Punching method for rapid rock breaking tunneling of hard rock roadway

Abstract

The invention discloses a drilling method for rapid rock breaking tunneling of a hard rock roadway, and belongs to the field of mine roadway tunneling. The problem that existing hard rock roadway tunneling efficiency is low is solved. According to the technical scheme, the method comprises the following steps that S1, the section of the hard rock roadway is divided into a center operation area and a plurality of expanded tunneling operation areas, S2, a first expansion cracking area and second expansion cracking areas distributed on the periphery of the first expansion cracking area are arranged in the center operation area, a plurality of second main expansion cracking holes and a plurality of second auxiliary drilling holes are drilled in the second expansion cracking areas, and a plurality of second main expansion cracking holes and a plurality of second auxiliary drilling holes are drilled in the second expansion cracking areas; secondly, rock breaking equipment is adopted for simultaneously expanding and cracking a plurality of first expanding and cracking holes in the first expanding and cracking area, and then second main expanding and cracking holes in the second expanding and cracking area are sequentially expanded and cracked from top to bottom and from the center to the periphery; then crushing and expanding the tunneling operation area in sequence from top to bottom and from left to right; the method is applied to hard rock roadway tunneling.

Description

Technical Field

[0001] The invention provides a drilling method for fast rock breaking and excavation in a hard rock tunnel, belonging to the technical field of mine tunnel excavation. Background Art

[0002] In recent years, with the continuous advancement of coal mining, the resources of shallow, near-horizontal and gently inclined coal seams that are easy to mine in the mining area have become increasingly depleted. Mining operations have gradually shifted to deep coal seams, and the problem of slow rock tunnel excavation speed has become increasingly prominent. In actual construction, it was found that even if the rock formation is stable, due to its hard texture, the excavation efficiency is always difficult to improve. The excavation efficiency directly restricts the progress of mine development, which in turn affects the overall mining efficiency. This problem is mainly manifested in two aspects: First, the rock hardness of some all-rock tunnels is extremely high. The all-rock tunnel boring machines currently on the market are mostly suitable for medium and low hardness rocks. In actual operations, it is often difficult to achieve theoretical performance indicators; second, the comprehensive excavation equipment forms the tunnel contour by cutting and rubbing the rock wall, and gradually advances forward. When the comprehensive excavation equipment faces high-hardness and high-wear-resistant rock formations, the equipment's excavation efficiency drops significantly, the wear of the cutting components increases, and the loss of the entire machine increases significantly.

[0003] Currently, the technical approaches to increasing hard rock tunneling speeds primarily focus on equipment enhancement and pre-splitting rock breaking. Common measures for equipment enhancement include improving the material and structure of cutter teeth and adopting percussive tunneling techniques. Pre-splitting rock breaking methods include hydraulic fracturing, microwave irradiation, and blasting. However, due to factors such as construction costs, limited working space, and safety regulations, the widespread application of these technologies in some coal mines faces numerous obstacles. Summary of the Invention

[0004] In order to solve the technical problem of low excavation efficiency in existing hard rock tunnels, the present invention proposes a drilling method for rapid rock breaking and excavation in hard rock tunnels.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: a drilling method for rapid rock breaking and excavation in a hard rock tunnel, comprising the following steps:

[0006] Step S1: Divide the free section of the hard rock roadway into several operating areas, namely a central operating area and multiple expanded excavation operating areas, wherein the multiple expanded excavation operating areas are distributed around the central operating area;

[0007] Step S2: Arrange a first fracturing zone of a regular polygon and second fracturing zones distributed around the first fracturing zone in the central operating area, drill a first main fracturing hole at the center point and each vertex in the first fracturing zone, and evenly open a plurality of first auxiliary drilling holes in the first fracturing zone; drill a plurality of second main fracturing holes and a plurality of second auxiliary drilling holes in the second fracturing zone, the plurality of second main fracturing holes are distributed in an array in the geometric regularity of a regular triangle, and the plurality of second auxiliary drilling holes are distributed on a preset fracturing extension path of the second fracturing zone and at the edge of the second fracturing zone; after arranging the first main fracturing holes and the second main fracturing holes, use rock breaking equipment to simultaneously fracture the plurality of first main fracturing holes in the first fracturing zone, and then fracture the second main fracturing holes in the second fracturing zone in sequence from top to bottom and from the center to the surrounding areas;

[0008] Step S3: arrange a fourth fracturing zone in each of the multiple expanded excavation work areas, arrange a third fracturing zone in the shape of a regular polygon at the center of at least two fourth fracturing zones, drill a third main fracturing hole at the center point and each vertex of the third fracturing zone, and evenly open multiple third auxiliary drilling holes in the third fracturing zone; open multiple fourth main fracturing holes distributed in a regular array of regular triangles in the fourth fracturing zone, and evenly open multiple fourth auxiliary drilling holes at the edge of the fourth fracturing zone; after arranging the third auxiliary drilling holes and the fourth auxiliary drilling holes, break up multiple expanded excavation work areas in sequence from top to bottom and from left to right.

[0009] Furthermore, the first fracturing zone is a regular pentagon, and five first auxiliary drilling holes are opened. The five first auxiliary drilling holes are distributed in five regular triangle areas formed by connecting the center point of the first fracturing zone and each vertex.

[0010] Furthermore, when breaking the second fracture zone, the equilateral triangle area directly below the first fracture zone is fractured first, and the second main fracture holes located directly below the equilateral triangle area are gradually fractured downward until the lower edge of the second fracture zone. Then, all the second main fracture holes at the lower edge of the second fracture zone are linearly fractured in a continuous manner, and then the remaining second main fracture holes are fractured upward layer by layer in a continuous manner.

[0011] Furthermore, in step S2, when the second main expansion holes are arranged at a preset interval, if the second main expansion holes to be arranged will exceed the edge of the second expansion zone, a second auxiliary drilling hole is arranged at the edge of the second expansion zone so that the length of the crack of the second auxiliary drilling hole does not exceed the second expansion zone.

[0012] Furthermore, when crushing and expanding the excavation operation area in step S3, the third fracturing zone is crushed first, and then the fourth main fracturing hole in the triangular area near the lower part of the fourth fracturing zone near the third fracturing zone is crushed, and then the fourth main fracturing hole is crushed in a continuous and uninterrupted manner in the direction of the geometric center line of the free section of the hard rock tunnel, and then the fourth main fracturing hole is crushed layer by layer upward, and finally the fourth main fracturing hole at the edge of the fourth fracturing zone is crushed along the contour of the fourth fracturing zone, forming a surrounding crushing method.

[0013] Furthermore, two third fracturing zones are arranged in step S3, and the two third fracturing zones are respectively located at the central concentrated crushing points of the corresponding two fourth fracturing zones. The two expanded excavation working areas corresponding to the two fourth fracturing zones are both located above the central working area, and the remaining expanded excavation working areas are located below the central working area and no third fracturing zones are arranged.

[0014] Furthermore, the third rupture zone is a regular pentagon or a regular triangle.

[0015] Furthermore, in step S3, before crushing the next operating area, the distance between each two main expansion holes arranged in the next operating area is dynamically adjusted.

[0016] Furthermore, high-pressure water is injected into the first fracturing zone to assist the rock breaking equipment in breaking the rock mass in the first fracturing zone.

[0017] Furthermore, the first fracturing zone is provided with a plurality of water injection holes, and the second fracturing zone is provided with a plurality of drainage holes, and the water injection holes and the drainage holes cooperate with each other.

[0018] The present invention has the following beneficial effects compared to the prior art:

[0019] 1. The present invention divides the free section of a hard rock roadway into a central operating area and several expanded excavation operating areas, with the multiple expanded excavation operating areas distributed around the central operating area. The method of drilling first and then fracturing is adopted to gradually and layer by layer crush the rock mass of the free section of the hard rock roadway in the order of top to bottom and from the center to the surrounding areas. This method can achieve efficient crushing of rock mass with a surrounding rock strength coefficient f ≥ 8.

[0020] 2. The drilling method for rapid rock breaking and excavation in a hard rock tunnel of the present invention simultaneously fractures all first fracture holes in the first fracture zone when crushing the rock mass in the central working area. When crushing multiple expanded excavation working areas, they are crushed one by one in a sequence from top to bottom and from the center to the surrounding areas. This facilitates management and construction, effectively preventing the upper working area from losing its support force and falling into the air after the lower working area is crushed, thereby exacerbating dust diffusion. It also prevents the upper working area from collapsing after the crushing of the lower working area, thereby increasing the excavation workload in the lower working area, thereby improving excavation efficiency.

[0021] 3. The present invention can effectively increase the rock mass expansion and crack development rate and effectively guide the development direction of cracks after the main expansion hole is opened by drilling auxiliary holes in the working area, thereby promoting the development of rock mass cracks in a preset direction, so that the hard rock roadway can achieve an ideal crushing state.

[0022] 4. The present invention adopts the form of injecting high-pressure water into the first fracturing zone to assist the rock breaking equipment in breaking the rock mass in the first fracturing zone, which can effectively reduce the tensile strength of the rock mass and further improve the crushing efficiency of the first fracturing zone. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The present invention will be further described below with reference to the accompanying drawings:

[0024] Figure 1 The hole position distribution diagram in each working area when the surrounding rock strength coefficient f of the arched free section of the hard rock tunnel of the present invention is within the range of 10-12;

[0025] Figure 2 This is a distribution diagram of hole positions in each working area when the surrounding rock strength coefficient f of the arched free section of the hard rock tunnel of the present invention is in the range of 8 to 10;

[0026] Figure 3 The pore distribution of the first expansion zone of the present invention is Figure 1 ;

[0027] Figure 4 This is a hole position distribution diagram when the third expansion and rupture zone of the present invention is an equilateral triangle;

[0028] Figure 5 Schematic diagram of the positional relationship between the first main fracturing hole and the first auxiliary drilling hole in the first fracturing zone of the present invention Figure 1 ;

[0029] Figure 6 The pore distribution of the first expansion zone of the present invention is Figure 2 ;

[0030] Figure 7 Schematic diagram of the positional relationship between the first main fracturing hole and the first auxiliary drilling hole in the first fracturing zone of the present invention Figure 2 ;

[0031] Figure 8 This is a schematic diagram of the free cross-section structure of the hard rock tunnel behind the working area of the crushing center of the present invention;

[0032] Figure 9 This is a schematic diagram of the free cross-section structure of a hard rock tunnel after the crushing center working area and an expanded excavation operation area of the present invention;

[0033] Figure 10 This is a schematic diagram of the free cross-section structure of the hard rock tunnel after the crushing center working area and two expanded excavation operation areas of the present invention;

[0034] Figure 11 This is a schematic diagram of the free cross-section structure of the hard rock tunnel after the crushing center working area and three expanded excavation operation areas of the present invention;

[0035] Figure 12 It is a workflow diagram of the present invention;

[0036] In the figure: 1 is the area dividing line, 2 is the first fracturing zone, 3 is the first main fracturing hole, 4 is the second fracturing zone, 5 is the second main fracturing hole, 6 is the second auxiliary drilling hole, 7 is the third fracturing zone, 8 is the third main fracturing hole, 9 is the third auxiliary drilling hole, 10 is the fourth fracturing zone, 11 is the fourth main fracturing hole, 12 is the fourth auxiliary drilling hole, 13 is the hard rock tunnel, 14 is the water injection hole, 15 is the drainage hole, 16 is the central working area, 17 is the expanded excavation working area, 18 is the fissure, and 19 is the first auxiliary drilling hole. DETAILED DESCRIPTION

[0037] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate relative positions or positional relationships, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second" and the like are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, features defined as "first", "second" and the like may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0038] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0039] First, the meanings of some terms appearing in this technical solution are clarified:

[0040] Over-break and under-break: It is a technical term used in engineering. It takes the designed excavation contour line as the benchmark. The part of the actual excavated section outside the baseline is called over-break, and the part inside the baseline is called under-break.

[0041] Irregular lithology: a geological term that refers to the phenomenon that the composition, structure or spatial distribution of rocks show heterogeneous, discontinuous or sudden changes.

[0042] like Figures 1 to 12 As shown, the present invention provides a drilling method for rapid rock breaking and excavation in a hard rock tunnel, comprising the following steps:

[0043] Step S1: Divide the free section of the hard rock tunnel 13 into several working areas, namely a central working area 16 and a plurality of expanded excavation working areas 17, wherein the plurality of expanded excavation working areas 17 are distributed around the central working area 16. Figure 1 The area distribution is divided by the dividing line 1.

[0044] Currently, the free cross-section of the hard rock tunnel 13 is mostly arched or trapezoidal. Based on the shape of the free cross-section, the free cross-section is divided into five areas according to the different stress distribution conditions. Specifically, the free cross-section of the hard rock tunnel 13 is divided into a rectangular central operating area 16 and four irregular expanded excavation operating areas 17 distributed around the central operating area 16. The four expanded excavation operating areas 17 are the first expanded excavation area, the second expanded excavation area, the third expanded excavation area, and the fourth expanded excavation area. The first expanded excavation area and the second expanded excavation area are located above the central operating area 16, and the third expanded excavation area and the fourth expanded excavation area are located below the central operating area 16. Among them, the area of the central operating area 16 should meet the following requirements:

[0045] ;

[0046] Wherein, s is the area of the free section of the hard rock tunnel 13, and s1 is the area of the central working area 16.

[0047] Step S2: Arrange a first regular polygonal fracturing zone 2 and second fracturing zones 4 distributed around the first fracturing zone 2 in the central operating area 16. The first and second fracturing zones 2 and 4 cover the entire central operating area 16, i.e., the second fracturing zone 4 is the area of the central operating area 16 excluding the first fracturing zone 2, and the first fracturing zone 2 is a stress concentration zone. First primary fracturing holes 3 are drilled at the center point and vertices of the first fracturing zone 2, and multiple first auxiliary drilling holes 19 are evenly distributed within the first fracturing zone 2. Multiple second primary fracturing holes 5 and multiple second auxiliary drilling holes 6 are drilled within the second fracturing zone 4. The multiple second primary fracturing holes 5 are neatly arranged in the geometric pattern of a regular triangle, forming an orderly array structure. Multiple second auxiliary drilling holes 6 are distributed along the predetermined fracturing propagation path of the second fracturing zone 4 and at the edges of the second fracturing zone 4. After the first main fracturing holes 3 and the second main fracturing holes 5 are laid out, rock breaking equipment is used to simultaneously fracture multiple first main fracturing holes 3 in the first fracturing zone 2, and then rock breaking equipment is used to sequentially fracture the second main fracturing holes 5 in the second fracturing zone 4 in order from top to bottom and from the center to the surrounding areas.

[0048] Before operating step S2, you need to perform the following operations:

[0049] 1. A model of the hard rock roadway 13 to be crushed is established based on various parameters of the hard rock roadway 13, and the rock mass fracture length value is obtained through simulation experiments. The rock mass fracture length value includes the rock mass fracture length value during single-hole crushing and the rock mass fracture length value of each operating area after completing the crushing process of the previous operating area.

[0050] Specifically, after completing rock sampling on site of the hard rock tunnel 13 to be crushed, the samples were brought back to the laboratory, where uniaxial compression (UCS) tests and Brazilian splitting tests were carried out respectively to obtain key parameters of the rock tunnel, including tensile strength, compressive strength, Poisson's ratio, elastic modulus and surrounding rock strength coefficient. Based on the key parameters obtained above, a model of the hard rock tunnel 13 was constructed using simulation software to simulate the crushing operation of the hard rock tunnel 13, and obtain the stress distribution of the hard rock tunnel 13 before crushing. In the excavation project, after each operating area was crushed, the simulated stress distribution, simulated tensile strength, simulated compressive strength of the remaining operating areas were obtained, as well as the length of the rock cracks formed when a single hole was drilled and fractured in each operating area under different stress states.

[0051] 2. Based on the performance parameters of the rock breaking equipment, determine the diameter of the main fracturing hole, the diameter of the auxiliary drilling hole, the depth of the main fracturing hole and the auxiliary drilling hole, and the theoretical spacing between the main fracturing holes in each operating area. The diameter of the main fracturing hole and the diameter of the auxiliary drilling hole must meet the following requirements: ;

[0052] Where r0 is the diameter of the main expansion hole, and r1 is the diameter of the auxiliary drilling hole.

[0053] Since the smaller the diameter of the drilled hole, the shorter the drilling time of the rock breaking equipment, and no subsequent expansion-assisted drilling hole is required, the drilling efficiency is highest when the radius of the auxiliary drilling hole is half the radius of the main expansion hole.

[0054] In this embodiment, the rock breaking equipment adopts a combination of equipment commonly used in hard rock excavation, namely, a ZDY4500LPS type crawler impact drill or a pneumatic impact drill for coal mines and a hydraulic rock splitter with a hole diameter of 110 mm or a hole-type hydraulic expander. The hydraulic rock splitter can use six splitting rods for cracking at the same time, so that high pressure can be applied simultaneously at different positions in an operating area to form multiple concentrated stress points through hydraulic expansion force. These stress points interact with each other in a small range, significantly reducing the tensile strength of the rock mass, thereby more efficiently inducing the expansion of rock cracks 18.

[0055] The spacing between the two main fracturing holes in each operating area is determined based on the rock fracture length value obtained from the simulation experiment and the splitting force generated by the hydraulic rock splitter theory. The formula is:

[0056] ;

[0057] Where, L is the theoretical distance between the two main expansion holes, R t is the length of the rock mass crack, q is the theoretical splitting force generated by the hydraulic rock splitter, in MPa. The theoretical splitting force generated by the hydraulic rock splitter is generally obtained from the performance parameter table of the hydraulic rock splitter provided by the merchant, σ t It is the simulated tensile strength, the unit is MPa, and r0 is the pore size of the main expansion hole.

[0058] Specifically, the first fracturing zone 2 is a regular pentagon. Main fracturing holes are drilled at the center point and each vertex of the first fracturing zone 2. The main fracturing hole of the first fracturing zone 2 is called the first main fracturing hole 3. Five auxiliary drilling holes are evenly opened in the first fracturing zone 2. The auxiliary drilling holes drilled in the first fracturing zone 2 are called first auxiliary drilling holes 19. The five first auxiliary drilling holes 19 are distributed in the five equilateral triangle areas formed by connecting the center point and each vertex of the first fracturing zone 2. A hydraulic rock splitter is used to fracture the six main fracturing holes in the first fracturing zone 2. More specifically, the distance L from each vertex to the center of the first fracturing zone 2 is 11 Satisfy L1 / 2≤L 11 ≤L1, the distance L between the auxiliary drilling hole in the first fracturing zone 2 and the main fracturing holes distributed around it 12 Satisfy 0<L 12 <L1, the theoretical distance between any two first main expansion holes 3 and the theoretical distance between any two second main expansion holes 5 are both L1.

[0059] When fracturing the first main fracturing holes 3 of the first fracturing zone 2, the six splitting rods of the hydraulic rock splitter are used to simultaneously fracture the six first main fracturing holes 3 of the first fracturing zone 2, thereby applying pressure to the center of the first fracturing zone 2 from five angles at the same time. Under the action of the first auxiliary drilling hole 19, it helps to control the cracks generated during rock fracturing to develop in a preset direction, effectively reducing the strength of the rock mass. The first fracturing zone 2 adopts a regular pentagonal structure because the distance from the midpoint of the regular pentagon to each vertex is the same and the lines connecting the midpoint of the regular pentagon to the vertices are symmetrical. This increases the density of the first main fracturing holes 3 and can meet the fracture requirements of hard rock tunnels 13 with a surrounding rock strength coefficient f within the range of 10 to 12. Rocks with a surrounding rock strength coefficient f within the range of 10 to 12 include dense granite, limestone, quartz veins, and solid conglomerate.

[0060] The main fracturing holes drilled in the second fracturing zone 4 are called second main fracturing holes 5. Multiple second main fracturing holes 5 are neatly arranged in the geometric pattern of an equilateral triangle, forming an orderly array structure. The auxiliary drilling holes drilled in the second fracturing zone 4 are called second auxiliary drilling holes 6. Multiple second auxiliary drilling holes 6 are linearly distributed and located at the geometric centerline below the center point of the second fracturing zone 4 and at the edge of the second fracturing zone 4. The second main fracturing holes 5 are continuously and uninterruptedly fractured in sequence using a layered fracture method. Furthermore, the multiple second auxiliary drilling holes 6 are linearly distributed downward from the equilateral triangle area surrounded by the main fracturing holes near the bottom of the first fracturing zone 2. When fracturing the second fracturing zone 4, the equilateral triangle area directly below the first fracturing zone 2 is fractured first, and the second main fracturing holes 5 directly below this equilateral triangle area are fractured downward step by step until the lower edge of the second fracturing zone 4. Then, all second main fracturing holes 5 at the lower edge of the second fracturing zone 4 are fractured linearly in a continuous manner, and then the remaining second main fracturing holes 5 are fractured upward step by step in a continuous manner.

[0061] The second auxiliary drilling hole 6 is arranged at the geometric center line below the center point of the second fracturing zone 4 in order to reduce the crushing time of the second fracturing zone 4 under the action of the void effect after the first fracturing zone 2 is broken. The second auxiliary drilling hole 6 is not arranged on both sides of the geometric center line below the center point of the second fracturing zone 4 because after the equilateral triangle area directly below the first fracturing zone 2 in the second fracturing zone 4 and the second main fracturing hole 5 located directly below the equilateral triangle area are crushed, a deformation space is formed in the rock structure between the bottom edge of the second fracturing zone 4 and the first fracturing zone 2, eliminating the pressure on the lower rock mass in the second fracturing zone 4, so that the predetermined crushing effect can be achieved without drilling the second auxiliary drilling hole 6, while further saving the drilling time.

[0062] When the second main expansion holes 5 are arranged at a preset spacing, if the second main expansion holes 5 to be arranged will exceed the edge of the second expansion zone 4, then a second auxiliary drilling hole 6 is arranged at the edge of the second expansion zone 4 so that the length of the crack 18 of the second auxiliary drilling hole 6 does not exceed the second expansion zone 4.

[0063] Step S3: Arrange a fourth fracturing zone 10 in each of the multiple expanded excavation work areas 17, and arrange a regular polygonal third fracturing zone 7 at the center of at least two fourth fracturing zones 10. The third fracturing zone 7 and the fourth fracturing zone 10 cover the entire corresponding expanded excavation work area 17. The expanded excavation work area 17 where the regular polygonal third fracturing zone 7 is arranged is located above the central work area 16.

[0064] A plurality of fourth main fracturing holes 11 are arranged in an array in the fourth fracturing zone 10. These holes are arranged in a regular triangle pattern, forming an orderly array structure. A plurality of fourth auxiliary drilling holes 12 are evenly distributed along the edges of the fourth fracturing zone 10. Third main fracturing holes 8 are drilled at the center and vertices of the third fracturing zone 7, and a plurality of third auxiliary drilling holes 9 are evenly distributed within the third fracturing zone 7. This effectively prevents over-excavation and under-excavation, reduces the number of fourth main fracturing holes 11 drilled, significantly shortens drilling time, and further improves the excavation efficiency of the hard rock tunnel 13.

[0065] When crushing multiple expanded excavation work areas 17, the order from top to bottom and from left to right is followed. This crushing order is helpful for management and construction. Secondly, it can effectively prevent the upper work area from losing its support force and falling into the air after the lower work area is crushed, thereby exacerbating the problem of dust diffusion. Thirdly, it can prevent the upper work area from collapsing after the lower work area is crushed, thereby increasing the excavation workload of the lower work area and improving the excavation efficiency. Fourthly, the rock mass of the lower work area is crushed last to ensure the flatness of the tunnel after the lower work area is crushed.

[0066] When crushing and expanding the excavation operation area 17, the third fracturing zone 7 is crushed first, followed by the fourth main fracturing hole 11 in the triangular area below the fourth fracturing zone 10 near the third fracturing zone 7. The fourth main fracturing hole 11 is then continuously and uninterruptedly fractured toward the geometric centerline of the free section of the hard rock roadway 13. The fourth main fracturing holes 11 are then fractured layer by layer upwards, and finally, along the contour of the fourth fracturing zone 10, the fourth main fracturing holes 11 at the edge of the fourth fracturing zone 10 are fractured, forming a circular fracture pattern. If the third fracturing zone 7 is not provided within the fourth fracturing zone 10, the fourth main fracturing hole 11 is fractured layer by layer from bottom to top in the triangular area near the central operation area 16.

[0067] In this embodiment, two third fracturing zones 7 are deployed, located at the central, concentrated crushing locations of the corresponding two fourth fracturing zones 10. The two corresponding expanded excavation operating areas 17 are both located above the central operating area 16. The remaining two expanded excavation operating areas 17 are located below the central operating area 16 and do not have third fracturing zones 7. This embodiment is suitable for situations where the expanded excavation operating area 17 below the central operating area 16 is relatively small and the fourth main fracturing hole 11 has a relatively large aperture. Whether to deploy third fracturing zones 7 can be determined by those skilled in the art based on limited testing and crushing experience. During crushing, the two expanded excavation operating areas 17 above the central operating area 16 are crushed first, followed by the two expanded excavation operating areas 17 below the central operating area 16. Before crushing the two expanded excavation operating areas 17 below the central operating area 16, crushing and support measures are performed on the two expanded excavation operating areas 17 above the central operating area 16.

[0068] In this embodiment, the third fracturing zone 7 is a regular pentagon or an equilateral triangle. When the third fracturing zone 7 is a regular pentagon, the structure of the third fracturing zone 7 is the same as that of the first fracturing zone 2. When the third fracturing zone 7 is an equilateral triangle, a third main fracturing hole 8 is opened at each of the three vertices and the midpoint of the equilateral triangle, and a third auxiliary drilling hole 9 is opened at the midpoint of the straight line connecting the two vertices of the equilateral triangle third fracturing zone 7 to guide the growth direction of cracks during the fracturing of the third fracturing zone 7 and reduce the hardness of the rock mass. The equilateral triangle-shaped third fracturing zone 7 is suitable for the fracture requirements of hard rock tunnels 13 with a surrounding rock strength coefficient f within the range of 8 to 10. Rocks with a surrounding rock strength coefficient f within the range of 8 to 10 include solid sandstone, limestone, marble, dolomite, pyrite, and weak granite.

[0069] The formula for determining the surrounding rock strength coefficient f of the hard rock tunnel 13 to be excavated is: , where δ c The ultimate compressive stress value when the rock mass is destroyed under compressive strength, i.e. uniaxial compression. The rock strength grade is determined according to the surrounding rock strength coefficient classification table.

[0070] Auxiliary drilling holes mainly play two roles: first, based on the principle of void effect, drilling multiple auxiliary drilling holes around the main expansion hole can effectively increase the expansion speed of the rock mass and the development of cracks 18; second, the auxiliary drilling holes can guide the development direction of cracks after the main expansion hole is expanded, prompting the rock cracks to develop in the preset direction and achieve an ideal crushing state.

[0071] After the rock mass in the current operating area is crushed, the stress distribution in the free section of the hard rock tunnel 13 changes. In order to improve the excavation efficiency of the hard rock tunnel 13, before crushing the rock mass in the next operating area, the stress field changes of the rock mass in the remaining operating area after crushing the rock mass in the current operating area can be re-simulated based on the hard rock tunnel 13 model, and the spacing between the two main expansion holes in the next operating area can be re-determined to achieve a hole spacing suitable for the current operation.

[0072] It should be noted that in actual crushing operations, due to the presence of irregular lithology and complex rock stability in the entire hard rock tunnel 13, the simulated distance between the two main expansion holes may deviate from the actual distance. t ≤L i ≤2R t (L i The actual distance between the two main expansion holes is dynamically adjusted within the range of (representing the actual distance between the two main expansion holes). Among them, the actual distance between the two main expansion holes is required to be L i ≥R t In order to prevent the cracks 18 generated by two splitting rods simultaneously cracking two adjacent main cracking holes from overlapping excessively and reducing the overall excavation speed, the actual spacing L between the two main cracking holes is required to be i ≤2R t This is to prevent the length of the fissure 18 generated when two adjacent main fracturing holes are actually fractured from not meeting the requirement of the rock mass fracture length value.

[0073] For a hard rock tunnel 13 with high hardness and poor water absorption, when crushing the rock mass in the first fracturing zone 2 of the central operating area 16, since the first fracturing zone 2 is a stress concentration zone, it is difficult to crush. Crushing the rock mass with relatively high hardness will increase the loss of the hydraulic rock splitter. The present invention provides another embodiment to further improve the excavation efficiency of the hard rock tunnel 13, that is, to assist the hydraulic rock splitter in crushing the rock mass by injecting high-pressure water into the operating area. Specifically, the two first auxiliary drilling holes 19 located at the upper part of the first fracturing zone 2 are replaced by water injection holes 14, and the radius r2 of the water injection hole 14 is (r0 is the diameter of the main fracture hole), and at the same time, multiple drainage holes 15 are drilled in the second fracture zone 4 near the first fracture zone 2. The radius r3 of the drainage hole 15 is The central axis of the drainage hole 15 forms an angle of 15° with the central axis of the first primary fracturing hole 3. The central axis of the first primary fracturing hole 3 is perpendicular to the free cross-section of the hard rock roadway 13. The drainage hole 15 and the water injection hole 14 cooperate to drain water injected into the water injection hole 14. In this embodiment, two drainage holes 15 are provided, located in the lower left and lower right corners of the first fracturing zone 2, respectively.

[0074] The diameter of the water injection hole 14 is designed to meet the requirements of commonly available high-pressure water injection equipment and to ensure rapid injection of high-pressure water into the water injection hole 14 within a short period of time, thereby weakening the rock hardness of the first fracturing zone 2, effectively reducing the tensile strength of the rock mass, and further improving the crushing efficiency of the first fracturing zone 2. The diameter of the drainage hole 15 is designed to allow the water injected into the first fracturing zone 2 to be discharged without affecting subsequent crushing operations. Persons skilled in the art may adjust the diameters of the water injection hole 14 and the drainage hole 15 appropriately based on the type of high-pressure water injection equipment used and the actual crushing environment of the hard rock tunnel 13.

[0075] Regarding the amount of water injected into the water injection holes 14, a simulation experiment can be carried out based on the model of the hard rock tunnel 13 to be broken to obtain the impact of injecting high-pressure water into the two water injection holes 14 before breaking the first fracturing zone 2, on the rock stress of the working area. After multiple simulation tests and analysis and comparison of multiple groups of experimental data, the optimal water injection amount that can reduce the tensile strength of the rock can be determined.

[0076] The reason for using a hydraulic rock splitter in conjunction with high-pressure water injection into the operating area to break the rock mass only in the first fracturing zone 2 is that the mechanism by which these two pressures act on the rock mass is complex. Once the range of action is too large, the overall stability of the rock mass can be easily destroyed. Therefore, in this embodiment, when conditions permit, advance support is implemented in the front hard rock tunnel 13 to improve the overall stability of the surrounding rock. High-pressure water is then injected into the operating area to assist in breaking the first fracturing zone 2. After the rock mass in the first fracturing zone 2 is broken, the water injected into the first fracturing zone 2 is drained through the drainage hole 15. Conventional hydraulic fracturing operations are then carried out, i.e., the main fracturing hole is fractured using a hydraulic rock splitter to fracture the rock mass in the operating area.

[0077] More specifically, when a hydraulic rock splitter is used in combination with high-pressure water injection into the working area to break the rock mass of the first fracturing zone 2, high-pressure water is first injected into the two water injection holes 14 to reduce the tensile strength of the rock in the working area and then allowed to stand for 1 to 2 minutes. Subsequently, a hydraulic rock splitter is used to fracture multiple first main fracturing holes 3 in sequence. When fractured, the order of top first and then bottom is followed, that is, the upper area of the first fracturing zone 2 is fractured first, so that the water injected into the water injection holes 14 can be discharged from the drainage holes 15, so as not to affect the excavation speed of the overall hard rock tunnel 13. After the injected high-pressure water is completely removed, the lower area of the first fracturing zone 2 is fractured.

[0078] Regarding the specific structure of the present invention, it should be noted that the connection relationship between the various component modules adopted in the present invention is definite and feasible. Except for those specifically described in the embodiments, the specific connection relationship can bring about corresponding technical effects and solve the technical problems raised by the present invention without relying on the execution of corresponding software programs. The components, modules, models of specific components appearing in the present invention, the connection methods between each other, and the conventional usage methods and expected technical effects brought about by the above-mentioned technical features, except for those specifically described, all belong to the disclosed contents in patents, journal articles, technical manuals, technical dictionaries, and textbooks that can be obtained by technical personnel in this field before the application date, or belong to the existing technologies such as conventional technology and common knowledge in this field. There is no need to elaborate, so that the technical solution provided in this case is clear, complete, and feasible, and the corresponding physical products can be reproduced or obtained based on this technical means.

[0079] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A drilling method for rapid rock breaking and excavation in hard rock tunnels, characterized in that: The following steps are involved: Step S1, dividing the free section of the hard rock tunnel (13) into a plurality of operating areas, namely a central operating area (16) and a plurality of expanded excavation operating areas (17), wherein the plurality of expanded excavation operating areas (17) are distributed around the central operating area (16); Step S2, arranging a first fracturing zone (2) in the shape of a regular polygon and second fracturing zones (4) distributed around the first fracturing zone (2) in the central working area (16), drilling a first main fracturing hole (3) at the center point and each vertex in the first fracturing zone (2), and evenly opening a plurality of first auxiliary drilling holes (19) in the first fracturing zone (2); drilling a plurality of second main fracturing holes (5) and a plurality of second auxiliary drilling holes (6) in the second fracturing zone (4), wherein the plurality of second main fracturing holes (5) are distributed in an array in the shape of a regular triangle, and the plurality of second auxiliary drilling holes (6) are distributed on a preset fracturing extension path of the second fracturing zone (4) and at the edge of the second fracturing zone (4); after arranging the first main fracturing holes (3) and the second main fracturing holes (5), using rock breaking equipment to simultaneously fracture the plurality of first main fracturing holes (3) in the first fracturing zone (2), and then fracture the second main fracturing holes (5) in the second fracturing zone (4) in sequence from top to bottom and from the center to the periphery; Step S3, respectively arranging a fourth fracturing zone (10) in a plurality of expanded excavation operation areas (17), arranging a third fracturing zone (7) in the shape of a regular polygon at the center of at least two fourth fracturing zones (10), drilling a third main fracturing hole (8) at the center point and each vertex of the third fracturing zone (7), and evenly opening a plurality of third auxiliary drilling holes (9) in the third fracturing zone (7); opening a plurality of fourth main fracturing holes (11) distributed in an array in the shape of a regular regular triangle in the fourth fracturing zone (10), and evenly opening a plurality of fourth auxiliary drilling holes (12) at the edge of the fourth fracturing zone (10); after arranging the third auxiliary drilling holes (9) and the fourth auxiliary drilling holes (12), the plurality of expanded excavation operation areas (17) are broken in sequence from top to bottom and from left to right.

2. A drilling method for rapid rock breaking and excavation in a hard rock tunnel according to claim 1, characterized in that: The first expansion and fracturing zone (2) is a regular pentagon, and five first auxiliary drilling holes (19) are opened. The five first auxiliary drilling holes (19) are distributed in five regular triangle areas formed by connecting the center point of the first expansion and fracturing zone (2) with each vertex.

3. The drilling method for rapid rock breaking and excavation in a hard rock tunnel according to claim 1, characterized in that: When the second fracture zone (4) is broken, the equilateral triangle area directly below the first fracture zone (2) is fractured first, and the second main fracture holes (5) located directly below the equilateral triangle area are fractured downward step by step until the lower edge of the second fracture zone (4), and then all the second main fracture holes (5) at the lower edge of the second fracture zone (4) are fractured linearly in a continuous manner, and then the remaining second main fracture holes (5) are fractured upward layer by layer in a continuous manner.

4. The drilling method for rapid rock breaking and excavation in a hard rock tunnel according to claim 1, characterized in that: In step S2, when the second main expansion holes (5) are arranged at a preset interval, if the second main expansion holes (5) to be arranged will exceed the edge of the second expansion zone (4), a second auxiliary drilling hole (6) is arranged at the edge of the second expansion zone (4) so that the length of the crack (18) of the second auxiliary drilling hole (6) does not exceed the second expansion zone (4).

5. The drilling method for rapid rock breaking and excavation in a hard rock tunnel according to claim 1, characterized in that: When crushing and expanding the excavation operation area (17) in step S3, the third fracturing zone (7) is crushed first, and then the fourth main fracturing hole (11) in the triangular area of the lower part of the fourth fracturing zone (10) adjacent to the third fracturing zone (7) is crushed, and then the fourth main fracturing hole (11) is crushed in a continuous and uninterrupted manner in the direction of the geometric center line of the free section of the hard rock tunnel (13), and then the fourth main fracturing hole (11) is crushed upward layer by layer, and finally the fourth main fracturing hole (11) at the edge of the fourth fracturing zone (10) is crushed along the outline of the fourth fracturing zone (10), forming a surrounding crushing method.

6. The drilling method for rapid rock breaking and excavation in a hard rock tunnel according to claim 1, characterized in that: In step S3, two third fracturing zones (7) are arranged. The two third fracturing zones (7) are respectively located at the central concentrated crushing locations of the corresponding two fourth fracturing zones (10). The two expanded excavation operation zones (17) corresponding to the two fourth fracturing zones (10) are both located above the central operation zone (16). The remaining expanded excavation operation zones (17) are located below the central operation zone (16) and are not arranged with the third fracturing zones (7).

7. The drilling method for rapid rock breaking and excavation in a hard rock tunnel according to claim 1, characterized in that: The third expansion and rupture zone (7) is a regular pentagon or a regular triangle.

8. The drilling method for rapid rock breaking and excavation in a hard rock tunnel according to claim 1, characterized in that: In step S3, before crushing the next operating area, the distance between the two main expansion holes arranged in the next operating area is dynamically adjusted.

9. The drilling method for rapid rock breaking and excavation in a hard rock tunnel according to claim 1, characterized in that: High-pressure water is injected into the first fracturing zone (2) to assist the rock breaking equipment in breaking the rock mass in the first fracturing zone (2).

10. The drilling method for rapid rock breaking and excavation in a hard rock tunnel according to claim 1, characterized in that: The first fracturing zone (2) is provided with a plurality of water injection holes (14), and the second fracturing zone (4) is provided with a plurality of drainage holes (15), and the water injection holes (14) and the drainage holes (15) cooperate with each other.

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