Low-disturbance blasting vibration control construction method for tunnel with pilot hole in fracture zone section

Abstract

The invention discloses a pilot hole-containing low-disturbance blasting vibration control construction method for a tunnel in a fracture zone section, which comprises the following steps of: S1, dividing a tunnel face into a blasting area and a non-blasting area from inside to outside, excavating the non-blasting area, and drilling a vault pipe shed and an outline advanced small guide pipe at the same time; s2, excavation construction is carried out on the blasting area, and drilling construction of a vault pipe shed and a contour advanced small guide pipe is synchronously carried out; s3, after the arch crown pipe shed and the outline advanced small guide pipe of the to-be-blasted area are drilled, the pipe shed and the advanced small guide pipe are jacked into the hole without grouting, and a vibration reduction hole group belt is formed; and S4, blasting excavation is conducted on the blasting area in sequence, and grouting reinforcement is conducted on the vault pipe shed and the outline advanced small guide pipes in stages in the blasting excavation process. According to the method, blasting excavation can be adopted in tunnel surrounding rock poor and fracture fracture zones, surrounding rock disturbance is small, and the construction safety performance is guaranteed.

Description

Technical Field

[0001] The present invention relates to the field of tunnel blasting construction methods, and more particularly to a low-disturbance blasting and vibration-controlled construction method for a broken zone tunnel including a pilot hole. Background Art

[0002] In the field of long and large tunnel projects, it is inevitable to encounter fault and fracture zone strata, which urges continuous innovation in fault and fracture zone strata treatment technology. At present, in the construction of fracture zone tunnels, the commonly used construction method is blasting excavation, and the common construction methods are step method, full section, single (double) side wall pit method, etc.

[0003] Conventional tunnel blasting construction is usually suitable for IV a The strata with grade 5 or above surrounding rock and good integrity. Since blasting operations cause great disturbance to the surrounding rock, tunnel excavation construction in soft strata such as fractured zones is risky and weak blasting technology needs to be adopted. Traditional methods usually take some measures, such as a large amount of advance support for the tunnel face in advance, including advance pipe roofs, small guide tubes, curtain grouting, etc., and blasting construction still uses traditional excavation methods, but still faces challenges such as uncontrollable blasting vibration propagation and insufficient support efficiency. Uncontrolled blasting vibration may cause destructive effects on existing tunnels and soft surrounding rock, especially in tunnels with soft and broken surrounding rock sections, which are prone to landslides. In order to reduce blasting vibration and perform low-disturbance blasting and vibration-controlled construction during blasting construction of tunnels in fractured zones. It is necessary to find a construction method that not only ensures construction quality and progress, but also minimizes the impact of tunnel blasting construction on itself, surrounding rock and other structures. Summary of the Invention

[0004] To achieve these objectives and other advantages according to the present invention, a preferred embodiment of the present invention provides a method for low-disturbance blasting and vibration-controlled construction of a tunnel including a pilot tunnel in a fractured zone, comprising the following steps:

[0005] S1. In the tunnel fracture zone, the tunnel face is divided from the inside out into a blasting area and a non-blasting area. The non-blasting area is excavated from the middle of the tunnel face to form a pilot hole. While the pilot hole is being excavated, the arch pipe shed and the outline advance small guide pipe drilling are carried out.

[0006] S2. Excavate the blasting area and simultaneously drill holes for the arch pipe shed and the contour-advanced small guide tube;

[0007] S3. After the arch pipe shed and the outline of the advanced small pipe in the area to be blasted are drilled, the pipe shed and the advanced small pipe are pushed into the hole without grouting to form a vibration reduction hole group belt;

[0008] S4. Performing sequential blasting excavation on the blasting area, and performing grouting reinforcement on the arch pipe shed and the outline advance small guide pipe in stages during the blasting excavation process.

[0009] Preferably, in S4, sequential blasting excavation is performed on the blasting area, and during the blasting excavation process, grouting reinforcement is performed on the arch pipe shed 6 and the contour advance small conduit in stages, specifically including the following steps:

[0010] S41. The blasting area is symmetrically divided into two arc-shaped strips, which are distributed from farthest away from the tunnel excavation contour to closer to the contour;

[0011] S42. First blast the arc-shaped strip farthest from the tunnel excavation outline. After blasting, ventilate and remove the slag and dangerous goods.

[0012] S43. Then, the first stage of low-pressure grouting is carried out on the arch pipe shed and the small pipe ahead of the outline. The grouting pressure is 0.3-0.8 MPa to fill the large pores and form a preliminary reinforcement skeleton.

[0013] S44: After the grouting slurry has initially solidified, blast the arc strip that is the second farthest away. After blasting, ventilate the area again to remove the slag and discharge the dangerous goods.

[0014] S45. Finally, the second stage of high-pressure grouting is carried out on the arch pipe shed and the contour advance small duct. The grouting pressure is 0.8~1.5MPa to fill the tiny cracks and improve the density.

[0015] Preferably, in S43, the first stage low-pressure grouting is performed on the arch pipe shed and the contour advance small conduit, and the second-farthest arc strip 3 is drilled. After the grouting slurry is initially set, the drilling and blasting of the second-farthest arc strip is completed.

[0016] Preferably, the first stage low-pressure grouting adopts single-liquid slurry with a water-cement ratio of 1:1 to 1:0.8; the second stage high-pressure grouting adopts double-liquid slurry with water glass added and a water-cement ratio of 1:0.6.

[0017] Preferably, the external insertion angle of the arch pipe shed is 3° to 5°, and the depth is not less than 10 meters; the external insertion angle of the contour-advanced small duct 7 is 10° to 15°, and the longitudinal overlap length is ≥1.0 meter.

[0018] Preferably, the blasting adopts a hole-by-hole micro-difference initiation network, with a time difference of 9 milliseconds between holes and a time difference of 50 milliseconds between rows.

[0019] Preferably, before each blasting, the vibration wave velocity of the vibration-damping hole group is tested, and the grouting parameters and blasting parameters of the next stage are dynamically adjusted according to the test results.

[0020] Preferably, before each blasting, the vibration wave velocity of the vibration-damping hole group is tested, and the grouting parameters and blasting parameters of the next stage are dynamically adjusted according to the test results, which specifically includes the following steps:

[0021] A. Arrange acoustic wave transmitters and receivers between adjacent pipe racks;

[0022] B. Measure the propagation velocity Vp of the elastic wave in the vibration-damping hole cluster and calculate the wave velocity attenuation rate η = (Vp0-Vp) / Vp0×100%, where Vp0 is the initial wave velocity reference value;

[0023] C. Dynamically adjust construction parameters based on test results:

[0024] When η>15%, increase the next grouting pressure by 0.2-0.4 MPa and reduce the next blasting charge by 15%-20%;

[0025] When 8%≤η≤15%, maintain the original grouting pressure but extend the time difference between micro-difference detonation and rowing to 70-100ms;

[0026] When η<8%, construction shall be carried out according to the original design parameters.

[0027] Preferably, the vibration wave velocity test is completed within 24 hours before blasting, the distance between the test points is no more than 2m, and each test section has no less than 5 groups of measuring points.

[0028] The present invention has at least the following beneficial effects:

[0029] 1. The low-disturbance blasting and vibration-controlled construction method including a pilot tunnel provided by the present invention can realize blasting excavation in tunnels with poor surrounding rock and fractured and broken zones. Compared with existing technologies, the tunnel face is excavated in multiple circular strips, which has little disturbance to the surrounding rock and ensures the safety performance of the construction.

[0030] 2. The pilot hole provided by this invention provides an excellent open surface for subsequent blasting, minimizing rock inclusions. The open surface gradually increases with strip excavation. The blastholes are arranged parallel to the open surface, resulting in a small charge and a large open surface. This helps fully utilize the explosive energy to break the rock, minimizes disturbance to the surrounding rock, and reduces harmful effects such as vibration, flying rocks, and noise from the blasting, thus promoting the stability of the fracture zone.

[0031] 3. After the arch pipe shed and the small, advanced-profile conduit provided by the present invention are bored, the grouting pipe is only advanced without grouting before the second blast. This creates a vibration-damping hole cluster, reducing vibration propagation. Subsequent grouting is performed in stages. The first stage involves low-pressure grouting to fill large cracks and initially form a reinforced skeleton. The second stage involves high-pressure grouting to fill small cracks, repair blast-induced cracks, increase density, and protect the rock mass surrounding the excavation outline.

[0032] 4. Considering the two major pain points of traditional broken zone tunnel blasting construction: the uncontrollable propagation of blasting vibration; the weak surrounding rock is sensitive to vibration and easily causes landslides; the grouting reinforcement is disconnected from the blasting disturbance; and the static grouting parameters cannot adapt to the dynamic surrounding rock damage after blasting. To address this problem, the present invention performs vibration wave velocity detection on the vibration-damping hole group before each blasting, and dynamically adjusts the grouting parameters and blasting parameters of the next stage based on the detection results. Through real-time feedback of the wave velocity attenuation rate η, the charge amount and detonation sequence are dynamically adjusted to control the vibration speed within the specified range.

[0033] Other advantages, objectives and features of the present invention will be reflected in part from the following description and will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a schematic diagram of the zoning and block division of the tunnel face blasting / non-blasting excavation area of the present invention;

[0035] Figure 2 This is the tunnel face advance support measure of the present invention;

[0036] Figure 3 This is the layout of the blastholes and the detonation network diagram for the blasting excavation area ② of the present invention;

[0037] Figure 4 This is the layout of the blastholes and the detonation network diagram for the blasting excavation area ③ of the present invention;

[0038] Figure 5 This is a cross-sectional view of the tunnel operation of the present invention.

[0039] Figure numbers: 1 is the non-blasting area ①; 2 is the arc strip of the blasting area ②; 3 is the arc strip of the blasting area ③; 4 is the excavation outline of the non-blasting area; 5 is the tunnel excavation outline; 6 is the arch pipe shed; 7 is the tunnel advance guide tube; 8 is the blast hole position. DETAILED DESCRIPTION

[0040] The present invention will be described in further detail below in conjunction with the accompanying drawings so that those skilled in the art can implement the invention with reference to the description.

[0041] The following description is intended to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments described below are for illustrative purposes only, and those skilled in the art will readily appreciate other obvious variations. The basic principles of the present invention defined in the following description may be applied to other embodiments, variations, improvements, equivalents, and other technical solutions that do not depart from the spirit and scope of the present invention.

[0042] Those skilled in the art should understand that, in the disclosure of the present invention, the terms "longitudinal", "transverse", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like to indicate orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the above terms should not be understood as limiting the present invention.

[0043] It is to be understood that the term "one" should be understood as "at least one" or "one or more", that is, in one embodiment, the number of an element may be one, while in another embodiment, the number of the elements may be multiple, and the term "one" should not be understood as a limitation on the quantity.

[0044] like Figure 1-5 As shown, a preferred embodiment of the present invention provides a method for low-disturbance blasting and vibration-controlled construction of a broken zone tunnel including a pilot tunnel, comprising the following steps:

[0045] S1. In the tunnel fracture zone, the tunnel face is divided from the inside out into a blasting area and a non-blasting area①. The non-blasting area is formed by excavating a pilot hole in the middle of the tunnel face. Simultaneously with the pilot hole excavation, the arch pipe shed and contour advance small guide pipe drilling are carried out.

[0046] S2, excavation construction is carried out on the blasting area, and drilling construction of the arch pipe shed 6 and the contour advanced small guide tube 7 is carried out simultaneously;

[0047] S3, after the arch pipe shed 6 and the outline advance small guide tube 7 in the area to be blasted are drilled, the pipe shed and the advance small guide tube are pushed into the hole without grouting to form a vibration reduction hole group belt;

[0048] S4. Perform blasting excavation in sequence on the blasting area, and perform grouting reinforcement on the arch pipe shed 6 and the contour-advanced small guide tube 7 in stages during the blasting excavation process.

[0049] The core of the above technical solution is to form an air-facing surface through a pilot hole and coordinate with the vibration-reducing hole group to disperse stress waves, thereby achieving low-disturbance blasting, reducing the blasting vibration peak by more than 30%, and controlling the surrounding rock disturbance depth within 1.5m.

[0050] During implementation, the non-blasting area is located in the middle of the tunnel face. Mechanical excavation is used to form a pilot hole 1 with a non-blasting area excavation outline 4. During this excavation process, the arched pipe shed 6 and the small guiding pipe 7, which are ahead of the outline, are drilled simultaneously. The blasting area is symmetrically distributed on both sides of the pilot hole 1, divided into arc-shaped strips 2 and 3. After the pipe shed 6 and the small guiding pipe 7 are drilled, they are pushed into the holes without grouting, forming a vibration-damping hole cluster. A water drill or hydraulic breaker is used to excavate the pilot hole 1, with a width and height of 4-5 meters.

[0051] In another technical solution, in S4, the blasting area is excavated by sequential blasting, and the arch pipe shed 6 and the contour advance small guide tube 7 are reinforced by grouting in stages during the blasting excavation process, which specifically includes the following steps:

[0052] S41, symmetrically dividing the blasting area into two arc-shaped strips, distributed sequentially from farthest from the tunnel excavation contour 5 to closer to the contour;

[0053] S42, first blast the arc strip 2 farthest from the tunnel excavation outline 5, and after blasting, ventilate and remove the slag and danger;

[0054] S43, then perform the first stage of low-pressure grouting on the arch pipe shed 6 and the contour advance small conduit 7, with a grouting pressure of 0.3-0.8 MPa, to fill the large pores and form a preliminary reinforcement skeleton;

[0055] S44, after the grouting slurry has initially solidified, blast the second-farthest arc strip 3, and after blasting, ventilate again to remove slag and discharge hazards;

[0056] S45. Finally, the second stage of high-pressure grouting is performed on the arch pipe shed 6 and the contour advance small guide tube 7. The grouting pressure is 0.8-1.5 MPa to fill the tiny cracks and improve the density.

[0057] In the above technical solution, the first stage is low-pressure grouting (0.3-0.8 MPa), using a single-liquid slurry (water-cement ratio of 1:1-1:0.8) to fill the large pores generated by blasting. After the slurry initially solidifies to form a preliminary skeleton, the second-farthest strip (3) is blasted, and finally the second stage is high-pressure grouting (0.8-1.5 MPa), using a double-liquid slurry (water-cement ratio of 1:0.6) with water glass added to close the microcracks. The two-stage grouting forms a gradient reinforcement structure: the low-pressure grouting body has a compressive strength of 15 MPa to ensure initial stability, and the overall strength is increased to 25 MPa after high-pressure grouting. The bearing capacity of the support structure is increased by 30%, and the initial support sealing time is shortened to 6 hours.

[0058] Furthermore, drilling operations in Strip 3 were carried out simultaneously during the low-pressure grouting phase. The coordinated optimization of blasting and grouting, through the precise coordination of sequential blasting and staged grouting, formed a closed-loop control system of "blasting damage, low-pressure filling, secondary blasting, and high-pressure repair." This improved the repair rate of blast-induced cracks and controlled the surrounding rock disturbance depth to within 1.2m.

[0059] In another technical solution, in S43, the first stage of low-pressure grouting is performed on the arch pipe scaffold 6 and the contour advance small guide tube 7. The next-most distant curved strip 3 is drilled. After the grouting slurry has initially set, the drilling and blasting of the next-most distant curved strip is completed. The grouting and drilling equipment are located on either side of the tunnel face to avoid interference.

[0060] In another technical solution, the first stage low-pressure grouting uses single-liquid slurry with a water-cement ratio of 1:1 to 1:0.8; the second stage high-pressure grouting uses double-liquid slurry with water glass added and a water-cement ratio of 1:0.6.

[0061] A higher water-cement ratio (1:1 to 1:0.8) is used in the single-liquid slurry large pore filling stage to ensure that the slurry penetration radius reaches 2.5m; the high-pressure grouting stage greatly shortens the micro-crack filling time through the rapid setting characteristics of the double-liquid slurry.

[0062] In another technical solution, the external insertion angle of the arch pipe scaffold 6 is 3° to 5°, and the depth is not less than 10 meters; the external insertion angle of the contour-advanced small duct 7 is 10° to 15°, and the longitudinal overlap length is ≥1.0 meter.

[0063] Another technical solution uses a hole-by-hole differential initiation network, with a 9 millisecond time difference between holes and a 50 millisecond time difference between rows. During wiring, detonators in the same row of holes (8) are connected in parallel and then in series to the initiator, ensuring independent detonation timing for each hole. Using hole-by-hole differential initiation can reduce blasting vibration accumulation by 40%.

[0064] There are two major pain points in traditional tunnel blasting construction in broken zones: first, the weak surrounding rock is sensitive to vibration, which can easily cause landslides, and the propagation of blasting vibration is uncontrollable; second, the static grouting parameters cannot adapt to the dynamic surrounding rock damage after blasting, and the grouting reinforcement is disconnected from the blasting disturbance. To address this situation, the present application provides a method, which specifically performs vibration wave velocity detection on the vibration-damping hole group before each blasting, and dynamically adjusts the grouting parameters and blasting parameters for the next stage based on the detection results.

[0065] Before each blasting, the vibration wave velocity of the vibration-damping hole group is tested, and the grouting parameters and blasting parameters of the next stage are dynamically adjusted according to the test results. The specific steps include:

[0066] A. Arrange acoustic wave transmitters and receivers between adjacent pipe racks 6;

[0067] B. Measure the propagation velocity Vp of the elastic wave in the vibration-damping hole cluster and calculate the wave velocity attenuation rate η = (Vp0 - Vp) / Vp0 × 100%, where Vp0 is the initial wave velocity reference value, which needs to be determined through preliminary geological exploration or test sections;

[0068] C. Dynamically adjust construction parameters based on test results:

[0069] When η>15%, it is judged as a surrounding rock damage area, and the next grouting pressure needs to be increased by 0.2~0.4MPa (if it is low-pressure grouting, adjust it to 0.5~1.2MPa, if it is high-pressure grouting, adjust it to 1.0~1.9MPa), and the next blasting charge should be reduced by 15%~20%; dynamic detection is used to identify the surrounding rock damage area (η>15% area), and the grouting pressure is increased in a targeted manner, so that the slurry penetration radius increases by 40%, and the explosive crack filling rate is increased from 75% to 92%.

[0070] When 8%≤η≤15%, maintain the original grouting pressure but extend the time difference between micro-difference detonation rows to 70-100ms, so that the blasting vibration speed can be reduced from 2.5cm / s to 1.8cm / s; the vibration reduction hole group and blasting speed adjustment work together to compress the surrounding rock disturbance depth from 2.0m to 1.2m.

[0071] When η<8%, construction shall be carried out according to the original design parameters.

[0072] In another technical solution, vibration wave velocity testing is completed within 24 hours before blasting, with testing points spaced no more than 2 meters apart and no fewer than five groups of testing points per test section. Testing points are evenly spaced across the section, and multiple data sets are averaged to ensure reliable test results.

[0073] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the description and implementation methods. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A low-disturbance blasting and vibration-controlled construction method for a broken zone tunnel including a pilot tunnel, characterized in that: The following steps are involved: S1. In the tunnel fracture zone, the tunnel face is divided from the inside out into a blasting area and a non-blasting area. The non-blasting area is excavated from the middle of the tunnel face to form a pilot hole. While the pilot hole is being excavated, the arch pipe shed and the outline advance small guide pipe drilling are carried out. S2. Excavate the blasting area and simultaneously drill holes for the arch pipe shed and the contour-advanced small guide tube; S3. After the arch pipe shed and the outline of the advanced small pipe in the area to be blasted are drilled, the pipe shed and the advanced small pipe are pushed into the hole without grouting to form a vibration reduction hole group belt; S4. Excavating the blasting area by blasting in sequence, and reinforcing the arch pipe shed and the outline-advanced small guide tube by grouting in stages during the blasting excavation process.

2. The low-disturbance blasting and vibration-controlled construction method for a broken zone tunnel including a pilot tunnel according to claim 1 is characterized in that: In S4, sequential blasting excavation is performed on the blasting area, and during the blasting excavation process, the arch pipe shed 6 and the contour advance small pipe are reinforced by grouting in stages, which specifically includes the following steps: S41. The blasting area is symmetrically divided into two arc-shaped strips, which are distributed from farthest away from the tunnel excavation contour to closer to the contour; S42. First blast the arc-shaped strip farthest from the tunnel excavation outline. After blasting, ventilate and remove the slag and dangerous goods. S43. Then, the first stage of low-pressure grouting is carried out on the arch pipe shed and the small pipe ahead of the outline. The grouting pressure is 0.3-0.8 MPa to fill the large pores and form a preliminary reinforcement skeleton. S44: After the grouting slurry has initially solidified, blast the arc strip that is the second farthest away. After blasting, ventilate the slag again and remove the danger. S45. Finally, the second stage of high-pressure grouting is carried out on the arch pipe shed and the contour advance small duct. The grouting pressure is 0.8~1.5MPa to fill the tiny cracks and improve the density.

3. The low-disturbance blasting and vibration-controlled construction method for a broken zone tunnel including a pilot tunnel according to claim 2 is characterized in that: In S43, the first stage of low-pressure grouting was carried out on the arch pipe shed and the small conduit ahead of the contour, and the second-farthest arc strip 3 was drilled.

4. The low-disturbance blasting and vibration-controlled construction method for a broken zone tunnel including a pilot tunnel according to claim 2 is characterized in that: The first stage low-pressure grouting uses single-liquid slurry with a water-cement ratio of 1:1 to 1:0.8; the second stage high-pressure grouting uses double-liquid slurry, to which water glass is added, with a water-cement ratio of 1:0.6, and cement slurry: water glass = 1:0.5 to 1:0.

8.

5. The low-disturbance blasting and vibration-controlled construction method for a broken zone tunnel including a pilot tunnel according to claim 1 is characterized in that: The external insertion angle of the arch pipe shed is 3° to 5°, and the depth is not less than 10 meters; the external insertion angle of the outline-advanced small duct 7 is 10° to 15°, and the longitudinal overlap length is ≥1.0 meter.

6. The low-disturbance blasting and vibration-controlled construction method for a broken zone tunnel including a pilot tunnel according to claim 1 is characterized in that: The blasting adopts a hole-by-hole micro-difference initiation network, with a time difference of 9 milliseconds between holes and 50 milliseconds between rows.

7. The low-disturbance blasting and vibration-controlled construction method for a broken zone tunnel including a pilot tunnel according to claim 1 is characterized in that: Before each blasting, the vibration wave velocity of the vibration-damping hole group is tested, and the grouting parameters and blasting parameters of the next stage are dynamically adjusted according to the test results.

8. The low-disturbance blasting and vibration-controlled construction method for a broken zone tunnel including a pilot tunnel according to claim 7 is characterized in that: Before each blasting, the vibration wave velocity of the vibration-damping hole group is tested, and the grouting parameters and blasting parameters of the next stage are dynamically adjusted according to the test results. The specific steps include: A. Arrange acoustic wave transmitters and receivers between adjacent pipe racks; B. Measure the propagation velocity Vp of the elastic wave in the vibration-damping hole cluster and calculate the wave velocity attenuation rate η = (Vp0-Vp) / Vp0×100%, where Vp0 is the initial wave velocity reference value; C. Dynamically adjust construction parameters based on test results: When η>15%, increase the next grouting pressure by 0.2-0.4 MPa and reduce the next blasting charge by 15%-20%; When 8%≤η≤15%, maintain the original grouting pressure but extend the time difference between micro-difference detonation and rowing to 70-100ms; When η<8%, construction shall be carried out according to the original design parameters.

9. The low-disturbance blasting and vibration-controlled construction method for a broken zone tunnel including a pilot tunnel according to claim 7 is characterized in that: The vibration wave velocity test shall be completed within 24 hours before blasting, the distance between the test points shall not exceed 2m, and each test section shall have no less than 5 groups of measuring points.

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