Geotechnical investigations and shear wave velocity estimation in Makkah Al-Mukarramah metropolitan area, Saudi Arabia

The geotechnical parameters of the near-surface geological units are gathered, tested, correlated, appraised, and then mapped at 199 drill locations. The soil materials vary from soft to very dense based on the measured N-value, which extends from 4 to > 50. The computed rock quality designation (RQD) ranges from very low to good, where RQD values extend from 0 to 80%. The measured N-value has been corrected into N60. Then, the average shear wave velocity (Vs) is computed as a function of energy-corrected SPT blow count (N60). According to NEHRP-IBC standards, the average Vs30 parameter was employed for the site soil zonation map of Makkah. The estimated Vs30 values range from 235 to 1073 m/s. The soils of Makkah’s inhabited wadis fall into the NEHRP-IBC “B,” “C,” and “D” site classes, according to this map. The sites measured in the Al Utaibiyyah District revealed that the district is underlain by thick, weak soil that extends to depths of more than 30 m. Based on the drill profiles, a depth-to-basement map has been created for the city. This map would be quite useful in Makkah’s geotechnical, geological, and hydrological investigations. The Makkah Al-Mukarramah municipality’s civil engineers and urban designers will benefit greatly from these findings. The results of this study are of utmost importance for seismic hazard assessment and risk mitigation of the Makkah area. Moreover, it will improve the Saudi Building Code in terms of shear wave velocity to 30-m depth