JOURNAL OF FACULTY OF ENGINEERING (UNIVERSITY OF TABRIZ)
Year:2007 | Volume:33 | Issue:3 (45) CIVIL ENGINEERING|Papers Count:9

The sorption characteristics of soils, which are fundamental to contaminant attenuation, depend on many soil-related and contaminant-related factors. The carbonate-rich soils in semi-arid regions provide the motivation for this study on the role of carbonates on contaminant attenuation. Previous reported studies have shown that carbonates exert considerable influence on the retention of heavy metals in soils. This study investigates kaolinite-calcite-contaminant interaction at different pH values and heavy metals concentrations. Particular attention is paid to the resultant effect on contaminant attenuation. To achieve the stated objectives, several batch equilibrium and XRD analyses were performed. pH control experiments were conducted to evaluate the influence of calcite content on sorption of Zn in the kaolinite-calcite mixtures. The interaction process of the clay fraction and carbonate was monitored through XRD analyses of the soil samples at various stages of the tests. It is concluded that the presence of carbonate minerals in clayey soils causes an increase in heavy metal attenuation of kaolinite.

GPS system, a satellite positioning system with an accuracy about centimeter under special methods and conditions is used by smoothing algorithm for determining non real time location in Kinematic case. This algorithm works based on previous epoches phase observation and after the desired epoch. Since in this method more observations are used relative to real time location determining with Kalman filtering algorithm, it is expected to have good accuracy. To study this matter, both methods were tested with phase observations in Kinematic case. Comparing the variance covariance matrix of obtained unknowns showed the accuracy of the smoothing algorithm. The obtained results and the comparison are given by all epoch standard deviation graphs in this paper.

Description of time dependent deformation of soils in terms of visco-elastic models is a useful method that can be employed to improve many deficits of current conventional methods of evaluation of soil consolidation behavior. In this research creep behavior of different soil specimens are evaluated and it is shown that the secondary consolidation behavior may be well defined with the generalized Maxwell visco-elastic model. Several consolidation tests on different remolded and undisturbed soil specimens were carried out and time dependent behavior was studied. The dependency of constants of the generalized Maxwell model on the effective stress level and also dependency of creep settlement pattern on the variations of constants of the proposed model were appraised. It was concluded that the proposed model is an effective and useful tool for defining of complete settlement behavior explicitly in long term.

The construction of the causeway of Shahid Kalantari Highway has attracted various researchers due to its social and economical impact on the region. In the present paper, the limitation of capacity of Urmia Lake and vast amount of entering sediments has been considered. After estimation of the amount of entering sediments of the lake and determination of the portions of the southern and northern parts of the lake, it is found that inequality of these portions has significant effect on the design of the causeway and the stability of the highway. Also, it is recognized that in the case of complete separation of the southern and northern parts from each other, the increase in the height of sedimentation in southern part will be approximately 40mm up to 50mm more than that of the northern part in each year. Therefore, this phenomenon will result in non-symmetrical stresses between two sides of the highway which will be increased by passing time. Therefore, the stability of the causeway will be damaged.

This Paper is prepared to provide the state of the art of the seismic behavior as well as seismic design of steel shear walls. This Paper contains a summary of the behavior of steel shear walls under cyclic load as well as during post earthquakes. Later, one and four stories panel with and without stiffeners is studied. For this purpose, various models of such walls are analyzed and modeled. The Result shows that ductility of the system at Nonlinear Zone is increasing and the steel plate -against the steel frame- has nonlinear behavior. Also, lateral drift at the steel shear wall with stiffener is decreasing but lateral drift of the four stories panel at middle beams level is increasing at compared with the non stiffener wall.

Simultaneous error removal with feature digitization, in the map production process eliminates spatial data editing stage after digitization operations. In this case, spatial information can be directly entered to GIS. Because editing operations are carried out by using photogrammetric reference model, problems of unavailability of source data will be solved. CAD environments, as an external digitization facility in most of the photogrammetric systems, contain powerful functions for storage, retrieval, editing and displaying 3D data according to user needs. All of these functions are required for spatial data preparation to be entered into GIS system. In this paper, a new approach to detect and eliminate errors simultaneously with feature digitization process, in CAD environment has been presented. We have used primitives of object-oriented systems presented for feature modeling based on logical relations among features. To show applicability of presented method, an Object-Oriented CAD-Based Photogrammetric System (OCBPS) was designed, implemented, and tested for elimination of errors related to contour features. Results showed that based on constraints used by features to maintain logical consistency with real word, it is possible to automatically detect and eliminate some errors simultaneously with feature digitization process in CAD environment. Therefore, time and cost of spatial data production for GIS is greatly reduced and reliability of data is increased.

Correct selection of seismic parameters is one of the most important phases of the seismic assessment of a region. The parameters will be used in estimating return periods of earthquakes and also probabilistic seismic hazard computation. The methods such as Kijko and Sellevoll (1992) and the Gumbell cumulative function method are not very accurate for the reasons that will be discussed. Gutenberg-Richter method is valid for a complete file of data, which is reliable on condition that the applied data have proper accuracy. Also in Gutenberg-Richter method we have one approach to all data. Whereas some of instrumental seism city data are instrumental and some are historical. The new method proposed by the authors, has been titled "Combined Gutenberg-Richter" method. In this method, each information file of data is valid in its time range. As an example, 40 years earthquakes (instrumental earthquakes in magnitude range between 4 and 5 and recent 100 years earthquakes in magnituderangebetween5 and 6 and 1400 years earthquakes in magnitude range more than 6 are valid). To calculate the annual cumulative frequency, data of each range should be divided by the mentioned time range in order to change to annual cumulative frequency.

This paper describes the stabilisation of a calcareous soil with lime and sand (independently and combined) to be used as a road base or sub-base material in the study area. The material was collected from Vali-Asr suburb of Tabriz, East Azarbaijan Province, Iran. The strength is investigated by CBR and UCS test results. The soil stabilised with 6% lime can be utilised as a sub-base material as its soaked CBR value of 35% and UCS of 450 kPa complies with the evaluation criteria (CBR=32%, UCS=430 kPa) for the sub-base layer. The addition of 20%-50% sand improves the soil strength; however the evaluation criteria are not fully satisfied. The combined lime-sand as stabiliser agent has shortcomings in terms of strength. This method decreases the lime content to 4%.