A method for coordinated control of vibration amplitude and frequency in blasting during tunnel excavation with small clearance

Abstract

This invention discloses a method for coordinated control of blasting vibration amplitude and frequency in tunnel excavation with small clearance, comprising the following steps: (1) eccentrically arranging slotting holes on the tunnel face and arranging auxiliary holes in a ring from the slotting area toward the tunnel design outline, with the spacing between auxiliary holes gradually decreasing; (2) adjusting the slotting holes to detonate from the bottom to the top, appropriately increasing the inter-hole delay on the side away from the interbedded rock and appropriately decreasing the inter-hole delay on the side closer to the interbedded rock; (3) specifically conducting blasting vibration monitoring in typical areas of the near and middle-far blasting zones, such as the interbedded rock sidewalls and arches, and simultaneously feeding back the monitoring results of blasting vibration amplitude and frequency; (4) simultaneously determining whether the blasting vibration amplitude and frequency meet the safety control requirements; (5) optimizing and adjusting the position of the blasting holes and the detonation network on the tunnel face according to steps (1) and (2) until the blasting vibration amplitude and frequency meet the safety requirements. The method of this invention reduces the high-frequency vibration amplitude of the surrounding rock near the tunnel face and adjusts the amplitude and frequency of the far-field tunnel face, avoiding low-amplitude resonance amplification. This effectively controls blasting vibration in tunnels with small clearances, especially in interbedded rock. The method of this invention is practical, feasible, and simple to operate.

Description

Technical Field

[0001] This invention relates to the fields of engineering blasting and tunnel engineering technology, specifically to a method for coordinated control of vibration amplitude and frequency in tunnel blasting with small clearance. Background Technology

[0002] Small-clearance tunnels, characterized by fewer restrictions from terrain and route, simpler construction processes, and controllable construction costs, have experienced rapid development and widespread application in tunnel construction. However, due to the small clearance between the left and right tunnels, the blasting vibrations during drilling and blasting can adversely affect the interbedded rock within the tunnel and the supporting lining of the preceding tunnel, threatening tunnel safety and stability and hindering tunnel excavation efficiency. As small-clearance tunnels are increasingly adopted in tunnel construction, the clearance between the left and right tunnels is becoming smaller, and the thickness of the interbedded rock within the tunnel is also decreasing. This makes the adverse effects of blasting vibrations during subsequent tunnel excavation on the interbedded rock and the supporting lining of the preceding tunnel even more pronounced.

[0003] Excessive blasting vibration amplitude directly affects the safety and stability of tunnel structures. Even when the blasting vibration amplitude is below the permissible safe vibration velocity, blasting vibration still poses a potential threat to the safety and stability of tunnel structures. This is mainly manifested in localized damage to the tunnel structure caused by high-frequency vibration in the near-field zone of the blast, and amplification of tunnel structure vibration induced by low-frequency vibration in the mid-to-far field zone. These adverse effects are particularly pronounced in tunnels with thin interbedded rock structures and small clearances. Therefore, controlling blasting vibration in tunnels with small clearances requires addressing both the amplitude and frequency of blasting vibration. However, current tunnel blasting vibration control mainly focuses on amplitude control, with relatively little and insufficiently systematic content on frequency regulation. The impact of blasting vibration on tunnels with small clearances is more prominent, necessitating the development of blasting vibration control technologies for small clearance tunnels that integrate amplitude and frequency regulation. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing vibration control technologies for blasting in tunnel excavation with small clearance by providing a method for controlling vibration in tunnel excavation with small clearance by synergistically regulating amplitude and frequency.

[0005] The technical solution adopted in this invention is as follows: A method for coordinated control of vibration amplitude and frequency in blasting during small-clearance tunnel excavation, characterized by the following steps:

[0006] (1) Adjust the position of the blast holes at the tunnel face, specifically: ① Arrange the slotting holes eccentrically at the tunnel face, with the slotting area located on the side of the tunnel centerline away from the interbedded rock; ② Arrange auxiliary holes in circles from the slotting area toward the tunnel design outline, with the spacing between auxiliary holes gradually decreasing from the slotting area toward the interbedded rock; ③ Arrange the blasting holes according to the conventional design.

[0007] The eccentricity of the cut area should be such that, while meeting the drilling space requirements of the rock drilling machinery, it is as far away as possible from the intermediate rock. The variation in the spacing of the auxiliary holes should accommodate the thickness of the blasting layer (the distance between the last ring of auxiliary holes and the blasting holes). d Spacing between light burst holes s .

[0008] (2) Adjust the tunnel blasting initiation network, specifically: ① Slot holes are blasted sequentially, with the slot holes on the side furthest from the interbedded rock being blasted first, and the inter-hole delay being appropriately increased compared to conventional slot holes; slot holes on the side closer to the interbedded rock are blasted later, with the inter-hole delay being appropriately decreased compared to conventional slot holes; the overall blasting sequence of the slot holes is from bottom to top; ② Auxiliary holes are blasted sequentially or in groups, with the blast holes in groups not exceeding the range of the same circle of blast holes, and the inter-hole delay of the auxiliary holes on the side furthest from the interbedded rock being relatively... The inter-hole delay of conventional auxiliary holes is appropriately increased, while the inter-hole delay of auxiliary holes closer to the interbedded rock is appropriately decreased compared to conventional auxiliary holes. The inter-row delay of auxiliary holes is also appropriately decreased compared to conventional delays. The overall detonation sequence of auxiliary holes is from bottom to top. ③ The group of smooth blasting holes is detonated, and the total amount of explosives in the group of holes detonated at the same time does not exceed the maximum single-stage explosives for slotting blasting. The smooth blasting holes are detonated segment by segment from the side away from the interbedded rock to the side closer to the interbedded rock. The inter-segment delay of smooth blasting holes is appropriately increased compared to conventional smooth blasting holes.

[0009] The appropriate increase in delay refers to the increased delay Δ T’ Less than the normal delay Δ T 2 times, that is, Δ T <Δ T’ <2Δ T The aforementioned appropriate reduction in delay refers to the reduced delay Δ T’’ Greater than the normal delay Δ T 0.5 times, or 0.5Δ T <Δ T’’ <Δ T .

[0010] (3) Feedback on blasting vibration monitoring, specifically: ① Monitoring points are set up on the sidewalls of the interbedded rock and the rock mass at the top of the arch in the near-blasting zone, and on the lining structure of the sidewalls of the interbedded rock and the top of the arch in the middle and far-blasting zone to carry out blasting vibration monitoring; ② The monitoring results of the blasting vibration amplitude and main frequency of the sidewalls of the interbedded rock and the top of the arch in the near-blasting zone and the middle and far-blasting zone are read.

[0011] The blasting proximity zone refers to the distance from the blast center (distance to the center of the blast source). D Less than the minimum thickness of the adjacent intermediate rock d min The area, namely D < d min The area referred to as the "far-center zone" in blasting refers to the area at which the blast center is located. DGreater than the distance Δ between the working face and the nearest secondary lining x The area, namely D >Δ x The area.

[0012] (4) Determine whether the blasting vibration amplitude and frequency meet the safety requirements, specifically: ① Determine whether the blasting vibration amplitude and frequency of the middle rock sidewall and the rock mass at the top of the arch in the blasting near zone meet the high-frequency damage control requirements; ② Determine whether the blasting vibration amplitude and frequency of the middle rock sidewall and the lining structure at the top of the arch in the blasting far zone meet the resonance control requirements.

[0013] The high-frequency damage control requirement refers to the near-field high-frequency blasting vibration amplitude meeting the corresponding blasting vibration control standards. The resonance control requirement refers to the distribution of the dominant frequency of blasting vibration in the mid-to-far zone. f ~ N ( m , s The natural frequency of the lining structure f 0 satisfies n f 0< m -3 s , or n f 0> m +3 s , ( n= 1, 2, 3,…), where: f The dominant frequency of blasting vibration, N ( m , s The mean is m Standard deviation is s The normal distribution f 0 represents the natural frequency of the lining structure.

[0014] (5) Optimize and adjust the position of the blast holes and the detonation network according to steps (1) and (2) until the blasting vibration amplitude and frequency meet the safety requirements. Specifically: ① If the blasting vibration amplitude of the near-field slotting exceeds the blasting vibration control standard, then further arrange slotting holes in the direction away from the interbedded rock; ② If the blasting vibration amplitude of the near-field auxiliary hole blasting and smooth blasting exceeds the blasting vibration control standard, then reduce the number of blast holes that are detonated together for auxiliary hole group blasting and smooth blasting; ③ If the blasting vibration frequency in the far-field blasting does not meet the resonance control requirements, then appropriately reduce the inter-hole delay of the corresponding blast holes.

[0015] The beneficial effects of this invention are as follows:

[0016] (1) The slotting holes are arranged eccentrically away from the interbedded rock, which increases the distance between the slotting area and the thin interbedded rock, and can significantly reduce the impact of slotting blasting vibration on the interbedded rock; the spacing of the auxiliary holes gradually decreases from the slotting area to the interbedded rock, which reduces the minimum resistance line of the auxiliary holes adjacent to the thin interbedded rock, and can effectively reduce the blasting vibration of the auxiliary holes.

[0017] (2) More importantly, the eccentric arrangement, combined with the adjustment of the borehole detonation sequence and delay, plays a good role in synergistically controlling the amplitude and frequency. Specifically, the boreholes on the side away from the interbedded rock are detonated first, forming a free surface for the boreholes on the side closer to the interbedded rock, which can reduce the blasting vibration of the boreholes on the side closer to the interbedded rock; the inter-hole delay of the boreholes on the side away from the interbedded rock is appropriately increased, and the inter-hole delay of the boreholes on the side closer to the interbedded rock is appropriately decreased, so that the blasting vibration spectrum in the near-field zone shifts to the low-frequency part and the blasting vibration spectrum in the mid-to-far-field zone shifts to the high-frequency part, which can effectively suppress the adverse phenomena such as local damage caused by high-frequency vibration in the near-field zone and structural resonance induced by low-frequency vibration in the mid-to-far-field zone. Generally, the main frequency of the slotting blasting vibration is < the main frequency of the auxiliary hole blasting vibration is < the main frequency of the smooth blasting vibration, and the amplitude of the slotting blasting vibration is < the amplitude of the auxiliary hole blasting vibration is < the amplitude of the smooth blasting vibration. The inter-row delay of auxiliary holes is appropriately reduced compared to the conventional delay, causing the blasting vibration spectrum in the mid-to-far zone to shift towards the high-frequency portion, effectively suppressing the adverse phenomenon of structural resonance induced by low-frequency vibration in the mid-to-far zone. The inter-segment delay of smooth blasting holes is appropriately increased compared to the conventional inter-segment delay of smooth blasting holes, causing the blasting vibration spectrum in the near zone to shift towards the low-frequency portion, effectively suppressing the adverse phenomenon of local damage caused by high-frequency vibration in the near zone.

[0018] (3) In typical areas of the near and middle-far blasting zones, blasting vibration monitoring was carried out in sensitive areas such as the sidewalls and arches of the interbedded rock. The monitoring areas and locations were clearly defined, and the blasting vibration monitoring was specific and feasible.

[0019] (4) The control requirements for the main frequency of blasting vibration were proposed, which clarified the direction for the control of blasting vibration frequency; at the same time, it was determined whether the amplitude and frequency of blasting vibration met the safety control requirements, which provided a basis for the coordinated control of the amplitude and frequency of blasting vibration. Attached Figure Description

[0020] Figure 1 This is a schematic diagram illustrating the implementation process of a method for coordinated control of vibration amplitude and frequency in tunnel excavation with small clearance, according to the present invention.

[0021] Figure 2 This is a schematic diagram of conventional blasting design for tunneling with small clearance.

[0022] Figure 3 This is a schematic diagram of the blasting design for small-clearance tunnel excavation after adjustment using the method of the present invention. Detailed Implementation

[0023] The present invention will now be described in detail with reference to the embodiments shown in the accompanying drawings. However, it should be noted that these embodiments are not intended to limit the present invention. Any equivalent changes or substitutions in function, method, or structure made by those skilled in the art based on these embodiments are within the scope of protection of the present invention.

[0024] This example illustrates a tunnel with a small clearance of 6 meters, and the distance between the tunnel face and the nearest secondary lining is 70 meters. A schematic diagram of a conventional tunneling blasting design is shown below. Figure 2 As shown, when conventional blasting design is adopted, the amplitude of blasting vibration monitored in the near zone of the tunnel exceeds the safety allowable standard of 15 cm / s, and the dominant frequency of blasting vibration monitored in the middle and far zone of the tunnel is close to the dominant frequency of the tunnel lining structure of 10 Hz. Therefore, the method proposed in this invention is used to coordinately control the amplitude and frequency of blasting vibration in this small-clearance tunnel.

[0025] The flowchart illustrating the method for coordinated control of blasting vibration amplitude and frequency in small-clearance tunnel excavation described in this invention is as follows: Figure 1 As shown, it includes the following steps:

[0026] (1) Adjust the position of the blast holes at the tunnel face.

[0027] The placement of the cut holes was adjusted. While ensuring sufficient extension space for the rock drilling machinery, the original cut holes were shifted away from the interbedded rock (to the left) until they were all located to the left of the tunnel centerline. The placement of the auxiliary holes was also adjusted. Auxiliary holes were arranged in concentric circles from the adjusted cut area towards the tunnel design outline, with the spacing between rows changed from 80cm to 90cm, 80cm, and 70cm respectively from the cut area towards the tunnel design outline. The placement of the smooth blasting holes remained unchanged.

[0028] (2) Adjust the blasting initiation network for tunnel excavation.

[0029] The symmetrical detonation of the cut holes in rows (vertical rows) has been adjusted to sequential detonation. Cut holes furthest from the interbedded rock (left side) are detonated first, with a delay slightly increased from the original 50ms inter-segment delay. The inter-hole delay is adjusted to 55ms, and the inter-row delay is set to 60ms. Cut holes closest to the interbedded rock (right side) are detonated later, with a delay slightly decreased from the original 50ms inter-segment delay. The inter-hole delay is adjusted to 42ms, and the inter-row delay is set to 47ms. The overall detonation sequence of the cut holes is adjusted to detonate from bottom to top.

[0030] The auxiliary holes were changed from being detonated ring by ring to being detonated segment by segment, with 2-3 holes detonated at a time. Auxiliary holes furthest from the interbedded rock were detonated first, followed by those closer to the interbedded rock. For the first three rings, auxiliary holes were detonated segment by segment, with 3 holes detonated per row. For these auxiliary holes closer to the interbedded rock, the inter-row delay was set to 50ms, and the inter-segment delay within the ring was appropriately reduced to 27ms. For the ring of auxiliary holes immediately adjacent to the smooth blasting holes, auxiliary holes were detonated segment by segment, with 2 holes detonated per segment. For the side furthest from the interbedded rock (left side of the tunnel centerline), the delay was appropriately increased, and the inter-segment delay was adjusted to 55ms. For the side closer to the interbedded rock (right side of the tunnel centerline), the delay was appropriately reduced, and the inter-segment delay was adjusted to 27ms.

[0031] The simultaneous detonation of the right circumference of the smooth blasting holes was adjusted to a segmented detonation of 5 holes per section. The total charge of the 5 smooth blasting holes did not exceed the maximum charge of a single section for slotting blasting. The smooth blasting holes were detonated segment by segment from the side furthest from the interbedded rock to the side closer to the interbedded rock. The delay on the side furthest from the interbedded rock (left side of the tunnel centerline) was appropriately increased, and the inter-segment delay was adjusted to 55ms. The delay on the side closer to the interbedded rock (right side of the tunnel centerline) was appropriately decreased, and the inter-segment delay was adjusted to 27ms.

[0032] (3) Monitoring and feedback of tunneling and blasting vibration.

[0033] Monitoring points were set up on the rock walls and arch-top rock mass in the near-blast zone (within 5 m of the blast center distance) and on the rock walls and arch-top lining structure in the mid-to-far-blast zone (within 70 m of the blast center distance) to monitor blasting vibration. The monitoring results of blasting vibration amplitude and dominant frequency in the near-blast zone and mid-to-far-blast zone were read. The maximum blasting vibration amplitude in the near-blast zone was 11.6 cm / s, while the dominant frequency in the mid-to-far-blast zone was 37.3 Hz, with a standard deviation of 0.2 Hz.

[0034] (4) Determine whether the vibration amplitude and frequency of tunneling blasting meet the safety requirements.

[0035] The blasting vibration amplitude of the middle and interbedded rock sidewalls and the rock mass at the top of the arch in the near-field blasting zone is less than 15 cm / s, and the dominant blasting vibration frequency of the middle and interbedded rock sidewalls and the lining structure at the top of the arch in the middle and far-field blasting zone is less than 15 cm / s. f With the natural frequency of the lining structure f 0 satisfies n f 0< f μ -3 f σ , or n f 0> f μ +3 f σ relation.

[0036] (5) The vibration amplitude and frequency of the tunneling blasting meet the safety requirements, and the subsequent construction shall be carried out in accordance with the adjusted blasting design.

[0037] The above description is merely one embodiment of this patent and is not intended to limit the patent in any other way. Any person skilled in the art may make changes or modifications to the disclosed technical content to create equivalent embodiments. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of this patent, without departing from the scope of the patent's technical solution, shall still fall within the protection scope of this patent's technical solution.

Claims

1. A method for coordinated control of vibration amplitude and frequency in blasting during tunnel excavation with small clearance, characterized in that, Includes the following steps: (1) Adjust the position of the blast holes at the tunnel face eccentrically; (2) Adjust the blasting initiation network of the tunnel; (3) Monitor and provide feedback on blasting vibration; (4) Determine whether the amplitude and frequency of blasting vibration meet the safety requirements; (5) Optimize and adjust the position of the blast holes and the initiation network at the tunnel face according to steps (1) and (2) until the amplitude and frequency of blasting vibration meet the safety requirements. The step (1) eccentrically adjusts the position of the blast holes at the tunnel face, including eccentrically arranging slotting holes at the tunnel face and arranging auxiliary holes in circles from the slotting area toward the tunnel design outline. The method involves eccentrically arranging slotting holes at the tunnel face, with the slotting area located on the side of the tunnel centerline away from the interbedded rock, while ensuring sufficient extension space for drilling machinery, and keeping as far away from the interbedded rock as possible. The auxiliary holes are arranged in concentric circles from the slotted area toward the tunnel design outline. The spacing between the auxiliary holes gradually decreases from the slotted area toward the middle interbedded rock. This should meet the requirement of the thickness of the blasting layer, that is, the distance δ between the last ring of auxiliary holes and the blasting holes is greater than the spacing s of the blasting holes. The step (2) is to adjust the tunnel blasting initiation network, including adjusting the individual initiation of the slotting holes, the individual or group initiation of the auxiliary holes, and the group initiation of the blasting holes. Adjust the detonation sequence of the slotted holes. The slotted holes on the side furthest from the interbedded rock are detonated first, with the inter-hole delay appropriately increased compared to the conventional slotted holes. The slotted holes on the side closer to the interbedded rock are detonated later, with the inter-hole delay appropriately decreased compared to the conventional slotted holes. The overall detonation sequence of the slotted holes is from bottom to top. Adjust the auxiliary holes to be detonated one hole at a time or in groups. The number of holes detonated in groups should not exceed the range of the same circle of holes. The inter-hole delay of auxiliary holes on the side away from the interbedded rock should be appropriately increased compared with the inter-hole delay of conventional auxiliary holes. The inter-hole delay of auxiliary holes on the side closer to the interbedded rock should be appropriately decreased compared with the inter-hole delay of conventional auxiliary holes. The inter-row delay of auxiliary holes should be appropriately decreased compared with the conventional delay. The overall detonation sequence of auxiliary holes is from bottom to top. Adjust the initiation of the smooth blasting hole group, while the total charge of the initiation group does not exceed the maximum charge of a single segment in slotting blasting. The smooth blasting holes are initiated segment by segment from the side away from the interbedded rock to the side closer to the interbedded rock. The inter-segment delay of the smooth blasting holes is appropriately increased compared with the inter-segment delay of conventional smooth blasting holes. The appropriate increase in delay means that the increased delay ΔT' is less than twice the normal delay ΔT, i.e., ΔT < ΔT' < 2ΔT; the appropriate decrease in delay means that the decreased delay ΔT'' is greater than 0.5 times the normal delay ΔT, i.e., 0.5ΔT < ΔT'' < ΔT. Step (5) optimizes and adjusts the position of the blast holes and the detonation network of the face according to steps (1) and (2) until the blasting vibration amplitude and frequency meet the safety requirements. Specifically, if the blasting vibration amplitude of the near-field slotting exceeds the blasting vibration control standard, slotting holes are arranged further away from the interbedded rock. If the blasting vibration amplitude of the near-field auxiliary hole blasting and smooth blasting exceeds the blasting vibration control standard, the number of blast holes detonated together for auxiliary hole group blasting and smooth blasting is reduced. If the blasting vibration frequency in the middle and far-field blasting does not meet the resonance control requirements, the inter-hole delay of the corresponding blast holes is appropriately reduced.

2. The method for coordinated control of vibration amplitude and frequency in tunnel boring with small clearance as described in claim 1, characterized in that, The step (3) blasting vibration monitoring feedback specifically involves: setting up monitoring points on the middle rock sidewall and the rock mass at the top of the arch in the near blasting zone, and on the middle rock sidewall and the lining structure at the top of the arch in the middle and far blasting zone to carry out blasting vibration monitoring; and reading the monitoring results of the blasting vibration amplitude and main frequency at the middle rock sidewall and the top of the arch in the near and middle and far blasting zones. The near-blasting zone refers to the area where the distance from the blast center D is less than the minimum thickness δmin of the adjacent interbedded rock, i.e., the area where D < δmin; the far-blasting zone refers to the area where the distance from the blast center D is greater than the distance Δx between the working face and the nearest secondary lining, i.e., the area where D > Δx; the blast center distance refers to the distance to the center of the blast source.

3. The method for coordinated control of vibration amplitude and frequency in tunnel boring with small clearance as described in claim 1, characterized in that, Step (4) determines whether the blasting vibration amplitude and frequency meet the safety requirements, specifically: determining whether the blasting vibration amplitude and frequency of the middle-walled rock and the rock mass at the top of the arch in the near-blasting zone meet the high-frequency damage control requirements; determining whether the blasting vibration amplitude and frequency of the middle-walled rock and the lining structure at the top of the arch in the far-blasting zone meet the resonance control requirements; The high-frequency damage control requirement refers to the near-field high-frequency blasting vibration amplitude meeting the corresponding blasting vibration control standard; the resonance control requirement refers to the distribution of the dominant frequency of blasting vibration in the mid-to-far field. f ~ N ( μ , σ The natural frequency of the lining structure f 0 satisfies n f 0< μ- 3 σ , or n f 0> μ +3 σ , n= 1, 2, 3, ..., where: f The dominant frequency of blasting vibration, N ( μ , σ The mean is μ Standard deviation is σ The normal distribution f 0 represents the natural frequency of the lining structure.

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