Abstract: A method for constructing a fixed monitoring pile for a mining area with a high phreatic water level includes: S1: prefabricating a pile foundation body, where the pile foundation body has a columnar structure, and a plurality of extension connection ports are provided at an outer side and a bottom of the pile foundation body; and S2: digging a foundation pit at a designated monitoring point; combining the pile foundation body with an extension body to form a fixed monitoring pile; placing the fixed monitoring pile into the foundation pit, such that a bottom extension body and a side extension body are inserted into the pit foundation; and backfilling and compacting. The method increases the affinity between the fixed monitoring pile and a loose layer and strengthens the fixed monitoring pile to prevent it from loosening, thereby improving measurement accuracy.

Abstract: A method for dewatering a coal mine goaf by crossing a neighboring goaf is applicable to a scenario including a first goaf, a second goaf, and a third goaf located sequentially at one side of a roadway. A directional hole mechanism is provided between the roadway and the second goaf as well as between the roadway and the third goaf. The directional hole mechanism passes through a coal seam floor at a bottom of the goaf and is communicated to the second goaf and the third goaf. The directional hole includes a first directional hole and a second directional hole. The first directional hole is communicated to the second goaf, the second directional hole is communicated to the third goaf, and the first directional hole is provided with a casing structure.

Abstract: A method for constructing a fixed monitoring pile for a mining area with a high phreatic water level includes: S1: prefabricating a pile foundation body, where the pile foundation body has a columnar structure, and a plurality of extension connection ports are provided at an outer side and a bottom of the pile foundation body; and S2: digging a foundation pit at a designated monitoring point; combining the pile foundation body with an extension body to form a fixed monitoring pile; placing the fixed monitoring pile into the foundation pit, such that a bottom extension body and a side extension body are inserted into the pit foundation; and backfilling and compacting. The method increases the affinity between the fixed monitoring pile and a loose layer and strengthens the fixed monitoring pile to prevent it from loosening, thereby improving measurement accuracy.

Abstract: A level instrument for surveying a mining subsidence zone in a coal mining area includes a bottom plate, a leveling mechanism, a lifting mechanism, and a level instrument body, where the leveling mechanism is provided on the bottom plate, the lifting mechanism is provided on the leveling mechanism, and the level instrument body is provided on the lifting mechanism. A surveying method using the level instrument is further provided. The level instrument is placed at a surveying location through the bottom plate, a levelness of the level instrument body is directly adjusted through the leveling mechanism below the level instrument body, and a height of the level instrument body is directly adjusted through the lifting mechanism. In this way, the operation process of the level instrument is simplified, and the overall surveying efficiency is improved.