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چكيده انگليسي :

Numerical Modeling of Rammed Aggregate Pier s Construction Process and it s Effect on RAPs Behavior Pegah Jarast Shamsabadi Date of Submission March 4 2012 Department of Civil Engineering Isfahan University of Technology Isfahan 84156 83111 IranDegree M Sc Language FarsiSupervisor Dr Amirmahdi Halabian mahdi@cc iut ac ir Advisor Dr Hamid Hashemolhosseini hamidh@cc iut ac iUAbstract Construction over highly compressible soils can create excessive settlement and bearing capacity problems To overcome these difficulties deep foundation elements such as driven piles or drilled shafts have beentraditionally used to transfer the surcharge loads exerted by the superstructures to a more competent layer at greaterdepths Although deep foundation methods have proven to be effective in most cases these methods are relativelyexpensive when constructed over large areas and may also cause unwanted delay during construction As alternatives to deep foundation methods ground improvement technologies have been widely used to improvethe load carrying capacity and stiffness of shallow soil layers located immediately underneath the superstructures Over the past 70 years soil improvement technologies have mainly focused on the development of vibratorymethods for densification of cohesionless soils injection and grouting materials and procedures and new conceptsof soil reinforcement Among other soil reinforcement technologies rammed aggregate pier systems have beenemerging rapidly during the last two decades to become one of the most popular methods for stiffing and stabilizingsoft soils in the United States Rammed Aggregate Piers also known as Geopier Soil Reinforcement technologywas developed in the early 1980s to provide an economical alternative to deep foundations and traditional methodsof soil improvement such as overexcavitation and replacement Since the inception rammed aggregate piers havebeen used to support a wide range of structures including column footings highway embankments heavily loadedslabes slopes retaining walls and industrial storage tanks Typical application of rammed aggregate pier systemsinclude settlement control bearing capacity improvement slope stabilization uplift capacity enhancement andliquefaction mitigation Since rammed aggregate piers are relatively short and generally not intended to penetrate toa competent layer the rammed aggregate piers system is essentially a floating system Although this technique havebeen developed in many projects studies due to understanding the behavior of rammed aggregate piers are not somuch and have been focoused on full scale load tests on isolated piers or pier groups So use of nummericalmodeling of piers and parametric study in this aspect is necessary Nummerical analyses which have been done inthis aspect in most cases don t consider installation effects or considering it with not so much accuracy while withlooking at studeies which have been done it can be seen that exact modeling of installing process is so importantand don t considering it may cause mistake in results In other hand recent progresses in aspects of analyses ofproblems with new nummerical methods which improve accuracy of analyses and make them reliable have openeda new window for investigation geotechnical cases The goal of this research is to modeling the construction oframmed aggregate piers using both distict element method and finite element method A parametric study alsoperformed in different conditions of geometry and matrix soil properties These studies not only help to betterundrestanding the pier behavior but also it can be used as a tool for predecting the expansion of pier in differentconditions Key words Nummerical methods distict element RAPs construction process

جرست شمس آبادي، پگاه

مدلسازي فرآيند ساخت پايه هاي سنگريزه اي كوبيده شده و بررسي تاثير آن بر رفتار پايه ها

تحليل عددي , المان مجزا