الخلاصة:
Abstract
Communication Towers may be found in areas outside cities, where sloping
lands and hills, a self-supporting tower with four legs and a height of 50
meters with raft foundation is the typical tower adopted in this study. The
communication tower represents a lightweight structure compared to other
structures and at the same time exposed to eccentric load represented by the
overturning moment resulting from the wind load, this load depend on the
basic wind speed, and the prevailing speeds in Iraq (33, 38, 42, and 44) m/sec
are the speeds which adopted to obtain the values of eccentricity. The study
examines the behavior of tower foundation near sandy slope under the
influence of parameters: eccentricity ratio (e/B) at values (0.08, 0.11, 0.14,
and 0.15), relative density (loose, medium, dense), angle of slope at values
) with constant height of the slope (10) m and embedment depth
of the foundation (Df/B) at values (0 and 0.125), using Finite Element Method
in Plaxis 3D program, these parameters investigate with two constitutive
models: Hardening Soil Model (HSM) and Mohr Coulomb Model (MCM).
After finding a method of representing the projected moment on raft
foundation by Finite Element Method in Plaxis 3D program, results of angle
of rotation for all models of the study are compared with the permissible value
of (1/600), one of the most important findings of this study is that the ultimate
bearing capacity of the foundation was not reached, and the failure mechanism
IV
is the overturning of the structure, and its determinants are differential
settlement and angle of rotation of the foundation. The results of soil
representation with (HSM) are close to that of (MCM) for both dense and
medium-dense soils, while the results of (HSM) exceed significantly (MCM)
in loose soils. The results also indicate that the acceptable distance of the
tower foundation from the crest of the slope is equal to half the width of the
.5), which cancels out the effect of the slope and
the foundation behaves as if it were on flat ground, which is also the
recommended distance for the construction of the tower safely and for the two
soils dense and medium-dense density, while avoiding the construction of the
tower on loose soils, depending on the permissible value of the angle of
rotation. Increasing the ratio of the embedment depth for the foundation
reduces the maximum settlement below foundation by a rate ranging from
(31.18-47.25) %.
