عنوان مقاله [English]
Advantages of technological and economic of rammed aggregate piers system (RAPs) in stabilization of the soft soils are due to develop their applications in civil engineering. Over the last two decades, being of these benefits is the main motivation to develop research in this field. In this study, the effect of RAP diameter has been studied on the bearing capacity, settlement, the stiffness modulus, and the load ratio of RAP. In total, eight in situ loading tests has been done on two groups of single RAPs. The nominal length of RAPs was 1 m and their nominal diameters varied from 105 to 185 mm. The testing area consisted of relatively uniform saturated soft alluvial clay overlain by a 1-m-thick wet soft-to-stiff silt layer.
In order to load the rammed aggregate piers, mobile reaction beams, in the form of a loading cart and a modular rail system, were used, both to speed up the tests and to make them more economical. The results show, the rate of increase of the load ratio (tip to top) in RAPs with bigger diameters is considerably higher than the rate of increase of the load ratio (tip to top) in the RAPs with smaller diameter. In addition, by increasing the applied stress at the top of the RAP, the difference is also raised. In fact, the RAPs with smaller diameter are more likely to experience bulging deformation, and the RAPs with bigger diameter are more likely to experience tip deformation. So, in a two-layer soil system which the strong layer is on the weak layer, the use of RAPs with smaller diameter will desirable. Interpretations of the test results are particularly focused on the load-settlement behaviors of the single RAPs, stiffness modulus and the load ratio in terms of stress at the top of the RAPs.