Double-layer charge structure and roof breaking method for roof breaking by pulling well based on VCR blasting

Abstract

The application discloses a double-layer charging structure for pulling a well and breaking a roof based on VCR blasting, which is characterized by sequentially arranging a hole bottom fixing block, a hole bottom filling section, a first explosive layer, a spacing layer, a second explosive layer and a hole mouth filling section from bottom to top in a reserved roof layer blast hole, arranging explosive amounts of the explosive layers in a manner of less at bottom and more at top, spacing the layers with granular matter, plugging the hole bottom and the hole mouth with the granular matter, arranging digital electronic detonators at the bottom layer of the explosive layers, and connecting the digital electronic detonators with a blasting main bus through a detonator foot wire to form an initiation network; the application also discloses a roof breaking method, which is characterized by arranging the double-layer charging structure in all blast holes, and setting an initiation sequence as an initiation interval of 25 ms between the same layer sections, and a delay initiation interval of no less than 75 ms between the layers, and has the characteristics of a reserved rock body height of 6.5-8.0 m, high operation safety, reduced overall charging amount, reduced cost and high blasting success rate, and effectively solves the problem of the contradiction between the reserved height and the blasting success rate during roof breaking operation.

Description

Technical Field

[0001] This invention belongs to the field of mining preparation engineering technology, and specifically relates to a double-layer charging structure for shaft roof breaking based on VCR blasting, and a method for breaking the roof using the double-layer charging structure. Background Technology

[0002] The commonly used well-forming method for underground mining and tunneling is VCR blasting, which employs a bottom-up, layer-by-layer blasting approach. A single blast raises the well to a height of approximately 2.3 meters. When blasting near the roof, manual loading and breaking of explosives are required. To ensure the safety of blasting personnel, a certain height of rock slab is usually reserved for concentrated blasting, i.e., roof breaking. It is generally considered that a safe height of 5.0 meters is the critical value for roof breaking. However, when the blasting height is 5.0 meters or higher, the success rate is often less than 50%, easily leading to roof breaking failure. This results in difficulties in confirming the condition of the remaining rock slab, unclear blast fractures, unknown residual height, and the risk of sudden collapse of remaining rock slabs during processing, creating localized vacuum suction and posing a risk of falls from height. This significantly increases safety hazards for personnel and equipment when handling roof breaking failures. Therefore, if... Figure 1 As shown, existing roof-breaking charge structures and methods based on VCR blasting typically involve: reserving a safety height threshold (around 5.1m) for the roof-breaking borehole; employing a single-layer charge structure (i.e., cement blocks at the bottom of the hole filled with sand to a thickness of 0.7m, continuous explosive filling in the middle section, and sealing the borehole opening with 2.0~2.5m of sand); and using digital electronic detonators and a detonating cord initiation network for detonation. The blasting sequence follows a 50ms interval between detonator initiation intervals for roof-breaking blasting operations. While this method can improve the blasting success rate to some extent, the high explosive energy and the requirement for a large borehole sealing length, coupled with the thick rock strata and significant clamping effect, result in a still low blasting success rate, failing to effectively address the aforementioned risk of blasting failure. In addition, in actual use, compared with the risk of handling blasting failure, some mining areas will choose to set the reserved height lower than the critical value of the safety height, such as setting the reserved height to 4.5m or even lower, in order to improve the success rate of breaking through the roof. However, if the reserved height is lower than the critical value of the safety height, there will inevitably be new safety hazards such as insufficient reserved height leading to the collapse of the reserved rock slab.

[0003] Therefore, the research topic of this application is to determine which roof-breaking charge structure and method can simultaneously satisfy the requirements of sufficient reserved height and high blasting success rate. Summary of the Invention

[0004] To address the contradiction between the reserved height and the blasting success rate when using traditional charging structures and methods for roof breaking operations in VCR blasting well pulling, this invention proposes a double-layer charging structure for roof breaking in VCR blasting, and a roof breaking method using this double-layer charging structure. This can increase the reserved height for roof breaking to 6.5-8.0m, while simultaneously increasing the blasting success rate to nearly 100%, effectively resolving the contradiction between reserved height and blasting success rate. This enables roof breaking operations with high safety and low cost.

[0005] This invention is achieved through the following technical solution:

[0006] This invention proposes a double-layer charge structure for well top breaking based on VCR blasting. Within a pre-reserved blast hole in the top layer, from bottom to top, a bottom fixing block, a bottom filling section, a first explosive layer, a spacer layer, a second explosive layer, and a borehole filling section are sequentially arranged. The bottom filling section, spacer layer, and borehole filling section are filled with particulate matter. The first and second explosive layers are filled with emulsion explosives. Digital electronic detonators are deployed at the bottom of the first and second explosive layers, and these detonators are connected to the blasting busbar via lead wires to form a detonation network.

[0007] By adopting the above technical solution, through a double-layered charging structure, the explosives are loaded in layers through spacers filled with granular material. Digital electronic detonators are used for layered blasting. On the one hand, this can effectively avoid the problem of failure to break through the roof due to excessively thick pre-reserved rock slabs and excessive rock layer clamping effect, thereby improving the success rate of blasting. On the other hand, it allows the thickness of the pre-reserved roof layer to be increased to 6.5~8.0m, effectively avoiding operational risks during the charging process. In addition, the detonation connection can be achieved through the blasting busbar, saving detonating cord and effectively reducing the cost of roof breaking operations.

[0008] Furthermore, the size of the hole bottom fixing block matches the inner diameter of the borehole, and the hole bottom fixing block is provided with a lifting ring for hoisting and fixing.

[0009] Furthermore, the size of the hole bottom fixing block matches the inner diameter of the blast hole in the top plate layer, and the hole bottom fixing block is provided with a lifting ring for hoisting and fixing, so as to reduce the difficulty of construction.

[0010] Furthermore, the height of the bottom filling section and the spacer layer is 0.7~1.1m, and the height of the orifice filling section is 1.5~1.9m. The heights of the bottom filling section, the spacer layer, and the orifice filling section are all designed based on the reserved top plate layer borehole height and the charge amount. The heights of the bottom filling section and the orifice filling section are determined based on the principle of avoiding the blasting energy from dissipating along the borehole axis, and the height of the spacer layer is determined based on the principle of avoiding the first explosive layer from directly detonating the second explosive layer.

[0011] Furthermore, the orifice filling section includes a particulate filling section and a liquid filling section. The particulate filling section has a height of not less than 0.5m, and the liquid filling section is filled with a sealed water column bag with a height of not less than 1.0m. When the second explosive layer is detonated, the liquid inside the water column bag enters the particulate filling section. On the one hand, this effectively reduces the dust generated by the blast, achieving a wet blasting effect. On the other hand, it cools and lubricates the particulate filling section, preventing the high-temperature sintering of the internal particulates from causing the blasting energy to not be fully applied to the blasting area, thus leading to the failure of the rock mass blasting corresponding to the orifice filling section.

[0012] Furthermore, the filling height of the first explosive layer is less than that of the second explosive layer, effectively utilizing the free surface below the top plate layer, reducing the amount of explosive while ensuring the blasting height, thus saving costs.

[0013] Furthermore, the filling height of the first explosive layer is half the filling height of the second explosive layer, effectively solving the problem of the large clamping effect of the upper rock mass on the roof, and achieving successful blasting with the minimum amount of explosives.

[0014] The present invention also proposes a method for well-pulling and roof-breaking based on VCR blasting, wherein a double-layer charge structure of any of the above-mentioned types is uniformly distributed in the blast holes arranged around the well-pulling central axis on the reserved roof layer.

[0015] Furthermore, the aforementioned method for breaking through the ceiling includes the following steps:

[0016] S1: With the shaft axis as the center point, several blasting circles with different radii are set up. Several blast holes are evenly arranged on the blasting circles. The spacing between the blast holes is designed based on the principle of interaction of blasting energy. The number of blasting circles is determined according to the shaft radius and the spacing between the blast holes. Explosives are filled into the blast holes and blasting is carried out layer by layer from bottom to top until the remaining rock mass thickness is 6.5~8.0m.

[0017] S2: Use wires or other ropes to lower the hole bottom fixing block from the top to the bottom of the blast hole in the remaining rock mass to block the bottom of the blast hole, fill the granular material to the set height, and form the hole bottom filling section;

[0018] S3: Tie a single digital electronic detonator to a strip of emulsion explosive as the detonating warhead, and lower it to the top of the bottom filling section of the hole. Continue to lower the remaining emulsion explosives without digital electronic detonators until the first explosive layer is filled to the designed filling height.

[0019] S4: Fill the first explosive layer with particulate matter to the designed height of the spacer layer;

[0020] S5: Fill the second explosive layer using the method in step S3 until the designed filling height of the second explosive layer is reached. The filling height of the second explosive layer is greater than the filling height of the first explosive layer.

[0021] S6: Fill the second explosive layer with particulate matter to the preset height within the orifice filling section;

[0022] S7: Repeat steps S2-S6 to complete the layout of all blast holes in S1. Evenly connect all digital electronic detonator leads to the blasting busbar to form a detonation network. The detonator segment setting method of the detonation network is as follows: the detonation interval of digital electronic detonators in the same explosive layer is 25ms. After the first explosive layer in all blast holes is detonated, the second explosive layer is detonated. The interval between the last detonation of the first explosive layer and the first detonation of the second explosive layer is not less than 75ms.

[0023] S8: After clearing the area and securing all safety exits, detonate within the specified detonation time to carry out the roof breaching operation.

[0024] Furthermore, step S6 in the aforementioned method for breaking through the top also includes: after filling the orifice with particulate matter, continuing to fill a sealed water column bag of a certain height until the design height of the orifice filling section is reached.

[0025] Furthermore, the filling height of the second explosive layer in the aforementioned top-breaking method is twice the filling height of the first explosive layer. Beneficial effects

[0026] One of the above technical solutions has the following advantages or beneficial effects:

[0027] The double-layer explosive charge structure of this invention replaces a single-layer explosive charge with two layers of explosive charge, allowing for layered filling and blasting. The lower layer has a low explosive charge, while the upper layer has a high explosive charge. The layers are separated by granular material to prevent interference. This structure effectively utilizes the compensation effect of the free surface below the top layer and effectively solves the problem of rock slab clamping caused by a large reserved height of the top layer. It features a reserved height of 6.5-8.0m for breaking through the top, high operational safety, and a small explosive charge but extremely high blasting success rate, effectively resolving the contradiction between reserved height and blasting success rate.

[0028] The double-layer explosive structure of this invention uses a single digital electronic detonator as the detonation component for both explosive layers, and connects to an external detonation network using a low-cost blasting busbar. The detonation component is simple, and successful blasting can be achieved without the use of detonating cord, effectively reducing construction and material costs.

[0029] The roof-breaking method of this invention sets up a double-layer charge structure in a single blast hole, sets digital electronic detonator segments in each blast hole according to the radius of the blast circle, and sets the detonation sequence to a 25ms interval between segments of the same explosive layer, with a delay interval of not less than 75ms between the lower and upper explosive layers. This ensures the continuous action of the blasting energy of the same explosive layer. The upper explosive layer detonates after the rock mass of the lower blasted layer has fully fallen to form a free surface, ensuring the successful blasting of the upper explosive layer. Thus, under the premise of a large reserved roof layer thickness, it effectively guarantees the successful blasting of the roof-breaking operation. Attached Figure Description

[0030] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0031] Figure 1 This refers to a traditional charge structure for VCR-based Faraday well roof breaking;

[0032] Figure 2 This is a schematic diagram of the structure of Embodiment 1 of the present invention;

[0033] Figure 3 This is a schematic diagram of the borehole arrangement and detonator segmentation of the present invention;

[0034] Figure 4 This is a schematic diagram of the structure of Embodiment 2 of the present invention;

[0035] In the figure: 100 borehole; 1 bottom fixing block; 2 bottom filling section; 3 first explosive layer; 4 spacer layer; 5 second explosive layer; 6 orifice filling section; 61 particulate filling section; 62 liquid filling section; 7 digital electronic detonator; 8 digital electronic detonator lead wire. Detailed Implementation

[0036] The present invention will be further described in detail below with reference to embodiments, but the implementation of the present invention is not limited thereto. Example

[0037] This embodiment proposes a double-layer charge structure for well top breaking based on VCR blasting. The structure consists of a bottom fixing block 1, a bottom filling section 2, a first explosive layer 3, a spacer layer 4, a second explosive layer 5, and a hole opening filling section 6 arranged from bottom to top in a reserved top plate layer blast hole 100.

[0038] The hole bottom fixing block 1 is sized to match the inner diameter of the blast hole 100, and the hole bottom fixing block 1 is provided with a lifting ring for hoisting and fixing; preferably, the hole bottom fixing block 1 is a columnar cement block that matches the inner diameter of the blast hole 100.

[0039] The bottom filling section 2, the spacer layer 4, and the orifice filling section 6 are filled with particulate matter, which can be commercially available manufactured sand or other particulate matter of the same particle size. The height of the bottom filling section 2 and the spacer layer 4 is 0.7~1.1m, and the height of the orifice filling section 6 is 1.5~1.9m. The heights of the bottom filling section 2, the spacer layer 4, and the orifice filling section 6 are designed based on the reserved height of the top plate layer blast hole 100 and the amount of explosive charge. The heights of the bottom filling section 2 and the orifice filling section 6 are determined based on the principle of avoiding the blasting energy from dissipating along the axial direction of the blast hole 100, and the height of the spacer layer 4 is determined based on the principle of avoiding the first explosive layer 3 from directly detonating the second explosive layer 5.

[0040] The first explosive layer 3 and the second explosive layer 5 are filled with emulsion explosive. The filling height is calculated based on the total charge to ensure complete blasting of the reserved top layer. The filling height of the first explosive layer 3 is less than the filling height of the second explosive layer 5. Preferably, the filling height of the first explosive layer 3 is half the filling height of the second explosive layer 5. Digital electronic detonators 7 are arranged at the bottom of the first explosive layer 3 and the second explosive layer 5. The digital electronic detonators 7 are connected to the blasting busbar through digital electronic detonator lead wires 8 to form a detonation network.

[0041] like Figure 2 As shown, a preferred implementation parameter of the double-layer charge structure described in the above scheme is as follows: the bottom fixing block 1 is a Φ130mm cylindrical cement block; the bottom filling section 2 and the spacer layer 4 are both filled with machine-made sand to a height of 1.0m; the orifice filling section 6 is filled with machine-made sand to a height of 1.6m; the first explosive layer 3 and the second explosive layer 5 are filled with Φ130mm strip-shaped emulsion explosives; a single digital electronic detonator 7 is tied to the bottom emulsion explosive; the height of the first explosive layer 3 is set to 1.26m; and the height of the second explosive layer 5 is set to 2.6m. Example

[0042] This embodiment proposes a double-layer charge structure for well top breaking based on VCR blasting. The difference between this and Embodiment 1 is that the full-section particle filling method of the orifice filling section 6 is replaced by a combination of particle and liquid filling method. Specifically, the orifice filling section 6 includes a particle filling section 61 and a liquid filling section 62. The particle filling section 61 has a height of not less than 0.5m, and the liquid filling section 62 is filled with a sealed water column bag with a height of not less than 1.0m.

[0043] As in the preferred embodiment of Example 1, the parameters of the orifice filling section 6 of the double-layer charge structure are as follows: the total height of the orifice filling section 6 is 1.6m, of which the height of the machine-made sand filling is 0.6m and the height of the water column bag filling is 1.0m.

[0044] The advantage of this embodiment compared to Embodiment 1 is that, by setting up the water column bag, when the second explosive layer 5 is detonated, the blast energy is transferred to the liquid filling section 62, causing the water column bag to rupture. The liquid inside enters the mechanical sand filling below, which on the one hand reduces the dust generated by the blast, and on the other hand cools and lubricates the particulate filling section 61 to prevent the internal particulate matter from sintering at high temperature, so that the blast energy can be transferred upward and fully act on the blast area, further improving the success rate of the top-breaking blast. Example

[0045] This embodiment proposes a method for well-pulling and roof-breaking based on VCR blasting. On the reserved roof layer, the double-layer charge structure proposed in this invention is evenly distributed in the blast holes arranged around the well-pulling center axis with different radii.

[0046] The method includes the following steps:

[0047] S1: With the shaft axis as the center point, several blasting circles of different radii are laid out. Several boreholes are evenly distributed on each blasting circle. The spacing between the boreholes is designed based on the principle of interaction of blasting energy. The number of blasting circles is determined according to the shaft radius and the borehole spacing. Explosives are filled into the boreholes, and blasting is carried out layer by layer from bottom to top until the remaining rock mass (i.e., the top layer) is 6.5~8.0m thick. The specific thickness of the remaining rock mass is determined according to the actual rock mass type and properties during construction; specifically, such as... Figure 3 As shown, a Φ150mm blast hole 100 is set at the center point of the well, and three blasting circles with different radii are arranged around the blast hole 100. Four blast holes 100 are set on each blasting circle, for a total of 13 blast holes 100. The VCR blasting method is used to blast upwards in layers until the remaining rock mass thickness is 7.5m and then the blasting is stopped.

[0048] S2: Use wires or other ropes to lower the bottom fixing block from the top to the bottom of the blast hole in the remaining rock mass to block the bottom of the blast hole. Fill the bottom with particles to a set height to form a bottom filling section. Specifically, fill the blast hole with manufactured sand to a height of 1.0m.

[0049] S3: Secure a single digital electronic detonator to a strip of emulsion explosive as the detonating warhead, and lower it to the top of the bottom filling section of the hole. Continue to lower the remaining strips of emulsion explosive without digital electronic detonators until the first explosive layer is filled to the designed filling height. Specifically, the filling height of the first explosive layer is 1.26~1.30m.

[0050] S4: Fill the first explosive layer with granular material to the designed height of the spacer layer. Specifically, fill the borehole above the first explosive layer with machine-made sand to a height of 1.0m.

[0051] S5: Fill the second explosive layer using the method in step S3 until the designed filling height of the second explosive layer is reached. The filling height of the second explosive layer is approximately twice the filling height of the first explosive layer. Specifically, the explosive filling height in the second explosive layer is 2.6m.

[0052] S6: Fill the second explosive layer with particulate matter or a combination of particulate matter and liquid to a preset height in the orifice filling section. Specifically, directly fill the borehole above the second explosive layer with machined sand to a height of 1.6m, or first fill the borehole above the second explosive layer with 0.6m high machined sand, and then fill it with a 1.0m high water column bag until the orifice filling section reaches a height of 1.6m.

[0053] S7: Repeat steps S2-S6 to complete the layout of all blast holes in S1. Evenly connect all digital electronic detonator leads 8 to the blasting busbar to form a detonation network. The detonator segment setting method of the detonation network is as follows: the detonation interval of digital electronic detonators in the same explosive layer is 25ms. After the first explosive layer in all blast holes is detonated, the second explosive layer is detonated. The interval between the last detonation of the first explosive layer and the first detonation of the second explosive layer is not less than 75ms.

[0054] S8: After clearing the area and securing all safety exits, detonate within the specified detonation time to carry out the roof breaching operation.

[0055] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the technical scope of the present invention. Therefore, any minor modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A double-layer charge structure for well top breaching based on VCR blasting, characterized in that: In the reserved top plate layer blast hole, from bottom to top, a hole bottom fixing block, a hole bottom filling section, a first explosive layer, a spacer layer, a second explosive layer, and a hole opening filling section are arranged sequentially. The hole bottom filling section, the spacer layer, and the hole opening filling section are filled with particulate matter. The first explosive layer and the second explosive layer are filled with emulsion explosive. Digital electronic detonators are arranged at the bottom of the first explosive layer and the second explosive layer. The digital electronic detonators are connected to the blasting busbar through detonator lead wires to form a detonation network. The height of the bottom filling section and the spacer layer is 0.7~1.1m, and the height of the orifice filling section is 1.5~1.9m; ​​the filling height of the first explosive layer is less than the filling height of the second explosive layer, and the filling height of the first explosive layer is half the filling height of the second explosive layer.

2. The double-layer charging structure for well top breaking based on VCR blasting according to claim 1, characterized in that: The size of the hole bottom fixing block matches the inner diameter of the borehole, and the hole bottom fixing block is provided with a lifting ring for hoisting and fixing.

3. The double-layer charging structure for well top breaking based on VCR blasting according to claim 1, characterized in that: The orifice packing section includes a particulate packing section and a liquid filling section. The particulate packing section has a height of not less than 0.5m, and the liquid filling section is filled with a sealed water column bag with a height of not less than 1.0m.

4. A method for breaking through the roof of a well based on VCR blasting, characterized in that: On the reserved top plate layer, the boreholes arranged around the well center axis with different radii are uniformly provided with a double-layer charge structure as described in any one of claims 1-3.

5. A method for well roof breaking based on VCR blasting according to claim 4, characterized in that: Includes the following steps: S1: With the shaft axis as the center point, several blasting circles with different radii are set up. Several blast holes are evenly arranged on the blasting circles. The spacing between the blast holes is designed based on the principle of interaction of blasting energy. The number of blasting circles is determined according to the shaft radius and the spacing between the blast holes. Explosives are filled into the blast holes and blasting is carried out layer by layer from bottom to top until the remaining rock mass thickness is 6.5~8.0m. S2: Use wire to lower the hole bottom fixing block from the top to the bottom of the hole to block the bottom of the borehole, fill the particulate matter to the set height, and form the hole bottom filling section; S3: Tie a single digital electronic detonator to a strip of emulsion explosive as the detonating warhead, and lower it to the top of the bottom filling section of the hole. Continue to lower the remaining emulsion explosives without digital electronic detonators until the first explosive layer is filled to the designed filling height. S4: Fill the first explosive layer with particulate matter to the designed height of the spacer layer; S5: Fill the second explosive layer using the method in step S3 until the designed filling height of the second explosive layer is reached. The filling height of the second explosive layer is greater than the filling height of the first explosive layer. S6: Fill the second explosive layer with particulate matter to the preset height within the orifice filling section; S7: Repeat steps S2-S6 to complete the layout of all blast holes in S1. Evenly connect all digital electronic detonator leads to the blasting busbar to form a detonation network. The detonator segment setting method of the detonation network is as follows: the detonation interval of digital electronic detonators in the same explosive layer is 25ms. After the first explosive layer in all blast holes is detonated, the second explosive layer is detonated. The interval between the last detonation of the first explosive layer and the first detonation of the second explosive layer is not less than 75ms. S8: After clearing the area and securing all safety exits, detonate within the specified detonation time to carry out the roof breaching operation.

6. A method for well roof breaking based on VCR blasting according to claim 5, characterized in that: Step S6 also includes: after filling the orifice with particulate matter, continue filling the orifice with a sealed water column bag of a set height until the design height of the orifice is reached.

7. A method for well roof breaking based on VCR blasting according to claim 5, characterized in that: The filling height of the second explosive layer is twice that of the first explosive layer.

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