Structural Design

enas saleh

5 months ago

Design Implementation of Pile Foundation

In general, the term foundation can be defined as the part of the structure which bears the weight of the structure as well as several direct and indirect loads, and transmits them to the underlying soil or rock. The process of designing a foundation involves geology, soil mechanics, rock mechanics and structural engineering. (Day 2005.) A Foundation is the connecting link between the structure proper and the earth. A foundation can also be defined as an artificially laid base on which the superstructure is built (Jumikis, 1971.) The principle aspect of foundation design is to identify the most suitable type of foundation, such as whether to use shallow or deep foundation for the proposed structure. Another fundamental aspect is to develop and understand the governing parameters such as the bearing capacity of the soil or rock underneath and the estimated settlement of the foundation over time. The design of a foundation structure also involves the reinforcement detailing which includes the diameter of the reinforcement bar, the steel grade and the spacing between the reinforcement bars. In most cases, the design of a foundation involves both a geotechnical engineer and a structural engineer. In the initial phase, the geotechnical engineer provides the details regarding the soil bearing capacity and the structural engineer performs the actual design of the foundation. The fundamental structure of the foundation can be divided into two broad categories i.e. shallow foundation and deep foundation. Further, these two types can be divided into several sub-categories depending upon their physical form and structural properties. The geotechnical works and initial planning phase depend upon factors such as the surrounding structures, previous history of the site, and corrosivity levels. (Day 2005.)

The first step in the design of a foundation requires some basic knowledge about the location of the site, known geological hazards, fault lines, landslides or deposits of lique-faction prone sand which is not common in Finland. The knowledge about the projects size also helps in the initial planning phase to avoid budget over-runs. The determination of the scope of the work, such as possible subsurface exploration, laboratory testing to determine the feasibility of the project and compaction testing, minimises any possibility of surprise shortcomings during the actual design and construction phase. For a simple structure, the design and construction could be fully based on the preliminary design in most cases, but for large scale projects, the initial design and plan could be optimised as design and construction progress. (Day 2005.)

In Finland, the most usual concern while designing the foundation used to be the frost protection. Since the bedrock level can be found within a very comfortable piling range, the load bearing issues are usually simple. Primarily in Northern Europe, the foundation is done to mitigate the effects of frost penetration adequately. If this problem is ignored, it may cause damage under and around the foundation, which could require a costly repair procedure. In general, the depth of the foundation should extend well below the depth of frost penetration level in frost-susceptible soil. (Farouki 1992.)