Hanifi Canakci

Prediction of compressive and tensile strength of limestone via genetic programming

Accurate determination of compressive and tensile strength of limestone is an important subject for the design of geotechnical structures. Although there are several classical approaches in the literature for strength prediction their predictive accuracy is generally not satisfactory. The trend in the literature is to apply artificial intelligence based soft computing techniques for complex prediction problems. Artificial neural networks which are a member of soft computing techniques were applied to strength prediction of several types of rocks in the literature with considerable success. Although artificial neural networks are successful in prediction, their inability to explicitly produce prediction equations can create difficulty in practical circumstances. Another member of soft computing family which is known as genetic programming can be a very useful candidate to overcome this problem. Genetic programming based approaches are not yet applied to the strength prediction of limestone. This paper makes an attempt to apply a promising set of genetic programming techniques which are known as multi expression programming (MEP), gene expression programming (GEP) and linear genetic programming (LGP) to the uniaxial compressive strength (UCS) and tensile strength prediction of chalky and clayey soft limestone. The data for strength prediction were generated experimentally in the University of Gaziantep civil engineering laboratories by using limestone samples collected from Gaziantep region of Turkey.

Prediction of compressive and tensile strength of Gaziantep basalts via neural networks and gene expression programming

In this paper, two soft computing approaches, which are known as artificial neural networks and Gene Expression Programming (GEP) are used in strength prediction of basalts which are collected from Gaziantep region in Turkey. The collected basalts samples are tested in the geotechnical engineering laboratory of the University of Gaziantep. The parameters, “ultrasound pulse velocity”, “water absorption”, “dry density”, “saturated density”, and “bulk density” which are experimentally determined based on the procedures given in ISRM (Rock characterisation testing and monitoring. Pergamon Press, Oxford, 1981) are used to predict “uniaxial compressive strength” and “tensile strength” of Gaziantep basalts. It is found out that neural networks are quite effective in comparison to GEP and classical regression analyses in predicting the strength of the basalts. The results obtained are also useful in characterizing the Gaziantep basalts for practical applications.

Pile foundation design using Microsoft Excel

This article presents a program called Pile‐D developed for the teaching of pile foundation design to undergraduate level geotechnical engineering students. The program performs drained and undrained analysis for frictional resistance of the pile in clay, and uses critical depth approach for the analysis of the pile in sand.

Use of ranking measure for performance assessment of correlations for the compression index

In order to provide a fast and cost-effective solution, particularly for preliminary evaluations in many design situations of constructions, a number of numerous empirical equations for estimation of compression index simply established with soil index properties are intensively used for consolidation settlement. However, they may not be appropriate when considered for different regions dependent upon local site conditions. Thus, it is important to know the performances of the empirical equations with local data. This paper investigates the performances of some of the empirical equations for estimation of compression index for fine-grained soils of Baghdad City along the Tigris River. Four criteria including error and ranking measurement were employed as bases of evaluation: root mean square error, the ratio of estimated to measured (laboratory) compression index, ranking index and ranking distance (RD). The last two (ranking index and RD), a relatively new approach of ranking measurement, involve with the accuracy and precision of estimated result with actual data. The assessment ultimately has been done regarding the RD, since it is a comprehensive statistical parameter that gives equal weight to the accuracy (mean) and precise (standard deviation) of estimation, as compared with others. It is found from the analysis results that the overall best estimation of compression index for the data of Baghdad was obtained by the empirical equations established with liquid limit proposed by Cozzolino and Azzouz, Krizek, and Corotis. The results indicate that the most reliable equation correlates compression index with liquid limit.

Examination of the mechanical properties and failure pattern of soilcrete mixtures modified with rice husk ash

Abstract This paper evaluates the unconfined compressive strength (UCS), stability (bleeding), modulus of elasticity and failure patterns of cement-based grout mixtures that were prepared by placing of rice husk ash (RHA) with cement at various water to binder (w/b) ratios. In order to investigate these parameters, UCS and bleeding tests were conducted on the soilcrete samples that prepared at 5, 10, 20 and 30% replacement level of RHA with cement for .75, 1.00 and 1.25 w/b ratios. Test results showed that the UCS values of the samples for 28 day curing are higher than 1 MPa and E/q u ratios obtained from soilcrete mixtures were less than the corresponding value from slurry clay–cement mixes given in the literature. In addition, all bleeding test results are lower than the level of .5%. Finally, most of the mixtures prepared for this study failed along foliations.

Effect of sand column on compressibility and shear strength properties of peat

Abstract Peat is found in many countries throughout the world where it can be generally seen in thick layers in limited areas. Peat is an extreme form of soft soil and is considered problematic due to the low shear strength and large compressibility. This project presents laboratory finding on the compressibility and shear strength characteristics of fibrous peat with sand column. The peat used in the study is classified as fibrous peat and H1–H4 in Von Post scale. Its liquid limit is 119%. In all tests, the peat used for the tests passing 2 mm and remain on .15 mm. The rounded sand used for making sand column is poorly graded passing from 2 mm sieve size and retaining on 1 mm sieve size. The tests conducted to investigate effect of area ratio of sand column on shear strength and compressibility of the peat. Three different area ratios were used for both compressibility and shear strength tests. Consolidation test results showed that when the area ratio increases compressibility characteristic of the peat improved. Shear strength of the organic soil was also affected from the sand column.

Development of Correlations for Compression Index

Compression index is one of the most important properties of soils widely used for estimation of settlement during design of foundations. In particular, for routine test requirements, limited laboratory facilities and preliminary evaluations, various equations are available in the literature to simply estimate the compression index using some soil index properties. However, applicability of these equations is often limited for the interested site due to their establishment from different databases. Thus, it is more realistic way to employ the correlations developed using local data of region, provided that data is available. In this viewpoint, this paper aims to develop correlations for the compression index dependent upon the soil index parameters of natural moisture content, liquid limit and initial void ratio for fine‐grained soil of Baghdad city. From the developed correlations, it is obtained that the best estimations of compression index is correlated by liquid limit as single variable, and by liquid limit and initial void ratio as double variable. It is clear that use of the developed correlations is more suitable specifically for Baghdad region for preliminary evaluations of foundation settlement