كيانا قاسمي پورمياندهي

The use of non-connected pile-raft foundations has become popular due to the more economical design of the connected pile-raft foundation. Considering the increasing use of this type of foundations, as well as the use of piles made with soil improvement methods such as sand columns or soil-cement columns (that are implemented using methods such as deep mixing or jet grouting), eva‎luation of the effect of the material properties of each of the pile-raft elements on the behavior of the non-connected pile-raft system can be useful for more accurate and economical design of the non-connected pile-raft with soil improvement columns. The aim of this numerical research is to study the behavior of non-connected pile-raft system with soil improvement columns using Abaqus finite element software . In this research, the effect of changes in the modulus of elasticity of the subsoil, cushion, and soil improvement columns in two groups of models with floating piles and end-bearing piles has been investigated. The dimension of the solid raft is 1.5 × 7.5 × 7.5 meters and the thickness of the cushion is 0.8 meters. Also, soil improvement columns with a diameter of 0.8 meters and a height of 15 meters have been considered in the form of a 3×3 grid. In order to reduce the analysis time of models, one fourth of the model has been modeled in Abaqus software and symmetry boundary conditions have been applied to the symmetry boundaries. The loading applied to the numerical model is in the form of applying compressive stress to the raft foundation in the amount of 8 tons per square meter . The results of numerical modeling showed that due to the rigidity of the raft, in both floating and end-bearing pile-rafts, the stress generated in the corner piles is the highest and the middle piles are the lowest. eva‎luation of the load-settlement behavior of the models shows that with the increase in the modulus of elasticity of each element of the non-connected pile-raft system, the settlement decreases at all parts of the system. Also, the investigation of the stress concentration coefficient in both floating and end-bearing systems shows that with the increase in the modulus of elasticity of the subsoil, the stress in the pile heads decreases and in the subsoil increases, but the increase in the modulus of elasticity of the soil improvement columns and the cushion leads to an increase in the stress concentration coefficient values of soil improvement columns and the subsoil. Keywords: non-connected pile-raft, soil improvement column, modulus of elasticity, stress concentration, load-settlement behavior

راديه شمع غيرمتصل , ستون بهسازي خاك , مدول الاستيسيته , تمركز تنش , بار نشست

non-connected pile-raft , soil improvement column , modulus of elasticity , stress concentration , load-settlement behavior

Kiana Ghasemi Pour Miyandehi

Dr. Mohsen Sabermahani