Numerical analysis of notch-cutting method for determining the residual stress in PCC Slab

The existence of residual stress and built-in curling will result in the multi-cracking modes in portland cement concrete (PCC) slab and produce profound influences on the long term service behavior of JPCP. It is still in the preliminary step to determine the initial stress and residual stress inside the slab by measuring the surface strain release history during cutting notch. Three dimensional finite element models were established to simulate the slab's responses to notch cutting under different conditions such as measurement position, boundary constraint modes, foundation stiffness, slab thickness, notch space, notch depth and temperature field components, etc. On the basis of these data, a full depth absolute stress and residual stress profile prediction procedure using dry notch cutting method is presented. Notch depth-space ratio is taken to consider the overall effects of notch space and notch depth on stress and strain relaxation curve. Ultimate relieved strain is introduced to characterize the influences of slab size, thickness, temperature field components and the underlying stratum. The basis functions and corresponding parameter values that represent the slab surface strain relief features are listed. The reliability of this procedure is verified by a numerical example of a full scale slab. The eventual notch depth-space ratio is recommended to be in between 1.0 and 1.5 and slab thickness-notch space ratio is advised to be larger than 1.25 in experiments.