Abstract

In the design of underground tunnels and caverns located in weak rocks, grouting plays an essential role. Grouting is a complex process demanding high degree of skill and knowledge in understanding of grout flow and requirements for certain geological conditions. This paper discusses a design of grouting in underground caverns with an aim to improve the stability of the structure and to reduce water inflow into the cavern through sealing of fractures. Estimation of grouting efficacy becomes an important part of any grouting since there is high degree of uncertainties involved in the interconnectivity and condition of fractures inside the rockmass. Therefore, two different trial grouting programs are devised, and their results are discussed in order to arrive at a robust grouting scheme. The systematic approach of both programs involves pre and post grouting investigations. One approach is based on multi stage grouting with efficacy check through Water Penetration Tests (WPT), Borehole Televiewer test and Seismic Refraction Test. Second approach is based on single stage grouting with efficacy check using WPT, Core logging and cross hole velocity tests. The analytical estimates of grout intake and penetration length are compared with actual grout intake in both trial programs. An understanding of the grout behavior is developed to arrive at a final grouting scheme for the given geological condition. This work shows the importance of state of art in the development of a grouting process based on geological and hydrogeological conditions and can be helpful in grouting design for underground tunnels and storage caverns.

This content is only available via PDF.
You can access this article if you purchase or spend a download.