Pavement Reliability Analysis By Stochastic Finit Element Method

As the great development of road design methods and materials, pepole have a more scienticfic understanding in the road structural style,load as well as materials. Considering the factors'rabdomucity and instability which affect the road structure design and evaluation, scholars us the whole or partial failure probability to judge the structure reliability. This situation is becoming a main gist in design methods now. At present,the widespread methods are as following:first order reliability method,response surface method and monte carlo method. at the same time, many powerful numerical simulation computing sofewares are widely used in the the engineering reliability field and open up a new research field in the structural reliability analysis,such as taylor expansion stochastic finit element method,perturbation stochastic finit element method,newman stochastic finit element method and so on. all these methods have a lot of advantages in improving the applied range and results accuracy. In this article,we combined the conditional JC method and finit element method together and embed the basic formulas into the finit element constitutive equations in order to get the gradient of the road function and the final reliability index. They are three main aspect as following:(1) taking the deflextion and flextual stress at the bottom of each layer as the control index and considering the elastic modulus of each layer,admissible flexural strength and deflextion as the basic stochastic varibles for building the correspongding road structure function, program is finished by using the Visual Fortran computer language and being based on the intrinsic two-dimensional linear elastic finit element to compute the reliability index and sensitivity.(2)according to the reliability analysis of the typical semi-rigid roadbase, results show that as the increase of the elastic modulus of each layer,the reliability index is gradually increase and oppositely decreased as the increase of variability level of modulus of each layer. this type of road structure is more sencitive control index of flextual stress rather than defextion model.(3) aim at the road type of rubblized cement concrete slab with asphalt overlay, the sencitivity analysis is done about the status of before and after rubbilizing the cement concrete slab and overlaying the asphalt pavement in the reliability aspect.the results show that the coefficient for importance of asphalt overlay elastic molulus and base elastic modulus is greater than subgrade and crashed layer.also the elastic modulus of asphalt overlay play a most important role in the diversification of deflection and flextual stress.