Deep well coal mine tunnel surrounding rock grading support construction method

Abstract

The invention provides a deep well coal mine roadway surrounding rock grading support construction method which comprises the following steps: carrying out geological survey and ground exploration on a to-be-tunneled area, and determining the distribution position of a joint stratum in the to-be-tunneled area; performing advanced detection on the to-be-tunneled area according to the distribution position of the joint stratum to obtain a rock mass of the to-be-tunneled area, and determining geological characteristics and structural integrity characteristics of the rock mass; according to the geological characteristics and the structural integrity characteristics of the rock mass, roadway surrounding rock grades are determined, the roadway surrounding rock grades comprise a plurality of grades, a supporting scheme matched with the roadway surrounding rock grades is determined, and supporting operation is carried out on the excavated deep well coal mine roadway; and carrying out displacement monitoring on the supported roadway surrounding rock until the displacement of the supported roadway surrounding rock converges, and completing the support. The roadway surrounding rock can be graded, the supporting scheme can be correspondingly adjusted, the supporting efficiency is improved, and the stability and safety of the roadway are effectively improved.

Description

Technical Field

[0001] This invention relates to the field of coal mine roadway excavation technology, specifically to a method for graded support construction of surrounding rock in deep coal mine roadways. Background Technology

[0002] In deep coal mine tunnel excavation, the stability of the surrounding rock directly affects the tunneling efficiency of the tunneling machine and the safety of the entire operation. Deep mine environments are uniquely complex, with diverse geological formations. High ground stress is one of the most prominent characteristics of deep mine environments. As the mining depth increases, ground stress continuously increases, exerting a tremendous compressive force on the surrounding rock and causing complex changes in its stress state. Simultaneously, the density of joints varies significantly across different regions. As weak points in the surrounding rock, the distribution and development of joints directly affect the integrity and mechanical properties of the surrounding rock. Due to these factors, the surrounding rock conditions differ significantly at each stage.

[0003] Currently, in deep coal mine roadway excavation technologies, a unified support scheme is generally adopted for the support of the surrounding rock. However, in some areas with poor surrounding rock conditions, the support strength and methods provided by the unified support scheme are insufficient to meet the stability requirements of the surrounding rock in these areas. This leads to deformation, cracking, or even collapse of the surrounding rock during excavation or subsequent use, failing to achieve a stable support effect. In some areas with relatively good surrounding rock conditions, the support measures adopted by the unified support scheme appear overly conservative, resulting in over-support. This not only increases support costs, including the consumption of support materials and the increase in construction time, but may also affect the stress adjustment and release of the surrounding rock itself due to the excessive constraint of the support scheme, which is detrimental to the long-term stability of the surrounding rock and reduces the overall support efficiency. Summary of the Invention

[0004] This invention aims to at least partially solve one of the technical problems in related technologies. To this end, embodiments of this invention propose a method for graded support construction of surrounding rock in deep coal mine roadways, which not only improves support efficiency but also effectively enhances the stability and safety of the roadways, reducing safety risks during coal mining.

[0005] The method for graded support construction of surrounding rock in deep coal mine roadways provided by this invention includes the following steps: Conduct geological surveys and surface explorations of the area to be excavated to determine the distribution of jointed strata within the area to be excavated. Based on the distribution location of the jointed strata, advance exploration is conducted in the area to be excavated to obtain the rock mass of the area to be excavated and to determine the geological characteristics and structural integrity characteristics of the rock mass; Based on the geological characteristics and structural integrity of the rock mass, the surrounding rock grade of the tunnel is determined, and the surrounding rock grade of the tunnel includes multiple levels; Based on the pre-defined mapping relationship between the support scheme and the surrounding rock grade of the roadway, a support scheme matching the surrounding rock grade of the roadway is determined, and support operations are carried out on the deep coal mine roadway after excavation. Displacement monitoring is conducted on the surrounding rock of the supported roadway until the displacement of the supported roadway surrounding rock converges, at which point the support is considered complete.

[0006] In some embodiments, the step of determining the surrounding rock grade of the tunnel based on the geological characteristics and structural integrity characteristics of the rock mass includes: Based on the geological characteristics and structural integrity characteristics of the rock mass, calculate the basic quality indicators of the rock mass; Based on the basic quality indicators of the rock mass and the preset mapping table between the roadway surrounding rock grade and the basic quality indicators, the roadway surrounding rock grade corresponding to the rock mass is matched and determined. The roadway surrounding rock grade includes Grade I, Grade II, Grade III, Grade IV and Grade V surrounding rock, and the stability of the surrounding rock corresponding to Grade I, Grade II, Grade III, Grade IV and Grade V surrounding rock decreases in that order.

[0007] In some embodiments, the geological characteristics of the primary surrounding rock are hard rock, with undeveloped joints, no weak surfaces, and the layered rock strata are very thick or thick layers. The structural integrity characteristics are a massive monolithic structure, and the basic quality index is greater than 550. The geological characteristics of the secondary surrounding rock are hard rock or hard rock interspersed with soft rock, containing 1 to 2 sets of relatively well-developed joints, the layered rock strata are medium to thick or thick, the structural integrity characteristics are rubble-like crushed structure, and the basic quality index is greater than or equal to 451 and less than or equal to 550. The geological characteristics of the third-level surrounding rock are soft rock, containing 1 to 3 sets of relatively well-developed joints, with the layered soft surface destroyed, and the structural integrity characteristics are fragmented mosaic structure, with basic quality index greater than or equal to 351 and less than or equal to 450. The geological characteristics of the fourth-level surrounding rock are soft rock, containing 2 to 3 sets of developed joints, with a fragmented mosaic structure and a basic quality index greater than or equal to 251 and less than or equal to 350. The geological characteristics of the fifth-grade surrounding rock are one of the following: broken relatively soft rock, broken soft rock, extremely soft rock, and extremely broken rock. The structural integrity characteristics are brecciated and loose structure, and the basic quality index is less than or equal to 250.

[0008] In some embodiments, the support scheme includes a primary support scheme, a secondary support scheme, a tertiary support scheme, and a quaternary support scheme. The primary support scheme is matched with the primary and secondary surrounding rock, and the secondary, tertiary, and quaternary support schemes correspond to the roadway surrounding rock grades of tertiary, quaternary, and quinary, respectively.

[0009] In some embodiments, the primary support scheme includes the following steps: Multiple anchor bolt groups are installed at intervals on the surrounding rock of the roadway after excavation, in a direction away from the excavation face. The row spacing between two adjacent anchor bolt groups is 800 to 1000 mm, the spacing between two adjacent anchor bolts in each anchor bolt group is set to 800 mm, and each anchor bolt group contains 14 to 18 anchor bolts. Multiple solid anchor cable groups are installed on the surrounding rock of the roadway where the anchor bolt groups are laid, in a direction away from the excavation face. The spacing between two adjacent solid anchor cable groups is set to 1600 to 2000 mm, and the multiple solid anchor cable groups are arranged in a 7-0-7 pattern. After the solid anchor cable group support is completed, a layer of shotcrete is sprayed within a range of 30m behind the tunneling face to seal the surrounding rock. The thickness of the concrete layer is set to 100±10mm.

[0010] In some embodiments, the secondary support scheme further includes the following steps in addition to the primary support scheme: Multiple high-pressure grouting anchor cable groups are installed on the surrounding rock of the roadway after the sprayed concrete layer, within a range of 30 to 50 meters behind the excavation face. The spacing between two adjacent high-pressure grouting anchor cable groups is set to 1600±200mm, and the multiple high-pressure grouting anchor cable groups are arranged in a 6-0-6 pattern.

[0011] In some embodiments, the grouting material in the high-pressure grouting anchor cable assembly is a nano-modified composite single-liquid grouting material with a particle size D95 < 10 μm.

[0012] In some embodiments, the three-level support scheme includes the following steps: Multiple solid anchor cable groups are installed at intervals on the surrounding rock of the roadway after excavation, in a direction away from the excavation face. The row spacing between two adjacent solid anchor cable groups is 800mm, and the spacing between two adjacent solid anchor cables in each solid anchor cable group is set to 800mm. After the solid anchor cable group support is completed, a layer of shotcrete is sprayed within a range of no more than 30m of the delayed tunneling face to seal the surrounding rock. The thickness of the concrete layer is set to 100±10mm. Multiple high-pressure grouting anchor cable groups are installed on the surrounding rock of the roadway after the sprayed concrete layer, within a range of 30 to 50 meters behind the excavation face. The spacing between two adjacent high-pressure grouting anchor cable groups is set to 1600±200mm, and the multiple high-pressure grouting anchor cable groups are arranged in a 7-0-7 pattern.

[0013] In some embodiments, the level four support scheme further includes the step of: Multiple grouting holes are installed at the tunneling face, with a depth of 10±1 meters and a grouting pressure of less than or equal to 20MPa. Grouting reinforcement is carried out on the sidewall of the roadway in the form of alternating deep holes and shallow holes. The depth of the deep holes is set to 8000±1000mm, the depth of the shallow holes is set to 4000±1000mm, and the grouting pressure is set to 5 to 8MPa. After the grouting reinforcement is completed, multiple solid anchor cable groups are installed at intervals on the surrounding rock of the roadway after excavation, in the direction away from the excavation face. The row spacing between two adjacent solid anchor cable groups is 800mm, and the spacing between two adjacent solid anchor cables in each solid anchor cable group is set to 800mm. After the solid anchor cable group support is completed, a layer of shotcrete is sprayed within a range of 30m behind the tunneling face to seal the surrounding rock. The thickness of the concrete layer is set to 100±10mm. Multiple high-pressure grouting anchor cable groups are installed on the surrounding rock of the roadway after the sprayed concrete layer, within a range of 30 to 50 meters behind the excavation face. The spacing between two adjacent high-pressure grouting anchor cable groups is set to 1600±200mm, and the multiple high-pressure grouting anchor cable groups are arranged in a 7-0-7 pattern.

[0014] In some embodiments, the method for graded support construction of surrounding rock in deep coal mine roadways further includes the following steps: Before tunnel excavation begins, the area to be excavated is pre-grouted and reinforced according to the distribution of jointed strata.

[0015] In summary, the method for graded support of surrounding rock in deep coal mine roadways provided by this invention has at least the following advantages compared with related technologies: This method, by grading the surrounding rock of the roadway and adjusting the support scheme accordingly, not only improves the support efficiency but also effectively enhances the stability and safety of the roadway, reducing safety risks during coal mining. Attached Figure Description

[0016] Figure 1 This is a schematic flowchart of a method for graded support construction of surrounding rock in deep coal mine roadways according to an embodiment of the present invention.

[0017] Figure 2 This is a schematic diagram of the roadway cross-section of the first-level support scheme in the graded support construction method for surrounding rock in deep coal mine roadways provided in an embodiment of the present invention.

[0018] Figure 3 This is a schematic diagram of the roadway development surface of the first-level support scheme in the graded support construction method for deep coal mine roadways provided in an embodiment of the present invention.

[0019] Figure 4 This is a schematic diagram of the roadway cross-section of the secondary support scheme in the graded support construction method for surrounding rock in deep coal mine roadways provided in an embodiment of the present invention.

[0020] Figure 5 This is a schematic diagram of the roadway development surface of the secondary support scheme in the graded support construction method for surrounding rock in deep coal mine roadways provided in an embodiment of the present invention.

[0021] Figure 6 This is a schematic diagram of the roadway cross-section of a three-level support scheme in the graded support construction method for surrounding rock in deep coal mine roadways provided in an embodiment of the present invention.

[0022] Figure 7 This is a schematic diagram of the roadway development surface in the graded support construction method for surrounding rock in deep coal mine roadways provided in an embodiment of the present invention.

[0023] Figure 8 This is a schematic diagram of the arrangement of grouting holes at the cross-section of the roadway in a graded support construction method for surrounding rock in a deep coal mine roadway provided by an embodiment of the present invention.

[0024] Figure 9 This is a side view of the grouting hole in the roadway in a method for graded support of surrounding rock in deep coal mine roadways provided by an embodiment of the present invention.

[0025] Figure 10 This is a top view schematic diagram of the grouting holes in the roadway in a graded support construction method for surrounding rock in a deep coal mine roadway provided by an embodiment of the present invention.

[0026] Figure 11 This is a schematic diagram of the arrangement of deep holes and shallow holes at the cross-section of a deep coal mine roadway in a graded support construction method for surrounding rock in an embodiment of the present invention.

[0027] Figure 12 This is a schematic diagram of the arrangement of deep holes and shallow holes on the roadway development surface in a method for graded support of surrounding rock in deep coal mine roadways provided by an embodiment of the present invention.

[0028] Figure 13 This is a schematic diagram of the drilling structure in the three-hole forming process of the graded support construction method for the surrounding rock of deep coal mine roadways provided in an embodiment of the present invention.

[0029] Figure 14 This is a schematic diagram of the arrangement of boreholes at the cross-section of the roadway in the three-hole drilling process of the three-hole drilling method provided in an embodiment of the present invention for graded support construction of surrounding rock in deep coal mine roadways.

[0030] Attached reference numerals: 110, tunnel; 120, roof; 130, sidewall; 140, floor; 11. Anchor bolt assembly; 111. Anchor bolt; 12. Solid anchor cable assembly; 121. Anchor cable; 13. Surface protection component; 14. High-pressure grouting anchor cable assembly; 141. High-pressure grouting anchor cable; 15. Grouting hole; 16. Deep hole; 17. Shallow hole. Detailed Implementation

[0031] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0032] refer to Figure 1 This is a schematic flowchart illustrating a method for graded support construction of surrounding rock in deep coal mine roadways according to an embodiment of the present invention. The method for graded support construction of surrounding rock in deep coal mine roadways provided by the present invention includes the following steps: S10, Conduct geological surveys and surface explorations of the area to be excavated to determine the distribution of jointed strata within the area to be excavated; S20, based on the distribution location of the jointed strata, conduct advance exploration of the area to be excavated to obtain the rock mass of the area to be excavated, and determine the geological characteristics and structural integrity characteristics of the rock mass; S30. Based on the geological characteristics and structural integrity characteristics of the rock mass, the surrounding rock grade of the tunnel is determined, and the surrounding rock grade of the tunnel includes multiple levels; S40, based on the preset mapping relationship between the support scheme and the surrounding rock grade of the roadway, determine the support scheme that matches the surrounding rock grade of the roadway, and carry out support operations on the deep coal mine roadway after excavation. S50 involves monitoring the displacement of the surrounding rock in the supported roadway until the displacement of the supported roadway surrounding rock converges, at which point the support is considered complete.

[0033] Specifically, after the coal mine mining plan is determined, geological surveys and surface exploration are carried out in the area to be excavated. Geological surveys involve in-depth analysis of the geological structure, stratigraphic characteristics, and geological history of the area through geological mapping and geophysical exploration. Surface exploration involves directly obtaining sample information of underground rock strata using equipment such as drilling rigs; this information can then be used to determine the distribution of jointed strata within the area to be excavated. Jointed strata are a key factor affecting the stability of the surrounding rock in tunnels; if jointed strata are densely developed and have complex orientations, they may significantly reduce the overall strength and stability of the surrounding rock.

[0034] Based on the established distribution of jointed strata, advance exploration of the area to be excavated is conducted, such as through multiple advance exploration boreholes, to obtain information about the rock mass in the area to be excavated. Then, the geological characteristics and structural integrity of this rock mass are determined in detail. Geological characteristics include the properties of the rock mass, mineral composition, and the development of joints and fractures. Structural integrity characteristics refer to the degree of fragmentation of the rock mass. For example, rock mechanics tests are used to determine the compressive strength, tensile strength, and other mechanical parameters of the rock mass, and combined with the distribution of joints and fractures, the structural integrity of the rock mass is assessed.

[0035] Then, based on the determined geological characteristics and structural integrity of the rock mass, the surrounding rock grade of the roadway is determined. The surrounding rock grade can include multiple levels, each corresponding to different rock stability and support requirements. Then, based on the determined surrounding rock grade, a matching support scheme is found and determined from the pre-defined mapping relationship between support schemes and surrounding rock grades. Subsequently, support operations are implemented in the excavated deep-shaft coal mine roadway according to this support scheme. Finally, displacement monitoring is performed on the supported surrounding rock, including the convergence deformation of the surrounding rock, roof subsidence, and floor heave. By periodically measuring and recording these data, the deformation trend and rate of the surrounding rock are analyzed. During the monitoring process, a reasonable convergence standard is set. When the displacement of the supported surrounding rock converges, i.e., the deformation no longer increases and tends to stabilize, and meets the pre-set convergence standard, the support is considered complete. At this point, the surrounding rock of the roadway can be considered to have reached a stable state under the current support conditions, ensuring the safe operation of coal mining.

[0036] In summary, the graded support construction method for deep coal mine roadways provided by this invention not only improves support efficiency by grading the surrounding rock of the roadway and adjusting the support scheme accordingly, but also effectively improves the stability and safety of the roadway and reduces safety risks during coal mining.

[0037] In some embodiments, the step of determining the surrounding rock grade of the tunnel based on the geological characteristics and structural integrity characteristics of the rock mass includes: Based on the geological characteristics and structural integrity characteristics of the rock mass, calculate the basic quality indicators of the rock mass; Based on the basic quality indicators of the rock mass and the preset mapping table between the roadway surrounding rock grade and the basic quality indicators, the roadway surrounding rock grade corresponding to the rock mass is matched and determined. The roadway surrounding rock grade includes Grade I, Grade II, Grade III, Grade IV and Grade V surrounding rock, and the stability of the surrounding rock corresponding to Grade I, Grade II, Grade III, Grade IV and Grade V surrounding rock decreases in that order.

[0038] Specifically, the geological characteristics of a rock mass include its lithology, such as whether it is hard rock (e.g., granite, quartzite, etc., rocks with high strength and hardness) or soft rock (e.g., mudstone, shale, etc., rocks with relatively low strength); the degree of joint development, including the number and spacing of joints; the presence of weak surfaces, which may significantly reduce the overall strength of the rock mass; and the thickness of layered rock strata, categorized into different types such as super-thick, thick, medium-thick, and thin layers. Structural integrity characteristics mainly focus on the degree of fragmentation and structural type of the rock mass, such as massive monolithic structure, rubble-like crushed structure, fragmented mosaic structure, and brecciated rubble-like loose structure. In the calculation of basic quality indicators, all of the above factors are comprehensively considered, and these factors are integrated and calculated using a mathematical model to obtain the corresponding basic quality indicators for the rock mass.

[0039] After calculating the basic quality indicators of the rock mass, a precise match is performed based on a pre-defined mapping table between the roadway surrounding rock grade and the basic quality indicators to determine the corresponding roadway surrounding rock grade. This mapping table is derived from extensive engineering practice, theoretical research, and data analysis, and is scientifically sound and reliable. Roadway surrounding rock grades are divided into five levels: Grade I, Grade II, Grade III, Grade IV, and Grade V. Different grades of surrounding rock exhibit significant differences in geological characteristics and structural integrity, as detailed below: The geological characteristics of the primary surrounding rock are as follows: hard rock (uniaxial saturated compressive strength Rc > 40 MPa), with undeveloped joints, no weak surfaces, and layered rock strata that are extremely thick or very thick. The structural integrity characteristics are a massive, integral structure, and the basic quality index is greater than 550. The primary surrounding rock is only slightly affected by geological structures.

[0040] The geological characteristics of the secondary surrounding rock are hard rock (Rc > 30 MPa) or hard rock interspersed with soft rock, containing 1 to 2 sets of relatively well-developed joints, with medium to thick or thick layered rock strata, and a crushed, boulders-like structure. The basic quality index is greater than or equal to 451 and less than or equal to 550. The occurrence and combination of joints within the secondary surrounding rock are unlikely to cause sliding, and the bonding of the layered rock strata is generally good.

[0041] Of course, in some embodiments, the geological characteristics of the secondary surrounding rock may also be relatively soft rock (Rc > 20 to 30 MPa); severely affected by geological structure, containing 1 to 2 sets of relatively well-developed joints, with layered weak surfaces (or interlayers), but their occurrence and combination relationship are not enough to cause sliding; the layered rock layers are thin or medium-thick layers, with poor interlayer bonding and many separation phenomena.

[0042] The geological characteristics of the third-level surrounding rock are soft rock (Rc>10 to 30 MPa), containing 1 to 3 sets of relatively well-developed joints, with the layered soft surface destroyed, and the structural integrity characteristics are fragmented mosaic structure, with basic quality index greater than or equal to 351 and less than or equal to 450.

[0043] The geological characteristics of the fourth-level surrounding rock are soft rock, containing 2 to 3 sets of developed joints, with a fragmented mosaic structure and a basic quality index greater than or equal to 251 and less than or equal to 350.

[0044] The geological characteristics of the fifth-grade surrounding rock are one of the following: broken relatively soft rock, broken soft rock, extremely soft rock, and extremely broken rock. The structural integrity characteristics are brecciated and loose structure, and the basic quality index is less than or equal to 250.

[0045] Furthermore, it should be noted that the surrounding rock grade also has corresponding requirements for the stability state after tunnel excavation. Specifically, for Grade I surrounding rock, the stability state after excavation is that the surrounding rock is stable with no collapse; for Grade II surrounding rock, the stability state after excavation is that the exposure time is long, with a chance of local collapse, the sidewalls are stable, but the roof of the gently sloping rock strata with poor interlayer bonding has a chance of collapse; for Grade III surrounding rock, the stability state after excavation is that small-scale collapse will occur when the tunnel arch is unsupported, and small-scale collapse will occur on the sidewalls; for Grade IV surrounding rock, the stability state after excavation is that large-scale collapse will occur when the arch is unsupported, and the sidewalls will lose stability and cause significant collapse; for Grade V surrounding rock, the stability state after excavation is that the surrounding rock has a high probability of collapse.

[0046] like Figures 2 to 8 As shown, in some embodiments, the support scheme includes a primary support scheme, a secondary support scheme, a tertiary support scheme, and a quaternary support scheme. The primary support scheme is matched with the primary and secondary surrounding rock, and the secondary, tertiary, and quaternary support schemes correspond to the roadway surrounding rock grades of tertiary, quaternary, and quinary, respectively.

[0047] Among them, Class I and Class II surrounding rock have relatively good geological characteristics and structural integrity, and possess high strength and stability. Class I support schemes are mainly matched with Class I and Class II surrounding rock, focusing primarily on simple reinforcement and protection measures, such as a combination of high-strength anchor wire mesh and shotcrete sealing. Specifically, for example... Figure 2 , Figure 3 The support scheme shown may include the following steps: Multiple anchor bolt groups are installed at intervals on the surrounding rock of the roadway after excavation, in a direction away from the excavation face. The spacing between two adjacent anchor bolt groups is 800 to 1000 mm. The spacing between two adjacent anchor bolts in each anchor bolt group is set to 800 mm. Each anchor bolt group contains 14 to 18 anchor bolts, such as 14, 15, 16, 18, etc. Multiple solid anchor cable groups are installed on the surrounding rock of the roadway where the anchor bolt groups are laid, in a direction away from the excavation face. The spacing between two adjacent solid anchor cable groups is set to 1600 to 2000 mm, and the multiple solid anchor cable groups are arranged in a 7-0-7 pattern. After the solid anchor cable group support is completed, a layer of shotcrete is sprayed within a range of 30m behind the tunneling face to seal the surrounding rock. The thickness of the concrete layer is set to 100±10mm.

[0048] In this embodiment, as Figure 2 As shown, the coal mine roadway 110 includes a roof 120, side walls 130, and a floor 140. Anchor bolt groups and solid anchor cable groups are both installed on the roof 120 and side walls 130. The anchor bolts 111 within the anchor bolt group 11 are of the following type and specifications: MSGLW-500 / 22×2800 steel, with a Φ22mm left-handed threaded steel bar without longitudinal reinforcement, a length of 2800±1000mm, and an M24mm thread at the end. Multiple anchor bolts located at the same distance from the tunnel face in the direction away from the tunnel face can form an anchor bolt group. The interval between two adjacent anchor bolt groups is the row spacing. Each anchor bolt within an anchor bolt group is installed perpendicular to the roadway (a 5° error is allowed for construction purposes). The pre-tightening torque of the anchor bolts is greater than or equal to 400 N·m and less than or equal to 550 N·m. Pre-tightening is completed within half an hour after the anchor bolts 111 are installed. Figure 3 As shown in this embodiment, each anchor bolt group 11 contains 15 anchor bolts 111.

[0049] The anchor bolt 111 is anchored using resin-extended anchoring, employing two resin anchoring agents, one MSK2550 and the other MSZ2550. The drilled hole diameter is Φ32mm, the anchoring length is 1157mm, and the anchoring force is less than or equal to 190kN. The anchor bolt tray on the bolt is a high-strength arched tray of 150×150×12mm, equipped with a self-aligning ball pad and nylon gasket.

[0050] The solid anchor cable assembly 12 is installed on the surrounding rock of the roadway away from the tunnel face, and positioned close to the tunnel face. The anchor cable 121 has a diameter of 21.8 mm and a length of 6300 ± 1000 mm. The anchor cable tray used for the anchor cable 121 on the solid anchor cable assembly is a high-strength arched tray of 300 × 300 × 16 mm, equipped with a self-aligning ball pad, requiring a tray bearing capacity greater than 583 kN.

[0051] It should be noted that the 7-0-7 arrangement means that each of the aforementioned physical anchor cable groups 12 is located between two adjacent anchor bolt groups 11, and there are two anchor bolt groups 11 between two adjacent physical anchor cable groups 12. Here, "7" and "0" refer to the number of physical anchor cables within each row of physical anchor cable groups. Figure 3 As shown, the multiple anchor bolt groups in the roadway surrounding rock along the direction away from the excavation face can be sequentially named as: Group 1 anchor bolt, Group 2 anchor bolt, Group 3 anchor bolt, Group 4 anchor bolt, Group 5 anchor bolt, and Group 6 anchor bolt. The multiple physical anchor bolt groups are located between Group 1 and Group 2, Group 3 and Group 4, and Group 5 and Group 6 anchor bolts, respectively. Figure 3 In this context, L1 refers to the row spacing between two adjacent anchor bolt groups, L2 refers to the spacing between two adjacent anchor bolts within each anchor bolt group, and L3 refers to the row spacing between two adjacent physical anchor cable groups.

[0052] The anchoring method for the anchor cables in the solid anchor cable group is as follows: resin end anchoring, using three anchoring agents, one MSK2550 and two MSZ2550. The drilled hole diameter is 32mm, the anchoring length is 1736mm, the initial tension is 300kN, and the preload after locking loss is not less than 250kN.

[0053] In addition, the solid anchor cable assembly also includes a protective surface component 13, which uses a Φ6mm steel mesh with a size of 2500×1000mm and a mesh size of 70mm×70mm. When laying the mesh, it should be pulled tight and compacted, with an overlap length of 70mm. The overlap is made of 16# double-strand iron wire in a three-flower knot manner, and the connection point spacing is ≤140mm.

[0054] After the solid anchor cable support is completed, shotcrete is applied to seal the surrounding rock within a 30m radius of the delayed excavation face. The shotcrete thickness is 100mm, the shotcrete strength is C20, and the volumetric mix ratio (cement:sand:aggregate) is 1:2:2. The accelerator is added at 3% to 5% of the cement weight, and the water-cement ratio is 0.46. The cement grade is P.O42.5R, the sand is medium-coarse sand, and the aggregate particle size is 5 to 10mm.

[0055] like Figure 4 and Figure 5 As shown, in this embodiment, the surrounding rock grade corresponding to the secondary support scheme is grade III. The secondary support scheme is a reinforcement and optimization based on the primary support scheme. In addition to continuing to use anchor bolts and shotcrete support, anchor cable support is also added. For example, the secondary support scheme further includes the following steps based on the primary support scheme: Multiple high-pressure grouting anchor cable groups are installed on the surrounding rock of the roadway after the sprayed concrete layer, within a range of 30 to 50 meters behind the excavation face. The spacing between two adjacent high-pressure grouting anchor cable groups is set to 1600±200mm, and the multiple high-pressure grouting anchor cable groups are arranged in a 6-0-6 pattern.

[0056] The high-pressure grouting anchor 141 within the high-pressure grouting anchor group 14 has the following form and specifications: SKZ21.8-1×19 / 1860-6300, nominal diameter 22mm, length 6300mm, strength 1860MPa, breaking load >460kN, maximum force total elongation >4%, sealing pressure >20MPa. After normal anchoring and prestressing, high-pressure grouting is performed using a hollow tube. Compared with conventional grouting anchors, it has stronger load-bearing capacity, can apply high prestress, is resistant to high pressure, and the sealing pressure is increased by more than 5 times, significantly improving the grouting effect. The anchor diameter of the high-pressure grouting anchor 141 is 21.8mm, and the length is 6300±1000mm. The anchor tray used for the high-pressure grouting anchor 141 is a 300×300×16mm high-strength arched tray, equipped with a self-aligning ball pad, requiring the tray to have a load-bearing capacity greater than 583kN.

[0057] The anchoring method for high-pressure grouting anchor cables is resin end anchoring, using three MSZ2550 anchoring agents. The drilled hole diameter is 36mm, the anchoring length is 1553mm, the initial tension is 300kN, and the preload after locking loss is not less than 250kN.

[0058] It should be noted that in the 6-0-6 arrangement, "6" and "0" refer to the number of high-pressure grouting anchors in each row of high-pressure grouting anchor groups. As shown in the figure, along the direction away from the tunnel face in the surrounding rock, the anchor groups can be named as: Group 1, Group 2, Group 3, Group 4, Group 5, and Group 6. Multiple physical anchor groups are located between Group 1 and Group 2, Group 3 and Group 4, and Group 5 and Group 6, respectively; multiple high-pressure grouting anchor groups are located between Group 2 and Group 3, and Group 4 and Group 5, respectively.

[0059] Furthermore, the grouting material within the high-pressure grouting anchor cable assembly is a nano-modified composite single-liquid grouting material with a particle size D95 < 10 μm. The initial setting time of the nano-modified composite single-liquid grouting material is adjustable from 30 min to 120 min, with a 28-day compressive strength ≥ 90 MPa, a 28-day flexural strength ≥ 9 MPa, a 28-day bond strength with rock mass ≥ 3.5 MPa, and a maximum reaction temperature < 25℃. Moreover, the high-pressure grouting anchor cable employs hollow tube grouting, with a grouting pressure of 5 to 20 MPa.

[0060] like Figure 6 and Figure 7 As shown, in some embodiments, the three-level support scheme is mainly for level 4 surrounding rock, and the three-level support scheme may include the following steps: Multiple solid anchor cable groups are installed at intervals on the surrounding rock of the roadway after excavation, in a direction away from the excavation face. The row spacing between two adjacent solid anchor cable groups is 800mm, and the spacing between two adjacent solid anchor cables in each solid anchor cable group is set to 800mm. After the solid anchor cable group support is completed, a layer of shotcrete is sprayed within a range of no more than 30m of the delayed tunneling face to seal the surrounding rock. The thickness of the concrete layer is set to 100±10mm. Multiple high-pressure grouting anchor cable groups are installed on the surrounding rock of the roadway after the sprayed concrete layer, within a range of 30 to 50 meters behind the excavation face. The spacing between two adjacent high-pressure grouting anchor cable groups is set to 1600±200mm, and the multiple high-pressure grouting anchor cable groups are arranged in a 7-0-7 pattern.

[0061] Specifically, the form and specifications of the solid anchor 121 within the solid anchor group 12 are as follows: SKP21.8-1×19 / 1860-6300 / 4100 anchor cable body. The solid anchor 121 within the solid anchor group 12 can be a top plate anchor or a side anchor; the length of the top plate anchor is 6300±1000mm, and the length of the side anchor is 4100±1000mm. The anchor tray used for the solid anchor 121 within the solid anchor group 12 is a 300×300×16mm high-strength arched tray, paired with a self-aligning ball pad, requiring a tray bearing capacity greater than 583kN. The anchoring method for the solid anchors within the solid anchor group is resin end anchoring, using three anchoring agents: one MSK2550 and two MSZ2550. The borehole diameter is 32mm, the anchorage length is 1736mm, the initial tension is 300kN, and the preload after locking loss is not less than 250kN.

[0062] In addition, the solid anchor cable assembly also includes a protective surface component 13, which uses a Φ6mm steel mesh with a size of 2500×1000mm and a mesh size of 70mm×70mm. When laying the mesh, it should be pulled tight and compacted, with an overlap length of 70mm. The overlap is made of 16# double-strand iron wire in a three-flower knot manner, and the connection point spacing is ≤140mm.

[0063] After the solid anchor cable support is completed, shotcrete is applied to seal the surrounding rock within a 30m radius of the delayed excavation face. The shotcrete thickness is 100mm, the shotcrete strength is C20, and the volumetric mix ratio (cement:sand:aggregate) is 1:2:2. The accelerator is added at 3% to 5% of the cement weight, and the water-cement ratio is 0.46. The cement grade is P.O42.5R, the sand is medium-coarse sand, and the aggregate particle size is 5 to 10mm.

[0064] Subsequently, multiple high-pressure grouting anchor cable groups 14 were installed on the surrounding rock of the roadway after the sprayed concrete layer, within a range of 30 to 50 meters behind the excavation face, to perform high-pressure anchoring and strengthen the support of the roadway. If the roadway in the soft rock section deforms rapidly, grouting anchor cables were promptly installed in alternating rows on the basis of solid anchor cables for timely grouting reinforcement.

[0065] Among them, the high-pressure grouting anchor cable 141 in the high-pressure grouting anchor cable group 14 has the following form and specifications: SKZ21.8-1×19 / 1860-6300, nominal diameter of 22mm, top plate grouting length of 6300mm, strength of 1860MPa, breaking load >460kN, maximum force total elongation >4%, sealing pressure >20MPa. After normal anchoring and application of prestress, high-pressure grouting is carried out using hollow tubes. Compared with conventional grouting anchor cables, it has strong bearing capacity, can apply high prestress, is resistant to high pressure, and the sealing pressure is increased by more than 5 times, which greatly improves the grouting effect.

[0066] The high-pressure grouting anchor cable in the high-pressure grouting anchor cable assembly has the following form and specifications: SKZ21.8-1×19 / 1860-6300, nominal diameter 22mm, length 6300mm, strength 1860MPa, breaking load >460kN, maximum force total elongation >4%, sealing pressure >20MPa. After normal anchoring and prestressing, high-pressure grouting is performed using a hollow tube. Compared with conventional grouting anchor cables, it has stronger load-bearing capacity, can apply high prestress, is resistant to high pressure, and the sealing pressure is increased by more than 5 times, significantly improving the grouting effect. The anchor cable diameter of the high-pressure grouting anchor cable is 21.8mm, and the length is 6300±1000mm. The anchor cable tray used for the high-pressure grouting anchor cable is a 300×300×16mm high-strength arched tray, matched with a self-aligning ball pad, requiring the tray load-bearing capacity to be greater than 583kN.

[0067] The anchoring method for high-pressure grouting anchor cables is resin end anchoring, using three MSZ2550 anchoring agents. The drilled hole diameter is 36mm, the anchoring length is 1553mm, the initial tension is 300kN, and the preload after locking loss is not less than 250kN.

[0068] It should be noted that in the 7-0-7 arrangement, "7" and "0" refer to the number of high-pressure grouting anchors in each row of high-pressure grouting anchor groups. For example, Figure 7 As shown, the surrounding rock of the multiple solid anchor cable groups in the roadway can be named sequentially along the direction away from the excavation face as: the first group of anchor cables, the second group of anchor cables, the third group of anchor cables, the fourth group of anchor cables, the fifth group of anchor cables, and the sixth group of anchor cables. The multiple high-pressure grouting anchor cable groups 14 are located between the second group of anchor cables and the third group of anchor cables, the fourth group of anchor cables, and the fifth group of anchor cables, respectively.

[0069] Furthermore, the grouting material within the high-pressure grouting anchor cable assembly is a nano-modified composite single-liquid grouting material with a particle size D95 < 10 μm. The initial setting time of the nano-modified composite single-liquid grouting material is adjustable from 30 min to 120 min, with a 28-day compressive strength ≥ 90 MPa, a 28-day flexural strength ≥ 9 MPa, a 28-day bond strength with rock mass ≥ 3.5 MPa, and a maximum reaction temperature < 25℃. Moreover, the high-pressure grouting anchor cable employs hollow tube grouting, with a grouting pressure of 5 to 20 MPa.

[0070] Furthermore, the three-level support scheme also includes: laying 3 to 5 anchor cable beams within a range of 30 to 50 meters behind the tunnel face in the surrounding rock, with each anchor cable beam connecting three adjacent solid anchor cables to enhance the overall support strength.

[0071] like Figure 8 , Figure 9 , Figure 10 , Figure 11 and Figure 12 As shown, in some embodiments, the Level IV support scheme corresponds to Level V surrounding rock, and the Level IV support scheme is a further reinforcement based on the Level III support scheme. For example, the Level IV support scheme may include the following steps: Multiple grouting holes 15 are arranged at the tunneling face, the depth of the grouting holes 15 is set to 10±1 meters, and the grouting pressure is less than or equal to 20MPa; Grouting reinforcement is carried out on the sidewall of the roadway in the form of alternating deep holes 16 and shallow holes 17. The depth of the deep holes is set to 8000±1000mm, the depth of the shallow holes is set to 4000±1000mm, and the grouting pressure is set to 5 to 8MPa. After the grouting reinforcement is completed, multiple solid anchor cable groups are installed at intervals on the surrounding rock of the roadway after excavation, in the direction away from the excavation face. The row spacing between two adjacent solid anchor cable groups is 800mm, and the spacing between two adjacent solid anchor cables in each solid anchor cable group is set to 800mm. After the solid anchor cable group support is completed, a layer of shotcrete is sprayed within a range of 30m behind the tunneling face to seal the surrounding rock. The thickness of the concrete layer is set to 100±10mm. Multiple high-pressure grouting anchor cable groups are installed on the surrounding rock of the roadway after the sprayed concrete layer, within a range of 30 to 50 meters behind the excavation face. The spacing between two adjacent high-pressure grouting anchor cable groups is set to 1600±200mm, and the multiple high-pressure grouting anchor cable groups are arranged in a 7-0-7 pattern.

[0072] In this embodiment, five grouting holes are arranged at the tunneling face facing the area to be tunneled. The depth of the grouting holes is 10 meters, the grouting pressure is less than or equal to 20 MPa, and the grouting material is a polyurethane-based chemical grout. An interval grouting sequence is adopted, that is, grouting is first performed on the grouting holes at the bottom of the two sidewalls, then grouting is performed on the grouting holes in the middle of the roof, and then grouting is performed on the sidewall grouting holes again, as shown in the figure. The five grouting holes in this embodiment are named holes 1 to 5, and the grouting sequence can be: 1→5→3→2→4.

[0073] The grouting hole at the middle position of the roof (i.e., hole No. 3) is set diagonally upwards towards the direction of excavation, with an angle α of 10 to 15° between the grouting hole and the direction of excavation, such as 10°, 13°, or 15°. Holes No. 1, 2, 4, and 5 are set out from the excavation face along the direction of excavation towards the outer sidewall, and the angle β formed with the excavation face is 80°. The vertical distance between holes No. 1 and No. 5 and the center of the roadway is 1.3 meters, the vertical distance between holes No. 2 and No. 4 and the center of the roadway is 2.3 meters, and the vertical distance between hole No. 3 and the center of the roadway is 2.6 meters.

[0074] During the reinforcement of the tunnel sidewalls, the grouting material used in both deep and shallow holes is a nano-modified grout with a pore size of 35 to 42 mm.

[0075] In addition, such as Figure 12 As shown, deep holes 16 and shallow holes 17 are spaced apart on the sidewall of the roadway away from the tunneling face. That is, multiple deep holes and shallow holes at the same distance from the tunneling face form deep hole groups and shallow hole groups, respectively. The deep hole groups are located between two adjacent shallow hole groups. In this embodiment, there are two shallow hole groups, each containing six shallow holes; and one deep hole group, containing four deep holes.

[0076] In addition, in the three-level support scheme and the four-level support scheme, the row spacing of two adjacent solid anchor cable groups, the spacing between two adjacent solid anchor cables in each solid anchor cable group, and the row spacing of two adjacent high-pressure grouting anchor cable groups can refer to L1, L2, and L3 in the first-level support scheme and the second-level support scheme, and will not be elaborated here.

[0077] like Figures 13 to 14 As shown, in some embodiments, the method for graded support construction of surrounding rock in deep coal mine roadways further includes the step of: before the roadway excavation begins, pre-grouting reinforcement is carried out on the area to be excavated according to the distribution location of jointed strata.

[0078] Specifically, before tunnel excavation, directional boreholes are used to pre-grout jointed rock strata and fault fracture zones for reinforcement. For example, the borehole layout adopts a 4-hole group 16-branch structure, including 8 treatment holes and 8 advance exploration holes; a three-section drilling process is adopted, namely, the first section is a near-straight hole casing section L4, the second section is a directional inclined casing section L5, and the third section is a bare hole section along the tunnel L6; grouting adopts an automated continuous grouting system, segmented downward type, and closed-mouth static pressure grouting method, with a final grouting pressure of 10 to 16 MPa.

[0079] Furthermore, the exposed borehole section L6 along the roadway can have multiple branch holes, which extend radially along the roadway, forming a large reinforced area within the surrounding rock region and helping to improve the strength of the surrounding rock. Figure 14 The dashed circle around the bare hole section L6 in the tunnel is the reinforced area formed by multiple branch holes, and the arrow Po is the squeezing force exerted by the surrounding rock on the tunnel.

[0080] Furthermore, in this embodiment, the step of monitoring the displacement of the supported roadway surrounding rock in the graded support construction method for deep coal mine roadways provided by the present invention, until the displacement of the supported roadway surrounding rock converges, indicates that the support is complete, includes: Displacement monitoring of the surrounding rock in the supported roadway; If displacement or shift occurs in the surrounding rock of the supported roadway, high-pressure self-sealing hollow grouting anchor cables will be used for reinforcement. The anchor cable structure consists of 19 wires with a diameter of 21.8 mm and a breaking load of 440-520 kN; the sealing pressure reaches over 25 MPa, and the maximum grouting pressure is 31.45 MPa; the grouting material is a rock-compatible high-strength nano-modified inorganic-organic composite material with a particle size (D90) <10 μm, a 28-day compressive strength of 60 MPa, and a bond strength of 3.59 MPa. The support is complete when the displacement of the surrounding rock in the supported tunnel converges.

[0081] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0082] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0083] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0084] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0085] In this invention, the terms "one embodiment," "some embodiments," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0086] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for graded support construction of surrounding rock in deep coal mine roadways, characterized in that, Includes the following steps: Conduct geological surveys and surface explorations of the area to be excavated to determine the distribution of jointed strata within the area to be excavated. Based on the distribution location of the jointed strata, advance exploration is conducted in the area to be excavated to obtain the rock mass of the area to be excavated and to determine the geological characteristics and structural integrity characteristics of the rock mass; Based on the geological characteristics and structural integrity of the rock mass, the surrounding rock grade of the tunnel is determined, and the surrounding rock grade of the tunnel includes multiple levels; Based on the pre-defined mapping relationship between the support scheme and the surrounding rock grade of the roadway, a support scheme matching the surrounding rock grade of the roadway is determined, and support operations are carried out on the deep coal mine roadway after excavation. Displacement monitoring is conducted on the surrounding rock of the supported roadway until the displacement of the supported roadway surrounding rock converges, at which point the support is considered complete.

2. The method for graded support construction of surrounding rock in deep coal mine roadways according to claim 1, characterized in that, The steps for determining the surrounding rock grade of the tunnel based on the geological characteristics and structural integrity of the rock mass include: Based on the geological characteristics and structural integrity characteristics of the rock mass, calculate the basic quality indicators of the rock mass; Based on the basic quality indicators of the rock mass and the preset mapping table between the roadway surrounding rock grade and the basic quality indicators, the roadway surrounding rock grade corresponding to the rock mass is matched and determined. The roadway surrounding rock grade includes Grade I, Grade II, Grade III, Grade IV and Grade V surrounding rock, and the stability of the surrounding rock corresponding to Grade I, Grade II, Grade III, Grade IV and Grade V surrounding rock decreases in that order.

3. The method for graded support construction of surrounding rock in deep coal mine roadways according to claim 2, characterized in that, The geological characteristics of the primary surrounding rock are hard rock, with undeveloped joints, no weak surfaces, and the layered rock strata are very thick or very thick. The structural integrity characteristics are a massive monolithic structure, and the basic quality index is greater than 550. The geological characteristics of the secondary surrounding rock are hard rock or hard rock interspersed with soft rock, containing 1 to 2 sets of relatively well-developed joints, the layered rock strata are medium to thick or thick, the structural integrity characteristics are rubble-like crushed structure, and the basic quality index is greater than or equal to 451 and less than or equal to 550. The geological characteristics of the third-level surrounding rock are soft rock, containing 1 to 3 sets of relatively well-developed joints, with the layered soft surface destroyed, and the structural integrity characteristics are fragmented mosaic structure, with basic quality index greater than or equal to 351 and less than or equal to 450. The geological characteristics of the fourth-level surrounding rock are soft rock, containing 2 to 3 sets of developed joints, with a fragmented mosaic structure and a basic quality index greater than or equal to 251 and less than or equal to 350. The geological characteristics of the fifth-grade surrounding rock are one of the following: broken relatively soft rock, broken soft rock, extremely soft rock, and extremely broken rock. The structural integrity characteristics are brecciated and loose structure, and the basic quality index is less than or equal to 250.

4. The method for graded support construction of surrounding rock in deep coal mine roadways according to claim 3, characterized in that, The support scheme includes a primary support scheme, a secondary support scheme, a tertiary support scheme, and a quaternary support scheme. The primary support scheme is matched with the primary and secondary surrounding rock. The secondary, tertiary, and quaternary support schemes correspond to the surrounding rock grades of the roadway as tertiary, quaternary, and quaternary, respectively.

5. The method for graded support construction of surrounding rock in deep coal mine roadways according to claim 4, characterized in that, The primary support scheme includes the following steps: Multiple anchor bolt groups are installed at intervals on the surrounding rock of the roadway after excavation, in a direction away from the excavation face. The row spacing between two adjacent anchor bolt groups is 800 to 1000 mm, the spacing between two adjacent anchor bolts in each anchor bolt group is set to 800 mm, and each anchor bolt group contains 14 to 18 anchor bolts. Multiple solid anchor cable groups are installed on the surrounding rock of the roadway where the anchor bolt groups are laid, in a direction away from the excavation face. The spacing between two adjacent solid anchor cable groups is set to 1600 to 2000 mm, and the multiple solid anchor cable groups are arranged in a 7-0-7 pattern. After the solid anchor cable group support is completed, a layer of shotcrete is sprayed within a range of 30m behind the tunneling face to seal the surrounding rock. The thickness of the concrete layer is set to 100±10mm.

6. The method for graded support construction of surrounding rock in deep coal mine roadways according to claim 5, characterized in that, The secondary support scheme further includes the following steps in addition to the primary support scheme: Multiple high-pressure grouting anchor cable groups are installed on the surrounding rock of the roadway after the sprayed concrete layer, within a range of 30 to 50 meters behind the excavation face. The spacing between two adjacent high-pressure grouting anchor cable groups is set to 1600±200mm, and the multiple high-pressure grouting anchor cable groups are arranged in a 6-0-6 pattern.

7. The method for graded support construction of surrounding rock in deep coal mine roadways according to claim 6, characterized in that, The grouting material in the high-pressure grouting anchor cable assembly is a nano-modified composite single-liquid grouting material with a particle size D95 < 10 μm.

8. The method for graded support construction of surrounding rock in deep coal mine roadways according to claim 4, characterized in that, The three-level support scheme includes the following steps: Multiple solid anchor cable groups are installed at intervals on the surrounding rock of the roadway after excavation, in a direction away from the excavation face. The row spacing between two adjacent solid anchor cable groups is 800mm, and the spacing between two adjacent solid anchor cables in each solid anchor cable group is set to 800mm. After the solid anchor cable group support is completed, a layer of shotcrete is sprayed within a range of no more than 30m of the delayed tunneling face to seal the surrounding rock. The thickness of the concrete layer is set to 100±10mm. Multiple high-pressure grouting anchor cable groups are installed on the surrounding rock of the roadway after the sprayed concrete layer, within a range of 30 to 50 meters behind the excavation face. The spacing between two adjacent high-pressure grouting anchor cable groups is set to 1600±200mm, and the multiple high-pressure grouting anchor cable groups are arranged in a 7-0-7 pattern.

9. The method for graded support construction of surrounding rock in deep coal mine roadways according to claim 4, characterized in that, The fourth-level support scheme also includes the following steps: Multiple grouting holes are installed at the tunneling face, with a depth of 10±1 meters and a grouting pressure of less than or equal to 20MPa. Grouting reinforcement is carried out on the sidewall of the roadway in the form of alternating deep holes and shallow holes. The depth of the deep holes is set to 8000±1000mm, the depth of the shallow holes is set to 4000±1000mm, and the grouting pressure is set to 5 to 8MPa. After the grouting reinforcement is completed, multiple solid anchor cable groups are installed at intervals on the surrounding rock of the roadway after excavation, in the direction away from the excavation face. The row spacing between two adjacent solid anchor cable groups is 800mm, and the spacing between two adjacent solid anchor cables in each solid anchor cable group is set to 800mm. After the solid anchor cable group support is completed, a layer of shotcrete is sprayed within a range of 30m behind the tunneling face to seal the surrounding rock. The thickness of the concrete layer is set to 100±10mm. Multiple high-pressure grouting anchor cable groups are installed on the surrounding rock of the roadway after the sprayed concrete layer, within a range of 30 to 50 meters behind the excavation face. The spacing between two adjacent high-pressure grouting anchor cable groups is set to 1600±200mm, and the multiple high-pressure grouting anchor cable groups are arranged in a 7-0-7 pattern.

10. The method for graded support construction of surrounding rock in deep coal mine roadways according to claim 1, characterized in that, The method for graded support construction of surrounding rock in deep coal mine roadways also includes the following steps: Before tunnel excavation begins, the area to be excavated is pre-grouted and reinforced according to the distribution of jointed strata.

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