Flexible layer-by-layer construction method for paste slurry-based filling retaining wall

Abstract

The invention provides a flexible layer-by-layer construction method for a paste slurry-based filling retaining wall, and belongs to the technical field of underground filling mining, and the flexible layer-by-layer construction method for the paste slurry-based filling retaining wall comprises the following steps: S10, when the stoping of an underground stope is about to be finished, planning a filling retaining wall construction position at the stope or a roadway entrance, the section structure parameters of the retaining wall construction position are accurately measured; s20, according to the section structure parameters of the retaining wall construction position, the size of the log, the size of the flexible film bag and the number of layers are designed, and after machining is completed, packaging and transporting are conducted to the position nearby a target stope for storage; s30, after stoping is finished, two sides and a bottom plate of the retaining wall building position are subjected to slag removal, and a flat bottom is formed; paste slurry is adopted as a filling retaining wall building material, paste belongs to mine tailing solid waste recycling materials, the materials are sufficient, and the cost is low; and the paste slurry is directly branched to the retaining wall construction position through the filling pipeline, so that the material transportation cost is saved.

Description

Technical Field

[0001] The present invention relates to the technical field of underground filling mining, and particularly relates to a flexible layer-by-layer construction method for a paste slurry-based filling retaining wall. Background Technique

[0002] The tailings filling mining method has become the mainstream method for underground mining of metal mines due to its characteristics of "treating two harms (goaf and tailings pond) with one waste (tailings)". With the exhaustion of shallow metal resources, the development of deep resources faces major problems such as high stress, high geothermal temperature, high fissure water pressure, and mining disturbance. The paste filling technology, due to its "three non" characteristics of no stratification, no segregation, and no dehydration, provides a reliable solution for the safe, green, and efficient mining of deep metal mines. More and more mines upgrade the traditional high-concentration filling or directly adopt paste filling to achieve the purposes of no dehydration in the stope, high roof contact rate, and strong mechanical properties.

[0003] In mine filling mining, filling retaining walls are often arranged at the stope / roadway exit positions to enclose the goaf, isolate the working area, and bear the pressure of the filling slurry. Its construction technology is a key link to ensure the safe and efficient progress of the filling operation. After years of production practice and innovative research, the filling retaining wall structure and construction methods have developed into types with different functional characteristics.

[0004] In terms of anti-seepage performance, almost all existing filling retaining walls are water-seepage retaining walls. In addition to having the functions of plugging and bearing pressure, they also have a water filtration function to be suitable for the external drainage of the filling slurry dehydration in the stope. Currently, there is no invention of a suitable retaining wall for the paste filling process. By canceling unnecessary water filtration structures, the cost can be reduced, and the integrity and safety of the retaining wall system can be improved.

[0005] In terms of construction materials, the commonly used filling retaining walls mainly include: wooden retaining walls, brick retaining walls, concrete retaining walls, steel structure retaining walls, sandbag retaining walls, etc. The construction of the above retaining walls all involves the problem of transporting materials downward, with a large transportation volume, high cost and high labor intensity. In order to relieve the pressure of underground material transportation, the new retaining wall construction materials adhere to the principle of local material utilization. Patent CN202210441374.1 mentions a filling retaining wall based on an integrated flexible frame and its construction method. Although underground waste rock is directly filled, the waste rock is not conducive to the sealing of the roadway sidewalls, and the connection sealing between the retaining wall and the roadway depends on the accuracy of the 3D printed flexible frame. In addition, this method is only applicable to non-ceiling filling in the upward horizontal layered filling stope and is not applicable to the construction of full-section filling retaining walls. Patent CN201810899117.6 proposes a tailings filling for plugging the mining roadway of the goaf to be filled. A steel structure cofferdam support is erected at the retaining wall construction position, and filling bags are laid inside the support. The stope filling pipe is connected to the filling bags through the filling branch pipe, and the goaf and the filling bags are filled alternately in the same layer to achieve synchronous ceiling of the final retaining wall and the goaf. Although this patent cleverly uses the cemented filling slurry in the stope filling pipe, each layer is composed of multiple rows of filling bags, and the filling branch pipe needs to be continuously switched during filling. At the same time, the grouting operation of the filling bags (goaf) can only be carried out after the filling slurry in the goaf (filling bags) in the previous link has solidified and stood on its own. The labor intensity of the same-layer construction is high, and the cycle of the layer-by-layer alternating operation is long.

[0006] In terms of the cross-sectional shape, the construction forms of retaining walls are mostly straight-wall type (plate-shaped) and right-angle trapezoidal. The plate-shaped retaining wall has poor anti-overturning performance, and the right-angle trapezoidal retaining wall has poor anti-sliding ability. Patent CN201710093444.8 proposed a method for constructing a layered bag-type self-supporting filling retaining wall in a roadway. Similarly, a bag-type retaining wall is constructed using filling slurry, and a stepped dam-building process is adopted. Although the double-sided stepped layered bag-type retaining wall adopted in the present invention has good sealing effect with the roadway sidewall, stable structure and strong anti-sliding ability, the double-sided stepped construction occupies more roadway space. The retaining wall should be set at the entrance of the stope / roadway. Usually, the stope / roadway is connected to the development and mining preparation projects such as sectional roadways. The double-step retaining wall is symmetrically distributed. The stepped shape on the side close to the goaf can maximize the sealing effect, while the stepped shape on the side close to the sectional roadway will cause a significant increase in the roof span of the sectional roadway, which will seriously affect the stability of adjacent mining preparation projects. Patent CN202420630552.X proposed a prefabricated filling retaining wall. The retaining wall is constructed by stepped overlapping masonry of multiple ribbed steel wire gabions fixed to the roadway bolts through ring wall steel bars. The scraper loader loads waste rock into the wire gabion to form a stepped waste rock retaining wall. Although the process of the present invention is simple, the support member of the retaining wall is a ribbed steel wire gabion and cannot be recycled, resulting in high cost. At the same time, the sealing performance between the wire gabion and the sidewall is poor, and it is easy to leak slurry. In addition, due to the limited roadway space, the loading of waste rock requires the assistance of a scraper loader and lifting equipment, resulting in low efficiency and poor safety. Based on this, it is necessary to design a flexible layer-by-layer construction method for paste slurry-based filling retaining walls to solve the defects existing in the prior art. Summary of the Invention

[0007] The present invention provides a flexible layer-by-layer construction method for paste slurry-based filling retaining walls, using paste slurry as the construction material for the filling retaining wall. The paste belongs to the recycled material of mine tailings solid waste, with sufficient materials and low cost. The paste slurry is directly branched to the retaining wall construction position through the filling pipeline, saving the cost of transporting materials downward.

[0008] To solve the above technical problems, the present invention adopts the following technical solutions:

[0009] A flexible layer-by-layer construction method for paste slurry-based filling retaining walls, comprising the following steps:

[0010] S10: When the underground stope mining is about to end, plan the filling retaining wall construction position at the stope or roadway entrance, and accurately measure the cross-sectional structure parameters of the retaining wall construction position;

[0011] S20: According to the cross-sectional structure parameters of the retaining wall construction position, design the dimensions of the log, the dimensions and number of layers of the flexible membrane bag, and after processing, pack and transport them to be stored near the target stope;

[0012] S30: After the stoping is completed, clean the slag and level the floor on both sides and the floor at the position where the retaining wall is to be constructed; and excavate limiting foundation pits at the positions one-third of the distance from the left and right sides of the floor to both sides, and fix the logs to the limiting foundation pits.

[0013] S40: Nest the flexible membrane bags onto the logs successively through the hollow channels in the order of decreasing size, and the logs position the flexible membrane bags.

[0014] S50: Connect the paste from the filling pipeline of the stope being filled to the feeding port of the flexible membrane bag of the first layer through the filling hose, and start filling the paste into the flexible membrane bag of the first layer after opening the valve.

[0015] S60: When the proximal and distal exhaust ports start to return slurry in sequence, it indicates that the flexible membrane bag of the first layer has been filled with feed, and then close the valve of the filling hose.

[0016] S70: Continue to connect the filling hose to the feeding port of the flexible membrane bag of the second layer, and repeat steps S50 - S60 until the flexible membrane bag of the last layer is filled with feed and completely reaches the roof, and the construction of the filling retaining wall is completed.

[0017] Preferably, the planned position for constructing the filling retaining wall in S10 follows the principle of being far from the goaf and having stable surrounding rocks, and the position for constructing the filling retaining wall is arranged at the entrance of the stope or roadway and in a cross-section with stable surrounding rocks.

[0018] Preferably, the flexible membrane bag in S20 is made of a malleable material; the flexible membrane bag is designed in a cubic shape based on the cross-sectional structure parameters of the retaining wall construction position.

[0019] Preferably, the long side of the flexible membrane bag is set perpendicular to the strike of the stope or roadway, and the length of the flexible membrane bag is the width of the stope or roadway; among them, the side far from the goaf during the layout process is the proximal long side, and the side close to the goaf is the distal long side.

[0020] The wide side of the flexible membrane bag is defined along the strike of the stope or roadway, and the width of the flexible membrane bag is 2 - 4 m, and the flexible membrane bags of different layers have different widths; it is stipulated that the width of the flexible membrane bag of the first layer closest to the floor is not less than 3 m and not higher than 4 m, the width of the flexible membrane bag of the last layer closest to the roof is 2 m, and the width of the flexible membrane bags of the middle layers decreases arithmetically according to the number of layers of the flexible membrane bags to 2 m of the flexible membrane bag of the last layer.

[0021] The thickness of the flexible membrane bag is 0.5 m, and the number of required layers of the flexible membrane bag is determined based on the cross-sectional height of the retaining wall construction position.

[0022] Preferably, the flexible membrane bag includes a membrane bag body, a feed inlet arranged at the bottom corner of the side adjacent to the proximal long side of the membrane bag body, a proximal exhaust port and a distal exhaust port arranged on the top surface of the membrane bag, and at least two hollow channels arranged in parallel along the long side inside the membrane bag body;

[0023] The feed inlet is of a concave hole structure, and its aperture is φ50 - 75mm. The feed inlet includes a pipe connection interface arranged on the membrane bag body and an automatic check valve arranged on the pipe connection interface; the pipe connection interface is a quick-insert interface, a threaded interface or a clamp interface, and a sealing compression ring is arranged between the pipe connection interface and the membrane bag body;

[0024] The proximal exhaust port is arranged on the proximal long side of the membrane bag body adjacent to the feed inlet, the distal exhaust port is arranged on the distal long side of the membrane bag body, and the proximal exhaust port and the distal exhaust port are arranged in a diagonal pattern;

[0025] Both the proximal exhaust port and the distal exhaust port are circular patch-type exhaust valves. Both include a base fixed to the membrane bag body by hot pressing and welding, a one-way diaphragm arranged in the inner cavity of the base, a valve cover arranged on the top of the base, exhaust holes arranged on the side wall of the valve cover, and a slurry guiding pipe arranged in the exhaust holes;

[0026] The hollow channels are arranged at a position one-third of the length from the left and right wide sides of the membrane bag body and at a position 1m from the proximal long side of the membrane bag body. The aperture of the hollow channels is 12 - 15cm.

[0027] Preferably, the bottom end of the log in S30 is fixed in a limiting foundation pit on the stope or roadway floor, and the top end is clamped or embedded with the stope or roadway roof. The diameter of the log is 10 - 12cm, the length of the log is 20cm more than the cross-section height at the retaining wall construction position, the aperture of the limiting foundation pit is 10 - 12cm, and the pit depth is 20cm.

[0028] Preferably, S40 positions the flexible membrane bag according to the principle of from large to small and from bottom to top, and nests it layer by layer into the log through the hollow channels. During the process of the flexible membrane bag passing through the log layer by layer, ensure that the exhaust port faces the roof and the feed inlet faces away from the goaf.

[0029] Preferably, the filling hose in S50 is a corrugated hose. The diameter of the filling hose is φ50 - 75mm, which is matched with the specification of the pipe connection interface of the feed inlet. The filling hose is directly connected or connected to the feed inlet of the flexible membrane bag through a drag pump;

[0030] Among them, if the filling paste cannot meet the strength requirements of the filling retaining wall, early-strength agents can be added to improve the strength of the paste-based filling retaining wall. Depending on the mine filling process, the early-strength agent can be directly added during the surface preparation; it can also be uniformly mixed with the paste slurry through a mobile dynamic mixing barrel or a static spiral mixer before filling the paste into the flexible membrane bag underground, and then filled into the flexible membrane bag.

[0031] Preferably, when the proximal and distal exhaust ports of the S60 start to return slurry in chronological order, during the grouting process of the flexible membrane bag, monitor the return slurry sequence of the slurry return pipes at the proximal and distal exhaust ports. When the proximal exhaust port starts to return slurry, it indicates that the flexible membrane bag is about to be filled; when the distal exhaust port then starts to return slurry, it indicates that the flexible membrane bag is filled; if the distal exhaust port returns slurry first, there is a short circuit inside the membrane bag, and it is necessary to check in time and refill.

[0032] Preferably, when filling the paste in the layered flexible membrane bag, there is no need to wait for the previous layer of membrane bag to be cured. After the filling retaining wall is constructed layer by layer, the goaf filling operation can be started immediately without curing.

[0033] The finally constructed filling retaining wall is in a unilateral stepped shape. The side facing the goaf is stepped, and it can form an inlaid structure with the paste in the goaf. The side facing away from the goaf is a straight wall shape.

[0034] From the above technical solutions, it can be seen that the present invention has the following beneficial effects:

[0035] 1. In the present invention, the paste slurry is used as the construction material of the filling retaining wall. The paste belongs to the recycled material of mine tailings solid waste, with sufficient materials and low cost; the paste slurry is directly branched to the retaining wall construction position through the filling pipeline, which can save the cost of transporting materials down.

[0036] 2. In the present invention, a highly ductile flexible membrane bag is used as the construction framework of the filling retaining wall, abandoning the traditional rigid frameworks such as steel structures, wooden structures, and brick structures for retaining wall construction. The construction is simple and fast, and it is beneficial to the sealing of the filling retaining wall with the two sides and the top and bottom sides, and is applicable to various cross-sectional forms such as rectangles and three-centered arches.

[0037] 3. In the present invention, the paste slurry is used as the construction material of the filling retaining wall. The paste has the characteristics of non-bleeding, non-settling, and high strength. The construction of the retaining wall layer by layer and the stope filling can be seamlessly connected. There is no need to wait for the paste to be cured, reducing the curing time after the retaining wall is constructed layer by layer, shortening the mining and filling cycle operation time, and being beneficial to improving the overall mining efficiency of the mine. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a construction step diagram of a method for flexibly constructing a paste slurry-based filling retaining wall provided by the present invention;

[0039] Figure 2Schematic three-dimensional structure diagram of flexible layer-by-layer construction of paste slurry-based filling retaining wall provided by the present invention;

[0040] Figure 3 Front view of the structure of flexible layer-by-layer construction of paste slurry-based filling retaining wall provided by the present invention;

[0041] Figure 4 Left view of the structure of flexible layer-by-layer construction of paste slurry-based filling retaining wall provided by the present invention;

[0042] Figure 5 Top view of the structure of flexible layer-by-layer construction of paste slurry-based filling retaining wall provided by the present invention;

[0043] Figure 6 Schematic overall structure diagram of paste slurry-based flexible membrane bag in the preferred embodiment of the present invention;

[0044] Figure 7 Schematic diagram of the feeding port structure of the paste slurry-based flexible membrane bag in the preferred embodiment of the present invention;

[0045] Figure 8 Schematic diagram of the exhaust port structure of the paste slurry-based flexible membrane bag in the preferred embodiment of the present invention.

[0046] In the figure: 10, flexible membrane bag; 11, membrane bag body; 12, feeding port; 121, pipe connection interface; 122, automatic check valve; 13, proximal exhaust port; 14, distal exhaust port; 15, hollow channel; 20, paste; 30, log; 410, base; 420, one-way diaphragm; 430, valve cover; 440, exhaust hole; 450, slurry guiding pipe. Detailed implementation manners

[0047] The following is a detailed description of a preferred implementation manner of the present invention with reference to the accompanying drawings.

[0048] To achieve the above object, the embodiments of the present invention adopt the following technical solutions: Referring to Figure 1 , a method for flexible layer-by-layer construction of a paste slurry-based filling retaining wall includes the following steps:

[0049] S10: When the underground stope mining is about to end, plan the filling retaining wall construction position at the stope or roadway entrance, and accurately measure the cross-sectional structure parameters of the retaining wall construction position.

[0050] S20: According to the cross-sectional structure parameters of the retaining wall construction position, design the log size, flexible membrane bag size and number of layers, and after processing, pack and transport them to be stored near the target stope.

[0051] S30: After stoping is completed, clean the slag and level the two sides and the floor at the position where the retaining wall is to be constructed; and excavate limiting foundation pits at positions one-third of the distance from the left and right sides of the floor to the two sides, and fix the logs to the limiting foundation pits.

[0052] S40: Nest the flexible membrane bags onto the logs successively through the hollow channels in the order of decreasing size, and the logs will position the flexible membrane bags.

[0053] S50: Connect the paste from the filling pipeline of the stope being filled to the feed inlet of the flexible membrane bag of the first layer through the filling hose, and start filling the paste into the flexible membrane bag of the first layer after opening the valve.

[0054] S60: When the proximal and distal exhaust ports start to return slurry in sequence, it indicates that the flexible membrane bag of the first layer has been filled with feed, and then close the valve of the filling hose.

[0055] S70: Continue to connect the filling hose to the feed inlet of the flexible membrane bag of the second layer, and repeat steps S50 - S60 until the flexible membrane bag of the last layer is filled with feed and completely reaches the roof, and the construction of the filling retaining wall is completed.

[0056] As a preferred technical solution of this embodiment, the planned position for constructing the filling retaining wall in S10 follows the principle of "away from the goaf and with stable surrounding rock", and the position for constructing the filling retaining wall is arranged at the entrance of the stope or roadway and in a cross-section with stable surrounding rock.

[0057] Furthermore, the flexible membrane bag 10 in S20 is made of a malleable material, so that the flexible membrane bag can have good ductility; at the same time, the size and shape of the flexible membrane bag 10 are in the form of a cube, and the size (length × width × thickness) of the flexible membrane bag 10 depends on the cross-section structure parameters of the retaining wall construction position.

[0058] Refer to Figure 2 、 Figure 3 、 Figure 4 、 Figure 5 , in some embodiments, the long side of the flexible membrane bag 10 is set perpendicular to the stope or roadway strike, and the length of the flexible membrane bag 10 is the width of the stope or roadway; among them, the side away from the goaf during the layout process is the proximal long side, and the side close to the goaf is the distal long side;

[0059] The wide side of the flexible membrane bag 10 is defined along the stope or roadway strike, and the width of the flexible membrane bag is 2 - 4 m, and the flexible membrane bags of different layers have different widths; it is stipulated that the width of the flexible membrane bag of the first layer closest to the floor is not less than 3 m and not higher than 4 m, the width of the flexible membrane bag of the last layer closest to the roof is 2 m, and the width of the flexible membrane bags of the middle layers decreases arithmetically according to the number of layers of the flexible membrane bags to 2 m of the flexible membrane bag of the last layer;

[0060] Moreover, the thickness of the flexible membrane bag 10 is 0.5 m, and the number of required layers of the flexible membrane bag 10 is determined based on the sectional height of the retaining wall construction position.

[0061] Furthermore, referring to Figure 2 、 Figure 6 the flexible membrane bag 10 includes a membrane bag body 11, a feed inlet 12, a proximal exhaust port 13, a distal exhaust port 14, and a hollow channel 15. The feed inlet 12 is arranged at the bottom corner of the side adjacent to the proximal long side of the membrane bag body 11. The proximal exhaust port 13 and the distal exhaust port 14 are arranged on the top surface of the membrane bag body 11. The hollow channels 15 are provided with at least two, and the two hollow channels 15 are arranged in parallel along the long side inside the membrane bag body;

[0062] Specifically, referring to Figure 7 the feed inlet 12 is a concave hole structure, and its aperture is φ50 - 75 mm. The feed inlet 12 includes a piping interface 121 arranged on the membrane bag body 11 and an automatic check valve 122 arranged on the piping interface. The piping interface 121 is any form of quick connection interface such as a quick plug interface, a threaded interface, a clamp interface, etc., and a sealing gasket is provided between the piping interface 121 and the membrane bag body 11;

[0063] The proximal exhaust port 13 is arranged on the proximal long side of the membrane bag body 11 adjacent to the feed inlet 12, the distal exhaust port 13 is arranged on the distal long side of the membrane bag body 11, and the proximal exhaust port 13 and the distal exhaust port 13 are arranged in a diagonal pattern;

[0064] Furthermore, referring to Figure 8 the proximal exhaust port 13 and the distal exhaust port 14 are both circular patch type exhaust valves. Both of them include a base 410, a one - way diaphragm 420, a valve cover 430, an exhaust hole 440, and a slurry guiding pipe 450. The base 410 is fixed to the membrane bag body 11 by hot - press welding. The one - way diaphragm 420 is arranged in the inner cavity of the base 410, and a "cross" - shaped or "Y" - shaped slit is formed on the surface of the one - way diaphragm 420. The valve cover 430 is arranged on the top of the base 410. The exhaust hole 440 is arranged on the side wall of the valve cover 430, and the valve cover 430 and the exhaust hole 440 are integrally injection - molded. The slurry guiding pipe 450 is arranged in the exhaust hole 440. It should be noted that the slurry guiding pipe 450 is a transparent small pipe, and the back - slurry state can be clearly monitored;

[0065] Specifically in this embodiment, the number of the hollow channels 15 is two. The hollow channels 15 are used for inserting logs 30 to fix and restrict the sliding of the filling membrane bag. The hollow channels 15 are arranged at the position of one - third of the length of the left - right wide side of the membrane bag body 11 and at the same time at the position 1 m away from the proximal long side of the membrane bag body 11. The aperture of the hollow channels 15 is 12 - 15 cm.

[0066] Further, the bottom end of the log 30 in S30 is fixed in the limiting foundation pit on the stope or roadway floor, and the top end is clamped or embedded with the stope or roadway roof. The diameter of the log 30 is 10 - 12 cm, and the length of the log 30 is 20 cm more than the cross-sectional height at the retaining wall construction position. The aperture of the limiting foundation pit is 10 - 12 cm, and the pit depth is 20 cm.

[0067] Further, in S40, the flexible membrane bag 10 is positioned according to the principle of "from large to small, from bottom to top", and is nested layer by layer through the hollow channels 15 to the log. During the process of the flexible membrane bag 10 passing through the log 30 layer by layer, it is ensured that the exhaust port 440 faces the roof and the feed port 12 faces away from the goaf.

[0068] In some embodiments, the filling hose in S50 is a corrugated hose, which is convenient for moving and connecting to the feed port positions of the flexible membrane bags 10 at different layers. The diameter of the filling hose is φ50 - 75 mm, and it is kept matching with the specification model of the feed port piping interface 121. During use, the grouting method can be selected as pumping or gravity flow according to the pipeline situation, that is, the filling hose is directly or connected to the flexible membrane bag feed port 12 through a drag pump;

[0069] Among them, if the filling paste cannot meet the strength requirements of the filling retaining wall, an early strength agent can be added to improve the strength of the paste slurry-based filling retaining wall. Specifically, depending on the mine filling process, the early strength agent can be directly added during the preparation on the ground; it can also be uniformly mixed with the paste slurry by a mobile dynamic mixing barrel or a static screw mixer before the paste is filled into the flexible membrane bag 10 underground, and then filled into the flexible membrane bag 10.

[0070] Further, when the proximal and distal exhaust ports in S60 start to return slurry in chronological order, during the grouting process of the flexible membrane bag 10, monitor the return slurry sequence of the slurry return pipes at the proximal and distal exhaust ports. When the proximal exhaust port 13 starts to return slurry, it indicates that the flexible membrane bag 10 is about to be filled; when the distal exhaust port 14 then starts to return slurry, it indicates that the flexible membrane bag 10 is filled; if the distal exhaust port 14 returns slurry first, there is a short circuit inside the membrane bag, and it is necessary to check in time and refill.

[0071] Further, when filling the paste into the layered flexible membrane bags 10, there is no need to wait for the previous layer of membrane bags to cure and consolidate, and after the filling retaining walls are constructed layer by layer, the goaf filling operation can be started immediately without curing;

[0072] In this way, the finally constructed filling retaining wall is in a unilateral stepped shape. The side facing the goaf is stepped, and it can form an inlaid structure with the paste in the goaf by mutual coupling. The side facing away from the goaf is in a straight wall shape.

[0073] The following combines a specific embodiment to explain in detail the flexible layer-by-layer construction method of the paste slurry-based filling retaining wall of the present invention.

[0074] A certain nickel mine in Gansu uses the mechanized downward drift cut-and-fill mining method, and the goaf is filled with paste. After the drift stope is mined, a filling retaining wall needs to be built at the intersection of the stope and the sublevel drift. The original filling retaining wall uses a brick masonry structure with the following specifications: the stope span is 5m, the stope height is 4m, and the retaining wall thickness is 0.8m (the brick thickness of the retaining wall is 600mm, and there is a 20mm cement bond between two bricks. The inner and outer surfaces of the retaining wall are sprayed with a layer of not less than 100mm). The shape is a straight wall type, and the straight wall is close to and parallel to the sublevel drift.

[0075] The brick masonry process of the brick retaining wall is as follows: Excavate a 0.2m foundation under the bottom plate of the construction location, lay a metal mesh on the foundation, overlap the inner side of the retaining wall with the drift metal mesh, and extend 1m on the outside. Preset hook bolts at a distance of 1m from the stope floor. After the retaining wall is built, fix the mesh to the retaining wall through the hook bolts, with a bolt spacing of 1m. After the bricklaying of the retaining wall is completed, fix a metal mesh with a grid spacing of 150mm×150mm to the retaining wall using hook bolts and spray mortar, with a spray thickness of 100mm. At the same time, the 2m ore pillar at the connection between the retaining wall and the drift must be sprayed tightly, with a thickness of not less than 100mm, to prevent water seepage and mortar leakage.

[0076] Since the application of the brick retaining wall, it has high strength and good stability. However, the construction materials of the retaining wall are complex, the process is cumbersome, and the labor intensity is relatively large, resulting in a high cost of the brick retaining wall and low construction efficiency. Subsequently, it was optimized to a paste slurry-based filling retaining wall, and an invention of a flexible layer-by-layer construction method for the paste slurry-based filling retaining wall was made. Next, the construction steps will be specifically described with reference to the accompanying drawings:

[0077] When the underground stope mining is about to end, plan the construction location of the filling retaining wall at the stope entrance and accurately measure the cross-sectional structure parameters of the retaining wall construction location;

[0078] According to the cross-sectional structure parameters of the retaining wall construction location, design the log diameter to be 10cm and the length to be 4.2m; the flexible membrane bag has a length of 5m and a thickness of 0.5m. A total of 8 layers of flexible membrane bags are required. The width of the first layer of flexible membrane bag (near the bottom plate) is 4m, and the widths of the flexible membrane bags from the second layer to the seventh layer decrease uniformly layer by layer until the width of the last layer is 2m; the feeding port aperture of the flexible membrane bag is φ50mm, the piping interface is a threaded quick interface, and it is equipped with an automatic check valve; the exhaust port diameter of the flexible membrane bag is φ10mm. From the surface of the flexible membrane bag upwards, there are a base, a one-way diaphragm, a valve cover, an exhaust hole, and a slurry guiding pipe in sequence. The surface of the one-way diaphragm is provided with a "cross"-shaped slit; the hollow structure aperture is 12cm, which are respectively arranged at positions 1.67m and 3.33m away from one wide side of the flexible membrane bag, and at the same time 1m away from the proximal long side of the flexible membrane bag. After the construction materials are processed, they are packed and transported to be stored near the stope;

[0079] After the stope stoping is completed, clean the slag and level the bottom on both sides and the floor at the position where the retaining wall is to be constructed; excavate a limiting foundation pit at a position 1.67 m from the left and right sidewalls of the floor. The aperture of the limiting foundation pit is 10 cm and the depth is 20 cm, and fix the log to the limiting foundation pit.

[0080] Arrange the flexible membrane bags in descending order of size and nest them onto the logs successively through the hollow structure. The logs will position the flexible membrane bags.

[0081] After the flexible membrane bags are laid, connect the paste from the filling pipeline of the stope being filled to the feeding port of the flexible membrane bags on the first layer through a filling hose with a diameter of 50 mm. To ensure the strength of the filling retaining wall, an early-strength agent is added to the paste. After the addition is completed, open the valve to start filling the paste into the flexible membrane bags on the first layer; when the proximal exhaust port and the distal exhaust port start to return slurry in sequence, it indicates that the flexible membrane bags on the first layer have been filled with feed, and then close the valve of the filling hose; continue to connect the filling hose to the feeding port of the flexible membrane bags on the second layer, and directly repeat the above filling steps without waiting for the paste in the flexible membrane bags on the first layer to solidify, until the last layer of flexible membrane bags is filled with feed and completely reaches the top, and the construction of the filling retaining wall is completed. After the construction of the retaining wall is completed, the filling operation can be carried out immediately without waiting for the retaining wall to cure and consolidate.

[0082] The finally constructed filling retaining wall is as shown in the appendix Figure 2 It is a single-sided stepped filling retaining wall. The side facing the goaf is stepped, which can be coupled with the paste in the goaf to form an inlaid structure, which is beneficial to the stability of the retaining wall.

[0083] Good results have been achieved in on-site application. No safety accidents such as paste leakage, retaining wall rupture, and collapse occurred during the filling process in the test stope.

[0084] Compared with the construction of the original brick-filled retaining wall, the construction process of the paste slurry-based filling retaining wall is simple. The construction time can be shortened from 6 h / 4 people to 4 h / 2 people, and the labor intensity is reduced. From the perspective of time, the construction efficiency is increased by at least 33%.

[0085] Compared with the construction of the original brick-filled retaining wall, after the construction of the paste slurry-based filling retaining wall is completed, the stope filling operation can be carried out immediately, canceling the shotcreting and curing link of the brick-filled retaining wall, saving 8 h, reducing the cycle time of the mining and filling operation, and improving the overall stoping efficiency.

[0086] The construction materials for the paste slurry-based filling retaining wall include paste, flexible membrane bags, logs, and early strength agents, while the construction materials for the brick-built retaining wall include fly ash hollow bricks, manufactured sand, cement, wooden boards, and metal meshes. Although the thickness of the retaining wall increases in a stepped manner from 0.8 m to 2 - 4 m, considering that the increased thickness itself requires paste slurry for filling, replacing the hollow bricks with paste as the construction material will not increase the cost due to the increased thickness. The cost of the construction materials for the paste slurry-based filling retaining wall is only the cost of logs, flexible membrane bags, and early strength agents. The cost of the construction materials for the brick-built retaining wall is 1986.1 yuan per unit, and the cost of the construction materials for the paste slurry-based filling retaining wall is 1330 yuan per unit. Compared with the original brick-built filling retaining wall, applying the filling retaining wall of the present invention can save 33% of the material cost.

[0087] The above-described embodiments are merely descriptions of the preferred embodiments of the present invention and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A flexible layer-by-layer construction method for paste slurry-based filling retaining walls, characterized in that, It includes the following steps: S10: When the underground stope mining is about to end, plan the construction position of the filling retaining wall at the stope or roadway entrance, and accurately measure the cross-sectional structure parameters of the retaining wall construction position; S20: According to the cross-sectional structure parameters of the retaining wall construction position, design the dimensions of the log, the dimensions and number of layers of the flexible membrane bag, and after processing, pack and transport them to be stored near the target stope; S30: After the mining ends, clean the slag and level the bottom of the two sides and the floor of the retaining wall construction position; and dig a limiting foundation pit at the position where the floor is one-third away from the two sides on the left and right, and fix the log to the limiting foundation pit; S40: Arrange the flexible membrane bags in the order of decreasing size, and successively nest them onto the log through the hollow channels, and the log positions the flexible membrane bags; S50: Connect the paste from the filling pipeline of the stope being filled to the feed inlet of the flexible membrane bag of the first layer through the filling hose, and start filling the paste into the flexible membrane bag of the first layer after opening the valve; S60: When the proximal and distal exhaust ports start to return slurry in sequence, it indicates that the flexible membrane bag of the first layer has been filled with feed, and then close the valve of the filling hose; S70: Continue to connect the filling hose to the feed inlet of the flexible membrane bag of the second layer, and repeat steps S50 - S60 until the flexible membrane bag of the last layer is filled with feed and completely reaches the roof, and the construction of the filling retaining wall is completed.

2. The flexible layer-by-layer construction method of the paste slurry-based filling retaining wall according to claim 1, characterized in that, The planned construction position of the filling retaining wall in S10 follows the principle of being far away from the goaf and having stable surrounding rock, and the construction position of the filling retaining wall is arranged at the entrance of the stope or roadway and the cross-section with stable surrounding rock.

3. The flexible layer-by-layer construction method of the paste slurry-based filling retaining wall according to claim 1, characterized in that The flexible membrane bag in S20 is prepared from a malleable material; the flexible membrane bag is designed to be a cube shape based on the cross-sectional structure parameters of the retaining wall construction position.

4. The flexible layer-by-layer construction method of the paste slurry-based filling retaining wall according to claim 3, characterized in that, The long side of the flexible membrane bag is set perpendicular to the stope or roadway trend, and the length of the flexible membrane bag is the width of the stope or roadway; among them, the side far away from the goaf during the layout is the proximal long side, and the side close to the goaf is the distal long side; The wide side of the flexible membrane bag is defined along the stope or roadway trend, and the width of the flexible membrane bag is 2 - 4m, and the flexible membrane bags of different layers have different widths; it is stipulated that the width of the flexible membrane bag of the first layer closest to the floor is not less than 3m and not higher than 4m, the width of the flexible membrane bag of the last layer closest to the roof is 2m, and the width of the flexible membrane bags of the middle layers decreases arithmetically according to the number of layers of the flexible membrane bag to 2m of the flexible membrane bag of the last layer; The thickness of the flexible membrane bag is 0.5m, and the number of layers required for the flexible membrane bag is determined based on the cross-sectional height of the retaining wall construction position.

5. The flexible layer-by-layer construction method of the paste slurry-based filling retaining wall according to claim 4, characterized in that The flexible membrane bag includes a membrane bag body, a feed inlet arranged at the bottom corner of the side adjacent to the proximal long side of the membrane bag body, a proximal exhaust port and a distal exhaust port arranged on the top surface of the membrane bag, and at least two hollow channels arranged in parallel along the long side inside the membrane bag body; The feed inlet is a concave hole structure, and its aperture is φ50 - 75mm. The feed inlet includes a pipe connection interface arranged on the membrane bag body and an automatic check valve arranged on the pipe connection interface; the pipe connection interface is a quick-insert interface, a threaded interface or a clamp interface, and a sealing gasket is arranged between the pipe connection interface and the membrane bag body; The proximal exhaust port is arranged on the proximal long side of the membrane bag body adjacent to the feeding port, the distal exhaust port is arranged on the distal long side of the membrane bag body, and the proximal exhaust port and the distal exhaust port are arranged diagonally; Both the proximal exhaust port and the distal exhaust port are circular patch-type exhaust valves, and both include a base fixed to the membrane bag body by hot press welding, a one-way diaphragm arranged in the inner cavity of the base, a valve cover arranged on the top of the base, exhaust holes arranged on the side wall of the valve cover, and a slurry guiding pipe arranged in the exhaust holes; The hollow channel is arranged at a position one-third of the length of the left and right wide sides of the membrane bag body, and at the same time, at a position 1 m away from the proximal long side of the membrane bag body. The aperture of the hollow channel is 12 - 15 cm.

6. The flexible layer-by-layer construction method of the paste slurry-based filling retaining wall according to claim 5, characterized in that, The bottom end of the log in S30 is fixed in the limiting foundation pit on the floor of the stope or roadway, and the top end is clamped or embedded with the roof of the stope or roadway. The diameter of the log is 10 - 12 cm, and the length of the log is 20 cm more than the cross-sectional height at the position where the retaining wall is constructed. The aperture of the limiting foundation pit is 10 - 12 cm, and the depth of the pit is 20 cm.

7. The flexible layer-by-layer construction method of the paste slurry-based filling retaining wall according to claim 6, characterized in that In S40, the flexible membrane bag is positioned according to the principle of from large to small and from bottom to top, and is nested layer by layer through the hollow channel to the log. And during the process of the flexible membrane bag passing through the log layer by layer, it is ensured that the exhaust port faces the roof and the feeding port faces away from the goaf.

8. The flexible layer-by-layer construction method of the paste slurry-based filling retaining wall according to claim 7, characterized in that The filling hose is a corrugated hose, and the diameter of the filling hose is φ50 - 75 mm, which is matched with the pipe connection interface specification of the feeding port. The filling hose is directly connected to the feeding port of the flexible membrane bag or connected through a drag pump; Among them, if the filling paste cannot meet the strength requirements of the filling retaining wall, an early strength agent can be added to improve the strength of the paste slurry-based filling retaining wall. Depending on the mine filling process, the early strength agent can be directly added during the preparation on the ground; it can also be uniformly mixed with the paste slurry by a mobile dynamic mixing barrel or a static screw mixer before filling the paste into the flexible membrane bag underground.

9. The flexible layer-by-layer construction method of the paste slurry-based filling retaining wall according to claim 8, characterized in that, When the proximal and distal exhaust ports in S60 start to return slurry in sequence, during the grouting process of the flexible membrane bag, monitor the sequence of slurry return of the slurry guiding pipes at the proximal and distal exhaust ports. When the proximal exhaust port starts to return slurry, it indicates that the flexible membrane bag is about to be filled; when the distal exhaust port then starts to return slurry, it indicates that the flexible membrane bag is filled; if the distal exhaust port returns slurry first, there is a short circuit inside the membrane bag, and it is necessary to check in time and refill.

10. The method for flexibly constructing the paste slurry-based filling retaining wall layer by layer according to claim 9, characterized in that, When filling the paste in the layered flexible membrane bag, there is no need to wait for the previous layer of membrane bag to be cured. After the filling retaining wall is constructed layer by layer, the goaf filling operation can be started immediately without curing; The finally constructed filling retaining wall is in a unilateral stepped shape. The side facing the goaf is in a stepped shape, which can be coupled with the paste in the goaf to form an inlaid structure, and the side facing away from the goaf is in a straight wall shape.

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