Determination of soil features by geological and geophysical methods in Sakarya province sapanca district mahmudi̇ye village

Keywords: sakarya, sapanca, development plan, geology, geophysics, geotechnics Geological and geophysical investigations have been carried out in Sakarya province, Sapanca Mahmudiye District, to revaluate the suitability for settlement of 17631 m2 old settlement area. In the study area, seven mechanical foundation drilling with a total depth of 65 m and 8 research research pits were used for the study. A Standard Penetration Test (SPT) was carried out at each 1,5 m inside the boreholes. In order to determine dynamical parameters from geophysical methods 6 seismic refractions with a laying length of 24 m, 8 Schlumberger electrode array Vertical Electrical Soundings (VES) and 3 microtremors were investigated. As a result, a decomposed schist units of 0.30-6.00 m thicness which is the residual zone product of the Permo-Triassic Sultaniye Metamorphites and fractured schist units belonging to the Sultaniye metamorphites are observed below these units. These schists were observed to be brown-gray, yellowish gray, greenish gray and dark gray. As a result of seismic refraction studies, two underground layers are determined with VP-VS velocities as Vp1=451-746m/s, Vs1=181-451m/s, Vp2=1231-1707m/s, Vs2=523-785m/s With these values the soil groups are calculated as the 1st layer types are Z3-C and the 2nd layer is Z2-B. The spectral magnification (ground amplification) in the dominant period interval calculated in the microtremors taken are lowest 1.80 and the highest 1.86. According to these results the hazard level of the area with respect to spectral amplification is classified as A (Low). The Schlumberger electrode array Vertical Electrical Sounding (VES) values were found to be between 114-913 ohm.m. Geological features such as fractures / faults were not observed in the study area.