Method for determining blasting vibration control standard of early age concrete lining of tunnel

Abstract

The application discloses a kind of tunnel early age concrete lining's blasting vibration control standard determination method, including determining initial safety blast center distance in blasting vibration test scheme, making and carrying out the blasting vibration test scheme of tunnel engineering, processing the test data of blasting vibration test scheme, predicting the maximum value of each measuring point's cumulative damage, solving the minimum safety blast center distance corresponding to critical cumulative damage threshold, fitting the dominant blasting vibration peak velocity model of tunnel early age concrete lining and solving the maximum safety blasting vibration peak velocity of tunnel early age concrete lining several steps.The application can more scientifically and reasonably guide tunnel engineering construction, effectively control the blasting vibration effect of tunnel early age concrete lining structure, and protect the safety of surrounding rock-lining structure under repeated blasting construction operation conditions of tunnel engineering.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of tunnel blasting vibration effect control, and particularly relates to a method for determining a blasting vibration control standard of early-age concrete lining of a tunnel. BACKGROUND

[0002] As the most widely used construction method for tunnel excavation, drilling and blasting technology has also ushered in more broad development opportunities with the large-scale development of tunnel construction. When drilling and blasting method is used for tunnel construction, in addition to only about 20-30% of the blasting energy being used for rock breaking to form a tunnel, the remaining blasting energy inevitably causes a series of blasting harmful effects, such as blasting vibration, overpressure, flying stone, dust, etc., and the blasting vibration effect, which is considered as the "first blasting hazard", has received widespread attention and emphasis. In the actual tunnel engineering construction process, due to the intersection of working faces or progress requirements, the tunnel blasting operation and the concrete lining pouring are simultaneously performed in a short distance. The early-age concrete lining has low strength, and the blasting vibration caused by the tunnel blasting operation can cause the cement paste and aggregate to crack, and even form through cracks, thereby affecting the late strength growth of the concrete and damaging the quality of the concrete lining. In addition, frequent blasting operations can cause cumulative damage to the surrounding rock and the lining structure, resulting in deterioration of the mechanical properties of the surrounding rock and the lining structure, reduction of the strength, and deterioration of the integrity, and the stability of the tunnel surrounding rock will be affected or even seriously threatened.

[0003] Since the existing blasting vibration safety allowable standard is developed for the vibration effect of early-age concrete lining structure under the action of single blasting load, the cyclic blasting (action) advancing process during the actual excavation of the tunnel by drilling and blasting method is not considered, that is, the cumulative damage of the lining (and surrounding rock) structure is not considered. In addition, the same control standard is given for all early-age concrete linings of tunnel engineering by the standard, without considering the differences existing in different tunnel engineering, and without considering the differences in the surrounding rock grade and actual state of the same tunnel engineering. Therefore, the standard cannot completely guide the tunnel engineering site construction, and the damage and even collapse accidents of early-age concrete lining caused by tunnel blasting operation occur from time to time. Based on this, it is necessary to propose a more scientific and reasonable method for determining the blasting vibration control standard of early-age concrete lining of a tunnel, to guide and ensure the safe and efficient construction of the tunnel blasting engineering. SUMMARY

[0004] The present application aims to provide a method for determining a blasting vibration control standard of early-age concrete lining of a tunnel, to solve one of the problems raised in the background.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0006] The application discloses a method for determining a blasting vibration control standard of early-age concrete lining of a tunnel, and relates to the technical field of tunnel engineering.

[0007] Step 1: determining an initial safe blast center distance in a blasting vibration test scheme

[0008] Step 2: formulating and implementing a blasting vibration test scheme of a tunnel project

[0009] The blasting vibration test scheme is implemented before a blasting scheme of the tunnel project, a sound wave measuring point is arranged at a position of early-age concrete lining of a tunnel side rock waist at a distance of R0 from an excavation face, the sound wave measuring point is taken as a minimum blast center distance base point, a plurality of sound wave measuring points are arranged in a reverse direction of tunneling, and an average value of multiple wave velocity values measured at each sound wave measuring point is taken as a longitudinal wave velocity of each sound wave measuring point.

[0010] A vibration measuring point is arranged at a position of early-age concrete lining directly above each sound wave measuring point, a blasting vibration tester is arranged at each vibration measuring point, and vertical, horizontal radial and horizontal tangential blasting vibration peak values at each vibration measuring point are tested.

[0011] The blasting vibration test scheme is implemented and repeated n times, the longitudinal wave velocity c 0j of each sound wave measuring point before the first blasting is calculated and recorded, the longitudinal wave velocity c ij of each sound wave measuring point after each blasting is calculated and recorded, and the vertical, horizontal radial and horizontal tangential blasting vibration peak values v vj , v rj and v tj at each vibration measuring point during the first blasting are recorded; wherein j is a measuring point serial number, i is a blasting frequency of the test scheme, and i = 1, 2, …, n.

[0012] Step 3: processing test data of the blasting vibration test scheme

[0013] Based on the tested longitudinal wave velocity data, the cumulative damage of each sound wave measuring point after each blasting is calculated according to the following formula:

[0014]

[0015] Based on the tested vertical, horizontal radial and horizontal tangential blasting vibration peak values at each vibration measuring point during the first blasting, the maximum peak value in the three directions of each vibration measuring point is taken as the dominant blasting vibration peak value of each vibration measuring point during the first blasting, and is recorded as v dj .

[0016] Step 4: predicting a maximum value of the cumulative damage of each measuring point

[0017] Based on the blasting action times and the corresponding cumulative damage data (i, Dj) of each acoustic wave measuring point, the model of cumulative damage Dj versus blasting action times i of each measuring point is fitted in the form of the following equation: ij

[0018] D j = A 0j + A 1j i + A 2j i2+ A 2 i3(3)

[0019] In the equation, Dj is the cumulative damage of the jth measuring point; i is the blasting action times; A j , A 0j , A 1j , and A 2j are the model fitting coefficients of the jth measuring point.

[0020] Then, based on the fitted model Dj(i) of cumulative damage versus blasting action times i of each measuring point, the maximum value of cumulative damage of each measuring point is further predicted, denoted as Djmax. j

[0021] Step 5, solving the minimum safe distance from the blast center corresponding to the critical cumulative damage threshold mj

[0022] Based on the data of the maximum values of cumulative damage and the corresponding initial distances from the blast center of all measuring points, the minimum safe distance from the blast center [R min ] is solved when the maximum value of cumulative damage takes the critical cumulative damage threshold 0.19.

[0023] Step 6, fitting the model of the dominant blasting vibration peak velocity of the early-age concrete lining of the tunnel;

[0024] Based on the dominant blasting vibration peak velocity v dj , the initial distance from the blast center, and the maximum charge amount per segment of the tunnel blasting of all vibration measuring points during the first blasting action, the model of the dominant blasting vibration peak velocity of the early-age concrete lining of the tunnel surrounding rock segment is fitted in the form of the following Sadaev equation:

[0025]

[0026] In the equation, R is the initial distance from the blast center of each measuring point, m; Q is the maximum charge amount per segment of the tunnel blasting, kg; k and a are the peak velocity fitting coefficients related to the state of the tunnel engineering surrounding rock-lining structure and the topographic and geological conditions.

[0027] Step 7, solving the maximum safe blasting vibration peak velocity of the early-age concrete lining of the tunnel;

[0028] ​​​The minimum safe blast center distance corresponding to the critical cumulative damage threshold value solved in step 5 and the maximum explosive charge of a single section of the tunnel blasting are substituted into the Satchell formula (4) fitted in step 6, and the peak vibration velocity of the dominant blasting solved is the maximum safe blasting peak vibration velocity of the early age concrete lining of the tunnel surrounding rock section.

[0029] Specifically, for the tunnel blasting project including early age concrete linings of different levels of surrounding rock sections, steps 1-7 can be repeated for the early age concrete lining of another level of surrounding rock section, so that the maximum safe blasting peak vibration velocity of the early age concrete lining of the other different level of surrounding rock section of the tunnel project can be determined.

[0030] Specifically, the number of sound wave measuring points is not less than 5, and the distance between adjacent sound wave measuring points is 2-8 m.

[0031] Specifically, the initial safe blast center distance in the blasting vibration test scheme is determined by the following formula:

[0032] R0≥4D0 (1)

[0033] In the formula, D0 is the tunnel diameter, m.

[0034] Specifically, the sound wave test adopts a single-hole sound wave method, a transmitting and receiving transducer is used to test in the measuring hole of the sound wave measuring point, and the transmission and reception are performed in the same measuring hole, and water is injected in the measuring hole as a coupling medium for the probe transducer.

[0035] Specifically, the measuring hole has a depth of 1.5-2 m, and during the test process, the transmitting and receiving transducer is placed at the bottom of the measuring hole, and 3-5 tests are performed from the bottom upwards.

[0036] Specifically, a vibration measuring point is arranged at a position of the early age concrete lining 0.5-1 m directly above each sound wave measuring point.

[0037] Specifically, the least square method is used to fit the peak vibration velocity model of the dominant blasting of the early age concrete lining of the tunnel surrounding rock section according to the Satchell formula form.

[0038] Specifically, the least square method is used to fit the peak vibration velocity model of the dominant blasting of the early age concrete lining of the tunnel surrounding rock section according to the Satchell formula form.

[0039] Specifically, n is greater than or equal to 10.

[0040] Compared with the prior art, at least one embodiment of the present application has the following beneficial effects:

[0041] (1) The tunnel early-age concrete lining blasting vibration control standard determination method provided by the application not only considers the cumulative damage effect of different tunnel engineering early-age concrete lining structures under cyclic blasting, but also considers the dynamic degradation process of the early-age concrete lining structure of the specific tunnel engineering section of different grades of surrounding rock, which can more scientifically and reasonably guide the tunnel engineering construction, effectively control the blasting vibration effect of the tunnel early-age concrete lining structure, and ensure the safety of the surrounding rock-lining structure of the tunnel engineering under the repeated blasting construction operation condition.

[0042] (2) By using the method, the single-section maximum explosive charge in the tunnel engineering blasting scheme can be optimized to the maximum value by the Saylor formula, and the blasting construction efficiency is maximized under the premise of ensuring the safety of the early-age concrete lining structure of the tunnel within the safe blasting distance and under the repeated blasting construction operation condition.

[0043] (3) The method has clear steps and is simple to implement, and only needs to arrange a plurality of sound wave measuring points and collect sound wave test data under several times of blasting action, and arrange a plurality of vibration measuring points and collect vibration test data once for the early-age concrete lining of the tunnel section of different grades of surrounding rock before the implementation of the tunnel engineering blasting scheme; the method does not need to be tracked and tested on site during the tunnel construction, has less test workload, low test cost, strong applicability and promotion value. BRIEF DESCRIPTION OF DRAWINGS

[0044] Figure 1 The figure is a flowchart of the method of the application;

[0045] Figure 2 The figure is a schematic diagram of the measuring point arrangement of the embodiment of the application. DETAILED DESCRIPTION

[0046] A tunnel early-age concrete lining blasting vibration control standard determination method, comprising the following steps:

[0047] Step 1, determining the initial safe blasting distance in the blasting vibration test scheme.

[0048] The initial safe blasting distance in the blasting vibration test scheme is determined by the following formula:

[0049] R0≥4D0 (1)

[0050] In the formula, D0 is the tunnel diameter, m.

[0051] Step 2, formulating and carrying out the blasting vibration test scheme of the tunnel engineering.

[0052] The blasting vibration test scheme is carried out in the early stage of the blasting scheme of the tunnel project. A sound wave measuring point is arranged at the early age concrete lining position of the tunnel side surrounding rock hance with a distance of R0 from the excavation face. The sound wave measuring point is taken as the minimum blast center distance base point, and not less than 5 sound wave measuring points are arranged along the reverse direction of the excavation with a distance of 2-8 m between adjacent sound wave measuring points.

[0053] The single-hole sound wave method is recommended for the sound wave test. The one-transmitting and double-receiving transducer is used for the test in the sound wave measuring hole. The transmitting and receiving are carried out in the same hole, and the water in the hole is used as the coupling medium of the probe transducer. The hole depth of the sound wave measuring hole is recommended to be 1.5-2 m. During the test, the one-transmitting and double-receiving transducer is placed at the bottom of the hole, and 3-5 tests are carried out from the bottom to the top. The average value of the wave velocity values measured in each sound wave measuring hole is taken as the longitudinal wave velocity of each sound wave measuring point. A vibration measuring point is arranged at the early age concrete lining position 0.5-1 m above each sound wave measuring point. A blasting vibration tester and its supporting vertical direction, horizontal radial direction and horizontal tangential direction velocity sensors are arranged at each vibration measuring point to test the three-direction blasting vibration peak velocities at each vibration measuring point.

[0054] The blasting vibration test scheme is carried out repeatedly for n (n≥10) times, and the longitudinal wave velocity c 0j of each sound wave measuring point before the first blasting is calculated and recorded (j is the measuring point serial number), and the longitudinal wave velocity c ij of each sound wave measuring point after each blasting is calculated and recorded (i is the blasting action number of the test scheme, i=1, 2, …, n), and the vertical direction, horizontal radial direction and horizontal tangential direction blasting vibration peak velocities v vj , v rj and v tj at each vibration measuring point during the first blasting are recorded.

[0055] Step 3, processing the test data of the blasting vibration test scheme.

[0056] Based on the tested longitudinal wave velocity data, the cumulative damage of each sound wave measuring point after each blasting is calculated according to the following formula:

[0057]

[0058] Based on the tested vertical direction, horizontal radial direction and horizontal tangential direction blasting vibration peak velocity data of each vibration measuring point during the first blasting, the maximum peak velocity value in the three directions of each vibration measuring point is taken as the dominant blasting vibration peak velocity of each vibration measuring point during the first blasting, which is denoted as v dj .

[0059] Step 4, predicting the maximum value of the cumulative damage of each measuring point.

[0060] First, based on the number of blasting actions and the corresponding cumulative damage data (i, D) at each acoustic measurement point. ij The cumulative damage at each measuring point is fitted with respect to the number of blasting actions according to the following formula:

[0061] D j =A 0j +A 1j I+A 2j I 2 (3)

[0062] In the formula, D j The cumulative damage at the j-th measuring point; I represents the number of blasting actions; A 0j A 1j A 2j The model fitting coefficients are for the j-th measurement point.

[0063] Then, based on the fitted model D of the cumulative damage at each measuring point with respect to the number of blasting actions... j (I) Further predict (solve) the maximum cumulative damage at each measuring point, denoted as D. mj .

[0064] Step 5: Solve for the minimum safe burst center distance corresponding to the critical cumulative damage threshold.

[0065] Based on the data consisting of the maximum cumulative damage value and the corresponding initial detonation distance at all measuring points, the minimum safe detonation distance [R] when the maximum cumulative damage value is taken as the critical cumulative damage threshold of 0.19 is solved using the cubic spline interpolation method. min ].

[0066] Step 6: Fit the peak velocity model of blasting vibration for early-age concrete lining of the tunnel.

[0067] Based on the superior peak velocity v of the blasting vibration at all vibration measurement points during the first blasting operation. dj The initial blast center distance and the maximum charge per segment of tunnel blasting were used to fit the dominant peak blasting vibration velocity model of the early-age concrete lining in the surrounding rock section of the tunnel using the least squares method and the following Sachs formula:

[0068]

[0069] In the formula, R is the initial blast center distance at each measuring point, m; Q is the maximum charge per segment of tunnel blasting, kg; k and α are the peak velocity fitting coefficients related to the state of the surrounding rock-lining structure and the topographic and geological conditions of the tunnel project.

[0070] Step 7: Determine the maximum safe peak velocity of blasting vibration in the early-age concrete lining of the tunnel.

[0071] The minimum safe blast center distance corresponding to the critical cumulative damage threshold solved in step 5 and the maximum explosive charge of a single section of the tunnel blasting are substituted into the Satchell formula (4) fitted in step 6, and the peak velocity of the dominant blasting vibration solved is the maximum safe blasting vibration peak velocity of the early age concrete lining of the tunnel surrounding rock section.

[0072] For a tunnel blasting project containing early age concrete linings of different levels of surrounding rock sections, steps 1-7 can be repeated for the early age concrete lining of another level of surrounding rock section to determine the maximum safe blasting vibration peak velocity of the early age concrete lining of the other different level of surrounding rock section of the tunnel project.

[0073] Embodiment

[0074] The scheme of the present application will be further described below in combination with specific embodiments.

[0075] Reference Figure 1 and Figure 2 A method for determining a blasting vibration control standard of a tunnel early age concrete lining, comprising the following steps:

[0076] Step 1, determining an initial safe blast center distance in a blasting vibration test scheme.

[0077] The diameter of a certain tunnel project is 6.5m, the surrounding rock level of the main tunnel includes Ⅲ, Ⅳ and Ⅴ levels, and the molded concrete is used as the secondary lining. First, the blasting vibration control standard is determined for the concrete lining with an age of 6 days in the Ⅲ level surrounding rock section using full-face excavation.

[0078] The initial safe blast center distance R0≥26m in the blasting vibration test scheme is determined by formula (1), and R0=30m is taken.

[0079] Step 2, developing a blasting vibration test scheme for the tunnel project.

[0080] The blasting vibration test scheme is carried out in the early stage of the blasting scheme implementation of the tunnel engineering. A sound wave measuring point is arranged at the early age concrete lining position of the tunnel side surrounding rock hance 30 m away from the excavation face. The sound wave measuring point is taken as the minimum blast center distance base point, 5 sound wave measuring points are arranged along the reverse direction of the excavation, the distance between the adjacent sound wave measuring points is 5 m, the sound wave measuring points are numbered in the reverse direction of the excavation, and are respectively denoted as S1, S2, S3, S4 and S5. The sound wave test adopts the single-hole sound wave method, the RSM-SY5 sound wave instrument and the FSS-20 type one-transmitting and double-receiving transducer are used, and water injection in the hole is used as the coupling medium of the probe. The hole depth of the sound wave measuring hole is 1.5 m, the one-transmitting and double-receiving transducer is arranged at the hole bottom in the test process, the distance (distance measurement) between the two receiving transducer probes is 20 cm, the distance between the transmitting transducer probe and the upper receiving transducer probe is 30 cm, and 4 tests are carried out from the hole bottom upwards. The average value of the 4 wave velocity values measured in each sound wave measuring hole is taken as the longitudinal wave velocity of each sound wave measuring point. A vibration measuring point is arranged at the early age concrete lining position 0.5 m above each sound wave measuring point, 5 vibration measuring points are arranged along the reverse direction of the excavation, the vibration measuring points are numbered in the reverse direction of the excavation, and are respectively denoted as Z1, Z2, Z3, Z4 and Z5. A TC-4850 blasting vibration tester and its supporting vertical direction, horizontal radial direction and horizontal tangential direction velocity sensors are arranged at each vibration measuring point, and the three-direction blasting vibration peak velocities at each vibration measuring point are tested.

[0081] The blasting vibration test scheme is carried out and repeated for 10 times, the longitudinal wave velocity c of each sound wave measuring point before the first blasting is calculated and recorded 0j (j is the measuring point serial number, j = 1, 2, 3, 4, 5), the longitudinal wave velocity c of each sound wave measuring point after each blasting is calculated and recorded ij (i is the blasting action number of the test scheme, i = 1, 2, …, 10), and the vertical direction, horizontal radial direction and horizontal tangential direction blasting vibration peak velocities v vj , v rj and v tj of each vibration measuring point in the first blasting process are recorded. Because the data is too much, it is not listed here.

[0082] Step 3, processing the test data of the blasting vibration test scheme.

[0083] Based on the tested longitudinal wave velocity data, the cumulative damage of each sound wave measuring point after each blasting is calculated according to the following formula (2), as shown in Table 1.

[0084] Table 1 is the cumulative damage data of each sound wave measuring point according to the embodiment of the application.

[0085]

[0086] Based on the tested peak velocity data of the blasting vibration in the first blasting process, the maximum peak velocity value in the horizontal tangential direction was taken as the dominant blasting vibration peak velocity of each vibration measuring point in the first blasting process (denoted as v dj ), as shown in Table 2.

[0087] Table 2 is the dominant blasting vibration peak velocity of each vibration measuring point in the first blasting process according to the embodiment of the present application.

[0088] Measurement point number Distance from blast center (m) Advantageous peak velocity of blast vibration (cm / s) Z1 30 3.65 Z2 35 2.94 Z3 40 2.19 Z4 45 1.96 Z5 50 1.64

[0089] Step 4, predicting the maximum cumulative damage of each measuring point.

[0090] Firstly, based on the blasting action times and the corresponding cumulative damage data (i, D ij ) of each acoustic wave measuring point, the cumulative damage model of each measuring point about the blasting action times was fitted according to formula (3), as shown in Table 3.

[0091] Table 3 is the fitted cumulative damage model of each measuring point about the blasting action times according to the embodiment of the present application.

[0092]

[0093]

[0094] Then, based on the fitted cumulative damage model of each measuring point about the blasting action times D j (I), the maximum cumulative damage of each measuring point was further predicted (solved), which were D m1 = 0.2670, D m2 = 0.2341, D m3 = 0.1712, D m4 = 0.1092, and D m5 = 0.0812, respectively.

[0095] Step 5, solving the minimum safe distance from the explosion center corresponding to the critical cumulative damage threshold.

[0096] Based on the five groups of data composed of the maximum cumulative damage of the five measuring points and the corresponding initial distance from the explosion center, the minimum safe distance from the explosion center [R min ] = 38.87 m when the maximum cumulative damage took the critical cumulative damage threshold 0.19 was solved by using the cubic spline interpolation method.

[0097] Step 6, fitting the dominant blasting vibration peak velocity model of the early age concrete lining of the tunnel.

[0098] Based on the dominant blasting vibration peak velocity (3.65 cm / s, 2.94 cm / s, 2.19 cm / s, 1.96 cm / s, 1.64 cm / s) of 5 vibration measuring points, initial blast center distance (30 m, 35 m, 40 m, 45 m, 50 m) and the maximum charge of single section of tunnel blasting (15.2 kg) in the first blasting process, the least square method is used to fit the dominant blasting vibration peak velocity model of the early age concrete lining of the tunnel surrounding rock section according to the form of the Satchell formula as follows:

[0099]

[0100] Step 7, solving the maximum safe blasting vibration peak velocity of the early age concrete lining of the tunnel.

[0101] The minimum safe blast center distance 38.87 m corresponding to the critical cumulative damage threshold value solved in step 5 and the maximum charge of single section of tunnel blasting 15.2 kg are substituted into the Satchell formula (4) fitted in step 6, and the dominant blasting vibration peak velocity solved is 2.41 cm / s, that is, the maximum safe blasting vibration peak velocity of the concrete lining of the tunnel III grade surrounding rock section with an age of 6 days [v max ] = 2.41 cm / s. According to the above blasting vibration control standard, the cyclic blasting operation is carried out, and the early age concrete lining of the tunnel does not have the phenomenon of blasting vibration damage and destruction.

[0102] The above examples are only examples for clearly illustrating the present application, and are not limited to the embodiments. For those skilled in the art, other different forms of changes or variations can be made on the basis of the above description. Here, all the examples are not required to be exhausted, and the obvious changes or variations derived therefrom are still within the protection scope of the present application.

Claims

1. A method for determining the blasting vibration control standard for early-age concrete lining of tunnels, characterized in that, Includes the following steps: Step 1: Determine the initial safe blast center distance in the blasting vibration test plan. Step 2: Develop and implement a blasting vibration testing plan for tunnel engineering. The blasting vibration test plan is carried out in the early stage of the tunnel engineering blasting plan. A sonic measuring point is set at the early-age concrete lining position of the surrounding rock arch waist on one side of the tunnel at a distance of R0 from the excavation face. Using this sonic measuring point as the minimum blast center distance base point, several more sonic measuring points are arranged along the opposite direction of excavation. The average value of multiple wave velocity values ​​measured at each sonic measuring point is taken as the longitudinal wave velocity of each sonic measuring point. A vibration measuring point is set at the early-age concrete lining position directly above each sound wave measuring point. A blasting vibration tester is set up at each vibration measuring point to test the peak blasting vibration velocity in the vertical, horizontal radial and horizontal tangential directions at each vibration measuring point. Conduct a blasting vibration test and repeat it n times. Calculate and record the longitudinal wave velocity c at each acoustic measurement point before the first blast. 0j Calculate and record the longitudinal wave velocity c at each acoustic measuring point after each blast. ij Simultaneously, the peak velocities v of the blasting vibration in the vertical, horizontal radial, and horizontal tangential directions at each vibration measuring point during the first blasting operation were recorded. vj v rj and v tj Where j is the measurement point number, i is the number of blasting operations carried out in the test plan, and i = 1, 2, ..., n; Step 3: Process the test data from the blasting vibration test scheme. Based on the measured longitudinal wave velocity data, the cumulative damage at each acoustic measurement point after each blasting action is calculated according to the following formula: Based on the peak blast vibration velocity data in the vertical, horizontal radial, and horizontal tangential directions at each vibration measuring point during the first blasting operation, the maximum peak velocity in each of the three directions is taken as the dominant peak blast vibration velocity at each vibration measuring point during the first blasting operation, denoted as . Step 4: Predict the maximum cumulative damage at each measuring point. Based on the number of blasting actions and the corresponding cumulative damage data (i, D) at each acoustic measurement point ij The cumulative damage at each measuring point is fitted with respect to the number of blasting actions according to the following formula: D j =A 0j +A 1j I+A 2j I 2 (3) In the formula, D j The cumulative damage at the j-th measuring point; I represents the number of blasting actions; A 0j A 1j A 2j The model fitting coefficients for the j-th measurement point; Then, based on the fitted model D of the cumulative damage at each measuring point with respect to the number of blasting actions... j (I) Further predict the maximum cumulative damage at each measuring point, denoted as D. mj ; Step 5: Solve for the minimum safe distance from the burst center corresponding to the critical cumulative damage threshold. Based on the data consisting of the maximum cumulative damage at all measuring points and the corresponding initial detonation distance, the minimum safe detonation distance [R] is calculated when the maximum cumulative damage is taken as the critical cumulative damage threshold of 0.

19. min ]; Step 6: Fit the peak velocity model of blasting vibration for early-age concrete lining of the tunnel. Based on the peak velocity of the superior blasting vibration at all vibration measurement points during the first blasting operation. The initial blast center distance and the maximum charge per segment in the tunnel blasting are used to fit the dominant peak blasting vibration velocity model of the early-age concrete lining in the surrounding rock section of the tunnel using the following Sachs formula: In the formula, R is the initial blast center distance at each measuring point, m; Q is the maximum charge per segment of tunnel blasting, kg; k and α are the peak velocity fitting coefficients related to the state of the surrounding rock-lining structure and topographic and geological conditions of the tunnel project. Step 7: Determine the maximum safe peak velocity of blasting vibration for the early-age concrete lining of the tunnel; Substituting the minimum safe blast center distance corresponding to the critical cumulative damage threshold obtained in step 5 and the maximum charge per segment of tunnel blasting into the Sachs formula (4) fitted in step 6, the obtained dominant blasting vibration peak velocity is the maximum safe blasting vibration peak velocity of the early-age concrete lining of the surrounding rock section of the tunnel.

2. The method for determining the blasting vibration control standard for early-age concrete lining of tunnels according to claim 1, characterized in that: The number of acoustic wave measuring points shall not be less than 5, and the distance between adjacent acoustic wave measuring points shall be 2 to 8 m.

3. The method for determining the blasting vibration control standard for early-age concrete lining of tunnels according to claim 1, characterized in that: The initial safe distance from the blast center in the blasting vibration test scheme is determined by the following formula: R0≥4D0(1) In the formula, D0 is the tunnel diameter, in meters.

4. The method for determining the blasting vibration control standard for early-age concrete lining of tunnels according to claim 1, characterized in that: The acoustic wave test adopts the single-hole acoustic wave method, and a single-transmitter dual-receiver transducer is used to conduct the test in the test hole of the acoustic wave test point. The transmission and reception are carried out in the same test hole, and water is injected into the test hole as the coupling medium of the probe transducer.

5. The method for determining the blasting vibration control standard for early-age concrete lining of tunnels according to claim 4, characterized in that: The test hole is 1.5 to 2 meters deep. During the test, a dual-transmitter transducer is placed at the bottom of the test hole, and 3 to 5 tests are performed from the bottom of the hole upwards.

6. The method for determining the blasting vibration control standard for early-age concrete lining of tunnels according to claim 1, characterized in that: A vibration measuring point is set at the location of the early-age concrete lining, 0.5 to 1 m directly above each sound wave measuring point.

7. The method for determining the blasting vibration control standard for early-age concrete lining of tunnels according to claim 1, characterized in that: The peak velocity model of the dominant blasting vibration of the early-age concrete lining in the surrounding rock section of the tunnel was fitted using the least squares method and in the form of the Sachs formula.

8. The method for determining the blasting vibration control standard for early-age concrete lining of tunnels according to claim 1, characterized in that: The minimum safe burst center distance when the maximum cumulative damage is taken as the critical cumulative damage threshold of 0.19 is solved by cubic spline interpolation method.

9. The method for determining the blasting vibration control standard for early-age concrete lining of tunnels according to claim 1, characterized in that: n≥10。

Images