Deep-buried tunnel stress relief blasting method and device based on fracture surface reflection

Abstract

The invention discloses a deep-buried tunnel stress relieving blasting method and device based on fracture surface reflection, and relates to the technical field of deep-buried tunnel blasting excavation. The method comprises the steps that rock mass stress state parameters and rock strength related to a deep-buried tunnel face are obtained; according to the rock mass stress state parameters and the rock strength, multiple rows of outer side blast holes parallel to the large principal stress direction are formed in the outermost side of the tunnel face, and multiple rows of main blast holes are formed in the middle of the tunnel face; during blasting, the outer side blast hole is firstly detonated to form a fracture surface, and then the main blast hole is detonated; wherein the fracture surface is used for reflecting stress waves generated when the main blast hole is detonated. By adopting the method, the reflection of the stroke stress wave at the formed through fracture surface can be realized, so that the local damage and crushing of the rock mass at the fracture surface are realized, the local bearing capacity of the rock mass is obviously reduced, the local stress concentration degree of the rock mass is reduced, and the accumulated stress of the rock mass is efficiently released.

Description

Technical Field

[0001] The present invention relates to the technical field of deep-buried tunnel blasting excavation, and particularly to a stress relief blasting method and device for deep-buried tunnels based on fracture plane reflection. Background Art

[0002] In the construction of large deep-buried tunnel projects such as water conservancy and hydropower projects and mine projects, especially in tunnels with large-section blasting excavation, due to its intense blasting impact and in-situ stress unloading effect, extremely strong rock bursts usually occur during the tunnel construction process. In the related art, for high-risk areas of strong rock bursts, advance stress relief blasting is mostly used to release the high stress in advance, so that the normal blasting excavation footage of the tunnel is in the stress release area.

[0003] However, with the increasing depth of the tunnel, the in-situ stress borne by the surrounding rock will increase, which inhibits the length and width of the cracks generated by blasting, resulting in difficulty in crack penetration and opening between blast holes. Therefore, when excavating ultra-deep tunnels (greater than 1000m), there are two problems with stress relief blasting: one is that it is difficult for the cracks between stress relief blasting holes to penetrate each other; the other is that under the extrusion of high stress, the formed through crack surface by stress relief blasting will re-close and re-bear the stress. The above two problems will lead to a deterioration in the stress relief blasting effect of deep-buried tunnels, and even the possibility of ineffective stress relief blasting, making it difficult to meet the safety requirements of current deep-buried tunnel engineering blasting excavation. Summary of the Invention

[0004] Based on this, in view of the above technical problems, it is necessary to provide a stress relief blasting method and device for deep-buried tunnels based on fracture plane reflection that can increase the stress release effect of rock masses.

[0005] A stress relief blasting method for deep-buried tunnels based on fracture plane reflection includes:

[0006] Obtaining the rock mass stress state parameters and rock strength of the deep-buried tunnel heading face;

[0007] According to the rock mass stress state parameters and the rock strength, arranging multiple rows of outer blast holes at the outermost side of the heading face and arranging multiple rows of main blast holes in the middle of the heading face;

[0008] During blasting, first detonate the outer blast holes to form a fracture plane, and then detonate the main blast holes; wherein, the fracture plane is used to reflect the stress wave generated when the main blast holes are detonated.

[0009] In the above solution, the rock mass stress state parameters include the direction of the maximum principal stress; the outer blast holes and the main blast holes are arranged parallel to the direction of the maximum principal stress.

[0010] In the above solution, the rock mass stress state parameters further include the maximum principal stress magnitude; arranging multiple rows of outer blast holes at the outermost side of the heading face includes:

[0011] Determine the crack propagation length of the heading face under the current in-situ stress conditions according to the maximum principal stress magnitude and the rock strength;

[0012] Determine the number of blast holes in each row of outer blast holes according to the crack propagation length and the tunnel width parallel to the direction of the maximum principal stress.

[0013] In the above solution, the spacing between any two adjacent outer blast holes satisfies the spacing condition L ≤ 2l; where l is the crack propagation length.

[0014] In the above solution, the peak stress wave generated by the detonation of the main blast hole after attenuation by the row spacing reflects on the fracture surface to produce a stress wave peak greater than the rock tensile strength; the row spacing represents the distance between the outer blast hole and the main blast hole.

[0015] In the above solution, the blast hole depths of the outer blast holes and the main blast holes are arranged as a set multiple of the expected excavation footage.

[0016] In the above solution, the outer blast holes are arranged to incline at a set angle range towards the heading face.

[0017] In the above solution, the bottom charging lengths of the outer blast holes and the main blast holes are arranged within a set length range.

[0018] In the above solution, the outer blast holes and the main blast holes are detonated in a bottom initiation manner.

[0019] A deep-buried tunnel stress relief blasting device based on fracture surface reflection includes:

[0020] A parameter acquisition module for acquiring rock mass stress state parameters and rock strength regarding the heading face of a deep-buried tunnel;

[0021] A blast hole arrangement module for arranging multiple rows of outer blast holes at the outermost side of the heading face and multiple rows of main blast holes in the middle of the heading face according to the rock mass stress state parameters and the rock strength;

[0022] A detonation module for, during blasting, first detonating the outer blast holes to form a fracture surface, and then detonating the main blast holes; where the fracture surface is used to reflect the stress wave generated by the detonation of the main blast hole.

[0023] The above - mentioned stress relief blasting method and device for deep - buried tunnels based on fracture - plane reflection, according to the rock mass stress state parameters and rock strength of the working face of the deep - buried tunnel, arrange outer holes on the outermost side of the working face and main holes in the middle of the working face. During blasting, first detonate the outer holes to form a fracture plane, and then detonate the main holes, so as to form the reflection of stress waves at the formed through - fracture plane, realize the distributed damage and fragmentation of the rock mass at the fracture plane, cause a significant reduction in the local bearing capacity of the rock mass, thereby reducing the degree of local stress concentration in the rock mass, efficiently releasing the stress accumulated in the rock mass, and being beneficial to improving the stress relief blasting effect of deep - buried tunnels. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic flow chart of the stress relief blasting method for deep - buried tunnels based on fracture - plane reflection in an embodiment;

[0025] Figure 2 It is a schematic flow chart of determining the number of holes in each row of outer holes in an embodiment;

[0026] Figure 3 It is a plane design drawing of stress relief blasting in an embodiment;

[0027] Figure 4 It is a schematic axial charge structure diagram of stress relief blasting in an embodiment;

[0028] Figure 5 It is a schematic diagram of cracks after detonation of outer holes in an embodiment;

[0029] Figure 6 It is a schematic diagram of crack distribution and stress wave reflection after detonation of main holes in an embodiment;

[0030] Figure 7 It is a schematic diagram of a local fragmentation area in an embodiment;

[0031] Figure 8 [[ID=3 forty]]It is a schematic diagram of comparing the stress release effects of different stress relief blastings in an embodiment;

[0032] Figure 9 It is a structural block diagram of the stress relief blasting device for deep - buried tunnels based on fracture - plane reflection in an embodiment.

[0033] Reference numerals: 1 Stress relief blasting hole, 2 Blasting crack, 3 Fracture plane penetrated by the outermost holes, 4 Simplified through - fracture plane, 5 Tensile stress wave reflected at the through - fracture plane, 6 Local reflection tensile failure area at the fracture plane, 7 Tunnel excavation working face, 8 Stress relief blasting charge section. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0034] In order to make the objectives, technical solutions, and advantages of this application clearer and more understandable, the following further details this application in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not used to limit this application.

[0035] The following details the implementation details of the technical solutions of the embodiments of this application.

[0036] In one embodiment, as Figure 1 shown, a stress relief blasting method for deep-buried tunnels based on fracture surface reflection is provided, and this method may include the following steps:

[0037] Step S101, obtain the rock mass stress state parameters and rock strength of the heading face of the deep-buried tunnel.

[0038] A deep-buried tunnel refers to a tunnel buried at a relatively deep position underground, usually used in fields such as transportation (such as railways, highways), water conservancy projects (such as water pipelines), or mining. Due to its large burial depth, deep-buried tunnels face complex geological conditions and high ground stress, which makes the safety and efficiency during tunnel construction crucial issues.

[0039] During tunnel construction, the heading face refers to the surface of the rock mass in the front being excavated, which is directly exposed to the construction environment and bears the pressure and stress of the surrounding rock mass. The rock mass stress state of the heading face has an important impact on the stability of construction. Understanding the rock mass stress state is the basis for ensuring the safe excavation of the tunnel. The rock mass stress state describes the stress distribution within the rock mass, and these stresses are the result of the combined action of various factors such as surface loads, groundwater, and geological structures. Therefore, the design and construction of deep-buried tunnels must fully consider the heading face and its rock mass stress state to ensure the safety and smooth progress of the project.

[0040] Here, based on the previous geological exploration data, the rock mass stress state parameters and rock strength of the heading face of the deep-buried tunnel can be obtained to ensure the safety and effectiveness of tunnel construction. In practical applications, the rock mass stress state parameters may include the maximum stress direction and the maximum stress magnitude. Among them, the maximum stress direction refers to the acting direction of the maximum principal stress borne in the rock mass, which determines the failure mode and crack propagation direction of the rock mass and is an important design basis for the blasting scheme. The maximum stress magnitude refers to the value of the maximum principal stress borne in the rock mass, usually expressed in pascals (Pa) or megapascals (MPa), which directly affects the stability and bearing capacity of the rock mass. A higher stress magnitude may lead to the failure or collapse of the rock mass. Rock strength refers to the ability of the rock to resist failure under the action of external forces, mainly measured by compressive strength, tensile strength, and shear strength.

[0041] Step S102: According to the rock mass stress state parameters and rock strength, arrange multiple rows of outer blast holes on the outermost side of the heading face, and arrange multiple rows of main blast holes in the middle of the heading face.

[0042] When carrying out blasting operations for deep-buried tunnels, it is necessary to formulate a blast hole layout plan based on the obtained rock mass stress state parameters and rock strength, so as to utilize the stress state characteristics of the rock mass and optimize the blasting effect.

[0043] In practical applications, clean the excavation heading face, lay out the corresponding blast holes according to the blast hole layout plan matching the rock mass stress state parameters and rock strength, and then carry out drilling to prepare for charging and initiation. Among them, the stress relief blast holes here include outer blast holes and main blast holes. Specifically: arrange multiple rows of outer blast holes (such as 2 rows) in the outermost area of the heading face. The outer blast holes are mainly used to weaken the integrity of the rock mass edge, release the stress of the surrounding rock, and form initial cracks; arrange multiple rows of main blast holes (such as 2 - 3 rows) in the middle area of the heading face. These main blast holes are the main destructive forces for blasting, used to further break the rock mass and complete the excavation of the heading face.

[0044] It should be noted that the layout of the outer blast holes and the main blast holes matches the current rock mass stress state parameters and rock strength. Through scientific and reasonable blast hole layout, it is ensured that the rock mass stress can be effectively released, the destruction effect can be enhanced, and the construction efficiency can be improved. After drilling is completed, the hole layout accuracy can be further checked.

[0045] In practical applications, the blast hole layout plan involves the number, depth, and spacing of blast holes, etc. It should be optimized according to the rock mass stress state parameters and rock strength, so that the blast hole layout can match the current stress condition. The following will detail how to determine the blast hole layout according to the rock mass stress state parameters through different embodiments.

[0046] In one embodiment, the rock mass stress state parameters include the direction of the maximum principal stress. When arranging blast holes, the design of the outer blast holes and the main blast holes should be parallel to the direction of the maximum principal stress, that is, arrange multiple rows of outer blast holes parallel to the direction of the maximum principal stress on the outermost side of the heading face, and arrange multiple rows of main blast holes parallel to the direction of the maximum principal stress in the middle of the heading face.

[0047] Based on this, when the outer blast holes and the main blast holes are parallel to the direction of the maximum principal stress, the stress waves generated by blasting can effectively propagate along the direction of the maximum principal stress, thereby better releasing the stress of the surrounding rock, reducing the stress concentration of the rock mass, and reducing the risk of collapse. Secondly, the parallel arrangement of blast holes can utilize the characteristics of the direction of the maximum principal stress to form a more effective crack propagation path. In addition, the parallel arrangement can also better control the influence range of blasting, reduce the disturbance to the surrounding rock mass, and ensure the safety during the construction process.

[0048] In one embodiment, the rock mass stress state parameters further include the maximum principal stress magnitude and the rock layer strength. As Figure 2 shown, Figure 2 The flowchart shows the process of determining the number of blast holes in each row of outer blast holes, including the following steps:

[0049] Step S201: Determine the crack propagation length of the tunnel face under the current in-situ stress conditions based on the maximum principal stress magnitude and the rock layer strength.

[0050] The in-situ stress state refers to the stress distribution within the rock mass generated by the action of the earth's gravity, geological structure, rock self-weight, and other external factors (such as groundwater, earthquakes, etc.). Different in-situ stress states will affect the strength and deformation characteristics of the rock mass.

[0051] Under different in-situ stress conditions, the failure mode and crack propagation behavior of the rock mass will be different. Therefore, understanding the crack propagation length under the current in-situ stress conditions can more accurately predict the response of the rock mass under blasting or other external forces.

[0052] Based on the known principal stress magnitude and rock strength, by using numerical simulation (such as the finite element method), the behavior of the rock mass under the current in-situ stress conditions can be simulated. On this basis, by establishing a numerical model of the rock mass, applying the known principal stress magnitude, and observing the crack propagation, the crack propagation length l can be determined. In practical applications, the crack propagation length l can also be calculated by theoretical calculation (such as the fracture mechanics model) through formulas.

[0053] Step S202: Determine the number of blast holes in each row of outer blast holes based on the crack propagation length and the tunnel width parallel to the maximum principal stress direction.

[0054] The crack propagation length refers to the distance that the crack propagates from the outer blast hole to the surrounding area after the blasting of a single outer blast hole. This length reflects the effective range of the blasting effect and determines the area that the crack can cover. The layout of the outer blast holes needs to ensure that the cracks generated by the blasting can cover the entire tunnel width. Among them, the tunnel width refers to the actual width of the tunnel, usually the width in the direction of the maximum principal stress, and this parameter determines the area to be covered.

[0055] The crack propagation length generated by each outer blast hole after blasting is l. Since the crack propagation of each outer blast hole is outward, the effective coverage range of each outer blast hole is 2l (i.e., the total length of the crack propagating to both sides). Based on this, the number of blast holes in each row of outer blast holes is:

[0056]

[0057] where D represents the tunnel width parallel to the maximum principal stress direction.

[0058] In the above embodiments, by the crack propagation length, combined with the tunnel width and the direction of the maximum principal stress, the outer blast holes are reasonably arranged, which not only ensures that the blasting cracks cover the entire heading face, but also optimizes the number of outer blast holes, reduces unnecessary blasting costs, and improves the construction efficiency and safety at the same time.

[0059] In one embodiment, the crack propagation length also defines the spacing of the outer blast holes. The blast hole spacing refers to the distance between two adjacent outer blast holes. A reasonable spacing can ensure that the cracks generated by blasting can be effectively connected, thereby improving the fragmentation effect.

[0060] It can be understood that if the blast hole spacing is too large, it may cause some areas not to be effectively fragmented, which will reduce the blasting efficiency and may lead to rock mass collapse or other safety hazards during the construction process. Therefore, by controlling the blast hole spacing, it is ensured that the cracks can be effectively connected. Here, the blast hole spacing needs to meet the spacing condition L≤2l, which means that the spacing L between any two adjacent outer blast holes is less than or equal to 2l. When the spacing L between two adjacent outer blast holes is less than or equal to 2l, it means that the cracks generated by the two outer blast holes can be connected to each other to form a continuous crack network. This connection helps to improve the overall blasting effect and ensure that the rock mass is effectively fragmented. If the blast hole spacing L is greater than 2l, it may cause a gap between the cracks generated by the two outer blast holes, forming an unfragmented rock mass area.

[0061] In this embodiment, by reasonably controlling the spacing of the outer blast holes, the effective connection of the cracks can be ensured, the fragmentation efficiency of the rock mass can be improved, the construction risk can be reduced, and the construction safety can be ensured.

[0062] In one embodiment, there are also certain requirements for the distance (i.e., the row spacing) between the outer blast holes and the main blast holes. It can be understood that when the middle main blast hole explodes, strong stress waves will be generated. These stress waves are caused by the energy generated by the explosion and can propagate in the rock and cause stress changes. When the stress waves propagate in the rock, their intensity will decay with the increase of the propagation distance. This decay is caused by the dispersion of energy, the absorption of the rock, and other factors. If the set row spacing is too large, the energy of the stress waves generated by the main blast holes will be low, and thus the energy of the reflected stress waves generated by reflection through the fracture surface will also be low, which may not be able to overcome the tensile strength of the rock, resulting in the rock not being effectively fractured and the blasting effect being unsatisfactory. Based on this, the arranged row spacing needs to ensure that the intensity of the stress reflected waves generated by reflection through the fracture surface is greater than the tensile strength of the rock to ensure that the rock is effectively fractured.

[0063] Assume that the row spacing between the outer blast holes and the main blast holes is d. When the main blast holes explode, the stress wave generated will propagate to the fracture surface, and a stress reflection wave will be generated in the fracture surface. During this propagation process, the intensity of the stress wave will attenuate. The attenuation of the stress wave intensity is measured using the attenuation coefficient β, and the attenuation coefficient β describes the rate of attenuation of the stress wave intensity during propagation. Based on this, the peak value of the stress reflection wave can be expressed as:

[0064]

[0065] where, σ d represents the peak value of the stress reflection wave, P represents the peak value of the stress wave excited by the main blast holes, and R represents the radius of the main blast holes. In the above formula, the peak value of the stress reflection wave σ d is obtained through attenuation calculation of the peak value of the stress wave p, which reflects the relative attenuation of the stress wave during propagation.

[0066] The tensile strength of the rock σ t is the maximum stress that the rock can withstand in the tensile state. To cause the rock to fracture, the peak stress σ d after attenuation must be greater than or equal to the tensile strength of the rock σ t . Based on this, the row spacing condition can be expressed as:

[0067]

[0068] The significance of the above row spacing condition is to ensure that the row spacing d is small enough so that the stress wave still has sufficient intensity to overcome the tensile strength of the rock when it reaches the outermost blast holes, thereby achieving effective fracture.

[0069] In this embodiment, by calculating the attenuation of the stress wave during propagation, the row spacing D is designed reasonably to ensure the effectiveness and safety of blasting.

[0070] It should be noted that after determining the number of blast holes, row spacing, and spacing using the crack propagation length, a stress relief blasting plane design drawing can be drawn on computer-aided design software (such as CAD), as Figure 3 shown. In Figure 3 , the minimum principal stress direction and the maximum principal stress direction are shown. Among them, all stress relief blasting holes are arranged parallel to the maximum principal stress direction. In Figure 3 , the first row of blast holes and the fourth row of blast holes belong to the outer blast holes, and the second row of blast holes and the third row of blast holes belong to the main blast holes.

[0071] In one embodiment, in stress relief blasting, the design of the hole depth of the blast holes is an important factor in ensuring the blasting effect and the stability of the rock mass. Deeper blast holes can accommodate more explosives, thereby generating stronger explosion energy, which can enable stress waves to propagate farther in the rock and enhance the intensity of the stress waves. This helps to improve the overall blasting effect and ensure that the rock mass can be effectively broken.

[0072] Among them, the hole depths of the outer blast holes and the main blast holes are set according to the expected excavation footage. The excavation footage refers to the depth of the rock that can be effectively excavated in a single blasting or mechanical excavation operation. Currently, in the areas where deep-buried high-stress rock bursts occur, the blasting excavation footage is generally 1 - 2 m. The hole depth is set to 2 - 3 times the expected excavation footage, so as to ensure that during the blasting process, the energy of the explosives can be fully utilized to form effective crack propagation. Assuming the expected excavation footage is 2 m, then the hole depth is 4 - 6 m.

[0073] In practical applications, after determining the hole depth, layout the corresponding blast holes according to the stress relief blasting design shown in Figure 3 , and then drill holes so that the hole depth can match the expected excavation footage.

[0074] In one embodiment, in order to increase the stress release area, as shown in Figure 4 , Figure 4 shows the axial charge structure of stress relief blasting. The outer blast holes are arranged to incline towards the heading face within a set angle range (15 - 20°). The outwardly inclined blast holes can expand the stress release area, enabling the stress waves generated by the explosion to act more effectively on the surrounding rock and promoting the fracture and movement of the rock.

[0075] In one embodiment, it is necessary to charge the blast holes. Here, the bottom charge lengths of the outer blast holes and the main blast holes are arranged within a set length range (1 - 1.5 m). A charge length of 1 - 1.5 m can ensure that the explosion energy acts fully on the surrounding rock, promoting stress release and rock fracture. This set length range helps to form uniform stress waves, reduce stress concentration, and optimize the blasting effect. Among them, during the charging process, the initiating detonators of the blast holes are arranged at the bottom of the charge column, and the blast holes are blocked to prepare for subsequent initiation.

[0076] Step S103, during blasting, first initiate the outer blast holes to form a fracture surface, and then initiate the main blast holes.

[0077] In the blasting operation of tunnel excavation, the design of the blasting sequence is a key link in ensuring construction safety and the blasting effect.

[0078] First, detonate the outer holes arranged on the outermost side of the tunnel face. The purpose of this process is to form a continuous fracture surface to ensure that the rock mass can effectively release stress after blasting. The blasting of the outer holes will cause the initial damage of the rock mass, forming continuous cracks and fracture surfaces, as Figure 5 shown. The blasting of the outer holes will guide the cracks to expand along the predetermined direction, providing a crack path for the subsequent blasting of the main holes, reducing the overall strength of the rock mass, and providing a good foundation for the subsequent blasting of the main holes.

[0079] After the blasting of the outer holes is completed and the fracture surface is formed, detonate the main holes arranged in the middle of the tunnel face. The blasting of these main holes will utilize the fracture surface formed by the outer holes to further release the stress of the rock mass. Specifically, the stress wave generated by the explosion of the main holes is reflected at the continuous fracture surface, forming a reflected stress wave as shown in Figure 6 . Among them, the continuous fracture surface in Figure 6 is a simplified schematic diagram of the continuous fracture surface in Figure 5 . The tensile stress of the reflected stress wave will form a local fragmentation area as shown in Figure 7 near the fracture surface. This reflection effect can further enhance the damage effect at the fracture surface and increase the local fragmentation degree of the rock mass at the fracture surface. By forming a local reflected tensile failure area, the extrusion and closure degree of the high stress on the fracture surface can be reduced, so as to better release the stress accumulated in the rock mass and achieve the purpose of stress advance release

[0080] After the blasting operation is completed, use a blower to clean the outer holes, and then use a borehole TV to observe the fragmentation effect at the fracture surface to verify the stress relief effect. Among them, as shown in Figure 8 , Figure 8 shows a comparison schematic diagram of the stress release effects of different stress relief blasts. In Figure 8 , the horizontal axis represents the distance from the tunnel face outward, reflecting the spatial distribution of the in-situ stress, and the vertical axis represents the magnitude of the in-situ stress in the rock mass. The curve before stress relief blasting represents the original in-situ stress distribution in the rock mass before blasting, reflecting the stress state of the rock mass when no blasting is carried out. Among them, when approaching the tunnel face, the in-situ stress is higher, and as the distance increases, the in-situ stress gradually decreases. The curve after traditional stress relief blasting represents the in-situ stress distribution in the rock mass after using the traditional blasting method. It can be seen that the traditional blasting method has limited stress release effect and higher residual stress. The curve after the stress relief blasting in this embodiment shows that the stress relief blasting method provided in this embodiment can effectively reduce the stress concentration area, the in-situ stress is released more fully, and the residual stress is lower.

[0081] In practical applications, after cleaning the blasted rock mass, the tunnel can be excavated at a certain footage speed according to the design requirements and construction plan.

[0082] Based on this, detonating the outer blast holes first can effectively form a fracture surface, reduce the blasting energy required for the main blast holes, improve the overall blasting efficiency, provide a good damage path for the subsequent blasting of the main blast holes, make the blasting effect of the main blast holes more obvious, and ensure that the rock mass can be effectively blasted. Compared with the traditional stress relief blasting, this method can ensure that the cracks between the stress relief blasting holes are interconnected, increase the degree of local rock fragmentation, prevent the rock mass in the fragmented area from being squeezed and closed by high stress, resulting in a large amount of stress release, thus solving the problem of poor stress release caused by the squeezing and closing of the crack surface in traditional stress relief blasting, and does not require additional investment in construction personnel and equipment, ensuring the construction efficiency and improving the rock burst risk in the excavation of deep buried tunnels.

[0083] In one embodiment, the outer blast holes and the main blast holes are detonated in a bottom initiation manner. Bottom initiation means arranging the detonating detonator at the bottom of the blast hole to ensure that the explosive energy is released from the bottom upwards. This method can effectively utilize the energy of the explosive and promote the fracture and stress release of the rock.

[0084] In the above embodiment, through the rock mass stress state parameters of the tunnel face, multiple rows of outer blast holes are arranged on the outermost side of the tunnel face, and multiple rows of main blast holes are arranged in the middle of the tunnel face. During the blasting process, the outer blast holes are detonated first to form a through fracture surface, and then the main blast holes are detonated. By using the reflection effect of the stress wave on the formed fracture surface, local damage and fragmentation of the rock mass at the fracture surface are realized, thereby reducing the layout bearing capacity of the rock mass and realizing the efficient utilization of the explosion stress wave. This stress relief blasting method can ensure that the cracks between the stress relief blasting holes are interconnected, increase the degree of local rock fragmentation, prevent the rock mass in the fragmented area from being squeezed and closed by high stress, resulting in a large amount of stress release, thus solving the problem of poor stress release caused by the squeezing and closing of the crack surface in stress relief blasting, ensuring the construction efficiency and improving the rock burst risk in the excavation of deep buried tunnels.

[0085] In one embodiment, a stress relief blasting device for deep buried tunnels based on fracture surface reflection is provided. Referring to Figure 9 As shown, the stress relief blasting device 900 for deep buried tunnels based on fracture surface reflection may include: a parameter acquisition module 901, a blast hole arrangement module 902, and a detonation module 903.

[0086] Among them, the parameter acquisition module 901 is used to acquire the rock mass stress state parameters and rock strength of the tunnel face of the deep buried tunnel;

[0087] The blast hole arrangement module 902 is used to arrange multiple rows of outer blast holes on the outermost side of the tunnel face and multiple rows of main blast holes in the middle of the tunnel face according to the rock mass stress state parameters and rock strength;

[0088] The initiation module 903 is used to initiate the outer blast holes first to form a fracture surface during blasting, and then initiate the main blast holes; wherein, the fracture surface is used to reflect the stress wave generated when the main blast holes are detonated.

[0089] In one embodiment, the rock mass stress state parameters include the direction of the maximum principal stress; the outer blast holes and the main blast holes are arranged parallel to the direction of the maximum principal stress.

[0090] In one embodiment, the rock mass stress state parameters further include the magnitude of the maximum principal stress; the blast hole arrangement module 902 is specifically configured to determine the crack propagation length of the tunnel face under the current in-situ stress conditions according to the magnitude of the maximum principal stress and the rock strength; and determine the number of blast holes in each row of the outer blast holes according to the crack propagation length and the width of the tunnel parallel to the direction of the maximum principal stress.

[0091] In one embodiment, the distance between any two adjacent outer blast holes satisfies the distance condition l≤2l; where l is the crack propagation length.

[0092] In one embodiment, after the stress wave generated when the main blast holes are detonated is attenuated by the row spacing, the peak value of the stress wave reflected by the fracture surface is greater than the tensile strength of the rock; the row spacing represents the distance between the outer blast holes and the main blast holes.

[0093] In one embodiment, the blast hole depths of the outer blast holes and the main blast holes are arranged as a set multiple of the expected excavation footage.

[0094] In one embodiment, the outer blast holes are arranged to incline at a set angle range towards the tunnel face.

[0095] In one embodiment, the bottom charging lengths of the outer blast holes and the main blast holes are arranged in a set length range.

[0096] In one embodiment, the outer blast holes and the main blast holes are initiated in a bottom initiation manner.

[0097] For the specific limitations of the deep-buried tunnel stress relief blasting device 900 based on fracture surface reflection, reference can be made to the limitations of the deep-buried tunnel stress relief blasting method based on fracture surface reflection in the above text, which will not be elaborated here. Each module in the above deep-buried tunnel stress relief blasting device 900 based on fracture surface reflection can be implemented in whole or in part by software, hardware and their combinations. The above modules can be embedded in the processor of the computer device in hardware form or be independent of it, or be stored in the memory of the computer device in software form, so that the processor can call and execute the operations corresponding to the above modules.

[0098] Note that the logic and / or steps represented in the flowchart or described otherwise herein, for example, can be considered as a definite sequence list of executable instructions for implementing logical functions, and can be specifically implemented in any computer-readable medium for use by an instruction execution system, apparatus, or device (such as a computer-based system, a system including a processor, or other systems that can fetch and execute instructions from the instruction execution system, apparatus, or device), or used in combination with these instruction execution systems, apparatus, or devices. For the purposes of this specification, a "computer-readable medium" can be any device that can contain, store, communicate, propagate, or transport a program for use by or in connection with an instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of the computer-readable medium include the following: an electrical connection part having one or more wirings (electronic device), a portable computer diskette (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disc read-only memory (CDROM). Additionally, the computer-readable medium can even be paper or other suitable medium on which the program can be printed, because the program can be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, interpretation, or other suitable processing as necessary, and then stored in a computer memory.

[0099] It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, any one or a combination of the following techniques well known in the art can be used: discrete logic circuits having logic gate circuits for implementing logical functions on data signals, application specific integrated circuits having appropriate combinational logic gate circuits, programmable gate arrays (PGAs), field programmable gate arrays (FPGAs), etc.

[0100] In the description of this specification, the description referring to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples", etc. means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0101] 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 quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0102] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A stress relief blasting method for deep-buried tunnels based on fracture surface reflection, characterized in that Comprising: Obtaining the rock mass stress state parameters and rock strength of the heading face of a deep-buried tunnel; According to the rock mass stress state parameters and the rock strength, arranging multiple rows of outer blast holes at the outermost side of the heading face and arranging multiple rows of main blast holes in the middle of the heading face; During blasting, first detonating the outer blast holes to form a fracture surface, and then detonating the main blast holes; wherein, the fracture surface is used to reflect the stress wave generated when the main blast holes are detonated.

2. The stress relief blasting method for deep-buried tunnels based on fracture plane reflection according to claim 1, wherein, The rock mass stress state parameters include the maximum principal stress direction; the outer blast holes and the main blast holes are arranged parallel to the maximum principal stress direction.

3. The stress relief blasting method for deep-buried tunnels based on fracture plane reflection according to claim 1, characterized in that, The rock mass stress state parameters further include the maximum principal stress magnitude; the arranging multiple rows of outer blast holes at the outermost side of the heading face includes: Determining the crack propagation length of the heading face under the current in-situ stress conditions according to the maximum principal stress magnitude and the rock strength; Determining the number of blast holes in each row of outer blast holes according to the crack propagation length and the width of the tunnel parallel to the maximum principal stress direction.

4. The stress relief blasting method for deep-buried tunnels based on fracture surface reflection according to claim 3, characterized in that, The spacing between any two adjacent outer blast holes satisfies the spacing condition L≤2l; where l is the crack propagation length.

5. The stress relief blasting method for deep-buried tunnels based on fracture surface reflection according to claim 1, characterized in that, After the stress wave generated when the main blast holes are detonated is attenuated by the row spacing, the peak value of the stress wave reflected by the fracture surface is greater than the rock tensile strength; the row spacing represents the distance between the outer blast holes and the main blast holes.

6. The stress relief blasting method for deep-buried tunnels based on fracture surface reflection according to claim 1, wherein, The blast hole depths of the outer blast holes and the main blast holes are arranged as a set multiple of the expected excavation footage.

7. The stress relief blasting method for deep-buried tunnels based on fracture surface reflection according to claim 1, wherein The outer blast holes are arranged to incline within a set angle range towards the heading face.

8. The stress relief blasting method for deep-buried tunnels based on fracture plane reflection according to claim 1, wherein The bottom charging lengths of the outer blast holes and the main blast holes are arranged within a set length range.

9. The stress relief blasting method for deep-buried tunnels based on fracture surface reflection according to claim 8, characterized in that, Adopting the bottom initiation method to initiate the outer blast holes and the main blast holes.

10. A stress relief blasting device for deep-buried tunnels based on fracture surface reflection, characterized in that Comprising: A parameter acquisition module for obtaining the rock mass stress state parameters and rock strength of the heading face of a deep-buried tunnel; A blast hole arrangement module for arranging multiple rows of outer blast holes at the outermost side of the heading face and arranging multiple rows of main blast holes in the middle of the heading face according to the rock mass stress state parameters and the rock strength; An initiation module for first detonating the outer blast holes to form a fracture surface and then detonating the main blast holes during blasting; Wherein, the fracture surface is used to reflect the stress wave generated when the main blast holes are detonated.

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