Case Study on the Method of Rock Mass Overburden Consolidation Grouting for Dam Foundation

Conventional grouting methods present challenges in achieving effective surface rock grouting and avoiding interference with concrete grouting and construction processes. The proposed approach includes reserving rock overburden, controlling grouting pressure and concentration, using a segmented grouting method, and selecting appropriate materials to develop a key method for consolidation grouting. This method not only overcomes the problems associated with the conventional consolidation grouting method but also effectively protects the thin layer of breccia lava in the Baihetan Dam foundation and solves the problem of unloading and relaxation of columnar jointed basalt caused by exposed consolidation grouting. The results show that the post grouting inspection hole permeability qualification rate is 99.3%, with the proportion of high-speed measuring points of various rock types ranging from 91.8% to 93.3%, and the proportion of low-speed measuring points ranging from 2.0% to 2.9%. The drop rate of the grout take of sequence I and sequence II is between 30%–60%, except for some dam sections. These results indicate that the proposed method for consolidation grouting meets the design requirements. The findings have significant implications for the design and construction of consolidation grouting in similar projects.