Roof drainage and grouting reinforcement works for cross-ditch mining works on the working face in Halagou Coal Mine, Shendong mining area, Shenhua Group
1. Introduction
In working face 22206 of Halagou Coal Mine, Shendong Mining Area, Shenhua Group, there are two branch ditches of Sanyuan ditch. The maximum height of caving zone can develop to the loose layer, and the water-conducting fracture zone can develop locally to the surface. During the mining process, water is diverted from roof aquifer into the mine through the water-conducting fracture zone and the loose sand layer, will flood the mine with the water flow, resulting in water and sand collapse accidents, which will affect the work safety of the mine.
2. Treatment solution
In order to prevent and control water and sand collapse accidents, the following measures were taken:
(1) Draining and depressurizing holes were arranged in the areas with relatively thin roof bedrock, which could reduce the head height of loose aquifer of the overlying bedrock by draining water from roof, thus reducing the probability of water inrush and sand collapse to a certain extent.
(2) Grouting consolidation was carried out in the loose layer by using the hydrophobic depressurization hole, so that the loose layer was consolidated into a block by means of grouting, and the amount of water gushing and sand breaking in the roof caving zone during mining in the working face was reduced.
3. Construction situation
Boreholes were drilled from the roof of roadway, through the overlying bedrock, and to the final depth in the loose aquifer. The final holes were arranged in a regular triangle with a spacing of 10m and a drainage and grouting area of 10797.7m2. 161 boreholes have been drilled.
4. Achieved accomplishment
Through drilling and coring in the treatment area, according to the comprehensive judgment of slurry content, cementation and strength in the core, the grouting effect is good, meets the requirements of safe mining in the working face.
According to the mining works, there is no water and sand break that affects the production in the mining area, and the grouting effect is obvious, which achieves the goal of treatment.
5. FAQ
(1) What are the difficulties in this project?
A: The difficulties in this project are the construction technology, which mainly include two aspects: I, the conventional drainage boreholes are easy to collapse, resulting in unsatisfactory drainage effect, so how to improve the drilling technology is one of the difficulties of this project; II: how to ensure the grouting effect after drainage.
(2) What are the technical problems that need to be further solved in this kind of project?
A: The technical problem that needs to be solved further is: At present, most of this kind of projects are assessed by empirical analogy method, which cannot accurately assess the risk of water and sand break. Therefore, in the next step, it is necessary to adopt various means to assess and reasonably determine the scope of treatment.
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