Geotechnical Evaluation of Soil for Foundation Purposes Using MASW in Al-Najaf Al-Ashraf City, Iraq

Multichannel Analysis of Surface Waves offers a suitable method for evaluating sites and conducting geotechnical investigations of subsurface rocks and soils. This study aims to assess the geotechnical properties of subsurface soils and identify areas with cavities in the Al-Kadiar Village area. The shear wave velocity (Vs) was calculated using the Multichannel Analysis of Surface Waves approach. A 72-meter Multichannel Analysis of Surface Waves profile was conducted to measure Vs, with shear waves generated using a 10 kg hammer and an ABEM Terraloc Pro seismograph, with an offset distance of 3 m and multiple strikes. Fieldwork was carried out using 24 geophones of 4.5 Hz frequency, and seismic data were processed using SeisImager Software. Five layers were found in the research area after processing the data and extracting the one-dimensional velocity model. The silty sand in the first layer is somewhat saturated, followed by clayey silty sand in the second layer, an interlayer of clayey silty sand and silty sand in the third layer, and silty sand with dried gypsum-rich deposits in the fourth layer. The final layer is sandy silty clay, partially saturated or with high clay content. the majority of foundation sites contain type D2 soil, which translates to medium cohesive layers, according to the average shear wave velocity (Vs30) values for the five layers down to a depth of 30 m. Along with other geotechnical features and qualities taken from the Multichannel Analysis of Surface Waves study, a geotechnical evaluation was also conducted utilising shear wave velocity (Vs) profiles. These parameters were used to estimate significant soil properties, providing insight into subsurface conditions. This kind of information plays an important role when it comes to checking how stable the soil is and spotting any possible geotechnical issues that might come up. The results provide a clearer and more accurate picture of what’s going on below the surface in the study area, which is crucial for planning infrastructure and avoiding future geotechnical problems.