Tunnel drilling and blasting method peripheral hole dynamic design method and system based on back break control

Abstract

The invention discloses a tunnel drilling and blasting method peripheral hole dynamic design method and system based on back break control, belongs to the technical field of engineering blasting, and aims to solve the problem of serious back break caused by insufficient drilling precision of peripheral holes in the tunnel blasting construction process. Dynamic peripheral hole drilling parameters are designed through the following steps that firstly, the distance between a primary support and a tunnel face and the primary support thickness are measured on site, and the excavation footage and the maximum overexcavation amount of the hole bottom are set; 2, selecting a peripheral hole arrangement mode according to the excavation footage; 3, according to the arrangement mode of the peripheral holes, drilling parameters of the peripheral holes are dynamically designed; 4, field blasting construction is guided according to the drilling parameters of the peripheral holes; and (5) the blasting effect is monitored, the hole bottom maximum overexcavation amount, the excavation footage and the peripheral hole arrangement mode are optimized, the explosive loading amount and the explosive loading structure of the peripheral holes are optimized, the step (3) and the step (4) are circulated, and accurate control over overexcavation and under-excavation is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of engineering blasting, and in particular relates to a method and system for dynamic design of peripheral holes of a tunnel drilling and blasting method based on overbreak and underbreak control. Background Art

[0002] At present, tunnel construction mainly adopts the drilling and blasting method for cyclic excavation. During the drilling and blasting on-site construction process, due to the influence of the initial support, it is difficult to drill holes horizontally along the excavation line in the peripheral holes, and holes are drilled outside the excavation contour line at a large angle, resulting in a large amount of over-excavation. Studies have shown that drilling accuracy has the greatest impact on over-excavation and under-excavation, reaching 39.9%. At the same time, with the rapid development of tunnel construction in my country and the continuous improvement of tunnel construction technology, the excavation footage has gradually increased, and the impact of peripheral hole accuracy on tunnel over-excavation and under-excavation has become more prominent.

[0003] The construction process of drilling and blasting is a complex excavation production process with the interaction and influence of man, machine, rock and environment. Therefore, during the tunnel construction process, the distance between the initial support and the heading face, the thickness of the initial support, the excavation footage, the maximum over-excavation at the bottom of the hole and other parameters are constantly changing. The drilling accuracy mainly includes the radial opening position of the peripheral holes, the extrapolation angle, and the drilling length. The radial opening position and extrapolation angle are very sensitive to the above parameters, and there are differences in each cycle.

[0004] At present, the research on peripheral hole parameter optimization mainly focuses on the spacing between holes and the extrapolation angle. However, there are relatively few studies on the dynamic design of peripheral holes and the clarification of parameters such as the opening position and the extrapolation angle in combination with the on-site operation environment and considering the operability of operators. In order to improve the drilling accuracy and control the over-break and under-break, the operation process of tunnel blasting peripheral holes was studied, and a dynamic design construction method for tunnel drilling and blasting peripheral holes based on over-break and under-break control was proposed. Summary of the invention

[0005] The purpose of the present invention is to provide a method and system for dynamic design of peripheral holes in tunnel drilling and blasting method based on over-break and under-break control, which can solve the serious over-break and under-break problem caused by insufficient drilling precision of peripheral holes in tunnel blasting construction process, and quantify the theoretical over-break, under-break, opening position, extrapolation angle and hole depth of each cycle by presetting the maximum over-break at the bottom of the hole and actual parameters such as the distance of initial support from the face, initial support thickness and excavation footage determined by on-site measurement. On this basis, the drilling parameters are dynamically designed in combination with the actual over-break and under-break situation after blasting and the efficacy, cost and operability of over-break and under-break treatment to achieve the best economic and social benefits.

[0006] In a first aspect, the present invention provides a method for dynamic design of peripheral holes of a tunnel drilling and blasting method based on overbreak and underbreak control, the method comprising the following steps:

[0007] Step 1: Measure the distance between the initial support and the tunnel face and the thickness of the initial support on site, and set the excavation footage and the maximum over-excavation at the bottom of the hole;

[0008] Step 2: Select the peripheral hole arrangement method according to the excavation footage;

[0009] Step 3: Dynamically design the drilling parameters of the peripheral holes according to the arrangement of the peripheral holes;

[0010] Step 4: Guide the on-site blasting construction according to the drilling parameters of the surrounding holes;

[0011] Step 5: Monitor the blasting effect, optimize the maximum over-excavation at the bottom of the hole, the excavation footage and the layout of the peripheral holes, and optimize the charge amount and charge structure of the peripheral holes. Repeat steps 2 to 4 to achieve precise control of over-excavation and under-excavation.

[0012] Furthermore, in step 2, the arrangement of the peripheral holes includes double-row peripheral holes and single-row peripheral holes. When the excavation footage is ≤2m, the single-row peripheral holes are used; when the excavation footage is >2m, the double-row peripheral holes are used.

[0013] Furthermore, when a single row of peripheral holes is used, the drilling parameters include the opening position of the peripheral holes, the external insertion angle of the peripheral holes, the hole depth of the peripheral holes, the theoretical overbreak area and the theoretical underbreak area, which are calculated as follows:

[0014]

[0015] X=DA×tan(α)

[0016]

[0017] In the above formula, A represents the distance between the initial support and the tunnel face, B represents the excavation footage, C represents the maximum over-excavation at the bottom of the hole, D represents the initial support thickness, α represents the external insertion angle of the peripheral holes, X represents the distance between the opening position of the peripheral holes and the designed excavation contour line, L represents the depth of the peripheral holes, S represents the maximum over-excavation at the bottom of the hole, and c is the theoretical over-excavation area, which is calculated by multiplying the theoretical over-excavation area by the perimeter of the tunnel excavation contour line; S q The theoretical under-break area is the product of the theoretical under-break area and the perimeter of the tunnel excavation contour line, which is the theoretical under-break volume.

[0018] Furthermore, when there are double rows of peripheral holes, the drilling parameters include the drilling position of the long peripheral holes, the external insertion angle of the long peripheral holes, the hole depth of the long peripheral holes, the drilling position of the short peripheral holes, the external insertion angle of the short peripheral holes, the hole depth of the short peripheral holes, the theoretical over-excavation area and the theoretical under-excavation area.

[0019] Furthermore, when there are two rows of peripheral holes, the drilling parameters are calculated as follows:

[0020]

[0021] X c =DA×tan(α′)

[0022]

[0023] X d =DA×tan(β)

[0024]

[0025]

[0026] In the above formula, α′ represents the external insertion angle of the long peripheral hole, X c Indicates the distance between the opening position of the long peripheral hole and the designed excavation contour line, L c represents the hole depth of the long peripheral hole, β represents the external insertion angle of the short peripheral hole, and X d Indicates the distance between the opening position of the short peripheral hole and the designed excavation contour line, L d Indicates the hole depth of the short perimeter hole, S c The theoretical over-excavation area is multiplied by the tunnel excavation contour perimeter to get the theoretical over-excavation volume. q The theoretical under-break area is the product of the theoretical under-break area and the perimeter of the tunnel excavation contour line, which is the theoretical under-break volume.

[0027] Furthermore, in step 5, the optimization method of the charging structure is as follows: during the construction process, the charging structure is determined in combination with the roundness of the excavation contour line and the residual rate of the blasthole. When the residual rate of the blasthole is high and the excavation contour line is round, a continuous charging structure is adopted. Otherwise, concentrated energy blasting is adopted for an intermittent charging structure.

[0028] In a second aspect, the present invention further provides a drilling parameter design system for peripheral holes of a tunnel drilling and blasting method based on overbreak and underbreak control, the system is implemented by using the above-mentioned method for designing drilling parameters of peripheral holes of a tunnel drilling and blasting method based on overbreak and underbreak control, and comprises:

[0029] The acquisition module measures the distance between the initial support and the tunnel face and the initial support thickness on site, and sets the excavation footage and the maximum over-excavation at the bottom of the hole;

[0030] Select the module and choose the layout of the peripheral holes according to the excavation footage;

[0031] The calculation module dynamically designs the drilling parameters of the peripheral holes according to the arrangement of the peripheral holes;

[0032] Output module, outputs the calculated drilling parameters.

[0033] Compared with the prior art, the present invention has the following advantages:

[0034] 1. The present invention proposes a method for dynamic design of peripheral holes in tunnel drilling and blasting based on over-break and under-break control. In order to realize the feasibility of dynamic design of peripheral holes and facilitate on-site actual operation of operators, a "Peripheral Hole Optimization Assistant" mobile phone APP program, that is, a drilling parameter design system for peripheral holes, is developed. Operators measure the distance of the initial support from the heading face and the thickness of the initial support on-site, set actual parameters such as over-break and under-break, excavation footage, and input them into the mobile phone APP to quickly calculate the blasthole parameters, providing practical parameters for drilling construction. It is easy to operate, simple and easy to learn, and has strong practical operability.

[0035] 2. The present invention presets the maximum overbreak at the bottom of the hole, and quantifies the theoretical overbreak, theoretical underbreak, opening position of peripheral holes, external insertion angle of peripheral holes, and hole depth of peripheral holes according to actual parameters such as the distance from the initial support to the face, the thickness of the initial support, and the excavation footage determined by on-site measurement, thereby realizing the rapid dynamic design of each cycle. On this basis, combined with the actual overbreak and underbreak after blasting, the efficacy, cost, operability of operators, and the impact of charging parameters on the blasting effect, the calculation parameters of each cycle are dynamically optimized and adjusted to achieve the effects of accurately controlling overbreak and underbreak, reducing engineering costs, and reducing environmental pollution, with significant economic and social benefits.

[0036] 3. In order to effectively reduce the maximum overbreak at the bottom of a large-footprint excavation hole and balance the amount of overbreak and underbreak, the present invention reduces the maximum overbreak at the bottom of the long peripheral hole by adding a row of short peripheral holes to reduce the external insertion angle of the long peripheral hole, thereby reducing the short peripheral holes. At the same time, the short peripheral holes are used to reduce the underbreak at the opening caused by the reduction of the external insertion angle of the long peripheral holes, thereby achieving the purpose of reducing the linear average overbreak. The opening position of the long peripheral hole is offset to the inside of the designed excavation contour line, so that the drilling construction is not restricted by the previous cycle steel arch frame and has operability; although the hole mouth of the short peripheral hole is closer to the designed excavation contour line, its external insertion angle is larger and the blasthole depth is smaller. Although the construction space is limited, it is operable. The double-row peripheral holes replace the single-row peripheral holes in the traditional blasting design, which is conducive to the blasting formation of the peripheral holes and can effectively control the overbreak and underbreak of the tunnel. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is the construction process flow chart;

[0038] Figure 2 It is a single row peripheral hole layout diagram;

[0039] Figure 3 This is the cross-sectional arrangement diagram of the "long and short" double-row peripheral holes;

[0040] Figure 4 This is the interface diagram of the software for calculating single-row peripheral holes;

[0041] Figure 5"Long and short" double row peripheral hole calculation software interface diagram;

[0042] Figure 6 Take on-site photos to mark hole positions;

[0043] Figure 7 This is a photo of the explosion scene.

[0044] Among them, 1-initial support; 2-palm face. DETAILED DESCRIPTION

[0045] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more definite definition of the protection scope of the present invention.

[0046] Example 1

[0047] This embodiment specifically provides a method for dynamic design of peripheral holes of a tunnel drilling and blasting method based on overbreak and underbreak control, and the design method comprises the following steps:

[0048] Step 1: Measure the distance between initial support 1 and tunnel face 2 and the thickness of initial support 1 on site, and set the excavation footage and maximum over-excavation at the bottom of the hole;

[0049] Step 2: Select the peripheral hole arrangement method according to the excavation footage;

[0050] Step 3: Dynamically design the drilling parameters of the peripheral holes according to the arrangement of the peripheral holes;

[0051] Step 4: Guide the on-site blasting construction according to the drilling parameters of the surrounding holes;

[0052] Step 5: Monitor the blasting effect, optimize the maximum over-excavation at the bottom of the hole, the excavation footage and the layout of the peripheral holes, and optimize the charge amount and charge structure of the peripheral holes. Repeat steps 3 and 4 to achieve precise control of over-excavation and under-excavation.

[0053] In step 1, the distance between the initial support 1 and the tunnel face 2 and the thickness of the initial support 1 should be determined on-site for each cycle; the excavation footage should be comprehensively evaluated in combination with monitoring measurement, advanced geological forecast, specifications and owner requirements; the maximum over-excavation at the bottom of the hole is the set over-excavation control target, which should be reasonably set in combination with the hardness of the surrounding rock, the development of joints and the construction efficiency.

[0054] The drilling parameters are very sensitive to the above four input parameters, and the actual input parameters of each cycle are different, so the input parameters of each cycle should be actually measured and set.

[0055] The peripheral hole arrangement methods in step 2 include "long and short" double-row peripheral holes and single-row peripheral holes. When the excavation depth is ≤2m, single-row peripheral holes are used; when the excavation depth is >2m, "long and short" double-row peripheral holes are used.

[0056] When a single row of peripheral holes is used, the drilling parameters include the opening position of the peripheral holes, the external insertion angle of the peripheral holes, the hole depth of the peripheral holes, the theoretical over-break area and the theoretical under-break area, which are calculated as follows:

[0057]

[0058] X=DA×tan(α)

[0059]

[0060] In the above formula, A represents the distance between the initial support and the tunnel face, B represents the excavation footage, C represents the maximum over-excavation at the bottom of the hole, D represents the initial support thickness, α represents the external insertion angle of the peripheral holes, X represents the distance between the opening position of the peripheral holes and the designed excavation contour line, L represents the depth of the peripheral holes, S represents the maximum over-excavation at the bottom of the hole, and c is the theoretical over-excavation area, which is calculated by multiplying the theoretical over-excavation area by the perimeter of the tunnel excavation contour line; S q The theoretical under-break area is the product of the theoretical under-break area and the perimeter of the tunnel excavation contour line, which is the theoretical under-break volume.

[0061] When there are two rows of “long and short” peripheral holes, the drilling parameters include the drilling position of the long peripheral holes, the external insertion angle of the long peripheral holes, the hole depth of the long peripheral holes, the drilling position of the short peripheral holes, the external insertion angle of the short peripheral holes, the hole depth of the short peripheral holes, the theoretical over-break area and the theoretical under-break area.

[0062] The calculation is as follows:

[0063]

[0064] X c =DA×tan(α′)

[0065]

[0066] X d =DA×tan(β)

[0067]

[0068] In the above formula, α′ represents the external insertion angle of the long peripheral hole, X c Indicates the distance between the opening position of the long peripheral hole and the designed excavation contour line, L c represents the hole depth of the long peripheral hole, β represents the external insertion angle of the short peripheral hole, and X dIndicates the distance between the opening position of the short peripheral hole and the designed excavation contour line, L d Indicates the hole depth of the short perimeter hole, S c The theoretical over-excavation area is multiplied by the tunnel excavation contour perimeter to get the theoretical over-excavation volume. q The theoretical under-break area is the product of the theoretical under-break area and the perimeter of the tunnel excavation contour line, which is the theoretical under-break volume.

[0069] Example 2

[0070] This embodiment is based on the two peripheral hole parameter calculation methods in Example 1. The "Peripheral Hole Optimization Assistant" mobile phone APP program developed in this embodiment sets dual modes of "single row peripheral holes" and "double row peripheral holes". The actual parameters can be input to quickly calculate the blast hole parameters and guide on-site construction.

[0071] Specifically, a drilling parameter design system for peripheral holes of a tunnel drilling and blasting method based on overbreak and underbreak control, the system comprises:

[0072] The acquisition module inputs the distance between the initial support 1 and the tunnel face 2, the excavation footage, the maximum over-excavation at the bottom of the hole, and the thickness of the initial support 1 measured on site;

[0073] Select the module and choose the layout of the peripheral holes according to the excavation footage;

[0074] The calculation module calls the single-row peripheral hole drilling parameter calculation method or the "long and short" double-row peripheral hole drilling parameter calculation method to calculate the peripheral hole drilling parameters (such as Figure 4 and Figure 5 shown);

[0075] Output module, outputs the calculated drilling parameters.

[0076] In this embodiment, the peripheral hole arrangement includes "long and short" double-row peripheral holes and single-row peripheral holes. When the excavation depth is ≤2m, a single-row peripheral holes is used; when the excavation depth is >2m, a "long and short" double-row peripheral holes is used.

[0077] Calculation method for drilling parameters of single row peripheral holes:

[0078]

[0079] X=DA×tan(α)

[0080]

[0081] In the above formula, A represents the distance between the initial support and the tunnel face, B represents the excavation footage, C represents the maximum over-excavation at the bottom of the hole, D represents the initial support thickness, α represents the external insertion angle of the peripheral holes, X represents the distance between the opening position of the peripheral holes and the designed excavation contour line, L represents the depth of the peripheral holes, S represents the maximum over-excavation at the bottom of the hole, andc is the theoretical over-excavation area, which is calculated by multiplying the theoretical over-excavation area by the perimeter of the tunnel excavation contour line; S q The theoretical under-break area is the product of the theoretical under-break area and the perimeter of the tunnel excavation contour line, which is the theoretical under-break volume.

[0082] Calculation method for drilling parameters of "long and short" double-row peripheral holes:

[0083]

[0084] X c =DA×tan(α′)

[0085]

[0086] X d =DA×tan(β)

[0087]

[0088] In the above formula, α′ represents the external insertion angle of the long peripheral hole, X c Indicates the distance between the opening position of the long peripheral hole and the designed excavation contour line, L c represents the hole depth of the long peripheral hole, β represents the external insertion angle of the short peripheral hole, and X d Indicates the distance between the opening position of the short peripheral hole and the designed excavation contour line, L d Indicates the hole depth of the short perimeter hole, S c The theoretical over-excavation area is multiplied by the tunnel excavation contour perimeter to get the theoretical over-excavation volume. q The theoretical under-break area is the product of the theoretical under-break area and the perimeter of the tunnel excavation contour line, which is the theoretical under-break volume.

[0089] Example 3

[0090] This embodiment provides a construction method for dynamic design of peripheral holes of tunnel drilling and blasting method based on overbreak and underbreak control, such as Figure 1-7 As shown, the construction method comprises the following steps:

[0091] Step 1: Measure and lay out

[0092] Measurement and layout are the prerequisites for ensuring the precise location of the blastholes. It is advisable to use high-precision measuring instruments to accurately measure and set excavation contour points every 50 to 100 cm along the excavation contour line. The accuracy of the measuring points should be controlled within ±10mm. Then all the measuring points are connected in sequence to form the excavation contour line, which provides a benchmark for the subsequent measurement of blasthole parameters and blasthole position layout.

[0093] Step 2: Parameter measurement and setting

[0094] In each cycle, on-site measurements should be taken to determine the distance between initial support 1 and face 2 and the thickness of initial support 1. The excavation progress should be comprehensively evaluated in combination with monitoring measurements, advanced geological forecasts, specifications and owner requirements. A reasonable maximum over-excavation amount at the bottom of the hole should be set in combination with the hardness of the surrounding rock, the development of joints and construction efficiency.

[0095] Step 3: Dynamic design of drilling parameters for peripheral holes

[0096] By presetting the maximum over-excavation at the bottom of the hole, the theoretical over-excavation and under-excavation are calculated according to the distance between initial support 1 and face 2, the thickness of initial support 1, and the actual excavation footage parameters. The drilling parameters are dynamically designed based on the efficacy, cost, and operability of over-excavation and under-excavation treatment.

[0097] Specific method: On-site workers will input the actual parameters of the initial support distance from the heading face, initial support thickness, and excavation footage measured on site into the "Peripheral Hole Optimization Assistant" APP to calculate the actual parameters such as the peripheral hole opening position, angle, and hole depth.

[0098] Step 4: Hole Lofting

[0099] Measure the distance of the excavation outline with a ruler, and then use red paint to mark the opening positions of the peripheral holes. When the excavation surface is relatively uneven, the opening positions of the peripheral holes must be calculated one by one.

[0100] Step 5: Start drilling according to the hole location results

[0101] According to the results of the survey and layout, use a pneumatic rock drill or a hyperbolic rock drill trolley to drill holes. During the drilling operation, the drill bit is aligned with the opening position mark, and the drill rod is in close contact with the outer surface of the end of the initial support 1 of the previous cycle, which can ensure the accuracy of the external insertion angle and the opening position. At the same time, during the drilling process, the hole depth should be strictly controlled to further improve the drilling accuracy; after the blasthole is completed, the depth and slope of each hole should be checked, and the long blasting stick should be inserted into the hole for inspection and records should be kept; after the drilling is completed, the blasting hook made of steel bars and a small-diameter high-pressure air duct are used to input high-pressure air to blow out the rock chips, gravel, and mud in the hole; for the blastholes that fail the inspection, the blastholes are collapsed, and the blastholes that cannot be cleaned and used, re-drill holes near them.

[0102] The drilling accuracy requirements are as follows: when the blasthole depth is less than 2m, the allowable error of the distance between the surrounding holes is ±5cm, and the error of the distance between the surrounding holes and the excavation contour line is ±2cm; when the blasthole depth is greater than 2m, the allowable error of the distance between the surrounding holes is ±5cm, and the error of the distance between the surrounding holes and the excavation contour line is ±1cm.

[0103] Step 6: Charge

[0104] After the hole is cleaned, charging is carried out. Continuous charging structure is adopted for grooved holes, bottom plate holes, peripheral holes and auxiliary holes. Reverse charging is adopted for non-gas operation section and forward charging is adopted for gas operation section. The charging amount must be carried out according to the blasting design. When charging, the charges are loaded to the bottom of the hole and the explosive package is slowly fed in with a gun stick to prevent pulling the detonator or damaging the detonating cord. Before charging, the preset number of sections should be marked on the detonator decoder. The loading of explosives must be carried out according to safety regulations and must not be forced or rammed. After charging, the inspectors shall review the number of detonator sections to ensure accuracy and check the specifications of the medicine rolls and the charging length to ensure that the charging of each hole meets the design requirements. Records shall be kept after inspection.

[0105] The blastholes for charging should be plugged with gun mud, which should be made by gun mud machine. The packaging materials of explosives should not be used instead of gun mud. Gun mud should be made by mixing clay and sand. Gun mud should be made by mixing sand: clay: water = 3:1:1. The length of the plugging of the peripheral holes for smooth blasting should not be less than 30cm; for other blastholes with a depth of less than 1m, the length of the plugging should not be less than 1 / 2 of the depth of the blasthole, the length of the plugging should not be less than 0.5m for depths of 1m to 2.5m, and the length of the plugging should not be less than 1m for depths exceeding 2.5m.

[0106] Step 7: Detonation

[0107] The blasting network is connected by the blaster according to the network connection method determined by the blasting plan, and is reviewed by a dedicated person. Blasting can only be carried out after the safety supervisor has reviewed and confirmed. Before detonation, a safety alert is set at the tunnel entrance to be blasted, and the alert range set in the direction of the tunnel entrance is required to be no less than 300m. All irrelevant personnel evacuate the danger zone, and notify the personnel in the tunnel to be alert, so that all passages are under surveillance to prevent personnel and machinery from entering the danger zone by mistake. Before blasting, the number of people must be counted, and the detonation order can only be issued after confirmation. After receiving the detonation order, the detonator must issue a blasting alarm and wait for 5 seconds before detonation.

[0108] After the blasting, the blaster should check whether there are any unexploded detonators on the blaster. After 15 minutes of ventilation and smoke exhaust, the blaster who detonated the blast or the safety officer shall enter the working face to check for dangerous rocks, blind shots, residual explosives, unexploded detonators, etc. When blind shots, residual explosives and detonators are found, they must be handled according to regulations by the original blasting personnel. After the danger has been eliminated and confirmed by the safety officer, other personnel may enter the blasting hole.

[0109] Step 8: Slag removal

[0110] Excavators and manual labor are used to remove dangerous rocks. After the removal is completed, other personnel are allowed to enter only after the safety officer has checked and approved them. The slag is transported by dump trucks, and the waste slag must not be transported fully loaded or overloaded. The transportation process should be covered with closed cloth to prevent dust from falling.

[0111] Step 9: Blasting effect check

[0112] After the blasting is completed and before finding the top, the contour rock surface is realistically described, and the surrounding rock strength is measured when necessary. The visual estimation method can be used to check the preservation rate of blasthole marks and evaluate the blasting effect. A three-dimensional cross-section scanner is used to check the excavation contour line, analyze the over-excavation and under-excavation area and volume, and record them in detail. During the top finding process, the under-excavation supplementary processing time is recorded to provide a basis for the subsequent optimization of construction parameters.

[0113] The inspection contents of the blasting effect inspection mainly include the preservation rate of blasthole traces around the tunnel blasting and the over-excavation and under-excavation. Hard rock should not be less than 80%, medium-hard rock should not be less than 60%, and should be evenly distributed on the contour surface. The tunnel should strictly control under-excavation, and the under-excavation of individual protruding parts of the rock (no more than 0.1㎡ per 1㎡) should not be greater than 5cm. The allowable over-excavation value of tunnel excavation should meet the requirements of the following table.

[0114] Table 1 Allowable over-excavation value of tunnel

[0115]

[0116] Step 10: Optimize peripheral hole parameters based on blasting results

[0117] It is mainly carried out from two aspects: drilling parameter optimization and charging parameter optimization; drilling parameter optimization includes optimization adjustment of maximum over-excavation at the bottom of the hole, optimization of excavation footage and optimization of peripheral hole layout; charging parameter optimization includes optimization of charging amount adjustment and optimization of charging structure.

[0118] Optimization and adjustment of the maximum overbreak at the bottom: The maximum overbreak at the bottom of the hole is the main factor that determines the linear average overbreak, and is also the set overbreak control target; therefore, during the construction process, the actual work efficiency of mechanical removal of the underbreak part and the cost of the overbreak backfill part should be counted, and a comprehensive analysis should be conducted in combination with the hardness of the surrounding rock and the degree of development of joints and fissures to determine the optimal target value. When the surrounding rock has good integrity and high hardness, and underbreak is difficult to handle, the overbreak target value should be adjusted accordingly; when the surrounding rock has average integrity and average hardness, and underbreak is easier to handle, the overbreak target value should be adjusted accordingly.

[0119] Optimization of excavation advance: In the actual construction process, the larger the excavation advance, the more difficult it is to control over-excavation and under-excavation. Therefore, first, it should be combined with monitoring measurement, advanced geological prediction, specifications and owner requirements; second, it should not blindly pursue progress or over-excavation and under-excavation control; third, it should be combined with actual parameters such as the distance between initial support 1 and face 2, the thickness of initial support 1, and excavation advance to find a balance point and reasonably formulate the optimal excavation advance; when the distance to face 2 is too close, the excavation advance adjustment can be appropriately reduced.

[0120] Optimization of peripheral hole arrangement: By pre-setting the maximum over-excavation at the bottom of the hole, the theoretical over-excavation and under-excavation are calculated according to actual parameters such as the distance between initial support 1 and face 2, the thickness of initial support 1, and the excavation footage. The drilling parameters are dynamically designed based on the over-excavation and under-excavation treatment efficiency, cost, and operability of the operators, and single-row peripheral holes or "long and short" double-row peripheral holes are reasonably selected.

[0121] Adjustment and optimization of charge amount: The charge amount of peripheral blastholes is an important factor affecting over-break and under-break. Therefore, during the construction process, the over-break amount and blasthole residual rate should be combined to optimize the charge amount of peripheral holes. When the blasthole residual rate is high and the over-break and under-break amount do not deviate much from the design, it means that the charge amount is appropriate; otherwise, the charge amount should be reduced or increased depending on the actual situation.

[0122] Optimization of charging structure: The charging method of peripheral blastholes has an important influence on over-excavation and under-excavation. Therefore, during the construction process, the appropriate charging structure should be determined in combination with the roundness of the excavation contour and the residual rate of the blastholes. When the residual rate of the blastholes is high and the excavation contour is round, a continuous charging structure can be used; otherwise, concentrated energy blasting should be used for intermittent charging.

[0123] The above are only a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the present application. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method for dynamic design of peripheral holes in tunnel drilling and blasting method based on overbreak and underbreak control, characterized in that: The design method includes the following steps: Step 1: Measure the distance between the initial support and the tunnel face and the initial support thickness on site, and set the excavation footage and the maximum over-excavation at the bottom of the hole; Step 2: Select the peripheral hole arrangement method according to the excavation footage; Step 3: Dynamically design the drilling parameters of the peripheral holes according to the arrangement of the peripheral holes; Step 4: Guide the on-site blasting construction according to the drilling parameters of the surrounding holes; Step 5: Monitor the blasting effect, optimize the maximum over-excavation at the bottom of the hole, the excavation footage and the layout of the peripheral holes, and optimize the charge amount and charge structure of the peripheral holes. Repeat steps 1 to 4 to achieve precise control of over-excavation and under-excavation.

2. The method for dynamic design of peripheral holes of tunnel drilling and blasting method based on overbreak and underbreak control according to claim 1 is characterized in that: The peripheral hole arrangement in step 2 includes double-row peripheral holes and single-row peripheral holes. When the excavation depth is ≤2m, single-row peripheral holes are used; when the excavation depth is >2m, double-row peripheral holes are used.

3. The method for dynamic design of peripheral holes of tunnel drilling and blasting method based on overbreak and underbreak control according to claim 2 is characterized in that: When a single row of peripheral holes is used, the drilling parameters include the opening position of the peripheral holes, the external insertion angle of the peripheral holes, the hole depth of the peripheral holes, the theoretical over-break area and the theoretical under-break area, which are calculated as follows: X=DA×tan(α) In the above formula, A represents the distance between the initial support and the tunnel face, B represents the excavation footage, C represents the maximum over-excavation at the bottom of the hole, D represents the initial support thickness, α represents the external insertion angle of the peripheral holes, X represents the distance between the opening position of the peripheral holes and the designed excavation contour line, L represents the depth of the peripheral holes, S represents the maximum over-excavation at the bottom of the hole, and c is the theoretical over-excavation area, which is calculated by multiplying the theoretical over-excavation area by the perimeter of the tunnel excavation contour line; S q The theoretical under-break area is the product of the theoretical under-break area and the perimeter of the tunnel excavation contour line, which is the theoretical under-break volume.

4. The method for dynamic design of peripheral holes of tunnel drilling and blasting method based on overbreak and underbreak control according to claim 3 is characterized in that: When there are double rows of peripheral holes, the drilling parameters include the drilling position of the long peripheral holes, the external insertion angle of the long peripheral holes, the hole depth of the long peripheral holes, the drilling position of the short peripheral holes, the external insertion angle of the short peripheral holes, the hole depth of the short peripheral holes, the theoretical over-break area and the theoretical under-break area.

5. The method for dynamic design of peripheral holes of tunnel drilling and blasting method based on overbreak and underbreak control according to claim 4 is characterized in that: When there are two rows of peripheral holes, the drilling parameters are calculated as follows: X c =DA×tan(α′) X d =DA×tan(β) In the above formula, α′ represents the external insertion angle of the long peripheral hole, X c Indicates the distance between the opening position of the long peripheral hole and the designed excavation contour line, L c represents the hole depth of the long peripheral hole, β represents the external insertion angle of the short peripheral hole, and X d Indicates the distance between the opening position of the short peripheral hole and the designed excavation contour line, L d Indicates the hole depth of the short perimeter hole, S c The theoretical over-excavation area is multiplied by the tunnel excavation contour perimeter to get the theoretical over-excavation volume. q The theoretical under-break area is the product of the theoretical under-break area and the perimeter of the tunnel excavation contour line, which is the theoretical under-break volume.

6. The method for dynamic design of peripheral holes of tunnel drilling and blasting method based on overbreak and underbreak control according to claim 1 is characterized in that: In step 5, the optimization method of the charging structure is as follows: during the construction process, the charging structure is determined in combination with the roundness of the excavation contour line and the residual rate of the blasthole. When the residual rate of the blasthole is high and the excavation contour line is round, a continuous charging structure is adopted. Otherwise, concentrated energy blasting is adopted for an intermittent charging structure.

7. A drilling parameter design system for peripheral holes of tunnel drilling and blasting method based on overbreak and underbreak control, characterized in that: The method according to any one of claims 1 to 5 is implemented, the system comprising: The acquisition module measures the distance between the initial support and the tunnel face and the initial support thickness on site, and sets the excavation footage and the maximum over-excavation at the bottom of the hole; Select the module and choose the layout of the peripheral holes according to the excavation footage; The calculation module dynamically designs the drilling parameters of the peripheral holes according to the arrangement of the peripheral holes; Output module, outputs the calculated drilling parameters.

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