Drilling and blasting construction method for large-section tunnel in urban space

Abstract

The invention discloses a drilling and blasting construction method for a large-section tunnel in an urban space, and relates to the technical field of tunnel construction.The drilling and blasting construction method for the large-section tunnel in the urban space comprises the steps that geological exploration is conducted on a tunnel face of the tunnel, and the geological condition is obtained; the cut area is located in the middle of the tunnel face, the auxiliary area is located on the periphery of the cut area, and the peripheral area is located on the periphery of the auxiliary area and located on the edge of the tunnel face; establishing a blasting model based on geological conditions; determining an arrangement scheme of a blast hole group and a selection scheme of explosives according to the blasting model; a plurality of blast holes are drilled in the slotting area, the auxiliary area and the peripheral area through an automatic rock drilling vehicle according to the arrangement scheme of the blast hole sets; and millisecond blasting is conducted on the multiple blasting holes in the underholing area, the auxiliary area and the peripheral area in sequence. The blast holes are accurately formed, so that the blast range and effect are accurately controlled, disturbance to the surrounding environment is reduced, and tunnel construction safety is guaranteed in the urban space.

Description

Technical Field

[0001] The invention relates to the technical field of tunnel construction, and in particular to a drilling and blasting construction method for a large-section tunnel in an urban space. Background Art

[0002] In the field of tunnel construction, drilling and blasting is a traditional excavation method that is widely used in various tunnel projects. When designing blasting holes, the traditional drilling and blasting method usually divides the blasting range required by the tunnel face equally into each blasting hole, thereby determining the blasting range of each blasting hole, and the layout of each blasting hole is the same.

[0003] However, for large-section tunnels, due to the large area of ​​the face, which usually involves a variety of geological conditions, the blasting effects of the same blasting hole arrangement scheme in different geological conditions are quite different. The same arrangement scheme for multiple blasting holes will lead to inaccurate control of the blasting range and effect, and it is easy to have an uneven blasting surface, affecting the construction quality and aesthetics of the tunnel. Secondly, in terms of the release and transmission of blasting energy, the existing drilling and blasting method often blasts the entire face at once, so that the energy generated by the blasting is released in a concentrated manner, which has a greater disturbance to the surrounding rock, easily destroys the stability of the surrounding rock, increases the safety risk of construction, and easily has a greater impact on the surrounding environment. It is not suitable for use in densely populated urban spaces. Summary of the invention

[0004] The main purpose of the present invention is to propose a drilling and blasting construction method for large-section tunnels in urban spaces, aiming to solve the technical problems in the prior art of large-section tunnel drilling and blasting construction that the blasting range and blasting effect are not accurately controlled and the blasting causes great disturbance to the surrounding environment.

[0005] To achieve the above-mentioned purpose, the drilling and blasting construction method of a large-section tunnel in an urban space proposed in the present invention comprises: conducting geological exploration on the tunnel face to obtain geological conditions; dividing the tunnel face into a groove area located in the middle of the tunnel face, an auxiliary area located outside the groove area, and a peripheral area located outside the auxiliary area and located at the edge of the tunnel face; establishing a blasting model based on the geological conditions; determining the arrangement scheme of a blasting hole group and the selection scheme of explosives according to the blasting model; wherein the blasting hole group comprises a plurality of blasting holes respectively arranged in the groove area, the auxiliary area and the peripheral area; using an automatic rock drilling vehicle to drill a plurality of blasting holes in the groove area, the auxiliary area and the peripheral area according to the arrangement scheme of the blasting hole group; and sequentially performing micro-difference blasting on the plurality of blasting holes in the groove area, the auxiliary area and the peripheral area.

[0006] In one embodiment, the steps of determining the layout plan of the blast hole groups and the selection plan of the explosives according to the blast model include: determining the type of the explosives according to the blast model; determining the maximum charge amount of each blast hole according to the type of the explosives; determining the hole diameter of the blast hole according to the maximum charge amount; calculating the first spacing, the second spacing and the third spacing of the blast hole respectively according to the hole diameter; wherein, the first spacing is the spacing between two adjacent blast holes in the cut area, the second spacing is the spacing between two adjacent blast holes in the auxiliary area, and the third spacing is the spacing between two adjacent blast holes in the perimeter area; determining the depths of the blast holes in the cut area, the auxiliary area and the perimeter area respectively according to the first spacing, the second spacing and the third spacing.

[0007] In one embodiment, the step of determining the type of the explosives according to the blast model includes: determining the type of the explosives in the blast holes located in the cut area and the auxiliary area according to the blast model; the explosives in the blast holes located in the cut area and the auxiliary area are selected as bulk emulsion explosives, non-electric detonators and initiators, and are sealed with plugs; determining the type of the explosives in the blast holes located in the perimeter area according to the blast model; the explosives in the blast holes located in the perimeter area are selected as stick emulsion explosives, non-electric detonators and detonation cords, and are sealed with the plugs.

[0008] In one embodiment, the filling length of the bulk emulsion explosive is 2 m; the weight of the initiator is 20 g or 25 g; the specification of the detonation cord is 40 g / m; the specification of the stick emulsion explosive is φ32 mm, and the length of the stick emulsion explosive is 200 mm; the length of the plug is 0.8 m to 1 m.

[0009] In one embodiment, the hole diameter of the blast holes located in the cut area is 89 mm to 102 mm, and the hole diameter of the blast holes located in the auxiliary area and the perimeter area is ≥50 mm.

[0010] In one embodiment, the first spacing is ≥1 m; the second spacing is ≥1 m; the third spacing is ≥0.6 m.

[0011] In one embodiment, the step of sequentially performing millisecond blasting on multiple blast holes in the cut area, the auxiliary area and the perimeter area includes: performing millisecond blasting on multiple blast holes in the cut area from the middle to the edge of the heading face in sequence; performing millisecond blasting on multiple blast holes in the auxiliary area from the middle to the edge of the heading face in sequence; performing millisecond blasting on multiple blast holes in the perimeter area from the middle to the edge of the heading face in sequence.

[0012] In one embodiment, the step of performing millisecond blasting on the multiple blasting holes in the cut area in sequence from the middle to the edge of the heading face includes: loading an electric detonator into the blasting hole at the very middle of the cut area; loading non-electric detonators into the remaining several blasting holes; connecting the electric detonator and each adjacent non-electric detonator with detonating fuses, and connecting each non-electric detonator with its adjacent non-electric detonator from the middle to the edge of the cut area; detonating the electric detonator so that the several non-electric detonators are detonated in sequence from the middle to the edge of the cut area.

[0013] In one embodiment, after the step of performing millisecond blasting on the multiple blasting holes in the cut area, the auxiliary area, and the perimeter area in sequence, the method further includes: using a vibration measuring instrument to measure the peak particle vibration velocity and the overpressure of the air shock wave in the tunnel during the blasting process to respectively obtain the peak particle vibration velocity value and the overpressure value of the air shock wave; dynamically adjusting the blasting model based on the peak particle vibration velocity value and the overpressure value of the air shock wave.

[0014] In one embodiment, the step of dynamically adjusting the blasting model based on the peak particle vibration velocity value and the overpressure value of the air shock wave includes: establishing the blasting model based on the geological conditions; performing simulated blasting according to the blasting model to obtain the predicted value of the peak particle vibration velocity and the predicted value of the overpressure of the air shock wave; comparing the peak particle vibration velocity value with the predicted value of the peak particle vibration velocity to obtain the peak particle vibration velocity deviation value, and comparing the overpressure value of the air shock wave with the predicted value of the overpressure of the air shock wave to obtain the overpressure deviation value of the air shock wave; correcting the blasting model according to the overpressure deviation value of the air shock wave and the peak particle vibration velocity deviation value.

[0015] The drill and blast construction method for large-section tunnels in urban space proposed by the present invention divides the heading face with a relatively large tunnel area into a cut area, an auxiliary area, and a perimeter area, establishes a blasting model based on the specific geological conditions of the heading face, and performs simulated blasting on the blasting process according to the blasting model, so as to accurately set the layout scheme of each blasting hole in different zones, thereby more precisely controlling the blasting range and blasting effect, making the blasting surface smoother, and effectively improving the blasting construction accuracy. By performing millisecond blasting on the blasting holes in the cut area, the auxiliary area, and the perimeter area in sequence, the energy generated by the blasting of each blasting hole is evenly released and transmitted orderly from the inside to the outside of the heading face, and it is possible to perform the blasting construction of large-section tunnels with a heading face area exceeding 300 square meters, avoiding excessive disturbance to the surrounding rock due to a one-time full-area blasting of the heading face, and effectively reducing the disturbance to the surrounding environment, so as to ensure the stability of the surrounding rock and the construction safety around the tunnel in urban space. Brief Description of the Drawings

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on the structures shown in these drawings.

[0017] Figure 1 It is a schematic structural diagram of an embodiment of the drill and blast construction method for a large-section tunnel in an urban space provided by the present invention;

[0018] Figure 2 It is a schematic structural diagram of an embodiment of the explosives in the blast holes in the cut area and the auxiliary area of the drill and blast construction method for a large-section tunnel in an urban space provided by the present invention;

[0019] Figure 3 It is a schematic structural diagram of an embodiment of the explosives in the blast holes in the perimeter area of the drill and blast construction method for a large-section tunnel in an urban space provided by the present invention;

[0020] Figure 4 It is a schematic flow diagram of an embodiment of the drill and blast construction method for a large-section tunnel in an urban space provided by the present invention;

[0021] Figure 5 For Figure 4 It is a detailed flow diagram of step S40 in

[0022] Figure 6 For Figure 4 It is a detailed flow diagram of step S60 in

[0023] Explanation of the reference numerals in the drawings:

[0024] 10, face; 20, cut area; 30, auxiliary area; 40, perimeter area; 50, blast hole; 51, non-electric detonator; 52, bulk emulsion explosive; 53, plugging material; 54, detonator; 55, stick emulsion explosive; 56, explosive wire.

[0025] The realization of the objectives, functional features and advantages of the present invention will be further described in conjunction with the embodiments with reference to the drawings. Detailed Embodiments

[0026] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0027] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components in a certain specific posture. If the specific posture changes, the directional indication will also change accordingly.

[0028] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features limited to "first" and "second" may explicitly or implicitly include at least one of the features. In addition, if "and / or" or "and / or" appears in the full text, its meaning includes three parallel solutions. Taking "A and / or B" as an example, it includes solution A, solution B, or solutions that satisfy both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0029] When the existing tunnel drilling and blasting construction method is applied to large-section tunnels, due to the large area of ​​the face, it usually involves a variety of geological conditions. The blasting effects of the same blasting hole arrangement scheme in different geological conditions are quite different. The same arrangement scheme for multiple blasting holes will lead to inaccurate control of the blasting range and effect, and it is easy to have an uneven blasting surface, affecting the construction quality and aesthetics of the tunnel. Secondly, in terms of the release and transmission of blasting energy, the existing drilling and blasting method often releases the energy generated by the blasting in a concentrated manner, causing greater disturbance to the surrounding rock, easily destroying the stability of the surrounding rock, increasing construction safety risks, and easily causing a greater impact on the surrounding environment.

[0030] The present invention provides a drilling and blasting construction method for a large-section tunnel in an urban space, comprising the following steps:

[0031] S10: Conducting geological exploration on the tunnel face to obtain geological conditions;

[0032] See also Figure 4 , Figure 4 A flow chart of an embodiment of a drilling and blasting construction method for a large-section tunnel in an urban space provided by the present invention; the drilling and blasting construction method for a large-section tunnel in an urban space proposed by the present invention, before blasting, obtains geological conditions such as the rock and soil layer composition, groundwater distribution and ground stress of the heading face 10 by conducting geological exploration on the geological body within the blasting range of the tunnel, so as to provide data support for the subsequent blasting model according to the geological conditions.

[0033] S20: Divide the heading face into a cut area located in the middle of the heading face, an auxiliary area located outside the cut area, and a perimeter area located outside the auxiliary area and at the edge of the heading face;

[0034] Please refer to Figure 1 , Figure 1 , which is a schematic structural diagram of an embodiment of the drilling and blasting construction method for large-section tunnels in urban spaces provided by the present invention. For large-section tunnels, the area of the heading face 10 is relatively large, and it is necessary to divide the heading face 10 according to its shape. The heading face 10 is divided into a cut area 20, an auxiliary area 30, and a perimeter area 40 from the inside to the outside. The cut area 20 is located in the very middle of the heading face 10 and can take the lead in blasting to form a free face. The auxiliary area 30 is an area within a certain range outside the cut area 20 and is blasted after the cut area 20 is blasted, playing a role in expanding the cut effect and assisting in rock breaking. The perimeter area 40 located at the edge of the heading face 10 is used to accurately control the blasting contour and improve the blasting accuracy.

[0035] S30: Establish a blasting model based on the geological conditions;

[0036] Establishing a blasting model based on the geological conditions can determine the corresponding blasting equivalent for different geological conditions, and analyze the propagation path and attenuation law of blasting vibration in different strata through the simulated blasting process of the blasting model, ensuring that similar blasting effects can be obtained under different strata conditions, making the blasting surface more neat, and providing a basis for formulating the layout plan of the subsequent blast hole group 50. It should be noted that the blasting model is established based on computer simulation software in the prior art.

[0037] S40: Determine the layout plan of the blast hole group and the selection plan of explosives according to the blasting model; wherein, the blast hole group includes a plurality of blast holes respectively arranged in the cut area, the auxiliary area, and the perimeter area;

[0038] It can be understood that the selection plan of explosives includes types such as bulk emulsion explosive, strip emulsion explosive 55, detonator 54, non-electric detonator 51, blasting wire 56, plugging material 53, etc. and their mutual combinations. The layout plan of the blast hole group 50 includes the layout plan of the blast holes 50 in the cut area 20, the layout plan of the blast holes 50 in the auxiliary area 30, and the layout plan of the blast holes 50 in the perimeter area 40. The maximum charge amount, hole diameter, hole depth and other parameters of the blast holes 50 in different partitions are determined according to the required blasting equivalent obtained through the analysis of the blasting model, which can accurately set the blasting effect of each blast hole 50, thereby more precisely controlling the blasting range and blasting effect, making the blasting surface smoother and facilitating precise construction on site.

[0039] S50: Use an automatic rock drill to drill a plurality of the blast holes in the cut area, the auxiliary area, and the perimeter area respectively according to the layout plan of the blast hole group;

[0040] By inputting the layout plan of each blast hole 50 into the automatic rock drill, the automatic rock drill, through its own high-precision positioning system and multi-degree-of-freedom drill boom, drills a plurality of blast holes 50 in sequence on the tunnel face 10 according to parameters such as the preset position coordinates, the aperture, the hole depth, and the angle of the blast hole 50. The hole-forming quality is good, the drilling accuracy is high, and the construction mechanization degree is high.

[0041] S60: Conduct millisecond-delay blasting on the plurality of blast holes in the cut area, the auxiliary area, and the perimeter area in sequence.

[0042] In millisecond-delay blasting, the blast hole 50 groups are detonated in sequence according to millisecond-level time differences. The blast holes 50 in the cut area 20 are detonated first to form a free face, and the broken rock mass provides an energy release channel for subsequent blasting; after a few milliseconds of delay, the blast holes 50 in the auxiliary area 30 are detonated. With the help of the formed free face, the rock is more easily broken and thrown outwards; after a few more milliseconds of delay, the blast holes 50 in the perimeter area 40 are detonated, and the rock mass strength weakened by the previous two blasts is utilized to accurately cut the surrounding rock.

[0043] The drill-and-blast construction method for large-section tunnels in urban spaces proposed by the present invention divides the tunnel face 10 with a relatively large area into a cut area 20, an auxiliary area 30, and a perimeter area 40, establishes a blasting model based on the specific geological conditions of the tunnel face 10, and simulates the blasting process according to the blasting model, so as to accurately set the layout plans of the blast holes 50 in different zones, thereby more precisely controlling the blasting range and blasting effect, making the blasting surface smoother, and effectively improving the blasting construction accuracy. By conducting millisecond-delay blasting on the blast holes 50 in the cut area 20, the auxiliary area 30, and the perimeter area 40 in sequence, the energy generated by the blasting of each blast hole 50 is evenly released and orderly transmitted from the inside to the outside along the tunnel face 10, and it is possible to realize the blasting construction of large-section tunnels with a tunnel face 10 area exceeding 300 square meters, avoid excessive disturbance to the surrounding rock due to a single full-area blasting of the tunnel face 10, and effectively reduce the disturbance to the surrounding environment, so as to ensure the stability of the surrounding rock and the construction safety of the tunnel in urban spaces.

[0044] In one embodiment, step S40 includes:

[0045] S41: Determine the type of the explosive according to the blasting model;

[0046] S42: Determine the maximum charge amount of each blast hole according to the type of the explosive;

[0047] S43: Determine the hole diameter of the blast hole according to the maximum charge amount.

[0048] S44: Calculate the first spacing, second spacing, and third spacing of the blast holes respectively according to the hole diameter; wherein, the first spacing is the spacing between two adjacent blast holes 50 in the cut area 20, the second spacing is the spacing between two adjacent blast holes 50 in the auxiliary area 30, and the third spacing is the spacing between two adjacent blast holes 50 in the perimeter area 40.

[0049] S45: Determine the depths of the blast holes in the cut area, the auxiliary area, and the perimeter area respectively according to the first spacing, the second spacing, and the third spacing.

[0050] Please refer to Figure 5 , Figure 5 is Figure 4 a detailed process schematic diagram of step S40 in

[0051] In one embodiment, step S41 includes:

[0052] S41: Determine the types of the explosives in the blast holes located in the cut area and the auxiliary area according to the blast model.

[0053] Please refer to Figure 2 , Figure 2Schematic diagram of the structure of an explosive in the blasting hole 50 in the cut area 20 and the auxiliary area 30 of the drilling and blasting construction method for large-section tunnels in urban spaces provided by the present invention; the explosive in the blasting hole 50 in the cut area 20 and the auxiliary area 30 is selected as bulk emulsion explosive, non-electric detonator 51 and detonator. 54, detonator. 54 and non-electric detonator 51 are loaded at the bottom of the blasting hole 50, the bulk emulsion explosive is loaded into a plastic tube, and the plug 53 seals the orifice of the blasting hole 50 to prevent the gas leakage when the bulk emulsion explosive explodes through the plug 53.

[0054] S41: Determine the type of the explosive in the blasting hole in the peripheral area according to the blasting model.

[0055] Please refer to Figure 3 , Figure 3 Schematic diagram of the structure of an explosive in the blasting hole 50 in the peripheral area 40 of the drilling and blasting construction method for large-section tunnels in urban spaces provided by the present invention; the explosive in the blasting hole 50 in the peripheral area 40 is selected as strip emulsion explosive 55, non-electric detonator 51 and blasting wire 56. The number of strip emulsion explosives 55 is three. The non-electric detonator 51 and the strip emulsion explosive 55 are loaded at the bottom of the blasting hole 50, led out of the blasting hole 50 through the blasting wire 56, and the orifice of the blasting hole 50 is sealed by the plug 53 to prevent the gas leakage when the strip emulsion explosive 55 explodes through the plug 53.

[0056] In an embodiment, the filling length of the bulk emulsion explosive is 2m; the weight of the detonator is 20g or 25g; the specification of the blasting wire is 40g / m; the specification of the strip emulsion explosive is φ32mm, and the length of the strip emulsion explosive is 200mm; the length of the plug 53 is 0.8m to 1m.

[0057] In an embodiment, the aperture of the blasting hole in the cut area is 89mm to 102mm, and the aperture of the blasting hole in the auxiliary area and the peripheral area ≥50mm.

[0058] It should be noted that in the traditional drilling and blasting method, the layout scheme of the blasting hole 50 usually adopts the idea of "short advance, dense holes, and weak blasting". The aperture of the blasting hole 50 generally does not exceed 40mm. In the drilling and blasting construction method for large-section tunnels in urban spaces proposed by the present invention, the aperture of each blasting hole 50 in the cut area 20 is 89mm to 102mm, and the aperture of a single blasting hole 50 in the auxiliary area 30 and the peripheral area 40 is not less than 50mm, so as to increase the maximum charge amount of the blasting hole 50, thereby increasing the blasting range of each blasting hole 50, reducing the number of arrangements of the blasting hole 50, and effectively increasing the blasting propulsion depth of a single heading face 10, thereby greatly improving the drilling and blasting construction efficiency.

[0059] It should be noted that the maximum charge of each blast hole 50 is determined according to the formula PPV = 644(R / W 1 / 2 ) -1.22 Calculated, where PPV is taken as 25 mm / s, R is the distance between the position of the blast hole 50 and the edge of the blasting range, and W is the maximum charge MIC of the blast hole 50. In this construction method, the minimum value of the maximum charge of each blast hole 50 exceeds 10 kg, so the aperture of the blast hole 50 is designed to be ≥50 mm.

[0060] In one embodiment, the first spacing ≥1 m; the second spacing ≥1 m; the third spacing ≥0.6 m.

[0061] Furthermore, in the traditional drill and blast method, the spacing of the blast holes 50 is usually 0.7 m to 0.8 m. In the drill and blast construction method for large-section tunnels in urban spaces proposed by the present invention, the spacing between the blast holes 50 in the cut area 20 and the auxiliary area 30 is not less than 1 m, and the spacing between the blast holes 50 in the perimeter area 40 is not less than 0.6 m. By increasing the blasting range of a single blast hole 50, the number of blast holes 50 arranged is greatly reduced, and the amount of explosives consumed per unit area of the heading face 10 is effectively reduced, effectively saving the amount of explosives used and reducing the construction cost.

[0062] It should be noted that the drilling depth of each blast hole 50 is jointly determined according to the spacing and the maximum charge of the blast hole 50. The drilling depth L = L s +L c , the stemming length L s is not less than the spacing of the blast hole 50, and the charging length L c = MIC / 1.59, where MIC is the maximum charge of the blast hole 50. Therefore, the depth range of each blast hole 50 is 5.5 m to 6 m.

[0063] In one embodiment, step S60 includes:

[0064] S61: Carry out millisecond blasting on the multiple blast holes in the cut area in sequence from the middle to the edge of the heading face;

[0065] S62: Carry out millisecond blasting on the multiple blast holes in the auxiliary area in sequence from the middle to the edge of the heading face;

[0066] S63: Carry out millisecond blasting on the multiple blast holes in the perimeter area in sequence from the middle to the edge of the heading face.

[0067] Please refer to Figure 6 , Figure 6 For Figure 4Schematic diagram of the refined process of step S60. Multiple blast holes 50 in 50 groups of blast holes are arranged at intervals in sequence from the middle to the edge of the heading face 10. When performing millisecond-delay blasting on the multiple blast holes 50, millisecond-delay blasting is respectively carried out on the multiple blast holes 50 in each partition, and at the same time, millisecond-delay blasting is also carried out on the cut area 20, the auxiliary area 30, and the perimeter area 40 as a whole. After the blast holes 50 in the cut area 20 are blasted, the blast holes 50 in the auxiliary area 30 are blasted, and after the blast holes 50 in the auxiliary area 30 are blasted, the blast holes 50 in the perimeter area 40 are blasted. First, millisecond-delay blasting is carried out on the multiple blast holes 50 in the cut area 20, and they are detonated in sequence with a millisecond-level time difference, so that the energy is concentrated and released to break the core rock mass of the heading face 10 and form a free face. Subsequently, millisecond-delay blasting is carried out on the multiple blast holes 50 in the auxiliary area 30. By using the formed free face, the rock is more easily broken and thrown outwards, expanding the cut effect and weakening the integrity of the surrounding rock mass. Finally, millisecond-delay blasting is carried out on the multiple blast holes 50 in the perimeter area 40, and the precision-controlled smooth blasting technology is adopted to make the flatness of the excavation surface meet the design requirements and reduce the phenomenon of overbreak and underbreak. This partitioned millisecond-delay blasting method enables the blasting energy to be transmitted orderly from the inside to the outside along the heading face 10, effectively reducing the disturbance to the surrounding environment, ensuring the stability of the surrounding rock of the tunnel and the construction safety, and at the same time optimizing the blasting effect and improving the construction efficiency and quality.

[0068] In one embodiment, step S61 includes:

[0069] S611: Load electric detonators into the blast hole located in the very middle of the cut area;

[0070] S612: Load non-electric detonators into the remaining several blast holes;

[0071] S613: Connect the electric detonator and each adjacent non-electric detonator with detonating fuse, and connect each non-electric detonator with its adjacent non-electric detonator from the middle to the edge of the cut area;

[0072] S614: Detonate the electric detonator so that several non-electric detonators are detonated in sequence from the middle to the edge of the cut area.

[0073] Further, by loading electric detonators into the blasting holes 50 at the very center of the cut area 20, with the electric detonators serving as the initiation source, the electric detonators are arranged at the very center of the cut area 20, enabling the blasting energy to evenly disperse in all directions and preliminarily fragmenting the core rock mass. By loading non-electric detonators 51 into the remaining blasting holes 50, and utilizing the excellent millisecond-level delay performance of the non-electric detonators 51, they can be detonated in sequence according to the preset time difference, cooperating with the electric detonators to achieve the millisecond-delay blasting effect. The electric detonators and the adjacent non-electric detonators 51 are connected through detonating cords, and the non-electric detonators 51 are connected in sequence from the center to the edge of the cut area 20, forming a network for orderly initiation from the inside out, ensuring that the blasting energy is released along the designed path, gradually fragmenting the rock mass, and reducing energy waste and unnecessary disturbance to the surrounding rock. It should be noted that the blasting holes 50 in the auxiliary area 30 and the peripheral area 40 are also loaded with non-electric detonators 51, and are connected to the non-electric detonators 51 in the cut area 20 through detonating cords along the direction from the center to the edge of the tunnel face 10. After the electric detonator at the very center of the cut area 20 is detonated, all the remaining non-electric detonators 51 on the entire tunnel face 10 are detonated in sequence, realizing the millisecond-delay blasting from the cut area 20, the auxiliary area 30 to the peripheral area 40.

[0074] In one embodiment, after step S60, the drill-and-blast construction method for large-section tunnels in urban spaces proposed by the present invention further includes:

[0075] S70: Using a vibration measuring instrument to measure the peak particle vibration velocity and the overpressure of the air shock wave in the tunnel during the blasting process, so as to obtain the peak particle vibration velocity value and the overpressure value of the air shock wave respectively.

[0076] S80: Dynamically adjusting the blasting model based on the peak particle vibration velocity value and the overpressure value of the air shock wave.

[0077] It should be noted that by setting a vibration measuring instrument to capture the change in the vibration velocity of rock mass particles in real time at the moment of blasting, accurately recording the peak particle vibration velocity value and the overpressure value of the air shock wave, and then comparing the peak particle vibration velocity value and the overpressure value of the air shock wave with the blasting model, the blasting model is dynamically adjusted, enabling the continuous optimization of the blasting model and accurately adapting to the actual construction conditions.

[0078] In one embodiment, step S80 includes:

[0079] S81: Establishing the blasting model based on the geological conditions;

[0080] S82: Conducting simulated blasting according to the blasting model to obtain the predicted value of the peak particle vibration velocity and the predicted value of the overpressure of the air shock wave;

[0081] S83: Compare the peak particle vibration velocity value and the predicted peak particle vibration velocity value to obtain the peak particle vibration velocity deviation value, and compare the air shock overpressure value and the predicted air shock overpressure value to obtain the air shock overpressure deviation value;

[0082] S84: Modify the blasting model according to the air shock overpressure deviation value and the air shock overpressure deviation value.

[0083] Further, the initial blasting model is established based on the geological conditions. The initial blasting model is only established according to the geological conditions obtained from geological exploration, which may be different from the actual geological conditions, resulting in deviations between the predicted peak particle vibration velocity value and the predicted air shock overpressure value obtained through simulated blasting and the actual situation. By comparing the peak particle vibration velocity value obtained during the actual blasting process with the predicted peak particle vibration velocity value, the peak particle vibration velocity deviation value is obtained, and by comparing the air shock overpressure value with the predicted air shock overpressure value, the air shock overpressure deviation value is obtained, so as to facilitate the modification of the blasting model according to the deviation value, make the blasting model more consistent with the actual blasting situation, provide more scientific guidance for subsequent blasting operations, and ensure the safety, efficiency and accuracy of construction.

[0084] In one embodiment, before step S60, the drill-and-blast construction method for large-section tunnels in urban space proposed by the present invention further includes:

[0085] S59: Install advanced small pipe supports outside the peripheral area.

[0086] It can be understood that before blasting construction, advanced small pipe supports are installed outside the peripheral area 40 to reinforce the rock mass at the edge of the blasting range of the tunnel, improve the stability of the rock mass around the tunnel, reduce the disturbance of the blasting to the surrounding rock mass, effectively control the deformation of the tunnel excavation surface, and ensure construction safety.

[0087] In one embodiment, after step S60, the drill-and-blast construction method for large-section tunnels in urban space proposed by the present invention further includes:

[0088] S90: Monitor the air quality in the tunnel;

[0089] S100: Ventilate the tunnel until the air quality in the tunnel meets the preset requirements.

[0090] It should be noted that after the blasting construction of a heading face 10 is completed, a gas detector is used to monitor the air quality in the tunnel after blasting, specifically including monitoring the concentrations of gases such as oxygen, methane, hydrogen sulfide, carbon monoxide, and radon, and ventilating the tunnel to make the air velocity in the tunnel not less than 0.5 m / s until the air quality monitoring data shows that the concentrations of harmful gases and the dust content are reduced to within the preset safety standard range, ensuring that construction workers can safely enter the tunnel to continue subsequent operations.

[0091] The above description is only an exemplary embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformation made under the technical concept of the present invention by using the content of the specification and drawings of the present invention, or any direct / indirect application in other related technical fields is included in the patent protection scope of the present invention.

Claims

1. A drilling and blasting construction method for a large-section tunnel in an urban space, characterized in that: include: Conducting geological exploration on the tunnel face to obtain geological conditions; Dividing the tunnel face into a grooved area located in the middle of the tunnel face, an auxiliary area located outside the grooved area, and a peripheral area located outside the auxiliary area and at the edge of the tunnel face; Establishing a blasting model based on the geological conditions; Determine the arrangement scheme of the blasting hole group and the selection scheme of the explosives according to the blasting model; wherein the blasting hole group includes a plurality of blasting holes respectively arranged in the cutting area, the auxiliary area and the peripheral area; Using an automatic rock drilling vehicle to drill a plurality of blasting holes in the cutout area, the auxiliary area and the peripheral area respectively according to the arrangement plan of the blasting hole group; Micro-difference blasting is performed on the plurality of blasting holes in the cutting area, the auxiliary area and the peripheral area in sequence.

2. The drilling and blasting construction method for a large-section tunnel in an urban space as claimed in claim 1, characterized in that: The step of determining the arrangement scheme of the blasting hole group and the selection scheme of the explosives according to the blasting model comprises: Determining the type of the explosive according to the blasting model; Determining the maximum charge amount of each blasting hole according to the type of the explosive; Determining the diameter of the blasting hole according to the maximum charge amount; The first spacing, the second spacing and the third spacing of the blasting holes are calculated according to the apertures; wherein the first spacing is the spacing between two adjacent blasting holes in the cutout area, the second spacing is the spacing between two adjacent blasting holes in the auxiliary area, and the third spacing is the spacing between two adjacent blasting holes in the peripheral area; The depths of the blasting holes in the cutting area, the auxiliary area, and the peripheral area are determined according to the first spacing, the second spacing, and the third spacing, respectively.

3. The drilling and blasting construction method for a large-section tunnel in an urban space as claimed in claim 2, characterized in that: The step of determining the type of the explosive according to the blasting model comprises: Determine the types of the explosives in the blasting holes in the cutout area and the auxiliary area according to the blasting model; the explosives in the blasting holes in the cutout area and the auxiliary area are selected from bulk emulsion explosives, non-electric detonators and initiators, and are sealed with plugging materials; The type of the explosive in the blasting hole in the peripheral area is determined according to the blasting model; the explosive in the blasting hole in the peripheral area is selected from strip emulsion explosives, non-electric detonators and explosive wires, and is sealed with the plugging material.

4. The drilling and blasting construction method for a large-section tunnel in an urban space as claimed in claim 3, characterized in that: The filling length of the bulk emulsion explosive is 2m; the weight of the detonator is 20g or 25g; the specification of the explosive line is 40g / m; the specification of the strip emulsion explosive is φ32mm, and the length of the strip emulsion explosive is 200mm; the length of the plug is 0.8m to 1m.

5. The drilling and blasting construction method for a large-section tunnel in an urban space as claimed in claim 2, characterized in that: The diameter of the blasting holes located in the groove area is 89 mm to 102 mm, and the diameter of the blasting holes located in the auxiliary area and the peripheral area is ≥50 mm.

6. The drilling and blasting construction method for a large-section tunnel in an urban space as claimed in claim 2, characterized in that: The first spacing is ≥1m; the second spacing is ≥1m; and the third spacing is ≥0.6m.

7. The drilling and blasting construction method for a large-section tunnel in an urban space according to any one of claims 1 to 6, characterized in that: The step of sequentially performing micro-difference blasting on the plurality of blasting holes in the cutout area, the auxiliary area and the peripheral area comprises: The plurality of blasting holes in the cutout area are sequentially blasted with slight differences from the middle to the edge of the tunnel face; The plurality of blasting holes in the auxiliary area are sequentially blasted with slight differences from the middle to the edge of the tunnel face; The plurality of blasting holes in the peripheral area are blasted sequentially with slight differences from the middle to the edge of the tunnel face.

8. The drilling and blasting construction method for a large-section tunnel in an urban space as claimed in claim 7, characterized in that: The step of sequentially blasting the plurality of blasting holes in the cutout area from the middle to the edge of the tunnel face with slight differences comprises: Filling electric detonators in the blasting hole located in the middle of the cut zone; Filling the remaining blasting holes with non-electric detonators; Connecting the electric detonator and each of the adjacent non-electric detonators with a detonating cord, and connecting each of the non-electric detonators with the adjacent non-electric detonators from the middle to the edge of the cutout area; The electric detonator is detonated so that a plurality of the non-electric detonators are detonated in sequence from the middle to the edge of the groove area.

9. The drilling and blasting construction method for a large-section tunnel in an urban space according to any one of claims 1 to 6, characterized in that: After the step of sequentially performing micro-difference blasting on the plurality of blasting holes in the cutout area, the auxiliary area and the peripheral area, the method further comprises: The peak vibration velocity of the particles and the overpressure of the air shock wave in the tunnel during the blasting process are measured by using a vibration meter to obtain the peak vibration velocity value of the particles and the overpressure value of the air shock wave respectively; The blasting model is dynamically adjusted according to the particle peak vibration velocity value and the air shock wave overpressure value.

10. The drilling and blasting construction method for a large-section tunnel in an urban space as claimed in claim 9, characterized in that: The step of dynamically adjusting the blasting model according to the particle peak vibration velocity value and the air shock wave overpressure value comprises: Establishing the blasting model based on the geological conditions; Performing a simulated blasting according to the blasting model to obtain a predicted value of the particle peak vibration velocity and a predicted value of the air shock wave overpressure; Comparing the particle peak vibration velocity value with the particle peak vibration velocity prediction value to obtain a particle peak vibration velocity deviation value, and comparing the air shock wave overpressure value with the air shock wave overpressure prediction value to obtain an air shock wave overpressure deviation value; The blasting model is modified according to the air shock wave overpressure deviation value and the air shock wave overpressure deviation value.

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