CN111241679B - Tunnel blasting parameter design method based on digital electronic detonator detonation - Google Patents
Tunnel blasting parameter design method based on digital electronic detonator detonation Download PDFInfo
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
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Abstract
The invention provides a tunnel blasting parameter design method based on digital electronic detonator initiation, which is particularly suitable for tunnel blasting with high requirement on safe vibration speed control. The invention can realize high-efficiency footage and vibration control in urban tunnel blasting.
Description
Technical Field
The invention relates to a blasting parameter design method, which mainly aims at tunnel blasting excavation engineering initiated by a digital electronic detonator.
Background
The application of the digital electronic detonator is a great progress of engineering blasting, and represents the development direction of blasting technology. Compared with the common detonator, the delay accuracy of the digital electronic detonator is improved by more than 10 times, and the number of the initiation sections is increased by hundreds of times. The digital electronic detonators are used in tunnel excavation, so that blasting vibration can be obviously reduced, and in recent decades, the digital electronic detonators are increasingly used in tunnels, particularly urban tunnels, so that good blasting and vibration reduction effects are obtained.
Although the performance indexes of the digital detonator are very advanced, the characteristics and the potential of the digital detonator are not fully exerted in the engineering at present, and one important reason is that a digital electronic detonator blasting design method which is a system and has strict theoretical support does not exist at present. Taking the key parameters of the tunnel blasting design, namely the initiation explosive quantity and the time difference (most of the other parameters can be deduced according to the parameters) as an example: the former is still calculated according to the Sa's formula at present, and the calculation result has great discreteness and is often inconsistent with the actual situation; the design method for time delay between holes is divided into two types: the method is determined by combining engineering experience with field tests, needs to be adjusted for many times according to specific engineering, is relatively complex and has no universal applicability; the other type of half-cycle phase-staggered vibration reduction calculation method proposed based on the waveform theory simplifies the vibration waveform into damped cosine waves, but the actual blasting vibration waveform is not a strict periodic wave, and the blasting vibration wave is random due to the complex variability of the underground rock mass, so that the applicability of the method needs to be further verified. The methods are all directed at the study of single parameter characteristics, the mutual influence among tunnel millisecond blasting parameters, the superposition of the differential time, the single-hole explosive quantity, the blasting hole number and the vibration speed has a complex coupling relation, and no study exists on a design method considering the multi-parameter mutual influence.
Some researchers have calculated the synthesis of the differential blasting vibration based on the single-hole vibration waveform of the field blasting, and then the method for designing the blasting parameters is carried out, but the delay error of the common detonator is large, some research documents actually measure the delay range of the sample detonator before the blasting, calculate the possible synthesis vibration combination in the differential delay range according to the single-hole vibration data, and design the dosage according to the most unfavorable condition, but because the section delay is fixed, the delay time can not be designed actually; and the lowest value of the dosage in all possible delays can only be taken to ensure safety when the dosage is calculated, and the method is not suitable for accurate control blasting of the digital detonator.
Disclosure of Invention
The invention discloses a tunnel blasting parameter design method based on digital electronic detonator detonation, which aims to solve any one of the above and other potential problems in the prior art.
In order to solve the problems, the technical scheme of the invention is as follows: a tunnel blasting parameter design method based on digital electronic detonator detonation designs blasting parameters based on the characteristics of digital electronic detonators on the premise of realizing vibration control, gives full play to the performance advantages of the digital electronic detonators, and simultaneously realizes efficient footage, and comprises the following steps:
(1) determining the maximum single-hole loading amount of the cut blasting, the number of the cut hole blasting holes and the optimal differential time, wherein the method comprises the following steps:
firstly, giving a safety vibration speed standard VstanOn the basis, a possible value (…, C) of the maximum single-hole loading of the cut hole is obtained through an empirical formulaj-1，Cj，Cj+1…), all possible values of the number of slotted blastholes (N) are determined on the basis of the size of the section and experience1，N2，…)。
Secondly, performing a single-hole single-free-face blasting experiment on the tunnel site and fitting a vibration curve of the single-hole single-free-face blasting experiment.
Actually measuring single-free-surface single-hole vibration waveforms with different dosages on a tunnel site, and fitting each single-hole waveform based on Fourier series to obtain a fitting function f (x) for convenient superposition calculation, wherein the function form is as follows:
wherein f (t) is a single-hole waveform fitting function; t is time; a is0、ai、biFourier fitting coefficients are obtained; omega is fundamental frequency; k is a Fourier fitting series.
Fourier fitting coefficient a0、ai、biAnd the fundamental frequency ω is calculated as follows:
in the formula: t is waveform truncation time; m is the total sampling point number; y ismIs the mth sample value.
And thirdly, selecting a combination of single-hole explosive quantity and the number of the blast holes in the cut hole, and in the blast holes of the same type, such as the cut hole and the auxiliary hole, utilizing MATLAB programming, and respectively and successively carrying out differential blasting vibration synthesis calculation on f (x) and f (x) by taking 1ms as an increment and from 1 to 50ms to obtain a calculated and synthesized vibration curve.
When the urban shallow tunnel is blasted, the vibration speed in the vertical direction is usually far higher than that in other directions, and the corresponding synthetic vibration speed is obtained by carrying out linear superposition calculation on the vertical vibration speed according to different detonation times.
The dosage of each cut hole is the same, the distance between blast holes of the cut holes is negligible compared with the distance from an explosion source to a ground surface measuring point, and the vibration waveforms of the N cut holes are considered to be the same. The principle of superposition is as follows:
Δtn＝(n-1)Δt
in the formula, V (t, { Δ t)nV (t) is a time global waveform fitting function, Δ t is a selected inter-well differential time, the inter-well differential time takes the same value, Δ tnThe detonation time of the nth cut hole.
Fourthly, under a certain combination of the dosage and the number of the blast holes of the cut holes, when the calculated delta t takes different values, the holes are successively exploded to form the maximum vibration speed by superposition.
When Δ t is 1ms, the superimposed composite waveform function V (t, {0,1,2 … }) has a maximum vibration velocity Vmax(t, {0,1,2 … }) and a maximum vibration velocity V exists in the superimposed composite waveform function V (t, {0,2,4 … }) when Δ t is 2msmax(t, {0,2,4 … }). Comparing all the maximum vibration speeds to obtain the minimum value V of all the maximum vibration speed valuesmin. Namely:
Vmin＝{Vmax(t,{0,Δt,2Δt…})}min
in the formula, VminThe corresponding differential time delta t is the optimal differential time corresponding to the combination of the dosage and the number of the cut hole blasting holes.
The optimal differential time is a parameter specially defined for convenient blasting design, and means that after different inter-hole delay synthetic vibration velocity curves are obtained through calculation, the maximum synthetic vibration velocity values of the curves are compared, wherein the inter-hole differential corresponding to the minimum value is called the optimal differential time.
Considering different combinations of the dosage and the number of blast holes of the cut hole, and selecting the most appropriate blasting parameters through the maximum vibration velocity synthesis calculation.
For any combination of the dosage and the number of the cut hole blasting holes, the minimum value of the maximum synthetic vibration velocity and the corresponding optimal differential time can be obtained through the operation. Traversing all combinations of the dosage and the number of the blast holes of the cut holes by adopting an enumeration method, and repeating the calculation of the third step and the fourth stepThe process obtains the optimal differential time and the corresponding V under all the combinations of the dosage and the number of the blast holes of the cut holemin. All combined VminAnd a safe vibration velocity VstanComparing, selecting to satisfy VminThe maximum single-hole medicine quantity smaller than the safe vibration speed is the maximum single-hole medicine quantity of the cut hole. When the maximum single-hole dosage is determined, selecting VminAnd carrying out blasting design on the number of the blast holes of the cut holes and the optimal differential time corresponding to the minimum value.
In rare cases, e.g. Vmin＝VstanWhen, for safety reasons, a slightly smaller V is selectedminAnd carrying out blasting design according to the corresponding blasting parameters.
(2) Determination of time delay between cut hole and auxiliary hole
Method for determining second free face forming time
How to accurately utilize the vibration reduction characteristic of the second free surface is a problem to be solved by design, and the key point is to obtain accurate quantification time formed by the second free surface. The influence of the second free face on the vibration speed after the second free face is formed is not considered in the porous micro-difference blasting vibration calculation synthetic vibration curve, the blasting vibration curve including the second free face effect is obtained through field actual measurement, the two curves are compared on the same graph, and the starting point of the actual measurement vibration speed peak value which is reduced by more than 50% compared with the calculation synthetic vibration speed peak value at the same moment is the second free face forming time TSF。
② determination of time delay between cut hole and auxiliary hole
The second free face forming time T is determinedSFThen, the delay time between the cut hole and the auxiliary hole can be determined according to the time. In order to fully utilize the damping effect of the second free surface, the auxiliary hole needs to be detonated after the second free surface is formed:
ΔD＞TSF-(N1-1)×Δt
in the formula: delta D is a micro-difference interval between a final hole of the cut and a first hole of the auxiliary cut; t isSFForming time for the second blank surface; n is a radical of1The number of the cut holes is; and delta t is the time of the micro difference between the adjacent holes of the cut hole and the adjacent holes of the auxiliary cut.
The value of the differential interval delta D between the final hole of the plunge cut and the first hole of the auxiliary plunge cut is generally less than 100 ms. (3) Method for determining time and dosage of auxiliary hole-to-hole differential
The second temporary empty surface is formed early during auxiliary hole blasting, the blasting efficiency and the vibration reduction effect are improved, the dosage can be reduced by 15-20% compared with that of a slotted hole, and therefore, how to determine the time delay between holes is very important. In view of the extremely complex action of the vibration wave and the free surface and the difficulty in solving the vibration speed variation value, a semi-quantitative method can be adopted for solving the problems: calculating to obtain the optimal inter-hole differential time delta t according to the method before the second blank surface is formed1(ii) a After the second free surface is formed, carrying out field experiments by using different inter-hole differential time (arbitrarily taking values within 1-50 ms), and if delta t is used1If the actually measured vibration peak value of the time delay time between holes is still smaller than other time delay vibration speeds, the delta t can be taken1To design the time difference.
Compared with the existing tunnel blasting parameter design method, the method has the following characteristics:
1) at present, blasting parameter design based on digital electronic detonator detonation mostly adopts a common blasting design method, if the dosage calculation is mainly obtained by inverse calculation of a Sagnac formula, the error is large; the inter-pore differential time often depends on engineering experience and lacks theoretical calculation support. The invention provides a system and a digital electronic detonator blasting design method with rigorous theoretical support, which is beneficial to fully exerting the potential of the digital electronic detonator.
2) By comprehensively considering the complex coupling relation of blasting parameters such as differential time, single-hole explosive quantity, blasting hole number and synthetic vibration speed and the like, the blasting parameters such as the maximum single-hole explosive quantity, the number of cut hole blasting holes and time delay among holes based on digital electronic detonator detonation are calculated and designed, the tunneling speed under the safe vibration speed can be improved to the maximum extent, meanwhile, the vibration speed is reduced, the efficient tunneling is realized, the blasting efficiency is improved, the construction period is shortened, and the economic benefit is improved.
3) The forming time of the second free face is accurately calibrated, the optimal delay time between the cut hole and the auxiliary hole is determined, the vibration reduction effect of the second free face is effectively utilized, and the peak value of the blasting vibration velocity is greatly reduced.
4) Compared with the non-electric detonator, the invention adopts the digital electronic detonator to detonate hole by hole, the precision of time delay between holes is higher, the low vibration speed accurate control blasting is realized, and the blasting efficiency is improved.
Drawings
Fig. 1 is a diagram showing arrangement and initiation sequence of blasting hole sites on a tunnel upper step.
FIG. 2 is a waveform of a single-hole single-free-surface vibration measured on site.
FIG. 3 is a comparison of a single-hole waveform fitting curve with a measured curve.
Fig. 4 shows the optimal differential time for different numbers of cut holes for each dose.
Fig. 5 shows the maximum synthetic vibration velocity of different cut hole numbers under each dosage.
FIG. 6 is a graph of the peak vibration of 8-hole differential blasting at different differential intervals (1.4kg dose).
FIG. 7 is a graph comparing a calculated composite vibration curve to an actual measured vibration curve.
Fig. 8 shows the resultant peak vibration velocity variation with different delays between the cut hole and the auxiliary cut.
FIG. 9 is a comparison of the calculated and measured vibration speeds for 50ms delay between the cut hole and the auxiliary cut.
FIG. 10 is a graph of the peak of differential blasting vibration for 8 wells at different differential intervals (1.0kg dose).
FIG. 11 is a schematic diagram of the arrangement of auxiliary wells and the differential time between wells.
Fig. 12 is a graph comparing the change of the vibration velocity at different time delays of the auxiliary eye.
Fig. 13 is a flow chart of a blasting parameter design method of the invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to specific embodiments and accompanying drawings.
As shown in fig. 13, the method for designing tunnel blasting parameters based on initiation of digital electronic detonators of the present invention specifically includes the following steps:
s1) obtaining single-hole blasting vibration curves with different dosages by field actual measurement, fitting, and calculating the cut holes one by oneDetermining the maximum single-hole loading capacity, the number of the blasting holes of the cut hole and the optimal differential time delta t after comparing the composite vibration velocity of superposition of different combinations according to the differential composite vibration curves of various parameters of the maximum single-hole loading capacity, the number of the blasting holes of the cut hole and the differential time1；
S2) designing and determining the field experiment of the second empty face forming time according to the characteristics of the digital electronic detonator to obtain more accurate forming time TSF(ii) a Designing delay time between the final hole of the cut and the initial hole of the auxiliary cut by using the vibration reduction effect of the second free face;
s3) adopting a semi-quantitative method to obtain the optimal differential time among auxiliary holes and the maximum single-hole loading.
The S1) comprises the following specific steps:
s1.1) setting a safety vibration speed standard VstanOn the basis, the value range { C of the maximum single-hole loading amount of the cut hole is obtained through the Sa's formulajAnd determining the value range of the number of the blast holes of the cut hole according to the section size { N }i}；
S1.2) actually measuring the single-hole maximum loading value range { C) of all cut holes determined according to S1.1) in the field of tunneljFitting single-hole waveforms of various doses based on Fourier series to obtain a fitting function f (x) by calculation;
s1.3) selecting the value range of the single-hole maximum loading of the cut hole determined in S1.1) { CjAnd the number of blast holes of the cut hole { N }iRandomly combining, and selecting the single-hole maximum dosage C of one cut holejAnd the number N of blast holes of the cut holeiThe fit function f (x) is subjected to function superposition calculation successively by taking the inter-hole differential delta t as 1-50 ms and taking 1ms as increment, and a porous differential blasting calculation synthetic vibration curve of the combination at different differential time is obtained;
s1.4) maximum amount of single-hole medication C for cutting holes from S1.3)jAnd the number N of blast holes of the undercut holeiUnder the combination of (3), after calculating to obtain the time-delay synthesis vibration velocity curve among different holes, the maximum synthesis vibration velocity value of the time-delay synthesis vibration velocity curve among different holes is calculatedLine comparison is carried out, and the minimum value V is selectedminSaid minimum value VminThe corresponding inter-hole differential time is the optimal differential time under the combination of the single-hole maximum dosage of the cut hole and the number of blast holes of the cut hole;
s1.5) traversing the maximum single-hole medicine amount C of the cut hole by adopting an enumeration methodjAnd the number N of blast holes of the undercut holeiRepeating S1.3) and S1.4) to obtain the maximum dosage C of all cut holes in one holejAnd the number N of blast holes of the undercut holeiMinimum value V of maximum combined vibration velocity values under combinationminAnd the corresponding optimal differential time, and the minimum value V in the maximum combined vibration velocity values of all the combinationsminWith safe vibration speed standard VstanComparing, selecting the minimum value VminLess than safety vibration speed standard VstanMinimum value of (V)minThe maximum value of the corresponding single-hole medicine quantity is the maximum single-hole medicine quantity of the designed cut hole;
according to the number of blast holes of the cut hole and the optimal differential time which are determined to correspond to the maximum single-hole dosage of the designed cut hole, the number of blast holes of the designed cut hole and the optimal differential time delta t are determined1。
The S2) concrete steps are:
s2.1) comparing the calculated composite vibration curve of the porous micro-difference blasting obtained in the S1.3) with the actually measured blasting vibration curve which is actually measured on site and contains the effect of the second face, and taking the starting point, at which the actually measured vibration velocity peak value of the actually measured blasting vibration curve at the same moment is reduced by more than 50% compared with the vibration velocity peak value of the calculated composite vibration curve, as the forming time T of the second faceSF；
S2.2) obtaining a second temporary empty face forming time T according to S2.1)SFDetermining the time delay between the cut hole and the auxiliary hole, and detonating after the second free surface is formed according to the requirement of the auxiliary hole, so that the detonation time of the auxiliary cut first explosion hole is longer than the second free surface forming time TSF(the delay time between auxiliary holes is generally less than 100 ms).
The S3) comprises the following specific steps:
s3.1) obtaining the optimum differential time delta t of the cut hole obtained in S1.5)1And carrying out on-site auxiliary hole blasting vibration comparison experiments with other different inter-hole differential time ((arbitrarily taking value within 1-50 ms)) for verification, wherein if the optimum differential time delta t of the cut hole is less than or equal to1The minimum value of the actually measured vibration peak value of the time delay time among the holes is the optimal differential time delta t of the cut hole1Auxiliary well differential time;
s3.2) determining the single-hole dosage of the auxiliary hole: the dosage of the auxiliary hole single hole is reduced by 15-20% compared with the maximum dosage of the cut hole single hole.
A tunnel blasting parameter design method based on digital electronic detonator detonation is suitable for tunnel blasting with high requirements on safe vibration speed control.
Example (b):
the invention relates to a tunnel blasting parameter design method based on digital electronic detonator detonation, which is explained in detail according to a specific engineering example, but the invention is not limited to specific implementation cases.
The engineering supported by the invention is a tunnel engineering of a north avenue of a Guanyin bridge in Chongqing city, the engineering site is located in a central urban area of Chongqing city, dense ground buildings and underground pipelines are arranged in a construction area, and the tunnel is buried deep by 20-30 m and belongs to a shallow tunnel. The blasting area is mainly gray and grey-white sandstone without unfavorable geological phenomena, and the tunnel surrounding rock category is IV grade. According to the requirements of owners, the ground surface vibration speed does not exceed 1.0cm/s by referring to blasting safety regulations (GB6722-2014) and similar construction experience. The construction is carried out in a traditional tunnel blasting excavation mode, the footage is extremely short, the blasting circulation is increased, the construction organization is complex, the progress is slow, and the economic benefit is low.
The blasting test is carried out in a section K1+ 330-K1 +367 of the left tunnel hole of the tunnel, the section of the tunnel is 11.8m multiplied by 9.55m, and the area of the tunnel is 90.85m2. The digital electronic detonators are adopted to carry out hole-by-hole differential detonation (the precision of the digital electronic detonators used in the test is +/-1 ms), and the full-section blasting is carried out once forming. According to the field condition and the height of the drilling platform, the arrangement of blast holes and the design of the initiation sequence are shown in figure 1, and the blasting parameters are determined according to the research.
The invention adopts the digital electronic detonator to realize the accurate control construction of tunnel blasting in a complex environment. According to the characteristics of the digital electronic detonator, blasting parameters such as the maximum single-hole loading quantity, the number of blasting holes, the optimal differential time, the second free face forming time, the delay time between the underholing hole and the auxiliary hole, the differential time between the auxiliary holes, the quantity of the blasting powder and the like are determined.
(1) Determining the maximum single-hole loading quantity of the cut holes, the number of blast holes of the cut holes and the optimal differential time
Firstly, a tunnel field single-hole single-free surface blasting experiment and vibration curve fitting are carried out.
A single-hole single-free-face blasting test with 3 doses (1.0kg, 1.2kg and 1.4kg) is carried out in a tunnel with a left hole of the kwan-yin bridge, and the ground surface right above the tunnel face is monitored (the measured vibration speed is maximum) to obtain a corresponding vibration oscillogram. Each dosage is tested for more than 3 times, and the waveforms of the same dosage are basically consistent under the same condition by comparing the results of multiple single-hole single-free tests. A typical single well waveform for each dose is shown in figure 2. The vibration peak values of 1.0kg, 1.2kg and 1.4kg of single-hole vibration are 0.366cm/s, 0.512cm/s and 0.897cm/s in sequence.
The single-hole waveform is truncated before fitting. As shown in fig. 2, the vibration velocity after 110ms has almost decayed to 0, but to ensure that the individual waveforms are sufficiently superimposed, the single-hole waveform is truncated at 140 ms.
And (3) calculating a fitting function f (t) by using MATLAB software programming based on the formula (1) and the calculation formula of each parameter. The value of the fitting series k in the formula (1) is adjusted according to the waveform fitting precision, and the curve fitting precision of different series is shown in table 1 by taking 1.4kg of medicine as an example. And as the fitting series number is increased, the fitting precision is increased, when k takes the value of 32, the fitting precision reaches 0.997, and the k value is determined to be 32.
TABLE 1 comparison table of fitting series k and fitting accuracy
Wherein, the fitting and the measured waveform of 1.4kg are shown in figure 3, the standard deviation of curve fitting is 0.0054, the correlation coefficient is 0.997, the fitting is good, and the measured curve and the fitted curve are almost completely overlapped.
Extending the fitting waveform function f (t) to the time universe to obtain a final single-hole waveform function formula v (t) as follows:
wherein v (t) is a time global waveform fitting function; t is time.
Secondly, using MATLAB programming to perform vibration superposition calculation on f (x) according to different combinations of dosage, the number of the slotted holes and the differential time to obtain a calculated and synthesized vibration curve;
on the basis of a single-hole waveform fitting function V (t) of each dosage, an MATLAB program is utilized to calculate N-hole superposition synthetic vibration velocity V (t, delta t) of 1.0kg, 1.2kg and 1.4kg dosages respectively, the number N of the slotted hole blasting holes is 2-20, the same value delta t is taken for the inter-hole differential time, and the value range of adjacent hole differential is 1-50 ms. The superposition calculation function is as follows:
wherein V (t, Δ t) is an N-hole vibration superposition function, and V (t) is a time global waveform fitting function; delta t is the differential time between adjacent holes, and takes the values of 1ms, 2ms,. cndot.. cndot., 50 ms; t is the waveform truncation time, 140 ms.
Determining maximum single-hole loading quantity, cut hole blasting hole number and optimum differential time
The MATLAB program is used for calculating to obtain the optimal differential time of 1.0kg, 1.2kg and 1.4kg under different numbers of the cut holes and the corresponding maximum synthetic vibration speed, the optimal differential time has a plurality of time periods (see below), and only the calculation results of the differential time of each dosage within 1-10 ms are listed in space limited, as shown in figures 4 and 5.
According to the figure, under the dosage of 1.0kg and 1.2kg, the maximum synthetic vibration speed of the number of the cut holes is not more than 0.449cm/s and 0.570cm/s, both are far less than the safe vibration speed of 1.0cm/s, under the dosage of 1.4kg, the maximum synthetic vibration speed is 0.9cm/s and is less than the safe vibration speed when the number of the cut holes is 2, 3, 8, 9 and 11 and is more than 16; according to the size of the tunnel excavation section, the number of the cut holes is preferably less than 10, and the number of the wedge-shaped cut holes is even. The maximum single-hole dosage is determined to be 1.4kg, and the number of the cut holes is 8.
As shown in fig. 6, the maximum synthetic vibration velocity of 8-hole cut under the variation of the adjacent hole differential time of 1-50 ms for the 1.4kg dose is shown, the optimal differential time in which the synthetic vibration velocity meets the safety index of 1.0cm/s in the figure has 5 time differences (marked in the green interval in the figure), and the maximum vibration value in the green zone is mostly not more than the single-hole blasting vibration peak value in fig. 2; the smaller the differential time is under the condition that the vibration speed is not over standard, the better the blasting synergistic effect is, so the differential time can be 4-5 ms at intervals, and 5ms is selected as the delay time.
(2) Determination of time delay between cut hole and auxiliary hole
Determining the second free face forming time
To determine the time for the formation of the second free face, a blasting test was carried out in situ, designing an 8-hole undercut according to fig. 1. In order to avoid the exceeding of the vibration speed of the primary explosion hole, the dosage of the 1 st primary explosion hole is 1.2kg, and the dosages of the other 7 holes are 1.4 kg. Because the formation of the second free face by the hole-by-hole cutting section may require longer initiation time, and the initiation at smaller intervals can more accurately determine the formation time, a contradiction exists between the two, and in order to take both factors into account, the initiation time difference between adjacent holes of the cutting is set to be 8 ms. The burst vibration curve was measured directly above the tunnel as shown in fig. 7 (black curve).
By using the formula (4) and the MATLAB program, on the basis of the single-hole test vibration data, a hole-by-hole slitting vibration synthesis curve with the inter-hole delay of 8ms is calculated and obtained, as shown in fig. 7 (red curve).
Comparing the curves in the graph, wherein the actual measurement of the detonation time of each hole of the digital electronic detonator is basically consistent with the design time; the difference between the vibration peak value of the first 5-hole differential blasting vibration curve and the calculated vibration curve is very small, which indicates that the second free surface does not influence the vibration speed; however, the vibration velocity values of the two curves in the dashed line frame are significantly different, and the actual peak vibration velocities K7 and K8 from the K6 and K6 ' starting from 48ms to the 7 th and 8 th holes after explosion are reduced by more than 50% compared with the calculated values K7 ' and K8 ', so that the second critical empty surface causing the vibration velocity to be significantly changed is judged to be formed between 41 and 48 ms.
② determination of time delay between cut hole and auxiliary hole
And on the premise that the single-hole explosive quantity is 1.4kg and the inter-hole detonation interval is 5ms, calculating the synthetic vibration velocity values of different delays between the cut hole and the auxiliary hole to determine the optimal time difference.
Designing 8 cut hole holes and 6 auxiliary holes according to the figure 1, and participating in calculating 14 blast holes; calculating the variation condition of the differential synthetic vibration velocity between the final blasting hole of the cut hole and the auxiliary initial blasting hole according to the time delay of 5 ms-50 ms. The calculation formula is as follows:
ΔD＝K×Δt K＝1,2,……,10
in the formula: v (t, Δ D) F (t, Δ t)i) Is a synthesized waveform function; n is a radical of1The number of the cut holes is 8; n is a radical of2The number of the auxiliary holes is 6; delta t is the differential time between adjacent holes of the cut hole and adjacent holes of the auxiliary cut, and is 5 ms; delta D is a micro-difference interval between a final hole of the cut and a first hole of the auxiliary cut; k is a proportionality coefficient, and K is delta D/delta t.
As shown in fig. 8, for the correspondence between the different delay time difference Δ D between the cut hole and the auxiliary cut obtained by the calculation using the MATLAB program and the maximum peak vibration speed, the delay time between holes of the same kind is set to 5ms, wherein the maximum value of the positive and negative vibration peaks is taken at the same time difference. The peak vibration velocity is smallest at a time difference of 5ms between the undercut hole and the auxiliary undercut in the figure, which corresponds to 40ms after detonation (since the final hole detonation time for the undercut hole is 35 ms). The second face empty surface is known to be formed 48 ms-50 ms after the detonation, so the second face empty surface is not formed at the moment; the second free surface forming time corresponds to the time delay of 15ms between the cut hole and the auxiliary cut hole in fig. 8, that is, if the time delay between the two types of holes is greater than 15ms during design parameters, the vibration reduction effect of the second free surface can be ensured.
Further analysis shows that the synthetic vibration speed in all the time periods of more than deltad 15ms exceeds 1.0cm/s safe vibration speed, but does not exceed 1.24cm/s at most. However, considering the strong vibration reduction effect of the second free face, the peak vibration speed in these periods will not exceed the safety index, and the calculated composite vibration speed value is lower when the optimal delay time interval Δ D is 35ms, i.e. 70ms after detonation.
In order to verify the correctness of the method, the field test does not select 35ms delay, but selects 50ms delay time difference with larger peak vibration velocity. As shown in fig. 9, when Δ D is 50ms, the measured vibration curve is compared with the calculated differential vibration synthesis curve, and it is found that the full-stroke vibration speed does not exceed the standard.
(3) Method for determining time and dosage of auxiliary hole-to-hole differential
The second free face is formed early during auxiliary hole blasting, the blasting efficiency and the vibration reduction effect are improved, the dosage can be reduced by 15-20% compared with the slotted hole, and the dosage of the auxiliary hole is 1.0 kg; firstly, theoretical calculation is carried out before the second free surface is formed, as shown in fig. 10, the peak value of the vibration speed of the full time course of the dosage of 1.0kg is obtained, analysis shows that the optimal interpore differential time is 5ms, and further field experiments are needed to verify whether the 5ms is the optimal interpore delay.
As shown in fig. 11, different delay blasting field tests are performed in the auxiliary eye area (2) in the middle of the tunnel, and the blasting vibration velocity change is analyzed when the delay is 3ms, 5ms and 8ms respectively. In order to keep the conditions of the face to the empty are consistent, 1 row and 2 rows of delay vibration speeds are designed for comparing 8ms and 5 ms; 3. 4 rows compare the delayed vibration speed of 3ms and 5 ms; the corresponding delay period vibration waveform is shown in fig. 12.
As can be seen from FIG. 12, the maximum vibration velocity was 0.79cm/s for 1 row (8ms) and 0.73cm/s for 2 rows (5 ms); the maximum vibration velocity of 3 rows (3ms) was 0.93cm/s, and the maximum vibration velocity of 4 rows (5ms) was 0.75 cm/s. Comparing the vibration waveforms of the 1 row and the 2 rows, wherein the 5ms delay maximum vibration speed is less than 8ms, and the vibration speed is reduced by 7.6%; comparing 3 rows and 4 rows of vibration waveforms, 5ms delay is less than 3ms maximum vibration speed, and the vibration speed reduction ratio is 24.1%. The 5ms delay vibration reduction effect is better than that of 3ms and 8 ms. Therefore, through comparison and analysis of field test results, after the second free surface is formed, the synthetic vibration speed of different delays is still consistent with the difference characteristics before formation, and the auxiliary inter-eye delay parameters can be designed by using a synthetic vibration speed calculation method.
(4) Application of the invention in tunnel blasting engineering of big roads in north of Guanyin bridge
The method is successfully applied to blasting excavation of tunnels in the big roads in the north of Guanyin bridge, blasting vibration test is carried out on the earth surface right above the blasting section during each blasting, and the monitoring result shows that all vibration speeds are less than 1.0cm/s, so that the vibration speed control requirement is met; under the condition of meeting the requirement of vibration speed control, the blasting footage is increased to the maximum extent, the blasting efficiency is improved, the construction period is shortened, and the high-efficiency tunneling is realized. A new way is opened up for the design of tunnel blasting parameters based on the initiation of digital electronic detonators under the requirement of low vibration speed.
The invention relates to a tunnel blasting parameter design method based on digital electronic detonator detonation, which is mainly characterized in that:
core blasting parameters such as maximum single-hole loading capacity, the number of blast holes of cut holes, optimal inter-hole differential time and the like are determined through calculation; accurately calibrating the forming time of the second free face, and designing the delay time between the cut hole and the auxiliary hole by utilizing the forming time; blasting parameters such as time delay between auxiliary holes, explosive quantity and the like are designed by adopting a semi-quantitative method. The circulating footage is increased, the blasting vibration speed is reduced, the construction period is shortened, the tunneling efficiency is improved, and the safety and economic benefits are remarkable.
The above is an embodiment of the present invention, and according to the above-listed several main features, all of them are regarded as the same type of the present invention.
The above description is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, several modifications and variations can be made without departing from the technical principle of the present invention, and these modifications and variations should also be regarded as the protection scope of the present invention.
Claims (2)
1. A tunnel blasting parameter design method based on digital electronic detonator initiation is characterized by comprising the following steps:
s1) obtaining single-hole blasting vibration curves with different dosages through field actual measurement, fitting, and calculating the maximum single-hole dosages of the cut holes, the number of the blasting holes of the cut holes and the differential blasting multi-hole under different combinations of various parameters of differential time one by oneSynthesizing a vibration curve, comparing the superposed synthetic vibration speeds of different combinations, and determining the maximum single-hole loading of the designed cut holes, the number of blasting holes of the cut holes and the optimal differential time
1The method comprises the following specific steps:
s1.1) at a given safe vibration speed standard
On the basis, the value range { C of the maximum single-hole loading amount of the cut hole is obtained through the Sa's formulajDetermining the numerical range of the blasting holes of the cut hole according to the section sizeN i }；
S1.2) actually measuring the single-hole maximum loading value range { C) of all cut holes determined according to S1.1) in the field of tunneljThe single-free-surface single-hole vibration waveform of each dose is fitted based on Fourier series, and a fitting function is obtained through calculation
；
S1.3) selecting the value range of the single-hole maximum loading of the cut hole determined in S1.1) { CjGreat moment and number of blast holes of a slotted holeN i Randomly combining, and selecting the single-hole maximum dosage C of one cut holejAnd the number of blast holes of the cut holeN i In combination with a pore-to-pore differential
，
1-50 ms, and fitting the function successively in increments of 1ms
Performing function superposition calculation to obtain the combination at different microCalculating a composite vibration curve by the porous differential blasting of the differential time;
s1.4) according to the maximum single-hole dosage C of all cut holes in S1.3)jAnd the number of blast holes of the cut holeN i After the time-delay synthetic vibration velocity curve among different holes is obtained through calculation, the maximum synthetic vibration velocity values of the time-delay synthetic vibration velocity curve among different holes are compared, and the minimum value is selected
Said minimum value
The corresponding inter-hole differential time is the optimal differential time under the combination of the single-hole maximum dosage of the cut hole and the number of blasting holes of the cut hole;
s1.5) traversing the maximum dosage C of a single hole of a cut hole by adopting an enumeration methodjAnd the number of blast holes of the cut holeN i Repeating S1.3) and S1.4) to obtain the maximum dosage C of all cut holes in one holejAnd the number of blast holes of the cut holeN i Minimum value of maximum combined vibration velocity values in combination
And the corresponding optimal differential time, and the minimum value of the maximum combined vibration velocity values of all the combinations
And safe vibration velocity standard
Comparing, selecting the minimum value
Less than the safe vibration speed standard
Minimum value of (2)
The maximum value of the corresponding single-hole medicine quantity is the maximum single-hole medicine quantity of the designed cut hole;
according to the number of blast holes of the cut holes and the optimal differential time corresponding to the maximum single-hole dosage of the designed cut holes, the number of blast holes of the designed cut holes and the optimal differential time are determined
1；
S2) designing and determining the second temporary empty surface forming time according to the characteristics of the digital electronic detonator, and obtaining the second temporary empty surface forming time
(ii) a And designing the delay time between the last hole of the cut hole and the first hole of the auxiliary hole by utilizing the vibration reduction effect of the second free surface, and the method specifically comprises the following steps:
s2.1) comparing the calculated composite vibration curve of the porous micro-difference blasting obtained in the S1.3) with the actually measured blasting vibration curve which is actually measured on site and contains the effect of the second face, and taking the starting point, at which the actually measured vibration velocity peak value of the actually measured blasting vibration curve at the same moment is reduced by more than 50% compared with the vibration velocity peak value of the calculated composite vibration curve, as the forming time of the second face
；
S2.2) second face-to-face-space formation time obtained according to S2.1)
Determining the time delay between the cut hole and the auxiliary hole, and detonating after the second free surface is formed according to the requirement of the auxiliary hole, so that the detonation time of the first detonation hole of the auxiliary hole is longer than the formation time of the second free surface
；
S3) obtaining the optimal differential time between auxiliary holes and the maximum single-hole loading by adopting a semi-quantitative method, and the specific steps are as follows:
s3.1) obtaining the optimum differential time of the cut hole obtained in S1.5)
1And carrying out on-site auxiliary hole blasting vibration contrast experiments for verification compared with other different hole differential time, and if the optimum differential time of the cut hole is obtained
1The minimum value of the actually measured vibration peak value of the time delay time among the holes is the optimal differential time of the cut holes
1The optimal differential time between the auxiliary holes is obtained;
s3.2) determining the maximum loading of the auxiliary hole single hole: the maximum single-hole drug loading of the auxiliary holes is reduced by 15-20% compared with the maximum single-hole drug loading of the cut holes.
2. The method according to claim 1, which is suitable for tunnel blasting with high requirements on safe vibration velocity control.
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