Numerical Analysis of Bearing Capacity of Helical Piles under Inclined Tensile Loading in Sandy Soil

نوع: Type: thesis

مقطع: Segment: masters

عنوان: Title: Numerical Analysis of Bearing Capacity of Helical Piles under Inclined Tensile Loading in Sandy Soil

ارائه دهنده: Provider: vahide suri

اساتید راهنما: Supervisors: Masoud Makarchian, Ph. D

اساتید مشاور: Advisory Professors:

اساتید ممتحن یا داور: Examining professors or referees: Mohamad Maleki, Ph. D. and Meysam Zarinfar, Ph. D

زمان و تاریخ ارائه: Time and date of presentation: 2022/09/12

مکان ارائه: Place of presentation: Department: Civil Engineering

چکیده: Abstract: Piles or deep foundations are relatively thin columns that are used vertically or slightly inclined as the foundations of structures, so as to transfer the load of upper structures to more suitable layers of soil at lower depths. The helical pile is one of the types of piles, which has many advantages, and its use has expanded in recent decades in engineers' projects to strengthen structures and support under tensile, compressive, and lateral loads. The helical pile (as a new method for deep foundations) has found many uses due to its advantages over the normal pile, and its use is expanding. Among its applications, it is used in the mast foundation of high-pressure transmission lines, stabilization of slopes, control of pits, foundations of piers and bridges, oil and gas projects, and power transmission lines. In this research, using Plaxis 3D software version 2020, the behavior of helical piles under inclined tensile load in sandy soil is modeled and the effect of various parameters, including changing the distance between blades, changing the characteristics of soil layers, changing the diameter of helical plates and applying tensile load at different angles. will be examined. Helical pile with length (L) 4 meters and central rod diameter (d) 15 cm with blade diameter (D) 28, 34 and 40 cm with the distance between the blades 1, 1. 5, 2, 2. 5 and 3 times the diameter of the blade. With the number of 1, 2 and 3 blades, it is placed under the tension angles (α) of 0, 30, 60 and 90 degrees relative to the pile axis in sandy soil with a relative density of 50, 64 and 75%. According to the results of the tests, the bearing capacity of the helical pile increased compared to the pile without blades in the upward thrust state, while it did not change much in the lateral state because the participation of the helical blade decreased. Increasing the distance between the vanes increases the lift capacity, but in the inclined loading, there was a partial increase and sometimes a decrease in the load capacity, and with the increase in the relative density of the soil, the values of the decrease or increase in the load capacity also increased. The relative density increased with a significant slope and increased with a gentle slope in the inclination angle. With the increase in the diameter of the blades, there was an increase in the lifting capacity Determining the bearing capacity was based on the method of ten percent of the mean blade diameter, the least bearing capacity was at 30 degrees angle and the highest bearing capacity was at 0 degree angle. In changing the angle from 30 degrees to 60 degrees, it increased between 15 and 88 percent and from 60 to 90 degrees between 29 and 48 percent. The percentage of increase in the bearing capacity of two-bladed helical piles compared to single-bladed piles was more than that of three-bladed piles compared to two-bladed piles

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