K. Zorlu

A fuzzy model to predict the uniaxial compressive strength and the modulus of elasticity of a problematic rock

Abstract Although the uniaxial compressive strength and modulus of elasticity of intact rocks are highly important parameters for rock engineering and engineering geology projects, the necessary core samples cannot always be obtained from weak, highly fractured, thinly bedded, or block-in-matrix rocks. For this reason, the predictive models are often employed for the indirect estimation of mechanical parameters. However, to obtain the realistic values is very important for a predictive model. In this study, some predictive models using regression analysis and fuzzy inference system have been developed for the greywackes cropping out in the city of Ankara and its close vicinity. For this purpose, a series of rock mechanics tests were applied and the relevant intact rock parameters were obtained. Following the tests, descriptive statistical studies on the parameters, regression analyses and construction of fuzzy inference system studies were carried out. While meaningful relationships were not obtained from the simple regression analyses, both multiple regression analyses and the fuzzy inference system exhibited good predictive performance. In addition to the coefficient of correlation, the values account for (VAF) and the root mean square error indices were also calculated to check the prediction performance of the obtained models. The VAF and root mean square error indices were calculated as 41.49% and 15.62 for the uniaxial compressive strengths obtained from the multiple regression model; 64.02% and 8.85 for the modulus of elasticity values obtained from the multiple regression model; 81.24% and 13.06 for uniaxial compressive strengths obtained from the fuzzy inference system; and 78.64% and 6.87 for the modulus of elasticity values obtained from the fuzzy inference system. As a result, these indices revealed that the prediction performances of the fuzzy model are higher than those of multiple regression equations.

Estimating the uniaxial compressive strength of some clay-bearing rocks selected from Turkey by nonlinear multivariable regression and rule-based fuzzy models

: Although the use of predictive models in rock engineering and engineering geology is an important issue, some simple and multivariate regression techniques traditionally employed in these areas have recently been challenged by the use of fuzzy inference systems and artificial neural networks. The purpose of this study was to construct some predictive models to estimate the uniaxial compressive strength of some clay-bearing rocks, depending on examination of their slake durability indices and clay contents. For this purpose, the simple and nonlinear multivariable regression techniques and the Mamdani fuzzy algorithm are compared in terms of their accuracy. To increase the accuracy of the Mamdani fuzzy inference system, the weighted if–then rules are extracted. To compare the predictive performances of the models, the statistical performance indices (root mean square error and variance account for) are calculated and the results are discussed. The indices reveal that the fuzzy inference system has a slightly higher prediction capacity than the regression models. The basic reason for the higher performance of the fuzzy inference system is the flexibility of the fuzzy approach.

DETERMINATION OF PREDOMINANT SITE PERIOD OF LOOSE TERRESTRIAL UNITS (CALICHE) WITH MICROTREMOR MEASUREMENTS

Kurak-Yari kurak iklim bolgelerinde gozlenen kalis turu birimler; dusey yonde zonlanma gosteren, karasal kalsiyum karbonat birimler olarak bilinmektedir. Kalis profi linin en ustunde zayif kaya niteligindeki sert kalis, onun altinda ise gevsek zemin karakterindeki yumusak kalis profi li yer almaktadir. Kalisler, cogunlukla doygun olmayan zonlarda, toprak, kaya ve bozunmus malzemenin yer degistirme ve/veya cimentolanmasina isaret ederler. Calisma alani Adana ilinin dogusunda yer alan kalis birimlerini kapsamaktadir. Bolgede oldukca genis bir yayilim gosteren Kuvaterner yasli kalis, ozellikle egimin dusuk oldugu, bolgelerde bulunmaktadir. Adana Havzasindaki paleosolik kalisler, karbonatca zengin yuzey sulariyla birlikte, suzulme, kapilarite ve ayrisma olaylarini takiben, once sedimantolojik daha sonra da pedolojik bir mekanizma sonucu olusmuslardir. Adana ili I. ve II. derece deprem bolgesinde yer almakta olup, tarihsel ve aletsel donemlerde pek cok depreme sahne olmustur. Ozellikle 1998 Adana depremi sirasinda en buyuk yapisal hasarin kalis profi li uzerinde yer alan binalarda meydana geldigi gozlenmis olup, buna kalis profi linin dusey yonde sergiledigi litolojik degisimin neden oldugu dusunulmektedir. Bu calisma ile sert kalis ve yumusak kalis sinirindaki ve litolojik degisikliklerin oldugu sinirlardaki goreceli zemin buyutmesi ve yatay-dusey spektral orani (H/V) incelenistir. Bu amacla, sert kalis ve yumusak kalis arasindaki H/V farkinin ortaya konabilmesi icin, sert kalis uzerinde ve sert kalisin olmadigi, profi lin dogrudan yumusak kalis ile basladigi lokasyonlarda 24 adet mikrotremor olcumu yurutulmus ve H/V farki ortaya konmustur.

Prediction of the Collapse Index by a Mamdani Fuzzy Inference System

Determination of collapse potential of collapsible grounds is an important problem for civil engineers. However, this requires extensive field and laboratory works. For this reason, prediction tools for this purpose are highly attractive for engineers. Considering this difficulty, development of a Mamdani fuzzy inference system for prediction of collapse index is the main purpose of the study. The fuzzy inference system developed in the study includes two inputs, one output and 25 lingusitic if-then rules. The performace of the fuzzy inference system is checked by various indices and these indices reveal that the fuzzy inference system has a significant prediction performance.