Behavior of concrete jacked piles on collapsible soil

• Grant number: 08/04714-0
• Support Opportunities: Regular Research Grants
• Start date: August 01, 2008
• End date: July 31, 2009
• Field of knowledge: Engineering - Civil Engineering - Geotechnical Engineering
• Principal Investigator: Cláudio Vidrih Ferreira
• Grantee: Cláudio Vidrih Ferreira
• Host Institution: Faculdade de Engenharia (FE). Universidade Estadual Paulista (UNESP). Campus de Bauru. Bauru , SP, Brazil

Abstract

The region of Bauru, in the center of the Sao Paulo State, Brazil, is typically covered by sandstone of Bauru Group. The subsoil upper layer is unsaturated constituted by reddish and dark brown, fine clayey sand. This residual soil has suffered a pedogenic process, which result in a macro-voided structurally unstable soil. In this region innumerous old constructions had undergone damaging differential movements due mostly to increase in moisture content of the foundation soil. A common remedial measure for buildings that are settling excessively is to reinforce the existing foundation using jacked segmental pre-cast concrete piles. These piles, usually named "estacas mega" consist of cylindrical concrete piles segments having length of 1,0m and diameter of 0,20m. The pile is built up of sections which are pressed into the ground by a hydraulic system. The existing building supplies the reaction necessary for this. This method is used frequently; however, approaches to the design of these piles, in this type of soil, are not well developed. The author of this research project believed that Pile-load tests are the most reliable and informative source of soil-deformation properties required for a successful foundation design, therefore the author proposes this research project consisting in the realization of 12 pile-load tests in 6m and 8m length jacked piles, in order to verify the design assumptions and load-carrying capacity of the piles. The tests will be conducted in the experimental field of the School of Engineering of Unesp, in the city of Bauru-SP, Brazil, with the soil in the natural condition and after soaking with water before loading, in order to evaluate the influence of soil collapsibility in the results. The author expects that this work will supply this deficiency on the regional knowledge of this type of reinforcement of foundations and will be of assistance in further studies on the subject. (AU)