FIELD CHARACTERIZATION OF WEATHERED ANKARA ANDESITES

This paper presents held and some index properties of weathered Ankara andesites, carried out over a period of 4 years. Ankara andesites are distributed widely around the city of Ankara, on which numerous impor tant structures have been founded. Thus, the weathering characteristic s of Ankara andesites, both from the engineering geological and the ro ck mechanics points of view are important. The held work involved asse ssment of the rock mass weathering grades, conduction of simple field tests, Schmidt hammer and point load tests on the rock materials, char acterisation of discontinuities, and collection of representative samp les from each weathering grade for laboratory testing. The relationshi p between the experimentally determined parameters and quantitative en gineering geological descriptions provided a simple geological method for the assessment of the design parameters and mapping the distributi on of mass weathering grades. As a result of the evaluation, an ideali zed weathering profile and the scale of rock mass weathering grades to gether with their range of thicknesses were proposed. Some index tests , such as effective porosity, Schmidt hammer value (SHV), point load s trength and seismic velocity, provided good relations with the degree of weathering.