APPLICATIONS OF SHALLOW SEISMIC REFRACTION AND SURFACE WAVES (MASW) FOR INFERRINGTHE GEOTECHNICAL CHARACTERISTICS AT CAIRO-BILBEIS AREA, EAST NILE DELTA REGION, EGYPT

Shallow Seismic Refraction Tomography and Multichannel Analysis of Surface Waves (MASW) field
methods were conducted at an area located within Cairo-Bilbeis area, East Nile Delta Region, Egypt. The aim of the
study is the use of these techniques for determining the geotechnical parameters and engineering site characteristics of
the area under investigation. The seismic data were collected along five seismic lines to estimate the compressional (Vp)
wave velocity and shear (Vs) wave velocity for delineating the near-surface ground model beneath the study area.
Sixteen shallow seismic refraction spreads were carried out, each through seven shots located within each spread.
Totally 112 shot records have been acquired through the five lines, the first seismic line consists of four spreads and the
others consist of three spreads. Compressional and shear wave spreads were created, using the seismic refraction
method and data inversion has been made to minimize the error between the observed and calculated travel times and
to improve the velocity models. A number of geotechnical parameters and dynamic characteristics; such as Density,
Poisson's Ratio, Young's Modulus, Rigidity Modulus, Bulk Modulus, Site Class, Material Index, Concentration Index,
Stress Ratio and Ultimate Bearing Capacity (Qult) were calculated to assess the near-surface soil competency from the
seismic velocities (compressional and shear). Soil layers quality is interpreted, using the obtained velocity types. The
soil sections within the study area consist of three layers above the bedrock. The near-surface soil layers evaluatedin
the study area were classified into two site classes, (D and C), according to the Site Classification Scheme of NEHRP
Provisions (2003)