Step blasting delay parameter determination method based on new free surface evolution

Abstract

The invention discloses a bench blasting delay parameter determination method based on new free surface evolution, which comprises the following steps: S1, establishing a 3D-DIC in-situ experiment system, and collecting three-dimensional displacement field dynamic data of an ore rock mass in single-hole bench blasting and double-hole bench blasting processes; and S2, identifying an initial forming moment, a spatial position and a full-period evolution process of a new free surface by taking the ore rock mass out-of-plane displacement not less than 10cm as a new free surface forming criterion. According to the method, delay parameters are determined on the basis of new free surface evolution data actually measured on site, subjectivity of empirical design is avoided, and inter-hole and inter-row delay is accurately matched with a new free surface expansion rule; the method realizes collaborative optimization of vibration control and crushing effect, is suitable for large-scale bench blasting of large surface mines, can be directly applied to an electronic detonator hole-by-hole detonating system, and improves the safety and economy of blasting engineering.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of bench blasting, and particularly relates to a bench blasting delay parameter determination method based on new free surface evolution. BACKGROUND

[0002] Bench blasting is the core process of large open-pit mine exploitation, and the rationality of delay parameters directly affects the blasting vibration control and the rock breaking effect. In the prior art, the delay parameter design mainly depends on empirical formula or small-scale laboratory experiment, and the dynamic evolution characteristics of the new free surface in the field blasting are not fully considered, resulting in the contradiction between vibration control and breaking effect: long delay time can reduce vibration but weaken the inter-hole rock breaking effect, and short delay time can improve the breaking effect but easily cause vibration superposition exceeding the standard.

[0003] The prior art has the following disadvantages: 1. The quantitative correlation between the new free surface evolution and the delay parameter is not established, and the formation time and expansion law of the new free surface lack field measurement data support; 2. The vibration synthesis method does not consider the influence of the free surface change on the rear row of blast holes, and the prediction error is large; 3. It is difficult to realize the collaborative optimization of vibration control and breaking effect, which restricts the safety and efficiency of bench blasting. Therefore, there is an urgent need for a delay parameter determination method based on the field measurement of the evolution characteristics of the new free surface. SUMMARY

[0004] The present application relates to the technical field of bench blasting, and particularly relates to a bench blasting delay parameter determination method based on new free surface evolution.

[0005] In order to achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows: A bench blasting delay parameter determination method based on new free surface evolution, comprising the following steps: S1, a 3D-DIC in-situ experiment system is established to collect three-dimensional displacement field dynamic data of the rock mass in the process of single-hole bench blasting and double-hole bench blasting; S2, taking the displacement of the rock mass from the surface not less than 10cm as the new free surface formation criterion, identifying the initial formation time, spatial position and full-cycle evolution process of the new free surface; S3, based on the change of the new free surface expansion speed, dividing the slow expansion stage, high-speed expansion stage and expansion convergence stage, determining the single-hole blasting new free surface high-speed expansion end time and the double-hole blasting new free surface high-speed expansion end time; S4, determining the inter-hole delay time according to the single-hole blasting new free surface high-speed expansion end time, determining the inter-row delay time according to the difference between the double-hole blasting new free surface high-speed expansion end time and the inter-hole delay time, and obtaining the bench blasting delay parameter combination.

[0006] Preferably, in the step S1, the 3D-DIC in-situ experiment system comprises an ultra-high-speed camera, a synchronous control instrument and a data processing module, the shooting frame rate of the ultra-high-speed camera is not less than 5000 frames / s, the image resolution is not less than 1280*800 pixels, and the three-dimensional displacement calculation accuracy is not more than 0.3 mm.

[0007] Preferably, in the step S2, the three-dimensional displacement field data comprises a horizontal displacement, a vertical displacement and an out-of-plane displacement, wherein the out-of-plane displacement is a displacement component perpendicular to the step slope surface, and is used to represent the formation and expansion degree of the new free surface.

[0008] Preferably, in the step S3, the new free surface expansion speed is calculated by the ratio of the area difference of the new free surface at adjacent time points and the time interval, wherein the expansion speed in the slow expansion stage is not more than 0.8 m² / ms, the expansion speed in the high-speed expansion stage is greater than 0.8 m² / ms, and the expansion speed in the expansion convergence stage falls back to not more than 0.8 m² / ms.

[0009] Preferably, in the step S3, the end time of the high-speed expansion of the single-hole blasting new free surface is identified by the inflection point of the area-time evolution curve of the single-hole blasting new free surface, and the inflection point corresponds to the time when the expansion speed falls back from the peak value to 0.8 m² / ms; the end time of the high-speed expansion of the double-hole blasting new free surface is identified by the inflection point of the area-time evolution curve of the double-hole blasting new free surface, and the identification standard is consistent with that of the single-hole blasting.

[0010] Preferably, in the step S4, the hole interval delay is the difference between the end time of the high-speed expansion of the single-hole blasting new free surface and the zero time of the single-hole initiation, the row interval delay is the difference between the end time of the high-speed expansion of the double-hole blasting new free surface and the hole interval delay, and the hole interval delay ranges from 20 ms to 25 ms, and the row interval delay ranges from 55 ms to 65 ms.

[0011] Preferably, in the step S2, the evolution process of the double-hole blasting new free surface is quantitatively characterized by a fourth-order polynomial model, the determination coefficient of the model is not less than 0.99, the model takes the new free surface area as the dependent variable and the time after initiation as the independent variable, and the evolution law is accurately described by the fitting coefficient.

[0012] Preferably, in the step S4, the obtained delay parameters need to be verified by field blasting experiments, and the verification indexes include that the proportion of the broken rock block with a size not greater than 0.38 m is not less than 70%, the peak value of blasting vibration is not more than 3.0 cm / s, and the blast pile shape is uniform without obvious large block accumulation.

[0013] Compared with the prior art, the present application has the following beneficial effects: 1. In the present application, the delay parameters are determined based on the in-situ measured new free surface evolution data, thereby avoiding the subjectivity of experience design, and the hole interval delay and the row interval delay are accurately matched with the new free surface expansion law.

[0014] 2、The vibration control and the breaking effect are cooperatively optimized in the application, the vibration speed peak value can be controlled below 3.0 cm / s, the breaking block size is not more than 0.38 m, and the proportion is not less than 70%, and the low-frequency vibration energy proportion is not more than 16%.

[0015] 3、The application is suitable for large-scale bench blasting in large open-pit mines, can be directly applied to the electronic detonator hole-by-hole initiation system, and improves the safety and economy of the blasting engineering. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 A flow chart of a bench blasting delay parameter determination method based on new free surface evolution is provided in the application. DETAILED DESCRIPTION

[0017] The technical solutions in the embodiments of the application will be clearly and completely described below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments of the application.

[0018] REFERENCE Figure 1 A bench blasting delay parameter determination method based on new free surface evolution comprises the following steps: S1, a 3D-DIC in-situ experiment system is established to collect three-dimensional displacement field dynamic data of a mine rock mass in a single-hole bench blasting and double-hole bench blasting process; S2, taking that the displacement of the mine rock mass away from the surface is not less than 10 cm as a new free surface formation criterion, identifying the initial formation time, spatial position and full-cycle evolution process of the new free surface; S3, based on the change of the new free surface expansion speed, dividing a slow expansion stage, a high-speed expansion stage and an expansion convergence stage, and determining the single-hole blasting new free surface high-speed expansion end time and the double-hole blasting new free surface high-speed expansion end time; S4, taking the single-hole blasting new free surface high-speed expansion end time to determine the hole-to-hole delay, taking the difference between the double-hole blasting new free surface high-speed expansion end time and the hole-to-hole delay to determine the row-to-row delay, and obtaining a bench blasting delay parameter combination.

[0019] In step S1, the 3D-DIC in-situ experiment system comprises an ultra-high-speed camera, a synchronous control instrument and a data processing module, the shooting frame rate of the ultra-high-speed camera is not less than 5000 frames / s, the image resolution is not less than 1280*800 pixels, and the three-dimensional displacement calculation accuracy is not more than 0.3 mm.

[0020] In step S2, the three-dimensional displacement field data comprises horizontal displacement, vertical displacement and displacement away from the surface, wherein the displacement away from the surface is a displacement component perpendicular to the bench slope surface, and is used to represent the formation and expansion degree of the new free surface.

[0021] In step S3, the new free surface expansion speed is calculated by the ratio of the difference in the area of the new free surface at adjacent time points and the time interval, wherein the expansion speed in the slow expansion stage is not more than 0.8 m² / ms, the expansion speed in the high-speed expansion stage is greater than 0.8 m² / ms, and the expansion speed in the expansion convergence stage falls to not more than 0.8 m² / ms.

[0022] In step S3, the end time of the high-speed expansion of the new free surface in single-hole blasting is identified by the inflection point of the area-time evolution curve of the new free surface, which corresponds to the time when the expansion speed falls from the peak value to 0.8 m² / ms; the end time of the high-speed expansion of the new free surface in double-hole blasting is identified by the inflection point of the area-time evolution curve of the new free surface, which has the same identification standard as single-hole blasting.

[0023] In step S4, the inter-hole delay is the difference between the end time of the high-speed expansion of the new free surface in single-hole blasting and the zero time of single-hole initiation, the inter-row delay is the difference between the end time of the high-speed expansion of the new free surface in double-hole blasting and the inter-hole delay, and the inter-hole delay ranges from 20 ms to 25 ms and the inter-row delay ranges from 55 ms to 65 ms.

[0024] In step S2, the evolution process of the new free surface in double-hole blasting is quantitatively characterized by a fourth-order polynomial model, the determination coefficient of which is not less than 0.99, the model takes the area of the new free surface as the dependent variable and the time after initiation as the independent variable, and accurately describes the evolution law through the fitting coefficients.

[0025] In step S4, the obtained delay parameters need to be verified by field blasting experiments, and the verification indicators include: the proportion of broken rock fragments not greater than 0.38 m is not less than 70%, the peak value of blasting vibration is not more than 3.0 cm / s, and the blast pile shape is uniform without obvious large block accumulation.

[0026] The key of the present application is to realize the quantitative characterization of the evolution of the new free surface in field blasting by 3D-DIC technology, and the core innovation point is to take the end time of the high-speed expansion of the new free surface as the core basis for the design of the delay parameter, so that the post-blast hole can fully utilize the new free surface formed by the pre-blast hole, while avoiding vibration superposition. In practical application, the off-surface displacement threshold and expansion speed division standard of the new free surface formation criterion can be adjusted according to the mine lithology and step parameters to ensure the adaptability of the method.

[0027] The above is only the preferred specific implementation mode of the present application, but the protection scope of the present application is not limited thereto, any skilled person in the art can make equivalent replacement or change within the technical range disclosed by the present application according to the technical solution and inventive concept of the present application, which should be covered within the protection scope of the present application.

Claims

1. A method for determining the delay parameters of step blasting based on the evolution of a new free surface, characterized in that, Includes the following steps: S1. Establish a 3D-DIC in-situ experimental system to collect dynamic data of the three-dimensional displacement field of the ore and rock mass during single-hole bench blasting and double-hole bench blasting. S2. Using a displacement of not less than 10cm from the surface of the ore body as the criterion for the formation of a new free surface, identify the initial formation time, spatial location and full-cycle evolution process of the new free surface; S3. Based on the change in the expansion rate of the new free surface, the slow expansion stage, the high-speed expansion stage and the expansion convergence stage are divided to determine the end time of high-speed expansion of the new free surface in single-hole blasting and the end time of high-speed expansion of the new free surface in double-hole blasting. S4. Determine the inter-hole delay based on the end time of high-speed expansion of the new free surface in single-hole blasting, and determine the inter-row delay based on the difference between the end time of high-speed expansion of the new free surface in double-hole blasting and the inter-hole delay, thus obtaining the combination of step blasting delay parameters.

2. The method for determining the step blasting delay parameter based on the evolution of a new free surface according to claim 1, characterized in that, In step S1, the 3D-DIC in-situ experimental system includes an ultra-high-speed camera, a synchronous controller, and a data processing module. The ultra-high-speed camera has a shooting frame rate of no less than 5000 frames / second, an image resolution of no less than 1280×800 pixels, and a three-dimensional displacement calculation accuracy of no more than 0.3mm.

3. The method for determining the step blasting delay parameter based on the evolution of a new free surface according to claim 1, characterized in that, In step S2, the three-dimensional displacement field data includes horizontal displacement, vertical displacement, and out-of-plane displacement, where the out-of-plane displacement is the displacement component perpendicular to the slope of the step, used to characterize the degree of formation and expansion of the new free surface.

4. The method for determining the step blasting delay parameter based on the evolution of a new free surface according to claim 1, characterized in that, In step S3, the expansion rate of the new free surface is calculated by the ratio of the difference in the area of ​​the new free surface at adjacent times to the time interval. The expansion rate during the slow expansion phase does not exceed 0.8 m² / ms, the expansion rate during the high-speed expansion phase is greater than 0.8 m² / ms, and the expansion rate during the expansion convergence phase drops back to no more than 0.8 m² / ms.

5. The method for determining the step blasting delay parameter based on the evolution of a new free surface according to claim 1, characterized in that, In step S3, the end time of high-speed expansion of the new free surface in single-hole blasting is identified by the inflection point of the area-time evolution curve of the new free surface in single-hole blasting. This inflection point corresponds to the moment when the expansion velocity drops from the peak to 0.8 m² / ms. The end time of high-speed expansion of the new free surface in double-hole blasting is identified by the inflection point of the area-time evolution curve of the new free surface in double-hole blasting. The identification criteria are the same as those for single-hole blasting.

6. The method for determining the step blasting delay parameter based on the evolution of a new free surface according to claim 1, characterized in that, In step S4, the inter-hole delay is the difference between the end time of the high-speed expansion of the new free surface after single-hole blasting and the zero time of single-hole initiation, and the inter-row delay is the difference between the end time of the high-speed expansion of the new free surface after double-hole blasting and the inter-hole delay. The inter-hole delay ranges from 20ms to 25ms, and the inter-row delay ranges from 55ms to 65ms.

7. The method for determining the step blasting delay parameter based on the evolution of a new free surface according to claim 1, characterized in that, In step S2, the evolution process of the new free surface after dual-hole blasting is quantitatively characterized by a fourth-order polynomial model with a determination coefficient of not less than 0.

99. The model uses the area of ​​the new free surface as the dependent variable and the time after detonation as the independent variable, and accurately describes the evolution law through the fitting coefficient.

8. The method for determining the step blasting delay parameter based on the evolution of a new free surface according to claim 1, characterized in that, In step S4, the obtained delay parameters need to be verified by on-site blasting experiments. The verification indicators include: the proportion of broken rock blocks with a size not greater than 0.38m is not less than 70%, the peak velocity of blasting vibration does not exceed 3.0cm / s, and the blast pile shape is uniform without obvious large block accumulation.

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