Roadway roof supporting method

Abstract

The invention discloses a roadway roof supporting method which comprises the steps of S1, determining a frozen area, drilling the area to form a mounting hole, and enabling at least part of the mounting hole to be located above a to-be-tunneled coal body; s2, a freezing piece with a freezing medium is installed in the installation hole, and the freezing piece cools the freezing area so as to freeze the freezing area; s3, after the to-be-frozen area is frozen, excavating the to-be-tunneled coal body; and S4, the frozen parts are withdrawn from the mounting holes, anchor rods are mounted in the mounting holes, grouting is conducted, and the steps S1 to S4 are repeated. The roadway roof supporting method has the advantages of being simple in step, good in waterproof performance and the like.

Description

Technical Field

[0001] The present invention relates to the field of tunnel support, and in particular to a tunnel roof support method. Background Art

[0002] Tunnel excavation is the prerequisite for coal mining. At present, the serious imbalance of mining and excavation caused by low excavation efficiency, high labor force and low intelligence level seriously restricts the efficient mining of coal in my country. With the gradual depletion of shallow coal resources, the mining depth of coal mines is getting deeper and deeper, and the stress of surrounding rock in the bottom tunnel increases with the increase of mining depth.

[0003] In the relevant technologies, when encountering surrounding rock with water-rich fissures, the roof will collapse and water seepage will be serious, and the problems of deflection and roof collapse will be prominent, which will seriously affect the normal operations such as tunnel excavation and anchor support and the safety of the operators. The time spent on strengthening roof maintenance and anchor support will increase, and it is strictly forbidden to affect the tunnel excavation operation and limit the excavation efficiency and construction safety. Summary of the invention

[0004] The present invention aims to solve one of the technical problems in the related art at least to a certain extent.

[0005] To this end, an embodiment of the present invention proposes a tunnel roof support method with simple steps, high construction efficiency and low cost.

[0006] The tunnel roof support method according to an embodiment of the present invention includes: S1: determining a freezing area and drilling into the area to form a mounting hole, wherein at least a portion of the mounting hole is located above the coal body to be excavated; S2: installing a freezing component with a freezing medium in the mounting hole, wherein the freezing component cools the freezing area to freeze the freezing area; S3: after the freezing area is frozen, excavating the coal body to be excavated; S4: removing the freezing component from the mounting hole, installing an anchor rod and grouting the mounting hole, and repeating steps S1 to S4.

[0007] The tunnel roof support method of the embodiment of the present invention, through steps S1 to S4, freezes the roof area to be anchored by freezing parts, isolates water seepage from the roof, improves the properties of the roof surrounding rock, and enhances the stability of the roof, thereby solving problems such as roof caving and water seepage, and significantly improving the safety and efficiency of construction in the tunnel.

[0008] In some embodiments, in step S1, the height H of the area to be frozen is determined according to the rock mechanical properties of the tunnel roof rock layer and the water seepage and leakage conditions, the installation hole extends from bottom to top and is inclined toward the direction of the coal body to be excavated, and the angle between the extension direction of the installation hole and the horizontal direction is a, and the length of the installation hole is not less than H / sina.

[0009] In some embodiments, in step S3, a thermometer is used to measure the temperature of the frozen area, so that when the freezing temperature is greater than a preset value, the coal body to be excavated is excavated.

[0010] In some embodiments, there are multiple mounting holes and multiple freezing parts, the multiple mounting holes are spaced apart along the width direction of the lane, and the multiple freezing parts are arranged in the multiple mounting holes in a one-to-one correspondence.

[0011] In some embodiments, according to the mechanical parameters of the tunnel roof, the freezing radius of the freezing part is R1, the grouting radius of the mounting hole is R2, and the distance between two adjacent mounting holes is min{R1, R2}.

[0012] In some embodiments, in step S4, a metal mesh is laid on the top plate of the excavation section to prevent the excavation section from deflecting and roof collapse.

[0013] In some embodiments, in step S3, after the tunnel section excavation is completed, a connecting pipe is used to pass through the frozen area so as to lead out the water above the frozen area through the connecting pipe.

[0014] In some embodiments, the connecting pipe includes a first pipe and multiple second pipes, the first pipe extends along the length direction of the tunnel and is arranged on the top plate of the tunnel, the second pipes are arranged at intervals along the length direction of the tunnel and one end of the second pipe passes through the freezing area and is arranged in the rock formation cracks, and the other end of the second pipe is connected to the first pipe so that the water above the freezing area can be drawn out through the first pipe and the multiple second pipes.

[0015] In some embodiments, in step S3, a water guide groove is provided in the tunnel, and the connecting pipe is connected to the water guide groove so that the water above the freezing area flows into the water guide groove through the connecting pipe.

[0016] In some embodiments, the tunnel roof support method further includes step S5, drilling holes in the frozen area to obtain samples, and performing mechanical property testing on the samples. When the mechanical properties of the samples are lower than preset values, anchor rods or anchor cables are added to the frozen area. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic structural diagram of the tunnel roof support according to an embodiment of the present invention.

[0018] Figure 2 It is a support process diagram of the tunnel roof support according to an embodiment of the present invention.

[0019] Figure 3 yes Figure 2 A partial enlarged view of middle A.

[0020] Figure 4 It is a schematic diagram of the structure of the connecting pipe for supporting the tunnel roof according to an embodiment of the present invention.

[0021] Tunnel roof 1; freezing area 11; mounting hole 12; grouting area 13; anchor rod 2; connecting pipe 3; first pipe 31; second pipe 32. DETAILED DESCRIPTION

[0022] Embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to be used to explain the present invention, but should not be understood as limiting the present invention.

[0023] The following describes a tunnel roof supporting method according to an embodiment of the present invention with reference to the accompanying drawings.

[0024] like Figure 1-4 As shown, the tunnel roof support method according to an embodiment of the present invention includes steps S1 to S4.

[0025] S1: Determine the frozen area 11 and drill the area to form an installation hole 12, at least part of which is located above the coal body to be excavated. Figure 2 As shown, according to the rock mechanical properties of the tunnel roof rock layer and the water seepage and leakage conditions, the freezing area 11 and the grouting area 13 above the coal body to be excavated are determined, and installation holes 12 are drilled in the freezing area 11 and the grouting area 13, and at least part of the installation holes 12 is located above the coal body to be excavated.

[0026] S2: Install the freezing element with freezing medium in the installation hole 12, and the freezing element cools the freezing area 11 to freeze the freezing area 11. Specifically, Figure 1-Figure 2 As shown, the freezing element can be a tube body, and the tube body is filled with a freezing medium (for example, circulating liquid nitrogen). The freezing element is fixedly installed in the installation hole 12, and the freezing area 11 is cooled by the freezing element to freeze the freezing area 11, so that a freezing layer is formed in the tunnel roof 1, and the water in the overlying rock layer cannot pass through the freezing layer, thereby ensuring that there will be no water seepage or leakage in the roof during excavation operations, thereby improving the excavation operation environment.

[0027] S3: After the frozen area 11 is frozen, the coal body to be excavated is excavated. Specifically, when the frozen area 11 is completely frozen, the coal body to be excavated is excavated.

[0028] S4: Remove the frozen part from the installation hole 12, install the anchor rod 2 in the installation hole 12 and perform grouting, and repeat steps S1 to S4. Figure 1-Figure 2As shown, after the coal body is excavated, the frozen parts are taken out from the mounting hole 12. At this time, the mounting hole 12 is a grouting hole. The anchor rod 2 is inserted into the mounting hole 12 and the mounting hole 12 is grouting to reinforce the tunnel. After the grouting is completed, the freezing area 11 and the grouting area 13 above the coal body to be excavated are re-determined to perform freezing, excavation and grouting.

[0029] The tunnel roof support method of the embodiment of the present invention, through steps S1 to S4, freezes the roof area to be anchored by freezing parts, blocks water seepage in the roof, improves the properties of the roof surrounding rock, and enhances the stability of the roof. After the freezing is completed, excavation is carried out, the freezing parts are withdrawn, and the grouting anchor rod 2 is installed in the installation hole 12. After the anchor rod 2 is installed, grouting is carried out, and the grouting material diffuses into the surrounding rock to enrich the surrounding rock cracks to form an anchoring area, and multiple anchoring areas are connected into a whole, so as to improve the properties of the roof surrounding rock and block the problem of water seepage and leakage in the overlying rock. The installation hole can be used as the installation hole 12 and the anchoring hole at the same time, which reduces the construction amount. The freezing parts can be reused to reduce the construction cost. The freezing construction is carried out before excavation in batches, and the single drilling construction amount is small, which reduces the construction time and reduces the impact on excavation.

[0030] In some embodiments, in step S1, the height H of the area 11 to be frozen is determined according to the rock mechanical properties of the rock layer of the tunnel roof 1 and the water seepage and leakage situation, the installation hole 12 extends from bottom to top and is inclined toward the direction of the coal body to be excavated, and the angle between the extension direction of the installation hole 12 and the horizontal direction is a, and the length of the installation hole 12 is not less than H / sina. Specifically, Figure 3 As shown, the height H of the freezing area 11 is determined, and the mounting hole 12 is drilled upward from the bottom of the roof and inclined toward the direction of the coal body to be excavated, so that the freezing area 11 is located on the upper part of the coal body to be excavated, and is within the freezing range of the roof during the excavation operation. The angle between the extension direction of the mounting hole 12 and the left and right directions is a, and the length of the mounting hole 12 is not less than H / sina, so that the height of the mounting hole 12 in the up and down direction is greater than H, and further ensures that the height of the freezing area 11 is greater than the height H of the area 11 to be frozen, so as to ensure that the freezing effect can cover all unstable areas or areas with water hazards.

[0031] In some embodiments, in step S3, a thermometer is used to measure the temperature of the frozen area 11, so that when the freezing temperature is greater than a preset value, the coal body to be excavated is excavated. Specifically, the thermometer is installed on the frozen area 11 and is arranged adjacent to the frozen part, and the temperature in the frozen area 11 is measured by the thermometer. When the freezing temperature is greater than the preset value (in other words, after the frozen area 11 is completely frozen), the excavation area is excavated to excavate the coal body to be excavated, so that the freezing effect of the frozen area 11 is monitored by the thermometer.

[0032] In some embodiments, there are multiple mounting holes 12 and freezing elements, and the multiple mounting holes 12 are spaced apart along the width direction of the lane, and the multiple freezing elements are arranged in a one-to-one correspondence in the multiple mounting holes 12. Specifically, the mounting holes 12 are arranged at equal intervals along the front-to-back direction, and the number of mounting holes 12 and the number of freezing elements are both multiple, and a freezing element is arranged in each mounting hole 12, thereby ensuring that the freezing area covers the entire lane roof, and ensuring the freezing effect and freezing efficiency of the freezing area 11.

[0033] In some embodiments, according to the mechanical parameters of the tunnel roof 1, the freezing radius of the freezing member is R1, the grouting radius of the mounting hole 12 is R2, and the spacing between two adjacent mounting holes 12 is min{R1, R2}. Specifically, Figure 3 As shown, the freezing radius of a single freezing part is R1 (R1 refers to the maximum distance at which the freezing part can effectively freeze the surrounding rock formations during the freezing process), the grouting radius of the mounting hole 12 is R2 (R2 refers to the maximum distance at which the cement slurry or other solidifying materials injected through the mounting hole 12 can effectively fill and reinforce the surrounding rock formations), and the vertical distance between two adjacent mounting holes 12 is R (R is the minimum value of R1 and R2). Selecting the smaller value of R1 and R2 can ensure that all areas that need to be processed can be effectively frozen and grouting reinforced to avoid omissions, and the setting of R can make adjacent freezing areas and grouting areas overlap with each other to ensure that the entire operating range can be effectively covered. This overlapping effect enhances the overall support effect and improves the stability and safety of the tunnel roof.

[0034] In some embodiments, in step S4, a metal mesh is laid on the top plate of the excavation section to prevent the excavation section from deflecting and caving. Specifically, after the excavation coal body is completely excavated, a metal mesh can be laid on the top plate of the excavation section to prevent deflection and caving, thereby ensuring the safety of the workers.

[0035] In some embodiments, in step S3, after the tunnel section excavation is completed, the connecting pipe 3 is used to pass through the frozen area 11 so as to lead the water above the frozen area 11 out through the connecting pipe 3. Specifically, Figure 4As shown, in order to reasonably guide the water in the fissures of the roof rock strata, after the tunnel section is excavated and before the anchor 2 is grouted, the frozen area 11 can be drilled, and then the connecting pipe 3 can be passed through the hole to connect with the fissures in the inner roof rock strata, so that the water above the frozen area 11 can be discharged through the connecting pipe 3. If the fissure water in the roof rock strata accumulates too much, it will cause the water pressure to increase, thereby exerting additional pressure on the roof. The connecting pipe 3 can penetrate the frozen area 11 and drill holes to guide the fissure water to the floor water guide groove to reduce the water pressure of the roof. In addition, high water pressure may cause the surrounding rock to soften or expand, and then cause the roof to sink, deflect, and other problems. The connecting pipe 3 can effectively drain the accumulated water and maintain the stability of the surrounding rock. Finally, the presence of water may weaken the bonding force between the anchor 2 and the surrounding rock, causing the anchor 2 to fail. Discharging water through the connecting pipe 3 can ensure the anchoring effect of the anchor 2 after grouting and improve the reliability of the support system.

[0036] In some embodiments, the connecting pipe 3 includes a first pipe 31 and a plurality of second pipes 32. The first pipe 31 is arranged along the length direction of the lane (eg Figure 1 The second pipe 32 is arranged at intervals along the length direction of the tunnel, and one end of the second pipe 32 passes through the frozen area 11 and is arranged in the rock formation crack, and the other end of the second pipe 32 is connected to the first pipe 31, so that the water above the frozen area 11 is led out through the first pipe 31 and the plurality of second pipes 32. Specifically, as Figure 4 As shown, the first tube 31 is a horizontal tube extending in the left-right direction and is fixed on the tunnel roof 1 by fasteners. There are multiple second tubes 32, and the multiple second tubes 32 extend in the up-down direction. The upper ends of the second tubes 32 pass through the freezing area 11 and extend into the rock cracks. The lower ends of the second tubes 32 are connected to the first tube 31, so that the moisture in the rock cracks is discharged through the first tube 31 and the second tube 32.

[0037] In some embodiments, in step S3, a water guide groove (not shown in the figure) is provided in the tunnel, and the connecting pipe 3 is connected to the water guide groove, so that the water above the frozen area 11 flows into the water guide groove through the connecting pipe 3. Specifically, the water guide groove is provided at the bottom of the tunnel and extends in the left-right direction, and the lower end of the first pipe 31 is connected to the water guide groove, so that the water in the rock formation fissure flows into the water guide groove through the connecting pipe 3, and then flows out of the tunnel through the water guide groove.

[0038] In some embodiments, the tunnel roof support method further includes step S5, drilling holes in the frozen area 11 to obtain samples, and testing the mechanical properties of the samples. When the mechanical properties of the samples are lower than the preset values, anchor rods 2 or anchor cables are added to the frozen area 11. Specifically, during the drilling process, the material in the stratum is taken out by a special drill bit to form a complete cylindrical core sample. The cracks, cavities and other defects in the core are analyzed by the obtained core samples to determine whether there are potential safety hazards. The core samples are analyzed in the laboratory, such as compressive strength test, permeability test, mechanical test, etc., to test whether the grouting is qualified. When the test results are unqualified, anchor rods 2 or anchor cables can be added after excavation to enhance the support effect. At this time, the freezing operation, anchoring operation, and the addition of anchor rods or anchor cables can be carried out simultaneously, reducing the time used for a single cycle of tunnel excavation and anchoring operations, and improving the efficiency of tunnel excavation.

[0039] In some embodiments, drilling and sampling are performed at the midpoint of the line connecting the two anchor rods 2, i.e., the anchoring boundary or overlapping area. In this way, it is possible to visually check whether the grouting material fully fills the predetermined space, and to evaluate the quality and uniformity of the grouting by analyzing the core samples taken out, to ensure that the grouting layer meets the expected design requirements. The anchoring effect between the anchor rod 2 and the surrounding rock is judged by the integrity of the core, and to confirm whether the anchor rod 2 is firmly fixed in the surrounding rock.

[0040] The working process of the tunnel roof support method of the embodiment of the present invention is as follows:

[0041] Determination and analysis of rock mechanical parameters of surrounding rock and roof.

[0042] The height H of the roof that needs to be frozen and grouting-anchored is determined based on the rock mechanical properties of the roof rock strata and the water seepage and leakage conditions.

[0043] Determine the freezing and grouting anchoring range, the freezing radius R1, the grouting radius R2, and determine the freezing and grouting anchoring radius R as the minimum value between R1 and R2 to ensure that the determined operating range can be covered by the freezing operation and the anchoring operation (for example: taking the freezing radius R1 as greater than the grouting radius R2 as an example, take the smaller value R2, and determine the freezing-anchoring radius R as R2).

[0044] The borehole is inclined along the axial direction of the tunnel and toward the heading direction to ensure that the frozen area 11 is above the coal body to be excavated, and that the excavation operation is within the freezing range of the roof. The characteristics of the surrounding rock of this part of the roof are improved to ensure the safety of the operators. In addition, since the frozen layer forms an isolation layer, the water in the overlying rock layer cannot penetrate the frozen layer, thereby ensuring that there will be no water seepage or leakage from the roof during the excavation operation, and improving the excavation operation environment.

[0045] Design the drilling angle and depth, and determine the drilling arrangement and density considering the freezing range and grouting diffusion anchoring range to ensure that the freezing layer and the grouting diffusion anchoring range can be connected as a whole to form a continuous anchoring area.

[0046] The drilling depth is L, the drilling angle is a, and the freezing and grouting anchor radius is R, then H = L*sina

[0047] Make sure that the drilling depth L>H / sina.

[0048] The density of drilling arrangement is a maximum of one drilling hole per R / sina.

[0049] After the freezing and grouting anchoring design is determined, holes are drilled in the roof of the coal body to be excavated, freezing pipes are inserted, freezing liquid is injected to form frozen parts, and the roof is left to freeze.

[0050] At the boundary of the predetermined freezing range, a thermometer is installed to monitor the freezing temperature and freezing effect. The thermometer can be installed in the freezing borehole in the previous step, or placed at the boundary of the predetermined freezing range on the top plate surface.

[0051] When the temperature of the temperature monitor reaches the set temperature, the edge of the predetermined freezing area 11 reaches the set freezing effect, that is, the freezing area 11 of the operation cycle reaches the designed freezing effect, and the temperature monitor is withdrawn. The temperature monitor can be reused many times.

[0052] The tunnel boring machine cutting operation and tunnel excavation are carried out in the area below the frozen layer to excavate a complete tunnel section.

[0053] After the tunnel excavation is completed, the freezing pipe is withdrawn and the cycle freezing operation is completed. The freezing pipe and freezing materials can be reused many times.

[0054] Metal mesh is laid on the top plate of the excavation section to prevent deviation and roof collapse and ensure the safety of workers.

[0055] In order to reasonably drain the water in the fissures of the roof rock strata, after the tunnel section is excavated and before the anchor rod 2 is grouted, holes can be drilled through the anchor layer to install connecting pipes 2 and water guide grooves. The connecting pipes 2 lead from the roof to the corners of the roof, and then lead from the side to the floor water guide groove.

[0056] The hollow grouting anchor rod 2 is installed in the installation hole 12. Since the installation hole 12 has been drilled in the aforementioned freezing operation and the freezing pipe has been withdrawn from the installation hole 12, the installation hole 12 can be used as a second hole for the anchor rod 2, thereby reducing the amount of drilling operations.

[0057] The rod tail of the anchor rod 2 is used to perform grouting operations, install the tray, pre-tighten the nut and other anchoring operations through the hollow grouting hole of the anchor rod 2, so that the pre-tightening force of the anchor rod 2 reaches the set state.

[0058] After waiting for a period of time, a grouting layer is formed in the grouting range, and the anchoring areas of each anchor rod 2 and the grouting area 13 are connected to each other as a whole.

[0059] In order to verify the grouting range and anchoring effect of the grouting layer, core drilling can be carried out at the midpoint of the line connecting the two anchor rods 2, that is, the anchoring boundary or overlapping area, to detect the grouting anchoring effect.

[0060] More preferably, anchor rods 2 or anchor cables can be added after excavation to enhance the support effect. At this time, freezing operations, anchoring operations, and adding anchor rods 2 or anchor cables can be carried out simultaneously, reducing the time used for a single cycle of tunnel excavation and anchoring operations and improving tunnel excavation efficiency.

[0061] The advantages of the tunnel roof support method according to the embodiment of the present invention are as follows:

[0062] 1. The mounting hole 12 is the hole for the anchor rod 2, which reduces the drilling construction workload.

[0063] 2. Improve the rock properties of the roof through the freezing method, reduce the temperature of the roof, and form a frozen layer to prevent water leakage and seepage in the roof, thus completing temporary support.

[0064] 3. Improve the rock properties of the roof through grouting, diffuse the slurry into the cracks of the roof, form a complete grouting layer, prevent water leakage and seepage in the roof, and complete permanent support.

[0065] In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0066] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0067] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection, an electrical connection, or communication with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0068] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0069] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" etc. mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0070] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A tunnel roof support method, characterized in that: include: S1: determining a frozen area and drilling the area to form an installation hole, wherein at least a portion of the installation hole is located above the coal body to be excavated; S2: installing a freezing element having a freezing medium in the installation hole, wherein the freezing element cools the freezing area to freeze the freezing area; S3: after the frozen area is frozen, excavating the coal body to be excavated; S4: withdraw the freezing part from the installation hole, install anchor rods and perform grouting on the installation hole, and repeat steps S1 to S4.

2. The tunnel roof support method according to claim 1, characterized in that: In step S1, the height H of the area to be frozen is determined according to the rock mechanical properties of the tunnel roof rock layer and the water seepage and leakage conditions. The installation hole extends from bottom to top and is inclined toward the direction of the coal body to be excavated. The angle between the extension direction of the installation hole and the horizontal direction is a, and the length of the installation hole is not less than H / sina.

3. The tunnel roof support method according to claim 1, characterized in that: In step S3, the temperature of the frozen area is measured by using a thermometer, so that when the freezing temperature is greater than a preset value, the coal body to be excavated is excavated.

4. The tunnel roof support method according to claim 1, characterized in that: There are multiple mounting holes and multiple freezing parts, and the multiple mounting holes are spaced apart along the width direction of the lane. The multiple freezing parts are arranged in the multiple mounting holes in a one-to-one correspondence.

5. The tunnel roof support method according to claim 4, characterized in that: According to the mechanical parameters of the tunnel roof, the freezing radius of the freezing part is R1, the grouting radius of the mounting hole is R2, and the distance between two adjacent mounting holes is min{R1, R2}.

6. The tunnel roof support method according to claim 1, characterized in that: In step S4, a metal mesh is laid on the top plate of the excavation section to prevent the excavation section from deflecting and roof collapse.

7. The tunnel roof support method according to claim 1, characterized in that: In step S3, after the tunnel section excavation is completed, a connecting pipe is used to pass through the frozen area so as to lead out the water above the frozen area through the connecting pipe.

8. The tunnel roof support method according to claim 7, characterized in that: The connecting pipe includes a first pipe and a plurality of second pipes, the first pipe extends along the length direction of the tunnel and is arranged on the tunnel roof, the second pipes are arranged at intervals along the length direction of the tunnel and one end of the second pipe passes through the freezing area and is arranged in the rock formation cracks, and the other end of the second pipe is connected to the first pipe so that water above the freezing area can be drawn out through the first pipe and the plurality of second pipes.

9. The tunnel roof support method according to claim 7, characterized in that: In step S3, a water guide groove is provided in the tunnel, and the connecting pipe is connected to the water guide groove, so that the water above the freezing area flows into the water guide groove through the connecting pipe.

10. The tunnel roof support method according to claim 1, characterized in that: The method further includes step S5, drilling holes in the frozen area to obtain samples, and testing the mechanical properties of the samples. When the mechanical properties of the samples are lower than a preset value, anchor rods or anchor cables are added to the frozen area.

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