Abstract:

The Gediz River Delta soils contain abundant flatty (platy) mica grains. Mica grains can alter static and dynamic engineering characteristics of sandy soils due to their flatty shapes. In this study, influence of mica grains on dynamic shear modulus of sandy soils in Gediz River Delta was investigated. Maximum shear modulus (Gmax), which is a major parameter in dynamic soil response analyses, can be obtained at small deformation amplitudes. Therefore, it is determined through measurement of shear wave velocity. Shear wave velocity provide valuable information about dynamic characteristics of soils. So it is very important to determine the shear wave velocity with high accuracy for dynamic soil response analysis. In this respect, firstly engineering boreholes were drilled and sandy soil samples were recovered along the borehole depth. The mica content of the samples was determined by means of X-RD analysis method. Then test sample contain 1.5%, 10% 20% mica grains were prepared to represent the Gediz River soils. Shear wave velocity of the sand samples were determined with bender element tests under 100 kPa cell pressures in triaxial test device. Followed by the bender element tests maximum shear modules were determined. End of the test program, shear wave velocity of the dense (Dr:55%) samples were determined as 249 m/sn, 214 m/sn and 187 m/sn for 1.5%, 10% and 20% mica content respectively. Mica was reduced the shear wave velocity in considerable percentage about 25% rate. Smiler effect was observed on the maximum shear modules and it is determined as 111.6 MPa, 82.4 MPa, and 62.9 MPa for 1.5%, 10%, 20% mica contents respectively for dense samples (Dr:55%). 20% mica content was reduced the shear wave velocity about 44% rate.

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