Establishment of analysis method for crack growth in concrete and rock

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A general analysis method for crack growth in concrete and rock is developed. A finite element with displacement discontinuities is formulated. Along the discontinuities a tension-softening relationship is satisfied and bifurcation into the unloading path from the tension-softening path is judged. As a result, the localization of cracking, for example in a beam without an initial notch under bending, can be captured by the proposed method.A back analysis method is developed to determine the tension-softening curve from a load-displacement curve obtained in, for example, a bending test of a notched beam. The tension-softening curve represents material properties on tensile fracture. Direct tension test is difficult to conduct, and the proposed method provides a solution to the problems in the practical application of fracture mechanics.Based on the developed analysis method and back analysis method for tension-softeing curve, a design method of tunnel lining with SFRC (steel fiber reinforced concrete) is proposed. The cross-sectional capacity is estimated based on fracture mechanics of concrete.