Abstract: This paper develops a new comprehensive evaluation method of grouting quality with multi-indices synergy, to solve the problem that the traditional evaluation methods rely on a single index and suffer poor capability of reflecting the behaviors of grouted rock mass. First, we construct an index system with four indicators: post-grouting Lugeon value, rock wall integrity index, acoustic wave speed, and unit grout consumption, in order to evaluate the dual criteria of permeability and compactness. Then, we use an analytic hierarchy procedure and the entropy weight method to calculate subjective and objective weights separately, and combine the weights to balance expert experience and data characteristics through applying the game theory. Finally, we achieve the quantitative grading of grouting quality by constructing a membership degree matrix based on the fuzzy comprehensive evaluation method. Application to a hydropower station project in Southwest China shows a comprehensive evaluation weight vector of [0.396, 0.2655, 0.1658, 0.2091]T and the grouting quality indices of 4.307, 3.769, 4.356, and 4.365 for the four evaluation units respectively. Compared with the traditional single-index method, this new method gives the same overall trend of grouting quality, but can identify local weak grouting areas with higher accuracy. This study demonstrates the advantages of multi-indices synergy, rational weighting, and robust evaluation of our new method, and lays a basis for better grouting quality assessment and supplementary grouting decision-making.

Key words: grouting quality evaluation, rock wall integrity index, combined weighting, fuzzy comprehensive evaluation, curtain grouting