Geotechnical Engineering Evaluation of Superficial Deposits Utilizing Seismic Methods at Al al-Bayt University, Jordan

Fatima Ghanem

doi:10.46717/igj.54.1d.2ms-2021-04-22

Abstract

Integration of seismic refraction tomography and multi-channel analyses shear wave methods were used at Al al-Bayt university campus in Mafraq, NE Jordan to delineate the shallow subsurface layering and determine their geotechnical properties, in addition, to estimate the geotechnical engineering parameters of the superficial deposits for detailed purposes. The P-wave refraction velocities were found to range from 180 to 2300 m/s for the three identified layers which indicating superficial soil deposits with an increasing degree of compaction with depth. The S-wave velocities were found to lie in a narrow velocity range (250 to 600 m/s), which badly resolved the subsurface layering. Moreover, four soil samples were taken from the sites of seismic survey points for density calculations. The average calculated density was found to be 1.85 g/cm3. Two soil samples from nearby seismic profile-1 and seismic profile-4 were tested for geotechnical properties. The results showed that the seismic method is an effective tool to estimate the different elastic moduli; Poisson's ratio, Young's modulus, Bulk modulus, Shear modulus, Lame's constants, and geotechnical engineering parameters; N-value, bearing capacity, material index, concentration index, and stress ratio of the superficial soil deposits. The study recommends conducting a detailed geophysical study before starting any type of geoengineering construction in the area.

Highlights

Several geophysical methods have been suggested for engineering site studies, it was considered as progressively acceptable tools to give more information about the subsurface structures and lithology for seismologists and civil engineers (Benson and Yuhr, 2002; Goldstein, 1994; Benson et al 1983; Al-Kubaisi and Shakir, 2018; Alsamarraie, 2020)
It was found that the topsoil can be described as clayey silty sand at 2 m depth, the soil mixed with gravel of limestone and chert and at the 5 m below surface the soil mixed with chalky marl and gravel of chert and limestone (AABU, 2018)
The shear modulus (μ), Bulk modulus (K) and Lame’s Constant (λ) calculated from seismic velocities Multichannel-AnalysesDOI: 10.46717/igj.54.1D.2Ms-2021-04-22Shear Wave (MASW) measurements were found to be higher than those measured in Royal Scientific Society (RSS) laboratories shown as Figs.11b, 11d and 11e respectively

Summary

Introduction

Several geophysical methods have been suggested for engineering site studies, it was considered as progressively acceptable tools to give more information about the subsurface structures and lithology for seismologists and civil engineers (Benson and Yuhr, 2002; Goldstein, 1994; Benson et al 1983; Al-Kubaisi and Shakir, 2018; Alsamarraie, 2020). The seismic refraction tomography (SRT) method is commonly used to detect the physical properties of the subsurface in order to mapping the horizontal and vertical variations of subsurface geological features and soil characterization in the site investigations (Al-Heety and Shanshal, 2016). Shear Wave (MASW) method is used in geotechnical studies to estimate shear velocity (Vs) of subsurface materials, the relation between (Vs) and depth, and other geotechnical parameters of soil. It is used commonly for shallow depths (Priya and Dodagoudar, 2017; Park, 2013). Several geophysical studies have been carried out to determine the layers of various seismic velocities and estimate engineering parameters in different parts of the world by seismic methods ( Abudeif et al 2019; Srinivas et al 2018; Al-Heety and Shanshal, 2016; Pegah and Liu, 2016; Al-Saigh and Al-Heety, 2013)

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Conclusion