Tuğba Eskişar

Work-related injuries and fatalities in the geotechnical site works

Geotechnical site works are comprehensive, and they constitute the first step of the construction process. This study performs data mining of geotechnical works and analyzes the database for the root causes of accidents. The Occupational Safety and Health Administration (OSHA) was chosen for the 1984–2013 time frame with 247 cases. Descriptive statistical analyses were performed to discuss variables such as the end use of the work, project type and cost, soil type and condition, type and degree of injury, cause and type of accident, unsafe acts, and occupation and union status of the victim. The results showed that these accidents have a high frequency of recurrence and have a high severity level (54.3% fatalities). In addition, a total of 838 violations were recorded with penalties reaching 5 million US dollars. This study emphasizes that project-specific countermeasures should be taken regarding the root causes of accidents, leading to vigorous strategies to develop safety measures.

The Liquefaction Behavior of Poorly Graded Sands Reinforced with Fibers

This study focuses on the performance of fibers, improving the resistance to liquefaction in loose sands, medium sands, and dense sands in Izmir, Turkey. A systematic testing schedule consisting of cyclic triaxial tests was held under stress-controlled and undrained conditions on saturated sand specimens with and without fiber reinforcements. The major parameters having effects on the dynamic behavior such as fiber content, fiber length, and relative density on the liquefaction behavior and the excess pore water pressure developments of specimens with and without fibers were investigated. If the fiber content or the fiber length was increased in the specimens, higher number of loading cycles was needed in order to experience the liquefaction of sands. The reinforcement effect in medium-dense specimens was found to be apparently distinctive compared to loose specimens. The curves of pore water pressures and shear strains were achieved for the fiber-reinforced sands. The boundaries of pore water pressure curves presented in the literature on the clean sands were utilized in comparison with the pore water pressure curves of fiber-reinforced sands of this study. As a conclusion, the results presented in this study are useful to develop insight into the behavior of clean and fiber-reinforced sands under seismic loading conditions. Based on the test results, it was found that the number of loading cycles had a strong impact on the excess pore pressure generation.

Brief Overlook on the Occupational Accidents Occurring During the Geotechnical Site Works

The aim of this paper is to evaluate occupational accidents reported in geotechnical site works. Variables of the accidents are categorized as the year and month of accidents, the technical codes used for defining the scope of work trades, end use and project type and cost, nature and cause of accidents, occupation of the victims and finally the cause of fatality. As a result, it is seen that the majority of victims were construction laborers or in special trade constructors who were working on a new project or new additions to an existing project. The geotechnical phase of the projects was whether excavation, landfill, sewer-water treatment, pipeline construction, commercial building or road construction. As the outcomes of the study it is evaluated that excavation, trenching and installing pipe or pile driving were the main causes of the accidents while trench collapse, struck by a falling object / projectile and wall collapse were the main causes of fatality. Moreover, it is established that more than half of the fatalities were due to asphyxia followed by fracture. These findings show that accidents occurred in geotechnical works do not only have high frequency but also high severity. This study emphasizes project specific countermeasures should be taken regarding the nature, cost and importance of the project and the occupation variabilities working on the project.

Dynamic properties of soils in the northern coast of Izmir Bay area

In this study, dynamic properties of soils in the northern coast of Izmir Bay area are investigated by dynamic site response analyses and microtremor measurements. Fundamental periods of soil profiles that are obtained from both methods are compared. Variation of dynamic soil properties in the northern coast of Izmir Bay are investigated depending on the bedrock depth and heterogeneous soil structure in the site. Dynamic site response analyses based on equivalent-linear methodology have been performed for 50 borehole locations. Liquefaction analyses are also performed at borehole locations, liquefaction potential index is calculated, and level of liquefaction risk is determined. While the liquefaction risk is very low or none for the moderate scale earthquake (M=5.3), medium-high levels of liquefaction risk for the scenario earthquake magnitude (M=6.5) is found. Fundamental periods obtained from microtremor measurements and those calculated from dynamic analyses are close to each other. Fundamental periods vary in the range of 0.65-1.2 s depending on the bedrock depth in the study area. Fundamental period is higher where the bedrock depth increases.