Study On Reliability Of Composite Pile Foundation

Based on the research on composite pile foundation and the theory of reliability, this paper developed systemic and embedded study on reliability of composite pile foundation by using theory of probability limit states design. Content which is involved in this paper are as follows: fundamental method of reliability analysis, statistic on probability character of typical soil layer in Hexi area of Nanjing, analysis on reliability by using the method of ultimate bearing capacity of single pile, contribution on reliability by model of composite pile foundation broken which gain â–³fu that bring into by soil flowing around pile, based on the calculation method of settlement, reliability model of settlement has been established, Controlled state and conversion condition has been confirmed by design method of strength and deformation, Many programs are worked out in MATLAB language .In this thesis, the influence factors upon reliability index B are investigated and some valuable conclusions are drown. Five main parts of this paper as follows:1. Firstly, this paper introduces the essential features and main methods on reliability analyses of geotechnical engineering. In respect to the geometry method, more concision programs are worked out.2. Generalizing the method of probability statistic that based on the model of random field, this paper draws some comparison by using 3 o principle. This paper also first study on the typical soil self-correlation distance in Hexi area of Nanjing and give the self-correlation distance value of soft soils.3. Based on design method in ultimate bearing capacity of single pile of composite pile foundations, combined with a real project, structural reliability theory is used to analyze reliability of formula of the ultimate bearing capacity by using this method. Further research is carried out on aspect such as sensitivity of basic variables, the relationship between index of reliability and safety factor aim at combination of different coefficient, the contribution to reliability with the change of each coefficient, and so on. This paper also ensures the range of using coefficient of bearing capacity of nature foundation.4.Further research is carried out, such as â–³fu which is brought in soil sliding the piles effect on reliability, sensitivity of soil index effect on reliability, and so on . This paper also ascertain the factor of adding reliability.5. Based on the settlement calculation method of composite pile foundation, calculation model in compressive area method of reliability is established, and simplified calculation model is presented. Combined with a project example, comparative analysis shows practicality by using this method. Further research iscarried out such as variability coefficient of the soils modulus influence on reliability of settlement.6. Model of reliability analysis is established in both bearing capacity and settlement. The main controlling state of reliability design method of composite pile foundations is confirmed, and simplified analysis method is put forward. This article also makes certain the feasibility of optimizing number of pile in reliability Analysis.