TA747 : Investigating the behavior of Helical piles under monotonic loading at different speeds and cyclic loading at different amplitudes and frequencies
Thesis > Central Library of Shahrood University > Civil & Architectural Engineering > MSc > 2023
Authors:
Abstarct:
Today, one of the primary challenges geotechnical engineers face in dealing with problematic soils is choosing a suitable improvement method that, in addition to strengthening the soil, does not cause harmful damage to the environment. The use of Helical piles is a new method that has become very popular in recent years due to the unique features of this type of pile, the most important of which is that it is environmentally friendly. Due to their unique shape and section (having one or more helixes along the shaft of the pile), Helical piles have a higher load capacity than usual concrete piles.
According to past studies, it has been found that the current knowledge of the performance of this type of pile and the methods of predicting and determining the bearing capacity currently needs to be improved, which shows the necessity of researching the behavior of these piles. This study investigates the behavior of single-helix and double-helix Helical piles under monotonic loading at different speeds at two densities in the first stage. Also, in the second stage, the behavior of this model of piles under cyclic loading at different amplitudes and frequencies was studied. All the experiments in this study were done using the 1g physical modeling device.
The results obtained in this study show that in monotonic tests, the ultimate bearing capacity decreased by about 56% with increasing loading speed. On the other hand, with increasing relative density and the number of helix (from one to two), the ultimate bearing capacity has increased by about 468% and 54%, respectively. Also, in cyclic tests, the number of cycles that bring the pile to the breaking range has decreased by increasing the Frequency and amplitude of oscillation. However, the presence of the second helix does not affect the number of cycles. By comparing the post-cyclic bearing and monotonic bearing capacity, it has been determined that they were similar to each other with increasing Frequency in the single-helix pile. In contrast, in the double-helix pile, the post-cyclic bearing capacity was half of the monotonic bearing capacity, which indicates that the presence of the second helix in the cyclic tests Not only does not improve the bearing capacity but also causes a decrease in the bearing capacity and leads to earlier rupture of the pile, which is due to the two-helix pile causing more disturbance with the soil and placing the second helix in the affected area.
Keywords:
#Helical pile #Physical modeling #Monotonic and Cyclic test #Loading speed #Frequency Keeping place: Central Library of Shahrood University
Visitor:
Visitor: