Abstract: In previous research of adaptive analysis using Numerical Manifold Method based on independent covers, the internal error in an independent cover cannot be effectively controlled. In view of this, a submodel method for error analysis of independent covers is presented, in which, by means of increasing the cover function order in an individual independent cover, a new error estimator for point-by-point error is obtained by calculating the differences of the results between high-order and low-order cover functions. The procedures of the submodel method are introduced in detail, and a case study of a gravity dam shows that the method could effectively control the internal error of independent covers, laying foundation for point-by-point error control in the future. Finally some preliminary theoretical analysis and discussions are given for the convergence principle and the error-control method of Numerical Manifold Method based on independent covers.

Key words: Numerical Manifold Method(NMM), independent covers, error analysis, submodel method, adaptive analysis