Abstract
In the current study, the geotechnical properties of the near-surface geological units are collected, tested, correlated, evaluated, and then mapped. In addition, the groundwater level is estimated through comprehensive geotechnical investigations conducted in and around the entire Holy city of Makkah Al-Mukarramah. Based on the measured standard penetration test (SPT), the soil materials vary from soft to very dense materials where SPT ranges from 4 to >50 and increases with depth. On the other hand, the calculated rock quality designation (RQD), the rock quality spans from very poor to good where RQD changes from 0 to 80%. Accordingly, the ground conditions of Makkah can de differentiated into eight subsoil and rock units with various geotechnical properties. Moreover, it is indicated that the physical and chemical nature of these sub-soil and rock units have a considerable effect on the foundations of the constructions that may be risky in the future. The continuous evaluation of the geotechnical and chemical properties for the future projects on these soils and even rock units is highly recommended. These results will greatly support civil engineers and urban designers in the Makkah Al-Mukarramah municipality.