Multichannel Analysis of Surface Waves (MASW) to Estimate the Shear Wave Velocity for Engineering Characterization of Soils at Hawassa Town, Southern Ethiopia

Abstract

Site characterization is a prerequisite for the successful and economic design of engineering structures and earthworks by providing geological information for any proposed project. Until now, no detail study has been carried out on the site characterization and classification using shear wave velocity (Vs) up to the top 30 m depth in Hawassa town. For this study, multichannel analysis of surface waves (MASW) was used to determine the variation of Vs for a proper civil engineering design in the town. In addition, vertical electrical sounding (VES) and standard penetration test (SPT) were employed to characterize the near-surface materials. The Vs30 map was prepared for Hawassa town using the estimated Vs30 values which ranges from 248.9 m/s to 371.3 m/s while the SPT-N values were ranges from 5bpf to 50bpf. The correlation of Vs and SPT-N values has been done by considering both corrected and uncorrected SPT-N values. The VES result showed that groundwater is found at a shallow depth. The correlation of Vs and SPT-N value was validated using regression model. The 1D Vs profile and 2D cross-section showed low Vs at a shallow depth. The near-surface soils of the town are classified based on the Vs30 as site class C (stiff soil and soft rock) and D class (stiff soils) according to the NEHRP (Natural Earthquake hazards Reduction Program) and as subsoil classes B and C according to the Eurocode 8. The geotechnical tests also showed that the soils in the study area are silty sand, sand and silty sand with some gravel. The low Vs values observed at a shallow depth should be given much attention during foundation design for the stability of civil engineering structures.

Estimating shear wave velocity and site characterization of western Riyadh City, Saudi Arabia based on multichannel analysis of surface waves

“…There are several geophysical approaches for the evaluation of in-situ Vp and/or Vs and obtaining a 1D Vs profile or 2D Vs cross-sections versus depth (e.g., Al-Saigh and Al-Heety, 2013;AL-Saigh & AL-Heety, 2018;Abdelrahman et al, 2021a;2021b). This important parameter can be precisely obtained using surface geophysical methods to evaluate the appropriateness of surface materials for roads, building constructions, and foundations like MASW methods (Socco and Strobbia, 2004;Fnais et al, 2015;Abd El-Aal et al, 2016;Al-Amri et al, 2016;Rehman et al, 2016;Aldahri et al, 2017;Alamri et al, 2020;Igwe and Umbugadu, 2020;Mogren et al, 2020;Naji et al, 2020;Al-Heety et al, 2021;Almadani et al, 2021;Alzahrani et al, 2021;Abdelrahman et al, 2021c;El-Raouf et al, 2021;Abdallatif et al, 2022;Al-Heety et al, 2022;Ayele et al, 2022;Ferguson and Gautreau, 2022;Jusoh et al, 2022). This method is dependable, non-invasive, and cost-effective in engineering practices.…”