A method for constructing a goaf surrounding rock caving hazard protection system

Abstract

The application relates to a construction method of a goaf surrounding rock collapse hazard protection system and belongs to the technical field of mining. According to geological data and engineering status, parameters are determined, including goaf roof surrounding rock compressive strength sigma c , effective range d of collapse arch bearing horizontal stress, goaf floor buried depth H, thickness h of near-surface weakened rock stratum f , goaf roof rock mass volume weight gamma and goaf surrounding rock lateral pressure coefficient lambda; goaf rock mass critical continuous collapse span L is calculated according to the determined parameters and a goaf rock mass critical continuous collapse span formula cr ; a safety isolation area for isolating and protecting goaf surrounding rock collapse hazards is determined according to an equivalent circle with the goaf rock mass critical continuous collapse span as a diameter; a reinforced concrete sealing wall is used to close the upper opening of the goaf to isolate gas supply, meanwhile, waste rock bulk is used to seal the lower opening of the goaf, so that internal airflow of the goaf is subjected to a flow impact model, and goaf surrounding rock collapse airflow impact hazards are prevented and controlled.

Description

Technical Field

[0001] This invention relates to a method for constructing a protection system for the hazard of rockfall in goaf areas, belonging to the field of mining technology. Background Technology

[0002] As domestic mines gradually move towards deeper mining, under high stress, internal fissures develop in deep ore and rock, causing varying degrees of collapse of the surrounding rock in the goaf. This can easily lead to the collapse of the overlying rock in the goaf and the impact of the collapsing airflow, seriously threatening the safety of personnel and equipment underground.

[0003] During the mining of a certain stage of the stope using the staged drilling and subsequent backfilling method at an iron mine, the roof of the next stage of the goaf suddenly collapsed into the production area due to the impact of production blasting. This created a large, highly unstable goaf, with frequent collapses of the surrounding rock in the early stages, causing the goaf boundary to expand both along the roof and laterally. Although the collapsed rock fragments remain at the bottom of the goaf and can effectively support the surrounding rock below, the resulting hazards of overlying rock subsidence and the impact of the collapsing airflow seriously threaten the safe management of the goaf and the safe mining of the surrounding ore bodies.

[0004] There is currently no specific theory for dealing with the hazards of rockfall in goaf areas. Most scholars often use numerical simulation for prediction and protection. However, due to the complexity of the goaf formation conditions and engineering geological conditions, the numerical model differs from the actual working conditions, and it is difficult to accurately predict the impact range of rockfall and collapse airflow in goaf areas. Summary of the Invention

[0005] This invention addresses the complexities of goaf formation conditions and engineering geological conditions, the discrepancy between numerical models and actual working conditions, and the difficulty in accurately predicting the impact range of goaf surrounding rock collapse and caving airflow. It proposes a method for constructing a goaf surrounding rock caving hazard protection system. This invention utilizes safety isolation zones, reinforced concrete sealing walls, and waste rock piles to achieve isolation and protection against goaf surrounding rock collapse hazards and containment protection against caving airflow hazards, thereby ensuring the inherent safety of goaf remediation and the safe mining of surrounding ore bodies.

[0006] A method for constructing a hazard prevention system for rockfall in a goaf includes setting up a safety isolation zone, reinforced concrete walls, and a waste rock pile. The specific steps are as follows: (1) Parameter determination: The parameters involved in the critical continuous caving span of the goaf rock mass include the compressive strength of the surrounding rock of the goaf roof. s c Unit weight of the roof rock mass in the goaf c Effective range of horizontal stress borne by the caving arch d , depth of the bottom plate of the goaf H Thickness of near-surface weakened rock layer h fand the lateral pressure coefficient of the surrounding rock in the goaf l , where the parameters s c and c Parameters obtained from rock physics and mechanics experiments d Select parameters based on the scale of cavitation in the empty area. H , h f and l Based on the current status of the project and geological data; (2) Calculate the critical continuous caving span of the goaf rock mass based on the parameters determined in step (1) and the formula for the critical continuous caving span of the goaf rock mass. L cr Using the critical continuous collapse span of the goaf rock mass as the diameter, a safety isolation zone for isolating and protecting against the risk of goaf rock collapse is defined by equivalent circles. (3) Use reinforced concrete sealing walls to seal the upper opening of the goaf to isolate the gas supply, and use waste rock piles to seal the lower opening of the goaf so that the airflow inside the goaf follows the flow impact model, in order to prevent the impact of the airflow from the collapse of the surrounding rock in the goaf.

[0007] The safety isolation zone is defined according to the critical continuous collapse span of the goaf rock mass. This is because when the goaf boundary expands within the safety isolation zone, the surrounding rock of the goaf will form a relatively stable natural equilibrium arch after a certain degree of collapse. When the goaf boundary expands beyond the safety isolation zone, the surrounding rock of the goaf will enter a continuous collapse stage and has the potential to cause a large collapse and penetrate to the surface. Therefore, the safety protection of the surface and underground should be considered in conjunction. By dynamically monitoring the distance between the goaf boundary and the safety isolation zone, the hazards of goaf rock collapse can be effectively isolated and protected, and the safe mining of the surrounding ore body can also be guaranteed.

[0008] The formula for the critical continuous caving span of the goaf rock mass in step (2) is as follows: ; In the formula, L cr This refers to the critical span of continuous collapse of the rock mass in the goaf. s c For the compressive strength of the surrounding rock of the roof of the void, d The effective range of horizontal stress borne by the caving arch. H For the depth of the bottom plate of the goaf, h f To weaken the thickness of near-surface rock layers, c For the unit weight of the roof rock mass in the goaf, l This represents the lateral pressure coefficient of the surrounding rock in the goaf.

[0009] The reinforced concrete sealing wall is located outside the safety isolation zone and at the junction of the bottom ore extraction structure and the goaf in the upper-middle section.

[0010] Preferably, observation doors are installed on the reinforced concrete sealing wall to observe the distance between the boundary of the goaf and the safety isolation zone.

[0011] The waste rock pile should be kept at a safe distance from the open area to reduce the impact speed of the falling airflow and avoid the impact hazards of the falling airflow on underground personnel; The geometry of the collapsed rock blocks in the goaf is simplified to an ellipsoid, and the distance between the waste rock pile and the goaf entrance in step (3) is a safe distance. x l The safe distance is determined according to safety regulations that stipulate that the wind speed that the human body can withstand should not exceed 12 m / s. Therefore, the safe distance... x l satisfy ; In the formula, x l This refers to the distance between the waste rock pile and the entrance to the goaf. v This refers to the horizontal airflow velocity when a rock fragment hits the ground. l Let be the perimeter of the horizontal projected area of ​​the collapsed rock block in the void. a The semi-major axis of the caving rock block in the void area of ​​the ellipsoid. b It is the short semi-axis of the rock block that collapsed in the empty area of ​​the ellipsoid.

[0012] The method for determining the location of the waste rock bulk pile is as follows: Based on the center of the equivalent circle of the lower segment of the goaf, with a safe distance x l A safety distance auxiliary circle is drawn with a diameter of 100 mm. The waste rock pile is set at the intersection of the safety distance auxiliary circle and the mining preparation project.

[0013] Preferably, the waste rock pile is located in a preparatory roadway connected to the goaf, and its cross-sectional shape along the axis of the preparatory roadway is an isosceles trapezoid.

[0014] The beneficial effects of this invention are: (1) The present invention includes the setting of a safety isolation zone, a reinforced concrete sealing wall and a waste rock pile. The safety isolation zone is an equivalent circle with the critical continuous collapse span of the goaf rock mass as its diameter. The reinforced concrete sealing wall and the waste rock pile are set according to the flow impact model. The former is used to seal the upper opening of the goaf to isolate gas supply, and the latter is used to seal the lower opening of the goaf. (2) The construction method of the goaf surrounding rock collapse protection system of the present invention provides an economical and practical protection system for the treatment of goaf surrounding rock collapse hazards by setting up a safety isolation zone to isolate and protect the overlying surrounding rock collapse hazards, and then using reinforced concrete sealing walls to seal the upper opening of the goaf to isolate gas supply and waste rock piles to seal the lower opening to prevent the impact hazards of collapse airflow. Attached Figure Description

[0015] Figure 1 This is a schematic diagram showing the location of the lower segmented horizontal safety isolation zone and the waste rock pile in Example 1; Figure 2 This is a schematic diagram showing the location of the segmented horizontal safety isolation zone and the reinforced concrete wall in Example 1; Figure 3 for Figure 1 A schematic diagram of the waste rock pile along the tunnel axis; Figure 4 for Figure 2 A schematic diagram of the cross section of a reinforced concrete wall; Figure 5 This is a schematic diagram showing the location of the segmented horizontal safety isolation zone and the waste rock pile in Example 2; Figure 6 This is a schematic diagram showing the location of the segmented horizontal safety isolation zone and the reinforced concrete wall in Example 2. Detailed Implementation

[0016] The present invention will be further described in detail below with reference to specific embodiments, but the scope of protection of the present invention is not limited to the content described.

[0017] The present invention discloses a method for constructing a protection system for the collapse hazards of surrounding rock in goaf areas, which mainly includes the setting up of a safety isolation zone, a reinforced concrete sealing wall, and a waste rock pile: the safety isolation zone is an equivalent circle with the critical continuous collapse span of the goaf rock mass as its diameter, used to isolate and protect against the collapse hazards of the overlying surrounding rock in the goaf; the reinforced concrete sealing wall and the waste rock pile are set up according to the flow impact model, the former is used to seal the upper opening of the goaf to isolate gas supply, and the latter is used to seal the lower opening of the goaf to prevent and control the impact hazards of the airflow from the collapse of the surrounding rock in the goaf; The specific steps are as follows: (1) Parameter determination: The parameters involved in the critical continuous caving span of the goaf rock mass include the compressive strength of the surrounding rock of the goaf roof. s c Unit weight of the roof rock mass in the goaf c Effective range of horizontal stress borne by the caving arch d , depth of the bottom plate of the goaf H Thickness of near-surface weakened rock layer h fand the lateral pressure coefficient of the surrounding rock in the goaf l , where the parameters s c and c Parameters obtained from rock physics and mechanics experiments d Select parameters based on the scale of cavitation in the empty area. H , h f and l Based on the current status of the project and geological data; (2) Calculate the critical continuous caving span of the goaf rock mass based on the parameters determined in step (1) and the formula for the critical continuous caving span of the goaf rock mass. L cr Using the critical continuous collapse span of the goaf rock mass as the diameter, a safety isolation zone for isolating and protecting against the risk of goaf rock collapse is defined by equivalent circles. The safety isolation zone is delineated according to the critical continuous collapse span of the goaf rock mass. This is because when the goaf boundary expands within the safety isolation zone, the surrounding rock of the goaf will form a relatively stable natural equilibrium arch after a certain degree of collapse. When the goaf boundary expands beyond the safety isolation zone, the surrounding rock of the goaf will enter a continuous collapse stage, and there is a possibility of a large collapse that breaks through to the surface. Therefore, the safety protection of the surface and underground should be considered in conjunction. By dynamically monitoring the distance between the goaf boundary and the safety isolation zone, the hazards of goaf rock collapse can be effectively isolated and protected, and the safe mining of the surrounding ore body can also be guaranteed. The formula for the critical continuous collapse span of rock mass in the goaf is: ; In the formula, L cr This refers to the critical span of continuous collapse of the rock mass in the goaf. s c For the compressive strength of the surrounding rock of the roof of the void, d The effective range of horizontal stress borne by the caving arch. H For the depth of the bottom plate of the goaf, h f To weaken the thickness of near-surface rock layers, c For the unit weight of the roof rock mass in the goaf, l The coefficient of lateral pressure of the surrounding rock in the goaf; (3) The upper opening of the goaf is sealed by reinforced concrete sealing wall to isolate the gas supply. At the same time, the lower opening of the goaf is sealed by waste rock pile, so that the airflow inside the goaf follows the flow impact model to prevent the impact of the airflow from the surrounding rock of the goaf. Specifically, the reinforced concrete sealing wall is set outside the safety isolation zone and at the bottom of the upper and middle section where the ore extraction structure connects with the goaf. An observation door is set on the reinforced concrete sealing wall to observe the distance between the boundary of the goaf and the safety isolation zone. The waste rock pile is kept at a safe distance from the goaf entrance to reduce the impact speed of the caving airflow and avoid the impact hazards to underground personnel. The geometry of the caving rock block in the goaf is simplified to an ellipsoid. The distance between the waste rock pile and the goaf entrance in step (3) is the safe distance. x l The safe distance is determined according to safety regulations that stipulate that the wind speed that the human body can withstand should not exceed 12 m / s. Therefore, the safe distance... x l satisfy ; In the formula, x l This refers to the distance between the waste rock pile and the entrance to the goaf. v This refers to the horizontal airflow velocity when a rock fragment hits the ground. l Let be the perimeter of the horizontal projected area of ​​the collapsed rock block in the void. a The semi-major axis of the caving rock block in the void area of ​​the ellipsoid. b For the minor semi-axis of the rock block that collapsed from the empty area of ​​the ellipsoid; Based on the center of the equivalent circle of the lower segment of the goaf, with a safe distance x l A safety distance auxiliary circle is drawn with a diameter of 100 mm. The waste rock pile is set at the intersection of the safety distance auxiliary circle and the mining preparation project. Preferably, the waste rock stockpile is located in the preparatory roadway connected to the goaf, and the cross-sectional shape along the axis of the preparatory roadway is an isosceles trapezoid.

[0018] Example 1: A method for constructing a protection system for rockfall hazards in goaf areas (see Example 2) Figure 1~4 The system includes a safety isolation zone 2, a reinforced concrete wall 8, and a waste rock pile 5. The safety isolation zone 2 is set according to the critical continuous collapse span of the goaf rock mass, and the reinforced concrete wall 8 and the waste rock pile 5 are set according to the flow impact model.

[0019] Safety isolation zone 2 is designed to isolate and protect against the hazards of rock collapse in the goaf, while ensuring the safe mining of the surrounding ore body 3. Reinforced concrete sealing wall 8 is designed to seal the upper opening of the goaf to isolate gas supply, and waste rock pile 5 is designed to seal the lower opening of the goaf. The combined action of reinforced concrete sealing wall 8 and waste rock pile 5 can make the airflow inside the goaf conform to the flow impact model, thereby preventing the impact hazards of airflow from rock collapse in the goaf. The specific steps are as follows: (1) Parameter determination: The parameters involved in the critical continuous caving span of the goaf rock mass include the compressive strength of the surrounding rock of the goaf roof. s c Unit weight of the roof rock mass in the goaf c Effective range of horizontal stress borne by the caving arch d, depth of the bottom plate of the goaf H Thickness of near-surface weakened rock layer h f and the lateral pressure coefficient of the surrounding rock in the goaf l , where the parameters s c and c Parameters obtained from rock physics and mechanics experiments d Select parameters based on the scale of cavitation in the empty area. H , h f and l Based on the current status of the project and geological data; (2) Calculate the critical continuous caving span of the goaf rock mass based on the parameters determined in step (1) and the formula for the critical continuous caving span of the goaf rock mass. L cr Using the critical continuous collapse span of the goaf rock mass as the diameter, a safety isolation zone for isolating and protecting against the risk of goaf rock collapse is defined by equivalent circles. The safety isolation zone is delineated according to the critical continuous collapse span of the goaf rock mass. This is because when the goaf boundary expands within the safety isolation zone, the surrounding rock of the goaf will form a relatively stable natural equilibrium arch after a certain degree of collapse. When the goaf boundary expands beyond the safety isolation zone, the surrounding rock of the goaf will enter a continuous collapse stage, and there is a possibility of a large collapse that breaks through to the surface. Therefore, the safety protection of the surface and underground should be considered in conjunction. By dynamically monitoring the distance between the goaf boundary and the safety isolation zone, the hazards of goaf rock collapse can be effectively isolated and protected, and the safe mining of the surrounding ore body can also be guaranteed. like Figure 1 and Figure 2 As shown, safety isolation zone 2 is based on the critical continuous collapse span of the goaf rock mass. L cr The equivalent circle with diameter; The formula for the critical continuous collapse span of rock mass in the goaf is: ; In the formula, L cr This refers to the critical span of continuous collapse of the rock mass in the goaf. s c For the compressive strength of the surrounding rock of the roof of the void, d The effective range of horizontal stress borne by the caving arch. H For the depth of the bottom plate of the goaf, h f To weaken the thickness of near-surface rock layers, c For the unit weight of the roof rock mass in the goaf, l The coefficient of lateral pressure of the surrounding rock in the goaf; like Figure 1 and Figure 2As shown, the location of safety isolation zone 2 is based on the shape of the horizontal voids in each segment. In Example 1, it is assumed that the void is a regular ellipsoid. Therefore, the center of safety isolation zone 2 coincides with the center of the lower segment horizontal void section 1 and the upper segment horizontal void section 7, and its diameter is the critical continuous collapse span of the goaf rock mass. L cr At this point, upper and lower segmented horizontal safety isolation zones 2 can be set; (3) Use reinforced concrete sealing wall 8 to seal the upper opening of the goaf to isolate the gas supply, and use waste rock pile 5 to seal the lower opening of the goaf so that the airflow inside the goaf follows the flow impact model to prevent the impact of the airflow from the collapse of the surrounding rock in the goaf. Specifically, the reinforced concrete sealing wall is located outside the safety isolation zone, at the junction of the bottom ore-producing structure in the upper-middle section and the preparatory roadway of the goaf. Observation doors are installed on the reinforced concrete sealing wall to observe the distance between the goaf boundary and the safety isolation zone; such as Figure 2 As shown, the reinforced concrete sealing wall 8 is set at the upper section level to seal the upper opening of the goaf to isolate gas supply; in order to ensure the service life and construction safety of the reinforced concrete sealing wall 8, the reinforced concrete sealing wall 8 is set outside the safety isolation zone 2, and is set at the connection between the bottom ore extraction structure 9 of the upper and middle section and the mining preparation roadway of the goaf 7. A schematic diagram of the cross-section of the reinforced concrete wall is shown below. Figure 4 The reinforced concrete wall 8 is set in the preparatory roadway connected to the goaf and is used to seal the gas supply to the upper goaf opening; the steel bars 15 can increase the strength and deformation resistance of the sealing wall; the anchor bolts 16 are used to fix the reinforced concrete wall 8 to the two sides and the roof of the roadway section 14; a certain size observation door 17 is left on the reinforced concrete wall 8, mainly for the safe personnel to enter and exit underground, and to facilitate the observation of the goaf collapse boundary; The waste rock pile 5 is kept at a safe distance from the open area to reduce the impact speed of the falling airflow and avoid the impact hazards of the falling airflow on the personnel underground; like Figure 1 As shown, the waste rock pile 5 is set at the lower section level and should maintain a certain safe distance from the opening of the empty area to reduce the impact speed of the falling airflow. The geometry of the collapsed rock blocks in the goaf is simplified to an ellipsoid. In step (3), the distance between the waste rock pile and the entrance to the goaf is a safe distance. x l The safe distance is determined according to safety regulations that stipulate that the wind speed that the human body can withstand should not exceed 12 m / s. Therefore, the safe distance... x l satisfy ; In the formula, x lThis refers to the distance between the waste rock pile and the entrance to the goaf. v This refers to the horizontal airflow velocity when a rock fragment hits the ground. l Let be the perimeter of the horizontal projected area of ​​the collapsed rock block in the void. a The semi-major axis of the caving rock block in the void area of ​​the ellipsoid. b For the minor semi-axis of the rock block that collapsed from the empty area of ​​the ellipsoid; Based on the center of the horizontal open section 1 of the lower segment, with a distance greater than or equal to the safety distance x l The distance is the diameter, and a safety distance auxiliary circle 4 is drawn. The waste rock pile 5 is set at the intersection of the safety distance auxiliary circle 4 and the lower segment mining preparation project 6. A schematic diagram of the waste rock pile along the tunnel axis is shown below. Figure 3 The waste rock pile 5 can be located near the source of waste rock, preferably in a preparatory roadway connected to the goaf, and its cross-sectional shape along the axis of the preparatory roadway is an isosceles trapezoid. The main parameters of the waste rock pile include the length of the upper plane 11, the length of the lower plane 12, and the size of the waste rock blocks on the airflow impact surface 13. Preferably, the length of the upper plane 11 is 2.0m, the length of the lower plane 12 should not be less than 6.0m, and the size of the waste rock blocks on the airflow impact surface 13 should not be less than 0.2m, so as to increase the pile's resistance to airflow impact.

[0020] Example 2: The following describes in detail the construction method of the goaf surrounding rock collapse hazard protection system in Example 2, based on an actual iron mine project. The specific steps are as follows: When a certain iron mine was using the segmented rock drilling stage stope and subsequent backfilling method to mine a certain stage of the stope, the roof of the next stage of the goaf suddenly broke through to the production area due to the production blasting, forming a large and highly unstable goaf. Moreover, the surrounding rock collapsed very frequently in the early stage of formation. The resulting overlying rock collapse hazard and the impact hazard of the collapse airflow seriously threatened the safe management of the goaf and the safe mining of the surrounding ore bodies. Compressive strength of surrounding rock in the vacant area s c and density c The rock physical mechanics experiments determined the strength to be 26.97 MPa and 2.71 t / m, respectively. 3 The effective range of horizontal stress borne by the caving arch d Generally, empirical values ​​are used. In the early stages of the formation of this void, caving activity is intense, and at this time, the parameters... d A depth of 2.6 m can be taken; based on the current engineering status and geological data, the burial depth of the goaf floor can be obtained. H and the thickness of near-surface weakened rock layers h f The heights are 363.6m and 35m respectively; during the continuous caving stage, the rock blocks mainly caved under their own weight, experiencing relatively little lateral pressure. l A value of 0.1 can be used. Substitute the above parameters into the equation. Seeking L cr =126.5259m; Considering that the overlying rock mass of the collapsed void has been subjected to the effects of open-pit mining and underground mining for a long period of time, its strength should be weakened. The above estimate is a conservative estimate. Finally, 130m can be taken as the estimated value of the critical continuous collapse span. In actual engineering projects, the shape of the empty area is often irregular. In this case, the method of equivalent circle is needed to delineate the safety isolation zone 2. Specifically, the location of safety isolation zone 2 should be referenced to the outline of the horizontal open area section of each segment, such as... Figure 5 As shown, based on the outline 18 of the lower segment horizontal void section, an equivalent circle 1 is drawn for the lower segment horizontal void section. The center of the equivalent circle 1 is taken as the center of the safety isolation zone 2. Then, with the critical continuous collapse span of the rock mass (130m) as the diameter, the safety isolation zone of the lower segment horizontal section can be obtained. Figure 6 As shown, draw the equivalent circle 7 of the upper segment horizontal void section according to the outline line 19 of the upper segment horizontal void section. Take the center of the equivalent circle 7 of the upper segment horizontal void section as the center of the safety isolation zone 2. Then, take the critical continuous collapse span of the rock mass (130m) as the diameter to obtain the safety isolation zone of the upper segment horizontal section. like Figure 5 As shown, the waste rock pile 5 is set at the lower section level and should maintain a certain safe distance from the opening of the empty area to reduce the impact speed of the falling airflow. The area of ​​collapsed rock blocks in the vacant area is difficult to measure. Based on engineering experience, the horizontal projection shape of the rock blocks corresponding to a batch of collapsed rock blocks in the vacant area can be taken as 24m in length and 15m in width. At this time, the geometry of the collapsed rock blocks in the vacant area is simplified to an ellipsoid. Then, the semi-major axis of the collapsed rock blocks in the ellipsoid is... a =12m, the minor semi-axis of the rock mass that collapsed in the void of the ellipsoid. b =5m, the perimeter of the horizontal projected area of ​​the corresponding collapsed rock block in the void. ; Actual measured horizontal impact airflow velocity when the fallen rock blocks landed v The value is 30.95 m / s; therefore, from It can be determined that the distance between the waste rock pile and the entrance to the goaf is... x l ≥ 9.64m; Depend on Figure 5 As shown, based on the center of the lower segment horizontal void section 1, a safety distance auxiliary circle 4 is drawn with a diameter greater than or equal to 9.64m. The waste rock pile 5 is set at the intersection of the safety distance auxiliary circle 4 and the mining preparation project 6. Depend on Figure 6As shown, the reinforced concrete wall 8 is set in the preparation roadway connected to the goaf to seal the gas supply to the upper goaf opening. At the same time, it should be set outside the safety isolation zone 2 as much as possible to ensure the safety of the reinforced concrete wall 8. The installation of the reinforced concrete sealing wall and waste rock pile in Example 2 is basically the same as in Example 1. It should be noted that all access points of the preparatory engineering connected to the void should be sealed, including access points that are already connected and access points that may be connected as the surrounding rock of the void collapses. The reinforced concrete sealing wall 8 and waste rock pile 5 preferred in Example 1 can be applied to Example 2.

[0021] The specific embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A method for constructing a protection system for rockfall hazards in goaf areas, characterized in that: The specific steps for setting up a safety isolation zone, reinforced concrete sealing wall, and waste rock pile are as follows: (1) Parameter determination: The compressive strength σ of the surrounding rock of the roof of the void area is determined based on geological data and the current engineering status. c d, effective range of horizontal stress borne by the collapsed arch, H, depth of the bottom plate of the goaf, and thickness of the near-surface weakened rock layer. f γ, the unit weight of the roof rock mass in the goaf and the lateral pressure coefficient of the surrounding rock in the goaf; (2) Calculate the critical continuous caving span L of the goaf rock mass based on the parameters determined in step (1) and the formula for the critical continuous caving span of the goaf rock mass. cr Using the critical continuous collapse span of the goaf rock mass as its diameter, a safety isolation zone for isolating and protecting against the risk of surrounding rock collapse in the goaf is defined by equivalent circles; the formula for the critical continuous collapse span of the goaf rock mass is: ； In the formula, L cr σ represents the critical span of continuous collapse of the rock mass in the goaf. c d is the compressive strength of the surrounding rock of the goaf roof, d is the effective range of the horizontal stress borne by the caving arch, H is the burial depth of the goaf floor, and h is the compressive strength of the surrounding rock of the goaf roof. f γ represents the thickness of the near-surface weakened rock layer, γ represents the unit weight of the roof rock mass in the goaf, and λ represents the lateral pressure coefficient of the surrounding rock in the goaf. (3) The upper opening of the goaf is sealed with a reinforced concrete sealing wall to isolate the gas supply, and the lower opening of the goaf is sealed with a waste rock pile to make the airflow inside the goaf follow the flow-around impact model in order to prevent the impact hazards of the airflow from the collapsing surrounding rock in the goaf; the geometry of the collapsing rock block in the goaf is simplified to an ellipsoid, and the distance between the waste rock pile and the opening of the goaf is the safety distance x. l Safe distance x l satisfy ； In the formula, x l denoted as , where is the distance from the waste rock pile to the opening of the goaf; v is the horizontal impact airflow velocity when the collapsed rock blocks land; l is the perimeter of the horizontal projected area of ​​the collapsed rock blocks in the goaf; a is the major semi-axis of the collapsed rock blocks in the ellipsoidal goaf; and b is the minor semi-axis of the collapsed rock blocks in the ellipsoidal goaf.

2. The method for constructing the goaf surrounding rock collapse hazard protection system according to claim 1, characterized in that: The reinforced concrete sealing wall is located outside the safety isolation zone and at the connection point between the bottom ore extraction structure of the upper and middle section and the preparatory roadway of the goaf.

3. The method for constructing the goaf surrounding rock collapse hazard protection system according to claim 1, characterized in that: The method for determining the location of waste rock bulk stockpiles is as follows: Based on the center of the equivalent circle of the lower segment of the goaf, with a safety distance x l A safety distance auxiliary circle is drawn with a diameter of 100 mm. The waste rock pile is set at the intersection of the safety distance auxiliary circle and the mining preparation project.

4. The method for constructing the goaf surrounding rock collapse hazard protection system according to claim 3, characterized in that: The waste rock pile is located in the preparatory roadway connected to the goaf, and its cross-sectional shape along the axis of the preparatory roadway is an isosceles trapezoid.

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