Description of the weathering states of building stones by fractal geometry and fuzzy inference system in the Olba ancient city (Southern Turkey)

Applying an engineering geology research to historical places under conservation is very difficult because of sampling restrictions. In order to overcome this difficulty, some non-destructive methods have been used to assess the weathering degrees of the building stones. For this purpose, intensive field studies including the Schmidt hammer test, development and application of a simple visual classification and photograph shootings for fractal geometry have been carried out. A total of 114 blocks were employed during the field studies. With increasing the weathering, the Schmidt hammer values and the fractal dimensions of the blocks systematically decrease. In the final stage of the study, a fuzzy inference system to quantify the weathering degree of the building stones have been constructed. The performance of the inference system is assessed by various methods and the results show that this fuzzy inference system produces plausible results and has a higher prediction capacity. Combination of the various employed methods provides a non-destructive and a simple methodology for the description of the weathering states of the building stones. In this study, the advantages of fractal geometry are considered because its main advantage is to analyze the scale invariance. However, to provide a second check on the weathering descriptions of the blocks, the Schmidt harness is utilized. The approach can be applied on the determination of weathering states of building stones and blocky rock masses.