Seismic failure probability of concrete slab on CFR dams with welded and friction contacts by response surface method     

Murat Emre Kartal  Alemdar Bayraktar  Hasan Basri Başağa 《Soil Dynamics and Earthquake Engineering》2010

In this study, failure probability of the concrete slab on concrete-faced rockfill (CFR) dams with welded and friction contact is investigated under earthquake effects by reliability analysis. For this purpose, Torul CFR dam is selected as an example and numerical solutions are performed by considering combination of reliability analysis–finite element method. 1992 Erzincan earthquake acceleration record is used in the finite element analysis considering deconvolved-base rock input model. In this model, the ground motion to be applied to the foundation base rock is obtained by deconvolution of the free-field surface record. In the materially nonlinear analysis, Drucker–Prager model is used for concrete slab and multi-linear kinematic hardening model is utilized for rockfill. Geometrically nonlinearity is also taken into account. Viscous boundary conditions are defined in the finite element model for both foundation soil and reservoir water. The hydrodynamic pressure of the reservoir water is considered using 2D fluid finite elements based on the Lagrangian approach. Both welded contact and friction contact based on the Coulomb’s friction law are defined in the structural connections. Improved Rackwitz–Fiessler method is used with response surface method in the reliability analysis. The tensile and compression strengths of the concrete slab are utilized in the implicit limit state functions considering various thicknesses. The probability of failure of the most critical points in the concrete slab is obtained. According to this study, the probabilities of failure obtained from the CFR dam including friction contact are lower. When the welded contact is considered in joints, the probability of failure of the concrete slab is 1 due to tensile stress limit state and compression stress limit state only if concrete slab is linear. The most critical probability of failure of the concrete slab appears in the case that the concrete slab is linear and rockfill is materially nonlinear. The probability of failure of the concrete slab decreases if the nonlinearity of the concrete is considered. Also, hydrodynamic pressure decreases the reliability of the concrete slab.  相似文献   

Linear and nonlinear response of concrete slab on CFR dam during earthquake     

Alemdar Bayraktar  Murat Emre Kartal 《Soil Dynamics and Earthquake Engineering》2010

The joint between concrete slab and rockfill is designed as welded contact in the classical modeling of concrete-faced rockfill (CFR) dams and earthquake response of the CFR dams is determined by this method. In this study, linear and nonlinear response of Torul CFR Dam including interface element between concrete slab and rockfill were investigated for the duration of strong seismic excitation. The finite element analyses were performed by employing both cases, empty and full reservoir, to research the effect of the reservoir water on the earthquake response of the dam. The reservoir water was modeled with fluid finite elements by the Lagrangian approach. The Drucker-Prager model was used in nonlinear analyses for concrete slab, rockfill and soil materials. According to finite element analyses, displacement and stress components were increased by hydrodynamic pressure. The nonlinear response of the concrete slab was monitored about the peak ground acceleration (pga). This study reveals that the size of sliding zone increases with increasing acceleration amplitudes.  相似文献   

Hydrological Properties of the Derme Karstic Springs by Using Hydrogeochemical Analyses and Environmental Isotope Techniques          下载免费PDF全文

Omer Faruk Dursun  Murat Celiker  Mahmut Firat 《洁净——土壤、空气、水》2016,44(2):143-153

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Geochemistry of the limestone of Mortas Formation and related terra rossa,Seydisehir, Konya,Turkey     

Sedat Temur  Hukmu Orhan  Arif Deli 《Geochemistry International》2009,47(1):67-93

The purpose of this study was to determine and evaluate the geochemical characteristics of the limestone of the Upper Cretaceous Mortas Formation and related terra rossa in a 50 km² area which is located 20 km south of the city of Seydisehir, Central Anatolia, by using data obtained from the ICP-MS analysis of randomly collected 42 samples of limestone and 18 samples of the terra rossa.The limestone of the Mortas Formation is composed of fossilliferous, gray-cream colored, medium to thick bedded, partially dolomitic carbonate rocks, and generally has dismicrite, intrapelmicrite composition. It includes the largest bauxite reservior in Turkey and has many occurences of terra rossa formation on it. According to mean distance, the Ba, Be, Hg, Mo, Nb, Sb and Th concentrations in the limestones overlying and underlying the bauxite deposits are different, but the main oxides, REE and other trace elements are same. In factor analysis, the first component reflects relative enrichment of clay against to CaO contents of the limestone, the second component corresponds to the degree of dolomitization. The PAAS-normalized REEs pattern for the Mortas Formation limestone samples illustrate similar main features as seawater.The terra rossa soils in the study area are considered to be highly weathered and weakly mature soil with respect to their generally low Al₂O₃ (21%), but high CaO (2%) contents, and their alteration indices. The element ratios in the terra rossa and limestone show that in the process of the transformation from limestone to terra rossa, Ba, Si, Ti, Al and Fe were enriched together by staying in-situ. Except Ce, all lanthanides show similar behavior, but the HREE, which were richer in limestone, were consumed fast relative to the LREE during soil formation. The association and the enrichment of Co, Cu, Cr, Ni and Pb as well as Ba, Zr, Ga, Nb and Rb in soil relative to the limestone are interpreted as being resulted from eolian transportation. Ca, Au, Hg, Sr, Se, Sb, Mo, Ag, U, Cd and Na were found to be the most mobile elements during pedogenic transformation. According to main oxide composition ratios of the limestone and terra rossa, the soils were described as representing a well washed soil completing the leaching and accumulation phase, but not totally completing the silicate weathering phase. In the processes of soil formation, 97.76% of the limestone was washed away; only 2.24% of limestone was deposited as soil. Therefore, 61 times mass reduction was realized.  相似文献   

Numerical simulations of landslide-stabilizing piles: a remediation project in Söke,Turkey     

Mehmet Rifat Kahyaoğlu  Gökhan İmançlı  Gürkan Özden  Arif Ş. Kayalar 《Environmental Earth Sciences》2017,76(19):656

A catastrophic landslide following a rainy season occurred in the backyard of a school building in Söke, Turkey. The landslide caused property damage and adversely affected the present forest cover. Immediately after the landslide, double-row stabilizing piles were designed and constructed based on the findings of two-dimensional (2D) finite element (FE) analyses to take an urgent precaution. To remedy the problem, pile displacements were monitored using inclinometers, and it was observed that the measured displacements were greater than the values calculated in the design stage. Accordingly, two different three-dimensional (3D) numerical FE models were used in tandem with the inclinometer data to determine the load transfer mechanism. In the first model, numerical analyses were made to predict the pile displacements, and while the model predicted successfully the displacement of the piles constructed in the middle with reasonable accuracy, it failed for the corner piles. In the second model, the soil load transfer between piles was determined considering the sliding mass geometry, the soil arching mechanism and the group interaction between adjacent piles. The results of the second model revealed that the middle piles with large displacements transferred their loads to the corner piles with smaller displacements. The generated soil loads, perpendicular to the sliding direction, restricted pile deformations and piles with less displacement were subjected to greater loads due to the bowl-shaped landslide. A good agreement between the computed pile displacements and inclinometer data indicates that the existing soil pressure theories should be improved considering the position of the pile in the sliding mass, the depth and deformation modulus of stationary soil, the relative movement between the soil and piles and the relative movement of adjacent piles.  相似文献   

Late Cenozoic deformation in the South Caspian region: effects of a rigid basement block within a collision zone     

Mark B. Allen  Stephen J. Vincent  G. Ian Alsop  Arif Ismail-zadeh  Rachel Flecker   《Tectonophysics》2003,366(3-4):223-239

Active deformation in the South Caspian region demonstrates the enormous variation in kinematics and structural style generated where a rigid basement block lies within a collision zone. Rigid basement to the South Caspian Basin moves with a westward component relative both to stable Eurasia and Iran, and is beginning to subduct at its northern and western margins. This motion is oblique to the approximately north–south Arabia–Eurasia convergence, and causes oblique shortening to the south and northeast of the South Caspian Basin: thrusting in the Alborz and Kopet Dagh is accompanied by range-parallel strike–slip faults, which are respectively left- and right-lateral. There are also arcuate fold and thrust belts in the region, for two principal reasons. Firstly, weaker regions deform and wrap around the rigid block. This occurs at the curved transition zone between the Alborz and Talysh ranges, where thrust traces are concave towards the foreland. Secondly, a curved fold and thrust belt can link a deformation zone created by movement of the basement block to one created by the regional convergence: west-to-east thrusts in the eastern Talysh represent underthrusting of the South Caspian basement, but pass via an arcuate fan of fold trains into SSW-directed thrusts in the eastern Greater Caucasus, which accommodates part of the Arabia–Eurasia convergence. Each part of the South Caspian region contains one or more detachment levels, which vary dependent on the pre-Pliocene geology. Buckle folds in the South Caspian Basin are detached from older rocks on thick mid-Tertiary mudrocks, whereas thrust sheets in the eastern Greater Caucasus detach on Mesozoic horizons. In the future, the South Caspian basement may be largely eliminated by subduction, leading to a situation similar to Archaean greenstone belts of interthrust mafic and sedimentary slices surrounded by the roots of mountain ranges constructed from continental crust.  相似文献   

Automatic extraction of sparse trees from high-resolution ortho-images     

Bulent Bayram  Dursun Zafer Seker  Akhtar Jamil  Hatice Catal Reis  Nusret Demir  Salih Bozkurt  Abdulkadir Ince  Turgay Kucuk 《Arabian Journal of Geosciences》2018,11(12):319

Obtaining information about tree species distribution in agricultural lands is a topic of interest for various applications, such as tree inventory, forest management, agricultural land management, crop estimation, etc. This information can be derived from images obtained from modern remote sensing technology, which is the most economical way as compare to field surveys covering large geographic areas. Therefore, in this study, a new method is proposed for extraction and counting of sparse and regular distributed individual pistachio trees from agricultural areas on large scale from high-resolution digital ortho-photo maps, which were obtained using an airborne sensor (Ultracam-X). The input images were first smoothed by applying Gaussian filter to reduce the impact of noise. Normalized difference vegetation indices (NDVI) were then derived to obtain vegetation areas followed by Otsu’s global thresholding algorithm to obtain candidate tree areas. Further, connected component (CC) analysis was applied to segregate each object. Morphological processing was performed to fill holes within tree objects and get smooth contours, which were obtained by using the Moore-neighbor tracing method (MNTM) for each CC, while geometrical constraints were applied to undermine possible non-tree elements from output image. To further improve the segmentation results for sparse trees, a new method was applied, called quadratic local analysis (QLA). QLA helped to segment the trees, which were missed by the Otsu method due to low contrast and resulted in improved accuracy (3–6%). The obtained results were compared with well-known support vector machine (SVM) classifier. Proposed method produced slightly better results (1–5%) than SVM for extraction of pistachio trees and obtained accuracy for QLA and SVM were 96 and 91% for region 1, while 91 and 90% for region 2 respectively.  相似文献   

The evolution of an electrical fittings industrial cluster in Pakistan     

Ullah  Sana  Majeed  Muhammad Tariq  Arif  Babur Wasim 《GeoJournal》2021,86(6):2657-2670

GeoJournal - This study provides an evolution process of electrical fittings industrial cluster in Pakistan by using two rounds of survey dataset (2008 and 2017) taken from the electrical fittings...  相似文献   

Spatial variability of climatic hazards in Bangladesh     

Chowdhury  Md. Arif  Zzaman  Rashed Uz  Tarin  Nusrat Jahan  Hossain  Mohammad Jobayer 《Natural Hazards》2022,110(3):2329-2351

Natural Hazards - Climate change is evident with the extreme climatic indices changing all over the world. Bangladesh is one of the most vulnerable countries to climate change. The patterns of...  相似文献   

A cost-effective device and methodology to compute aquifer transmissivity and piezometry from free-flowing artesian wells     

Toulier  Alix  Lachassagne  Patrick  Hendrayana  Heru  Fadillah  Arif  Jourde  Hervé 《Hydrogeology Journal》2022,30(6):1917-1931

Artesian aquifers offer interesting opportunities for water supply by providing a low-vulnerability groundwater resource that is easily abstracted without any installation of pumps or power supply costs. However, hydraulic tests are challenging to perform, notably where the piezometric head is above ground level with free-flowing wells not equipped with valves and open for years. This paper describes a low-cost, easy to reproduce and adaptable device, the free-flowing artesian well device (FFAWD), which is mainly designed with a set of PVC tubes equipped with a pressure probe and a valve. This device is used to perform hydraulic tests on free-flowing artesian wells, to measure the piezometric head of the aquifer and to compute its transmissivity. The practical use of the FFAWD is described and a method is proposed to compute the piezometric head and the transmissivity of the aquifer from this data set (free-flowing well discharge and pressure increase measurements) with any adapted analytical solution, using the Houpeurt-Pouchan method. Artefacts such as post-production effects, surge effects, and the impact of a leaky well are identified to avoid any misinterpretation. The FFAWD was applied to the volcano-sedimentary artesian plain of Pasuruan (Indonesia). The advantages and limitations of using the device, along with the interpretation methodology, are also discussed.

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