Experimental research on the influence of stratum permeability on the time-varying properties of active grout

In the construction of underground projects, the water-binder ratio is generally considered as one of the main factors affecting the cement-based backfill grouting performance. In addition, when the backfill grouting is consolidated in the formation. The difference in the permeability of the formation will affect the consolidation rate and consolidation drainage of the backfill grouting, resulting in changes in the water-binder ratio of the grout, which in turn affects the development of its performance after consolidation. However, it is difficult to simulate the consolidation and hardening process of backfill grouting in the formation with the current indoor test equipment. Therefore, the influence of the permeability difference of the stratum on the time-varying law of backfill grouting and consolidation is less studied. In this paper, the self-made consolidation test device is used to study the time-varying law of grout consolidation in different permeable formations, and the time-varying law of grout performance is studied by using the samples after consolidation. The results show that with the increase of formation permeability coefficient, the dissipation time of excess pore water pressure of grout decreases, and the volumetric strain increases. The grout consolidation rate is determined by the relative permeability coefficient between the grout and the formation, and the difference in consolidation causes changes in the moisture content of the grout after consolidation. The change of the ratio of bound water to free water affects the time-varying law of strength after consolidation.