• Earthquakes and Structures
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• v.14 no.6
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• pp.615-626
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• 2018

The seismic vulnerability of Turkey is relatively high due to its active fault systems with potential to create destructive earthquakes. Thus, reducing the loss of life and property, the number of the earthquake-prone buildings and their retrofit requirements are considerably significant key issues under the scenario earthquakes. The street survey based rapid assessment (SSRA) method can be considered as a powerful tool to determine the seismic vulnerability of building stock of an earthquake-prone city/state. In this study, the seismic vulnerability of the building stock of the Kirikkale province in Turkey is aimed to be estimated adopting the street survey based rapid assessment method (SSRA). For this purpose, central 2074 existing reinforced concrete (R/C) buildings were structurally surveyed with rapid visual site screening and disadvantages such as, the existence of short-column, soft-story, heavy overhangs, pounding effect and local soil conditions were determined for obtaining the structural performance score of each. The results obtained from the study demonstrate that 11-25% of the surveyed buildings in the study region needs to be investigated through more advanced assessment methods. Besides, higher correlation between increasing story number and unsafe/safe building ratio is obtained for the buildings with soft-story parameter than that for those with heavy overhangs and short-column parameters. The conformity of the results of the current study with the previous documented cases of rapid assessment efforts in the recent earthquakes in Turkey shows that the SSRA method for the Kirikkale province performed well, and thus this methodology can be reliably used for similar settlement areas.

• Geotechnical Engineering
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• v.3 no.1
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• pp.39-52
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• 1987

Model pile tests are performed, first, to estimate donwndrag exerted on pile surfaces due to the settlement of surrounding soils, and, second, to evaluate the efficiency of the downdrag reduction methods such as the bitumen coating method and the method of the attachment of an enlarged base. Test results show that the downdrag forces may be expressed as 0.25(;effective overburden). Bitumen coating reduces the downdrag by more than 50 percent, and the enlarged base attachment method is also effective, whose effectiveness increases as the sixte of the base increases as expected. When the bitumen coating and enlarged base are both applied, the downdrag force is reduced as much as 90 percent. Finally, it is found that the quantity of the relative displacement between the pile and the surrounding soil downdrag is extremely small.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.1148-1155
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• 2010

To suggest a modified shallow foundation design method which can be considered the scale effect of foundation on IGM(intermediate geomaterial) soil layer, the weathered soil layer that is uniformly formed up to 8m(2B) with over 50 N-value is selected and 3 times field loading tests are performed on several sized square-shaped shallow foundations with 30, 75, 150, 240 and 400cm in width respectively. Because the soil modulus of elasticity(Es) calculated by soil investigation and 1st field test(PBT) results showed an underestimated tendency, a modified correlation is required for the reasonable estimation of Es on the weathered soil. Also, the N-value was increased with an increasing in depth. However, the N-values around the test foundations showed the different values even though the foundations on the same level because the test site was arranged by excavation. Therefore, the more detail soil investigations are required for the each test foundations respectively. Since Es based on elasticity theory is determined by the stress distribution shape of the foundation and elasticity modulus of the soil, the scale effect considered pressure-settlement curve can be clearly derived from the correlation on stress distribution shape and the variation of soil elasticity modulus with depth. Therefore, the modified correlation will be suggested to estimate a reasonable Es on the weathered soil, and the scale effect considered shallow foundation design method is also developed based on the elastic theory and field tests in this research.

• Geotechnical Engineering
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• v.8 no.4
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• pp.5-16
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• 1992

The main purpose of this the sutdy is to develop the reinforced earth structure design method considering induced stresses and deflections resulting from placement and compaction of soil. In this paper, the new reinforcement Geolog developed by the author is also introduced which is being used as one of the effective earth reinforcing structure against compaction induced stresses. This study adopted the Seed's bilinear model in the estimation of the com paction induced stresses and compute the peak lateral stresses during compaction by doubled Boussinessq's elastic solution of mirror image theory, thereafter, calculate the residual compaction induced lateral stresses from the above peak lateral stress by the residual fraction. It is considered to be reasonable that the compaction induced stresses be added to the lateral earth pressures estimated from conventional gravity analysis considering the actual stresses during service life of the structures. "GEOLOG", a composite of steel bar and attached concrete stopper is found to be effective against tension and pull - out failure. In this paper, the design method considering the compaction induced stresses and the effect of Geolog reinforcement is suggested for the remforced earth structures where backkfill settlement on displacements are not allowed as in the cases of the bridge abutments or double faced reinforcement earth structures.tructures.

• Korean Journal of Agricultural Science
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• v.25 no.2
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• pp.260-270
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• 1998

The field tests were performed to suggest the rational method for stability evaluation of soft clay. The behavior of settlement-displacement obtained by field monitoring system was to compare and analyze the results of the observationed method, and to investigate the complex behavior of soft clay with filling height. The results of this study are summarized as follows. 1. The horizontal displacement was suddenly increased when physical properties of soft clay showed maximum values and the part of the turning point. The values of these properties were available to the fundamental data for stability evaluation. The shear deformation appeared that difference of the horizontal displacement was maximum values. 2. Although the stability of embankment by step filling showed the unstable part over the failure standard line, the embankment was confirmed stable. So the evaluation of the stability of embankment is reasonable to use the inclination of curve than failure standard line. 3. The horizontal displacement and relative settlement were increased as same ratio at improvement ground. Estimation of shear deformation using Terzaghi's modified bearing capacity should consider the relations of embankment load and undrained shear strength at nonimprovement ground, and minimum safety factor is recommended to use larger than 1.2. 4. Excess pore water pressure was increased with increasing of filling height and decreased with maintain the filling height. The embankment was unstable when filling height was exceed the evaluation standard line, and the behavior of excess pore water pressure and horizontal displacement could use as a standard of judgement of the filling velocity control because their behavior were agree with each other.

• Journal of the Korean Geotechnical Society
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• v.15 no.1
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• pp.161-173
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• 1999

Settlement analysis based on oedometer test results with or without Skempton-Bjerrum's modification method ( widely used for practical purposes when estimating consolidation settlements of soft clay deposits) has shortcomings that it cannot simulate real stress states and deformation behaviors of soils in case that in-situ loading and deformation conditions are not 1-dimensional. In this study, the stress path method, reflecting various probable stress paths, was employed to normally - consolidated kaolinite samples by using automated triaxial testing device which can control stress paths automatically. From this experimental study, elastic, consolidation, secondary compression and pore pressure development - dissipation behaviors under various stress paths were analyzed and deformation characteristics of soft clays, which can be the basis of rational estimation of settlements, were studied. Also by comparing results of stress path tests with those of 1-dimensional consolidation tests, limitations and problems of conventional methods were clarified.

• Journal of the Korean GEO-environmental Society
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• v.3 no.1
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• pp.67-77
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• 2002

Volume change of the dredged soils is composed of the volume loss of soil particle flowing over an outflow weir with water and settlement due to both the self-weight consolidation in reclaimed layer and the desiccation at the surface of reclaimed layer. In order to estimate the amount of soil particles flowing over an outflow weir with water, the evaluation procedure of loss ratio of the dredged soils is proposed in the present study based on the Marsal's modified breakage theory and the results of hydrometer analyses. To verify a validity of the proposed procedure, evaluated loss ratio is compared with results from the other existing methods. The model test results and those of field test were compared and analyzed. Also, the variation of soil loss ratio was examined through the model test in the lab.

• Journal of the Korean Geotechnical Society
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• v.27 no.9
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• pp.13-24
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• 2011

The renowned Terzaghi's one-dimensional consolidation theory is not applicable to quantification of time-rate settlement for highly deformable soft clays such as dredged soil deposits. To deal with this special condition, a non-linear finite strain consolidation theory should be adopted to predict the settlement of dredged soil deposits including self-weight and surcharge-induced consolidation. It is of importance to determine the zero effective stress void ratio ($e_{00}$), which is the void ratio at effective stress equal to zero, and the relationships of void ratio-effective stress and of void ratio-hydraulic conductivity for characterizing non-linear finite strain consolidation behavior for deformable dredged soil deposits. The zero effective stress void ratio means a transitional status from sedimentation to self-weight consolidation of dredged soils. In this paper, laboratory procedures and equipments are introduced to measure such key parameters in the non-linear finite strain consolidation analysis. In addition, the non-linear finite strain consolidation parameters of the Incheon clay and kaolinite are evaluated with the aid of the proposed methods in this paper, which will be used as input parameters for the non-linear finite strain consolidation analyses being performed in the companion paper.

• Journal of the Korean Geotechnical Society
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• v.17 no.6
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• pp.181-191
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• 2001

Granular compaction piles increase the load bearing capacity of the soft ground and reduce the settlement of fecundation built on the reinforced soil. Also the granular compaction piles accelerate the consolidation of soft ground using the granular materials such as sand, gravel, stone etc. However, this method is one of unuseful methods in Korea. In the present study, the estimation procedure for the ultimate bearing capacity of randomly installed granular compaction pile group is proposed. Also, carbon rod tests have been peformed for verifying the group effect of granular compaction piles and the behavior characteristics such as bulging failure zone on granular compaction piles. From the test results, it is found that bulging failure shape of granular compaction piles was conical shape and the ultimate bearing capacity increased as the spacing of piles became gradually narrow. Also, from the proposed method in this study, the optimal locations of granular compaction piles with various installed cases are analyzed. The results were shown that the bearing capacity was increased in the case concentrated on the central part of pile group.

• Journal of the Korean GEO-environmental Society
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• v.16 no.1
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• pp.5-16
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• 2015

In the long span bridge construction, construction cost portion of large scale marine foundation is about 40% (KICTEP, 2007). In this study, designs for deep water depth large composite foundation of a super long span cable-stayed girder bridge of prototype were performed by three design methods (ASD, LRFD, Eurocode) and the behaviors of a large diameter drilled shaft were analyzed and the 3D numerical analysis was performed. As a result, the soft rock socket lengths in allowable stress design estimation method were the longest. The soft rock socket lengths estimated by the design approach 2 among Eurocode and the LRFD were similar. The longer the socket length socketed in the soft rock was, the smaller the axial force acting on a large-diameter drilled shaft head was and the smaller the settlement of drilled shaft was.