International Journal Of Latest Technology In Engineering & Management (IJLTEM) Volume 9 - Issue 6 {November-December 2024} {Page: 02-12} www.ijltem.com 10.56581/IJLTEM.9.6.02-12 |pAGE| 2 | DETERMINATION OF THE MECHANICAL PROPERTIES OF THE SOIL USING SEISMIC REFRACTION METHOD TECHNIQUE FOR ENGINEERING SITE CHARACTERIZATION IN FUPRE AND ITS ENVIRONS 1 Ighere S.G., 1 Olaseni V.B., 1 Onifade Y.S., 2 Egbai J.C., 3 Utah S. 1 Department of Physics, Federal University of Petroleum Resources Effurun, Nigeria 2 Department of Physics, Delta State University, Abraka, Nigeria 3 Department of Earth Science, Federal University of Petroleum Resources Effurun, Nigeria ABSTRACT: The study was carried out at the Federal University of Petroleum Resources to determine the mechanical properties of the soil to know the subsurface strength. Seismic refraction survey was conducted for data acquisition. Fifteen traverses were used for the data acquisition. The data was acquired using a 24-channel geophone (PASI-GEA 24) and was processed using the GEO-STRU software. A total of three geologic layers were identified along the fifteen traverse each having density of 1800kg/m³, and poisson’s ratio of 0.35 for all the layers. Having a velocity range of approximately 220.5m/s – 371.7m/s for the first layer, the second layer has a velocity range of approximately 381.7m/s – 440.8m/s, and the last layer has a velocity range of approximately 902.1m/s – 1196.2m/s. The shear modulus for layer one and two range from 20mpa - 57mpa and 62mpa - 91mpa, respectively, which indicate that they are composed of silty sand. Layer three's shear modulus indicates that it is formed of dense sand with a shear modulus range of 338mpa – 594.38mpa. The first layer young's modulus ranges from around 54.53mpa – 154.98mpa for all the traverses which suggests loose sand, the second layer young's modulus also range from163.40mpa – 246.56mpa suggest sandy clay as the main material, and the third layer young's modulus ranges from about 912mpa – 1604.81mpa suggests dense sand. INTRODUCTION Due to the failure to conduct the required investigations before the construction of structures, developing countries have endured repeated collapse of engineering structures throughout the years. Recently, the statistics of building and engineering structure failures in these countries have risen exponentially (Alabi, 2020). The number of structural breakdowns in Nigeria in recent years is horrifying (Akintorinwa and Adeusi 2009). The geotechnical design necessary for projects requiring deep and shallow foundations, basements, slopes, tunnels, highways, embankments, mining tailings, seismic hazard assessments, site cleanup, and ground improvement must include site characterization as a crucial component (Lehane et al., 2018). It is crucial to assess the subsurface integrity before construction because when an engineering structure's foundation is built on a less capable earth layer, it poses a major threat to the structure and may even cause it to collapse (Ayodele et al, 2019). Geophysical methods are often used in site investigation to determine the overburden thickness and to map subsurface conditions prior to excavation and construction. Geophysical data is an important parameter in contributing to the design and construction of Civil Engineering structures such as buildings, roads and dams. Electrical resistivity and seismic refraction methods are the most common geophysical techniques used for this purpose (Kurtenacker, 1934; Drake, 1962; Burton, 1976; Nunn, 1979; Keary and Brooks, 1984). However, in resistivity method, the depth of investigation and subsurface sections captured is limited to the array techniques employed during data acquisition that is resistivity sounding or resistivity imaging. Seismic method is the geophysical method that gives the most detailed picture of subsurface geology because it gives us the opportunity to view the subsurface layers in two-dimensions (2D) or three-dimensions (3D) and to greater depths than that captured in resistivity method. Therefore, geologic sections computed from seismic method is a more reliable model of the subsurface since the earth is heterogeneous and 3D in geometry. That is why seismic method is often used to determine the characteristics of subsurface soils and rocks, (Ayolabi 2004) and structural setting of an area. The technique (seismic refraction) finds application in the determination of rock competence for engineering application, depth to bedrock, groundwater exploration, crustal structure and tectonics. To fully understand a region's near-surface geology, it is important to examine the soil (Adewoyin et al., 2021). The most common methods for characterizing soil are drilling, excavation, and geophysical studies. However, it may be difficult to extrapolate the same result in the expansion of a much wider space of the region studied because the results from these methods are site-specific and are only applicable to the tested spot, in