Investigation of construction-joint grouting techniques under field conditions

Conclusions

• 1. For preliminary assessments of the standard of joint grouting, use can be made of the results of expanded water testing, with the air outlet closed and open, respectively. In analyzing the water-test results, it is convenient to examine the grouting networks by dividing them into two groups according to their hydraulic penetrability: those which meet, and those that do not meet, the requirements stated in the Technical Standards (TS) for grouting joints.

• 2. The consumption of water in grouting networks, obtained when water testing with the air outlet closed, does not determine the watertightness of the peripheral seal installed for grouting purposes. In our opinion, the grouting network can be regarded as watertight provided the condition is met whereby the discharge diminishes and rises with the corresponding injection pressure.

• 3. An analysis of water-test results, conducted on 79 grouting networks of intercolumnar joints of the dam of the Sayano-Shushenskoe hydropower scheme, indicates a sufficiently satisfactory standard of installation of the embedded grouting fittings, the watertight design of the grouting network, and of smooth surfaces of the construction joints. This is verified by the close values of the pressures at the inlet and outlet of the grouting network and of the supplementary displacements of the joints, which develop even at low injection pressures.

• 4. The analysis carried out on the supplementary opening of construction joints during water testing, grouting, and the post-grouting period (2 h after the work has been completed), indicates that the most favorable grouting technology has been maintained. The technique is verified as the means for the successful monolithization of the dam section.