In situ seismic tests revealed that V S ranged between 200 and 500 m/s in the weathered layer. Using the V S and N values from the SPT at borehole seismic testing sites, correlations between V S and N values were established for the weathered layer. Furthermore, examination of the relationships of the V S and N values with the MWPI, WIP, and 100/VR indices showed that the index values increased linearly with increasing V S and exponentially with increasing N values.

Characterization of the shallow subsurface structure across the Carrascoy Fault System (SE Iberian Peninsula) using P-wave tomography and Multichannel Analysis of Surface Waves

“…Therefore, the velocity and dispersion characteristics of surface waves (MASW method) are used to determine the variation of shear wave velocities with depth (Foti et al, 2018;Park et al, 1999). The MASW technique assumes that the subsurface is a laterally homogeneous layered earth media, in which the average Odum, et al, 2007;Sun et al, 2015]). The latter is included in the last two columns.…”

“…The latter is included in the last two columns. (Odum et al, 2007;Sun et al, 2015)). The latter is included in the last two columns velocity can be assigned to the middle of the receiver spread (Foti et al, 2018;Socco et al, 2010).…”

A National VS30 Model for South Korea to Combine Nationwide Dense Borehole Measurements With Ambient Seismic Noise Analysis

“…We examine the validity of the V S 30 model from comparison with in‐situ field measurements in local regions. We collect in‐situ measurements at 28 sites in Gyeongju and 16 sites in Hongseong (Kim et al., 2002; Sun et al., 2006, 2007, 2013) (Figures 20a and 20b). The in‐situ measurement sites are located in small regions (Figures 20c and 20d).…”

Estimation of Pressuremeter Modulus and Limit Pressure in Weathered Granite Based on the SPT-N Value and Chemical Weathering Index: A Case Study in South Korea

“…Despite this limitation, the geotechnical properties of weathered granite (especially highly and completely weathered granite rock) are generally evaluated by SPT in practice field. Thus, many studies have used the converted SPT-N values linear extrapolated to the N value representing the number of blows required to penetrate 30 cm [16][17][18]. In the estimation of the geotechnical properties using the N value, an energy correction is necessary in order to obtain reliable results.…”