Abstract: A new method for determining nonlinear fracture toughness of frozen soil is presented based on the method of J integral as well considering nonlinear behavior characteristics of frozen soil. It is well known that J integral can be expressed as J =Je +Jp, in which Je represents elastic component and Jp represents plastic component. The calculation of Je is relatively simple, but the calculation of Jp is quite difficult. Because in the process of calculating Jp, one parameter Up, which represents the plastic work of sample, is very difficult to determine. To simplify the calculation, rewriting Jp as an expression of Je, Jp =qJe, then J integral expression becomes as J=(1+q)Je. That means when Je and factor q are determined for one kind of sample, J integral can be gotten easily. This method is named as correction-factor method. The correction factor q is obtained by increments of load and displacement according to curve of load vs. displacement (P-Δ curve), in which includes two cycles of loading-unloading. Using the suggested method, nonlinear fracture toughness of frozen soil in-situ is determined; and the results in comparison with the data of related literature show its reasonableness and availability.

Key words: frozen soil, nonlinear fracture toughness, J integral, correction factor