Method and system for determining water interval charging single-hole blasting explosive quantity

Abstract

The invention discloses a method and a system for determining single-hole blasting explosive quantity of water interval explosive loading. The method comprises the following steps: firstly, determining initial single-hole explosive quantity; obtaining the maximum initial stress of the hole wall of the blast hole according to the blasting superposed stress of the plurality of spherical cartridges of the charging section, and determining the blasting action time of the rock mass point at the protected object by combining a Newton iteration method; according to the forced vibration of the blasting action time period of the rock mass point of the protected object, free vibration speed response is determined; according to the forced vibration speed response and the free vibration speed response, a corresponding speed curve of the stress propagation stage is obtained, fast Fourier transform is carried out on a rock vibration speed response curve of the protected object, the actual vibration dominant frequency of the speed response is obtained, and a new safe vibration speed is determined according to the actual vibration dominant frequency; and the safe vibration velocity and the velocity response peak value are compared to update the initial single-hole explosive quantity to obtain the actual blast hole explosive quantity, and the final single-hole explosive quantity is obtained through iterative optimization. According to the method, the vibration effect safety of the surrounding protected building can be guaranteed, the explosive energy is fully utilized, the construction cost is saved, and the blasting rock breaking effect is improved.

Description

Technical Field

[0001] The invention relates to the field of urban rock mass blasting construction, and in particular to a method for determining the charge amount of a water-interval charging single-hole blasting. 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 a more prominent blasting vibration effect problem in the surrounding buildings (structures), causing damage to the buildings (structures) or even collapse. 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 blast hole delay method. Each blast hole is detonated separately in space and time according to a specific detonation sequence. The first blast hole creates more free surfaces for the subsequent blast holes, 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, hole-by-hole blasting strictly controls the (maximum) single hole charge and total charge of each blasting, resulting in slow progress and low efficiency of 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] In view of the problems existing in the prior art, the present invention provides a method for determining the amount of water-interval charging for single-hole blasting, which can not only ensure the safety of the vibration effect of the surrounding protected buildings, but also achieve high-efficiency construction.

[0006] The present invention is achieved through the following technical solutions:

[0007] A method for determining the amount of explosives for a water-interval-charged single-hole blasting comprises the following steps:

[0008] Step 1: Determine the single-hole charge Q under vibration safety conditions of the protected object according to the vibration main frequency f0 and the safe allowable vibration velocity value v0 of the protected object in the blasting area. b , according to the single hole dosage Q b Determine the initial single-hole dosage Q0;

[0009] Step 2: Determine the charge length l of the blast hole according to the initial single-hole charge Q0 c The length of the water gap between the upper and lower ends of the blasthole is l w ; Divide the charge section into multiple spherical charges of equal volume according to the charge length and charge diameter, and obtain the maximum initial stress of the blast hole wall according to the superimposed stress of the multiple spherical charges blasting;

[0010] Step 3: Determine the blasting time of the rock mass points at the protected object according to the maximum initial stress of the blasthole wall after the explosion of the explosives and in combination with the Newton iteration method;

[0011] Step 4: According to the forced vibration of the rock mass particles at the protected object during the blasting period, determine the displacement response and velocity response of the single-degree-of-freedom rock mass system during the forced vibration stage, and determine the free vibration velocity response ν in combination with structural dynamics.f (t); According to the forced vibration velocity response and free vibration velocity response ν f (t), obtain the velocity response curve of the stress propagation stage, and determine the velocity response peak value according to the velocity response curve;

[0012] Step 5: Perform fast Fourier transform on the rock vibration velocity response curve at the protected object to obtain the actual vibration main frequency of the velocity response, and determine a new safe vibration velocity v1 according to the actual vibration main frequency;

[0013] Step 6: Use the actual vibration main frequency and safe vibration speed v1 to replace the vibration main frequency f0 and safe vibration speed v0 in step 1, and compare the safe vibration speed v1 with the speed response peak value v 1max Compare, update the initial single hole charge Q0 according to the comparison result to get the actual blast hole charge Q1, and repeat steps 1-6 until the safe vibration speed v k Equal to the velocity response peak value v kmax The final single-hole drug dose is obtained.

[0014] Preferably, the method for determining the initial single-hole drug dose in step 1 comprises:

[0015] Determine the single hole dosage Q using the volumetric method a ;

[0016] The vibration main frequency is set for the protected object in the blasting area, and the safe allowable vibration speed is determined according to the vibration main frequency. The single-hole charge Q under the vibration safety condition of the protected object is determined according to the safe allowable vibration speed combined with the Sadovsky method. b ;

[0017] Compare single hole dosage Q a Single hole charge Q under vibration safety conditions b , and take the smaller value of the dosage as the initial single-hole dosage Q0.

[0018] Preferably, in step 2, the charge length l of the blast hole c The length of the water gap between the upper and lower ends of the blasthole is l w Methods for determining include:

[0019] Determine the charge length l of the blast hole according to the initial single-hole charge Q0 c , determine the water interval length at the upper and lower ends of the blasthole based on the total length of the blasthole, the blasthole charging length and the blasthole blocking length.

[0020] Preferably, the method for determining the charge diameter includes:

[0021] According to the radial water decoupling coefficient of the radial water decoupling charge and the diameter d of the blasthole b , determine the charge diameter d c .

[0022] Preferably, the method for determining the maximum initial stress of the blasthole wall comprises:

[0023] First, determine the maximum incident stress P of the shock wave generated by the explosion at the center of the charge section at the hole wall. r,i , according to the maximum incident stress P at the hole wall r,i Determine the maximum initial stress of the blasthole wall.

[0024] Preferably, the expression of the maximum initial stress of the blasthole wall is as follows:

[0025]

[0026] Among them, A and ψ are constants, P r,i is the maximum incident stress at the hole wall, ρ w is the density of water, ρ r is the rock density, c p is the longitudinal wave velocity when the shock wave propagates in the rock.

[0027] Preferably, in step 3, the stress wave pressure rise time of the hole wall transmission stress propagating to the protected object after the explosion of the explosive is determined in combination with the Newton iteration method to determine the blasting action time of the rock mass particles at the protected object, and the expression is as follows:

[0028]

[0029] in, j is the number of iterations.

[0030] Preferably, the free vibration velocity response v in step 4 is f The expression of (t) is as follows:

[0031]

[0032] Where t>t j ;ζ is the damping ratio;ω d is the damping frequency, ω is the circular frequency of rock; δ is the distance attenuation coefficient of stress wave.

[0033] Preferably, the method for determining the actual blasthole charge Q1 is as follows:

[0034] If v 1max Less than v1, increase the dosage ΔQ based on the initial single-hole dosage Q0;

[0035] If v 1max If it is greater than v1, the dosage ΔQ is reduced based on the initial single-hole dosage Q0;

[0036] The final charging length and water interval length are determined based on the final single-hole charge.

[0037] A system for determining the amount of charge for a water-interval-charged single-hole blasting, comprising:

[0038] The initial single-hole charge module is used to determine the single-hole charge Q under the vibration safety condition of the protected object according to the vibration main frequency f0 and the safe allowable vibration velocity value v0 of the protected object in the blasting area. b , according to the single hole dosage Q b Determine the initial single-hole dosage Q0;

[0039] Initial stress module, used to determine the charge length l of the blast hole according to the initial single hole charge Q0 c The length of the water gap between the upper and lower ends of the blasthole is l w ; Divide the charge section into multiple spherical charges of equal volume according to the charge length and charge diameter, and obtain the maximum initial stress of the blast hole wall according to the superimposed stress of the multiple spherical charges blasting;

[0040] The blasting time module is used to determine the blasting time of the rock mass points at the protected object based on the maximum initial stress of the blasthole wall after the explosion of the explosives and in combination with the Newton iteration method;

[0041] The velocity peak module is used to determine the displacement response and velocity response of the single-degree-of-freedom rock mass system during the forced vibration stage according to the forced vibration of the rock mass particles at the protected object during the blasting action period, and to determine the free vibration velocity response ν in combination with structural dynamics. f (t); According to the forced vibration velocity response and free vibration velocity response ν f (t), obtain the velocity response curve of the stress propagation stage, and determine the velocity response peak value according to the velocity response curve;

[0042] The safe vibration speed update module is used to perform fast Fourier transform on the rock vibration speed response curve at the protected object to obtain the actual vibration main frequency of the speed response, and determine the new safe vibration speed v1 according to the actual vibration main frequency;

[0043] The drug dosage output module is used to replace the vibration main frequency f0 and safety vibration speed v0 in step 1 with the actual vibration main frequency and safety vibration speed v1, and compare the safety vibration speed v1 with the speed response peak value v 1max Compare, update the initial single hole charge Q0 according to the comparison result to get the actual blast hole charge Q1, and repeat the above modules until the safe vibration speed v k Equal to the velocity response peak value v kmax The final single-hole drug dose is obtained.

[0044] Compared with the prior art, the present invention has the following beneficial technical effects:

[0045] The invention provides a method for determining the amount of explosives for a single-hole blasting with water-interval charge. The method comprises the following steps: dividing a charge bag of a charge section into a plurality of spherical charge bags of equal volume, obtaining the maximum initial stress of a blasthole wall according to the superimposed stress of the blasting of the plurality of spherical charge bags, determining the blasting action time of a rock mass particle at a protected object according to the maximum initial stress, and then obtaining the speed response and the maximum vibration velocity of the rock mass particle vibration at the protected object, performing fast Fourier transform on the rock vibration speed response curve at the protected object, obtaining the actual vibration main frequency of the speed response, determining a new safe vibration velocity according to the actual vibration main frequency, and then iteratively optimizing the single-hole charge amount to obtain the final single-hole charge amount. The method can ensure the safety of the vibration effect of surrounding protected buildings and realize high-efficiency construction, make full use of the explosive energy, save the construction cost, and improve the blasting rock breaking effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 It is a flow chart of the method for determining the charge quantity for water-interval charging single-hole blasting of the present invention;

[0047] Figure 2 The displacement and velocity response curves of the object to be protected by the present invention.

[0048] Figure 3 It is a schematic structural diagram of the charge section of the present invention. DETAILED DESCRIPTION

[0049] The present invention will be further described in detail below in conjunction with the accompanying drawings, which are intended to explain the present invention rather than to limit it.

[0050] A method for determining the amount of explosives for a water-interval-charged single-hole blasting comprises the following steps:

[0051] Step 1: Determine the resistance line w according to the step height of the blasting d , according to the resistance line w d Determine the diameter, row spacing and hole spacing of the blastholes on the step; according to the resistance line w d The ultra-deep length h of the blasting is determined by combining the rock hardness of the blasting area. c and the blockage length h d ; According to the step height H and the extra-deep length h c Determine the total length L of the blasthole.

[0052] According to the radial water decoupling coefficient of the radial water decoupling charge and the diameter d of the blasthole b , determine the charge diameter d c .

[0053] S1.1. Determine the parameters of explosives and blastholes: Select the appropriate type of explosives for hole-by-hole blasting according to the properties of the blasted rock mass, and obtain the following parameters of the selected explosives: Explosive density ρ eand explosive unit consumption q;

[0054] Determine the step height H according to the project site conditions and calculate the resistance line w d Height:

[0055] w d =(0.6~0.9)H (1)

[0056] Blasting Bench Height is an important concept in blasting projects such as mining and civil engineering. It refers to the vertical height of the step when performing step blasting. This height is a key parameter that must be considered when designing a blasting project, because it directly affects the layout of blastholes, the amount of explosives used, the blasting effect, and the safety and economy of the project. In step blasting, the rock surface is usually divided into several steps of the same height, and a certain number of blastholes are arranged on each step to reduce the height of the rock surface through blasting. The determination of the step height needs to consider factors such as the nature of the rock, the needs of the project, safety standards, and cost-effectiveness. The selection of the step height has a decisive influence on the efficiency and effect of the entire blasting project.

[0057] The resistance line (Burden) refers to the vertical distance from the center of the blasthole to the free surface (i.e., the unconstrained surface of the rock, such as faults, cracks, free surfaces, etc.) during blasting. During the blasting process, the resistance of the rock in front of the blasthole to the blasting energy. It is a key factor affecting the blasting effect, which is usually related to the arrangement of the blasthole, the type and amount of explosives, the properties of the rock, etc. When designing blasting, the length of the resistance line will affect the selection of the diameter, row spacing and hole spacing of the blasthole to ensure that the blasting energy can be effectively transmitted to the rock to achieve the expected crushing effect.

[0058] S1.2. Determine the diameter d of a single blasthole 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:

[0059] c=ew d (2)

[0060] d=(0.9~0.95)w d (3)

[0061] Where, e is the proximity coefficient, e = 1.0 ~ 1.4;

[0062] S1.3. Determine the super-deep length h based on the resistance line c , the formula is as follows:

[0063] h c =(0.15~0.35)w d (4)

[0064] When the rock is hard, choose a slightly larger super-depth value; when the rock is soft, choose a slightly smaller super-depth value;

[0065] The extra-deep length refers to the part where the actual drilling depth of the blasthole exceeds the step height. In order to ensure the blasting effect, a certain extra-depth needs to be added on the basis of the step height to overcome the hardness and strength of the rock and prevent the rock blocks after blasting from being too large or incompletely broken. The choice of extra-deep length usually depends on the hardness of the rock, the design requirements of the blasting, and safety considerations. Extra-deep can improve the crushing effect of blasting, but it will also increase the cost and workload of drilling.

[0066] S1.4, blocking length h d Determined by the following formula:

[0067] h d =(0.63~0.88)w d (5)

[0068] Muck Length or Plug Length refers to the length of the filling material at the bottom of the blasthole used to prevent the escape of explosive gases and increase the rock crushing effect.

[0069] S1.5. The total length of the blasthole L is the sum of the step height H and the extra-deep length h. c sum;

[0070] S1.6. The blasthole adopts radial water-uncoupled charge, and determines a suitable radial water-uncoupled coefficient k according to the matching relationship between water medium and rock wave impedance. d As the energy utilization rate η increases, the radial water decoupling coefficient decreases. According to practical experience, when k d When k > 2, the shock wave stress generated by the fine grain column in the blast hole is too small; d When k is less than 1.2, the radial water volume in the borehole is too small to promote the "water wedge" effect; when k d When 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;

[0071]

[0072] 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, ρ w is the density of water, k wis the compression modulus of water; ρ e is the density of explosives; D is the detonation velocity of explosives;

[0073] According to the radial water uncoupling coefficient and the diameter d of a single blasthole b Determine the charge diameter d c , the expression is as follows:

[0074] d c =d b k d (7)

[0075] Step 2: Determine the single hole dosage Q using the volume method a ; According to the safe allowable vibration velocity value v0 of the protected object and Sadovsky method, determine the single hole charge Q under the vibration safety condition of the protected object b ;

[0076] According to the single hole dosage Q a Single hole charge Q under vibration safety conditions b Determine the initial single hole dosage Q0.

[0077] The specific process includes the following:

[0078] S2.1. Determine the initial single-hole dosage:

[0079] The single hole dosage Q is calculated by volume method a :

[0080] Q a =qcXH (8)

[0081] In the formula: X = w when calculating the amount of medicine for the front row holes d , when calculating the amount of explosives in the rear row holes, X = d, q is the unit consumption of explosives, and c is the hole distance;

[0082] S2.2. 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);

[0083] According to the safe allowable vibration velocity value v0 and Sadovsky's empirical formula, the single hole charge Q under the vibration safety condition of the protected object is calculated. b ;

[0084]

[0085] 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;

[0086] S2.3, take the single hole dose Q a Single hole charge Q under vibration safety conditions b The smaller value of the two is taken as the initial single-hole dose Q0.

[0087] Step 3: Determine the charge length l of the blast hole according to the initial single-hole charge Q0 c , according to the length of the blasthole and the length of the charge in the blasthole l c And the blocking length determines the water interval length l at the upper and lower ends of the blasthole w ;

[0088] The charge bag with the same charge length is divided into multiple spherical charges of equal volume. The blasting stresses of multiple spherical charges are superimposed to obtain the maximum initial stress of the borehole wall.

[0089] The maximum initial stress of the blasthole wall includes the following processes:

[0090] S3.1. Determine the charge length l of the blast hole according to the initial single-hole charge Q0 c :

[0091]

[0092] 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:

[0093]

[0094] For the entire blasthole length L, 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 ;

[0095] S3.2. 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 detonate 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 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.

[0096] 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 :

[0097]

[0098] 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;

[0099] S3.3. Consider 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 blast hole r,t Also called the maximum initial stress of the blasthole wall is determined by the following formula:

[0100]

[0101] Where: A and ψ are constants obtained from Baum's experiment;

[0102] The maximum initial stress P of the blast hole wall is obtained by formula (13): r,t;

[0103] Step 4: According to the stress wave rise time of the hole wall transmission stress after the explosion of the explosives propagating to the protected object, the blasting time of the rock mass particles at the protected object is determined in combination with the Newton iteration method, which specifically includes the following processes:

[0104] S4.1. The transmitted stress of the hole wall generated by the explosion of explosives 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:

[0105]

[0106] Where: Damping coefficient As the distance from the center of the explosion changes, the coefficients η1, η2, ε1, and ε2 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.

[0107] S4.2, 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:

[0108]

[0109] 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 .

[0110] Step 5: According to the forced vibration occurring at the blasting time end of the rock mass point at the protected object, the displacement response and the forced vibration velocity response of the single-degree-of-freedom rock mass system at the forced vibration stage are determined in combination with structural dynamics;

[0111] The displacement response and forced vibration velocity response in the forced vibration stage are taken as the initial conditions of free vibration, and the free vibration velocity response ν is obtained according to structural dynamics. f (t), according to the forced vibration velocity response and free vibration velocity response ν f (t), obtain the speed response curve of the whole stage, and determine the maximum speed response value according to the speed response curve.

[0112] S5.1. Analyze the radial displacement and radial velocity of the rock per unit volume at the protected object:

[0113] The rock mass point is between 0 and t jForced 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):

[0114]

[0115] 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;

[0116] The radial velocity and displacement of the rock mass are derivative relations. The forced vibration velocity response ν is determined according to formula (16): r (t):

[0117]

[0118] S5.2. 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):

[0119]

[0120] Where: t>t j ;ζ is the damping ratio;ω d is the damping frequency,

[0121] S5.3, the speed response of the whole stage is v(t) = ν r (t)+ν f (t), draw the speed response curve of the whole stage, and find the maximum value v of the speed response (curve) 1max ;

[0122] Step 6: According to the velocity response curve, perform fast Fourier transform on the rock vibration velocity response curve at the protected object to obtain the actual vibration main frequency of the velocity response, and determine the new safe vibration speed v1 according to the actual vibration main frequency.

[0123] 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;

[0124] Step 7: Use the actual vibration main frequency f1 and safe vibration speed v1 to replace the assumed vibration main frequency f0 and safe vibration speed v0, and compare the safe vibration speed v1 with the speed response peak value v 1max Compare and update the initial single-hole charge Q0 according to the comparison result to obtain the actual blasthole charge Q1;

[0125] S7.1. Replace the assumed vibration main frequency f0 and safety vibration speed v0 in step 2 with the actual vibration main frequency f1 and safety vibration speed v1 obtained in step 6, and compare v1 with the velocity response peak value v obtained in step 5. 1max Compare:

[0126] If v 1max Less than v1, increase the dosage ΔQ based on the initial single-hole dosage Q0;

[0127] If v 1max If it is greater than v1, the dosage ΔQ is reduced based on the initial single-hole dosage Q0; ΔQ is generally taken as 1% to 11% of the initial single-hole dosage Q0.

[0128] Finally, the actual drug dosage Q1=Q0±ΔQ is obtained, and the actual Q1 is used to replace Q0 in step 2. At this point, the first cycle calculation is completed.

[0129] Step 8: Repeat steps 3-7 until the safe vibration speed v k Equal to the velocity response peak value v kmax When the final single-hole charge is obtained, the charge length and water interval length are determined according to the final single-hole charge.

[0130] Use the actual blast hole charge Q1 to start the second cycle calculation and repeat steps 3-7 until the safe vibration velocity v is obtained after k cycles. 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;

[0131] 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 lw,k-1 .

[0132] Example 1

[0133] See also Figure 1-3 , a method for determining the amount of water-interval charge for single-hole blasting, comprising the following steps:

[0134] Step 1: Determine the explosive and blasthole parameters.

[0135] 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.

[0136] 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.

[0137] 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.

[0138] 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.

[0139] 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.

[0140] Step 2: Determine the initial single-hole dosage.

[0141] 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.

[0142] 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.

[0143] 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.

[0144] Step 3: Calculate the maximum initial stress of the blasthole wall.

[0145] 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.

[0146] 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.

[0147] Step 4: Determine the blasting time of the rock mass points at the protected object.

[0148] 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 .

[0149] Set the parameters η1 = 0.33, η2 = 0.58, ε1 = 1.5, ε2 = 0.67, r = 20m, C p =4000m / s, w=47140Substituting into formula (14) we get t s =0.64ms.

[0150] 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 get the blasting time t j =6ms.

[0151] Step 5: Determine the velocity response and maximum velocity of the rock mass point vibration at the protected object.

[0152] 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 .

[0153] The initial condition of free vibration: ur (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 ν in the free vibration stage: f (t).

[0154] 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. Analyze the speed response curve and get the maximum speed v max =3.48cm / s.

[0155] 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.

[0156] Main frequency f1 = 95.57 Hz.

[0157] With reference to the allowable safety standards for blasting vibration in the Safety Regulations for Blasting (GB / 6722-2014), a new safe vibration velocity v1=2.6cm / s is determined based on the main frequency.

[0158] Step 7: Determine the final optimized single-hole dosage.

[0159] 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 value v obtained in step 5 1max =3.48cm / s and safe vibration speed v1, v max If 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.

[0160] 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.

[0161] Example 2

[0162] A system for determining the amount of charge for a water-interval charging single-hole blasting, comprising:

[0163] The initial single-hole charge module is used to determine the single-hole charge Q under the vibration safety condition of the protected object according to the vibration main frequency f0 and the safe allowable vibration velocity value v0 of the protected object in the blasting area. b , according to the single hole dosage Q b Determine the initial single-hole dosage Q0;

[0164] Initial stress module, used to determine the charge length l of the blast hole according to the initial single hole charge Q0 c The length of the water gap between the upper and lower ends of the blasthole is l w ; Divide the charge section into multiple spherical charges of equal volume according to the charge length and charge diameter, and obtain the maximum initial stress of the blast hole wall according to the superimposed stress of the multiple spherical charges blasting;

[0165] The blasting time module is used to determine the blasting time of the rock mass points at the protected object based on the maximum initial stress of the blasthole wall after the explosion of the explosives and in combination with the Newton iteration method;

[0166] The velocity peak module is used to determine the displacement response and velocity response of the single-degree-of-freedom rock mass system during the forced vibration stage according to the forced vibration of the rock mass particles at the protected object during the blasting action period, and to determine the free vibration velocity response ν in combination with structural dynamics. f (t); According to the forced vibration velocity response and free vibration velocity response ν f (t), the velocity response curve of the stress propagation stage is obtained, and the velocity response peak value is determined according to the velocity response curve.

[0167] The safe vibration speed update module is used to perform fast Fourier transform on the rock vibration speed response curve at the protected object to obtain the actual vibration main frequency of the speed response, and determine the new safe vibration speed v1 according to the actual vibration main frequency;

[0168] The drug dosage output module is used to replace the vibration main frequency f0 and safety vibration speed v0 in step 1 with the actual vibration main frequency and safety vibration speed v1, and compare the safety vibration speed v1 with the speed response peak value v 1max Compare, update the initial single hole charge Q0 according to the comparison result to get the actual blast hole charge Q1, and repeat the above modules until the safe vibration speed v k Equal to the velocity response peak value vkmax The final single-hole drug dose is obtained.

[0169] The present invention provides a method for determining the amount of explosives for a single-hole blasting with water-interval charging. The method adopts a blasting method with water-interval radial water-uncoupled charging at both ends to reduce the impact of dust and noise on the surrounding environment, while realizing environmentally friendly and ecological blasting construction. The axial and radial water media 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 the shock wave by reducing the peak value of the hole wall stress. At the same time, by increasing the hole wall stress action time, the rock crushing range and uniform blasting block size can be significantly increased, thereby making full use of the energy of the explosives, saving construction costs, and improving the blasting rock breaking effect. It not only strictly abides by the current blasting safety regulations and ensures the safety of the vibration effect of the protected building / structure, but also maximizes the optimization of the single-hole charge on the premise of meeting the micro-vibration control target, thereby improving the construction efficiency of urban rock excavation projects.

[0170] The above contents are only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A method for determining the amount of explosives for single-hole blasting with water-interval charging, It is characterized in that The steps include: Step 1: According to the vibration main frequency f of the object to be protected in the blasting area 0 and safe allowable vibration velocity value v 0 Determine the single hole charge Q under vibration safety conditions of the protected object b , according to the single hole dosage Q b Determine the initial single hole dose Q 0 ; Step 2: According to the initial single hole dosage Q 0 Determine the length of the blasthole charge l c The length of the water gap between the upper and lower ends of the blasthole is l w ; Divide the charge section into multiple spherical charges of equal volume according to the charge length and charge diameter, and obtain the maximum initial stress of the blast hole wall according to the superimposed stress of the multiple spherical charges blasting; Step 3: Determine the blasting time of the rock mass points at the protected object according to the maximum initial stress of the blasthole wall after the explosion of the explosives and in combination with the Newton iteration method; Step 4: According to the forced vibration of the rock mass particles at the protected object during the blasting period, determine the displacement response and velocity response of the single-degree-of-freedom rock mass system during the forced vibration stage, and determine the free vibration velocity response ν in combination with structural dynamics. f (t); According to the forced vibration velocity response and free vibration velocity response ν f (t), obtain the velocity response curve of the stress propagation stage, and determine the velocity response peak value according to the velocity response curve; Step 5: Perform fast Fourier transform on the rock vibration velocity response curve at the protected object to obtain the actual vibration main frequency of the velocity response, and determine the new safe vibration velocity v according to the actual vibration main frequency. 1 ; Step 6: Use the actual vibration main frequency and safe vibration speed v 1 Substitute the vibration frequency f in step 1 0 and safe vibration speed v 0 , and the safe vibration speed v 1 With the speed response peak v 1max Compare and update the initial single-hole dosage Q according to the comparison results 0 Get the actual blast hole charge Q 1 , and repeat steps 1-6 until the safe vibration speed v k Equal to the velocity response peak value v kmax The final single-hole drug dose is obtained.

2. A method for determining the amount of explosives for single-hole blasting with water-interval charging according to claim 1, It is characterized in that The method for determining the initial single-hole drug dose in step 1 comprises: Determine the single hole dosage Q using the volumetric method a ; The vibration main frequency is set for the protected object in the blasting area, and the safe allowable vibration speed is determined according to the vibration main frequency. The single-hole charge Q under the vibration safety condition of the protected object is determined according to the safe allowable vibration speed combined with the Sadovsky method. b ; Compare single hole dosage Q a Single hole charge Q under vibration safety conditions b , take the smaller value of the dosage as the initial single hole dosage Q 0 .

3. A method for determining the amount of explosives for water-interval charging single-hole blasting according to claim 1, It is characterized in that The length of the charge in the blast hole in step 2 is l c The length of the water gap between the upper and lower ends of the blasthole is l w Methods for determining include: According to the initial single hole dosage Q 0 Determine the charge length l of the blast hole c , determine the water interval length at the upper and lower ends of the blasthole based on the total length of the blasthole, the blasthole charging length and the blasthole blocking length.

4. A method for determining the amount of explosives for water-interval charging single-hole blasting according to claim 3, It is characterized in that The method for determining the charge diameter comprises: According to the radial water decoupling coefficient of the radial water decoupling charge and the diameter d of the blasthole b , determine the charge diameter d c .

5. A method for determining the amount of charge for water-interval charging single-hole blasting according to claim 1 or 3, It is characterized in that The method for determining the maximum initial stress of the blasthole wall comprises: First, determine the maximum incident stress P of the shock wave generated by the explosion at the center of the charge section at the hole wall. r,i , according to the maximum incident stress P at the hole wall r,i Determine the maximum initial stress of the blasthole wall.

6. A method for determining the amount of explosives for water-interval charging single-hole blasting according to claim 5, It is characterized in that The expression of the maximum initial stress of the blasthole wall is as follows: Among them, A and ψ are constants, P r,i is the maximum incident stress at the hole wall, ρ w is the density of water, ρ r is the rock density, c p is the longitudinal wave velocity when the shock wave propagates in the rock.

7. A method for determining the amount of charge for water-interval charging single-hole blasting according to claim 1, It is characterized in that In step 3, the stress wave pressure rise time of the hole wall transmission stress propagating to the protected object after the explosion of the explosive is determined by combining the Newton iteration method with the blasting action time of the rock mass particles at the protected object. The expression is as follows: in, j is the number of iterations.

8. A method for determining the amount of charge for water-interval charging single-hole blasting according to claim 1, It is characterized in that The free vibration velocity response ν described in step 4 f The expression of (t) is as follows: Where t>t j ;ζ is the damping ratio;ω d is the damping frequency, ω is the circular frequency of rock; δ is the distance attenuation coefficient of stress wave.

9. A method for determining the amount of explosives for water-interval charging single-hole blasting according to claim 1, It is characterized in that The actual blast hole charge Q 1 The method of determining is as follows: If v 1max Less than v 1 , at the initial single hole dose Q 0 Increase the dosage ΔQ on the basis of If v 1max Greater than v 1 , at the initial single hole dose Q 0 Reduce the dosage ΔQ based on The final charging length and water interval length are determined based on the final single-hole charge.

10. A system for executing the method for determining the charge quantity for water-interval charging single-hole blasting according to any one of claims 1 to 9, It is characterized in that include: The initial single-hole charge module is used to determine the vibration frequency f of the object to be protected in the blasting area. 0 and safe allowable vibration velocity value v 0 Determine the single hole charge Q under vibration safety conditions of the protected object b , according to the single hole dosage Q b Determine the initial single hole dose Q 0 ; The initial stress module is used to calculate the initial single hole dose Q 0 Determine the length of the blasthole charge l c The length of the water gap between the upper and lower ends of the blasthole is l w ; Divide the charge section into multiple spherical charges of equal volume according to the charge length and charge diameter, and obtain the maximum initial stress of the blast hole wall according to the superimposed stress of the multiple spherical charges blasting; The blasting time module is used to determine the blasting time of the rock mass points at the protected object based on the maximum initial stress of the blasthole wall after the explosion of the explosives and in combination with the Newton iteration method; The velocity peak module is used to determine the displacement response and velocity response of the single-degree-of-freedom rock mass system during the forced vibration stage according to the forced vibration of the rock mass particles at the protected object during the blasting action period, and to determine the free vibration velocity response ν in combination with structural dynamics. f (t); According to the forced vibration velocity response and free vibration velocity response ν f (t), obtain the velocity response curve of the stress propagation stage, and determine the velocity response peak value according to the velocity response curve; The safe vibration speed update module is used to perform fast Fourier transform on the rock vibration speed response curve at the protected object to obtain the actual vibration main frequency of the speed response, and determine the new safe vibration speed v according to the actual vibration main frequency. 1 ; The dosage output module is used to use the actual vibration main frequency and safe vibration speed v 1 Substitute the vibration frequency f in step 1 0 and safe vibration speed v 0 , and the safe vibration speed v 1 With the speed response peak v 1max Compare and update the initial single-hole dosage Q according to the comparison results 0 Get the actual blast hole charge Q 1 , and repeat the above modules until the safe vibration speed v k Equal to the velocity response peak value v kmax The final single-hole drug dose is obtained.

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