Experimental Study on Grouting Effect and Mechanical Properties of the Rockfill Materials Grouted with SCM

Insufficient compactness of rockfill materials may potentially cause excessive deformation of a concrete face rockfill dam (CFRD), thus resulting in cracking of the face slab and leakage of the dam body, thereby requiring reinforcement treatment. To date, there are no effective measures in strengthening rockfill materials. In this study, self-compacting mortar (SCM) was applied to the Shibaozhai CFRD in Gansu Province, China, to test the effectiveness of grouting reinforcement. Simultaneously, an indoor triaxial shear test was conducted to investigate the changes in the mechanical properties of rockfill materials before and after the grouting reinforcement. The on-site test results showed that the rockfill reached the desired porosity after grouting and grouting reinforcement enhanced the cementation degree of rockfill materials while maintaining uninterrupted drainage capacity, which met the requirements of rockfill grouting for the face rockfill dam. The results of the triaxial shear test indicated that the cohesive force of the rockfill materials rose by 3.95 times and the modulus increased by 7.24 times after grouting reinforcement，significantly enhancing the mechanical and deformation properties of the rockfill. An increase in the content of coarse particles was shown to enhance the stability of cementitious structures, which leads to a better skeleton effect and thereby raises the effectiveness of the grouting reinforcement. The rockfill materials also exhibited strain-softening characteristics following the grouting reinforcement. The research showed that grouting reinforcement technology is suitable for managing the deformation of high CFRDs or reinforcing ill rockfill dams.