Due to the increasing use of piles, it is essential to find the best type of piles in terms of geometry, which has proper performance against structural loads and has the most economical use of materials. Recent advances in pile technology and equipment have led to the implementation of large-scale piles in various shapes. In the meantime, implementing cylindrical piles has almost become a regular thing. Still, the constant cross-section of these piles and the fact that it has been challenging to implement them in larger diameters have pro‎mp‎ted researchers to do more research in the field of piles having a variable cross-section. Taper helical piles are obtained by combining two tapering and helical pile. You can use the benefits of both piles simultaneously, and they will perform well. The tapered helical pile consists of an axial pipe whose cross-section gradually decreases from the surface to the depth, and one or more helix plates are attached. The helical pile's shaft tapering increases the bearing capacity and stiffness. The method of installing this pile, which is applying compressive force and torque simultaneously, reduces the soil's resistance parameters around the pile. Considering the effect of plugging on the bearing capacity of cylindrical piles, this research investigates the effect of plugging on the bearing capacity of tapered helical piles under static load. To achieve this goal, physical modeling concepts have been used. For this purpose, a Fructrum Confining Vessel (FCV) was used. The parameters studied in the behavior of tapered helical piles, including the diameter of the pile helix, the distance from the first helix to the end of the pile, the tapered angle, and also the tip of the pile, were investigated and analyzed using the concepts of the Taguchi test design method. The results show that the difference between the bearing capacity of open-ended and closed-ended helical piles is equal to the inner skin frictional resistance of the pile and plugging, and the net effect of plugging for the tapered helical piles under investigation is about 16%. The type of pile tip had the greatest effect on the bearing capacity of the pile, which is simple open, diagonal open and conical closed tip respectively. Also, by reducing the diameter of the helix, the amount of soil that went into the pile increases.

اميرمهدي حلبيان , حميد هاشم الحسيني

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محمود قضاوي , محمدعلي روشن ضمير