Blasting vibration prediction method considering influence of dip angle of fault zone

Abstract

The invention discloses a blasting vibration prediction method considering the influence of the dip angle of a fault zone, and relates to the field of blasting engineering and blasting vibration prediction.The blasting vibration prediction method comprises the following steps that physical and mechanical parameters of a rock mass and the fault zone on a blasting vibration propagation path are collected, and a rock mass blasting numerical model containing the fault zone is established through dynamic finite element software LS-DYNA; the blasting load peak intensity acting on the blast hole wall is obtained through calculation based on the detonation wave theory, and the attenuation process of the blasting load on the blast hole wall is simulated through a double-exponential curve; and calculating blasting numerical models of different fault zone inclination angles, determining the range of a blasting vibration amplification area in front of the fault zone, and proposing a prediction formula of the blasting vibration amplification area considering the fault zone inclination angles. According to the method, the emission superposition amplification effect of the fault zone on blasting vibration is considered, the peak vibration speed of the blasting vibration amplification area in front of the fault zone can be effectively predicted, the accuracy of blasting vibration full-path prediction is improved, and reference can be provided for blasting vibration safety control.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of blasting engineering and blasting vibration prediction, and particularly relates to a blasting vibration prediction method considering the influence of fault zone dip angle. BACKGROUND

[0002] The site condition and medium characteristics of the blasting site directly affect the propagation law of the blasting vibration wave. In the current engineering practice, the Sadovnikov formula is the most widely used blasting vibration prediction model, and the core parameters K (coefficient) and a (blasting vibration attenuation coefficient) are respectively related to the propagation medium properties and the blasting working condition. Under normal circumstances, when the single initiation explosive quantity is fixed, the blasting peak vibration velocity is negatively correlated with the blast distance, and at this time the Sadovnikov formula can achieve good prediction effect.

[0003] However, if there is a fault zone in the blasting vibration propagation path, the vibration wave will be transmitted and reflected at the fault interface, resulting in significant amplification of the vibration velocity within a certain range in front of the fault zone; and the strength of the amplification effect is also regulated by the dip angle of the fault zone. Since the Sadovnikov formula does not take into account the key influencing factor of the fault zone, its applicability is limited in blasting engineering with fault zones in the propagation path, and it is difficult to meet the precise prediction requirements.

[0004] Therefore, a blasting vibration prediction method considering the influence of fault zone dip angle is proposed, which can accurately predict the peak vibration velocity in the vibration amplification area in front of the fault zone, thereby improving the prediction accuracy of the whole propagation path of the blasting vibration, and providing reliable technical support for the safety control of rock mass blasting construction. SUMMARY

[0005] (I) Invention purpose To solve the technical problems in the background art, the present application provides a blasting vibration prediction method considering the influence of fault zone dip angle, which effectively predicts the peak vibration velocity in the blasting vibration amplification area in front of the fault zone, improves the accuracy of the whole path prediction of the blasting vibration, and provides a reference for the safety control of blasting vibration.

[0006] (II) Technical scheme The present application provides a blasting vibration prediction method considering the influence of fault zone dip angle, comprising the following steps: Step 1: Collect the physical and mechanical parameters of the rock blasting engineering site topography condition, rock mass and fault zone, use CAD and MechanicalAPDL to establish a three-dimensional numerical model of rock mass blasting containing fault zones with different dip angles, and output the model as a k file format, use LS-PrePost post-processing software to assign the physical and mechanical parameters of the rock mass and fault zone, and set the boundary conditions of the model; Step two: Based on the theory of detonation wave, the blasting load of the explosive acting on the blast hole wall was calculated, the LS-PrePost post-processing software was used to apply the blasting load time curve on the blast hole wall, and finally the LS-DYNA Program Manager software was used for numerical calculation; Step three: The LS-PrePost post-processing software was used to extract the blasting vibration time curve of the particles from the blast source to the front of the fault zone in the calculation results, the peak vibration velocity of each particle was counted, and the blasting vibration amplification area range under the influence of different dip angle fault zones was obtained; Step four: Based on the peak vibration velocity variation law of the particles in the blasting amplification area in the numerical model of the fault zone with different dip angles, a prediction formula of the blasting vibration amplification area considering the dip angle of the fault zone was proposed, the independent variables were substituted into the formula fitting, and the correlation coefficient R 2 was used to judge the rationality of the prediction formula, and finally the parameters of the prediction formula were obtained.

[0007] Further, the rock mass and fault zone in the numerical model use the PLASTIC_KINEMATIC model, and the physical and mechanical parameters include material density, Young's modulus, Poisson's ratio, yield strength, tangent modulus and hardening coefficient.

[0008] Further, the establishment process of the numerical model includes the following steps: S1, a two-dimensional contour graph of a three-dimensional rock mass blasting numerical model containing fault zones with different dip angles is established by CAD, the blast hole position is reserved, then the CAD graph is imported into Mechanical APDL, and is expanded into a three-dimensional model, and part and mesh division are carried out, wherein the mesh size is 20 cm, the minimum mesh size near the blast hole is 2.45 cm, and it is output as a k file format.

[0009] S2, the material parameters and boundary conditions of the numerical model are given by using the LS-PrePost post-processing software, the boundary conditions include non-reflecting boundary and free boundary, and the non-reflecting boundary is set by using the keyword BOUNDARY_NON_REFLECTING, wherein, in addition to the free boundary, the rest of the surface is set as non-reflecting boundary.

[0010] S3, when coupling the charge based on the theory of detonation wave, the peak pressure of the blasting load on the blast hole wall P 0 can be calculated by the following formula:

[0011] wherein, p 0 is the density of the explosive, (unit: kg / m 3 ); V D is the detonation velocity of the explosive, (unit m / s); g is the expansion adiabatic index of the detonation product.

[0012] The blasting load time-history curve on the borehole wall is a double exponential decay type, which can be expressed by the following formula:

[0013] wherein, P 0 is the peak pressure of the blasting load; t is the blasting load action time (unit: s); t0 is the blasting load rising time (unit: s); The blasting load time-history curve is defined by the keyword DEFINE_CURVE and applied by the keyword LOAD_SEGMENT_SET.

[0014] Further, based on the numerical calculation results, the prediction formula of the blasting vibration amplification area considering the fault zone dip angle is expressed as:

[0015] wherein, PPV is the peak particle velocity (unit: cm / s); k is a coefficient related to the blasting site conditions; Q is the single explosive charge (unit: kg); R is the blast center distance (unit: m); θ is the fault zone dip angle (unit: °); and α and β are the attenuation coefficients corresponding to the fault zone dip angle and the explosive charge, respectively.

[0016] Further, the Origin software is used for fitting analysis of the prediction formula, and the correlation coefficient R 2 judges the rationality of the prediction formula, and finally obtains the parameters of the prediction formula.

[0017] Compared with the prior art, the above technical scheme of the present application has the following beneficial technical effects: 1. The blasting vibration prediction method considering the influence of the fault zone dip angle, by accurately quantifying the reflection amplification effect of the fault zone, effectively makes up for the large prediction deviation under complex geological conditions, improves the accuracy and reliability of the blasting peak vibration prediction, and provides more accurate technical support for the safety control of blasting construction in complex fault-containing geological areas.

[0018] 2. The blasting vibration prediction method considering the influence of the fault zone dip angle can define the range boundary of the vibration amplification area in front of the fault zone and predict the peak blasting vibration intensity in the area, which provides direct reference for blasting construction hazard area division and protection measure arrangement, and relying on the prediction method can greatly reduce the workload and cost input of the field vibration monitoring test, avoid the resource waste caused by a large number of repeated tests, improve the construction efficiency and reduce the total engineering cost under the premise of ensuring construction safety. DETAILED DESCRIPTION

[0019] Figure 1 is a flowchart of the blasting vibration prediction method considering the influence of the fault zone dip angle.

[0020] Figure 2 A three-dimensional numerical model of rock mass blasting with a 75°-inclined fault zone and monitoring point selection established in the embodiment of the present application.

[0021] Figure 3 A blasting load time history curve on the borehole wall used in the embodiment of the present application.

[0022] Figure 4 A blasting vibration cloud chart of the 75°-inclined fault zone model at 0.0085 s in the embodiment of the present application.

[0023] Figure 5 A fitting image of the prediction formula of the blasting vibration amplification area considering the fault zone inclination in the present application. DETAILED DESCRIPTION

[0024] To make the objectives, technical solutions and advantages of the present application clearer and more comprehensible, the present application is further described in detail below with reference to the specific embodiments and the accompanying drawings. It should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present application. In addition, in the following description, the description of the known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present application.

[0025] Embodiment One As shown in Figures 1-5 The present application provides a blasting vibration prediction method considering the influence of fault zone inclination, comprising the following steps: Step One: Collect the physical and mechanical parameters of the rock blasting engineering site terrain conditions, rock mass and fault zone, use CAD and Mechanical APDL to establish a three-dimensional numerical model of rock mass blasting with different inclination fault zones, and output the model as a k file format, use LS-PrePost post-processing software to assign the physical and mechanical parameters of the rock mass and fault zone, and set the boundary conditions of the model; Specifically, according to the collected terrain condition data of the rock blasting engineering site, on this basis, first build a two-dimensional geometric model of rock mass with different inclination fault zones in CAD software, clearly define the key profile, fault distribution and relative position relationship of the model, complete the size calibration and topology optimization of the two-dimensional model, and then export it as a compatible format; then import the two-dimensional model into Mechanical APDL software to further build a three-dimensional numerical model of rock mass blasting with different inclination fault zones, complete the meshing and quality checking of the three-dimensional model, and then output the model as a k file format; finally, use LS-PrePost post-processing software to assign corresponding physical and mechanical parameters to the rock mass and different inclination fault zones in the model.

[0026] In the numerical model, the rock mass and fault zone are modeled by PLASTIC KINEMATIC model, and the physical and mechanical parameters include material density, Young's modulus, Poisson's ratio, yield strength, tangent modulus and hardening coefficient.

[0027] Step two: based on the theory of detonation wave, the blasting load of the explosive acting on the blast hole wall is calculated, the LS-PrePost post-processing software is used to apply the blasting load time curve on the blast hole wall, and finally the LS-DYNA Program Manager software is used for numerical calculation; Step three: the LS-PrePost post-processing software is used to extract the blasting vibration time curve of the particles from the blast source to the front of the fault zone in the calculation results, the peak vibration velocity of each particle is counted, and the blasting vibration amplification area range under the influence of different dip angle fault zones is obtained; Step four: based on the peak vibration velocity variation of the particles in the blasting amplification area in the numerical model of the fault zone with different dip angles, a prediction formula of the blasting vibration amplification area considering the dip angle of the fault zone is proposed, the independent variables are substituted into the formula fitting, and the correlation coefficient R 2 The rationality of the prediction formula is judged, and finally the parameters of the prediction formula are obtained.

[0028] Specifically, based on the numerical calculation results, the prediction formula of the blasting vibration amplification area considering the dip angle of the fault zone is represented as:

[0029] Wherein, PPV is the peak particle vibration velocity (unit: cm / s); k is a coefficient related to the blasting site conditions; Q is the single initiation explosive charge (unit: kg); R is the distance from the blast center (unit: m); θ is the dip angle of the fault zone (unit: °); α and β are the attenuation coefficients corresponding to the dip angle of the fault zone and the initiation explosive charge, respectively.

[0030] The Origin software is used for fitting analysis of the prediction formula, and the correlation coefficient R 2 The rationality of the prediction formula is judged, and finally the parameters of the prediction formula are obtained.

[0031] Further, the establishment process of the numerical model includes the following steps: S1, a two-dimensional contour graph of a three-dimensional rock mass blasting numerical model containing fault zones with different dip angles is established by CAD, the blast hole position is reserved, then the CAD graph is imported into Mechanical APDL, and is expanded into a three-dimensional model, and part and mesh division are carried out, wherein the mesh size is 20 cm, the minimum mesh size near the blast hole is 2.45 cm, and it is output as a k file format.

[0032] S2, the LS-PrePost post-processing software is used to give the material parameters and boundary conditions of the numerical model, the boundary conditions include non-reflecting boundary and free boundary, and the non-reflecting boundary is set by the keyword BOUNDARY_NON_REFLECTING, wherein, in addition to the free boundary, the rest of the surface is set as the non-reflecting boundary.

[0033] S3, when coupling the charge based on the detonation wave theory, the peak pressure of the blasting load on the blast hole wall P 0 can be calculated by the following formula:

[0034] wherein, p 0 is the density of the explosive, (unit: kg / m 3 ); V D is the detonation velocity of the explosive, (unit m / s); g is the expansion adiabatic index of the detonation product, preferably g = 3.

[0035] The blasting load time history curve on the blast hole wall is of a double exponential decay type, which can be expressed by the following formula:

[0036] wherein, P 0 is the peak pressure of the blasting load; t is the blasting load action time (unit: s); t0 is the blasting load rising time (unit: s); The blasting load time history curve is defined by the keyword DEFINE_CURVE and applied by the keyword LOAD_SEGMENT_SET.

[0037] Example two Example one has illustrated the core process of the present application, in order to further verify the implementability of the present application and clarify its adaptation ability in complex scenarios, the following will be described in detail by example two: The present embodiment adopts the steps completely consistent with example one, but according to its specific conditions, according to the collected physical and mechanical parameters of the rock blasting engineering site terrain conditions, rock mass and fault zone, the specific parameters are as follows: The rock mass and fault zone in the numerical model adopt the PLASTIC_KINEMATIC model, the density of the rock mass is 2.6 g / cm 3 , the Young's modulus is 31.3 GPa, the Poisson's ratio is 0.27, the yield strength is 67.2 MPa, the tangent modulus is 11.3 GPa, and the hardening coefficient is 0.5; the density of the fault zone is 2.06 g / cm 3 , the Young's modulus is 1 GPa, the Poisson's ratio is 0.3, the yield strength is 1.6 MPa, the tangent modulus is 0.05 GPa, and the hardening coefficient is 0.5.

[0038] The specific numerical model establishment process includes the following steps: S1, using CAD to establish a two-dimensional contour line diagram of a three-dimensional rock mass blasting numerical model containing fault zones with different dip angles, and reserving blast hole positions, wherein the width of the fault zone is 2 m, the dip angles are 60°, 75°, 90°, 105° and 120°, the distance from the blast hole center to the fault zone is 30.2 m, and the rock thickness is 10 m; the CAD diagram is imported into Mechanical APDL and expanded into a three-dimensional model with an expansion width of 10 m; part and mesh division are performed, wherein the mesh size is 20 cm, the minimum mesh size near the blast hole is 2.45 cm, and it is output in k file format.

[0039] S2, using LS-PrePost post-processing software to assign material parameters and boundary conditions to the numerical model, wherein the non-reflecting boundary is set by the keyword BOUNDARY_NON_REFLECTING.

[0040] S3, when coupling the charge based on the detonation wave theory, the peak pressure of the blasting load on the blast hole wall P 0 can be calculated by the following formula:

[0041] Wherein, the type of explosive is selected according to the site conditions, and the parameter values are as follows: the density of the explosive =920 kg / m3, the detonation velocity of the explosive V D =3000 m / s, and the expansion adiabatic index of the detonation product γ=3. After calculation, the peak pressure of the blasting load on the blast hole wall =1035 MPa.

[0042] The blasting load time history curve on the blast hole wall is of a double exponential decay type, which can be expressed by the following formula:

[0043] Wherein, P 0 is the peak pressure of the blasting load; t is the blasting load action time (unit: s); t 0 is the blasting load rise time, which is 1 ms.

[0044] Save the blasting load time history curve in Excel format and define it by the keyword DEFINE_CURVE and apply it by the keyword LOAD_SEGMENT_SET.

[0045] S4, using LS-DYNA Program Manager software for numerical calculation.

[0046] ​According to the actual engineering working conditions, the peak vibration velocity of the particle along the connecting line from the blast hole center to the fault zone in the numerical model of the fault zone with different dip angles is extracted, and the boundary range of the blasting vibration amplification area is determined accordingly. The vibration amplification area range corresponding to the blasting numerical model of the fault zone with different dip angles is shown in the following table:

[0047] In the table, the amplification area range refers to the distance of the particle at the farthest place in the amplification area from the fault zone.

[0048] Based on the variation law of the peak vibration velocity of the particle in the amplification area, the prediction formula of the blasting vibration amplification area considering the dip angle of the fault zone is proposed as follows:

[0049] Wherein, PPV is the peak particle velocity (unit: cm / s); k is a coefficient related to the blasting site conditions; Q is the single initiation explosive quantity (unit: kg); R is the blast distance (unit: m); is the dip angle of the fault zone (unit: °); α , β are the attenuation coefficients corresponding to the dip angle of the fault zone and the initiation explosive quantity, respectively.

[0050] The peak vibration velocity of the particle in the blasting vibration amplification area and the corresponding independent variable are substituted into the prediction formula proposed above, and the fitting analysis of the prediction formula is carried out by using Origin software. The fitting result shows that the parameter value is k =4.164e -28 , α =-0.482, β =-25.064, and the correlation coefficient R 2 is 0.912. The R 2 value indicates that the fitting accuracy of the prediction formula is high and has good reliability.

[0051] It should be noted that in the engineering and scientific research fields, it is generally considered that when R 2 > 0.8, the fitting model has strong explanatory ability; and when R 2 > 0.9, it belongs to the high fitting level. In this embodiment, R 2 = 0.912, which has exceeded the threshold value of 0.9, which is sufficient to reflect the high fitting accuracy of the formula.

[0052] Although the embodiments of the present application have been shown and described, it can be understood by those skilled in the art that various changes, modifications, replacements and variations can be made to these embodiments without departing from the principles and spirits of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A method for predicting blasting vibration considering the influence of fault dip angle, characterized in that, Includes the following steps: Step 1: Collect the topographic conditions, physical and mechanical parameters of the rock mass and fault zones at the rock blasting site. Use CAD and MechanicalAPDL to establish a three-dimensional numerical model of the rock mass blasting with fault zones of different dip angles. Output the model as a k file. Use LS-PrePost post-processing software to assign physical and mechanical parameters to the rock mass and fault zones, and set the boundary conditions of the model. Step 2: Calculate the blast load on the borehole wall based on the detonation wave theory. Apply the blast load time history curve to the borehole wall using LS-PrePost post-processing software. Finally, perform numerical calculations using LS-DYNAProgramManager software. Step 3: Use LS-PrePost post-processing software to extract the blasting vibration time history curves of the particles from the blast source to the front of the fault zone in the calculation results, count the peak vibration velocity of each particle, and obtain the range of blasting vibration amplification area under the influence of fault zones with different dip angles; Step 4: Based on the variation law of peak vibration velocity of particles in the blasting amplification region in the numerical model of fault zones with different dip angles, a prediction formula for the blasting vibration amplification region considering the dip angle of the fault zone is proposed. The independent variables are substituted into the formula for fitting, and the correlation coefficient R is used to determine the result. 2 The rationality of the prediction formula is evaluated, and finally the parameters of the prediction formula are obtained.

2. The method for predicting blasting vibration considering the influence of fault zone dip angle according to claim 1, characterized in that, The PLASTIC_KINEMATIC model is used for rock mass and fault zones in the numerical model; the physical and mechanical parameters include material density, Young's modulus, Poisson's ratio, yield strength, tangent modulus and hardening coefficient.

3. The method for predicting blasting vibration considering the influence of fault zone dip angle according to claim 1, characterized in that, The boundary conditions of the numerical model include non-reflective boundaries and free boundaries. The non-reflective boundaries are set using the keyword BOUNDARY_NON_REFLECTING. Except for the free boundaries, all other surfaces are set as non-reflective boundaries.

4. The method for predicting blasting vibration considering the influence of fault zone dip angle according to claim 1, characterized in that, When the explosive charge is coupled to the borehole wall based on the detonation wave theory, it is in complete contact with the borehole wall, and the peak pressure of the blast load on the borehole wall is... P 0 can be calculated using the following formula: in, ρ 0 represents the density of the explosive (unit: kg / m³). 3 ); V D The detonation velocity of the explosive is expressed in m / s. γ The expansion adiabatic index of the detonation products.

5. The method for predicting blasting vibration considering the influence of fault dip angle according to claim 1, characterized in that, The time history curve of the blast load on the borehole wall is of the double exponential decay type, which can be expressed by the following formula: in, P 0 represents the peak pressure of the blasting load; t represents the duration of the blasting load (in seconds); t0 represents the rise time of the blasting load (in seconds). The blast load time history curve is defined by the keyword DEFINE_CURVE and applied by the keyword LOAD_SEGMENT_SET.

6. The method for predicting blasting vibration considering the influence of fault zone dip angle according to claim 1, characterized in that, The prediction formula for the amplified blasting vibration zone considering the fault dip angle is expressed as follows: Wherein, PPV is the peak velocity of a particle (unit: cm / s); k is a coefficient related to the blasting site conditions; Q is the amount of explosive used in a single blast (unit: kg); R is the distance from the blast center (unit: m); θ is the dip angle of the fault zone (unit: °); α and β are the attenuation coefficients corresponding to the dip angle of the fault zone and the amount of explosive used, respectively.

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