Evaluation of rock mass improvement due to cement grouting by Q-system at Bakhtiary dam site

• Improvement of Q-system parameters due to grouting was evaluated.
• Deformation modulus based on the Q-logging in boreholes before and after cement grouting was compared with in-situ measured modulus.
• Good agreement has been achieved between measured and estimated deformation modulus.
• Applicability and efficiency of Q-logging for estimating of deformation modulus for grouted sites were shown.

In this research, Q-logging system was developed based on the cores drilled at the grouting panels to investigate the influence of the cement grouting on the rock mass properties at the Bakhtiary dam site. In this way, rock masses in the different boreholes at the grouting panels were classified using the Q-system. Then, using the experimental equations, rock mass deformation modulus (Erm) was calculated for each borehole. In order to evaluate this method, value of the rock mass deformation modulus was also obtained by the dilatometer test results. The outcomes display that the Q-logging system can be used as a practical and undemanding method in evaluation of rock mass quality by the grouting treatment.