Urban sensitive area weak surrounding rock high-efficiency tunneling blasting method

Abstract

The application discloses a kind of city sensitive area weak surrounding rock high efficiency tunneling blasting method, specific steps include S1: using combined wedge slotting form optimization slotting blasting mode, S2: according to the maximum simultaneous detonation number of different types of blast hole under city sensitive area obtained by field trial explosion test, S3: reasonable delay time interval is calculated for different types of blast hole, S4: segmented charging is carried out on peripheral hole using energy-gathering tube cover combined charging device;The city sensitive area weak surrounding rock high efficiency tunneling blasting method, segmented charging is carried out on peripheral hole using energy-gathering tube cover combined charging device, can be applied to the construction of subway tunnel drill-and-blast method in the surrounding rock condition of joint development in city downtown, while effectively controlling blasting vibration velocity, ensure that smooth blasting rock breaking effect will not affect construction progress, reduce construction cost and improve construction efficiency, energy-gathering tube cover structure not only integrates the characteristics of current market energy-gathering tube.

Description

Technical Field

[0001] This invention relates to the field of tunnel blasting technology, specifically to a method for efficient tunnel excavation and blasting in soft surrounding rock in sensitive urban areas. Background Technology

[0002] In recent years, the construction of urban subway tunnels in my country has developed rapidly, but many problems have also been encountered during the construction process. The surrounding environment of urban subway tunnels is very complex, often involving densely packed buildings along the line, proximity to the tunnel, and aging structures. The excavation of subway tunnels can easily disturb the foundations of surrounding buildings, leading to structural damage, uneven ground settlement, and other issues that significantly impact construction safety. In particular, tunnel projects constructed using blasting are inevitably affected by the harmful effects of blasting on their linings, surrounding rock, and adjacent buildings and structures.

[0003] Based on the above description, the following problems exist in the construction of subway tunnels using the drill-and-blast method under complex geological conditions in urban sensitive areas: (1) Due to the constraints of urban sensitive areas, the control of blasting vibration velocity is extremely strict, and the requirements for the amount of single-shot explosive and blasting construction plan are very strict. Existing construction methods often adopt the method of blasting hole by hole, resulting in poor smooth blasting effect in weak surrounding rock conditions and significant local over-excavation and under-excavation; (2) In large cities, the safety requirements for blasting construction environment are strict, and the source and use of detonating cord are limited, making it difficult to use segmented charging structure in actual construction. The amount of explosive in the surrounding holes is mainly small and concentrated at the bottom of the hole. Summary of the Invention

[0004] The purpose of this invention is to provide a method for efficient tunnel excavation blasting in soft surrounding rock in sensitive urban areas, which solves the problems of poor smooth blasting effect, significant local over- and under-excavation in soft surrounding rock conditions, and the limited source and use of detonating cord, which makes it difficult to use segmented charging structures in actual construction, and the problem that the amount of explosive in the peripheral holes is mainly small and concentrated at the bottom of the hole.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a method for efficient tunnel excavation and blasting in soft surrounding rock in sensitive urban areas, comprising the following steps:

[0006] S1: The combined wedge-shaped cut-out method is adopted to optimize the cut-out blasting method;

[0007] S2: The maximum number of simultaneous detonations of different types of blast holes in sensitive urban areas was obtained based on field test explosions.

[0008] S3: Calculate reasonable delay time intervals for different types of boreholes;

[0009] S4: Use a combination of a shaped charge tube and a charging device to charge the peripheral holes in sections.

[0010] Preferably, step S1 includes laying a row of large-diameter holes at the center of the slotted area, with a diameter d ranging from 7 to 10 cm, and arranged in the middle area of ​​the line connecting the slotted holes.

[0011] Preferably, the hole spacing h of the large-diameter holes is 2-5 times the hole diameter d.

[0012] Preferably, the angles of the slotted holes are θ, θ+Φ, θ+2Φ..., where θ ranges from 50° to 60° and Φ ranges from 5° to 12°.

[0013] Preferably, the range of the primary slotted hole H is 22-25 times the diameter of the empty hole.

[0014] Preferably, the method for determining the single-stage charge amount for the different types of boreholes is as follows:

[0015] First, a hole-by-hole detonation test needs to be conducted on-site, and vibration monitoring lines need to be laid out on the ground. By fitting the peak vibration velocity at different measuring points, the results can be obtained. The values ​​of K and a (where x is the horizontal distance from the measuring point to the working face and y is the vertical distance from the measuring point to the working face) are used to calculate the maximum single-stage charge of the cut hole. This formula is then used to determine the single-stage charge and detonation quantity for other different types of boreholes. Considering the free surface effect provided by the first detonated borehole and the effect of the borehole charge density coefficient, on-site vibration blasting tests are conducted to extract the particle vibration characteristics and rock-breaking effect to obtain the maximum single-stage charge of the cut hole. On-site monitoring tests are continued to adjust the maximum single-stage charge of auxiliary holes, bottom holes, and peripheral holes. The peak vibration velocity and blasting frequency of different types of boreholes are compared to determine the maximum single-shot charge (mQ) of subsequent auxiliary holes and bottom holes. 掏 And the amount of explosive charge nQ for each subsequent single detonation at the surrounding holes. 掏 .

[0016] Preferably, step S3 specifically includes applying the peak-shifting vibration reduction formula. The reasonable delay time intervals for the slotted holes, auxiliary holes, and bottom plate holes were calculated.

[0017] according to The delay time of the peripheral holes was calculated.

[0018] Preferably, the specific steps for determining T and Δt include first conducting on-site test blasting to obtain the natural dominant frequency f of seismic waves at multiple monitoring points on the ground, then calculating the average T value of the blasting seismic waves at the measuring points and determining the range of Δt values, setting up test groups within a reasonable Δt range, and continuing on-site blasting monitoring tests to obtain a delay time Δt that conforms to the characteristics of the surrounding rock at the site.

[0019] Preferably, step S4 includes adding a shaped charge tube along the axial direction of the borehole to form a shaped charge explosive, and on this basis, adding a shaped charge tube and vibration isolation material in the radial direction of the borehole to change the effective range of the radial blasting energy.

[0020] Preferably, the shaped charge device combining the shaped charge tube and the shaped charge cover includes a shaped charge tube and a shock-absorbing material in the transverse direction, a shaped charge cover in the radial direction, and a partition for fixing the shaped charge tube and the shaped charge cover.

[0021] As can be seen from the above technical solution, the present invention has the following beneficial effects:

[0022] This efficient tunnel boring and blasting method for weak surrounding rock in sensitive urban areas optimizes the cut-out blasting approach by employing a combined wedge-shaped cut-out configuration. Based on field test blasts, the maximum number of simultaneous detonations for different types of boreholes in sensitive urban areas was determined. Reasonable delay time intervals were calculated for different types of boreholes. A shaped charge tube combined with a charging device allows for segmented charging of peripheral holes. This method can be applied to drill-and-blast construction of subway tunnels in jointed surrounding rock conditions in urban areas. It effectively controls blasting vibration velocity while ensuring that the smooth blasting rock-breaking effect does not affect the construction progress, reducing construction costs and improving efficiency. The shaped charge tube structure integrates the features of currently available shaped charge tubes. It also flexibly replaces the application of detonating cord in underground engineering drill-and-blast construction, improving the safety of the blasting construction process. The equipment required for tunnel excavation blasting methods and peripheral hole charging structures is simple to manufacture, flexible, and highly applicable. It can be widely applied to the drill-and-blast construction of large-section subway tunnels in complex geological conditions in sensitive urban areas. It is effective and widely applicable, solving the problems of existing construction methods that often use hole-by-hole blasting, resulting in poor smooth blasting effects in weak surrounding rock conditions and significant local over- and under-excavation, as well as the limitations of detonating cord sources and uses, which make it difficult to use segmented charging structures in actual construction, and the problem that the amount of explosives in peripheral holes is mainly small and concentrated at the bottom of the hole. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the process of the present invention;

[0024] Figure 2 This is a schematic diagram of the slot hole arrangement of the present invention;

[0025] Figure 3 This is a schematic diagram of the spatial structure of the energy-concentrating tube cover of the present invention at a certain angle (axial direction of the borehole);

[0026] Figure 4 This is a schematic diagram of the spatial structure of the energy-concentrating tube cover from another angle (radial direction of the borehole);

[0027] Figure 5 This is a schematic diagram of the peripheral hole charging structure of the present invention;

[0028] Figure 6This is a plan view of the peripheral hole charging structure of the present invention;

[0029] Figure 7 This is a schematic diagram of the slotting blasting method of the present invention;

[0030] Figure 8 This is a schematic diagram of the blasting initiation sequence of the present invention.

[0031] In the diagram: 1. shaped charge cover; 2. shaped charge tube cover cutout; 3. shaped charge trough; 4. shaped charge tube cover device; 5. water sandbag; 6. shaped charge tube; 7. bottom shaped charge explosive; 8. perimeter hole wall; 9. industrial electronic detonator; 10. segmented charge; 11. void; 12. partition plate; 13. vibration isolation material. Detailed Implementation

[0032] 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.

[0033] like Figures 1-8 As shown, a method for efficient tunnel excavation and blasting in weak surrounding rock in sensitive urban areas includes the following steps:

[0034] S1: The combined wedge-shaped cut-out method is adopted to optimize the cut-out blasting method;

[0035] S2: The maximum number of simultaneous detonations of different types of blast holes in sensitive urban areas was obtained based on field test explosions.

[0036] S3: Calculate reasonable delay time intervals for different types of boreholes;

[0037] S4: Use a combination of a shaped charge tube and a charging device to charge the peripheral holes in sections.

[0038] Specifically, this includes optimizing the cut-out blasting method, adopting a combined wedge-shaped cut-out to improve the blasting effect and provide more free surface conditions for subsequent blast holes, auxiliary holes, and peripheral holes. Based on field test blasts (peak vibration velocity and blast block size distribution range at measuring points), the maximum number of simultaneous detonations for different types (e.g., cut-out holes, bottom plate holes, auxiliary holes, and peripheral holes) in urban sensitive areas is determined, enabling refined blasting design in urban sensitive areas. Reasonable delay time intervals are calculated for different types of blast holes, and the blasting network is carefully designed using industrial electronic detonators. For peripheral holes, the charge structure from the hole opening to the bottom consists of shaped charge, industrial electronic detonator, air gap section, segmented charge, and corresponding water-sandbags. An efficient shaped charge tube combined with a charging device is proposed to achieve segmented charging of peripheral holes. This technology improves the distribution of explosives in the surrounding holes by using a shaped charge tube combined with a charging device to charge the surrounding holes in segments. It can be applied to the drilling and blasting method for subway tunnels in urban areas with well-developed jointed rock conditions. While effectively controlling the blasting vibration velocity, it ensures that the smooth blasting rock-breaking effect does not affect the construction progress, reducing construction costs and improving efficiency. The shaped charge tube structure not only integrates the characteristics of shaped charge tubes currently on the market, but also flexibly replaces detonating cords in underground engineering drilling and blasting construction, improving the safety of the blasting process. The equipment required for the tunnel excavation blasting method and the surrounding hole charging structure is simple to manufacture, flexible, and highly applicable. It can be widely applied to the drilling and blasting construction of large-section subway tunnels in complex geological conditions in sensitive urban areas, demonstrating effectiveness and broad applicability.

[0039] Specifically, step S1 includes a method for arranging large-diameter holes. This involves laying a row of large-diameter holes 11 at the center of the cut area. The diameter d of these holes ranges from 7 to 10 cm, and they are arranged in the middle area of ​​the line connecting the cut holes. The spacing between the holes is (2-5)d. The angles of the cut holes are successively θ, θ+Φ, θ+2Φ… (50°<θ<60°, 5°<Φ<12°). The spacing between the first-order cut holes is H=(22-25)d. The number of rows of cut holes and the total number of blast holes are determined by the tunnel cross-section size and the cyclic advance, while ensuring that the area of ​​the cut hole region is not less than 1 / 4 of the overall excavation cross-section area. The method for determining the single-section charge of different types of blast holes is as follows:

[0040] First, a hole-by-hole detonation test needs to be conducted on-site, and vibration monitoring lines need to be laid out on the ground. By fitting the peak vibration velocity at different measuring points, the results can be obtained. The values ​​of K and a (where x is the horizontal distance from the measuring point to the working face and y is the vertical distance from the measuring point to the working face) are used to calculate the maximum single-stage charge of the cut hole. This formula is then used to determine the single-stage charge and detonation quantity for other different types of boreholes. Considering the free surface effect provided by the first detonated borehole and the effect of the borehole charge density coefficient, on-site blasting vibration tests are conducted to extract the particle vibration characteristics (peak velocity and dominant frequency) and rock-breaking effect (blasting block size) to obtain the maximum single-stage charge of the cut hole. On-site monitoring tests are then conducted to adjust the maximum single-stage charge of auxiliary holes, bottom holes, and peripheral holes. The peak velocity and blasting dominant frequency values ​​of different types of boreholes are compared to determine the maximum single-shot charge mQ of subsequent auxiliary holes and bottom holes. 掏 And the amount of explosive charge nQ for each subsequent single detonation at the surrounding holes. 掏 .

[0041] The design utilizes industrial electronic detonators 9, with reasonable delay intervals for the slotted holes, auxiliary holes, and base plate holes based on the staggered vibration reduction formula. Calculations show that the delay time for the peripheral holes is... The calculation shows that the specific determination process is as follows: First, a field test blast is conducted to obtain the natural dominant frequency f of seismic waves at multiple monitoring points on the ground surface. Then, the average T value of the blasting seismic waves at the measuring points is calculated, and the range of Δt is determined. Test groups are set up within a reasonable Δt range, and field blasting monitoring tests are continued (through vibration velocity and field blasting block size) to obtain a delay time Δt that conforms to the characteristics of the surrounding rock. The integrated shaped charge tube device adds a shaped charge tube 6 along the axial direction of the blast hole to form a shaped charge explosive, which is used to detonate adjacent interval explosives. Based on this, the radial blasting energy is changed by adding a shaped charge tube 6 and seismic isolation material 13 in the radial direction of the blast hole. The main structure of the integrated shaped charge tube and cover includes a shaped charge tube and vibration isolation material in the horizontal direction, a shaped charge cover in the radial direction, and a partition plate for fixing the shaped charge tube and cover. The shaped charge groove 3 in the shaped charge tube 6 uses aluminum, copper and PVC materials. Meanwhile, the vibration isolation material in the radial direction includes, but is not limited to, foam, asphalt and polyethylene closed-cell foam. The vibration isolation material 13 includes, but is not limited to, PVC plastic materials. The distance between the shaped charge 7 at the bottom of the hole and the subsequent charge 10 is within 40cm. In the use of the integrated shaped charge tube and cover device, the vibration isolation material 13 is placed on the side facing the surrounding rock, and the shaped charge tube cover cut 2 is facing the blasting excavation area.

[0042] An embodiment of a specific implementation process is also provided:

[0043] A test was conducted at the site of a subway station's upper steps to verify the design. The original plan involved sequential blasting. The main body of the station is located in slightly weathered granite, with the subway arch buried at a depth of 30.6-35.7m and the slightly weathered rock layer thickness at 10-24m. The surrounding rock was classified as IV1 and IV2. To reduce the impact of blasting vibration on sensitive urban areas, the single-cycle advance was specified as 0.75m during construction. Two main difficulties arose during the initial blasting operation: firstly, the blasting advance was limited, resulting in a long construction period; secondly, the excavation area had well-developed joints, making sequential blasting ineffective and leading to significant over- and under-excavation. The method proposed in this patent is now used to optimize the on-site blasting design. The specific implementation process is as follows:

[0044] First, on-site blasting vibration monitoring tests and numerous on-site blasting tests were conducted. Based on the on-site test results, the maximum single-shot charge value for the cut hole was determined to be 1.2 kg, meaning the charge per cut hole was 0.6 kg. The charge values ​​for auxiliary holes and bottom plate holes were (1-1.5)Q. 掏 If the maximum single-shot charge is 0.9 kg, then the maximum number of detonating holes is 2-3; the charge for the peripheral holes is (1.5-2)Q. 掏 That is, the amount of large single-explosive charge is 0.9-1.2kg, which corresponds to a maximum number of detonation holes of 8. Following this idea, the detonation method is optimized to detonate the slotting holes in pairs, detonate the auxiliary holes and bottom plate holes 2-3 times together, detonate the holes around the arch together 8 times, and detonate the holes around the central partition wall 3 times together in order to control the degree of blasting damage at the central partition wall, thereby realizing the refined design of the blasting design;

[0045] Then, using industrial electronic detonators, a carefully designed system was implemented, with reasonable delay intervals for the slotted holes, auxiliary holes, and base plate holes determined by the staggered vibration reduction formula. The delay time for the surrounding holes is determined by Calculations show that, firstly, field test blasting was conducted, and the average period f value of seismic waves at multiple monitoring points on the ground was obtained as 45Hz. Then, the average T value of the blasting seismic waves was obtained as 22ms, and the range of Δt values ​​was determined. Finally, field blasting monitoring tests were conducted (through vibration velocity and field blasting block size) to obtain the delay time of the slotted holes, auxiliary holes, and bottom plate holes, which are consistent with the characteristics of the surrounding rock, as 35ms, and the delay time between the peripheral hole segments as 5ms. Industrial electronic detonators were used to initiate the blasting initiation network.

[0046] Based on the results of field tests, the different cut hole depths were determined to be 1.15m, 1.05m and 1m respectively, the different cut hole angles were 54°, 63° and 75° respectively, the spacing between the first-level cut holes was H of 1.6m, and a 9cm diameter hole was laid at the center of the line connecting the cut holes, while ensuring that the cut area was not less than 1 / 4 of the total excavation cross-sectional area.

[0047] The on-site parameters are shown in Table 1. The charge per hole in the perimeter holes is one roll, which is cut into two parts, 1 / 3 and 2 / 3 of the length of the charge, 10. The 2 / 3 length of the charge is inserted into the shaped charge tube cover 4, with the shaped charge cover 1 facing the hole opening. The remaining 1 / 3 of the charge is then inserted into the shaped charge tube 6, and the remaining charge is loaded into the predetermined position using the pre-marked blast holes, keeping the two charge segments about 40cm apart and aligning one side of the vibration isolation material 13 with the surrounding rock. Finally, the blasting is carried out normally according to the optimized scheme. It is found that the blasting vibration intensity at any point on the ground is far below the safe vibration velocity threshold of 0.5cm / s, and the smooth blasting formation of the perimeter holes is good. This indicates that when using this blasting scheme, it can effectively control the blasting vibration velocity and improve the overall blasting rock breaking quality and the smooth blasting formation effect of the perimeter holes.

[0048]

[0049] Table 1 Optimized field blasting parameters

[0050] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for efficient tunnel excavation and blasting in weak surrounding rock in sensitive urban areas, characterized in that, The specific steps include: S1: The combined wedge-shaped cut-out method is adopted to optimize the cut-out blasting method; S2: The maximum number of simultaneous detonations of different types of blast holes in sensitive urban areas, obtained from field test explosions; The method for determining the single-stage charge amount for different types of boreholes is as follows: First, a hole-by-hole detonation test needs to be conducted on-site, and vibration monitoring lines need to be laid out on the ground. By fitting the peak vibration velocity at different measuring points, the results can be obtained. middle K , a Value; where: x is the horizontal distance from the measuring point to the working face, y is the vertical distance from the measuring point to the working face. Then, the maximum single-stage charge of the cut hole is calculated according to the formula, and then the single-stage charge and number of detonations for other different types of blast holes are determined. Considering the free surface effect provided by the first blast hole and the effect of the hole charge density coefficient, on-site blasting vibration test blasting is carried out to extract the particle vibration characteristics and rock breaking effect to obtain the maximum single-stage charge of the cut hole. On-site monitoring test is carried out to adjust the maximum single-stage charge of auxiliary holes, bottom plate holes and peripheral holes. The peak vibration velocity and blasting main frequency value of different types of blast holes are compared to determine the maximum single-shot charge mQ of subsequent auxiliary holes and bottom plate holes. 掏 And the amount of explosive charge nQ for each subsequent single detonation at the surrounding holes. 掏 Where m and n are coefficients; S3: Calculate reasonable delay time intervals for different types of boreholes. Specific steps include applying the peak-shifting vibration reduction formula. The reasonable delay time intervals for the slotting holes, auxiliary holes, and bottom plate holes are calculated, where T is the period of the blasting seismic wave and n is an integer; according to The delay time of the peripheral holes was calculated; The T and The specific steps include first conducting on-site test explosions to obtain the natural dominant frequencies of seismic waves from multiple monitoring points on the surface. f Then, the average T value of the seismic wave from the blasting at the measuring point is calculated and determined. The range of values ​​for is within a reasonable range. Test groups were set up within the area, and on-site blasting monitoring tests were continued to obtain delay times consistent with the characteristics of the surrounding rock. ; S4: Use a combination of a shaped charge tube and a charging device to charge the peripheral holes in sections.

2. The method for efficient tunnel excavation and blasting in weak surrounding rock in urban sensitive areas according to claim 1, characterized in that: Step S1 includes laying a row of large-diameter holes at the center of the slotted area, with a diameter d ranging from 7 to 10 cm, and arranged in the middle area of ​​the line connecting the slotted holes.

3. The method for efficient tunnel excavation and blasting in weak surrounding rock in urban sensitive areas according to claim 2, characterized in that, The spacing h between the large-diameter holes is 2-5 times the diameter d of the hole.

4. The efficient tunneling and blasting method for weak surrounding rock in urban sensitive areas according to claim 1, characterized in that: The angles of the slotted holes are as follows: , + Φ , +2 Φ ..., the aforementioned The range is 50 o < <60 o The Φ The range is 5 o < Φ <12 o .

5. The efficient tunneling and blasting method for weak surrounding rock in urban sensitive areas according to claim 1, characterized in that: The range of the primary slot hole H is 22-25 times the diameter of the empty hole, where H represents the spacing between the primary slot holes.

6. The method for efficient tunnel excavation and blasting in weak surrounding rock in urban sensitive areas according to claim 1, characterized in that: Step S4 includes adding a shaped charge tube along the axial direction of the borehole to form a shaped charge explosive, and then adding a shaped charge tube and vibration isolation material in the radial direction of the borehole to change the effective range of the radial blasting energy.

7. The method for efficient tunnel excavation and blasting in weak surrounding rock in urban sensitive areas according to claim 1, characterized in that: The charge device combining the shaped charge tube and the shaped charge cover includes a shaped charge tube and a shock-absorbing material in the transverse direction, a shaped charge cover in the radial direction, and a partition for fixing the shaped charge tube and the shaped charge cover.

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