Hakan Ersoy

Spatial and multi-criteria decision analysis-based methodology for landfill site selection in growing urban regions

The construction of landfills is not an alternative option, since a landfill is always a necessary component of the specific waste management system that will be developed. One of the serious and growing potential problems in large urban areas is the shortage of land for waste disposal. In solid waste management programmes, use of geographic information systems (GIS) is a very significant tool because the selection of a suitable site is a very time-consuming process. The analytic hierarchy process in GIS provides objective mathematics to process the subjective preferences of individuals or groups and arrive at a decision. The present paper describes a spatial methodology which comprised several methods, such as multi-criteria analysis, that originate in different scientific fields. The final goal of the methodology was to evaluate the suitability of the studied area (Trabzon, NE Turkey) in order to optimally select a landfill site. Different constraint maps were overlaid with spatial analysis modules to obtain a final suitability map for Trabzon City and five suitable areas were identified. An analytic hierarchy process was applied to select the most suitable solid waste disposal site for municipal waste in the city among these alternative candidate sites. The Düzyurt area was found to be the most suitable solid waste disposal site. However, geotechnical investigations indicated that some remedial measures would be needed before this landfill site could be used.

A comparative assessment of indirect methods for estimating the uniaxial compressive and tensile strength of rocks

The uniaxial compressive and tensile strength of rocks are crucial parameters in the design stage of geotechnical structures. However, direct determination of these parameters is expensive, troublesome, time consuming, and sometimes requires high-quality core samples for tests. Therefore, this study aimed to determine the applicability of the point load strength index and Schmidt hammer hardness values to estimate the uniaxial compressive strength and tensile strength of rocks based on the regression analyses. Further, multiple regression analysis was used on datasets obtained from tested rocks. For these purposes, representative samples of volcanic, sedimentary, and metamorphic rocks were collected from 37 different points along a tunnel alignment in Northeast Turkey where hundreds of underground projects are being constructed. Results from the regression analyses showed the existence of satisfactory correlations. The results were also compared and discussed with the results obtained by other researchers conducted on different types of rocks.

Seismic tomography and surface wave analysis based methodologies on evaluation of geotechnical properties of volcanic rocks: A case study

Economic development, industrialization and dense population in Trabzon City have caused residential construction to increase by 300% in the last decade. The settlement area is mountainous and covered with heavy vegetation. Thus, the steep-sided topography and heavy precipitation means floods and landslides are common and in areas with little flat land. Since the mass movements in some parts of city create an enormous danger for buildings, site selection for residential areas becomes increasingly important. This paper describes geotechnical and seismic properties of Tertiary volcanic rock and establishes the link between these units and construction. In this study, refraction tomography and multichannel analysis surface wave methods were applied in order to seek the best construction site in the residential area. The results of the geophysical study were compared with the borehole applications. A series of geomechnical tests were carried out on the core samples. Following that, statistical correlations were conducted by regression analysis to evaluate relationships between measured parameters. Rock Quality Designation and weathering degree were also determined. The methodology defined in this investigation proves to be an appropriate approach to determine geotechnical properties of the foundation rocks and soils and a proper guide on future geotechnical studies for other cities.

Radioactivity measurements and risk assessments of spa waters in some areas in Turkey

ABSTRACT The current study presents the results of the activity of radionuclides in spa waters, and evaluates their radiological influences on the population consuming these waters in the Central and Eastern Black Sea regions of Turkey. Since these waters are used for therapy and consumption purposes unconsciously, their radiological impact on the people was computed by taking into consideration the annual intake through ingestion of 226Ra, 232Th, 40K, 137Cs and 222Rn. The mean activities were estimated to be 11.35 for gross alpha, 6.23 for gross beta, 2.96 for 226Ra, 0.42 for 232Th, 0.069 for 137Cs, 0.19 for 40K, and 267 Bq L–1 for 222Rn, respectively. The estimated effective doses from spa water were found to be 49.77 µSv a–1 (226Ra), 5.95 µSv a–1 (232Th), 0.07 µSv a–1 (137Cs), 0.83 µSv a–1 (40K) and 56.03 µSv a–1 (222Rn). These values were evaluated and compared with related verified values from literature. Also, physico-chemical characterizations of spa water samples considered in the current study were investigated. This study would be useful for consumers and official authorities for the assessment of radiation exposure risk due to usage of the considered spa waters.

Estimation of the soil strength parameters in Tertiary volcanic regolith (NE Turkey) using analytical hierarchy process

Costly and time consuming testing techniques and the difficulties in providing undisturbed samples for these tests have led researchers to estimate strength parameters of soils with simple index tests. However, the paper focuses on estimation of strength parameters of soils as a function of the index properties. Analytical hierarchy process and multiple regression analysis based methodology were performed on datasets obtained from soil tests on 41 samples in Tertiary volcanic regolith. While the hierarchy model focused on determining the most important index properties affecting on strength parameters, regression analysis established meaningful relationships between strength parameters and index properties. The negative polynomial correlations between the friction angle and plasticity properties, and the positive exponential relations between the cohesion and plasticity properties were determined. These relations are characterized by a regression coefficient of 0.80. However, Terzaghi bearing capacity formulas were used to test the model. It is important to see whether there is any statistically significant relation between the calculated and the observed bearing capacity values for model testing. Based on the model, the positive linear correlation characterized by the regression coefficient of 0.86 were determined between bearing capacity values obtained by direct and indirect methods.

Influences of petrographic and textural properties on the strength of very strong granitic rocks

In this study, the petrographic characteristics affecting the strength of granitic rocks were investigated and a new mineralogical-based model was suggested for the prediction of uniaxial compressive strength (UCS) in line with the obtained data. Increase in quartz and alkali feldspar contents with decrease in plagioclase content partially increase the strength of granitic rocks. However, the results of modal analyses show that the rate of physically competent minerals do not directly affect strength of the granitic rock because the mineral size has a greater effect on strength than that of mineral type. The higher strength values were determined for the rocks containing monotype mineral in terms of size and quantity. In the scope of the study, significant relationships with a 0.89 correlation coefficient between UCS values and the Quality Index values (QI) were determined using mineral percentages, content and size. Because the modal analysis technique is a time-consuming process, ultrasonic velocity ratio (UVR) was defined in order to evaluate rock strength in the study and significant relationships were found with the correlation coefficient of 0.77 between UVR and QI. To estimate UCS using only ultrasonic wave velocity, it was determined whether there is a statistical relationship between UVR and UCS. The test result shows significant relation was found characterized with correlation coefficient of 0.84 value. UCS values obtained from the proposed equation and experimental studies were compared to test the suggested model; the results of the study showed that UCS values can be predicted without needing modal analysis with the new method proposed.