Study On Cement Pavement Structural Reliability Assessment Methods

Cement pavement is a main form of highway pavement, and it is generallybelieved that the cement pavement has good durability, so the design life ofcement pavement is very long. However, cement road has been built, oftenappear cracking, slab breaking boards and other diseases before design life. Thisindicate that cement pavements we built are lack of reliability. The structuralparameters, environmental factors and traffic loads of cement pavement areuncertain, so that the life of the pavement structure comes to be a randomvariable. Therefore it is necessary to study the reliability of cement pavement.Frist, thickness and modulus of cement pavement layer, and trafficparameters distribution and range of variation have been analyzed. It is provedthat they generally have a lognormal distribution of non-negative characteristics,while the level of variability is decided by the level of construction control. Thevariable coefficients of structure are increasing as the pavement structure comeinto service. In view of this, the Monte Carlo sampling methods combined withfinite element model is used to compute the reliability of cement pavementSignificance analysis of the various design parameters on pavement reliabilityshows that the surface layer concrete flexural strength make the greatest impacton the pavement reliability, followed and thickness of the surface layer, whileeffect of modulus of basic is relatively less.Finally, the effect of base and subgrade performance degradation and baseuneven supporting on pavement structural reliability, The results showed thatwhen base modulus cut in half, coefficient of variation increased0.05, pavementreliability decreases by about3%,while halving subgrade modulus, coefficientof variation increased by0.1, the road reliability decreases by about21%. Whenvoid region appeared at the midpoint of the longitudinal edge of the slab,pavement reliability reduce significantly. Because spatial variability existspavement materials, how base simplified2D random distribution characteristicsinfluence on pavement reliability has been analysed, the results indicate thatcosiding material parameters as a single make a higher probability of failure.