Reliability Analysis Of Bearing Capacity Of Cement Injection Pile Composite Foundation In Loess Areas

The research of reliability started as early as 30's in 20th century, which was applied in structure design about 40's and later in geotechnical engineering. Because of so many uncertain and unknown factors in geotechnical engineering the application of reliability theory in resolving geotechnical engineering problem is more difficult in the research of engineering reliability analysis, especially for composite foundation.The cement injection pile composite foundation has been already applied in practice in loess areas and has produced considerable benefits for economy and society. But, the method of its reliability analysis is not perfect yet, and the study of its reliability of the bearing capacity is also very poor.Based on the past researches, this paper introduces the essential features and main methods on reliability analyses of geotechnical engineering. Since traditional certainty methods have some instinct limitations, in this paper, according to the bearing capacity of composite foundation, the reliability probability model is given and the JC method is used to study the reliability index of primitive design safety coefficient method. First, the mean and variance of the bearing capacities of the cement pile and the soil between the cement piles are ascertained after analysis, and so the probability characteristic of the composite foundation is deduced. Then, the state equation of bearing capacity of composite foundation with cement injection pile was constructed and the probabilistic models of other parameters treated as stochastic variables were analyzed. Finally, structural reliability theory is used and combined with real projects, examples are used to illustrate the calculating process. In the paper, the reliability analysis method of the bearing capacity of cement injection pile composite foundation is investigated and by studying actual engineering examinations, some disciplinary conclusions are also elicited. It will offer some reference and evidence to the reliability design method of composite foundation, set up the theory frame for it and push the developing of it.