Based On The Random Field Theory Of Pile Foundation Stability Reliability Research

Reliability problems in geotechnical engineering research has become the rapid development of a discipline in many countries, the first is the basis of reliability analysis of geotechnical engineering to determine the probability of model parameters.The traditional probabilistic method in vestigated parameters as independent random variables, ignore the autocorrelation characteristics of the soil in vestigated, cause of localized parameter variance estimation slants big, make small calculate reliability index, the corresponding failure probability is larger.So in the actual main difficulties that exist in the geotechnical engineering reliability analysis method is to use traditional probability of reliability index is low and the huge difference between the actual situation.If in the process of reliability problems in geotechnical engineering research, the geotechnical parameters of soils is in vestigated as research data in a single random variable, so that the results obtained will be conservative, geotechnical engineering should be localized parameters of discretization, give localized parameters with the characteristics of the airport, the geotechnical engineering problems research introduced the concept of random field, this is not only the trend of the study of geotechnical engineering problems, also can give engineering and geotechnical engineering reliability research into new areas.In this paper, in the study of pile foundation pile reliability stochastic finite element model is adopted to improve the reliability of pile foundation study, using the CPT(static sounding data to determine the random field model characteristic parameters) thus pile foundation engineering stochastic finite element model of the single pile is established.On this basis, combining with the theory of structural reliability analysis, by using the ANSYS finite element analysis software to practical engineering modeling and applies the ANSYS finite element method for calculating the credible degree that the PDS module for reliability calculation of the single pile.In the process of calculation using the monte carlo method combined with finite element software ANSYS to affect the stability of pile foundation reliability index of the random sampling and input and output variables to 2000 times more accord with the engineering practice of the vertical ultimate bearing capacity of single pile reliability index.Through correlation analysis, the reliability design for pile foundation in all the influence factors of effecting the reliability of pile foundation, pile top load value of size effect on the displacement of pile top is most obvious, in addition, the bottom of piles modulus of elasticity and side piles modulus of elasticity and the influence of pile lateral poisson's ratio effect is more obvious, and it will conform to the geotechnical engineering problem of statics analysis theory.By using JC method for calculation of pile foundation reliability index and the finite element ANSYS calculated results to compare with the airport, it is concluded that in the pile foundation engineering numerical calculation of finite element model not only considers the localized parameters of spatiality and corresponding to reality even more is considering the correlation of the localized parameters, made for the actual pile foundation engineering reliability index increases, failure probability decreasing.Also better reflect the reliability calculation for the pile foundation engineering in the process of if you ignore localized with the airport, will be cause for the actual project and the smaller the value of reliability index, so the stability of geotechnical engineering, especially the pile foundation engineering random field theory the reliability of the research is not only a theoretical study on geotechnical engineering problem of practical application will also have a positive impact on actual pile foundation engineering design.