Integrated geoinvestigation for evaluation of an engineering site—a case study from the western Riyadh city, central Saudi Arabia

• Published in: Arabian journal of geosciences Vol. 14; no. 5
• Main Authors: Almadani, Sattam A., Abdelrahman, Kamal, Qaysi, Saleh
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 01.03.2021; Springer Nature B.V
• Subjects: Amplification; Bearing capacity; Cavities; Dimensions; Drilling; Earth and Environmental Science; Earth science; Earth Sciences; Engineering; Karst; Mechanical properties; Modulus of elasticity; Original Paper; P waves; Poisson's ratio; Properties; Refraction; Resonance; Rock properties; S waves; Seismic refraction; Seismic refraction profiles; Seismic velocities; Shear modulus; Shear wave velocities; Soil; Soil dynamics; Soil investigations; Soil properties; Soils; Surface water waves; Surface waves; Two dimensional models; Variable thickness; Velocity; Wave velocity; Saudi Arabia; Riyadh Saudi Arabia; Karst cavities; Saudi Arabia; Dynamic properties; Microtremors; MASW; Riyadh
• ISSN: 1866-7511; 1866-7538
• DOI: 10.1007/s12517-021-06767-3

Microtremors were measured at 18 stations to the west of Riyadh, and the H/V spectral ratio method was used to estimate the resonance frequency and amplification factor. These parameters indicate the presence of foundation bedrocks at various levels with variable thickness of soil where resonance frequency varies from 0.26 to 2.63 Hz, while the amplification factor ranges from 1.1 to 8.9. Moreover, four seismic refraction profiles have been carried out and illustrated two layers: the first of which has a P-wave velocity of 2000 m/s and a thickness of 1.5 m, whereas the second layer is characterized by P-wave velocity from 4010 to 4274 m/s. Besides, four multichannel analyses of surface wave (MASW) profiles have been conducted along the same refraction profiles to estimate the shear wave velocities along these profiles. The constructed 1D and 2D models indicate shear wave velocity ranges from 400 m/s to more than 4000 m/s with horizontal and vertical variation through the investigated area. Furthermore, the dynamic properties of rock and soil materials including Poisson’s ratio, Young’s modulus, shear modulus, material index, concentration index and ultimate bearing capacity have been calculated based on P- and S-wave velocities. These properties reveal less competent to competent material scales. Subsurface karst cavities have been detected in the study area at different depths and various dimensions. It is highly recommended that preventive measures including probing drilling to anticipate karst cavities below the designed foundations must be applied before construction of new engineering facilities in the study area. Otherwise, it will be geotechnical problems in the future.