Method for determining the charge quantity of a single hole in water-interval charge hole-by-hole blasting under micro-vibration control conditions

Abstract

A method for determining the charge amount of a single hole for hole-by-hole blasting with water-interval charge under micro-vibration control conditions, comprising: 1. determining explosive and blasthole parameters; 2. determining an initial single-hole charge amount; 3. calculating the maximum initial stress of the blasthole wall; 4. determining the blasting action time of rock mass particles at a protected object; 5. determining the speed response and maximum vibration velocity of the rock mass particles at the protected object; 6. determining the speed response main frequency and safe vibration velocity of the rock mass particles at the protected object during the entire vibration stage; 7. determining the optimized final single-hole charge amount. The present invention can ensure the safety of the vibration effect of surrounding protected buildings and realize the single-hole charge amount of hole-by-hole blasting with water-interval charge under micro-vibration control conditions with high-efficiency construction, fully utilizing the energy of explosives, saving construction costs, and improving the blasting and rock-breaking effect.

Description

Technical Field

[0001] The invention relates to the field of urban rock mass blasting construction, in particular to a method for determining the charge amount of a single hole in water-interval charging hole-by-hole blasting under micro-vibration control conditions. Background Art

[0002] Blasting technology is an economical and effective construction method for rock excavation. However, with the increasing complexity of the operation and surrounding environment, the precision requirements for blasting technology are getting higher and higher. When blasting and excavating rock in cities, especially in downtown areas with many buildings (structures), if the blasting design is slightly inappropriate, the blasting seismic wave will cause the surrounding buildings (structures) to produce a more prominent blasting vibration effect problem, causing damage to or even collapse of the buildings (structures), seriously threatening the safety of people's lives and property. In order to effectively control the hazards of rock blasting vibration effects under complex urban environmental conditions, hole-by-hole blasting technology is generally used instead of traditional row-by-row micro-difference blasting technology. The hole-by-hole blasting technology adopts a single blasthole delay method. Each blasthole is detonated separately in space and time according to a specific detonation sequence. The first blasting blasthole creates more free surfaces for the subsequent blasting blastholes, thereby achieving the purpose of reducing blasting vibration and improving blasting effect. Due to the strict requirements for blasting vibration, for the sake of safety, the hole-by-hole blasting strictly controls the (maximum) single-hole charge and total charge of each blasting, resulting in slow progress and low efficiency in blasting construction. In hole-by-hole blasting projects, the Sadovsky formula is generally used to determine the safe allowable distance of blasting vibration from the amount of explosives to achieve safe vibration-controlled blasting. However, in blasting projects under complex urban environmental conditions, the distance between the blasting source and the surrounding buildings (structures) is often fixed and small, which is highly dangerous. How to efficiently carry out hole-by-hole blasting construction under the condition of effectively controlling the safety of surrounding protected buildings (structures) is an urgent problem to be solved in the field of urban rock blasting construction.

[0003] The water-interval charge structure is a vibration-controlled, efficient, energy-saving and environmentally friendly blasting charge structure. Under the current background of low-carbon, ecological and green development, the axial water-interval radial water-uncoupled charge structure combined with hole-by-hole detonation technology has been more and more widely used in urban rock excavation projects in recent years. Common axial water-interval charge structures include upper water interval, lower water interval and two-end water interval. After comprehensive comparison of the vibration control, surrounding rock protection, energy utilization, blasting effect and dust reduction evaluation indicators of the three axial water-interval charge structures, the two-end water-interval charge structure is the best, so it is the most widely used. Common radial uncoupled charge structures include radial soil uncoupled, radial air uncoupled and radial water uncoupled. After comprehensive comparison of the blasting effect, energy utilization, maximum initial stress, blasting action time, dust reduction and noise evaluation indicators of the three radial uncoupled charge structures, the radial water-uncoupled charge structure is the best and its application is also quite extensive.

[0004] Combining the advantages of water-interval at both ends and radial water-uncoupled charge structure and hole-by-hole blasting, the hole-by-hole blasting technology of radial water-uncoupled charge structure at both ends (referred to as water-interval charge hole-by-hole blasting) is used for urban rock excavation projects as the optimal charge structure. Although the vibration intensity caused by water-interval charge hole-by-hole blasting is lower than that of other charge structures, it is used in urban rock excavation projects under sensitive environments, and the vibration control requirements are higher. If the main blasting parameters, especially the single-hole charge, are selected too large, the blasting vibration effect hazards caused will lead to various engineering safety accidents and civil disputes. If the single-hole charge is selected too small, it will delay the project progress and increase the project cost. At present, the single-hole charge of water-interval charge hole-by-hole blasting is determined by considering energy utilization and blasting effect, and the control of blasting vibration effect is less considered, and the specific blasting vibration safety standards of the protected buildings (structures) in the blasting area are not considered. Therefore, how to determine the single-hole charge in water-interval charge hole-by-hole blasting is the key to ensure the safe and efficient construction of urban rock blasting excavation projects. Summary of the invention

[0005] The present invention solves the shortcomings of the prior art and provides a method for determining the amount of single-hole explosives for water-interval charging hole-by-hole blasting under micro-vibration control conditions, which can ensure the safety of the vibration effect of surrounding protected buildings and achieve high-efficiency construction.

[0006] To achieve the above object, the present invention proposes a method for determining the charge amount of a single hole in water-interval charge hole-by-hole blasting under micro-vibration control conditions, comprising the following steps:

[0007] Step 1: Determine the explosive and blasthole parameters:

[0008] Select the type of explosive for hole-by-hole blasting according to the properties of the blasted rock mass, and obtain the following parameters of the selected explosive: Explosive density ρ e ; Explosive unit consumption q;

[0009] Determine the step height H according to the project site conditions and calculate the resistance line w d Height:

[0010] w d =(0.6~0.9)H (1)

[0011] The diameter d of a single blasthole is determined based on the step height and the diameter of the drill rig used. b , and determine the hole spacing c and row spacing d at the same time:

[0012] c=ew d (2)

[0013] d=(0.9~0.95)w d (3)

[0014] Where, e is the proximity coefficient, e = 1.0 ~ 1.4;

[0015] Extra deep length h c Determined by the following formula:

[0016] h c =(0.15~0.35)w d (4)

[0017] Blockage length h d Determined by the following formula:

[0018] h d =(0.63~0.88)w d (5)

[0019] The total length of the blasthole L is the step height H and the extra-deep length h c sum;

[0020] The blasthole adopts radial water-uncoupled charge, and the radial water-uncoupled coefficient k is set d 1.2~2;

[0021] Charge diameter d c Determined by the following formula:

[0022] d c =d b k d (7)

[0023] Step 2: Determine the initial single-hole dosage:

[0024] The single hole dosage Q is calculated by volume method a :

[0025] Q a =qcXH (8) In the formula: X = w when calculating the amount of medicine in the front row holes d , when calculating the dosage of the rear row holes, X = d;

[0026] According to the type of building / structure protected in the explosion zone, a vibration main frequency f0 is assumed, and the safe allowable vibration velocity value v0 is determined by the vibration main frequency f0;

[0027] According to v0 and Sadovsky's empirical formula, the single-hole charge Q under the vibration safety condition of the protected object is calculated. b ;

[0028]

[0029] In the formula: r is the distance from the explosion center, that is, the distance from the protected building / structure to the explosion source; K is the site coefficient, and β is the attenuation coefficient;

[0030] Get Q a and Qb The smaller value of the two is taken as the initial single-hole dosage Q0;

[0031] Step 3: Calculate the maximum initial stress of the blasthole wall:

[0032] Determine the charge length l of the blast hole according to the initial single-hole charge Q0 c :

[0033]

[0034] The blasthole adopts a two-end water interval charging structure, the upper and lower water interval lengths are equal, and the length of each end water interval is l w Determined by the following formula:

[0035]

[0036] The Starfield superposition method is used to calculate the maximum initial stress P of the blasthole wall. r,t ;

[0037] Step 4: Determine the blasting time of the rock mass points at the protected object;

[0038] The hole wall transmission stress generated by the explosion of the explosive decays with the increase of the propagation distance in the surrounding rock medium. The stress wave pressure rise time t s It is found by the following formula:

[0039]

[0040] Where: Damping coefficient As the distance from the center of the explosion changes, the coefficients η1, η2, ∈1, and ∈2 are determined based on the full-scale tests of Atchison and Tournay; It is a coefficient related to the rock longitudinal wave velocity and the blasthole radius.

[0041] Stress at t j The stress wave peak value is taken as the relative infinitesimal value of stress, and the duration is t j According to Newton's iteration method, we can get:

[0042]

[0043] Where: j is the number of iterations, and the starting calculation time is t0 = (8-10) × t s , after j iterations, the blasting time t is obtained j .

[0044] Step 5: Determine the velocity response and maximum vibration velocity of the rock mass point vibration at the protected object;

[0045] Analyze the radial displacement and radial velocity of the rock per unit volume at the protected object.

[0046] The rock mass point is between 0 and t j Forced vibration occurs in the time period, and the displacement response u of the single-degree-of-freedom rock mass system in the forced vibration stage is determined by structural dynamics r (t):

[0047]

[0048] Where: Z is the time lag function f(t) = Z(e -at -e -bt ), M is the mass of rock per unit volume at the protected object; ω is the circular frequency of the rock; δ is the distance attenuation coefficient of the stress wave; r b is the radius of the blast hole, r b =d b / 2;

[0049] The radial velocity and displacement of the rock mass are derivative relations. The forced vibration velocity response v is determined according to formula (16): r (t):

[0050]

[0051] At time t>t j After that, the rock particles vibrate freely, and equations (16) and (17) are j The displacement at time u r (t j ) and speed v r (t j ) as the initial condition of free vibration, and the free vibration velocity response ν is obtained according to structural dynamics f (t):

[0052]

[0053] Where: ζ is the damping ratio; ω d is the damping frequency,

[0054] The velocity response of the entire stage is v(t)=v r (t)+ν f (t), draw the speed response curve of the whole stage, and find the maximum speed response v 1max ;

[0055] Step 6: Determine the velocity response main frequency and safe vibration speed of the rock mass points where the protected building / structure is located during the entire vibration stage:

[0056] According to the velocity response curve in step 5, the rock vibration velocity response curve at the protected building / structure object is subjected to fast Fourier transform to obtain the actual vibration main frequency f1 of the velocity response; and a new safe vibration velocity v1 is determined according to the vibration main frequency f1;

[0057] Step 7: Determine the final single-hole dosage after optimization:

[0058] The actual vibration main frequency f1 and safe vibration speed v1 obtained in step 6 are used to replace the assumed vibration main frequency f0 and safe vibration speed v0 in step 2, and v1 is compared with the velocity response peak value v obtained in step 5. 1max Compare:

[0059] If v 1max Less than v1, increase the dosage ΔQ based on the initial single-hole dosage Q0;

[0060] If v 1max If it is greater than v1, the dosage ΔQ is reduced based on the initial single-hole dosage Q0;

[0061] Finally, the actual drug dosage Q1 = Q0 ± ΔQ is obtained, and the actual Q1 is used to replace Q0 in step 2. The first cycle calculation is completed.

[0062] Use the actual blast hole charge Q1 to start the second cycle calculation and repeat steps 3 to 7 until k cycles have passed and the safe vibration velocity v is obtained. k Equal to the velocity response peak value v kmax When the actual drug amount Q in the k-1th cycle calculation is selected k-1 Determine the final dosage, that is, the final single-hole dosage is Q k-1 =Q0±(k-1)×ΔQ.

[0063] In this embodiment, in step 1, the ultra-deep length h c When determining: When the rock is hard rock: h c =0.35w d , when the rock is soft, select h c =0.15w d .

[0064] In this embodiment, in step 1, the radial water uncoupling coefficient k is determined according to the wave impedance matching relationship between the water medium and the rock. d ;

[0065]

[0066] Where: η is the energy utilization rate, ρ r is the rock density, c p is the longitudinal wave velocity of the shock wave when it propagates in the rock, ρw is the density of water, k w is the compression modulus of water; ρ e is the density of explosive; D is the detonation velocity of explosive.

[0067] In this implementation, in step 2, the vibration main frequency f0 and the safe allowable vibration velocity value v0 are determined according to the "Explosive Safety Regulations".

[0068] In this embodiment, in step 3, the Starfield superposition method is used to calculate the specific maximum incident stress P r,i The formula is as follows:

[0069]

[0070] Where: [*] represents the largest positive integer not greater than *; l c is the actual charge length; is the equivalent spherical package diameter, W s W is the actual explosive specific detonation heat; t is the specific explosion heat of TNT explosive; α is the attenuation coefficient of the peak value of shock wave stress propagating along the axial direction of the blast hole; B is the parameter of the JWL state equation; The amount of medicine in the final medicine package; is the diameter of the terminal drug package;

[0071] Considering the influence of radial water uncoupling on stress: the water between the charge and the hole wall is the medium for stress wave to enter the hole wall. According to the continuous medium condition, the maximum transmission stress P of the shock wave generated in the blasthole is r,t Also called the maximum initial stress of the blasthole wall is determined by the following formula:

[0072]

[0073] Where: A and ψ are constants obtained from Baum's experiment;

[0074] The maximum initial stress P of the blast hole wall is obtained by formula (13): r,t .

[0075] In this embodiment, in step six, the vibration main frequency f1 and the safe allowable vibration velocity value v1 are determined according to the "Explosive Safety Regulations".

[0076] In this embodiment, ΔQ is 1% to 11% of the initial single-hole drug volume Q0.

[0077] In this embodiment, at the end of step seven, the optimized blast hole charge Q k-1 Substitute the initial single-hole charge Q0 into formula 10 and formula 11 to determine the optimized charge length l c Length of water interval l w .

[0078] Compared with the prior art, the present invention has the following beneficial effects:

[0079] 1. This method not only strictly complies with the current blasting safety regulations and ensures the safety of the vibration effect of the protected buildings / structures, but also maximizes the optimization of the single-hole charge while meeting the micro-vibration control target, thereby improving the construction efficiency of urban rock excavation projects.

[0080] 2. The axial and radial water medium in the blasthole can significantly reduce the excessive crushing of the rock mass near the hole wall and the damage to the rock mass at the bottom of the hole by reducing the peak value of the hole wall stress. At the same time, by increasing the action time of the hole wall stress, it can significantly increase the rock crushing range and uniformize the blasting fragmentation, thereby making full use of the explosive energy, saving construction costs, and improving the blasting rock breaking effect.

[0081] 3. By adopting the blasting method of radial water-uncoupled charging with water intervals at both ends, the impact of dust and noise on the surrounding environment is reduced, and at the same time, environmentally friendly and ecological blasting construction is achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0082] Figure 1 It is a schematic diagram of the process of the present invention.

[0083] Figure 2 It is the displacement and velocity response curve of the object to be protected of the present invention. DETAILED DESCRIPTION

[0084] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0085] In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the fact that ordinary technicians in the field can implement it. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0086] See also Figure 1 , a method for determining the amount of charge in a single hole of water-interval charge blasting hole by hole under micro-vibration control conditions, comprising the following steps:

[0087] Step 1: Determine the explosive and blasthole parameters:

[0088] According to the properties of the blasted rock mass, the appropriate type of explosive for hole-by-hole blasting is selected, and the following parameters of the selected explosive are obtained: Explosive density ρ e ; Explosive unit consumption q;

[0089] Determine the step height H according to the project site conditions and calculate the resistance line w d Height:

[0090] w d =(0.6~0.9)H (1)

[0091] The diameter d of a single blasthole is determined based on the step height and the diameter of the drill rig used. b , hole spacing c and row spacing d:

[0092] c=ew d (2)

[0093] d=(0.9~0.95)w d (3)

[0094] In the formula, e is the proximity coefficient, which is generally taken as e = 1.0 ~ 1.4;

[0095] Extra deep length h c Determined by the following formula:

[0096] h c =(0.15~0.35)w d (4)

[0097] When the rock is hard, choose a slightly larger super-depth value; when the rock is soft, choose a slightly smaller super-depth value;

[0098] Blockage length h d Determined by the following formula:

[0099] h d =(0.63~0.88)w d (5)

[0100] The total length of the blasthole L is the step height H and the extra-deep length h c sum;

[0101] The blasthole adopts radial water-uncoupled charge, and a suitable radial water-uncoupled coefficient k is determined according to the matching relationship between the water medium and the rock wave impedance. d As the energy utilization rate η increases, the radial water decoupling coefficient decreases. According to practical experience, when k d >2, the shock wave stress generated by the fine grain column in the blast hole is too small; when k d When k <1.2, the radial water volume in the borehole is too small to promote the "water wedge" effect; when k dWhen the energy utilization rate is between 1.2 and 2, the energy utilization rate changes little and basically remains at 46% to 52%. Considering that the energy utilization rate can be relatively large and at the same time there is enough water in the charge section to produce the "water wedge" effect, a suitable value of the energy utilization rate of explosive blasting is determined, and the radial water uncoupling coefficient k d It is further determined by the following formula;

[0102]

[0103] Where: η is the energy utilization rate,

[0104] ρ r is the rock density, c p is the longitudinal wave velocity of the shock wave when it propagates in the rock, ρ w is the density of water, k w is the compression modulus of water; ρ e is the density of explosives; D is the detonation velocity of explosives;

[0105] Charge diameter d c Determined by the following formula:

[0106] d c =d b k d (7)

[0107] Step 2: Determine the initial single-hole dosage:

[0108] The single hole dosage Q is calculated by volume method a :

[0109] Q a =qcXH (8)

[0110] In the formula: X = w when calculating the amount of medicine for the front row holes d , when calculating the dosage of the rear row holes, X = d;

[0111] According to the type of building / structure protected in the blasting area, a vibration main frequency f0 is preliminarily assumed to determine the safe allowable vibration velocity value v0. The vibration main frequency f0 and the safe allowable vibration velocity value v0 are determined in accordance with the safe allowable standards for blasting vibration in the "Safety Regulations for Blasting" (GB / 6722-2014);

[0112] According to v0 and Sadovsky's empirical formula, the single-hole charge Q under the vibration safety condition of the protected object is calculated. b ;

[0113]

[0114] Where: r is the distance from the explosion center, that is, the distance from the protected building / structure to the explosion source; the site coefficient K and the attenuation coefficient β are coefficients related to the topography and geological conditions of the explosion area, which can be determined based on the empirical values ​​of similar engineering sites, and if necessary, can also be determined by conducting on-site blasting tests;

[0115] Get Q a and Q b The smaller value of the two is taken as the initial single-hole dosage Q0;

[0116] Step 3: Calculate the maximum initial stress of the blasthole wall:

[0117] Determine the charge length l of the blast hole according to the initial single-hole charge Q0 c :

[0118]

[0119] The blasthole adopts a two-end water interval charging structure, the upper and lower water interval lengths are equal, and the length of each end water interval is l w Determined by the following formula:

[0120]

[0121] For the entire blasthole, the length distribution of each section from top to bottom is: d + Upper water interval l w +Charging section l c +Lower water interval l w ;

[0122] According to the length of the blasthole, the columnar charge in the blasthole is divided into multiple spherical charges of equal volume. The diameter of the spherical charge is set to ensure that the charge amount of all spherical charges is the same as that of the columnar charge. The radial water-uncoupled charge structure at both ends is a small-caliber shallow hole micro-vibration blasting. The attenuation of the blasting stress along the axial direction of the blasthole with time is ignored, and the position of the detonation point is ignored. All spherical charges are set to be detonated at the same time. The superposition of the shock wave stress generated by the spherical charge at any position in the axial direction of the blasthole can obtain the stress at that position. The maximum value of the shock wave stress occurs at the center of the charge length. Since the stress at the center of the charge length has the greatest impact on the adjacent buildings, the stress at the center of the charge length here is the maximum initial stress of the blasthole wall.

[0123] Considering the influence of the axial length of the charge column on the stress, the calculation is simplified. Here, the stress superposition generated by the half-segment cylindrical charge at the center of the charge section is calculated. Assume that the number of spherical charges equivalent to the half-segment cylindrical charge is N, and the diameters of the first N-1 spherical charges are exactly the same. The remaining charge after deducting the charge of the first N-1 spherical charges from the charge of the half-segment cylindrical charge is used to determine the diameter of the terminal spherical charge. Finally, the stress generated by the explosion of the two half-segment cylindrical charges at the center is superimposed, which is the maximum incident stress P of the shock wave at the center of the charge section at the hole wall. r,i :

[0124]

[0125] Where: [*] represents the largest positive integer not greater than *; l c is the actual charge length, d c is the actual charge diameter; is the equivalent spherical package diameter, W s W is the actual explosive specific detonation heat; t is the specific explosion heat of TNT explosive; α is the attenuation coefficient of the peak value of shock wave stress propagating along the axial direction of the blast hole; B is the parameter of the JWL state equation; The amount of medicine in the final medicine package; is the diameter of the terminal drug package;

[0126] Considering the influence of radial water uncoupling on stress: the water between the charge and the hole wall is the medium for stress wave to enter the hole wall. According to the continuous medium condition, the maximum transmission stress P of the shock wave generated in the blasthole is r,t Also called the maximum initial stress of the blasthole wall is determined by the following formula:

[0127]

[0128] Where: A and ψ are constants obtained from Baum's experiment;

[0129] The maximum initial stress P of the blast hole wall is obtained by formula (13): r,t ;

[0130] Step 4: Determine the blasting time of the rock mass points at the protected object;

[0131] The hole wall transmission stress generated by the explosion of the explosive decays with the increase of the propagation distance in the surrounding rock medium. The stress wave pressure rise time t s It is found by the following formula:

[0132]

[0133] Where: Damping coefficient As the distance from the center of the explosion changes, the coefficients η1, η2, ∈1, and ∈2 are determined based on the full-scale tests of Atchison and Tournay; It is a coefficient related to the rock longitudinal wave velocity and the blasthole radius.

[0134] Stress at t k The stress wave peak value is taken as the relative infinitesimal value of stress, and the duration is t j According to Newton's iteration method, we can get:

[0135]

[0136] Where: j is the number of iterations, and the starting calculation time is t0 = (8-10) × t s , after j iterations, the blasting time t is obtained j .

[0137] Step 5: Determine the velocity response and maximum vibration velocity of the rock mass point vibration at the protected object;

[0138] Analyze the radial displacement and radial velocity of the rock per unit volume at the protected object.

[0139] The rock mass particles are between 0 and t j Forced vibration occurs in the time period, and the displacement response u of the single-degree-of-freedom rock mass system in the forced vibration stage is determined by structural dynamics r (t):

[0140]

[0141]

[0142] Where: Z is the time lag function f(t) = Z(e -at -e -bt ), M is the mass of rock per unit volume at the protected object; ω is the circular frequency of the rock; δ is the distance attenuation coefficient of the stress wave; r b is the radius of the blast hole, r b =d b / 2;

[0143] The radial velocity and displacement of the rock mass are derivative relations. The forced vibration velocity response v is determined according to formula (16): r (t):

[0144]

[0145] At time t>t j After that, the rock particles vibrate freely, and equations (16) and (17) are jThe displacement at time u r (t j ) and speed v r (t j ) as the initial condition of free vibration, and the free vibration velocity response v is obtained according to structural dynamics f (t):

[0146]

[0147] Where: ζ is the damping ratio; ω d is the damping frequency,

[0148] The velocity response of the entire stage is v(t)=v r (t)+v f (t), draw the speed response curve of the whole stage, and find the maximum value v of the speed response (curve) 1max ;

[0149] Step 6: Determine the velocity response main frequency and safe vibration speed of the rock mass points where the protected building / structure is located during the entire vibration stage;

[0150] According to the velocity response curve in step 5, the rock vibration velocity response curve at the protected building / structure object is subjected to fast Fourier transform to obtain the actual vibration main frequency f1 of the velocity response; referring to the blasting vibration safety allowable standard of the "Safety Regulations for Blasting" (GB / 6722-2014), a new safe vibration speed v1 is determined according to the vibration main frequency f1;

[0151] Step 7: Determine the final single-hole dosage after optimization:

[0152] The actual vibration main frequency f1 and safe vibration speed v1 obtained in step 6 are used to replace the assumed vibration main frequency f0 and safe vibration speed v0 in step 2, and v1 is compared with the velocity response peak value v obtained in step 5. 1max Compare:

[0153] If v 1max Less than v1, increase the dosage ΔQ based on the initial single-hole dosage Q0;

[0154] If v 1max If it is greater than v1, the dosage ΔQ is reduced based on the initial single-hole dosage Q0;

[0155] ΔQ is generally taken as 1% to 11% of the initial single hole dose Q0

[0156] Finally, the actual drug dosage Q1 = Q0 ± ΔQ is obtained, and the actual Q1 is used to replace Q0 in step 2. The first cycle calculation is completed.

[0157] Use the actual blast hole charge Q1 to start the second cycle calculation and repeat steps 3 to 7 until k cycles have passed and the safe vibration velocity v is obtained. k Equal to the velocity response peak value v kmax When the actual drug amount Q in the k-1th cycle calculation is selected k-1 Determine the final dosage, that is, the final single-hole dosage is Q k-1 =Q0±(k-1)×ΔQ;

[0158] The optimized blast hole charge Q k-1 Substitute the initial single-hole charge Q0 into formula 10 and formula 11 to determine the optimized charge length l c,k-1 Length of water interval l w,k-1 .

[0159] The relationship between the protected object, the main vibration frequency f, and the safe allowable vibration speed v in the "Blasting Safety Regulations" is as follows:

[0160]

[0161] Example:

[0162] Step 1: Determine the explosive and blasthole parameters.

[0163] In a city (foundation pit) rock excavation project under complex environmental conditions, water-interval charging shallow hole step-by-step blasting technology is used. Emulsion explosives are selected according to the rock properties on site. The parameters of the explosives are as follows: Explosive density ρ e =1000kg / m 3 Explosive consumption per unit q = 0.3 kg / m 3 ; Explosion speed D = 3500m / s.

[0164] Select the YT-27 pneumatic rock drill and the cross-shaped alloy drill bit for drilling. According to the diameter of the drill, the diameter of a single blasthole is determined as d. b =0.08m.

[0165] According to the project site conditions and engineering experience, the step height H = 1.6m is determined, and the resistance line w is determined by formula (1): d =1.3m. The hole spacing c = 1.6m and row spacing d = 1.2m are determined by equations (2) and (3); the super depth h is determined by equations (4) and (5). c =0.31m, blocking length h d =0.8m, total length of blasthole L=1.91m.

[0166] Determine the radial water decoupling coefficient k based on the wave impedance matching relationship between water medium and rock d , the parameter ρ r =2580kg / m 3、c p =4000m / s,ρ w =1000kg / m 3 , k w = 2100MPa Substitute into formula (6) to determine the radial water uncoupling coefficient k d Relationship with energy utilization rate η.

[0167] As the energy utilization rate η increases, the borehole radial water decoupling coefficient k d To ensure a high energy utilization rate and sufficient water volume in the charge section to trigger the "water wedge" effect, the energy utilization rate η = 46.48% is selected. Substituting the determined η = 46.48% into formula (6), the radial water uncoupling coefficient k is determined. d =2.0, and then determine d through formula (7) c =0.04m.

[0168] Step 2: Determine the initial single-hole dosage.

[0169] The volume method is used to calculate the dosage of a single hole, and the relevant parameters are substituted into formula (8) to obtain Q a =0.92kg.

[0170] The protected object in the blasting area is a multi-story brick building, which is 20 meters away from the blast source, that is, the distance from the explosion center is r = 20 meters. Referring to the blasting vibration safety allowable standard of the current "Safety Regulations for Blasting" (6722-2014), for safety reasons, the minimum vibration velocity corresponding to the lowest frequency range (f0≤10Hz) is taken as the safe allowable vibration velocity v0 = 1.5cm / s. Referring to the experience of similar engineering sites, the Sadovsky formula parameters of the blasting area are determined: K = 409.53, β = 1.85. Substituting the parameters into formula (9) to calculate the single-hole charge Q under the vibration safety conditions of the protected object b =0.90kg.

[0171] Get Q a and Q b The smaller value of the two Q b As the initial single hole dosage Q0, that is, Q0 = 0.90 kg.

[0172] Step 3: Calculate the maximum initial stress of the blasthole wall.

[0173] Determine the charge length l of the blasthole according to the initial single-hole charge Q0 c , the charge length l is calculated by formula (10) c =0.71m. The water spacing length of each end of a single blasthole is l w From formula (11), we can get l w =0.1m.

[0174] The Starfield superposition method is used to calculate the maximum initial stress on the borehole wall, assuming that all equivalent spherical charges are detonated simultaneously. The maximum axial shock wave stress occurs at the center of the charge length of the borehole. To simplify the calculation, only the stress generated by the spherical charge in the half-section charge column at the center is superimposed. The transmission stress P on the borehole wall is obtained according to the continuous medium condition in the radial direction. r,t It is related to the wave impedance of rock and water medium. l c =0.71m,d c =0.04m,d e =0.049m,ρ e =1000kg / m 3 , r =2580kg / m 3 , w =1000kg / m 3 , W s =4142kJ / kg, W t =4200kJ / kg, α=2.21, B=72MPa, Q s =0.0788kg, d e , =0.0532m,ρ w =1000kg / m 3 , A=394MPa, ψ=1 / 8 Substituting into equations (12) and (13), we can obtain the maximum initial stress P of the blast hole wall. r,t =3187MPa.

[0175] Step 4: Determine the blasting time of the rock mass points at the protected object.

[0176] The hole wall transmission stress generated by the explosion of explosives decays as the propagation distance in the surrounding rock medium increases. The moment when the stress wave propagates to the rock mass point at the protected object reaches the maximum value is t s . Set the parameters η1 = 0.33, η2 = 0.58, ∈1 = 1.5, ∈2 = 0.67, r = 20m, C p =4000m / s, w=47140Substituting into formula (14) we get t s =0.64ms.

[0177] Stress at t j The moment decays to a relatively infinitesimal value, and the peak value of the stress wave is taken as 4×10 -3 times as the relative infinitesimal value of stress. t0 = 5 ms, G = 4 × 10 -3 Substituting into equation (15), we can get the blasting time t j =6ms.

[0178] Step 5: Determine the velocity response and maximum velocity of the rock mass particle vibration at the protected object.

[0179] The rock mass particles are forced to vibrate in the time period of t = 0 to 6 ms. b =0.04m is substituted into formula (16) to determine the displacement response of the single-degree-of-freedom rock mass system in the forced vibration stage, and then the velocity response ν in the forced vibration stage is determined according to formula (17): r (t), displacement and velocity response curves refer to Figure 2 .

[0180] The initial condition of free vibration is: r (t j )=8.96×10 -6 m, speed v r (t j )=-0.0348m / s and parameters ζ=0.08、ω d =626 / s, Substituting into equation (18), we can find the velocity response v in the free vibration stage: f (t).

[0181] The velocity response of the entire stage is v(t)=v r (t)+v f (t), draw the speed response curve of the whole stage. Analyze the speed response curve and get the maximum speed v max =3.48cm / s.

[0182] Step 6: Determine the velocity response main frequency and safe vibration speed of the rock mass points at the protected object during the entire vibration stage.

[0183] According to formula (19), the main frequency f1 = 95.57 Hz is obtained.

[0184] Referring to the allowable safety standards for blasting vibration in the "Safety Regulations for Blasting" (GB / 6722-2014), a new safe vibration speed v1=2.6cm / s is determined based on the main frequency.

[0185] Step 7: Determine the final single-hole dosage after optimization.

[0186] The actual vibration frequency f1 = 95.57 Hz and the safe vibration speed v1 = 2.6 cm / s obtained in step 6 are inconsistent with the assumed vibration frequency f0 = 10 Hz and the safe allowable vibration speed v0 = 1.5 cm / s in step 2. The actual f1 and v1 are used to replace the f0 and v0 in step 2. Compare the velocity response peak v obtained in step 5 1max =3.48cm / s and safe vibration speed v1, v maxIf it is greater than v1, the charge of the blasthole is too large. Based on the initial charge of the single hole Q0 = 0.90kg, the charge is reduced by ΔQ = 0.1kg to obtain the actual charge Q1 = Q0-1×ΔQ = 0.80kg. The actual Q1 is used to replace Q0 in step 2. The first cycle calculation is completed. The replaced actual charge of the blasthole Q1 is used to start the second cycle calculation and repeat steps 3 to 7, and so on. The velocity response peak value v obtained in the 5-cycle calculation is 5max =2.58cm / s is close to the safe allowable vibration velocity value v5=2.6cm / s. The dosage Q4 in the 4th cycle calculation is selected as the final actual dosage, that is, the final single-hole dosage is Q4=Q0-4×ΔQ=0.50kg.

[0187] Substitute the optimized blasthole charge Q4 = 0.50 kg as the initial single-hole charge Q0 into formula 10 and formula 11 to determine the optimized charge length l c,4 =0.4m and water interval length l w,4 =0.25m.

[0188] The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. All equivalent structural changes made using the contents of the present invention's specification and drawings, or directly / indirectly applied in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A method for determining the amount of charge in a single hole of water-interval charge blasting hole by hole under micro-vibration control conditions, characterized in that: The specific steps include: Step 1: Determine the explosive and blasthole parameters: Select the type of explosive for hole-by-hole blasting according to the properties of the blasted rock mass, and obtain the following parameters of the selected explosive: Explosive density ρ e ; Explosive unit consumption q; Determine the step height H according to the project site conditions and calculate the height w of the resistance line d : w d =(0.6~0.9)H (1) The diameter d of a single blasthole is determined based on the step height and the diameter of the drill rig used. b , and determine the hole spacing c and row spacing d at the same time: c=he d (2) d=(0.9~0.95)w d (3) Where, e is the proximity coefficient, e = 1.0 ~ 1.4; Extra deep length h c Determined by the following formula: h c =(0.15~0.35)w d (4) Blockage length h d Determined by the following formula: h d =(0.63~0.88)w d (5) The total length of the blasthole L is the step height H and the extra-deep length h c sum; The blasthole adopts radial water-uncoupled charge, and the radial water-uncoupled coefficient k is set d 1.2~2; Charge diameter d c Determined by the following formula: d c =d b k d (7) Step 2: Determine the initial single-hole dosage: The single hole dosage Q is calculated by volume method a : Q a =qcXH (8) In the formula: X = w when calculating the amount of medicine in the front row holes d , when calculating the dosage of the rear row holes, X = d; According to the type of building / structure protected in the explosion zone, a vibration main frequency f0 is assumed, and the safe allowable vibration velocity value v0 is determined by the vibration main frequency f0; According to v0 and Sadovsky's empirical formula, the single-hole charge Q under the vibration safety condition of the protected object is calculated. b ; In the formula: r is the distance from the explosion center, that is, the distance from the protected building / structure to the explosion source; K is the site coefficient, and β is the attenuation coefficient; Get Q a and Q b The smaller value of the two is taken as the initial single-hole dosage Q0; Step 3: Calculate the maximum initial stress of the blasthole wall: Determine the charge length l of the blast hole according to the initial single-hole charge Q0 c : The blasthole adopts a two-end water interval charging structure, the upper and lower water interval lengths are equal, and the length of each end water interval is l w Determined by the following formula: The Starfield superposition method is used to calculate the maximum initial stress P of the blasthole wall. r,t ; Step 4: Determine the blasting time of the rock mass points at the protected object; The hole wall transmission stress generated by the explosion of the explosive decays with the increase of the propagation distance in the surrounding rock medium. The stress wave pressure rise time t s It is found by the following formula: Where: Damping coefficient As the distance from the center of the explosion changes, the coefficients η1, η2, ∈1, and ∈2 are determined based on the full-scale tests of Atchison and Tournay; is a coefficient related to the rock longitudinal wave velocity and the blasthole radius, where c p is the longitudinal wave velocity of the shock wave when it propagates in the rock; Stress at t j The stress wave peak value is taken as the relative infinitesimal value of stress, and the duration is t j According to Newton's iteration method, we can get: Where: j is the number of iterations, and the starting calculation time is t0 = (8-10) × t s , after j iterations, the blasting time t is obtained j ; Step 5: Determine the velocity response and maximum vibration velocity of the rock mass point vibration at the protected object; Analyze the radial displacement and radial velocity of the rock per unit volume at the protected object. The rock mass point is between 0 and t j Forced vibration occurs in the time period, and the displacement response u of the single-degree-of-freedom rock mass system in the forced vibration stage is determined by structural dynamics r (t): Where: Z is the time lag function f(t) = Z(e -at -e -bt ), M is the mass of rock per unit volume at the protected object; ω is the circular frequency of the rock; δ is the distance attenuation coefficient of the stress wave; r b is the radius of the blast hole, r b =d b / 2; The radial velocity and displacement of the rock mass are derivative relations. The forced vibration velocity response v is determined according to formula (16): r (t): At time t>t j After that, the rock particles vibrate freely. The displacement u at time t1 in equations (16) and (17) is r (t j ) and speed v r (t1) is used as the initial condition of free vibration, and the free vibration velocity response v is obtained according to structural dynamics. f (t): Where: ζ is the damping ratio; ω d is the damping frequency, The velocity response of the entire stage is v(t) = ν r (t)+ν f (t), draw the speed response curve of the whole stage, and find the maximum speed response v 1max ; Step 6: Determine the velocity response main frequency and safe vibration speed of the rock mass points where the protected building / structure is located during the entire vibration stage: According to the velocity response curve in step 5, the rock vibration velocity response curve at the protected building / structure object is subjected to fast Fourier transform to obtain the actual vibration main frequency f1 of the velocity response; and a new safe vibration velocity v1 is determined according to the vibration main frequency f1; Step 7: Determine the final single-hole dosage after optimization: The actual vibration main frequency f1 and safe vibration speed v1 obtained in step 6 are used to replace the assumed vibration main frequency f0 and safe vibration speed v0 in step 2, and v1 is compared with the velocity response peak value v obtained in step 5. 1max Compare: If v 1max Less than v1, increase the dosage ΔQ based on the initial single-hole dosage Q0; If v 1max If it is greater than v1, the dosage ΔQ is reduced based on the initial single-hole dosage Q0; Finally, the actual drug dosage Q1 = Q0 ± ΔQ is obtained, and the actual Q1 is used to replace Q0 in step 2. The first cycle calculation is completed. Use the actual blast hole charge Q1 to start the second cycle calculation and repeat steps 3 to 7 until k cycles have passed and the safe vibration velocity v is obtained. k Equal to the velocity response peak value v kmax When the actual drug amount Q in the k-1th cycle calculation is selected k-1 Determine the final dosage, that is, the final single-hole dosage is Q k-1 =Q0±(k-1)×ΔQ.

2. The method for determining the amount of charge for single-hole blasting with water-interval charge under micro-vibration control conditions according to claim 1 is characterized in that: In step 1, the super-deep length h c When determining: When the rock is hard rock: h c =0.35w d , when the rock is soft, select h c =0.15w d .

3. The method for determining the amount of charge for single-hole blasting with water-interval charge under micro-vibration control conditions according to claim 1 is characterized in that: In step 1, the radial water decoupling coefficient k is determined based on the wave impedance matching relationship between the water medium and the rock. d ; Where: η is the energy utilization rate, ρ r is the rock density, ρ w is the density of water, k w is the compression modulus of water; ρ e is the density of explosive; D is the detonation velocity of explosive.

4. The method for determining the amount of charge for single-hole blasting with water-interval charge under micro-vibration control conditions according to claim 1 is characterized in that: In step 2, the main vibration frequency f0 and the safe allowable vibration velocity value v0 are determined according to the "Explosive Safety Regulations".

5. The method for determining the charge amount of a single hole in water-interval charge hole-by-hole blasting under micro-vibration control conditions according to claim 1 is characterized in that: In step 3, the Starfield superposition method is used to calculate the maximum incident stress P r,i Here’s how: Where: Represents the largest positive integer not greater than *; l c is the actual charge length; is the equivalent spherical package diameter, W s W is the specific detonation heat of the actual explosive; t is the specific explosion heat of TNT explosive; α is the attenuation coefficient of the peak value of shock wave stress propagating along the axial direction of the blast hole; B is the JWL state equation parameter; The amount of medicine in the final medicine package; is the diameter of the terminal drug package; Considering the influence of radial water decoupling on stress: the water between the charge and the hole wall is the medium for the stress wave to enter the hole wall. According to the continuous medium condition, the maximum transmission stress P of the shock wave generated in the blasthole is r,t Also called the maximum initial stress of the blasthole wall is determined by the following formula: Where: A and ψ are constants obtained from Baum's experiment; The maximum initial stress P of the blast hole wall is obtained by formula (13): r,t .

6. The method for determining the amount of charge for single-hole blasting with water-interval charge under micro-vibration control conditions according to claim 1 is characterized in that: In step six, the vibration main frequency f1 and the safe allowable vibration velocity value v1 are determined according to the "Explosive Safety Regulations".

7. The method for determining the charge amount of a single hole in water-interval charge hole-by-hole blasting under micro-vibration control conditions according to claim 1 is characterized in that: In step seven, ΔQ is 1% to 11% of the initial single-hole drug volume Q0.

8. The method for determining the charge amount of a single hole in water-interval charge hole-by-hole blasting under micro-vibration control conditions according to claim 1 is characterized in that: At the end of step 7, the optimized blast hole charge Q k-1 Substitute the initial single-hole charge Q0 into formula 10 and formula 11 to determine the optimized charge length l c Length of water interval l w .

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