Insight into the effects of clay mineralogy on the cyclic behavior of silt–clay mixtures

Results of a systematic testing program showed that the cyclic behavior of silt–clay mixtures is greatly influenced by the dominant clay minerals in the mixture. In particular, it was demonstrated that given the same amount of clay/clay mineral and/or same value of plasticity index, the montmorillonitic soils have the highest cyclic strength, followed by the illitic soils, and then by the kaolinitic soils. Moreover, the rate of increase in cyclic strength with increasing % clay mineral and PI is again the highest in the montmorillonitic soil, lowest in the kaolinitic soil and intermediate in the illitic soil. Therefore, without considering clay mineralogy, the % clay fraction, % clay mineral and plasticity index are unreliable indicators of the liquefaction susceptibility of fine-grained soils. The differing adhesive bond strength each clay mineral develops with the silt particles is deemed to largely explain the observed differences in the response of the three different soil mixtures to cyclic loading.     

Assessment and analysis of rockfall-caused tree injuries in a Turkish fir stand: A case study from Kastamonu-Turkey

Rockfalls can cause serious damage to people,property,facilities and transportation corridors.Furthermore,rockfalls are major hazards in mountain areas with negative impacts on individual trees and forested ecosystems.We conducted a study of rockfall events on 117 mapped(91% of total trees in the stand with1.3 m in height and5 cm diameter at breast height)Turkish fir trees(Abies bornmuelleriana Mattf.)in a stand within the Kayaarkasi-Topular Village,Inebolu district, Kastamonu province of Turkey.The study site of 0.35 Ha is located on the transition zone of frequently passing rockfall fragments(～40 cm in diameter) generally causing healable injuries.Parameters of trees and injuries were recorded and analysed as to injury number,height and size.Bivariate correlation analysis were used to investigate the relationships between:a)diameter at breast height and number of injuries per tree,b)diameter at breast height and total injury size,c)the number of injuries and total injury size and d)the number of injuries per tree and distance from the source of the rockfall area.Results indicate that the average height of injury,average number of injuries and average injury area to be 81.3 cm(STDEV:49.8),7.46(STDEV:4.4)and 628.6 cm2 (STDEV:678.2),respectively.In total 84% of all injuries were recorded within 160°sector at the upslope side of trees and callus tissue that had closed wounds was observed in 79.1% of all injuries. Furthermore 14.5% of injured trees had callus tissue in the process of closing wounds while 6.4% of injuries had not formed any callus tissue.The most common injury types were bark and wood injuries. Bivariate correlation analysis indicated strong relationships between diameter at breast height and the number of injuries(rs=0.524),injury number and total injury area(rs=0.653)and distance from rockfall area and injury numbers relations(rs=-0.518).A weaker relationship was found between diameter at breast height and total injury area(rs=0.363).These results indicate that bigger trees are more prone to rockfall injuries.As expected,trees further from the rockfall area seem to be less prone to rockfall injuries.From our results,it can be inferred that the protection of people and property can be increased through the maintanance of forest in areas immediately below areas prone to rockfall.This stand is still managed in selective forest management system.In order to protect the settlement at the deposition zone it has to manage for protective goals with uneven-aged and multilayered stand structure.     

Probabilistic evaluation of observed earthquake damage data in Turkey

Empirical, theoretical or hybrid methods can be used for the vulnerability analysis of structures to evaluate the seismic damage data and to obtain probability damage matrices. The information on observed structural damage after earthquakes has critical importance to drive empirical vulnerability methods. The purpose of this paper is to evaluate the damage distributions based on the data observed in Erzincan-1992, Dinar-1995 and Kocaeli-1999 earthquakes in Turkey utilizing two probability models—Modified Binomial Distribution (MBiD) and Modified Beta Distribution (MBeD). Based on these analyses, it was possible (a) to compare the advantages and limitations of the two probability models with respect to their capabilities in modelling the observed damage distributions; (b) to evaluate the damage assessment for reinforced concrete and masonry buildings in Turkey based on these models; (c) to model the damage distribution of different sub-groups such as buildings with different number of storeys or soil conditions according to the both models. The results indicate that (a) MBeD is more suitable than the MBiD to model the observed damage data for both reinforced concrete and masonry buildings in Turkey; (b) the sub-groups with lower number of stories are located in the lower intensity levels, while the sub-groups with higher number of stories depending on local site condition are concentrated in the higher intensity levels, thus site conditions should also be considered in the assessment of the intensity levels; (c) the detailed local models decrease the uncertainties of loss estimation since the damage distribution of sub-groups can be more accurately modelled compared to the general damage distribution models.     

Evaluation of parameters affecting earthquake damage by decision tree techniques

Earthquake damages are assessed based on a holistic approach using structural as well as non-structural factors to model earthquake damage distributions with Decision Tree Techniques, using the Answer Tree program and the damage data from recent major earthquakes in Turkey. The damage dataset consists of approximately 9,400 buildings that were surveyed to evaluate the factors affecting building damage after Erzincan [1992], Dinar [1995], and Kocaeli [1999] earthquakes. The earthquake damage is defined as the dependent variable, while earthquake magnitude (M), intensity (I) in the city, peak ground acceleration (PGA) in each city, epicenter distance (ED), building types (BT), number of storeys (NS), presence of soft storey (SS), building position (BP) on the site, and site conditions (SC) are independent variables in the proposed model. The damage level (DL) was classified with respect to red, yellow, and green codes. The main purpose was (1) to identify the factors controlling building damage during earthquakes; (b) to determine the most significant factor; (c) to evaluate the effects of different factors for different earthquakes; (d) to develop damage distribution models for different subgroups based on the Decision Tree Techniques.