Treatment method for underground mining mine surface collapse in karst area

Abstract

The invention discloses a treatment method for underground mining mine surface collapse in a karst area, and relates to the technical field of engineering geology and rock mass engineering, and the treatment method comprises the following steps: S100, investigating the geological environment condition of a mining site, and determining the water level, the flow direction and the type of underground water before mining; s200, determining the position and the size of a mining entrance of the mining site; and S300, the mining inlet is blocked, and the blocking height is not lower than the height of the underground water level before mining. According to the treatment method for the underground mining mine surface collapse in the karst area, pollution to underground water can be avoided in the treatment process of the underground mining mine surface collapse in the karst area.

Description

Technical Field

[0001] The present invention relates to the technical fields of engineering geology and rock mass engineering, and particularly to a method for treating ground collapse in underground mining mines in karst areas. Background Art

[0002] The underground environment in karst areas is extremely complex, with a vast cave network and underground river system distributed. And under the influence of karst caves and groundwater flow, karst ground collapse may occur. Due to the particularity of the geological environment in karst areas, when carrying out underground mining operations in this area, especially during the exploration and development of mineral resources, when the roadway mining method is used to develop underground mineral resources, the groundwater must be pumped out to the construction water level before roadway construction. This leads to a drop in the groundwater level, causing an increase in the effective stress in the soil mass and resulting in compression deformation of the soil. Over time, this compression deformation accumulates to a certain extent, triggering the subsidence of the soil mass and ultimately possibly leading to ground collapse.

[0003] Currently, for the treatment of ground collapse in underground mining mines in karst areas, traditional methods mainly include the filling method, grouting method, etc. However, these methods have many drawbacks. For example, the filling method usually uses materials such as sand, gravel, and concrete to fill the collapsed area, which not only consumes a large amount of resources and energy but may also cause pollution to the groundwater environment; although the grouting method can reinforce the stratum to a certain extent, the selection of grouting materials and the control of grouting technology are relatively complex. If the operation is improper, it is easy to cause waste of grouting materials and damage to the surrounding environment.

[0004] In karst areas, the groundwater system is well-developed, and the balance of groundwater is broken during underground mining, further exacerbating the risk of ground collapse. In addition, the karst stratum has strong water permeability, and pollutants in traditional treatment methods are easily infiltrated into the groundwater, causing more serious environmental problems. Therefore, there is an urgent need to design a treatment plan for ground collapse in underground mining mines in karst areas that can avoid polluting the groundwater. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for treating ground collapse in underground mining mines in karst areas to solve the problems existing in the above-mentioned prior art, and to avoid polluting the groundwater during the treatment process of ground collapse in underground mining mines in karst areas.

[0006] To achieve the above purpose, the present invention provides the following scheme:

[0007] The present invention provides a method for treating ground collapse in underground mining mines in karst areas, including the following steps:

[0008] S100, investigate the geological environment conditions of the mining site, and determine the groundwater level, flow direction, and type before mining;

[0009] S200. Determine the location and size of the mining entrance of the mining site;

[0010] S300. Seal the mining entrance, and the sealing height shall not be lower than the groundwater level height before mining.

[0011] After the underground mining operation is completed and the pit is closed, the present invention promptly seals the mining entrance, allowing the groundwater level to recover to the height before mining under natural conditions, ensuring the stability of the soil mass, and thus effectively preventing the occurrence of karst ground collapse; this method can not only be treated at low cost, but also restore the damaged geological environment and avoid polluting the groundwater.

[0012] Preferably, step 100 further includes:

[0013] S110. Determine other groundwater loss gaps near the mining site;

[0014] S120. Seal the other groundwater loss gaps.

[0015] Preferably, it further includes S400. Detect and evaluate the sealed mining entrance to ensure that the strength of the sealing device meets the set requirements and there is no groundwater leakage.

[0016] Preferably, in step S300, the mining entrance is backfilled with crushed stone waste to form a sealing device.

[0017] Preferably, in step S300, a concrete retaining wall is built at the mining entrance to form a sealing device.

[0018] Preferably, in step S300, the mining entrance is backfilled with crushed stone waste and a concrete retaining wall is built to form a sealing device; there is a gap between the crushed stone waste backfill area and the concrete retaining wall.

[0019] Preferably, the drift mining method is adopted for the mining site. Before mining, a vertical shaft is opened at the front end of the mining entrance, and the groundwater in the mining site is pumped out through the vertical shaft until the groundwater level reaches the construction water level. By restoring the original groundwater level, the effective stress of the surface soil mass returns to the mechanical equilibrium state before mining, fundamentally eliminating the soil compression and collapse mechanism caused by the increase in effective stress.

[0020] Preferably, a drift is opened at one end of the mining area of the mining site, the mining entrance is located at the end of the drift far from the mining area, and the sealing device of the mining entrance is arranged in the drift.

[0021] Preferably, the cross-section of the plugging device is the same as the internal cross-section of the roadway, and the plugging device is fixedly sealed with the inner wall of the roadway. The sealing method can be realized by fixing and connecting with concrete for sealing or by setting a sealing layer between the plugging device and the inner wall of the roadway. By precisely controlling the plugging height of the mine entrance, the height of the plugging device is made to exceed the pre-mining groundwater level elevation, transforming the groundwater level restoration mechanism from artificial intervention to natural hydrogeological cycle restoration, and realizing the autonomous rise of the water level by utilizing the natural hydrodynamic conditions in the karst area, reducing a large amount of human and material resources consumption compared with the traditional artificial recharge method; by restoring the original groundwater level, the effective stress of the surface soil returns to the mechanical equilibrium state before mining, fundamentally eliminating the soil compression and collapse mechanism caused by the increase in effective stress.

[0022] Preferably, it further includes S500 to detect the groundwater level of the mining site and ensure that the groundwater level is restored to the pre-mining height.

[0023] The present invention has achieved the following technical effects compared with the prior art:

[0024] After the underground mining operation of the present invention is completed and closed, the mining entrance is promptly plugged, allowing the groundwater level to return to the pre-mining height under natural conditions, ensuring the stability of the soil, and thus effectively preventing the occurrence of karst ground collapse; this method can not only be treated at low cost, but also restore the damaged geological environment and avoid polluting the groundwater. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0026] Figure 1 It is a schematic flow chart of the method for treating ground collapse in underground mines in karst areas in one or some embodiments of the present invention;

[0027] Figure 2 It is a schematic diagram of groundwater drainage before roadway construction in karst areas in Embodiment 1;

[0028] Figure 3 It is a schematic diagram of the groundwater level returning to the pre-mining height after the mining entrance is promptly plugged in Embodiment 1;

[0029] In the figure: 1 - drain pipe, 2 - first karst cave, 3 - second karst cave, 4 - third karst cave, 5 - fourth karst cave, 6 - fifth karst cave, 7 - original groundwater level before mining, 8 - groundwater level after mining, 9 - vertical shaft, 10 - mining area, 11 - backfill with crushed stone waste, 12 - concrete retaining wall, 13 - groundwater level after plugging, 14 - roadway. Detailed implementation manners

[0030] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0031] The purpose of the present invention is to provide a method for treating ground collapse in underground mines in karst areas to solve the problems existing in the above-mentioned prior art. During the treatment of ground collapse in underground mines in karst areas, groundwater pollution can be avoided.

[0032] To make the above objects, features and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific implementation manners.

[0033] For the treatment of ground collapse in underground mines in karst areas, traditional filling methods usually use materials such as sand and gravel, concrete, etc. to fill the collapsed area, which not only consumes a large amount of resources and energy, but also may cause pollution to the groundwater environment; although the grouting method can strengthen the formation to a certain extent, the selection of grouting materials and the control of grouting technology are relatively complex. If the operation is improper, it is easy to cause waste of grouting materials and damage to the surrounding environment. To solve this problem, while preventing ground collapse in underground mines in karst areas, avoiding pollution of groundwater, and simplifying the process steps, the present invention provides a method for treating ground collapse in underground mines in karst areas, as Figure 1 shown, including the following steps:

[0034] S100, investigate the geological environment conditions of the mining site, and determine the groundwater level, flow direction, and type before mining;

[0035] S110, determine other groundwater loss gaps near the mining site;

[0036] S120, plug other groundwater loss gaps. After the groundwater level returns to the height before mining, other groundwater loss gaps can be opened to make the groundwater flow naturally, reducing subsequent manual intervention.

[0037] S200, determine the location and size of the mining entrance of the mining site;

[0038] S300, seal the mining entrance, and the sealing height shall not be lower than the groundwater level before mining.

[0039] S400, detect and evaluate the sealed mining entrance to ensure that the strength of the sealing device meets the set requirements and there is no groundwater leakage;

[0040] S500, detect the groundwater level of the mining site to ensure that the groundwater level is restored to the height before mining.

[0041] There are no restrictions on the structure and material of the sealing device used to seal the mining entrance, as long as the mining entrance can be sealed and no pollution to the groundwater will be caused. In one embodiment, the mining entrance is backfilled with crushed stone waste 11 to form a sealing device. In another embodiment, a concrete retaining wall 12 is built at the mining entrance to form a sealing device.

[0042] To further improve the sealing effect, multiple structures can be used in combination to form multiple sealing devices, thereby improving the sealing effect. In one embodiment, the mining entrance can be backfilled with crushed stone waste 11 and a concrete retaining wall 12 can be built to form a sealing device; there is a gap between the area backfilled with crushed stone waste 11 and the concrete retaining wall 12, thus forming a double-layer sealing structure to improve the sealing effect and prevent groundwater from leaking from the sealed position of the mining entrance.

[0043] In addition to the above solutions, other plugging solutions can also be adopted. Specifically, before the plugging construction, the stability of the roadway is evaluated, and the parts with potential collapse risks are reinforced. During the construction process, closely observe the changes in the surrounding rock of the roadway, and take timely measures to handle any abnormal situations to prevent collapse accidents. During the construction process, effective dust prevention measures should be taken for the dust-generating operation links (such as concrete mixing, drilling construction, etc.), such as setting up dust-proof covers, spraying dust suppression, etc., to reduce dust emissions. Regularly sprinkle water to suppress dust on the construction site and roads to keep the site clean. The wastewater generated during the construction process (such as concrete curing wastewater, grouting wastewater, etc.) should be collected and treated, and only discharged after meeting the discharge standards. Avoid directly discharging wastewater into water bodies such as rivers and lakes to prevent water pollution. The solid waste generated during the construction process (such as waste bricks, concrete blocks, steel bars, etc.) should be classified and collected for treatment. The recyclable waste should be recycled, and the non-recyclable waste should be disposed of at the specified locations and in the specified ways to avoid environmental pollution caused by random disposal. After the plugging is completed, regularly monitor parameters such as gas concentration (such as carbon monoxide, hydrogen sulfide, oxygen, etc.), pressure, water level, and deformation of the plugging structure in the roadway. The monitoring period is determined according to the actual situation, and monitoring instruments and equipment are used for monitoring, such as gas detectors, pressure sensors, water level gauges, total stations, etc. The monitoring data should be recorded and sorted in a timely manner to establish a monitoring file for evaluating and analyzing the plugging effect. According to the monitoring results, timely maintain and repair the plugging device. When cracks, leaks and other problems are found in the plugging device, timely measures should be taken for treatment, such as grouting reinforcement, sealing repair, etc., to ensure the long-term effectiveness and safety of the plugging device.

[0044] The mining site of the present invention adopts the roadway mining method. Before mining, a vertical shaft 9 is opened at the front end of the mining entrance, and the groundwater in the mining site is pumped out through the vertical shaft 9 until the groundwater level reaches the construction water level. One end of the mining area 10 of the mining site is provided with a roadway 14, the mining entrance is located at the end of the roadway 14 far away from the mining area 10, and the blocking device of the mining entrance is arranged in the roadway 14. The cross-section of the blocking device is the same as the internal cross-section of the roadway 14, and the blocking device is fixedly sealed with the inner wall of the roadway 14. The sealing method can be realized by fixed connection and sealing with concrete or by setting a sealing layer between the blocking device and the inner wall of the roadway. By accurately controlling the blocking height of the mine entrance, the height of the blocking device exceeds the pre-mining groundwater level elevation, changing the groundwater level recovery mechanism from manual intervention to natural hydrological cycle repair, and realizing the autonomous rise of the water level by using the natural hydrodynamic conditions in the karst area, reducing a large amount of human and material consumption compared with the traditional artificial recharge method; by restoring the original groundwater level, the effective stress of the surface soil returns to the mechanical equilibrium state before mining, fundamentally eliminating the soil compression and collapse mechanism caused by the increase of effective stress; through the natural hydrological cycle, the self-organization repair of the groundwater system is realized, avoiding the secondary pollution caused by the chemical grouting repair scheme, and ensuring the durability of the treatment effect.

[0045] Embodiment 1

[0046] As Figure 2 and Figure 3 shown, in a certain area, the roadway mining method is adopted for mining operations. As Figure 2 shown, there are multiple karst caves in the mining site. For the convenience of distinction, the multiple karst caves in Figure 2 are respectively named the first karst cave 2, the second karst cave 3, the third karst cave 4, the fourth karst cave 5 and the fifth karst cave 6. During the mining process, usually as Figure 2 shown, the groundwater is pumped and drained to the construction water level. During the pumping and draining process, a drainage pipe 1 is used. One end of the drainage pipe 1 extends into the vertical shaft 9 in front of the roadway 14, and the other end is connected to a water pump on the ground, so as to realize the extraction of groundwater, resulting in the pre-mining original groundwater level 7 in Figure 2 dropping to the post-mining groundwater level 8, making the roadway 14 and the mining area 10 exposed above the groundwater level, which is convenient for mining operations. According to the principle of limited stress, when the groundwater level drops, the effective stress in the soil increases, and the soil compression increases, which in turn leads to soil subsidence. With the accumulation of time, it finally leads to geological environmental disasters such as karst ground collapse.

[0047] In order to avoid geological environmental disasters such as karst ground collapse, the treatment method of this embodiment is as Figure 3 shown. After the mining operation is completed, for Figure 3The mining entrance at the front end of the middle roadway 14 is promptly sealed by methods such as backfilling with crushed stone waste 11 or building a concrete retaining wall 12. The sealing height should exceed the pre-mining groundwater level to prevent further loss of groundwater. Under natural conditions, over time, the groundwater level will continue to recover to Figure 3 the groundwater level 13 after sealing, and the effective stress will also recover to the stable state before mining, effectively controlling situations such as karst ground collapse and achieving the effect of green restoration; Figure 2 and Figure 3 The arrows in respectively show the schematic of the groundwater level decline process during groundwater pumping and the schematic of the groundwater level rise process during groundwater recovery after sealing the mining entrance.

[0048] In the present invention, specific examples are used to elaborate on the principle and implementation manner of the present invention. The description of the above embodiments is only for helping to understand the method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A method for treating ground subsidence in underground mines in karst areas, characterized in that: It includes the following steps: S100. Investigate the geological environment conditions of the mining site, and determine the groundwater level, flow direction and type before mining; S200. Determine the location and size of the mining entrance of the mining site; S300. Seal the mining entrance, and the sealing height shall not be lower than the groundwater level height before mining.

2. The method for controlling ground collapse in underground mines in karst areas according to claim 1, characterized in that: Step 100 further includes: S110. Determine other groundwater loss gaps near the mining site; S120. Seal other groundwater loss gaps.

3. The method for treating ground collapse in underground mines in karst areas according to claim 1, characterized in that: It further includes S400. Detect and evaluate the sealed mining entrance to ensure that the strength of the sealing device meets the set requirements and there is no groundwater leakage.

4. The method for controlling ground collapse in underground mining mines in karst areas according to claim 1, characterized in that: In step S300, the mining entrance is backfilled with crushed stone waste to form a sealing device.

5. The method for treating ground collapse in underground mining mines in karst areas according to claim 1, characterized in that: In step S300, a concrete retaining wall is built at the mining entrance to form a sealing device.

6. The method for treating ground collapse in underground mining mines in karst areas according to claim 1, characterized in that: In step S300, the mining entrance is backfilled with crushed stone waste and a concrete retaining wall is built to form a sealing device; there is a gap between the crushed stone waste backfill area and the concrete retaining wall.

7. The method for controlling ground subsidence in underground mines in karst areas according to claim 1, characterized in that: The drift mining method is adopted for the mining site. Before mining, a vertical shaft is opened at the front end of the mining entrance, and the groundwater in the mining site is pumped out through the vertical shaft until the groundwater level reaches the construction water level.

8. The method for controlling ground collapse in underground mining mines in karst areas according to claim 7, characterized in that: A drift is opened at one end of the mining area of the mining site. The mining entrance is located at the end of the drift far from the mining area, and the sealing device of the mining entrance is arranged in the drift.

9. The method for treating ground subsidence in underground mining mines in karst areas according to claim 8, characterized in that: The cross-section of the sealing device is the same as the inner cross-section of the drift, and the sealing device is fixedly sealed with the inner wall of the drift.

10. The method for controlling ground collapse in underground mines in karst areas according to claim 3, characterized in that: It further includes S500. Detect the groundwater level of the mining site to ensure that the groundwater level is restored to the height before mining.

Images