Experimental study on the mechanical properties and creep development of loess grouting reinforcement material

The focus was on studying the effects of loess-based grouting material proportioning, fractured rock mass grading, overlying load, and grouting pressure on the grouting reinforcement effect of the fractured rock mass. The results showed that when the water-to-solid ratio was controlled at 1:1.4-1:1.0, the solid phase ratio was 3:7-5:5, and the water glass content was 3-5%, the slurry properties met the requirements for grouting treatment in the goaf. Through grouting reinforcement tests, it was found that as the strength of the grouting material increased, the crushing gradation decreased, the overlying load increased, the grouting pressure increased, and the difference in mechanical properties between the grouting material and the rock block decreased. The compression failure mode shows a 'rock-like' characteristic, with cracks mainly extending along the 'rock-slurry-rock' bonding surface, followed by extending along the grouting solid body. The instantaneous strain and axial creep values first decreased and then increased during the graded loading process, and the creep rate first decreased rapidly and then stabilized. Finally, the long-term strength of the grouting reinforcement material was determined to be 2.1 MPa, accounting for 65-80% of the instantaneous strength.