Study on Key Technology of Floor Grouting in High Confined Water and Thin Aquiclude
Gao, Weifu (1,2); Han, Jin (3); Han, Lu (4)
1: Department of resources and civil engineering,Shandong University of Science and Technology, China, People's Republic of; 2: National Engineering Laboratory for Coalmine Backfilling Mining, Shandong University of Science and Technology, Tai’an 271019,
In recent years, with the increasing depth of coal mining in eastern China, the lower coal seam is threatened by water inrush from coal seam floor due to high confined water and thin aquiclude. How to safely exploit coal seams threatened with higher confined water is an urgent problem.
In order to prevent water inrush from coal seam floor, in this paper, some new technologies were adopted to treat the working face floor. Firstly, the Ordovician limestone was stratified by exposing the drill hole statistics. Secondly, the grouting thickness of Ordovician aquifers was deduced based on water inrush coefficient method. Finally, using the mine 3D Electric Resistivity Tomography（ERT）, the grouting hole adopted small angle and three-stage casing technique to explore the grouting effect.
Based on borehole exposure, the Ordovician limestone aquifers were divided into overlying strata, grouting layers and bottom layers. And the intermediate layers provided places for Ordovician limestone grouting. The grouting thickness of Ordovician limestone provided a theoretical formula for calculating the grouting volume of the floor. Through the small angle and three-stage casing technique, we ensured that the Ordovician limestone aquifers were targeted grouting. Using 3D ERT is not only visualized and intuitive, but also convenient for delineating abnormal grouting area, further grouting and ensuring grouting effect.
The example of grouting in Feicheng mining area shows that the technology not only ensures the safe mining of working face threatened by water inrush from coal seam floor, but also prolongs the service life of old mines in eastern China.