One of the purposes of consolidation grouting for dam foundation is to improve mechanical properties of rock masses. In this paper, we would like to discuss in situ experiment carried out in order to explore the grouting effects of rock masses on mechanical properties. This experiment is mainly consisted of operating, electromagnetic and elastic wave prediction and borehole expansion test.The results obtained through this study are listed as follows.o1.The change of permeability zone can be identified by change of electromagnetic wave amplitude.2.Further injection steps may help rock masses to become uniform in terms of electric characteristics.3.The change of elastic wave velocity by grouting injection also explains uniformity of rock masses.4.Grouting injection can improve deformability of rock masses.5.For more deformable rock masses before grouting injection, the more mechanical improvement will be expected.6.The rheological model explaining grouting injection effects can be verified. This model shows a tendency that poor rock masses which have lower mechanical properties, can be well expressed the experiment results.