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The Study of Safety Factor based on the Variation of Soil Property Parameters in Shallow Foundations in Phitsanulok Area
Some parameters in the selection of proper factor of safety for the foundation designs are not always measurable, e.g., design experiences, nature of soil composition and its uncertainly, etc. But, some mathematical tools could be used to take this uncertainly into account.
In this research, the statistical and mathematical methods are taken to identify an appropriated factor of safety in which soil data may not know for certain. The study uses twenty six samplings of existing soil data in Phitsanulok downtown areas being tested by other agencies. The samplings are classified as clay (CL). Uncertainties of probability density functions. A case study is applied to the design of a square shallow footing with ultimate limit state and ground-surface water level.
Based on Chi-square, tests have found that the appropriated distribution function of submerged unit weight at Df = 2.0 meters is exponential, and Df = 2.5, 3.0 meters are triangular. The appropriated distribution functions of cohesions and ultimate bearing capacities are exponential. Coefficient of variance of ultimate bearing capacity is of 0.9 thus the recommended suitable factor of safety is 3.0