Author : K. Al-Shukur, Abdul-Hassan
journal of kerbala university,
2017, Volume 13, Issue 2, Pages 212-224
A 2D( Plain strain) wall ‒ backfill ‒ foundation interaction is modeled using finite element method by ANSYS to find the optimum design based on the principle of soil-structure interactions analyses. A concrete gravity retaining wall founded on random soil subjected to earthquake loads has been considered in this research. Earthquake records which are obtained from the records of Iraq for the period 1900-1988 are transformed as time‒history force. The optimization process is simulated by ANSYS /APDL language programming depending on the available optimization commands. The components of the optimization process are the objective function OBJ is to minimize the area of the gravity retaining wall, the state variables SVs are the stress, strain, and displacement of retaining wall, also the factors of safety and stability considered as a SVs, and the design variables DVs are the dimensions of the retaining wall. In order to specify random soil parameters in the built model, the random field theory is adopted to generate random C-∅ soil. The results show that the initial section of gravity Retaining wall that is provided according to initial variables is not representing the optimum section, which it is needed to present in sectional area equal to 37.41% in order to achieved all safety requirements . In other hand, it has been taking various heights of gravity retaining wall as 3, 4, and 5m, the results showed that when the height of gravity retaining wall is increased by 66.6% from (3 to 5m), the optimum cross-sectional area increases in a percent of (177.27%). Further, the comparison between the sub-problem (zero-order) optimization method and the first-order optimization method is demonstrated that the first-order optimization method is more economical and sensible. Also, from studying the effect of some parameters which angle of internal friction of back fill soil, angle of internal friction of foundation soil, foundation soil cohesion, and unit weight of backfill soil (∅_1, ∅_2,C,and γ_sb;respectively) is proved that the foundation soil cohesion (C ) is more important than the other parameters, while unit weights of backfill soil have little effect on optimum section. It is concluded that the finite element method simulated by ANSYS is efficient with the optimization process.