A method for optimizing tunnel blasting parameters based on free surfaces

Abstract

This invention provides a method for optimizing tunnel blasting parameters based on free surfaces, comprising the following steps: S1, developing a blasting test plan based on the geological and lithological conditions of the tunnel blasting area; S2, arranging measuring points on the side of the pilot tunnel closest to the blasting of the subsequent tunnel to obtain relevant blasting parameters; S3, modifying the Sadovsky formula based on free surface conditions to calculate the relevant blasting coefficients k, α, and η; S4, comparing the peak vibration velocity measured in the blasting design plan with the allowable safe vibration velocity of the measuring points in the "Blasting Safety Regulations," back-calculating based on the safe vibration velocity threshold, and then adjusting the design parameters of the sections corresponding to peak vibration velocities that do not meet the standard; S5, repeating S3 and S4 until the vibration velocity under detonation of each section of the blasting design plan meets the safety allowable standard. This invention considers the influence of free surfaces, thus more accurately reflecting the actual situation of engineering blasting.

Description

Technical Field

[0001] This invention relates to the field of tunnel technology, and more specifically, to a method for optimizing tunnel blasting parameters incorporating free surfaces. Background Technology

[0002] Drill-and-blast method, with its advantages of fast construction speed and strong adaptability, remains one of the main construction methods in tunnel engineering. However, when tunnel construction is adjacent to buildings or structures, the resulting blasting vibrations will have adverse effects on the structure. A reasonable vibration velocity calculation method can provide a theoretical basis for on-site blasting design. In tunnel blasting, cut-holes are blasted only under single-free conditions, and the confinement effect of the surrounding rock is strong. However, when the blasting of the cut-hole provides a new free surface for subsequent blasts, the free surface increases when subsequent blast holes are detonated, and the confinement effect of the surrounding rock decreases, resulting in vibrations far less than those caused by cut-hole blasting.

[0003] Currently, the Sadovsky formula is still widely used to calculate the maximum charge per section in tunnel blasting calculations, as shown in formula (1). However, the Sadovsky formula does not consider the influence of the free surface, which leads to overly strict control of the charge in subsequent sections, which is not conducive to tunnel construction efficiency.

[0004]

[0005] Numerous studies have shown that the free surface significantly affects the blasting vibration velocity. Therefore, the existing technology has proposed a modified Sadovsky formula that takes into account the area of ​​the free surface.

[0006] The background description provided herein is for the purpose of generally presenting the context of this disclosure. Unless otherwise indicated herein, the material described in this section is not prior art to the claims of this application and should not be acknowledged as prior art by virtue of its inclusion in this section. Summary of the Invention

[0007] To address the aforementioned technical problems in related technologies, this invention proposes a method for optimizing tunnel blasting parameters based on free surfaces, comprising the following steps:

[0008] S1. Develop a blasting test plan based on the geological and lithological conditions of the tunnel blasting area;

[0009] S2. Set up measuring points on the side of the pilot tunnel close to the blasting side of the follow tunnel, record the time history curve of the blasting vibration at each measuring point, the distance from the blast center to R, and record the blasting design parameters, including the maximum Q, resistance line W, and number of free surfaces m for each section.

[0010] S3. The Sadovsky formula is modified based on the free surface condition. The modified formula is shown in formula (2). The peak vibration velocity v of each segment, the charge Q of each segment, the detonation center distance R, and the minimum resistance line W are recorded at each measuring point. minSubstituting the number of free surfaces m into formula (2), we can obtain the relevant blasting coefficients k, α, and η.

[0011]

[0012] Where v is the peak vibration velocity of each segment, cm / s; Q is the charge amount of each segment, kg; R is the distance from the detonation center, in meters; k and α are coefficients and attenuation exponents related to the terrain and geological conditions between the blast point and the protected object, respectively. min The minimum resistance line is represented by meters; m is the number of free surfaces; η is the attenuation coefficient associated with the free surfaces.

[0013] S4. Compare the peak vibration velocity measured in the blasting design scheme with the allowable safe vibration velocity of the measuring point in the "Safety Regulations for Blasting" (GB 6722-2014), and back-calculate formula (2) according to the safe vibration velocity threshold based on formula (3) to obtain the charge Q, number of free surfaces m, and distance W of the resistance line for each section. min The relationship between the three; and then, based on this relationship, the design parameters of the segment corresponding to the peak vibration velocity that does not meet the standard are adjusted;

[0014]

[0015] S5. Repeat S3 and S4 to ensure that the vibration velocity at the detonation of each section of the blasting design meets the safety allowable standard.

[0016] Specifically, in step S2, the measuring points are arranged at the same horizontal level as the blast source, and the number of measuring points arranged along the tunnel direction is no less than 3.

[0017] Specifically, the peak vibration velocity v measured in step S3 is the maximum vibration velocity value within the time delay initiation interval of the non-electrically delayed detonator.

[0018] Specifically, in step S4, the amount of propellant in each section and the spacing between boreholes are adjusted to ensure that the peak vibration velocity is less than the safety-specified allowable value.

[0019] Secondly, another embodiment of the present invention discloses a tunnel blasting parameter optimization device combining a free surface, which includes the following units:

[0020] The blasting design parameter acquisition unit acquires the time history curves of blasting vibration at each measuring point in the blasting test scheme, the blast center distance R, and records the blasting design parameters, including the charge Q, resistance line W, and number of free surfaces m for each segment.

[0021] The blasting coefficient acquisition unit is used to modify the Sadovsky formula based on the free surface condition. The modified formula is shown in formula (2). The peak vibration velocity v of each segment, the charge Q of each segment, the blast center distance R, and the minimum resistance line W are recorded at each measuring point.min Substituting the number of free surfaces m into formula (2), we can obtain the relevant blasting coefficients k, α, and η.

[0022]

[0023] Where v is the peak vibration velocity of each segment, cm / s; Q is the charge amount of each segment, kg; R is the distance from the detonation center, in meters; k and α are coefficients and attenuation exponents related to the terrain and geological conditions between the blast point and the protected object, respectively. min The minimum resistance line is represented by meters; m is the number of free surfaces; η is the attenuation coefficient associated with the free surfaces.

[0024] The blasting parameter optimization unit is used to compare the peak vibration velocity measured in the blasting design scheme with the allowable safe vibration velocity of the measuring point in the "Blasting Safety Regulations" (GB 6722-2014), and to back-calculate formula (2) according to the safe vibration velocity threshold based on formula (3) to obtain the charge Q, number of free surfaces m, and resistance line distance W for each section. min The relationship between the three; and then, based on this relationship, the design parameters of the segment corresponding to the peak vibration velocity that does not meet the standard are adjusted;

[0025]

[0026] The iterative unit, the blasting coefficient acquisition unit, and the blasting parameter optimization unit are used to repeatedly execute the blasting design scheme until the vibration velocity under detonation of each segment meets the safety allowable standard.

[0027] Specifically, the blasting design parameter acquisition unit can formulate a blasting test plan based on the geological and lithological conditions of the tunnel blasting area; and set up measuring points on the side of the pilot tunnel close to the blasting of the subsequent tunnel to record the vibration velocity value v and the distance R between the blast center and the blasting vibration at each measuring point, while also recording the blasting design parameters, including the charge Q, resistance line W, and number of free surfaces m for each section.

[0028] Specifically, in the blasting design parameter acquisition unit, the measuring points are arranged at the same horizontal height as the blast source, and the number of measuring points arranged along the tunnel direction is no less than 3.

[0029] Specifically, the peak vibration velocity v measured by the blasting coefficient acquisition unit is the maximum vibration velocity value within the delayed detonation interval of the non-electrically delayed detonator.

[0030] Specifically, the blasting parameter optimization unit adjusts the charge amount in each section and the spacing between boreholes to ensure that the peak vibration velocity is less than the safety-specified allowable value.

[0031] The tunnel blasting parameter optimization method combining free surfaces proposed in this invention has the following beneficial effects:

[0032] (1) More comprehensive consideration of factors

[0033] The tunnel blasting parameter optimization method combined with free face in this embodiment fully considers the impact of the number of free faces and the distance of the resistance line on the vibration velocity changes in the cut section and the non-cut section, and more accurately reflects the actual situation of engineering blasting.

[0034] (2) The monitoring workload is small

[0035] This blasting design scheme does not require monitoring of the entire tunnel blasting construction process. It only needs to be tested during the tunnel blasting test scheme to determine the geological and free surface influencing factors k, α, and η. After that, the charge amount for each section can be calculated back according to the modified formula. No monitoring is required for the optimized blasting scheme.

[0036] (3) It can effectively improve tunnel construction efficiency

[0037] Breaking away from the conventional Sadovsky formula that only uses the amount of explosive in the cut section as the maximum calculation, it can maximize the allocation of explosives in subsequent sections, thereby effectively improving tunnel construction efficiency.

[0038] (4) Simple to operate and highly adaptable

[0039] The arrangement of drug dosage and spacing for each segment does not require experimental verification. It can be obtained by back-calculation using the modified formula and continuously optimized. The operation is relatively simple and applicable to various geological environments, making it highly adaptable. Attached Figure Description

[0040] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0041] Figure 1 This is a flowchart of a method for optimizing tunnel blasting parameters based on a free surface, provided by an embodiment of the present invention.

[0042] Figure 2 This is the preliminary blasting design scheme provided in the embodiments of the present invention;

[0043] Figure 3 This is a schematic diagram of the measuring point arrangement provided in an embodiment of the present invention;

[0044] Figure 4 These are time history curves of various measuring points provided in the embodiments of the present invention;

[0045] Figure 5 This is a schematic diagram of a tunnel blasting parameter optimization device combined with a free surface provided in an embodiment of the present invention. Detailed Implementation

[0046] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention are within the scope of protection of the present invention.

[0047] Example 1

[0048] refer to Figure 1 This embodiment discloses a method for optimizing tunnel blasting parameters based on free surfaces, which includes the following steps:

[0049] S1. Develop a blasting test plan based on the geological and lithological conditions of the tunnel blasting area;

[0050] S2. Set up measuring points on the side of the pilot tunnel close to the blasting side of the pilot tunnel, record the time history curve of the blasting vibration at each measuring point, the distance from the blast center R, and record the blasting design parameters, including the charge Q, resistance line W, and number of free surfaces m for each section.

[0051] S3. The Sadovsky formula is modified based on the free surface condition. The modified formula is shown in formula (2). The peak vibration velocity v of each segment, the charge Q of each segment, the detonation center distance R, and the minimum resistance line W are recorded at each measuring point. min Substituting the number of free surfaces m into formula (2), we can obtain the relevant blasting coefficients k, α, and η.

[0052]

[0053] Where v is the peak velocity of the particle, cm / s; Q is the charge amount for each stage, kg; R is the distance from the detonation center, in meters; k and α are coefficients and attenuation exponents related to the terrain and geological conditions between the blast point and the protected object, respectively. min The minimum resistance line is represented by meters; m is the number of free surfaces; η is the attenuation coefficient associated with the free surfaces.

[0054] S4. Compare the peak vibration velocity measured in the blasting design scheme with the allowable safe vibration velocity of the measuring point in the "Safety Regulations for Blasting" (GB 6722-2014), and back-calculate formula (2) according to the safe vibration velocity threshold to obtain the charge Q, number of free surfaces m, and distance of the resistance line W for each section. min The relationship between the three is shown in formula (3); then the design parameters of the segment corresponding to the peak vibration velocity that does not meet the standard can be adjusted according to this relationship;

[0055]

[0056] S5. Repeat S3 and S4 to ensure that the vibration velocity at the detonation of each section of the blasting design meets the safety allowable standard.

[0057] Specifically, in step S4, the design parameters of the segment corresponding to the peak vibration velocity that does not meet the standard can be adjusted by adjusting the amount of explosive in each segment and the spacing between the boreholes to ensure that the peak vibration velocity is less than the safety-specified allowable value.

[0058] This embodiment is based on a large-section tunnel project, which is adjacent to an existing nearby tunnel with a minimum proximity distance of 17.2m. To avoid damage to the lining of the adjacent tunnel caused by tunnel blasting vibrations, the construction unit set a blasting vibration velocity threshold of 5cm / s. To better guide the blasting design, on-site tests were conducted to optimize the existing blasting scheme.

[0059] 1) Preliminary design of blasting scheme: The new tunnel will be constructed using the drill-and-blast method. The preliminary blasting design scheme is as follows: Figure 2 The blasting design parameters are shown in Table 1.

[0060] 2): Three measuring points are set up every 4m at the waist of the blasting arch near the secondary tunnel. The measuring points are numbered 1, 2, and 3 in sequence. See the measuring point layout diagram. Figure 3 Simultaneously, the vibration velocity time history curves at each measuring point were recorded using a TC4850 instrument. The time history curves at each measuring point are shown in the figure below. Figure 4 As shown in Table 2, the maximum blasting vibration v and the distance from the blast center R caused by the charge amount in each section were recorded at each measuring point. At the same time, the blasting design parameters, including the charge amount Q, resistance line W, and number of free surfaces m for each section, were also recorded. The test results are summarized in Table 2.

[0061] Table 1. Statistical table of blasting parameters in this embodiment.

[0062]

[0063] Table 2. Statistics of test results in this embodiment.

[0064]

[0065] 3): The Sadovsky formula is calculated based on the free surface condition to obtain the relevant blasting coefficients k, α, and η. Linear regression is then performed on both sides, as shown in the following formula, with regression coefficient R. 2 =0.91, indicating that the corrected formula can better reflect the actual engineering situation on site.

[0066]

[0067] 4): Compare the peak vibration velocity measured in the blasting design scheme with the allowable safe vibration velocity of the measuring point in the "Safety Regulations for Blasting" (GB 6722-2014), and back-calculate formula (4) according to the safe vibration velocity threshold to obtain the charge Q, number of free surfaces m, and distance of the resistance line W for each section. min The relationship between the three is shown in formula (5). Then, the design parameters of the segment corresponding to the peak vibration velocity that does not meet the standard can be adjusted according to this relationship.

[0068]

[0069] 5) Repeat steps 3) and 4) until the vibration velocity of each section of the blasting design meets the safety allowable standard.

[0070] Compared with existing technologies, the tunnel blasting parameter optimization method combining free surfaces proposed in this embodiment has the following advantages:

[0071] (1) More comprehensive consideration of factors

[0072] The tunnel blasting parameter optimization method combined with free faces in this embodiment fully considers the impact of the number of free faces and the distance between the resistance lines on the vibration velocity changes in the cut-out and non-cut-out sections, thus more accurately reflecting the actual situation of engineering blasting.

[0073] (2) The monitoring workload is small

[0074] This blasting design scheme does not require monitoring of the entire tunnel blasting construction process. It only needs to be tested during the tunnel blasting test scheme to determine the geological and free surface influencing factors k, α, and η. After that, the charge amount for each section can be calculated back according to the modified formula. No monitoring is required for the optimized blasting scheme.

[0075] (3) It can effectively improve tunnel construction efficiency

[0076] Breaking away from the conventional Sadovsky formula that only uses the amount of explosive in the cut section as the maximum calculation, it can maximize the allocation of explosives in subsequent sections, thereby effectively improving tunnel construction efficiency.

[0077] (4) Simple to operate and highly adaptable

[0078] The arrangement of drug dosage and spacing for each segment does not require experimental verification. It can be obtained by back-calculation using the modified formula and continuously optimized. The operation is relatively simple and applicable to various geological environments, making it highly adaptable.

[0079] Example 2

[0080] refer to Figure 5 This embodiment provides a tunnel blasting parameter optimization device that combines free surfaces, which includes the following units:

[0081] The blasting design parameter acquisition unit acquires the time history curves of blasting vibration at each measuring point in the blasting test scheme, the blast center distance R, and records the blasting design parameters, including the charge Q, resistance line W, and number of free surfaces m for each segment.

[0082] Specifically, the blasting design parameter acquisition unit can formulate a blasting test plan based on the geological and lithological conditions of the tunnel blasting area; and set up measuring points on the side of the pilot tunnel close to the blasting of the subsequent tunnel to record the vibration velocity value v and the distance from the blast center R of the blasting vibration at each measuring point, while also recording the blasting design parameters, including the charge Q, resistance line W, and number of free surfaces m for each section.

[0083] The blasting coefficient acquisition unit is used to modify the Sadovsky formula based on the free surface condition. The modified formula is shown in formula (2). The peak vibration velocity v of each segment, the charge Q of each segment, the blast center distance R, and the minimum resistance line W are recorded at each measuring point. min Substituting the number of free surfaces m into formula (2), we can obtain the relevant blasting coefficients k, α, and η.

[0084]

[0085] Where v is the peak vibration velocity of each segment, cm / s; Q is the charge amount of each segment, kg; R is the distance from the detonation center, in meters; k and α are coefficients and attenuation exponents related to the terrain and geological conditions between the blast point and the protected object, respectively. min The minimum resistance line is represented by meters; m is the number of free surfaces; η is the attenuation coefficient associated with the free surfaces.

[0086] The blasting parameter optimization unit is used to compare the peak vibration velocity measured in the blasting design scheme with the allowable safe vibration velocity of the measuring point in the "Safety Regulations for Blasting" (GB 6722-2014), and to back-calculate formula (2) based on the safe vibration velocity threshold to obtain the charge Q, number of free surfaces m, and resistance line distance W for each section. min The relationship between the three is shown in formula (3); then the design parameters of the segment corresponding to the peak vibration velocity that does not meet the standard can be adjusted according to this relationship;

[0087]

[0088] The iterative unit, the blasting coefficient acquisition unit, and the blasting parameter optimization unit are used to repeatedly execute the blasting design scheme until the vibration velocity under detonation of each segment meets the safety allowable standard.

[0089] Specifically, in the blasting parameter optimization unit, the design parameters of the sections corresponding to the peak vibration velocities that do not meet the standard can be adjusted by adjusting the charge amount and the spacing between the boreholes in each section to ensure that the peak vibration velocity is less than the safety-specified allowable value.

[0090] Compared with existing technologies, the tunnel blasting parameter optimization method combining free surfaces proposed in this embodiment has the following advantages:

[0091] (1) More comprehensive consideration of factors

[0092] The tunnel blasting parameter optimization method combined with free faces in this embodiment fully considers the impact of the number of free faces and the distance between the resistance lines on the vibration velocity changes in the cut-out and non-cut-out sections, thus more accurately reflecting the actual situation of engineering blasting.

[0093] (2) The monitoring workload is small

[0094] This blasting design scheme does not require monitoring of the entire tunnel blasting construction process. It only needs to be tested during the tunnel blasting test scheme to determine the geological and free surface influencing factors k, α, and η. After that, the charge amount for each section can be calculated back according to the modified formula. No monitoring is required for the optimized blasting scheme.

[0095] (3) It can effectively improve tunnel construction efficiency

[0096] Breaking away from the conventional Sadovsky formula that only uses the amount of explosive in the cut section as the maximum calculation, it can maximize the allocation of explosives in subsequent sections, thereby effectively improving tunnel construction efficiency.

[0097] (4) Simple to operate and highly adaptable

[0098] The arrangement of drug dosage and spacing for each segment does not require experimental verification. It can be obtained by back-calculation using the modified formula and continuously optimized. The operation is relatively simple and applicable to various geological environments, making it highly adaptable.

[0099] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for optimizing tunnel blasting parameters with free face coupling, characterized in that, It comprises the following steps: S1, according to the geological conditions and lithological conditions of the tunnel blast area, make a blasting test scheme; S2, arrange measuring points on the side of the preceding hole close to the blasting side of the following hole, record the time history curve of each measuring point blasting vibration, and record the blast center distance R, and the blasting design parameters, including the segment-specific charge Q, the resistance line W, and the number of free surfaces m; S3, the Sadaovski formula is modified based on the free surface condition, the modified formula is shown in formula (2), the peak vibration velocity v, the charge Q, the distance from the explosion center R, the minimum resistance line W of each measuring point record are substituted into formula (2) to calculate the related blasting coefficient k, α and η value: min , the free surface number m is substituted into formula (2) to calculate the related blasting coefficient k, α and η value: Wherein, v is the peak vibration velocity of each section, cm / s; Q is the dosage of each section, kg; R is the distance from the explosion center, unit: meter; k and a are the coefficient and attenuation index related to the topography and geological conditions between the blasting point and the protected object, W min is the minimum resistance line, unit: meter; m is the number of free surfaces; η is the attenuation coefficient related to the free surface; S4, according to the safety vibration velocity threshold, the formula (2) is inversely calculated according to the peak vibration velocity measured in the blasting design scheme and the safety vibration velocity allowed in the Blasting Safety Regulations (GB 6722-2014), to obtain the segment-specific charge Q, the free surface number m, and the distance W of the resistance line min the relationship among the three; then, according to the relationship, the segment-specific design parameters corresponding to the peak vibration velocity that does not meet the standard are adjusted; S5, repeat S3 and S4 to ensure that the vibration speed under the blasting design scheme of each segment is less than the safety allowable value.

2. The method of claim 1, wherein: The measuring points in step S2 are arranged at the same horizontal height as the blast source, and the number of measuring points arranged along the tunnel trend is not less than 3.

3. The method of claim 1, wherein, The peak vibration velocity v measured in step S3 is the maximum vibration velocity value within the delay blasting interval of non-electric delay detonator.

4. The method of claim 1, wherein, In step S4, by adjusting the segment-specific charge and the blast hole row spacing, the peak vibration velocity is ensured to be less than the safety allowable value.

5. A device for optimizing parameters of tunnel blasting with free face, characterized in that, It comprises the following units: The blasting design parameter acquisition unit acquires the time history curve of each measuring point blasting vibration in the blasting test scheme, the blast center distance R, and records the blasting design parameters, including the segment-specific charge Q, the resistance line W, and the number of free surfaces m; The blasting coefficient acquisition unit is used for calculating the Sadaovsky formula based on the free surface condition, and the correction formula is shown in formula (2). The peak vibration velocity v, the explosive quantity Q, the distance from the explosion center R, and the minimum resistance line W of each section recorded by each measuring point are substituted into formula (2) to obtain the related blasting coefficients k, α, and η values: min , the number of free surfaces m is substituted into formula (2) to obtain the related blasting coefficients k, α, and η values: Wherein, v is the peak vibration velocity of each section, cm / s; Q is the dosage of each section, kg; R is the distance from the explosion center, unit: meter; k and a are the coefficient and attenuation index related to the topography and geological conditions between the blasting point and the protected object, W min is the minimum resistance line, unit: meter; m is the number of free surfaces; η is the attenuation coefficient related to the free surface; The blasting parameter optimization unit is used for comparing the measured peak vibration velocity in the blasting design scheme with the allowed safety vibration velocity of the measuring point in the Blasting Safety Regulations (GB 6722-2014), referring to formula (3), inversely calculating formula (2) according to the safety vibration velocity threshold, and obtaining the section-specific charge Q, the free surface number m and the distance W of the resistance line min The relationship among the three; then according to the relationship, the section-specific design parameters corresponding to the peak vibration velocity not meeting the standard are adjusted; The iteration unit is used to repeatedly execute the blasting coefficient acquisition unit and the blasting parameter optimization unit to ensure that the vibration speed under the blasting design scheme of each segment meets the safety allowable standard.

6. The apparatus of claim 5, wherein, The blasting design parameter acquisition unit can make a blasting test scheme according to the geological conditions and lithological conditions of the tunnel blast area, and arrange measuring points on the side of the preceding hole close to the blasting side of the following hole, record the vibration velocity v of each measuring point blasting vibration, and record the blast center distance R, and the blasting design parameters, including the segment-specific maximum charge Q, the resistance line W, and the number of free surfaces m.

7. The apparatus of claim 6, wherein: The measuring points in the blasting design parameter acquisition unit are arranged at the same horizontal height as the blast source, and the number of measuring points arranged along the tunnel trend is not less than 3.

8. The apparatus of claim 6, wherein, The peak vibration velocity v measured by the blasting coefficient acquisition unit is the maximum vibration velocity value within the delay blasting interval of non-electric delay detonator.

9. The apparatus of claim 5, wherein, In the blasting parameter optimization unit, by adjusting the segment-specific charge and the blast hole row spacing, the peak vibration velocity is ensured to be less than the safety allowable value.

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