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Clayey sand can be considered as a composite matrix of coarse and fine grains. The interaction between coarser and finer grain matrices affects the overall stress–strain behavior of these soils. Intergranular void ratio, es (which is the void ratio of the coarser grain matrix) can be utilized as an alternative parameter to express the compressive response of such soils. Oedometer tests conducted on reconstituted kaolinite–sand mixtures indicate that initial conditions, percentage of fines, and stress conditions influence the compression characteristics evidently. Tests showed that, up to a fraction of fines, which is named as transition fines content (FCt), compression behavior of the mixtures is mainly controlled by the sand grains. When concentration of fines exceeds FCt, kaolinite controls the compression. It was found that FCt varies between 19% and 34% depending on the above mentioned factors. This range of fines content is also consistent with various values reported in literature regarding the strength alteration. Performed direct shear tests revealed that there is also a close relationship between transition fines content and shear strength, which is harmonic with the oedometer test results. 相似文献
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Suha Ozden Semir Over Kaan Sevki Kavak Serife Sevinc Inal 《Journal of Geodynamics》2008,46(1-2):48-62
This study defines the Late Cenozoic stress regimes acting around the Bolu Basin along the North Anatolian Fault in northwestern Turkey. The inferred regional stress regime, obtained from the inversion of measured fault-slip vectors as well as focal mechanism solutions, is significant and induces the right-lateral displacement of the North Anatolian Fault. The field observations have also revealed extensional structures in and around the Bolu Basin. These extensional structures can be interpreted as either a local effect of the regional transtensional stress regime or as the result of the interaction of the fault geometries of the dextral Duzce Fault and the southern escarpment of the North Anatolian Fault, bordering the Bolu Basin in the north and in the south, respectively.The inversion of slip vectors measured on fault planes indicates that a strike-slip stress regime with consistent NW- and NE-trending σHmax(σ1) and σHmin(σ3) axes is dominant. Stress ratio (R) values provided by inversion of slip vectors measured on both major and minor faults and field observations show significant variations of principal stress magnitudes within the strike-slip stress regime resulting in older transpression to younger transtension. These two stress states, producing dextral displacement along NAF, are coaxial with a consistent NE-trending σ3 axis. The earthquake focal mechanism inversions confirm that the transtensional stress regime has continued into recent times, having identical horizontal stress axis directions, characterized by NW and NE-trending σ1 and σ3 axes, respectively. A locally consistent NE-trending extensional, normal faulting regime is also seen in the Bolu Basin. The stress-tensor change within the strike-slip stress regime can be explained by variations in horizontal stress magnitudes that probably occurred in Quaternary times as a result of the westward extrusion of the Anatolian block. 相似文献
4.
Black Sea coast line is a hazardous region especially in winter due to the dominant wave action. Therefore, rubble mound breakwaters protected with armourstone used as ship shelters are vital structures especially for the fishermen. The deterioration of the armourstone with time in the form of abrasion and disintegration may result in the failure of the breakwater. In this study, the properties of the armourstone taken from an andesite quarry and used in the Hisarönü rubble mound breakwater were studied both in field and laboratory in order to assess their qualities and long-term durabilities. Based on the in situ observations and laboratory tests, the andesite is found to be generally marginal rock. CIRIA/CUR, RDIs, RERS and Wet-Dry strength ratio classifications are in good agreement with the in situ observations and the results of the laboratory tests. However, RDId, Average Pore Diameter and Saturation Coefficient classifications cannot correctly predict long-term durability of the armourstone. Field studies reveal that block size of the andesite in the quarry increases with depth due to the increase in spacing of the cooling joints of the rock. 相似文献
5.
Estimating compaction parameters of fine- and coarse-grained soils by means of artificial neural networks 总被引：2，自引：2，他引：0
This paper presents artificial neural network (ANN) prediction models for estimating the compaction parameters of both coarse- and fine-grained soils. A total number of 200 soil mixtures were prepared and compacted at standard Proctor energy. The compaction parameters were predicted by means of ANN models using different input data sets. The ANN prediction models were developed to find out which of the index properties correlate well with compaction parameters. In this respect, the transition fine content ratio (TFR) was defined as a new input parameter in addition to traditional soil index parameters (i.e. liquid limit, plastic limit, passing No. 4 sieve and passing No. 200 sieve). Highly nonlinear nature of the compaction data dictated development of two separate ANN models for maximum dry unit weight (γdmax) and optimum water content (ωopt). It was found that generalization capability and prediction accuracy of ANN models could be further enhanced by sub-clustered data division techniques. 相似文献
6.
In recent years, there has been increasing interest in the significance of natural radionuclides, particularly (210)Po, in the marine environment. (210)Po, a naturally occurring alpha emitter, accumulates in marine organisms and reflects differences in their diets. In the literature, there is no data for (210)Po and (210)Pb activity concentrations for fish species on the Turkish coast of Aegean Sea. Therefore, in this study, multiple fish species were collected from six stations seasonally on the Turkish coast of Aegean Sea and were analyzed for their (210)Po and (210)Pb content. The (210)Po and (210)Pb concentrations in the fish samples were found to vary from undetectable levels to 499 ± 44 Bq kg(-1) dry weight (dw) and from 1.0 ± 0.3 Bq kg(-1) to 35 ± 4.0 Bq kg(-1) (dw), respectively. There were no significant differences in the activity concentrations of (210)Po and (210)Pb in fish samples between seasons (ANOVA, P>0.05). The highest dose contribution of (210)Po to humans was calculated to be 10,530 μSv year(-1). 相似文献
7.
This study defines the Mio-Pliocene to present-day stress regime acting at the northeastern corner of the eastern Mediterranean region along the Karasu Valley (i.e., the Amanos Range), taking in the Antakya, Osmaniye and Kahramanmaras provinces. The inversion slip vectors measured on fault planes and chronologies between striations indicate that the stress regime varied from transpressional initially to transtensional, having consistent NW- and NE-trending σHmax (σ1) and σHmin (σ3) axes, respectively; there are significantly different mean stress-ratio (Rm) values however. The older mean stress state is characterized by N151±11°E-trending σ1 and N59±12°E-trending σ3 axes, and by a mean arithmetic Rm value of 0.76, indicating that the regional stress regime is transpressional. The younger stress regime is characterized by N154±8°E-trending σ1 and N243±8°E-trending σ3 axes, and by a mean arithmetic Rm value of 0.17, indicating a transtensional character for this regional stress regime. The low R values of the stress deviators related to the recent stress state reflect normal-component slips. The earthquake focal mechanism inversions confirm that the younger stress regime continues into the Recent. The inversion identifies a transtensional stress regime representing strike-slip and an extensional stress state with a consistent NE-trending σHmin (σ3) axis. These stress states are characterized by N66°E and N249°E-trending σ3 axes, respectively. Both significant regional stress regimes induce left-lateral displacement along the southern part of the East Anatolian Fault (EAF, or Amanos Fault). The temporal change, probably in Quaternary time, within the regional stress regime—from transpression to transtension—resulted from the coeval influences of subduction processes in the west–southwest (i.e., along the Cyprus arc), continental collision in the east, and westward escape of the Anatolian block. 相似文献
8.
Semir Over Suha Ozden Ulvi Can Unlugenc Huseyin Yılmaz 《Comptes Rendus Geoscience》2004,336(1):93-103
Fault kinematic analysis and inversion of focal mechanisms of shallow earthquakes reveal significant evolution of the regional stress regime in the northeastern most corner of the Eastern Mediterranean region since the Mio-Pliocene to the present time. This study was carried out in the interaction area between the Arabian/African plates and the Anatolian block. The evolution of stress regimes consists of a change from older transpression to younger transtension. Both strike-slip stress regimes having a NNW- to northwest-trending σHmax (σ1) and ENE- to northeast-trending σHmin (σ3) axes induce a sinistral component of displacement on the major intra-continental Karatas–Osmaniye and Misis–Ceyhan faults elongated with the northeast-trending Misis Range between Adana and Osmaniye provinces (sub-area i) and by a NNE-trending plate boundary Amanos fault running along Amanos Range between Antakya and Kahramanmaras provinces (sub-area ii). The inversion results show that the transtensional stress regime is dominantly strike-slip to extension, with an ENE- to northeast-trending σHmin (σ3) axis for sub-areas (i) and (ii), respectively. The inversions of earthquake focal mechanisms indicate that the transtensional stress regime is still active in the whole study area since probably recent Quaternary time. To cite this article: S. Over et al., C. R. Geoscience 336 (2004). 相似文献
9.
Engineering characteristics of Ankara Greywacke under the foundation of the Beytepe open air theatre,Ankara, Turkey 总被引：1，自引：0，他引：1
The construction of a large open air theatre having with an audience capacity of 7,000 is planned at the Beytepe Campus of
Hacettepe University located near Ankara, Turkey, in the heart of Anatolia. The foundation of the open air theatre is composed
of weak and heavily jointed Ankara Greywacke. An estimation of the strength and deformation of the Ankara Greywacke was required
for assessments of short- and long-term stability. Accordingly, rock mass characterization of the Ankara Greywacke was investigated
in detail by scan-line surveys and back-analyses of in situ tests performed on the excavated surface of the rock mass. The
final version of the Hoek and Brown Criterion (Hoek et al., In: Proceedings of the north American rock mechanics society meeting,
Toronto, Canada, pp 1–6, 2002) together with and improvements proposed by Sonmez and Gokceoglu (Int J Rock Mech Min Sci, 43:671–676,
2006) were considered together for the back analyses of small slope benches subjected to plate loading test loaded to failure.
In addition, the plate loading test data were used with some well-known empirical equations for predicting of deformation
modulus of rock masses to calculate ranges of values of the Geological Strength Index (GSI) The static and pseudostatic slope
stabilities of the audience seating structures to be supported by benches excavated into the rock were also analyzed. The
stability assessments revealed the unlikelihood of large rock mass failures for the short-term construction stages or for
the long-term, as-constructed conditions under static or pseudo-static conditions. Additionally, the analyses showed that
there was no need for anchors between the concrete seating structures and greywacke rock mass. 相似文献
10.
Assessment of rockfall hazard around Afyon Castle,Turkey 总被引：2，自引：0，他引：2
The Afyon Castle is a tourist destination and a historical site in the City of Afyon in Turkey. The Castle is located on a
steep hill, with a height of 226 m. In close proximity to the Castle there are settlements. The hill consists of trachitic
andesite. The rock contains columnar joints and flow layering. Owing to these discontinuities, blocks of varying sizes had
fallen down. The settlement areas near the Castle are now in danger because of the rockfall risk. In this study, rockfall
analysis was carried out along nine profiles of the hill. Fall-out distance, bounce height, kinetic energy and velocity of
the rocks along each profile were investigated. The results of the analyses were evaluated, and the areas delineated as susceptible
to rockfall risk are highlighted. Remedial measures including rock bolts and protective fences were suggested on the basis
of the field observations and the rockfall risk evaluation. 相似文献