Fikri Bulut

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.

Determination of discontinuity traces on inaccessible rock slopes using electronic tacheometer: an example from the İkizdere (Rize) Region, Turkey

Abstract Discontinuity traces on inaccessible steep rock slopes cannot be measured in detail by means of conventional techniques. However, because the data obtained from discontinuity traces are used as parameters in engineering projects such traces must be determined precisely. This study shows that discontinuity traces on inaccessible rock slopes can be studied in detail by means of a recently developed computerised electronic tacheometer (total station) and shows a field application.

Geoenvironmental evaluation for planning: an example from Gumushane City, close to the North Anatolia Fault Zone, NE Turkey

The paper highlights the importance of establishing an appropriate database of information to assist planners in site selection and decisions regarding land usage. Such a database should include geological and geotechnical information, but this should be assessed from a geoenvironmental viewpoint. The city of Gumushane in the Black Sea region is discussed, as this area is close to the North Anatolia Fault Zone and there is a shortage of “suitable” ground for development.RésuméL’article souligne l’intérêt d’une base de données appropriée pour aider les planificateurs dans leurs décisions d’aménagement de l’espace. Une telle base de données devrait contenir des informations géologiques et géotechniques et devrait être établie avec un point de vue géo-environnemental. La ville de Gumushane dans la région de la Mer Noire est considérée. Elle est proche de la faille nord-anatolienne et il y a une pénurie de terrains pour le développement de cette région.

Understanding the mechanism of slope failure on a nearby highway tunnel route by different slope stability analysis methods: a case from NE Turkey

The Arakli tunnel is located in the eastern Black Sea region where the most mass movement is observed in Turkey. Following the tunnel entrance portal excavations in basaltic tuffs on nearby the Konakonu residential area, an impending failure occurred. Because of the developed tension cracks and deformations on the ground, five houses and their gardens were damaged completely. The present study aims to investigate the mechanism of the failure. In order to do this, kinematic, limit equilibrium, and numerical stability analyses were carried out. Firstly, the kinematic analyses were performed taking into account the main joint sets for the slopes. The results of the kinematic analyses showed that planar and wedge failures were possible on the portal slope and no failure occurred on the cut slope. However, the limit equilibrium analysis showed that neither the planar nor wedge failures were expected to occur on the portal slope. The numerical stability analyses were performed to determine if circular failure is to occur in the slopes. The Phase2 programme was used in the numerical analyses, and the Strength Reduction Factors (SRF) of the slopes were determined. According to the numerical stability analyses, the failure mode for the portal slope is composite starting with a circular surface and following a linear surface and circular for the cut slope. The stability analyses indicated that the failure mechanism was not directly controlled by the joints and might be related to the low strength parameters of the rock mass and joints. Finally, precautions were determined to make the region stable using the Phase2 programme. After support installation, the SRF values for the portal and cut slopes increased from 1.21 to 1.63 and from 1.32 to 1.71, respectively. These results showed that the proposed support units prevent the effects of failure and were essential for the long-term stability.

A NEW APPROACH TO THE EVALUATION OF WATER-PRESSURE TEST RESULTS OBTAINED IN BEDROCK BY THE US BUREAU OF RECLAMATION METHOD

Abstract As is known, the permeability coefficient of saturated and unsaturated rock masses can be found using the Bureau of Reclamation Method, which uses single and double packer water-pressure test results obtained from drillholes. The Bureau of Reclamation Method is, however, a time-consuming processes. In this study, a new graphical method that does not necessitate the procedures mentioned above is proposed for the determination of the coefficient of permeability. This graphical method has been prepared with the idea that the amount of water injected into the testing section increases as the permeability of the rock mass increases. If the amount of average water loss in a 2-m test section is known, the average permeability coefficient of this section can be found using the proposed graphical method.

Bearing capacity and slope stability assessment of rock masses at the Subasi viaduct site, NE, Turkey

This study investigates the bearing capacity of rock masses and stability of slopes at the Subasi viaduct site which is a part of the improvement project of the Artvin–Hopa government highway between KM 6 + 500 and 13 + 787 in NE Turkey. The geotechnical studies were performed in three stages. Firstly, the bearing capacity of moderately weathered andesitic tuff was evaluated using the empirical equations. Secondly, the major principal stress and vertical displacement due to the viaduct and traffic loadings at the level of foundations were determined by the finite element method (FEM). The vertical displacement value and comparison of bearing capacity and major principal stress show that any problem is not expected at the viaduct site in terms of the bearing capacity. Finally, the stability of slopes at the viaduct site was investigated using kinematic, limit equilibrium, and finite element method-based shear strength reduction analyses methods. It was concluded that no discontinuity controlled failures at the slopes are expected. However, a circular failure is possible to occur at the face slope excavated in highly weathered andesitic tuff. After support application, the long-term stabilization of face slope has been achieved. Consequently, it is suggested that the empirical, analytical, and numerical methods should be combined for a more reliable construction design.

Geotechnical investigations and remediation design for failure of tunnel portal section: a case study in northern Turkey

Mass movements are very common problems in the eastern Black Sea region of Turkey due to its climate conditions, geological, and geomorphological characteristics. High slope angle, weathering, dense rainfalls, and anthropogenic impacts are generally reported as the most important triggering factors in the region. Following the portal slope excavations in the entrance section of Cankurtaran tunnel, located in the region, where the highly weathered andesitic tuff crops out, a circular toe failure occurred. The main target of the present study is to investigate the causes and occurrence mechanism of this failure and to determine the feasible remedial measures against it using finite element method (FEM) in four stages. These stages are slope stability analyses for pre- and postexcavation cases, and remediation design assessments for slope and tunnel. The results of the FEM-SSR analyses indicated that the insufficient initial support design and weathering of the andesitic tuffs are the main factors that caused the portal failure. After installing a rock retaining wall with jet grout columns and reinforced slope benching applications, the factor of safety increased from 0.83 to 2.80. In addition to slope stability evaluation, the Rock Mass Rating (RMR), Rock Mass Quality (Q) and New Austrian Tunneling Method (NATM) systems were also utilized as empirical methods to characterize the tunnel ground and to determine the tunnel support design. The performance of the suggested empirical support design, induced stress distributions and deformations were analyzed by means of numerical modelling. Finally, it was concluded that the recommended stabilization technique was essential for the dynamic long-term stability and prevents the effects of failure. Additionally, the FEM method gives useful and reasonably reliable results in evaluating the stability of cut slopes and tunnels excavated both in continuous and discontinuous rock masses.