عنوان مقاله :
ارزيابي تاثير چرخش تنش هاي اصلي اوليه در رفتار ناهمسان ماسه در شرايط زهكشي شده
عنوان به زبان ديگر :
EFFECT OF INITIAL PRINCIPAL STRESS ROTATION ON THE ANISOTROPIC BEHAVIOR OF SAND IN THE DRAINED CONDITION
پديد آورندگان :
صفاريان, محمدجواد مركز آموزش عالي فني مهندسي بوئين زهرا - گروه مهندسي عمران , محمدزاده رومياني, هادي مركز آموزش عالي فني مهندسي بوئين زهرا - گروه مهندسي عمران , رازقي, حميدرضا دانشگاه علم و صنعت ايران - دانشكده ي مهندسي عمران
كليدواژه :
شرايط تنش هاي اوليه , رفتار ناهمسان ماسه , چرخش تنش هاي اصلي , دستگاه پيچش استوانه ي توخالي , ماسه ي فيروزكوه
چكيده فارسي :
در پژوهش حاضر، تاثير چرخش تنش هاي اصلي اوليه در رفتار ناهمسان ماسه ي فيروزكوه نيمه متراكم با استفاده از دستگاه پيچش استوانه ي توخالي بررسي شده است. نمونه هاي ماسه ي فيروزكوه با روش بارش خشك ساخته شده و در مرحله ي تحكيم تحت تنش هاي ناهمسان با نسبت تنش هاي اصلي $(R_{c}=frac{sigma'_{1c}}{sigma'_{3c}}=2)$ و زواياي تنش هاي اصلي مختلف قرار گرفته اند. در مرحله ي بارگذاري، تنش انحرافي در شرايط زهكشي شده با كنترل زاويه ي اضافه ي تنش هاي اصلي تا گسيختگي نمونه افزايش يافته است. نتايج به دست آمده نشان مي دهد كه رفتار تنش كرنش و مقاومت برشي نمونه هاي ماسه يي نيمه متراكم در شرايط زهكشي شده تحت تاثير زاويه ي تنش هاي ناهمسان اوليه است. نمونه هاي تحكيم يافته تحت تنش هاي ناهمسان اوليه، مقاومت برشي و سختي كمتري نسبت به نمونه هاي تحت تنش هاي اوليه ي همسان نشان مي دهند. هم راستايي اضافه تنش هاي وارده با تنش هاي ناهمسان اوليه باعث كاهش نسبي مقاومت برشي و سختي برشي ماسه مي شود و ضريب ناهمساني به ميزان قابل توجهي افزايش مي يابد.
چكيده لاتين :
In this study, the effect of initial principal stress rotation on anisotropic behavior of medium dense Firoozkuh sand in the drained condition was studied. Hollow Cylindrical Apparatus (HCA) was used to conduct the tests in the drained
condition on the medium dense specimens of Firoozkuh sand. All specimens were
prepared with a height of 200 mm and outer and inner diameters of 100 and 60
mm, respectively, using dry air pluviation method. The specimens were
consolidated subjected to the anisotropic initial stresses with different directions (alphac).During consolidation, stress ratio (Rc=sigma′1c/sigma′3c=2)
was maintained equal to 2. Specimens were consolidated under an anisotropic
condition in which the rotation of initial principal stresses was set to a constant value varying from zero to 450. The specimens were sheared under different inclinations of principal stress increments (alphadeltasigma) varying from zero to 450. In these tests, the direction of principal stress increments
(alphadeltasigma) may be not equal to the direction of the principal stress due to anisotropic stresses, applied in the consolidation phase. Generally, the results showed a decrease in the shear strength of sand by increasing (alphadeltasigma). The results showed that the stress-strain behavior and shear strength of medium dense sand were influenced by the inclination of initial principal stresses. Initial anisotropic principal stresses caused initial shear strains which softened the stress-strain behavior of sand. Therefore, the shear modulus and shear strength for anisotropic consolidated specimens were less than that of the isotropic consolidated specimens. The anisotropic response of medium dense
sands was observed to be governed by (alphac). It was found that the shear modulus and shear strength of sand relatively decreased and anisotropy coefficient significantly increased when anisotropic initial stress and increments of principal stresses were in the same direction. The effect of initial stress state on the shear modulus was more noticeable than that on the shear strength of sand.
عنوان نشريه :
مهندسي عمران شريف
