engleski

Analysis and measurements of settlement for heavy loaded rigid footing

During the construction of digester for treatment of Zagreb city wastewaters, monitoring system of structure and foundation soil was established. Digester is a huge rounded structure founded on reinforced concrete slab with average contact pressure over 600 kPa. Monitoring system, consisting of inclinometer and deformeter in-stallations, tiltmeters, pressure cell and geodetic measurements, provided information of structure movement during the construction and filling phases. Obtained results indicate larger settlement in the area of foundation where geotechnical investigations registered layer of lower geotechnical characteristics. Most interesting measurements were inclinometer measurements under the foundation slab that indicated the radial spreading of weaker material. That phenomenon indicates the plastic flow of soil and was the main reason for detailed analysis of slab settlement. In the analysis very stiff foundation slab was considered as a rigid footing. In the practice, it is a common routine to calculate the settlement of rigid footing according to the analytical solution for linear-elastic half space. Today new numerical methods are developed solving the same problem using the finite elements. They can use constitutive equations of material that include plastic behavior. In this article, comparison of footing settlement is made for elastic soil by Boussinesq solution and by finite element method, and additional analysis was made for elastoplastic material with the same stiffness and corresponding strength parameters. Numerical results are also compared with measurements at the same position.

settlements; digesters; geotechnical monitoring; numerical analysis

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