Blasting design method considering cumulative damage effect

Abstract

The invention discloses a blasting design method considering a cumulative damage effect. The blasting design method comprises the following steps: (1) carrying out regression fitting on a blasting seismic wave attenuation law based on a Sadgowski formula; (2) damage judgment is conducted on the blasted and excavated bench needing to consider the cumulative damage effect and the reserved rock mass of the current blasted and excavated bench; (3) constructing a damage prediction model of the blasted and excavated bench; (4) performing regression fitting to obtain an exponential function curve of the damage depth and the mass point peak vibration velocity under each explosion center distance; and (5) during blasting design, obtaining an exponential function curve of the damage depth corresponding to the field blasting center distance and the mass point peak vibration speed, taking the corresponding mass point peak vibration speed when the damage depth is the maximum damage depth, substituting the mass point peak vibration speed into a blasting seismic wave attenuation law, calculating the maximum single-shot explosive quantity, and calculating the blasting seismic wave attenuation law according to the maximum single-shot explosive quantity. And optimizing the blasting design based on the maximum single-shot explosive quantity. By means of blasting designed through the method, the stability and safety of the side slope can be guaranteed.

Description

Technical Field

[0001] The present application relates to blasting technology in the field of water conservancy and civil engineering, and in particular to a blasting design method that takes cumulative damage effects into consideration. Background Art

[0002] With the rapid development of my country's economy, a large number of large-scale water conservancy and hydropower projects are being built in the mountainous areas of the southwest and northwest, all of which are faced with the difficult problem of controlling the excavation of high rock slopes under complex conditions. Blasting is the main means of excavating high rock slopes. The blasting excavation of hydraulic rock high slopes should not only achieve the ideal degree of rock crushing in the excavation area, but also reduce the disturbance of blasting to the reserved rock mass. Frequent blasting load disturbances will cause the original cracks in the rock mass to be activated, expanded and penetrated, resulting in fatigue damage accumulation, which will lead to the deterioration of the macroscopic mechanical properties of the rock mass, and even failure or destruction.

[0003] In actual engineering, high slope blasting and excavation operations involve multiple steps and multiple blasting and excavation. The single excavation and blasting of tens of thousands of cubic meters of rock mass is frequent, which increases the disturbance intensity of the blasting load. The dynamic action range induced by frequent blasting disturbances is much larger than its excavation range, which is an important inducement for the cumulative damage effect and even instability of high slopes during the construction period. Reasonable blasting design is particularly important. The blasting design method is based on the peak velocity of the particle point in the near area of ​​blasting, and the blasting vibration waveform reflects the damage range. In order to strictly control the depth of retained rock damage, the cumulative damage effect leads to a reduction in the safety standard of blasting vibration. However, the current safety control standard for blasting vibration of rock high slopes only takes the damage range of the retained rock mass in the current step as the object, and has not yet considered the impact of the cumulative damage effect.

[0004] In order to ensure slope stability and safety control, the cumulative damage effect caused by multiple blasting and excavation on high slopes with multiple steps must be considered, and a reasonable blasting design method should be established based on this. Summary of the invention

[0005] In view of the fact that the existing high-slope deep-hole step blasting design method does not take into account the cumulative damage effect caused by multiple blastings at multiple steps, this application proposes a blasting design method that takes into account the cumulative damage effect.

[0006] This application provides a blasting design method considering cumulative damage effects, including:

[0007] (1) Using multiple sets of on-site blasting vibration monitoring data, regression fitting is performed on the blasting seismic wave attenuation law based on the Sadovsky formula;

[0008] (2) Using multiple sets of rock mass longitudinal wave velocity test data before and after the blasting test, the damage of the blasted excavation steps and the retained rock mass of the current blasting excavation steps that need to consider the cumulative damage effect is determined, and the damage variables of each step at different damage depths are calculated respectively;

[0009] (3) According to step (2), the cumulative damage variables of the blasted excavation steps at each damage depth after each blasting test are obtained, and the cumulative damage variables corresponding to each blasting number at different damage depths are further obtained. The data of the damage depth and the cumulative damage variables at each blasting number are respectively fitted to obtain a damage prediction model for the blasted excavation steps;

[0010] (4) Multiple blasting tests were carried out at different blasting center distances. The peak vibration velocity of the particle point in each blasting test was calculated using the attenuation law of blasting seismic waves, and the damage depth of the step blasting slope was measured. The exponential function curve of the damage depth and the peak vibration velocity of the particle point at each blasting center distance was obtained through regression fitting.

[0011] (5) When designing blasting, obtain the exponential function curve of the damage depth and the peak vibration velocity of the particle corresponding to the distance from the explosion center on site, take the peak vibration velocity of the particle corresponding to the maximum damage depth, bring the peak vibration velocity of the particle into the attenuation law of the blasting seismic wave, calculate the maximum single-shot charge, and optimize the blasting design based on the maximum single-shot charge;

[0012] The maximum damage depth is determined by determining the number of blasting times and the damage variable threshold, and obtaining the damage depth corresponding to the determined number of blasting times and the damage variable threshold from the damage prediction model, that is, the maximum damage depth.

[0013] Furthermore, step (1) is specifically as follows: transforming the Sadovsky formula into a linear formula y=αx+b, performing regression fitting on the linear formula using multiple sets of on-site blasting vibration monitoring data, solving for coefficients α and b, and obtaining the blasting seismic wave attenuation law;

[0014] Among them, y = lgv, b = lgK, x = lgρ, v represents the peak velocity of the particle; K represents the coefficient related to the site conditions and blasting method factors; α represents the vibration attenuation coefficient; Q represents the maximum single-shot charge; r represents the distance from the explosion center.

[0015] Furthermore, multiple groups of on-site blasting vibration monitoring data are obtained by setting vibration monitoring points on the inner side of the upper step walkway behind the blasting area, conducting multiple step blasting tests, and collecting multiple groups of on-site blasting vibration monitoring data at the vibration monitoring points.

[0016] Furthermore, the damage variable is calculated based on the longitudinal wave velocity test data of the rock mass at different damage depths before and after each blasting test; damage variable D = 1-(1-η) 2 ;in, V P2 represents the longitudinal wave velocity of the rock mass after the blasting test, V P1 It indicates the longitudinal wave velocity of the rock mass before the blasting test.

[0017] Furthermore, the method for obtaining the rock mass longitudinal wave velocity test data at different damage depths of the bench section is as follows:

[0018] The damage depth is recorded as x, and a long-term sonic hole is arranged in the step section where cumulative damage needs to be considered. An sonic test hole is arranged in the step section to be excavated by blasting. Before and after each blasting test, sonic tests are carried out at the hole depth x of the long-term sonic hole and the sonic test hole, respectively, to obtain the longitudinal wave velocity test data of the rock mass at the damage depth x; through multiple blasting tests, the longitudinal wave velocity test data of the rock mass corresponding to each blasting number at different damage depths are obtained.

[0019] Compared with the prior art, this application has the following advantages and beneficial effects:

[0020] This application is based on the cumulative damage effect of multiple blasting excavation of high slopes. Specifically, by analyzing the cumulative damage variables of the blasted excavation steps at the allowable damage depth of the retained rock mass on the rock high slope, the cumulative damage variables are considered to determine the peak vibration velocity threshold of the particle point during blasting, and the maximum single-shot charge is inferred based on the peak vibration velocity threshold of the particle point. The inferred maximum single-shot charge is used for blasting design. The blasting designed by the method of this application can ensure the stability and safety of the slope. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the process of the present application in a specific implementation manner;

[0022] Figure 2 It is a cross-sectional schematic diagram of the arrangement of vibration monitoring points and sonic holes in a specific implementation manner;

[0023] Figure 3 for Figure 2 A schematic plan view of the arrangement of the mesonic holes;

[0024] Figure 4 It is the fitting curve diagram of damage variable and damage depth under different blasting times;

[0025] Figure 5 It is the fitting curve diagram of the maximum damage depth and the peak velocity of the particle at different explosion center distances;

[0026] Figure numerals: blasting area 1, pre-cracking surface 2, vibration monitoring point 3, long observation sonic hole 4, sonic test hole 5. DETAILED DESCRIPTION

[0027] The following will be combined with specific implementations and drawings to clearly and completely describe the technical solution of this application. Obviously, the specific implementation described is only a part of the implementation of this application, not all of the implementations. Based on the specific implementation of this application, all other specific implementations obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0028] See also Figure 1 , which is a flowchart of a specific implementation method of the present application. The present application method includes three parts: on-site monitoring, data analysis and blasting design optimization. Figure 1 The specific implementation process of the blasting design method considering the cumulative damage effect in this application is described in detail, including:

[0029] (1) Using multiple sets of on-site blasting vibration monitoring data, regression fitting is performed on the blasting seismic wave attenuation law based on the Sadovsky formula;

[0030] Sadovsky formula is an empirical formula used to calculate the vibration velocity generated by blasting, and can also be used to reflect the attenuation law of blasting seismic waves. The specific implementation method of this step is as follows:

[0031] The Sadovsky formula is transformed into a linear formula y=αx+b. Based on multiple sets of on-site blasting vibration monitoring data, the coefficients α and b are solved using the least squares method, and the attenuation law of blasting seismic waves is obtained.

[0032] The Sadovsky formula is as follows:

[0033]

[0034] In formula (1), v represents the peak velocity of the particle, unit: cm / s; Q represents the maximum single-shot charge, unit: kg; r represents the distance from the blast center, unit: m; K represents the coefficient related to the site conditions and blasting method factors; α represents the vibration attenuation coefficient.

[0035] The process of transforming the nonlinear Sadovsky formula into a linear form is as follows:

[0036] make Taking the logarithm of both sides, we get:

[0037] lgv=lgK+αlgρ (2)

[0038] Let y = lgv, b = lgK, x = lgρ, we have:

[0039] y=αx+b (3)

[0040] The nonlinear relationship is converted into a linear relationship, and the least squares method is used to solve α and b, and a significance test is performed. Studies have shown that when the hole network parameters and topographic and geological conditions of each step are similar, the b and α obtained by fitting each step are similar. If the conditions are met, the vibration attenuation law obtained in a step can be applied to the blasting of other steps.

[0041] See also Figures 2-3 , which shows the positional relationship diagram of the blasting area 1, the pre-cracking surface 2, the vibration monitoring point 3, the long-view sonic hole 4, and the sonic test hole 5. Figure 2 Explain how to obtain multiple sets of on-site blasting vibration monitoring data:

[0042] In order to reduce the influence of the elevation amplification effect, the vibration monitoring point 3 is arranged on the inner side of the upper step road behind the blasting area 1, such as Figure 2 As shown; multiple step blasting tests were carried out, and multiple groups of on-site blasting vibration monitoring data were collected at 3 vibration monitoring points.

[0043] (2) Using multiple sets of rock mass longitudinal wave velocity test data before and after the blasting test, the damage of the retained rock mass of the blasted excavation section and the current blasting excavation section that need to consider the cumulative damage effect is determined, and the damage variables of each section at different damage depths are calculated respectively; the sections here include the blasted excavation section and the current blasting excavation section;

[0044] The damage variable D can be used to reflect the degree of damage to the rock mass caused by each blasting test, and is calculated based on the longitudinal wave velocity of the rock mass before and after the blasting test. The relationship between the damage variable D and the longitudinal wave velocity of the rock mass is established based on the elastic modulus, as follows:

[0045]

[0046] In formula (4), E0 represents the elastic modulus in the initial state; E represents the elastic modulus after blasting; V P2 Indicates the longitudinal wave velocity of the rock mass after blasting, unit: m / s; V P1 It represents the longitudinal wave velocity of the rock mass before blasting, unit: m / s; η represents the reduction rate of the longitudinal wave velocity of the rock mass after blasting, and the calculation formula of η is as follows:

[0047]

[0048] The damage variable threshold can be calculated according to the requirement of the rock mass longitudinal wave velocity reduction rate η. In this specific implementation, η>10% is required, so η=10% is used as the judgment standard into formula (4) to calculate the damage variable D=0.19, that is, the damage variable threshold.

[0049] In this specific implementation, multiple groups of rock mass longitudinal wave velocity test data before and after the blasting test are obtained as follows:

[0050] First, arrange the acoustic wave test holes in the rock mass of the terrace. The arrangement method is shown in Figures 2-3 , a Changguan sonic hole 4 is arranged in the step section where cumulative damage needs to be considered, and a sonic test hole 5 is arranged in the step section to be blasted and excavated. The Changguan sonic hole 4 is used to observe the sonic waves for a long time; 1 to 2 days before each blasting test, sonic tests are carried out in the Changguan sonic hole 4 and the sonic test hole 5 to obtain the longitudinal wave velocity test data of the step section rock mass; after the sonic test is completed, the Changguan sonic hole 4 and the sonic test hole 5 are filled with sand for protection; after the blasting test, the slag in the Changguan sonic hole 4 and the sonic test hole 5 is cleared out, and then the sonic test is carried out again.

[0051] Carry out 5 to 7 bench blasting tests, and collect multiple sets of rock longitudinal wave velocity test data before and after the blasting test.

[0052] It should be further explained that the damage variables of each step at different damage depths are calculated based on the rock mass longitudinal wave velocity test data at different damage depths, and the method for obtaining the rock mass longitudinal wave velocity test data at different damage depths is:

[0053] The damage depth is recorded as x. Sonic tests are carried out at the depth x of the Changguan sonic hole and the sonic test hole before and after each blasting test, respectively, to obtain the rock longitudinal wave velocity test data at the damage depth x; through multiple blasting tests, the rock longitudinal wave velocity test data corresponding to each blasting number at different damage depths are obtained.

[0054] (3) According to step (2), the cumulative damage variables of the blasted excavation steps at each damage depth after each blasting test are obtained, and the cumulative damage variables corresponding to each blasting number at different damage depths are further obtained. The data of the damage depth and the cumulative damage variables at each blasting number are respectively fitted to obtain a damage prediction model for the blasted excavation steps;

[0055] The cumulative damage variable is the accumulation of damage variables. Specifically, for the nth blasting test, the cumulative damage variable is the sum of the damage variables corresponding to the 1st to nth blasting tests. Figure 4 The damage prediction model can reflect the damage degree of the blasted excavation bench at different damage depths of the rock mass in each blasting.

[0056] (4) Multiple blasting tests were carried out at different blasting center distances. The peak vibration velocity of the particle point in each blasting test was calculated using the attenuation law of blasting seismic waves, and the damage depth of the step blasting slope was measured. The exponential function curve of the damage depth and the peak vibration velocity of the particle point at each blasting center distance was obtained through regression fitting.

[0057] The explosion center distance refers to the distance from the vibration monitoring point on the upper step road to the explosion center. In this specific implementation, different explosion center distances are obtained by adjusting the position of the vibration monitoring point, and multiple blasting tests are carried out at different explosion center distances. In this specific implementation, the exponential function curves of the damage depth and the peak vibration velocity of the particle point at explosion center distances of 20m and 30m are fitted, see Figure 5 shown.

[0058] (5) When designing blasting, obtain the exponential function curve of the damage depth and the peak vibration velocity of the particle at the distance from the blast center on site, take the peak vibration velocity of the particle corresponding to the maximum damage depth, and the peak vibration velocity of the particle is the threshold of the peak vibration velocity of the particle corresponding to the maximum damage depth of the retained rock mass of the high rock slope; substitute the threshold of the peak vibration velocity of the particle into the formula of the attenuation law of the blasting seismic wave, calculate the maximum single-shot charge, and optimize the blasting design based on the calculated maximum single-shot charge.

[0059] The maximum damage depth is determined by: determining the number of blasting and the damage variable threshold, and obtaining the damage depth corresponding to the determined number of blasting and the damage variable threshold from the damage prediction model, that is, the maximum damage depth. The damage variable threshold is required in advance, and in this specific implementation, the damage variable threshold is 0.19. The determined number of blasting is the actual number of blasting in the actual excavation of the step section at the engineering site.

[0060] Example

[0061] A dam shoulder slot right bank excavation project was selected. The dam shoulder slot is used as the foundation surface of the arch dam to ensure that the dam foundation retains the quality of rock excavation and minimizes the amount of over-excavation. The exposed rock mass on both sides of the dam site has a relatively smooth slope shape. The bedrock rock is mainly biotite quartz schist, which is hard and has strong resistance to weathering. The right bank dam foundation is all hard rock with good rock integrity. The excavation and support of the dam shoulder slot 800m~990m slope is divided into 13 layers for construction. The blasting height of each step is 15m, and the excavation volume of a single excavation area is controlled at 20,000m 3 The slope design contour surface is controlled by pre-splitting blasting to minimize the damage depth of blasting to the surface of the rock mass. The key point of the blasting design method is to reasonably control the maximum single-shot charge; link the blasting design method and the damage range through the particle peak velocity; consider the impact of the cumulative damage effect of multiple steps and multiple blasting, and finally control the rock mass damage depth within the design requirements.

[0062] Note that the above are only preferred embodiments of the present application and the technical principles used. Those skilled in the art will understand that the present application is not limited to the specific embodiments described herein, and that various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the protection scope of the present application. Therefore, although the present application is described in more detail through the above embodiments, the present application is not limited to the above embodiments, and may also include more other equivalent embodiments without departing from the concept of the present application, all of which belong to the protection scope of the present application.

Claims

1. A blasting design method considering cumulative damage effects, characterized in that: include: (1) Using multiple sets of on-site blasting vibration monitoring data, regression fitting is performed on the blasting seismic wave attenuation law based on the Sadovsky formula; (2) Using multiple sets of rock mass longitudinal wave velocity test data before and after the blasting test, the damage of the blasted excavation steps and the retained rock mass of the current blasting excavation steps that need to consider the cumulative damage effect is determined, and the damage variables of each step at different damage depths are calculated respectively; (3) According to step (2), the cumulative damage variables of the blasted excavation steps at each damage depth after each blasting test are obtained, and the cumulative damage variables corresponding to each blasting number at different damage depths are further obtained. The data of the damage depth and the cumulative damage variables at each blasting number are respectively fitted to obtain a damage prediction model for the blasted excavation steps; (4) Multiple blasting tests were carried out at different blasting center distances. The peak vibration velocity of the particle point in each blasting test was calculated using the attenuation law of blasting seismic waves, and the damage depth of the step blasting slope was measured. The exponential function curve of the damage depth and the peak vibration velocity of the particle point at each blasting center distance was obtained through regression fitting. (5) When designing blasting, obtain the exponential function curve of the damage depth and the peak vibration velocity of the particle corresponding to the distance from the explosion center on site, take the peak vibration velocity of the particle corresponding to the maximum damage depth, bring the peak vibration velocity of the particle into the attenuation law of the blasting seismic wave, calculate the maximum single-shot charge, and optimize the blasting design based on the maximum single-shot charge; The maximum damage depth is determined by determining the number of blasting times and the damage variable threshold, and obtaining the damage depth corresponding to the determined number of blasting times and the damage variable threshold from the damage prediction model, that is, the maximum damage depth.

2. The blasting design method considering cumulative damage effect as claimed in claim 1 is characterized by: Step (1) specifically comprises: transforming the Sadovsky formula into a linear formula y=αx+b, performing regression fitting on the linear formula using multiple sets of on-site blasting vibration monitoring data, solving coefficients α and b, and obtaining the attenuation law of blasting seismic waves; Among them, y = lgv, b = lgK, x = lgρ, v represents the peak velocity of the particle; K represents the coefficient related to the site conditions and blasting method factors; α represents the vibration attenuation coefficient; Q represents the maximum single-shot charge; r represents the distance from the explosion center.

3. The blasting design method considering cumulative damage effect as claimed in claim 1 or 2, characterized in that: The multiple groups of on-site blasting vibration monitoring data are obtained by setting vibration monitoring points on the inner side of the upper step road behind the blasting area, carrying out multiple step blasting tests, and collecting multiple groups of on-site blasting vibration monitoring data at the vibration monitoring points.

4. The blasting design method considering cumulative damage effect as claimed in claim 1 is characterized by: The damage variables are calculated based on the rock mass longitudinal wave velocity test data at different damage depths of the bench before and after each blasting test; Damage variable D = 1-(1-η) 2 ;in, V P2 represents the longitudinal wave velocity of the rock mass after the blasting test, V P1 It indicates the longitudinal wave velocity of the rock mass before the blasting test.

5. The blasting design method considering cumulative damage effect as claimed in claim 4 is characterized by: The method for obtaining the rock mass longitudinal wave velocity test data at different damage depths of the step section is as follows: The damage depth is recorded as x, and a long-view sonic hole is arranged in the step section where cumulative damage needs to be considered. An sonic test hole is arranged in the step section to be excavated by blasting. Before and after each blasting test, sonic tests are carried out at the depth x of the long-view sonic hole and the sonic test hole, respectively, to obtain the longitudinal wave velocity test data of the rock mass at the damage depth x; through multiple blasting tests, the longitudinal wave velocity test data of the rock mass corresponding to each blasting number at different damage depths are obtained.

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