توجه: محتویات این صفحه به صورت خودکار پردازش شده و مقاله‌های نویسندگانی با تشابه اسمی، همگی در بخش یکسان نمایش داده می‌شوند.
۱Effects of Mixing Proportions and Sample Age on Mechanical Properties of Plastic Concrete; An Experimental Study
نویسنده(ها): ،
اطلاعات انتشار: نخستین کنفرانس بین المللی تکنولوژی بتن، سال
تعداد صفحات: ۱۰
Plastic concrete, essentially composed of aggregates, cement, water and bentonite is used for creating an impermeable barrier (cut–off wall or cut–off trench) under the dams constructed on the high permeable foundation. Because of the triaxial condition of the stress on cut–off wall (vertical load from the dam body weight and confining pressure from the surrounding soil) its behavior in triaxial stress condition is very important. The available data on the triaxial behavior of plastic concrete is rare. Therefore the investigations mechanical behavior in this condition will be interesting and with the practical uses. For this purpose simple compression tests as well as triaxial compression tests were done on the samples of 10 centimeters diameter and 20 centimeters of heights with the confining pressures of 0, 300 and 500 kPa. The effect of mixing proportions and sample ages on mechanical characteristics are investigated. From the obtained results it can be concluded that an increase in cement content can increase the shear strength as well as the elastic modulus. Accepting a frictional criterion for the shear strength of plastic concrete an increase in cement content increases the cohesion coefficient but reduces the internal friction angle. Increasing the bentonite content reduces the shear strength as well as the shear parameters (C and f) and deformability and reducing the elastic modulus. The effect of confining pressure is also investigated. It is founded that the increasing in confining pressure increases the compressive strength as well as the deformability. Increasing the age of the sample, also increase the shear strength as well the elastic modulus and the cohesion coefficient but it reduces the internal friction angle. Finally, from the obtained results an empirical relation between the axial stress, confining pressure and the compressive strength is proposed.<\div>

۲Pile Foundation Behavior Analysis Considering Effects of the Ground Motion Intensity on the Soil–Pile Kinematic and Inertial Interaction Phenomena
نویسنده(ها): ، ،
اطلاعات انتشار: چهارمین همایش بین المللی مهندسی ژئوتکنیک و مکانیک خاک ایران، سال
تعداد صفحات: ۹
The study of soil–pile interaction is conducted by either direct or sub–structuring methods. In the sub–structuring approach, the kinematic and inertial interactions of the soil–structure system are studied by means of the transfer and impedance functions, respectively. In this study, pile groups of 2x2, 2x3 and 3x3 arrangements were considered and simulated by ABAQUS. Analyses were carried out in the time domain and the results were converted to their corresponding magnitudes in the frequency domain. It was found that the ground motion intensity did not influence the transfer function magnitudes. On the other hand, its effect on the inertial interaction was to reduce stiffness and increase damping in such systems.<\div>

۳3D Numerical Simulation of Support Structures in an Urban Deep Excavation – Case Study of W7 Station of Tehran Subway
اطلاعات انتشار: نهمین کنگره بین المللی مهندسی عمران، سال
تعداد صفحات: ۸
This paper concerns deep excavation modeling and analysis in an urban area (W7 station of Tehran subway) and simulation of excavation stages and construction of supporting system. Static analyses resulted in prediction of maximum ground and retaining structure movements, a movement pattern for each case and needed moment values for design purposes. Struts and tiebacks are installed in the model and have effect on different values of analyses. A 3D– Finite difference model using the Mohr–Coulomb constitutive model for soil was used to model the wall and ground movements associated with deep excavation. The groundwater is assumed as pore pressures in elevations recognized by geotechnical investigations<\div>

۴Behavior Analysis of Pile Supported Embankments
نویسنده(ها): ،
اطلاعات انتشار: نهمین کنگره بین المللی مهندسی عمران، سال
تعداد صفحات: ۷
Construction of embankments on soft or liquefiable ground is a common problem in road construction.An option gaining in popularity is to build the embankment on a grid of piles or columns that areconstructed by ground improvement techniques like deep mixing and jet grouting overlaid by a bridging layer of granular soil and one or more layers of geosynthetic reinforcements. In this way the excessive settlements is prevented. In this study a tridimensional model of ground–pile–geosynthetic layers areconsidered. Model is developed using ABAQUS code. The Interfaces between the different elements of the system such as rigid piles, surrounding ground and geosynthetic layers are considered in model. The results show an arching effect which could be due to the large stiffness of the piles in comparison to thesurrounding media. The settlement and the effectiveness of embankment on floating piles are studied. It could be concluded that generally an embankment on floating piles is an effective method for soft soil improvement<\div>
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