Geological-geotechnical investigations of the historical Diriyah urban zone in Riyadh, Saudi Arabia: an integrated approach

One hundred seventy geotechnical boreholes, two geo-seismic profiles of multichannel analyses surface waves (MASW), and geoelectrical cross-sections electrical resistivity tomography (ERT) were carried out in the historical Diriyah urban zone. The borehole samples analyzed for parameters standard penetration test (SPT N-value), rock quality designation (RQD), compressive strength (CS). Moreover, P- S-wave velocities have been calculated. measured SPT N-value has corrected to amend N 60 parameter. According , type, lithological, soil divided into five distinct subsurface layers. It is indicated, all recorded depths, these sediments become denser with depth where values increase from 5 88 downward. grain size distribution, major part sites composed sand varies low medium compressibility. estimated RQD range 100 indicating rocks significant variations their physio-chemical characteristics. Furthermore, widely between 152.3 1,104.2 kg/cm 2 which represents diverse geodynamic behavior under civil engineering constructions. Besides, stiffness indicated by Shear-wave velocity (Vs) layers, 171.3 456.2 m/s. findings MASW profiles, shear wave shown be decreasing profile 1 depths 8 14 m, 1,000 1,500 m/s, a weak zone filled secondary materials. But line shows how decreased m–11 ranged thus zones ERT cross-sections, are found at same well associated findings. can concluded that there number varying shapes, dimensions zone’s near-surface deposits engineers, planners, developers should consider before undertaking any construction or developmental work involving engineering.