The Influence of Initial Saturation on the Slurry-Bled Water-Seepage Law of Isolated Overburden Grout Injection

Abstract

The grout injection forms a compacted backfill in the separation chamber, and most of the grouting water seeps into the overburden pores. The initial saturation of overlying rock has been found to affect the seepage distribution of effluent in overlying rock. In the actual grouting process, the flow direction of grouting water in overlying rock and the initial saturation of overlying rock may affect whether the bled water will leak to the working face. In order to investigate the influence of initial saturation on the seepage law of isolated overburden grout injection, the present paper studies the saturation change process of bled water seepage at three different initial saturations (Sr = 29%, 51%, 73%). The water leakage of the working face was monitored with the self-developed 3D visual simulation experimental system, without considering the overlying rock of the injection layer. The results show that the bled water flows mainly in the horizontal direction, and the horizontal seepage velocity is about 10 times the vertical seepage velocity. The higher the initial saturation of the overburden, the larger the seepage range of the overburden, and the closer the seepage boundary is to the working face, the easier the bled water will leak into the working face. Therefore, the grouting design and process control can be carried out better. When the thickness of the selected isolation layer is insufficient, the bled water may appear on the working face, so this problem can be improved by increasing the thickness of the isolation layer.

Keywords

• grout injection
• seepage
• initial saturation
• physical simulation