Sectional pressure relief and reinforcement control method of tunnel roof based on double tunneling

Abstract

The present invention provides a method for controlling the segmented pressure relief and reinforcement of the tunnel roof based on double tunnel excavation, including: obtaining geological parameters of the coal seam roof; according to the geological parameters, drilling holes obliquely toward the coal seam roof at the side tunnel wall of the coal pillar in the second tunnel, so that the drilled holes pass through the direct roof of the first tunnel and extend into the basic roof of the mining face; based on the section where the drill hole located at the basic roof is located, hydraulic fracturing is performed on the basic roof; based on the section where the drill hole located at the direct roof is located, grouting reinforcement is performed on the direct roof. The present invention not only optimizes the fracturing and grouting operation procedures in terms of technology and improves the operation efficiency, but also can alleviate the influence of the high advanced support pressure and lateral support pressure caused by the difficulty of hard roof collapse on the stability of the tunnel surrounding rock, improve the structural integrity and bearing capacity of the local roof of the tunnel, transfer the stress above the coal pillar in the section to a certain extent, and achieve the purpose of controlling the deformation of the tunnel surrounding rock.

Description

Technical Field

[0001] The invention relates to the technical field of coal mining, and in particular to a tunnel roof segmented pressure relief and reinforcement control method based on double tunnel excavation. Background Art

[0002] In coal mining, the double-tunnel excavation method with coal pillars is usually used for construction. For example, the first tunnel and the second tunnel are excavated at intervals on one side of the mining face to form a coal pillar between the first tunnel and the second tunnel. Although the double-tunnel excavation technology is simple to manage and the working face connection speed is fast, which is conducive to ventilation, transportation, drainage and safety during construction, during construction, the two tunnels are simultaneously affected by the advance support pressure and lateral support pressure of the working face. The second tunnel excavated in advance as an auxiliary transportation is more susceptible to the impact of mining on both sides, resulting in continuous deformation of the tunnel, which seriously affects ventilation, transportation and working face advancement operations. After the top and bottom construction, the tunnel roof support needs to be re-carried out, and the tunnel maintenance is difficult, which seriously affects the mining progress. In particular, when there is a thick and hard basic roof in the overlying rock stratum, the basic roof is difficult to collapse in time with the mining advancement of the mining face. The high stress accumulated in the coal pillar makes it have a high impact and coal and gas outburst hazard, threatening the safe production of the mine.

[0003] Common methods for controlling tunnel surrounding rock include reinforcement method and pressure relief method. Reinforcement method mainly includes anchor (cable) support, steel support, grouting, etc. Pressure relief method mainly includes drilling pressure relief, hydraulic fracturing, deep hole blasting, etc. Grouting method mainly involves injecting slurry into tunnel surrounding rock at a certain pressure, and then the slurry diffuses and fills the cracks of tunnel broken surrounding rock within a certain range, effectively increasing the integrity of the surrounding rock and the anchor support effect. At the same time, hydraulic fracturing has the technical advantages of safety, efficiency and controllability.

[0004] However, when the coal seam is broken with direct roof and thick hard basic roof, the high advance support pressure and lateral support pressure caused by the hard basic roof that is difficult to collapse in time will put the tunnel surrounding rock in a high stress environment during coal mining, and the broken direct roof will further increase the deformation of the tunnel roof, and the prestressed field of the anchor support is difficult to effectively spread, and a surrounding rock bearing structure with a certain strength cannot be formed. The roof support effect is poor, and it is difficult to control the deformation of the tunnel surrounding rock. In this case, the thick hard basic roof of the mining face is usually unloaded, and the direct roof of the first tunnel is grouting reinforced. However, since the unloading and grouting reinforcement are both carried out in stages in the first tunnel, the construction operation will not only interfere with the coal transportation operation of the mining face of the first tunnel, but also because the unloading and grouting reinforcement are carried out in stages and in stages, the efficiency is low. Summary of the invention

[0005] The present invention provides a tunnel roof segmented pressure relief and reinforcement control method based on double tunneling, which is used to solve or improve the problem that when the pressure relief and reinforcement process is used to control the tunnel surrounding rock in the double tunneling method with coal pillars, the pressure relief and reinforcement process operation affects the transportation operation of the first tunnel and there is a problem of low operation efficiency.

[0006] The present invention provides a method for controlling the segmented pressure relief and reinforcement of the tunnel roof based on double-tunnel excavation, comprising: obtaining geological parameters of the coal seam roof; drilling holes obliquely toward the coal seam roof at the side walls of the coal pillars in the second tunnel according to the geological parameters, so that the drilled holes pass through the direct roof of the first tunnel and extend into the basic roof of the mining face; hydraulic fracturing the basic roof based on the section where the drill holes located at the basic roof are located; and grouting reinforcement of the direct roof based on the section where the drill holes located at the direct roof are located.

[0007] According to a tunnel roof segmented decompression and reinforcement control method based on double-tunnel excavation provided by the present invention, the geological parameters of the coal seam roof include: the stratum height and strength parameters of the direct roof and the stratum height and strength parameters of the basic roof.

[0008] According to a method for controlling the segmented pressure relief and reinforcement of the tunnel roof based on double tunnel excavation provided by the present invention, the step of drilling holes obliquely toward the coal seam roof at the side tunnel walls of the coal pillars in the second tunnel according to geological parameters, so that the drilled holes pass through the direct roof of the first tunnel and extend into the basic roof of the mining working face, comprises: determining the drilling position, drilling direction and drilling length of the borehole according to the geological parameters; and performing drilling construction along the side tunnel walls of the coal pillars toward the coal seam roof according to the drilling position, the drilling direction and the drilling length.

[0009] According to a method for controlling the segmented pressure relief and reinforcement of the tunnel roof based on double-tunnel excavation provided by the present invention, the step of drilling holes obliquely toward the coal seam roof in the coal pillar side tunnel wall in the second tunnel according to geological parameters, so that the drilled holes pass through the direct roof of the first tunnel and extend into the basic roof of the mining working face, further includes: along the mining direction of the mining working face, a plurality of the drill holes are sequentially and spaced apart on the coal pillar side tunnel wall on the front side of the goaf toward the coal seam roof.

[0010] According to a tunnel roof segmented pressure relief and reinforcement control method based on double-tunnel excavation provided by the present invention, a plurality of the drill holes are arranged side by side along the mining direction.

[0011] According to a tunnel roof segmented pressure relief and reinforcement control method based on double-tunnel excavation provided by the present invention, the distance between two adjacent boreholes among the multiple boreholes is the same; or, the distance between two adjacent boreholes among the multiple boreholes is determined based on at least one of mine pressure monitoring data, tunnel pressure conditions and water discharge conditions of adjacent boreholes.

[0012] According to a tunnel roof segmented depressurization and reinforcement control method based on double-tunnel excavation provided by the present invention, the step of hydraulically fracturing the basic top based on the section where the borehole located in the basic top is located includes: determining the position of the first section of the borehole in the basic top and the fracturing parameters for hydraulically fracturing the basic top according to the geological parameters; and hydraulically fracturing the basic top based on the position of the first section and the fracturing parameters.

[0013] According to a tunnel roof segmented depressurization and reinforcement control method based on double-tunnel excavation provided by the present invention, the step of grouting reinforcement of the direct roof based on the section where the drill hole of the direct roof is located includes: determining the position of the second section of the drill hole in the direct roof and the grouting parameters for grouting the direct roof according to the geological parameters; and grouting reinforcement of the direct roof based on the position of the second section and the grouting parameters.

[0014] The present invention provides a method for controlling the segmented pressure relief and reinforcement of the tunnel roof based on double-tunnel excavation. When coal mining encounters the conditions where the coal seam above is a broken direct roof and a thick and hard basic roof, drilling construction is carried out on the side roadway wall of the coal pillar in the second tunnel toward the coal seam roof, and the thick and hard basic roof above the mining working face is pressure relieved based on the same drill hole, and the broken direct roof above the first tunnel is grouting reinforced. This not only solves the mutual interference and influence of the drilling, pressure relief, grouting construction and the mining and transportation process of the first tunnel in terms of technology, but also uses the same drill hole to realize segmented hydraulic fracturing and grouting reinforcement construction, thereby simplifying the operation procedure and improving the operation efficiency.

[0015] At the same time, the present invention weakens the thick and hard basic roof above the mining face of the coal seam near the tunnel area by hydraulic fracturing, so that the roof of the goaf area near the first tunnel can collapse in time, which can reduce the suspended roof area, reduce the influence of the advance support pressure and lateral support pressure of the mining face on the tunnel, reduce the stress concentration level in the roof and coal pillar, control or weaken the strength of the roof pressure and the possible impact, and alleviate the high stress of the surrounding rock of the double tunnels.

[0016] In addition, the present invention can effectively improve the integrity and strength of the local surrounding rock of the tunnel roof by grouting reinforcement at the position of the broken direct roof of the first tunnel, and can effectively diffuse the prestressed field formed by the anchor rod and anchor cable support, increase the strength of the surrounding rock bearing structure, and effectively control the deformation of the surrounding rock of the first tunnel. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 It is a flow chart of a tunnel roof segmented pressure relief and reinforcement control method based on double tunnel excavation provided by the present invention;

[0019] Figure 2 It is a schematic diagram of the top view of the structure of drilling holes on the coal seam roof provided by the present invention;

[0020] Figure 3 The present invention provides Figure 2 Schematic diagram of AA structure.

[0021] Reference numerals:

[0022] 100: coal seam; 110: direct roof; 120: basic roof; 1: first tunnel; 2: coal pillar; 3: second tunnel; 4: mining face; 41: goaf; 5: borehole; 51: first section; 52: second section; 6: fracturing fissure. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] Combine the following Figure 1-Figure 3 The present invention describes a tunnel roof segmented pressure relief and reinforcement control method based on double tunnel excavation.

[0025] like Figure 1 As shown, this embodiment provides a tunnel roof segmented pressure relief and reinforcement control method based on double tunnel excavation, comprising the following steps:

[0026] Step 110, obtaining geological parameters of the coal seam roof.

[0027] Step 120, according to geological parameters, the side walls of the coal pillars in the second tunnel are drilled obliquely toward the coal seam roof, so that the drilled holes pass through the direct roof of the first tunnel and extend into the basic roof of the mining working face.

[0028] Step 130, hydraulically fracturing the base top based on the section where the borehole located at the base top is located.

[0029] Step 140, based on the section where the borehole located at the direct roof is located, grouting reinforcement is performed on the direct roof.

[0030] Specifically, the method shown in this embodiment is aimed at the occurrence conditions of a broken direct roof and a thick and hard basic roof above the coal seam. In coal mining, drilling construction is carried out toward the coal seam roof through the side wall of the coal pillar in the second tunnel, and the thick and hard basic roof above the mining working face is depressurized based on the same drill hole, and the broken direct roof above the first tunnel is grouting reinforced. This not only solves the mutual interference and influence of drilling, depressurization, grouting construction and the coal mining and transportation process of the first tunnel in terms of technology, but also uses the same drill hole to realize segmented hydraulic fracturing and grouting reinforcement construction, thereby simplifying the operation procedure and improving operation efficiency.

[0031] At the same time, this embodiment weakens the thick and hard basic roof above the mining face of the coal seam near the tunnel area by hydraulic fracturing, so that the roof of the goaf area near the first tunnel can collapse in time, thereby reducing the suspended roof area, reducing the influence of the advance support pressure and lateral support pressure of the mining face on the tunnel, reducing the stress concentration level in the roof and coal pillar, controlling or weakening the strength of the roof pressure and the possible impact, and alleviating the high stress of the surrounding rock of the double tunnels.

[0032] In addition, this embodiment can effectively improve the integrity and strength of the local surrounding rock of the tunnel roof by grouting reinforcement at the position of the broken direct roof of the first tunnel, and can effectively diffuse the prestressed field formed by the anchor rod and anchor cable support, increase the strength of the surrounding rock bearing structure, and effectively control the deformation of the surrounding rock of the first tunnel.

[0033] Here, based on the combined effect of segmented pressure relief and grouting reinforcement of the same borehole, the stress environment of the tunnel and section coal pillar can be jointly improved, the surrounding rock can be locally reinforced, and the deformation of the tunnel surrounding rock can be controlled. While ensuring the normal operation of the first tunnel, conditions are provided for the second tunnel to be retained as the return air tunnel of the lower section.

[0034] Among them, this embodiment specifically uses a borehole peep instrument to detect the lithology of the coal seam roof to obtain the geological parameters of the coal seam roof, which include the stratigraphic height and strength parameters of the direct roof and the stratigraphic height and strength parameters of the basic roof.

[0035] In some embodiments, in order to facilitate accurate drilling construction according to the geological parameters of the coal seam roof, the embodiment shows that according to the geological parameters, the side roadway of the coal pillar in the second roadway is inclined to the coal seam roof, so that the drilled hole passes through the direct roof of the first roadway and extends into the basic roof of the mining working face, including but not limited to the following steps:

[0036] According to the geological parameters, the drilling position, drilling direction and drilling length of the borehole are determined; according to the drilling position, drilling direction and drilling length, drilling construction is carried out along the side of the coal pillar towards the coal seam roof.

[0037] The opening position shown in this embodiment is the position where the drilling construction is carried out on the side of the coal pillar, the drilling direction is determined by the angle between the axial direction of the borehole and the horizontal plane, and the drilling length is relative to the length of the borehole. Here, based on the opening position, drilling direction and drilling length of the borehole, this embodiment can use a drilling rig to accurately perform drilling construction to ensure that the drilled hole passes through the direct roof of the first tunnel and extends into the basic roof of the mining working face, so as to prepare for the subsequent staged fracturing and grouting reinforcement of the coal seam roof based on the drilling.

[0038] In some embodiments, in order to ensure the effect of staged fracturing and grouting reinforcement of the coal seam roof, according to the geological parameters shown in this embodiment, the side wall of the coal pillar in the second roadway is inclined to the coal seam roof, so that the drilled hole passes through the direct roof of the first roadway and extends into the basic roof of the mining working face, including but not limited to the following steps:

[0039] Along the mining direction of the mining face, multiple drill holes are drilled in sequence at intervals on the side walls of the coal pillars in front of the goaf, toward the coal seam roof.

[0040] Here, each drill hole constructed in this embodiment is ensured to pass through the direct top of the first tunnel and extend into the basic top of the mining working face. However, the drill holes can be arranged in parallel or form a certain angle with each other, which is not specifically limited here.

[0041] Preferably, in order to ensure the convenience of drilling operations and enhance the effect of staged fracturing and grouting reinforcement of the coal seam roof, the present embodiment arranges the multiple drill holes side by side along the mining direction of the mining face.

[0042] Among them, this embodiment can specifically set the distance between two adjacent boreholes among multiple boreholes to be the same; or, the distance between two adjacent boreholes among multiple boreholes is determined based on at least one of mine pressure monitoring data, tunnel pressure conditions and water discharge conditions of adjacent boreholes.

[0043] In some embodiments, in order to accurately relieve the pressure of the thick and hard basic roof on the upper side of the mining face, the basic roof is hydraulically fractured based on the section where the borehole located at the basic roof is located, including but not limited to the following steps:

[0044] According to the geological parameters, the position of the first section of the borehole in the basic top and the fracturing parameters for hydraulically fracturing the basic top are determined; based on the position of the first section and the fracturing parameters, the basic top is hydraulically fractured.

[0045] In the actual operation process, this embodiment achieves hydraulic fracturing of the thick and hard basic roof on the upper side of the mining working face by delivering the hydraulic fracturing device to the first section of the borehole and controlling fracturing parameters such as water pressure and fracturing time.

[0046] In some embodiments, in order to accurately perform cement grouting reinforcement on the broken direct roof on the upper side of the first tunnel, the direct roof is reinforced by grouting based on the section where the drill hole of the direct roof is located, including but not limited to the following steps:

[0047] According to geological parameters, the position of the second section of the borehole in the immediate roof and the grouting parameters for grouting the immediate roof are determined; based on the position of the second section and the grouting parameters, the immediate roof is reinforced by grouting.

[0048] The grouting parameters shown in this embodiment specifically include grouting pressure, grouting time and grouting position in the second section.

[0049] like Figure 2 and Figure 3 As shown, the present invention takes the mining of a mining face of a mine as an example to introduce the tunnel roof segmented pressure relief and reinforcement control method based on double tunnel excavation shown in the above embodiment, specifically referring to the following steps:

[0050] Step 1: Conduct geomechanical tests on the surrounding rock of the mine in the areas of the first tunnel 1 and the second tunnel 3 excavated in advance to determine the structure and surrounding rock strength of the coal seam roof, obtain the layer height and strength parameters of the direct roof 110 and the basic roof 120, and provide corresponding initial parameters for the construction design of the borehole 5 in the next step. Figure 3 As shown, a coal pillar 2 of a certain width is left between the first tunnel 1 and the second tunnel 3, and the coal seam 100 where the coal pillar 2 is located has an inclination angle θ relative to the horizontal plane.

[0051] Step 2, based on the obtained layer height and strength parameters of the coal seam roof, determine the drilling position of the drill hole 5 in the side roadway of the coal pillar in the second tunnel 3, calculate the arrangement angle of the drill hole 5 and the total drilling length, and at the same time determine the length, position and staged fracturing parameters of the first section 51 of the drill hole 5 in the basic top 120, and determine the length, position and grouting parameters of the second section 52 of the drill hole 5 in the direct top 110.

[0052] Step 3, along the mining direction of the mining face 4, starting from the front side of the goaf 41, at a preset spacing, the side lane of the coal pillar in the second tunnel 3 is drilled upwardly toward the coal seam roof using a drilling machine according to the calculated opening position, drilling direction and drilling length of the drill hole 5, to obtain the drill hole 5. Figure 2 The direction indicated by the arrow is the mining direction.

[0053] Step 4, starting from the initial hole position, follow the operation of step 3 above, and drill a group of multiple boreholes 5 of the same specifications arranged in sequence at a certain design interval along the mining direction of the mining face 4 on the side of the coal pillar in the second tunnel 3. The initial interval between two adjacent boreholes 5 is 8 to 10m. In the later stage, the pressure relief effect can be comprehensively judged through the mine pressure monitoring data, the tunnel pressure situation and the water output of the adjacent boreholes 5, and the interval parameters of the two adjacent boreholes 5 can be adjusted dynamically in real time.

[0054] Step 5, for each drilled hole 5, within the calculated first section 51 of the drilled hole 5, hydraulic fracturing and pressure relief cutting and fracturing construction are carried out at a plurality of pre-designed segmented fracturing positions from top to bottom, so as to form fracturing cracks 6 in the thick and hard basic roof 120 above the mining working face 4, thereby weakening and fracturing the basic roof 120 and reducing the hanging roof area.

[0055] Step 6, after the hydraulic fracturing is completed, the staged fracturing device is taken out from the borehole 5, and according to the calculated position of the second section 52 of the borehole 5, grouting is performed in sequence using cement slurry grouting materials through grouting equipment, so as to grout and reinforce the broken direct top 110 above the first tunnel 1.

[0056] Step 7, since the grouting range of the borehole 5 is limited to a certain extent, a strip grouting area with a certain interval is formed after grouting, and the full-range grouting of the direct top 110 cannot be achieved in the area between two adjacent boreholes 5. At a later stage, according to the stability and deformation of the roof in the tunnel range, a grouting borehole 5 can be drilled in a small range in the first tunnel 1 to the direct top 110 with an anchor drill rig, and additional grouting can be performed.

[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A tunnel roof segmented pressure relief and reinforcement control method based on double tunnel excavation, characterized in that: include: Obtain geological parameters of coal seam roof; According to geological parameters, a hole is drilled obliquely toward the coal seam roof at the side of the coal pillar in the second tunnel, so that the drilled hole passes through the direct roof of the first tunnel and extends into the basic roof of the mining face; the thick and hard basic roof above the mining face is depressurized based on the same drilled hole; Based on the section where the drill hole of the thick hard basic roof above the mining working face near the roadway area of ​​the coal seam is located, hydraulic fracturing is performed on the thick hard basic roof above the mining working face near the roadway area of ​​the coal seam; Based on the section where the drill hole at the broken immediate roof of the first tunnel is located, grouting reinforcement is performed on the broken immediate roof of the first tunnel.

2. The tunnel roof segmented pressure relief and reinforcement control method based on double tunnel excavation according to claim 1 is characterized in that: The geological parameters of the coal seam roof include: the layer height and strength parameters of the direct roof and the layer height and strength parameters of the basic roof.

3. The tunnel roof segmented pressure relief and reinforcement control method based on double tunnel excavation according to claim 1 is characterized in that: The step of drilling holes obliquely toward the coal seam roof in the side lane of the coal pillar in the second lane according to geological parameters so that the drilled holes pass through the direct roof of the first lane and extend into the basic roof of the mining working face includes: Determine the drilling location, drilling direction and drilling length of the borehole according to geological parameters; According to the hole opening position, the drilling direction and the drilling length, drilling construction is performed along the side roadway of the coal pillar toward the coal seam roof.

4. The tunnel roof segmented pressure relief and reinforcement control method based on double tunnel excavation according to claim 1 is characterized in that: The step of drilling a hole obliquely toward the coal seam roof in the side lane of the coal pillar in the second lane according to the geological parameters so that the hole passes through the direct roof of the first lane and extends into the basic roof of the mining working face further includes: Along the mining direction of the mining working face, a plurality of the above-mentioned drill holes are sequentially and spaced apart on the side roadway of the coal pillar in front of the goaf, toward the coal seam roof.

5. The tunnel roof segmented pressure relief and reinforcement control method based on double tunnel excavation according to claim 4 is characterized in that: The plurality of boreholes are arranged side by side along the mining direction.

6. The tunnel roof segmented pressure relief and reinforcement control method based on double tunnel excavation according to claim 5 is characterized in that: The distance between two adjacent bore holes is the same.

7. The method for controlling the segmented pressure relief and reinforcement of the tunnel roof based on double tunneling according to any one of claims 1 to 6, characterized in that: The step of hydraulically fracturing the base top based on the section where the borehole located at the base top is located comprises: Determining, based on the geological parameters, a location of a first section of the borehole in the base roof and fracturing parameters for hydraulically fracturing the base roof; The base top is hydraulically fractured based on the position of the first section and the fracture parameters.

8. The method for controlling the segmented pressure relief and reinforcement of the tunnel roof based on double tunneling according to any one of claims 1 to 6, characterized in that: The step of grouting and reinforcing the direct roof based on the section where the borehole of the direct roof is located comprises: Determining, based on the geological parameters, the position of the second section of the borehole in the immediate roof and grouting parameters for grouting the immediate roof; Based on the position of the second section and the grouting parameters, the direct top is reinforced by grouting.

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