A method for filling of end-slope mining chamber based on bulk pressing pre-stressed top joint

Abstract

The application discloses a kind of based on bulk body pushing prestressed end help mining chamber filling method, including bulk body broken material filling, setting gravity pile, filling paste filling layer, pushing machine heap loading, chamber wall protection, chamber mouth closure, supplementary support and the like steps.The present application does not need to construct fixed facilities, with the advantages of flexible deployment, low investment cost, etc., while effectively solving the problem that loose material cannot support roof, suitable for short service life, slope overburden resource limited open pit end temporary mining operation;The unique design of gravity pile can enhance the stability of gravity pile, increase the friction at the bottom, prevent gravity pile from slipping or overturning;Artificial segmentation is carried out on the mining chamber, blocking the flow of bulk body broken material in the filling process towards the chamber mouth direction;It is convenient for prestressed segment loading;Provide a relatively closed space for the action of paste filling layer;Bulk body broken material filling layer can not only make up the settlement deformation, but also provide supplementary support force, while not increasing filling cost too much.

Description

Technical Field

[0001] This invention relates to a method for filling end-side mining tunnels, specifically a method for filling end-side mining tunnels based on granular prestressed jacking. Background Technology

[0002] Statistics show that my country's open-pit coal mines have billions of tons of resources covered by slope embankments. The application of end-face mining technology makes it possible to recover these resources. When using end-face mining machines or end-face adit mining techniques, a series of continuous adits will form at the lower part of the mined end-face slope. These adits must be backfilled in a timely manner to ensure slope stability. Currently, the mainstream and mature technology for backfilling such adits in the industry is paste backfilling technology. This technology involves preparing a paste from raw materials such as gangue, cement, and fly ash at a fixed ground backfilling station, and then pumping it to the working face for backfilling. This method produces high-strength backfill, but it suffers from problems such as long construction period, large infrastructure investment, long solidification time, and slow effectiveness. It is not suitable for backfilling "short-frequency, fast-paced" open-pit mine end-face slopes with short service life and limited slope resources. Summary of the Invention

[0003] To address the problems existing in the prior art, this invention provides a method for filling end-slope mining tunnels based on granular push-prestressed top connection, which requires less investment, can be deployed quickly, and can rapidly generate supporting force to provide effective support for the top of the mining tunnel.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a method for filling end-slope mining tunnels based on granular prestressed jacking, comprising the following steps: A mobile rock dumping machine is used to fill the mining tunnel in sections from the inside out. After the first section of loose material is filled, the first limiting groove is dug at the bottom of the mining tunnel, and then the first set of gravity piles is placed in the first limiting groove. The outer part of the gravity pile is a guide baffle plate with a right-angled trapezoidal cross-section, and the inner part is a pile heel plate with a rectangular cross-section. The inner and outer sides of the guide baffle plate are respectively the crushed stone blocking surface and the guide slope surface. The gravity pile is integrally formed, and the height of the guide baffle plate is 2 / 3 of the height of the mining tunnel. After the first set of gravity piles is placed, the mobile rock dumper continues to fill the loose material until the loose material slides down the guide slope. At this time, the pusher is used to push the loose material into the mine along the guide slope until the pressure stabilizes and remains at the design value for a predetermined time. Then, a mobile dumping machine is used to continue filling the second section outside the first gravity pile. The second section of filling is divided into three layers. The lower layer is filled with loose material with a thickness of 1 / 2 of the mining height. The middle layer is filled with expanding material as a paste filling layer. The upper surface of the paste filling layer is flush with the upper surface of the guide baffle plate. The upper layer is filled with loose material until it reaches the top. After the second section is filled, the second limiting groove is dug at the bottom of the mining chamber, and the second set of gravity piles is placed in the second limiting groove. After the second set of gravity piles is placed, the mobile rock dumper continues to fill the loose material until the loose material slides down the guide slope. At this time, the pusher is used again to push the loose material into the mining chamber along the guide slope until the pressure stabilizes and remains at the design value for a predetermined time. Then, a mobile dumping machine is used to continue filling the third section outside the second gravity pile, and so on, until the filling reaches the entrance of the mining tunnel, after which the entrance is sealed.

[0005] Furthermore, the gravity pile is a monolithically cast concrete body with internal steel reinforcement; the pile heel plate is 1-2m long, the pile heel plate height is not less than 1 / 4 of the height of the guide baffle plate, and the guide slope angle is less than the internal friction angle of the filling loose material.

[0006] Furthermore, each group of gravity piles consists of multiple gravity piles arranged side by side, with the two outermost gravity piles being 0.25m away from the sidewall of the mining chamber. The spacing between two adjacent groups of gravity piles must ensure that, even after the thrust applied by the last group of gravity piles has been attenuated, the expansion force of the loose material at the location of the previous group of gravity piles still meets the prestressing required to support the top of the mining chamber.

[0007] Furthermore, the method of sealing the tunnel entrance is divided into two types: For open-pit mines that can discharge internally, filling is stopped after reaching the entrance of the pit, and the entrance is sealed by internal discharge. For open-pit mines that cannot discharge internally, closed gravity piles are used to seal the entrance.

[0008] Furthermore, the closed gravity pile has the same structural shape as the gravity pile but different dimensions. The height of the closed gravity pile is 0.3m lower than the height of the mining tunnel. The length of the pile heel plate of the closed gravity pile is 3 / 5-4 / 5 of the height of the mining tunnel. The guide slope of the closed gravity pile is parallel to the slope of the open-pit mine end slope.

[0009] Furthermore, the filling bulk material includes hard aggregate and soft soil. The hard aggregate is selected from sandstone, conglomerate or limestone from the overburden of open-pit mines, and the soft soil is clay or loess from the overburden. The ratio of hard aggregate to soft soil is 7:3.

[0010] Furthermore, the limiting groove extends laterally through the entire mining tunnel, with a depth of 1 / 2 to 2 / 3 of the pile heel plate height, and the limiting groove is inclined at 15° with the outer side higher than the inner side.

[0011] Furthermore, adjacent sets of gravity piles are connected by steel chains.

[0012] Furthermore, before each mining chamber is filled with loose materials, anchor cables are first installed in the supporting coal pillars on both sides of the mining chamber and the two anchor cables are connected by steel cables. If there is a mining chamber that has already been filled next to the mining chamber to be filled, then anchor cables that run through the entire supporting coal pillar are installed on the shared supporting coal pillar.

[0013] Furthermore, grouting holes are drilled from the step platform above the mining tunnel to the top of the mining tunnel, and then expanding filling liquid is injected into the grouting holes to form a supplementary layer.

[0014] Compared with the prior art, the present invention has the following advantages: It requires no fixed facilities, has advantages such as flexible deployment and low investment cost, and effectively solves the problem that loose materials cannot support the roof. It is suitable for temporary mining operations at the end of open-pit mines with short service life and limited slope overburden resources.

[0015] Using crushed stone from open-pit mines as the main backfill material is effective, low-cost, readily available, and convenient for construction. The equipment used is also existing equipment in the mine, so there are no additional costs.

[0016] The unique design of gravity piles enhances their stability, increases bottom friction, and prevents slippage or overturning. Artificial segmentation of the mining tunnel prevents the flow of loose materials towards the tunnel entrance during filling; facilitates the gradual application of prestress; and provides a relatively enclosed space for the paste filling layer to function effectively.

[0017] Paste filling layers can not only compensate for the settlement and deformation of loose materials, but also provide additional support, without significantly increasing filling costs.

[0018] The stacking of the pusher is simple to implement, and when combined with vibration, it can effectively provide support for the top plate.

[0019] The tunnel wall protection is simple to operate, avoids crushing damage, and the bending of the steel cables later can indirectly support the top, achieving a dual function.

[0020] The sealing of the mining chamber achieves self-stabilization, maintaining the expansion force of the filling material and ensuring support for the top of the mining chamber. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the bulk material filling method of the present invention; Figure 2 This is a schematic diagram of the gravity pile and limiting groove structure of the present invention; Figure 3 This is a schematic diagram showing the positional relationship between two adjacent sets of gravity piles and the internal cross-section after the mining tunnel is filled. Figure 4 This is a schematic diagram showing the positional relationship of the paste filling layers in this invention; Figure 5This is a schematic diagram of the tunnel wall protection structure of the present invention; Figure 6 This is a schematic diagram of the structure for sealing the entrance of the grout using gravity piles according to the present invention; Figure 7 This is a schematic diagram of the grouting hole and supplementary layer structure of the present invention; In the diagram: 1-End wall; 2-Mining chamber; 3-Mobile rock dumper; 4-Mobile belt conveyor; 5-Mobile crusher; 6-Single-bucket truck; 7-Gravity pile; 700-Guiding baffle plate; 701-Guiding slope; 702-Stone blocking surface; 703-Pile heel plate; 704-Steel chain; 8-Limiting groove; 9-Paste filling layer; 10-Supplementary layer; 11-Supporting coal pillar; 12-Anchor cable tie rod; 13-Steel cable; 14-Closed gravity pile; 15-Grouting hole. Detailed Implementation

[0022] The invention will now be further described with reference to the accompanying drawings.

[0023] 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.

[0024] This invention provides a technical solution, comprising the following steps: like Figures 1 to 7 As shown, after the mining chamber 2 of the end face 1 is mined out, a mobile rock dumper 3 is used to fill the mining chamber 2 in sections from the inside out. The mobile rock dumper 3 is connected to a mobile belt conveyor 4. The other end of the mobile belt conveyor 4 is located outside the opening of the chamber and is connected to a mobile crusher 5. A single-bucket truck 6 transports the usable material stripped from the open-pit mine working face to the mobile crusher 5. The crushed material is transported to the mobile rock dumper 3 via the mobile belt conveyor 4 and finally filled into the interior of the mining chamber 2. The mobile rock dumper 3 and the mobile belt conveyor 4 travel in reverse.

[0025] The filling bulk materials include hard aggregate and soft soil. The hard aggregate is selected from medium-coarse sandstone, conglomerate, or hard limestone from the overburden of open-pit mines. This type of rock has high uniaxial compressive strength and the blocks formed after crushing have sharp edges and corners. Under the high-stress pushing action of the subsequent press, it can form a stable internal friction angle and interlocking structure, producing a significant shear expansion effect to support the roof. The soft soil is soft clay or loess from the overburden. The ratio of hard aggregate to soft soil is 7:3. Hard aggregate accounts for the majority to build a rigid load-bearing skeleton so that the fine powder after crushing can fill the pores between the skeletons, forming a "dense skeleton type" bulk structure. Soft soil accounts for the minority. During the pressing process, soft soil is used to fill the gaps in the hard aggregate and plays a certain role in cementation.

[0026] like Figures 2 to 4 As shown, after the first section of loose material is filled, the first limiting groove 8 is excavated at the bottom of the mining tunnel 2, and then the first set of gravity piles 7 are placed in the first limiting groove 8.

[0027] The outer part of the gravity pile 7 is a guide baffle plate 700 with a right-angled trapezoidal cross-section, and the inner part is a pile heel plate 703 with a rectangular cross-section. The inner and outer sides of the guide baffle plate 700 are respectively a crushed stone blocking surface 703 and a guide slope surface 701. Under the action of the pusher, the guide slope surface 701 can guide the filling material to move upward, thereby generating an upward supporting force to support the top plate of the mining chamber 2. The pile heel plate 703 generates an anti-overturning moment through its own weight and the weight of the crushed material filling above, which enhances the stability of the gravity pile 7, increases the bottom friction, and prevents the gravity pile 7 from slipping or overturning.

[0028] The gravity pile 7 is a monolithically cast concrete body with internal steel reinforcement; the pile heel plate 703 is 1-2m long and its height is not less than 1 / 4 of the height of the guide baffle plate 700. The angle of the guide slope 701 is less than the internal friction angle of the filling loose material. The height of the guide baffle plate 700 is 2 / 3 of the height of the mining tunnel 2 to prevent the filling loose material from sliding down from above after the pusher is withdrawn, thus ensuring the effective transmission of thrust.

[0029] Each group of gravity piles 7 consists of multiple gravity piles 7 arranged side by side. The distance between the sides of the two outer gravity piles 7 and the sidewall of the mining chamber 2 is 0.25m, which prevents rigid scraping and jamming with the sidewalls during installation. It also facilitates the discharge of air from the filling bulk materials.

[0030] The limiting groove 8 extends horizontally through the entire mining chamber 2, with a depth of 1 / 2 to 2 / 3 of the height of the pile heel plate 703. In order to better block loose materials and prevent the gravity piles 7 from overturning, the limiting groove 8 is inclined at 15° with the outer side higher than the inner side. The distance between two adjacent sets of gravity piles 7 must be such that after the thrust applied by the last set of gravity piles 7 has been attenuated, it can still ensure that the expansion force of loose materials at the position of the previous set of gravity piles 7 meets the prestressing support for the top of the mining chamber 2.

[0031] After the first set of gravity piles 7 are placed, the movable rock dumper 3 continues to fill the loose material until the loose material slides down the guide slope 701. At this time, the pusher is used to push the loose material into the mining chamber 2 along the guide slope 701. While maintaining a high-strength static thrust, vibration is applied in addition. The vibration wave induces the liquefaction of the loose particles, reduces the relative motion resistance between particles, and makes the filling material exhibit fluid-like fluidity, thereby improving the degree of deep densification and ensuring that the filling material in the entire segment can achieve a good high-prestressed roof connection effect.

[0032] During this process, the thrust value is monitored in real time. The thrust design value is determined based on the "roof-coal pillar": the vertical expansion force caused by the thrust must be greater than or equal to the self-weight load of the overlying strata at the current segment. The thrust value obtained from the pressure sensor is compared with the design value in real time to make the actual thrust value approach and eventually stabilize at the design target value. After the pressure remains stable for a predetermined time (e.g., 3-5 minutes), it is determined that the filling body of this segment has reached the prestressed roof connection standard.

[0033] Then, the movable rock dumping machine 3 continues to fill the second section outside the first gravity pile 7. The second section of filling is divided into three layers. The lower layer is filled with loose debris with a thickness of 1 / 2 of the height of the mining chamber 2. The middle layer is filled with expanding material as a paste filling layer 9. The upper surface of the paste filling layer 9 is flush with the upper surface of the guide baffle plate 700. The upper layer is filled with loose debris until it reaches the top. The middle paste filling layer 9 will continue to expand. After the loose debris has filled this section, the expansion space of the paste can make up for the settlement deformation of the loose debris due to gravity. It can also make up for the supporting force of the filling loose debris on the top of the mining chamber 2. Due to the arrangement of the gravity pile 7, a relatively closed segmented space is provided for the paste filling layer 9, which can effectively play the supplementary role of the paste filling layer 9.

[0034] After the second section of filling is completed, the second limiting groove 8 is excavated at the bottom of the mining chamber 2, and the second set of gravity piles 7 are placed in the second limiting groove 8. After the second set of gravity piles 7 are placed, the mobile rock dumping machine 3 continues to fill the loose material until the loose material slides down the guide slope 701. At this time, the pusher is used again to push the loose material into the mining chamber 2 along the guide slope 701 until the pressure stabilizes and maintains the design value for a predetermined time. Then, the mobile rock dumping machine 3 continues to fill the third section outside the second gravity piles 7, and so on, until the opening of the mining chamber 2 is filled and then the opening is sealed.

[0035] like Figure 3 , Figure 6 As shown, as needed, connecting steel chains 704 can be installed between two adjacent sets of gravity piles 7 to enhance the anti-tipping and anti-slip function of the gravity piles 7. For open-pit mines that can be internally discharged, filling is stopped after filling to the entrance of the pit, and the entrance is sealed by internal discharge. For open-pit mines that cannot be internally discharged, sealing gravity piles 14 are used to seal the entrance. The sealing gravity piles 14 have the same structural shape as the gravity piles 7 but different dimensions. The height of the sealing gravity piles 14 is 0.3m lower than the height of the pit 2. The length of the pile heel plate of the sealing gravity piles 14 is 3 / 5-4 / 5 of the height of the pit 2. The guide slope of the sealing gravity piles 14 is parallel to the slope of the end slope of the open-pit mine. This ensures that the sealing gravity piles 14 completely block the bulk materials filling the pit 2, maintain the expansion force of the bulk materials, and ensure support for the top of the pit 2.

[0036] like Figure 5 As shown, the vertical expansion force generated by the compressed bulk material supports the mining chamber 2, but the horizontal expansion force can cause crushing damage to the walls on both sides of the chamber 2. Therefore, the walls need to be protected. Before filling each mining chamber 2 with bulk material, anchor cables 12 are installed in the supporting coal pillars 11 on both sides of the chamber 2 and connected by steel cables 13. If there is a previously filled mining chamber 2 next to the one to be filled, anchor cables 12 that run through the entire supporting coal pillar 11 are installed on the shared supporting coal pillar 11. The subsequent settlement and deformation of the filled bulk material under the influence of gravity will cause the steel cables 13 to bend, which in turn pulls the two sides of the chamber to move towards each other. The resulting compressive force will act on the filled bulk material, thus maintaining the support force on the top and achieving a dual effect.

[0037] like Figure 7As shown, after the mine shaft is sealed, supplementary support is implemented for mine shafts where internal drainage and covering have not been achieved or where the process takes a long time. Grouting holes 15 are drilled from the platform above mine shaft 2 to the top of mine shaft 2. Then, expanding filling fluid is injected into mine shaft 2 through the grouting holes 15 or the gaps on the upper surface of the sealed gravity piles 14, forming a supplementary layer 10. After the filling fluid solidifies and expands, it not only fills the gaps between the gravel but, more importantly, forms an expanding filling layer at the top. The resulting expansion force supplements the gravel filling support force, thus providing supplementary support.

[0038] 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.

[0039] 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 filling the end slope mining chamber based on the bulk pressing pre-stressed joint, characterized in that, Includes the following steps: Using a mobile rock dumping machine (3), the mining chamber (2) is filled in sections from the inside out. After the first section of loose material is filled, the first limiting groove (8) is dug at the bottom of the mining chamber (2), and then the first set of gravity piles (7) is placed in the first limiting groove (8). The outer part of the gravity pile (7) is a guide baffle plate (700) with a right trapezoidal cross section, and the inner part is a pile heel plate (703) with a rectangular cross section. The inner and outer sides of the guide baffle plate (700) are the gravel blocking surface (703) and the guide slope surface (701), respectively. The gravity pile (7) is integrally formed, and the height of the guide baffle plate (700) is 2 / 3 of the height of the mining tunnel (2). After the first set of gravity piles (7) are placed, the mobile dumping machine (3) is used to fill the loose material until the loose material slides down from the guide slope (701). At this time, the pusher is used to push the loose material into the mining chamber (2) along the guide slope (701) until the pressure stabilizes and remains at the design value for a predetermined time. Then, a mobile dumping machine (3) is used to continue filling the second section outside the first gravity pile (7). The second section of filling is divided into three layers. The lower layer is filled with loose material with a thickness of 1 / 2 of the height of the mining chamber (2). The middle layer is filled with expanding material as a paste filling layer (9). The upper surface of the paste filling layer (9) is flush with the upper surface of the guide baffle plate (700). The upper layer is filled with loose material until it reaches the top. After the second section of filling is completed, the second limiting groove (8) is dug at the bottom of the mining chamber (2), and the second set of gravity piles (7) is placed in the second limiting groove (8). After the second set of gravity piles (7) is placed, the movable rock dumping machine (3) is used to fill the loose material until the loose material slides down from the guide slope (701). At this time, the pusher is used again to push the loose material into the mining chamber (2) along the guide slope (701) until the pressure stabilizes and remains at the design value for a predetermined time. Then, a mobile dumping machine (3) is used to continue filling the third section outside the second gravity pile (7), and so on, until the filling reaches the opening of the mining chamber (2) and the opening is sealed.

2. The method for filling end-slope mining tunnels based on granular prestressed jacking according to claim 1, characterized in that, The gravity pile (7) is a monolithically cast concrete body with steel bars inside; the pile heel plate (703) is 1-2m long, the height of the pile heel plate (703) is not less than 1 / 4 of the height of the guide flow plate (700), and the angle of the guide slope (701) is less than the internal friction angle of the filling loose material.

3. The method for filling end-slope mining tunnels based on granular prestressed jacking according to claim 1, characterized in that, Each group of gravity piles (7) consists of multiple gravity piles (7) arranged side by side. The distance between the side of the two outer gravity piles (7) and the side wall of the mining chamber (2) is 0.25m. The spacing between two adjacent groups of gravity piles (7) must ensure that after the thrust applied by the last group of gravity piles (7) is attenuated, the expansion force of the loose material at the position of the previous group of gravity piles (7) can still meet the prestress of the support for the top of the mining chamber (2).

4. The method for filling end-slope mining tunnels based on granular prestressed jacking according to claim 1, characterized in that, The methods for sealing the tunnel entrance are of two types: For open-pit mines that can discharge internally, filling is stopped after reaching the entrance of the pit, and the entrance is sealed by covering it with internal discharge. For open-pit mines that cannot discharge internally, closed gravity piles (14) are used to seal the entrance.

5. A method for filling end-slope mining tunnels based on granular prestressed jacking according to claim 4, characterized in that, The closed gravity pile (14) has the same structural shape as the gravity pile (7) but different dimensions. The height of the closed gravity pile (14) is 0.3m lower than the height of the mining tunnel (2). The length of the pile heel plate of the closed gravity pile (14) is 3 / 5-4 / 5 of the height of the mining tunnel (2). The guide slope of the closed gravity pile (14) is parallel to the slope of the open-pit mine end slope.

6. The method for filling end-slope mining tunnels based on granular prestressed jacking according to claim 1, characterized in that, The filling bulk material includes hard aggregate and soft soil. The hard aggregate is selected from sandstone, conglomerate or limestone from the overburden of open-pit mines, and the soft soil is clay or loess from the overburden. The ratio of hard aggregate to soft soil is 7:

3.

7. The method for filling end-slope mining tunnels based on granular prestressed jacking according to claim 1, characterized in that, The limiting groove (8) extends horizontally through the entire mining tunnel (2), with a depth of 1 / 2 to 2 / 3 of the height of the pile heel plate (703). The limiting groove (8) is inclined at 15° with the outer side higher than the inner side.

8. The method for filling end-slope mining tunnels based on granular prestressed jacking according to claim 1, characterized in that, The two adjacent sets of gravity piles (7) are connected by steel chains (704).

9. A method for filling end-slope mining tunnels based on granular prestressed jacking according to claim 1, characterized in that, Before filling each mining chamber (2) with loose materials, anchor rods (12) are arranged in the supporting coal pillars (11) on both sides of the mining chamber (2) and the two anchor rods (12) are connected by steel cables (13). If there is a mining chamber (2) that has been filled next to the mining chamber (2) to be filled, anchor rods (12) that run through the entire supporting coal pillar (11) are arranged on the shared supporting coal pillar (11).

10. A method for filling end-slope mining tunnels based on granular prestressed jacking according to claim 1, characterized in that, Drill grouting holes (15) from the step platform above the mining chamber (2) to the top of the mining chamber (2), and then inject expansion filling liquid into the grouting holes (15) to form a supplementary layer (10).

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