Open-pit mine multi-bench up-dip mining filling method based on vertical grouting of mold retaining wall

Abstract

This invention discloses a method for backfilling in multi-stage upward mining of open-pit mines based on vertical grouting using geotextile retaining walls. On the flat surfaces of each coal bench above the mine entrance and above the designed final mining line, horizontal groove-shaped vertical retaining wall holes and shared venting holes are opened downwards. Fiberglass pipes are then inserted into these holes. After being cut into mine sections, flexible geotextile bags are lowered through the holes, and quick-setting backfill material is injected into the bags to form solid retaining walls and seal the mine entrance. Next, the horizontal groove-shaped vertical retaining wall holes of all coal benches above the mine are used as grouting holes to inject backfill material into the mine. The same method is used to mine and fill layers from bottom to top. This method achieves sequential sharing of retaining wall construction, grouting, and venting channels in multi-stage upward mining, enabling rapid closure of the mine entrance after mining is completed and improving the contact effect between the backfill material and the mine roof.

Description

Technical Field

[0001] This invention relates to a method for backfilling in multi-stage upward mining in open-pit mines, specifically a method for backfilling in multi-stage upward mining in open-pit mines based on vertical grouting of geotextile retaining walls. Background Technology

[0002] Open-pit coal mining technology utilizes parallel strip-shaped mining chambers to recover coal resources covered by slopes. As mining methods evolve towards multi-bench upward mining, the vertical stacking of mining spaces necessitates the filling of goaf chambers to ensure the stability of slopes and overlying strata. In multi-bench upward filling engineering practice, there are engineering parameter requirements at two levels: perforation pattern layout and the mechanical properties of the filling materials.

[0003] Firstly, there are the requirements for the timing planning of the borehole network system in multi-stage mining. The backfilling operation relies on the vertical passage from the surface to the mining chamber for retaining wall construction, material transportation, and ventilation. When using a shared borehole that runs through the entire profile, it is necessary to plan the pipe layout and cutting sequence of the borehole during the advancement of each stage to ensure the smooth descent of materials and the continuity of processes in adjacent stages.

[0004] Secondly, there are requirements regarding the contact state between the backfill and the roof. During the transformation of the backfill slurry from a fluid to a solid state, water secretion and volume shrinkage occur. This material characteristic leads to delamination cracks above the solidified backfill, affecting its support effect on the roof. Designing a backfilling process that adapts to the chamber environment and combines backfill level control with physical volume replenishment during the solidification period is a requirement for the development of multi-step endwall backfilling mining technology. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a method for filling in multi-stage upward mining in open-pit mines based on vertical grouting using geotextile retaining walls. This method solves the problems of shared vertical channels, rapid closure of mining chamber openings, and difficulty in coordinating filling, venting, and consolidation shrinkage compensation during multi-stage upward mining.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a method for filling in multi-stage upward mining in open-pit mines based on vertical grouting of retaining walls using geotextile bags. In the preparation stage of end-side mining, on each coal step plate located above the entrance of the mining chamber and above the designed final mining line of the mining chamber, horizontal groove-shaped vertical retaining wall holes and common vent holes are respectively opened downward to penetrate to the lowest mining chamber. Then, pluggable fiberglass pipes are inserted into the horizontal groove-shaped vertical retaining wall holes. Then, the cutting equipment is used to start cutting and mining at the first mining position of the lowest coal bench until the designed final mining line position is reached and the cutting equipment is withdrawn, at which point a complete mining chamber is formed; the flexible mold bag is lowered into the mining chamber through the horizontal groove-shaped vertical retaining wall hole above the mining chamber opening. The opening of the flexible mold bag is located on the coal bench plate. Quick-setting filling material is injected into the bag through the opening. After the quick-setting filling material in the flexible mold bag reaches the preset solidification state, the flexible mold bag forms a solid retaining wall and seals the mining chamber opening; Next, the horizontal groove-shaped vertical retaining wall holes of all coal steps above the first mining chamber are used as grouting holes. Filling material is injected into the mining chamber through the grouting holes. When the volume of the injected filling material reaches the calculated main volume, the common vent hole is converted into the tail grouting hole for synchronous grouting until the filling material reaches the preset liquid level. Use the same cutting, mining, and backfilling methods as the first mining chamber to cut, mine, and backfill the other mining chambers of the lowest coal bench until the last mining chamber of the lowest coal bench is cut, mined, and backfilled. Then use the same cutting, mining, and backfilling methods as the mining chambers on the lowest coal bench to cut, mine, and backfill the mining chambers of the next lower coal bench until the last mining chamber of the next upper coal bench is cut, mined, and backfilled. Before cutting and mining the uppermost coal bench, grouting holes are opened in the middle of the horizontal groove-shaped vertical retaining wall holes and the common vent holes of the mining chamber. Then, the uppermost coal bench is cut, mined and filled using the same method as the mining chambers of other coal benches.

[0007] Furthermore, the shape and size of the flexible mold bag are adapted to the shape and size of the cross-section of the mining tunnel opening.

[0008] Furthermore, a counterweight is provided at the bottom of the flexible molded bag.

[0009] Furthermore, a temperature sensor is provided on the side of the flexible mold bag facing the entrance of the mining chamber.

[0010] Furthermore, a liquid level sensor is suspended in the shared vent.

[0011] Furthermore, when the coal step is cut and mined, the fiberglass pipe inserted in the coal step is pulled upwards, and the bottom of the fiberglass pipe is higher than the top of the mining chamber.

[0012] Furthermore, when the cutting equipment cuts coal into benches, it cuts the bottom of the mining chamber into a concave shape.

[0013] Compared with existing technologies, this invention achieves sequential sharing of retaining wall construction, grouting, and venting channels in multi-stage upward mining by using horizontal groove-shaped vertical retaining wall holes that penetrate to the lowest mining chamber and a shared venting hole. This reduces the duplication of holes across different coal benches and improves channel utilization. The exposed state of the channels during the cutting process is controlled by insertable fiberglass pipes, preventing channel collapse or interference with cutting equipment operations. A solid retaining wall is formed by injecting quick-setting filling material into flexible mold bags, allowing for rapid closure of the mining chamber entrance after mining is completed. A preset liquid level is determined by using the shared venting hole in conjunction with a liquid level sensor, and the pre-reserved filling material in the grouting holes and shared venting hole compensates for consolidation shrinkage space, thereby improving the contact effect between the filling material and the mining chamber roof. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the upstream mining and backfilling distribution operation of the present invention; Figure 2 This is a schematic cross-sectional view of a single mining tunnel in the filling state according to the present invention; Figure 3 This is a schematic cross-sectional view of the state of the filling body in the mining tunnel and grouting hole after filling a single mining tunnel according to the present invention; Figure 4 This is a schematic diagram of the cross-sectional structure of the tunnel used in this invention.

[0015] In the diagram: 1-Flexible mold bag; 2-Counterweight block; 3-Temperature sensor; 4-Mining chamber; 5-Fiberglass pipe; 6-Horizontal groove-shaped vertical retaining wall hole; 7-Grouting hole; 8-Common vent hole; 9-Coal step; 10-Liquid level sensor; 11-Solid retaining wall; 12-Backfilling body; 13-Continuous mining machine. Detailed Implementation

[0016] The invention will now be further described with reference to the accompanying drawings.

[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] like Figure 1 and Figure 2 As shown, the present invention provides a technical solution, comprising the following steps: During the preparation stage of end-side mining, on each coal step 9 platform located above the entrance of mining chamber 4 and above the designed final mining line of mining chamber 4, horizontal groove-shaped vertical retaining wall holes 6 and common exhaust holes 8 are respectively opened downward along the direction perpendicular to the axial direction of mining chamber 4, penetrating to the lowest mining chamber 4. Then, pluggable fiberglass pipes 5 are inserted into the horizontal groove-shaped vertical retaining wall holes 6.

[0019] Then, using continuous coal mining machine 13 and other cutting equipment, the first mining chamber 4 of the lowest coal bench 9 is cut and mined until the designed final mining line position is reached, at which point the cutting equipment is removed, forming a complete mining chamber 4. During the cutting and mining of the coal bench 9, the fiberglass pipe 5 inserted in that coal bench 9 is pulled upwards, with the bottom of the fiberglass pipe 5 higher than the top of the mining chamber 4. For example... Figure 4 As shown, when the cutting equipment cuts and mines the coal bench 9, it cuts the bottom surface of the mining chamber 4 into a concave shape; the folded flexible mold bag 1 is lowered into the mining chamber 4 through the horizontal groove-shaped vertical retaining wall hole 6 above the opening of the mining chamber 4. The opening of the flexible mold bag 1 is located on the flat plate of the coal bench 9. The bottom of the flexible mold bag 1 is equipped with a counterweight 2, which allows the folded flexible mold bag 1 to unfold vertically inside the mining chamber 4. The shape and size of the unfolded flexible mold bag 1 are adapted to the cross-sectional shape and size of the opening of the mining chamber 4; then, quick-setting filling material is injected into the bag through the opening, and the quick-setting filling material inside the flexible mold bag 1 is ready to be injected. After the quick-setting filling material reaches the preset solidification state, the flexible mold bag 1 forms a solid retaining wall 11 and closes the opening of the mining chamber 4. In order to determine in a timely and accurate manner whether the quick-setting filling material has reached the preset solidification state, a temperature sensor 3 is provided on the side of the flexible mold bag 1 facing the opening of the mining chamber 4. After the quick-setting filling material is injected into the bag, the temperature value detected by the temperature sensor 3 will rise. When the temperature value detected by the temperature sensor 3 rises and then gradually falls back to the set temperature range, it is determined that the quick-setting filling material in the flexible mold bag 1 has reached the preset solidification state and the opening of the mining chamber 4 has been closed.

[0020] Next, the goaf 4 is filled. In order to ensure the roof closure rate, the nominal volume of the goaf 4 is calculated based on the goaf contour data. Based on the shrinkage rate parameter of the filling body 12, the volume of the supplementary filling body 12 required to maintain the fit between the filling body 12 and the roof of the goaf 4 is calculated. This volume is converted into the internal space volume of the grouting hole 7 and the common vent hole 8, and converted into a preset liquid level elevation parameter that is higher than a specified distance above the roof of the goaf 4. At the same time, a liquid level sensor 10 is suspended in the common vent hole 8.

[0021] During filling, the horizontal groove-shaped vertical retaining wall holes 6 of all coal steps 9 above the first mining chamber 4 are used as grouting holes 7. Filling material 12 is injected into the mining chamber 4 through the grouting holes 7. Under the action of grouting pressure and gravity, the filling material 12 diffuses into the interior of the mining chamber 4. The concave bottom surface of the mining chamber 4 acts as a limiting and gathering surface for the filling material 12. Gas inside the mining chamber 4 is discharged to the surface through the common vent hole 8. When the volume of the injected filling material 12 reaches the calculated main volume, the common vent hole 8 becomes the tail grouting hole for synchronous grouting until the filling material 12 reaches the preset liquid level. Since the filling material 12 fills the mining chamber 4 from front to back, when the filling material 12 rises in the common vent hole 8 at the end of the mining chamber 4 and contacts the liquid level sensor 10 at the preset elevation, it indicates that the entire mining chamber 4 and each grouting hole 7 have reached the preset liquid level. At this time, the injection of filling material 12 is stopped. Figure 3 As shown, during the solidification stage of the filling material 12, the filling material 12 in the mining chamber 4 undergoes volume shrinkage. The liquid column-shaped filling material 12 remaining in the grouting hole 7 and the shared vent hole 8 undergoes downward vertical displacement under the action of gravity, filling the space created by the shrinkage of the roof of the mining chamber 4 and maintaining the contact between the filling material 12 and the roof of the mining chamber 4. At this point, the first mining chamber 4 of the lowest coal bench 9 has been cut, mined, and filled.

[0022] The same cutting, mining, and filling methods as used for the first mining chamber 4 are applied to the other mining chambers 4 of the lowest coal bench 9 until the last mining chamber 4 of the lowest coal bench 9 is cut, mined, and filled. Then, the same cutting, mining, and filling methods as used for the mining chambers 4 on the lowest coal bench 9 are applied to the mining chambers 4 of the next lower coal bench 9 until the last mining chamber 4 of the next upper coal bench 9 is cut, mined, and filled.

[0023] Since there are no horizontal groove-shaped vertical retaining wall holes 6 above the uppermost coal bench 9, meaning there are no directly usable grouting holes 7, before cutting and mining the uppermost coal bench 9, grouting holes 7 are opened in the middle of the horizontal groove-shaped vertical retaining wall holes 6 and the common vent hole 8 in the mining chamber 4 of this layer of mining chamber 4. Then, the uppermost coal bench 9 mining chamber 4 is cut, mined, and filled using the same method as the mining chamber 4 of other layers of coal bench 9.

[0024] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0025] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any minor modifications, equivalent substitutions, and improvements made to the above embodiments based on the technical essence of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for backfilling in multi-stage ascending open-pit mining based on vertical grouting of geotextile retaining walls, characterized in that, Includes the following steps: During the preparation stage of end-side mining, on the flat plate of each coal step (9) above the entrance of the mining chamber (4) and above the designed final mining line of the mining chamber (4), a horizontal groove-shaped vertical retaining wall hole (6) and a common exhaust hole (8) are respectively opened downward to the lowest mining chamber (4). Then, a pluggable fiberglass pipe (5) is inserted into the horizontal groove-shaped vertical retaining wall hole (6). Then, the cutting equipment is used to start cutting and mining at the first mining chamber (4) position of the lowest coal bench (9) until the designed final mining line position is reached and the cutting equipment is withdrawn, at which point a complete mining chamber (4) is formed; the flexible mold bag (1) is lowered into the mining chamber (4) through the horizontal groove-shaped vertical retaining wall hole (6) above the opening of the mining chamber (4), the opening of the flexible mold bag (1) is located on the flat plate of the coal bench (9), and quick-setting filling material is injected into the bag from the opening. After the quick-setting filling material in the flexible mold bag (1) reaches the preset solidification state, the flexible mold bag (1) forms a solid retaining wall (11) and closes the opening of the mining chamber (4); Next, the horizontal groove-shaped vertical retaining wall holes (6) of all coal steps (9) above the first mining chamber (4) are used as grouting holes (7). Filling material (12) is injected into the mining chamber (4) through the grouting holes (7). When the volume of the injected filling material (12) reaches the calculated main volume, the common exhaust hole (8) is turned into the tail grouting hole for synchronous grouting until the filling material (12) reaches the preset liquid level. The same cutting, mining, and filling method as the first mining chamber (4) is used to cut, mine, and fill the other mining chambers (4) of the lowest coal bench (9) until the last mining chamber (4) of the lowest coal bench (9) is cut, mined, and filled. Then, the same cutting, mining, and filling method as the mining chambers (4) on the lowest coal bench (9) is used to cut, mine, and fill the mining chambers (4) of the next lower coal bench (9) until the last mining chamber (4) of the next upper coal bench (9) is cut, mined, and filled. Before cutting and mining the uppermost coal bench (9) in the mining chamber (4), a grouting hole (7) is opened in the middle of the horizontal groove vertical retaining wall hole (6) and the common exhaust hole (8) in the mining chamber (4) of this layer. Then, the uppermost coal bench (9) in the mining chamber (4) is cut, mined and filled using the same method as the mining chamber (4) of other coal benches (9).

2. The method for backfilling in multi-stage upward mining of open-pit mines based on vertical grouting of retaining walls using geotextile bags, as described in claim 1, is characterized in that... The shape and size of the flexible mold bag (1) are adapted to the shape and size of the cross-section of the mining tunnel (4).

3. The method for backfilling in multi-stage upward mining of open-pit mines based on vertical grouting of retaining walls using geotextile bags, as described in claim 1, is characterized in that... The flexible mold bag (1) is provided with a counterweight (2) at the bottom.

4. The method for backfilling in multi-stage upward mining of open-pit mines based on vertical grouting of retaining walls using geotextile bags, as described in claim 1, is characterized in that... A temperature sensor (3) is provided on the side of the flexible mold bag (1) facing the opening of the mining chamber (4).

5. A method for backfilling in multi-stage upward mining of open-pit mines based on vertical grouting using geotextile retaining walls, as described in claim 1, is characterized in that... A liquid level sensor (10) is suspended in the common vent (8).

6. A method for backfilling in multi-stage upward mining of open-pit mines based on vertical grouting using geotextile retaining walls, as described in claim 1, is characterized in that... When the coal step (9) is cut and mined, the fiberglass pipe (5) inserted in the coal step (9) is pulled upward, and the bottom of the fiberglass pipe (5) is higher than the top of the mining chamber (4).

7. A method for backfilling in multi-stage upward mining of open-pit mines based on vertical grouting using geotextile retaining walls, as described in claim 1, is characterized in that... When the cutting equipment cuts and mines the coal bench (9), it cuts the bottom surface of the mining chamber (4) into a concave shape.

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