Numerical Study of Interference Effects for Closely Spaced Semi-Deep Foundations

نوع: Type: thesis

مقطع: Segment: masters

عنوان: Title: Numerical Study of Interference Effects for Closely Spaced Semi-Deep Foundations

ارائه دهنده: Provider: Pouyan Kochaki

اساتید راهنما: Supervisors: Dr. Mohammad Maleki

اساتید مشاور: Advisory Professors:

اساتید ممتحن یا داور: Examining professors or referees: Dr.Vahidreza Ouhadi, Dr.Meysam Zarrinfar

زمان و تاریخ ارائه: Time and date of presentation: 08.10.2022

مکان ارائه: Place of presentation: Engineering Faculty

چکیده: Abstract: Semi-deep foundation includes the range between the shallow foundation and deep foundation. The bearing capacity and settlement of shallow and deep foundations have been used from different perspectives. Although studies have been completed and developed regarding the interference effects of surface foundations close to each other for the past few decades, semi-deep foundations have been studied less regarding bearing capacity and load-settlement behavior than shallow and deep foundations. Based on the review studies, the necessity of conducting such research is felt more significantly in the case of interference effects as a function of the distance between them. In closely spaced foundations, load-settlement behaviors are influenced by each other. In other .words, the development of slip lines in the calculation of bearing capacity becomes an interference mode, and applying conventional relations in calculations faces a challenge In addition to the studies done in this research, the interference effects of semi-deep circular foundations close to each other under effective parameters in granular soil have been investigated simultaneously using finite element analysis and finite element limit analysis. The analysis results in the interference effects of semi-deep circular foundations and at the limit load indicate the increase in the bearing capacity of the foundations under interference compared to the individual foundations built under the exact foundation specifications. Due to the phenomenon of arching in the soil between the foundations under interference as a function of the internal friction angle, the bearing capacity increased from the ratio of the distance where the foundations are in direct contact with each other to the ratio of the critical distance caused by the construction between the adjacent foundations, and then continuously and It decreases as a function of the internal friction angle of the bed soil. This reduction usually occurs at a distance ratio of 5 to 6 times the width of the existing foundation. Thus, the effect of the interference of the foundations is eliminated, and the behavior of the foundations under loading will be individual. At the same time, as the depth of semi-deep foundations increases as a function of the internal friction angle and due to the less accumulated slip surfaces in the area under the interference of foundations close to each other, the interference effect is less intense compared to surface foundations. Of course, to develop slip .lines in the areas adjacent to the foundation at a lower depth ratio than the surface layer of the earth, it is recommended to build the foundation at a lower depth than the earth's surface In the present study, the equation resulting from the interference effects of foundations close to each other in a three-dimensional coordinate system was presented to investigate the effect of interference in increasing the bearing capacity of semi-deep foundations. It was concluded that unlike other research conducted in this field, which was the result of solving in a two-dimensional coordinate system, the equation in The arcing area between adjacent foundations is not the equation of a line; Rather, as a function of the ratio of the distance between the adjacent foundations and the internal friction angle of the soil, the resulting equation is a quadratic parabolic equation, which itself indicates a more substantial order of the arching effect in the soil area between the .foundations under the interference effect

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