A method for shallow hole blasting excavation of front and rear pilot holes of large deep buried circular working well under hard rock condition

Abstract

The application discloses a large deep-buried circular working well front and rear pilot hole shallow hole blasting excavation method under hard rock conditions, and belongs to the technical field of hard rock circular working well blasting. First, the site is explored, and a front and rear pilot hole and a working well structure building information model is established according to design drawings. Arch arrangement is performed according to design requirements, and an initial support arch building information model is established according to the pilot hole section size. The application has the beneficial effect that the tunnel excavation contour and the initial support arch installation position are accurately simulated through the building information model technology, the first curved surface blasting excavation range and depth are determined, the drilling operation conditions are combined, the drilling arrangement, angle and depth are accurately simulated through the building information model, the excavation quality is accurately controlled, the overbreak and underbreak phenomenon caused by the curved surface blasting is effectively reduced, the blast hole arrangement and depth are accurately simulated, the blasting quality is controlled, the overbreak and underbreak phenomenon is reduced, and the construction efficiency is effectively improved.

Description

Technical Field

[0001] This invention relates to the field of blasting for circular working shafts in hard rock, and is based on a shallow-hole blasting excavation method for the front and rear pilot tunnels of large, deeply buried circular working shafts under hard rock conditions. Background Technology

[0002] Shallow hole blasting, commonly known as "shallow-hole blasting" or "open-pit shallow-hole blasting," refers to blasting operations using boreholes with a diameter of 50mm or less and a depth of 5m or less when excavating and secondary crushing large blocks of rock or ore. General shallow hole blasting refers to simple shallow hole blasting operations in uncomplicated environments, where appropriate explosive dosage is used, and no additional protective measures are required. Urban shallow hole blasting refers to operations in densely populated areas where measures are taken to control harmful effects, involving excavation and secondary crushing of large blocks using shallow hole blasting methods.

[0003] The design scheme for the pilot tunnels before and after the working shaft adopts shallow hole blasting construction. Each blasting excavation advance is the distance between two arch frames. Due to the large diameter of the pilot tunnel, step shallow hole blasting excavation is required. When excavating the upper pilot tunnel, the waste generated when breaking the tunnel portal needs to be piled up to form a working platform. The working shaft is also circular, and there is an angle between the advance direction of the pilot tunnel and the circular shaft wall. The working area on top of the waste pile is limited, making it difficult to carry out blasting hole drilling construction according to the direction of the line axis. Moreover, the depth and position of the blasting holes should be adjusted according to the relative position relationship of the blast holes. Otherwise, the quality of blasting construction is difficult to guarantee, and it is easy to cause over-excavation or under-excavation of the tunnel. Summary of the Invention

[0004] The purpose of this invention is to provide a shallow-hole blasting excavation method for the front and rear pilot tunnels of a large, deeply buried circular working shaft under hard rock conditions. This method addresses the problems mentioned in the background art, such as the working shaft being circular, the pilot tunnel's drilling direction having an angle with the circular shaft wall, the limited working area at the top of the slag heap, the difficulty in drilling blasting holes along the line axis, and the need to adjust the depth and position of the blasting holes according to their relative positions to ensure blasting quality and prevent over- or under-excavation of the tunnel.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a method for shallow hole blasting excavation of the front and rear pilot tunnels of a large, deeply buried circular working well under hard rock conditions, characterized by the following steps.

[0006] S1. First, conduct on-site exploration and establish a structural building information model of the front and rear pilot tunnels and working shafts according to the design drawings;

[0007] S2. Arrange the arch frames according to the design requirements and establish the initial support arch frame building information model based on the cross-sectional dimensions of the pilot tunnel, and complete the arch frame layout simulation.

[0008] S3. In accordance with the requirements of shallow hole blasting, and based on the previously arranged arch frame position, determine the excavation range for the first blast and establish a building information model of the rock mass to be blasted for the first time.

[0009] S4. Based on the working range formed by the on-site slag heap, determine the optimal angle for blasting drilling in the upper pilot tunnel, and improve the simulation of blasting drilling spacing and depth according to the predetermined angle;

[0010] S5. Extract information such as the angle, depth, and location of blasting boreholes from the model to provide on-site implementation information;

[0011] S6. Based on the distance between the pilot tunnel blasting boreholes, and considering the quantity and power of the explosives required for the blasting, construct and arrange the layout and conduct simulation tests.

[0012] Furthermore, based on a shallow-hole blasting excavation method for the front and rear pilot tunnels of a large, deeply buried circular working shaft under hard rock conditions, the method is characterized in that: in step S1, establishing the structural building information model of the front and rear pilot tunnels and the working shaft includes;

[0013] Import the front view, top view, side view, and site plan of the design blueprint into the software, and build the working shaft and front and rear pilot tunnel models according to the design dimensions and structure to accurately simulate the positional relationship between the pilot tunnel (curved tunnel) and the working shaft.

[0014] Furthermore, based on a shallow-hole blasting excavation method for the front and rear pilot tunnels of a large deep-buried circular working shaft under hard rock conditions, the method is characterized in that: in step S2, the arch frame is arranged according to the design requirements and an initial support arch frame building information model is established according to the cross-sectional dimensions of the pilot tunnel, and the arrangement simulation of the arch frame is completed.

[0015] The excavation face of the circular working shaft is a curved surface, which is not perpendicular to the axis of the front and rear pilot tunnels. This results in the initial support arch frame being different from the circular arch frame of the design standard cross section. Based on the shape of the working face and the installation position of the arch frame, each arch frame within a certain excavation advance range (within a 6m range of the line centerline length) is accurately simulated and arranged as close as possible to the designed spacing.

[0016] Furthermore, based on a method for shallow-hole blasting excavation of the front and rear pilot tunnels of a large deep-buried circular working shaft under hard rock conditions, the method is characterized in that: in step S3, according to the requirements of shallow-hole blasting, the initial blasting excavation range is determined according to the previously arranged arch frame position, and the building information model of the initial blasting rock mass is established, including:

[0017] The scope of a single blast is the space required for the installation of two arch frames. Based on this principle, the rock mass model that needs to be blasted for the first time is accurately simulated.

[0018] Furthermore, based on a shallow-hole blasting excavation method for the front and rear pilot tunnels of a large, deeply buried circular working well under hard rock conditions, the method is characterized in that: in step S4, the optimal angle for blasting drilling of the upper pilot tunnel is determined in conjunction with the working range formed by the on-site muck, and the blasting drilling spacing and depth simulation is improved according to the predetermined angle.

[0019] Because the pilot tunnel has a large diameter, the excavated debris from breaking the tunnel entrance needs to be piled up to form a working platform during the excavation of the upper pilot tunnel. The working shaft is also circular, and there is an angle between the pilot tunnel's advance direction and the shaft wall. The working area at the top of the debris pile is limited, making it difficult to carry out blasting hole drilling along the line axis. Therefore, it is necessary to determine the optimal angle for blasting drilling operations. Based on the drilling operation area formed by the debris pile, an optimal drilling angle is selected. According to this angle, the drilling spacing, and the rock mass model for blasting determined in S3, the depth of each blasting hole is determined.

[0020] Furthermore, based on a shallow-hole blasting excavation method for the front and rear pilot tunnels of a large, deeply buried circular working well under hard rock conditions, the method is characterized in that: in step S5, information such as the blasting borehole angle, depth, and location are extracted from the model to provide information for on-site implementation;

[0021] Using the software's detailed table function, information such as the angle, depth, and location of blasting boreholes is extracted and provided to the site and surveying team for construction operations.

[0022] Furthermore, the boreholes are arranged in multiple rows with internal empty holes, and the pre-splitting boreholes adopt an intermittent, uncoupled charging structure.

[0023] Compared with the prior art, the beneficial effects of the present invention are:

[0024] (1) This method is based on a shallow hole blasting excavation method for the front and rear pilot tunnels of a large deep-buried circular working shaft under hard rock conditions. By using building information modeling technology, the tunnel excavation outline and the initial support arch installation position are accurately simulated to determine the range and depth of the first curved surface blasting excavation. Combined with the on-site drilling operation conditions, the drilling layout, angle and depth are accurately simulated through building information modeling to accurately control the excavation quality and effectively reduce the occurrence of over-excavation and under-excavation caused by curved surface blasting. The method accurately simulates the layout and depth of the blast holes, controls the blasting quality, reduces the occurrence of over-excavation and under-excavation, and effectively improves the construction efficiency.

[0025] (2) This method is based on a shallow-hole blasting excavation method for the front and rear pilot tunnels of a large, deep-buried circular working well under hard rock conditions. It adopts double-row pre-splitting blasting to the design bottom elevation to form a vibration isolation fracture zone. The inner blast holes are not loaded with explosives, which plays the role of reducing vibration, increasing the free face and increasing the range of the fracture zone. The pre-splitting blast holes adopt an intermittent uncoupled charging structure. At the same time, a second part is constructed. It can be seen that the first part cuts out the slot to create a free face for the subsequent blasting. The blasting adopts a continuous charging structure at the bottom of the hole. The empty hole in the middle does not carry explosives and plays the role of a free face. After the perimeter pre-splitting fracture zone is formed and the free face is created by the first part of the slot, the second part is constructed. According to the thickness of the rock layer of the foundation pit, in order to ensure the blasting effect and reduce the impact of blasting on the surrounding buildings and environment, the foundation pit blasting needs to be carried out in layers and sections. It can reduce the occurrence of over-excavation and under-excavation by accurately simulating the drilling layout, and reduce the risks that may occur during the trimming and over-square process.

[0026] (3) This method is based on a shallow hole blasting excavation method for the front and rear pilot tunnels of a large deep-buried circular working well under hard rock conditions. By comparing the pre-splitting + loosening blasting construction with loosening blasting, the damage to the continuous wall and surrounding buildings caused by loosening blasting can be effectively reduced. At the same time, a fracture surface is generated at the junction with the continuous wall after pre-splitting blasting, forming a flat base surface, which provides favorable conditions for the quality of the structural waterproofing membrane laying. In terms of construction period, cost, safety and quality, the use of pre-splitting + loosening blasting is more reasonable than the use of loosening blasting alone. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the process flow structure of the present invention;

[0028] Figure 2 This is a schematic diagram of the explosive structure of the present invention;

[0029] Figure 3 This is a schematic diagram of the explosive charging structure with perforated holes according to the present invention;

[0030] Figure 4 This is a schematic diagram of the drilling simulation structure of the present invention;

[0031] Figure 5 This is a schematic diagram illustrating the key operational points of the present invention;

[0032] Figure 6 This is a schematic diagram of the explosive charge parameters structure of the present invention;

[0033] Figure 7 This is a schematic diagram of the charging structure parameters for each borehole of the present invention.

[0034] Figure 8 This is a schematic diagram of the economic benefit analysis structure of the present invention. Detailed Implementation

[0035] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] Example 1, as Figure 1 and Figure 5 As shown, a shallow-hole blasting excavation method for the front and rear pilot tunnels of a large, deeply buried circular working shaft under hard rock conditions is characterized by the following steps;

[0037] S1. First, conduct on-site exploration and establish a structural building information model of the front and rear pilot tunnels and working shafts according to the design drawings;

[0038] S2. Arrange the arch frames according to the design requirements and establish the initial support arch frame building information model based on the cross-sectional dimensions of the pilot tunnel, and complete the arch frame layout simulation.

[0039] S3. In accordance with the requirements of shallow hole blasting, and based on the previously arranged arch frame position, determine the excavation range for the first blast and establish a building information model of the rock mass to be blasted for the first time.

[0040] S4. Based on the working range formed by the on-site slag heap, determine the optimal angle for blasting drilling in the upper pilot tunnel, and improve the simulation of blasting drilling spacing and depth according to the predetermined angle;

[0041] S5. Extract information such as the angle, depth, and location of blasting boreholes from the model to provide on-site implementation information;

[0042] S6. Based on the distance between the pilot tunnel blasting boreholes, and considering the quantity and power of the explosives required for the blasting, construct and arrange the layout and conduct simulation tests.

[0043] By establishing a structural model of the pilot tunnel and working shaft according to the design drawings, then arranging the arch frame according to the design requirements and establishing the initial support arch frame model according to the cross-sectional dimensions of the pilot tunnel, then determining the scope of the first blasting excavation according to the arrangement of the arch frame, and then determining the optimal angle for the blasting drilling operation of the upper pilot tunnel in combination with the scope of the on-site muck. The blasting drilling spacing and depth simulation are improved according to the predetermined angle, and finally the information such as angle, depth and position are extracted from the model for on-site implementation.

[0044] Example 2, as Figure 4 As shown, a shallow-hole blasting excavation method for the front and rear pilot tunnels of a large, deeply buried circular working shaft under hard rock conditions is characterized by the following: In step S1, establishing the structural building information model of the front and rear pilot tunnels and the working shaft includes;

[0045] Import the front view, top view, side view, and site plan of the design blueprint into the software, and build the working shaft and front and rear pilot tunnel models according to the design dimensions and structure to accurately simulate the positional relationship between the pilot tunnel (curved tunnel) and the working shaft; use building information modeling technology to accurately simulate the tunnel excavation outline and the installation position of the initial support arch to determine the range and depth of the first curved surface blasting excavation.

[0046] Example 3, as Figure 4 As shown, a shallow-hole blasting excavation method for the front and rear pilot tunnels of a large, deeply buried circular working shaft under hard rock conditions is characterized by the following: In step S2, the arch frame is arranged according to the design requirements and an initial support arch frame building information model is established based on the cross-sectional dimensions of the pilot tunnel, and the arch frame arrangement simulation is completed.

[0047] The excavation face of the circular working shaft is a curved surface, which is not perpendicular to the axis of the front and rear pilot tunnels. This results in the initial support arch frame differing from the circular arch frame of the design standard cross-section. Based on the shape of the tunnel face and the installation position of the arch frame, each arch frame within a certain excavation advance range (within a 6m range of the line centerline) is precisely simulated and arranged as close to the designed spacing as possible. By arranging the arch frames according to the design requirements and establishing a building information model of the initial support arch frame based on the cross-sectional dimensions of the pilot tunnel, the tunnel excavation outline and the installation position of the initial support arch frame are accurately simulated using building information modeling technology. This determines the range and depth of the first curved surface blasting excavation. Combined with the on-site drilling operation conditions, the layout and depth of the blast holes are accurately simulated to control the blasting quality, reduce over-excavation and under-excavation, and effectively improve construction efficiency.

[0048] Example 4, as Figure 3 and Figure 6 As shown, a shallow-hole blasting excavation method for the front and rear pilot tunnels of a large, deeply buried circular working shaft under hard rock conditions is characterized by the following: In step S3, according to the requirements of shallow-hole blasting, the excavation range of the first blasting is determined based on the previously arranged arch frame position, and a building information model of the rock mass to be blasted for the first time is established.

[0049] The range of a single blast is the space required for the installation of two arch frames. Based on this principle, the rock mass model that needs to be blasted for the first time is accurately simulated. The boreholes adopt a multi-row hole arrangement with an inner row of empty holes. The pre-splitting blast holes adopt an interval-decoupled charge structure.

[0050] Example 5, as Figure 3 and Figure 6 As shown, a shallow-hole blasting excavation method for the front and rear pilot tunnels of a large, deeply buried circular working well under hard rock conditions is characterized by: in step S4, the optimal angle for blasting drilling of the upper pilot tunnel is determined in combination with the working range formed by the on-site muck, and the simulation of the blasting drilling spacing and depth is improved according to the predetermined angle.

[0051] Because the pilot tunnel has a large diameter, the excavated debris from breaking the tunnel entrance needs to be piled up to form a working platform during the excavation of the upper pilot tunnel. The working shaft is also circular, and there is an angle between the pilot tunnel's advance direction and the shaft wall. The working area at the top of the debris pile is limited, making it difficult to carry out blasting hole drilling along the line axis. Therefore, it is necessary to determine the optimal angle for blasting drilling. Based on the drilling area formed by the debris pile, an optimal drilling angle is selected. According to this angle, the drilling spacing, and the rock mass model for blasting determined in S3, the depth of each blasting hole is determined. Down-the-hole drills are used for drilling, with a drill bit diameter of 76mm. The drilling depth is 7.5m (designed based on a rock stratum thickness of 7m), with a double-row hole arrangement and an inner row of empty holes. The pre-splitting blast holes adopt an intermittent uncoupled charging structure. The drilling adopts a vertical hole layout with a hole diameter of 76mm. The resistance line W of the front row of holes is 1.8~2.7m, the hole spacing is a=2~2.7m, and the row spacing is b=1.4~2.2m.

[0052] Example 6, as Figure 2 and Figure 7 As shown, a shallow-hole blasting excavation method for the front and rear pilot tunnels of a large, deeply buried circular working well under hard rock conditions is characterized by: in step S5, extracting information such as the blasting borehole angle, depth, and location from the model to provide information for on-site implementation;

[0053] Using the software's detailed table function, information such as the angle, depth, and location of blasting boreholes is extracted and provided to the site and surveying team for construction operations. Based on rock properties, explosive properties, and unit consumption, a preliminary calculation of q = 0.35–0.5 kg / m³ is performed. A test blast is conducted before the actual blast, and adjustments are made based on lithology, blast monitoring vibration velocity, and blasting effect. The single-hole blast volume is V = a * b * H, and the single-hole charge is Q = q * V. To ensure blasting effectiveness, the charge in the first row of holes is reduced by approximately 10% compared to the main boreholes due to the better free face. The charge in the last row of holes is increased by approximately 10% compared to the main boreholes, considering the constraints imposed by the previous rows, to overcome the suppression from the earlier rows and achieve better blasting results. To ensure the safety of the diaphragm wall and structure, the charge in the side holes near the diaphragm wall can be appropriately reduced.

[0054] Example 7, as Figure 8 As shown, compared with loosening blasting alone, the use of pre-splitting + loosening blasting construction can effectively reduce the damage to the diaphragm wall and surrounding buildings caused by loosening blasting. Simultaneously, the pre-splitting blasting creates a fracture surface at the junction with the diaphragm wall, forming a flat base surface, which provides favorable conditions for the quality of the structural waterproofing membrane installation. In conclusion, considering the construction period, cost, safety, and quality, the use of pre-splitting + loosening blasting is more reasonable than using loosening blasting alone.

[0055] Working principle: First, a structural model of the pilot tunnel and working shaft is established according to the design drawings. Then, the arch frame is arranged according to the design requirements, and an initial support arch frame model is established based on the cross-sectional dimensions of the pilot tunnel. Next, the range of the first blasting excavation is determined according to the arrangement of the arch frame. Then, combined with the range of the on-site muck, the optimal angle for the blasting drilling operation in the upper pilot tunnel is determined. The blasting drilling spacing and depth simulation is improved according to the predetermined angle. Finally, information such as angle, depth, and position is extracted from the model and provided for on-site implementation. The tunnel excavation outline and the installation position of the initial support arch frame are accurately simulated through building information modeling technology to determine the range and depth of the first curved surface blasting excavation. Combined with the on-site drilling operation conditions, the layout and depth of the blast holes are accurately simulated to control the blasting quality, reduce the occurrence of over-excavation and under-excavation, and effectively improve construction efficiency.

[0056] Simultaneously, double-row pre-splitting blasting is employed to reach the design bottom elevation to form a vibration-isolated fracture zone. The inner blast holes are left unloaded, serving to reduce vibration, increase the free face, and expand the fracture zone. The pre-splitting blast holes adopt an intermittent, uncoupled charging structure. A second blast is then performed. This first blast creates a free face for subsequent blasting. The blasting employs a continuous charging structure at the bottom of the hole, with empty holes in the middle serving as the free face. After the perimeter pre-splitting fracture zone is formed and the first blast creates the free face, the second blast is performed. Based on the thickness of the foundation pit's rock strata, to ensure blasting effectiveness and reduce the impact of blasting on surrounding buildings and the environment, the foundation pit blasting needs to be carried out in layers and sections. This allows for precise simulation of the borehole layout, reducing over- and under-excavation phenomena and mitigating potential risks during trimming and over-digging processes.

[0057] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, and is not intended to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions made by those skilled in the art to the technical solution of the present invention do not depart from the essence and scope of the technical solution of the present invention.

Claims

1. A method for shallow-hole blasting excavation of pilot tunnels before and after a large, deeply buried circular working shaft under hard rock conditions, characterized in that: Includes the following steps: S1. First, conduct on-site exploration and establish a structural building information model of the front and rear pilot tunnels and working shafts according to the design drawings; S2. Arrange the arch frames according to the design requirements and establish the initial support arch frame building information model according to the cross-sectional dimensions of the pilot tunnel. Complete the arch frame layout simulation, including: the excavation face of the circular working shaft is a curved surface, which is not perpendicular to the axis of the front and rear pilot tunnels, resulting in the initial support arch frame being different from the circular arch frame of the design standard cross-section. Accurately simulate each arch frame within a certain excavation advance range according to the shape of the working face and the installation position of the arch frame, and arrange them according to the designed spacing. S3. In accordance with the requirements of shallow hole blasting, based on the arch frame position that has been simulated and arranged as described above, determine the excavation range for the first blast and establish a building information model of the rock mass to be blasted for the first time. S4. Based on the working area formed by the on-site slag heap, determine the optimal angle for blasting drilling in the upper pilot tunnel. Improve the simulation of blasting hole spacing and depth according to the determined optimal angle. This includes: Due to the large diameter of the pilot tunnel, when excavating the upper pilot tunnel, it is necessary to use the slag generated when breaking the tunnel entrance to form a working platform. The working shaft is also circular, and there is an angle between the pilot tunnel's advance direction and the shaft wall. The working area at the top of the slag heap is limited, making it difficult to carry out blasting hole drilling construction according to the line axis direction. Therefore, it is necessary to determine the optimal angle for blasting drilling. Based on the drilling working area formed by the slag heap, determine an optimal drilling angle. S5. Extract the angle, depth, and location information of blasting boreholes from the model to provide on-site implementation; S6. Based on the distance between the pilot tunnel blasting boreholes, and considering the quantity and power of the explosives required for the blasting, construct and arrange the layout and conduct simulation tests.

2. The method for shallow-hole blasting excavation of pilot tunnels before and after a large, deeply buried circular working shaft under hard rock conditions, as described in claim 1, is characterized in that: In step S1, establishing the structural architectural information model of the front and rear pilot tunnels and the working shaft includes: Import the front view, top view, side view, and general plan of the design blueprint into the software, and build the working shaft and front and rear pilot tunnel models according to the design dimensions and structure to accurately simulate the positional relationship between the pilot tunnel and the working shaft.

3. The method for shallow-hole blasting excavation of pilot tunnels before and after a large, deeply buried circular working shaft under hard rock conditions, as described in claim 1, is characterized in that: In step S3, according to the requirements of shallow-hole blasting, and based on the previously completed simulated arch frame location, the excavation range for the first blast is determined, and the building information model of the rock mass for the first blast is established, including: The scope of a single blast is the space required for the installation of two arch frames. Based on this principle, the rock mass model that needs to be blasted for the first time is accurately simulated.

4. The method for shallow-hole blasting excavation of pilot tunnels before and after a large, deeply buried circular working shaft under hard rock conditions, as described in claim 1, is characterized in that: In step S5, extracting the angle, depth, and location information of the blasting borehole from the model for on-site implementation includes: Using the software's detailed table function, the angle, depth, and location information of the blasting boreholes are extracted and provided to the site and surveying team for construction operations.

5. The shallow-hole blasting excavation method for the front and rear pilot tunnels of a large, deeply buried circular working shaft under hard rock conditions, as described in claim 4, is characterized in that: The boreholes are arranged in multiple rows with internal empty holes, and the pre-splitting boreholes adopt an intermittent, non-coupled charging structure.

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