Laboratory study of soil-CFRP interaction using pull-out test     

Vahid Toufigh  Farnam Saeid  Ahad Ouria  Chandrakant S. Desai  Hamid Saadatmanesh 《Geomechanics and Geoengineering》2014,9(3):208-214

Soil is a material which is weak in tension; however, different materials such as geotextiles are used to address this inadequacy. In recent years more than one million square metres of geotextiles were used for reinforcing soil. Nevertheless, there are several significant problems associated with geotextiles, such as creep, low modulus of elasticity and susceptibility to aggressive environments. Carbon fibre reinforced polymer (CFRP) was introduced over two decades ago to the field of structural engineering and it can also be used in geotechnical engineering. CFRP has all the benefits associated with geotextiles and it boasts a higher strength, higher modulus, no creep and reliability in aggressive environments. In this investigation, the interface properties of CFRP-sand and fine sand were investigated using the pull-out test. The pull-out test device was designed and assembled using a triaxial loading device and a direct shear device. In the pull-out test, the normal force applied by the triaxial loading and pull-out force is applied by a direct shear device. CFRP samples were prepared in the lab. Precast and cast-in-place samples were tested. The pull-out force and corresponding displacements of each of the materials were recorded and compared.  相似文献   

Distribution of heavy metals in the clastic fine-grained sediments of Gavkhuni playa lake (Southeast of Isfahan,Iran)   总被引：1，自引：1，他引：0  

Hamid Reza Pakzad  Mehrdad Pasandi  Hajar Rahimi 《Environmental Earth Sciences》2014,71(11):4683-4692

The sedimentary basin of Gavkhuni playa lake includes two sedimentary environments of delta and playa lake. These environments consist of mud, sand and salt flats. There are potentials for concentration of heavy metals in the fine-grained sediments (silt and clay) of the playa due to existence of Pb/Zn ore deposits, industrial and agricultural regions in the water catchment of Zayandehrud River terminating to this area. In order to study the concentration of heavy metals and the controlling factors on their distribution in the fine-grained sediments, 13 samples were taken from the muddy facies and concentration of the heavy metals were determined. The results showed that the heavy metal concentrations range in the sediments (in ppm) are Mn (395.5–1,040), Sr (100.4–725.76), Pb (14.66–91.06), Zn (23.59–80.9), Ni (37–73.66), Cu (13.83–29.83), Co (5.73–13.78), Ag (3.03–4.76) and Cd (2.3–5.5) in their order of abundances. The concentration of Ag is noticeable in the sediments relative to the average concentration of this element in mud sediments. The amounts of Pb and Zn are relatively high in all the samples in comparison with the other elements. The concentration of Ni is relatively high in the oxidized samples. The distribution of Pb is directly related to organic matter content of the sediments. The concentrations of Zn, Sr, Cu, Co and Cd in the samples of the playa are lower than those in the delta. The amount of illite is another factor influencing Zn and Pb concentrations. Sr is more concentrated in the sediments with the high content of calcium carbonate. The distribution pattern of Cu, Co, Pb and Mn resembles to that of the clay content of the sediments. The clay content shows positive correlations with Co, Cu and Mn concentrations and negative correlation with Ag. The Sr and Ag concentrations are positively correlated with the amount of CaCO₃. The amounts of Co, Cu, Ni and Mn show negative correlations with the calcium carbonate content. Pb and Co are noticeably correlated with Mn.  相似文献   

Optimal water and waste load allocation in reservoir–river systems: a case study     

Mohammad Reza Nikoo  Reza Kerachian  Akbar Karimi  Ali Asghar Azadnia  Keighobad Jafarzadegan 《Environmental Earth Sciences》2014,71(9):4127-4142

In this paper, a new methodology is developed for optimization of water and waste load allocation in reservoir–river systems considering the existing uncertainties in reservoir inflow, waste loads and water demands. A stochastic dynamic programming (SDP) model is used to optimize reservoir operation considering the inflow uncertainty, and another model called PSO-SA is developed and linked with the SDP model for optimizing water and waste load allocation in downstream river. In the PSO-SA model, a particle swarm optimization technique with a dynamic penalty function for handling the constraints is used to optimize water and waste load allocation policies. Also, a simulated annealing technique is utilized for determining the upper and lower bounds of constraints and objective function considering the existing uncertainties. As the proposed water and waste load allocation model has a considerable run-time, some powerful soft computing techniques, namely, Regression tree Induction (named M5P), fuzzy K-nearest neighbor, Bayesian network, support vector regression and an adaptive neuro-fuzzy inference system, are trained and validated using the results of the proposed methodology to develop real-time water and waste load allocation rules. To examine the efficiency and applicability of the methodology, it is applied to the Dez reservoir–river system in the south-western part of Iran.  相似文献   

Removal of uranium(VI) from aqueous solutions using Eucalyptus citriodora distillation sludge     

H. N. Bhatti  S. Hamid 《International Journal of Environmental Science and Technology》2014,11(3):813-822

Adsorption and desorption of uranium(VI) from dilute aqueous solutions by Eucalyptus citriodora distillation sludge was studied in a batch mode. The potential of Eucalyptus citriodora distillation sludge to remove uranium(VI) from aqueous solutions has been investigated at different conditions of solution pH, metal ion concentrations, biosorbent dosage, biosorbent particle size, contact time and temperature. The results indicated that biosorption capacity of Eucalyptus citriodora distillation sludge was strongly affected by the medium pH, the biosorbent dose, metal ion concentrations and medium temperature. Reduction in particle size increased the biosorption capacity. Langmuir and Freundlich isotherm models were applied to biosorption data to determine the biosorption characteristics. An optimum biosorption capacity (57.75 mg/g) was achieved with pH 4.0, particle size 0.255 mm, biosorbent dose 0.5 g/100 mL and initial uranium(VI) concentration of 100 mg/L. Uranium(VI) removal by Eucalyptus citriodora distillation sludge was rapid, the equilibrium was established within 60 min and pseudo-second-order model was found to fit with the experimental data. The biosorption process decreased with an increase in the temperature indicating its exothermic nature. Pretreatments of biomass with different reagents affected its biosorption capacity. A significant increase (34 %) in biosorption capacity (83.25 mg/g) was observed with benzene treatment. Fourier-transform infra-red studies showed the involvement of carbonyl, carboxyl and amide groups in the biosorption process. The results indicated that sulfuric acid had the best effects as an eluent showing 93.24 % desorption capacity.  相似文献   

Application of artificial intelligence techniques for predicting the flyrock distance caused by blasting operation   总被引：2，自引：0，他引：2  

Ebrahim Ghasemi  Hasel Amini  Mohammad Ataei  Reza Khalokakaei 《Arabian Journal of Geosciences》2014,7(1):193-202

Flyrock arising from blasting operations is one of the crucial and complex problems in mining industry and its prediction plays an important role in the minimization of related hazards. In past years, various empirical methods were developed for the prediction of flyrock distance using statistical analysis techniques, which have very low predictive capacity. Artificial intelligence (AI) techniques are now being used as alternate statistical techniques. In this paper, two predictive models were developed by using AI techniques to predict flyrock distance in Sungun copper mine of Iran. One of the models employed artificial neural network (ANN), and another, fuzzy logic. The results showed that both models were useful and efficient whereas the fuzzy model exhibited high performance than ANN model for predicting flyrock distance. The performance of the models showed that the AI is a good tool for minimizing the uncertainties in the blasting operations.  相似文献   

GIS-based landslide susceptibility mapping with probabilistic likelihood ratio and spatial multi-criteria evaluation models (North of Tehran,Iran)   总被引：7，自引：0，他引：7  

H. R. Pourghasemi  H. R. Moradi  S. M. Fatemi Aghda  C. Gokceoglu  B. Pradhan 《Arabian Journal of Geosciences》2014,7(5):1857-1878

The aim of this study is to produce landslide susceptibility mapping by probabilistic likelihood ratio (PLR) and spatial multi-criteria evaluation (SMCE) models based on geographic information system (GIS) in the north of Tehran metropolitan, Iran. The landslide locations in the study area were identified by interpretation of aerial photographs, satellite images, and field surveys. In order to generate the necessary factors for the SMCE approach, remote sensing and GIS integrated techniques were applied in the study area. Conditioning factors such as slope degree, slope aspect, altitude, plan curvature, profile curvature, surface area ratio, topographic position index, topographic wetness index, stream power index, slope length, lithology, land use, normalized difference vegetation index, distance from faults, distance from rivers, distance from roads, and drainage density are used for landslide susceptibility mapping. Of 528 landslide locations, 70 % were used in landslide susceptibility mapping, and the remaining 30 % were used for validation of the maps. Using the above conditioning factors, landslide susceptibility was calculated using SMCE and PLR models, and the results were plotted in ILWIS-GIS. Finally, the two landslide susceptibility maps were validated using receiver operating characteristic curves and seed cell area index methods. The validation results showed that area under the curve for SMCE and PLR models is 76.16 and 80.98 %, respectively. The results obtained in this study also showed that the probabilistic likelihood ratio model performed slightly better than the spatial multi-criteria evaluation. These landslide susceptibility maps can be used for preliminary land use planning and hazard mitigation purpose.  相似文献   

Validating gap-filling of Landsat ETM+ satellite images in the Golestan Province,Iran   总被引：2，自引：0，他引：2  

M. Mohammdy  H. R. Moradi  H. Zeinivand  A. J. A. M. Temme  H. R. Pourghasemi  H. Alizadeh 《Arabian Journal of Geosciences》2014,7(9):3633-3638

The Landsat series of satellites provides a valuable data source for land surface mapping and monitoring. Unfortunately, the scan line corrector (SLC) of the Landsat7 Enhanced Thematic Mapper plus (ETM+) sensor failed on May 13, 2003. This problem resulted in about 22 % of the pixels per scene not being scanned and has seriously limited the scientific applications of ETM+ data. A number of methods have been developed to fill the gaps in the incorrect images. Most of these methods have problems in heterogeneous landscapes. We applied and validated a simple and effective gap-fill algorithm developed by the US Geological Survey to a study area in the Golestan Province in the north of Iran. This algorithm operates under the assumption that the same-class neighboring pixels around the unscanned pixels have similar spectral characteristics, and that these neighboring and unscanned pixels share patterns of spectral differences between dates. For validation, unsupervised land use classification was performed on both gap-filled SLC-off data and the original “sound” data set. Classification results and accuracies were very comparable.  相似文献   

Investigation of surface and subsurface displacements due to multiple tunnels excavation in urban area     

Alireza Talebinejad  Hamid Chakeri  Mahdi Moosavi  Yılmaz Özçelik  Bahtiyar Ünver  Mehmet Ali Hindistan 《Arabian Journal of Geosciences》2014,7(9):3913-3923

Underground structures are currently widely used and are built as urbanism develops. The interactions between perpendicularly crossing and parallel tunnels in the Tehran region are investigated by using a full three-dimensional (3D) finite difference analysis with elastic-plastic material models. Special attention is paid to the effect of subsequent tunneling on the support system, i.e., the shotcrete lining and rock bolts of the existing tunnel. Eventually, as the tunnels are excavated at certain levels, the interaction between the tunnels will certainly have a significant influence on both stress distribution and consequently deformations. Since multilayer tunneling is a three-dimensional phenomenon in nature, 3D numerical solutions must be utilized for analyzing effect of perpendicularly crossing tunnels at various levels. As Tohid twin tunnels and Line 7 pass beneath the Line 4 metro tunnel, changes in stress distribution, deformations, and surface settlements are studied for various conditions and the results are presented in this paper. Consequently, it is shown that there is a significant interaction between tunnels that necessitate certain preventive measures to maintain a stable tunneling operation.  相似文献   

Readout Techniques for Drift and Low Frequency Noise Rejection in Infrared Arrays     

Gert Finger  Reinhold J. Dorn  Alan W. Hoffman  Hamid Mehrgan  Manfred Meyer  Alan F. M. Moorwood  Joerg Stegmeier 《Experimental Astronomy》2002,14(2):117-127

Three different methods are presented to subtract thermal drifts and low-frequency noise from the signal of infrared array. The first is dead pixels with open Indium bumps, the second is reference output as implemented on the Hawaii2 multiplexer, and the third is dark pixels to emulate reference cells having a capacity connected to the gate of the unit cell field-effect transistor (FET). The third method is the most effective and yields a reduction in readout noise from15.4–9.4 erms. A novel method will be described to extend this readout technique to the Aladdin 1 K × 1 K InSb array. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Three-dimensional discontinuous deformation analysis (3-D DDA) using a new contact resolution algorithm     

S. Amir Reza Beyabanaki  Roozbeh Geraili Mikola  Kianoosh Hatami   《Computers and Geotechnics》2008,35(3):346-356

This paper presents a new contact calculating algorithm for contacts between two polyhedra with planar boundaries in the three-dimensional discontinuous deformation analysis (3-D DDA). In this algorithm, all six type contacts in 3-D (vertex-to-face, vertex-to-edge, vertex-to-vertex, face-to-face, edge-to-edge, and edge-to-face) are simply transformed into the form of point-to-face contacts. The presented algorithm is a simple and efficient method and it can be easily coded into a computer program. In this paper, formulations of normal contact, shear contact and frictional force submatrices based on the new method are derived and the algorithm has been programmed in VC⁺⁺. Examples are provided to demonstrate the new contact rule between two blocks.  相似文献