Mehmet Berilgen

A case study of seismic zonation in municipal areas

An earthquake of 7.4 magnitude in August 1999 caused major loss of life and severe damage within the municipality of Izmit, 170 km southeast of Istanbul (Figure 1). A survey of the damaged buildings was made by the municipal authorities shortly after the earthquake. The municipal government decided to conduct a pilot seismic zonation project to determine whether the cause of the damage was poor construction materials and methods or weak soil conditions. In this project, we investigated the soil conditions with two objectives in mind: (1) to estimate the seismic model of the soil column at each district to determine the geotechnical earthquake engineering parameters, and (2) to map active faults within the municipal area.

Seismic, Geotechnical, and Earthquake Engineering Site Characterization

Summary We determined the seismic model of the soil column within a residential project site in Istanbul, Turkey. Specifically, we conducted refraction seismic survey at 20 locations and estimated the P- and S-wave velocity-depth profiles down to a depth of 30 m. We then combined the seismic velocities with the geotechnical borehole information regarding the lithology of the soil column and determined the site-specific geotechnical earnthquake engineering parameters for the site. Specifically, we computed the maximum soil amplification ratio, maximum surfacebedrock acceleration ratio, depth interval of significant acceleration, maximum soil-rock response ratio, and design spectrum periods TA-TB.

Determination of consolidation behaviour of Haliç dredged material by using a seepage‐induced consolidation test

Purpose – To establish relationships between effective vertical stress‐void ratio and hydraulic conductivity‐void ratio on high water content dredged clays, which are then used to predict the field consolidation behavior.Design/methodology/approach – The large strain consolidation model is used for numerical modeling of large‐strain self‐weight consolidation. Material parameters determined from seepage‐induced consolidation tests provided satisfactory predictions of field compression behavior.Findings – It is shown that realistic estimates of self‐weight consolidation behavior of dredged sea bottom sediments stored on land can be made by using a seepage‐induced consolidation test system and an appropriate consolidation model such as CS2, which is very important in storage capacity design and reclamation planning of such storage areas.Originality/value – In this paper, the findings are presented of an experimental investigation of the consolidation behavior of Golden Horn dredge material using a seepage‐in...

Construction of Earth Dams on Soft Ground: Principles and Examples

In areas where river sediments are thick, construction of earth dams by excavating these sediments and replacing with compacted fill causes significant cost increases. River sediments consists of, in terms of soil mechanics, either granular (sand, gravel) or fine-grained (silt, clay) materials. Granular sediments can be improved with relative ease against instability and compressibility; however, because such deposits are highly permeable, additional measures are required to prevent seepage loss through the dam foundation. Fine-grained deposits, if they do not contain extensive sand or gravel lenses, offer fewer problems relative to seepage loss and may not require seepage control measures. However, such materials typically have low strength and high compressibility and present stability and settlement concerns. The objective of this article is to present examples of earth dams founded directly over fine-grained river sediments. Available methods for improvement of highly compressible, low strength deposits are limited. Staged construction (although it is time-consuming, it can be accelerated to reasonable levels with prefabricated vertical drains) and column-supported earth fill (although more expensive it enables accelerated construction) can be cited as two main approaches for this purpose. Because it is generally more economical, the design principles of staged construction and the relevant methods of analysis are presented herein. Alibey Dam for slow staged construction and Hamzadere dam (not yet constructed) for accelerated staged construction are cited as examples of this approach. The results of analyses and observations indicate that earth dams can be constructed directly on soft fine-grained river sediments with appropriate ground improvement.