بررسي پارامتري رفتار سدهاي پاره سنگي با رويه بتني تحت شرايط استاتيكي و ديناميكي

چكيده انگليسي :

Behaviour Study of Concrete Faced Rockfill Dams in Static and Dynamic Condition Ebrahim Hassankhani e hasankhani@cv iut ac ir April 27 2010 Department of Civil Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi Supervisor Mahmood Vafaeian mahmood@cc iut ac ir Abstract In Concrete Faced Rockfill Dams CFRDs the role of impermeability of concrete face is a key factor on the dam design Dam body and concrete face slabs deform as a result of reservoir impoundment and the crest settlements Concrete face deformation leads to development of excess tensile and compressive stresses in the face while perimetric joint opening is also possible The dynamic behaviour of CFRDs under ground excitation has got much attention in recent decades emphasizing the needs for comperhensive studies accounting for different affecting parameters Development of high value stresses in concrete face can lead to face slab cracking and leakage of reservoir water Perimetric joint opening is also one of the most important factors in reservoir water leakage In this thesis the effect of different geometric parameters dam body material characteristics and interface behaviour between concrete face and cushion layer in the static condition and effect of reservoir water loading slab thickness earthquake acceleration dam body material characteristics and dam height in the dynamic condition on dam body deformation and specially concrete face behaviour have been studied The nonlinear behaviour of rockfill is modeled using Modified Drucker Prager Cap Plasticity constitutive model while linear elastic model is adopted to simulate the concrete face behaviour Mohr Columb constutive model has been used to simulate interface behaviour whereas the concrete face is capable of sliding along and sepration from dam body upstream face 2D finite element static and dynamic analyses have been performed employing ABAQUS V 6 7 software Analyses results indicated that the most part of deformations in dam body and concrete face occur as a result of reservoir impoundment Having reservoir filled up the face slab out of plane deformations increas and the tensile and compressive stresses start to be develop at the toe and midlength of the face slab respectively The most important factors in CFRD performance could be referred to dam height and material characteristics of dam body in the main zone Having the height of dams increased or the body matterial stiffness decreased the tensile stresses of concrete face at the toe will be increased Another words the growth of face slab out of plane deformations results more tensile stresses and an increase to perimetric joint opening However it is not essentially a case in the case of compressive stresses induced in the face slab In full reservoir condition while CFRD is subjectes to earthquake loading high value of stresses develop in the concrete face For the dynamic response earthquake acceleration dambody material characteristics and dam height are of the important factors affecting on stresses in the concrete face The effect of various parameters on developed stresses somewhere 40 percent face length close to dam crest are not significant exceptional in case of dam height and face slab thickness parameter analyses It is concluded that maximume stresses in the concrete face slab are expected to occur somewhere around 10 to 40 percent of face slab length measured from slab toe The results also indicated that the crest settlements regarding to dam height is not significant in the static and dynamic conditions and maximume permanent deformations in the dam body due to earthquake loading would be visible near the dam crest on the downstream region In general earthquake occurance can lead to development of high value of tensile and compressive in slope stresses in face slab and so severe damages in this element subject to earthquake is mostly inevitable Key Words Concrete Face Deformations Stress Expansion

حسن خاني،ابراهيم

بررسي پارامتري رفتار سدهاي پاره سنگي با رويه بتني تحت شرايط استاتيكي و ديناميكي

تغيير شكل ها , تنش هاي توسعه يافته , الاستوپلاستيك , اجزاء محدود , زلزله