A method for determining the safety factor of rock blasting vibration based on particle vibration velocity

Abstract

The present invention provides a method for determining the rock blasting vibration safety factor based on the particle vibration velocity, and relates to the technical field of engineering blasting. The method first monitors the vibration velocity of the particle during on-site blasting to obtain the maximum vibration acceleration of the particle; and obtains the wave velocity of the rock mass and the static physical and mechanical parameters of the rock; then performs rock mass quality classification and estimates the static mechanical parameters of the rock mass; calculates the dynamic strain tensor of the rock mass, the dynamic strain rate of the rock mass and the dynamic uniaxial tensile strength of the rock mass; calculates the minimum dynamic principal stress of the rock mass based on the elastic constitutive model; and finally, according to the rock mass tensile strength theory, selects the maximum value of the minimum dynamic principal stress of the rock mass and the dynamic uniaxial tensile strength of the rock mass to calculate the blasting vibration safety factor. The method is based on the principle of mechanics and comprehensively considers the physical and mechanical parameters of the characteristic protection object. It can quantitatively describe the influence of blasting vibration on the specific protection object and determine the actual blasting vibration limit and safety factor of the specific protection object.

Description

Technical Field

[0001] The invention relates to the technical field of engineering blasting, and in particular to a method for determining a rock mass blasting vibration safety factor based on particle vibration velocity. Background Art

[0002] As an economical and efficient means of rock breaking, engineering blasting technology is widely used in mining, hydropower engineering construction, building (structure) demolition, urban underground space development and utilization, underwater reef blasting and dredging, etc. Blasting vibration is recognized as the most serious harmful effect of blasting. If it is not properly controlled, it will have a certain degree of impact on the surrounding structures. In severe cases, it will cause instability and damage to the structures, and then cause major safety accidents. Therefore, how to accurately evaluate the impact of blasting vibration on structures is of great significance for optimizing blasting excavation plans.

[0003] At present, the particle peak vibration velocity (PPV), particle peak vibration acceleration (PPA) and blasting vibration frequency are mainly used as the main parameters of blasting vibration safety control standards at home and abroad, but these parameters cannot directly establish the relationship between blasting vibration and instability and destruction of protected objects. In addition, the blasting vibration safety criteria at home and abroad generally give the corresponding safe allowable vibration velocity according to the category of protected objects, and do not give specific safety criteria for specific protected objects, which results in certain subjectivity and inapplicability in actual use. The essence of blasting vibration is the stress (strain) wave propagating in the medium. If the blasting vibration can be described by the dynamic strain and stress at the monitoring position, the blasting damage or the influence of blasting vibration can be evaluated according to the strength criterion, and then the actual blasting vibration limit and safety factor of the specific protected object can be determined. Therefore, a simple and practical method is needed to determine the actual blasting vibration limit and safety factor of a specific protected object based on the on-site blasting vibration monitoring results, rock mass mechanical parameters, and rock strength criteria (such as tensile strength criteria or Mohr-Coulomb strength criteria, etc.). Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a method for determining the rock blasting vibration safety factor based on particle vibration velocity in view of the above-mentioned deficiencies in the prior art.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for determining the rock blasting vibration safety factor based on the particle vibration velocity, the main steps of the method are as follows:

[0006] Step 1: Monitor the vibration velocity of the blasting mass point on site, and perform differential calculation on the monitoring result of the vibration velocity of the mass point to obtain the maximum vibration acceleration of the mass point;

[0007] Step 2: Conduct on-site rock mass wave velocity test and indoor rock mechanics test to obtain rock mass wave velocity and rock static physical and mechanical parameters;

[0008] Step 3: Classify the rock mass quality and estimate the rock mass static mechanical parameters based on the on-site engineering geological survey results and the rock static physical and mechanical parameters;

[0009] Rock mass quality is classified according to the rock mass geomechanical classification index value RMR standard and the static mechanical parameters of rock mass are estimated based on the Hoek-Brown strength criterion;

[0010] Step 4: Calculate the dynamic strain tensor of the rock mass based on the on-site rock mass wave velocity test results and the particle vibration velocity monitoring results;

[0011] The dynamic strain tensor of the rock mass calculated based on the on-site rock mass wave velocity test results and the particle vibration velocity monitoring results is:

[0012]

[0013] in, is the dynamic strain tensor of rock mass, , and They are the particle vibration velocities monitored on site and the particle vibration velocities at , and The components in three directions, and They are the propagation velocities of longitudinal waves and shear waves obtained from on-site rock mass wave velocity tests.

[0014] Step 5: Calculate the dynamic strain rate of the rock mass based on the on-site rock mass wave velocity test results and the particle vibration acceleration;

[0015] The formula for calculating the dynamic strain rate of rock mass based on the on-site rock mass wave velocity test results and particle vibration acceleration is:

[0016] in, is the dynamic strain rate of rock mass, is the maximum vibration acceleration of the particle.

[0017] Step 6: Calculate the dynamic uniaxial tensile strength of the rock mass based on the static uniaxial tensile strength of the rock mass and the dynamic strain rate of the rock mass estimated by the Hoek-Brown strength criterion;

[0018] The dynamic uniaxial tensile strength of the rock mass is calculated by the following relationship:

[0019] in, is the dynamic uniaxial tensile strength of rock mass, is the static uniaxial tensile strength of rock mass.

[0020] Step 7: Calculate the minimum dynamic principal stress of the rock mass based on the elastic constitutive model according to the physical and mechanical parameters of the rock mass and the dynamic strain tensor of the rock mass;

[0021] Step 8: According to the rock mass tensile strength theory, the maximum value of the minimum dynamic principal stress of the rock mass and the dynamic uniaxial tensile strength of the rock mass are selected to calculate the blasting vibration safety factor;

[0022] The blasting vibration safety factor is defined as the maximum value of the dynamic uniaxial tensile strength of the rock mass divided by the minimum dynamic principal stress of the rock mass.

[0023] The beneficial effects of the above technical solution are as follows: the present invention provides a method for determining the safety factor of rock blasting vibration based on particle vibration velocity, (1) based on the principle of mechanics, comprehensively considering the physical and mechanical parameters of the characteristic protection object, can quantitatively describe the impact of blasting vibration on the specific protection object, determine the actual blasting vibration limit and safety factor of the specific protection object, and overcome the subjectivity and inapplicability of traditional blasting vibration safety criteria in actual use. (2) It provides a method for quantifying blasting vibration from the perspective of strain and stress, and provides the relationship between blasting vibration and rock mechanics. This relationship can provide meaningful guidance for blasting vibration measurement, blasting damage control and rock dynamic strength evaluation. (3) The principle and calculation formula of this method are simple and easy to calculate and program. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A flow chart of a method for determining a rock blasting vibration safety factor based on particle vibration velocity provided by an embodiment of the present invention;

[0025] Figure 2 The on-site blasting particle vibration velocity monitoring result provided by the embodiment of the present invention;

[0026] Figure 3 The calculation result of the vibration acceleration of the particle point during on-site blasting provided by the embodiment of the present invention;

[0027] Figure 4 The calculation result of the dynamic principal strain tensor provided by the embodiment of the present invention, wherein (a) is the axial dynamic principal strain, (b) is the radial dynamic principal strain, and (c) is the vertical dynamic principal strain;

[0028] Figure 5 The minimum dynamic principal stress calculation result provided by the embodiment of the present invention. DETAILED DESCRIPTION

[0029] The specific implementation of the present invention is further described in detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0030] This embodiment takes an open-pit metal mine as an example, and adopts the rock blasting vibration safety factor determination method based on particle vibration velocity of the present invention to determine the slope blasting vibration safety factor of the mine.

[0031] In this embodiment, a method for determining the rock blasting vibration safety factor based on particle vibration velocity is provided. Figure 1 As shown, the following steps are included:

[0032] Step 1: Conduct on-site blasting vibration monitoring; the on-site blasting vibration monitoring is particle vibration velocity monitoring; and perform differential operation on the particle vibration velocity monitoring result to obtain the maximum vibration acceleration of the particle;

[0033] In this embodiment, the TC-4850-3 three-channel blasting vibration meter is used to monitor the blasting vibration on site in the open-pit metal mine. The vibration meter includes a three-axis vibration velocity sensor for monitoring the vibration velocity of the particle point on site. The on-site monitoring results are as follows: Figure 2 As shown; then the particle vibration velocity curve is differentiated using matlab software to obtain the particle vibration acceleration. The result is as follows Figure 3 As shown;

[0034] Step 2: Conduct on-site rock mass wave velocity test and indoor rock mechanics test to obtain rock mass wave velocity and rock static physical and mechanical parameters;

[0035] In this embodiment, the obtained rock mass wave velocity and some static physical and mechanical parameters of the rock are shown in Table 1;

[0036] Table 1 Statistics of rock mechanics experimental parameters

[0037]

[0038] Step 3: Classify rock mass quality and estimate rock mass mechanical parameters based on on-site engineering geological survey results and rock physical and mechanical parameters;

[0039] In this embodiment, the rock mass quality is classified according to the standard of rock mass geomechanics (CSIR) classification index value RMR (Rock Mass Rating) and the rock mass mechanical parameters are estimated based on the Hoek-Brown strength criterion. The rock mass quality classification results are shown in Table 2, and the rock mass mechanical parameter estimation results are shown in Table 3;

[0040] Table 2 Statistical table of rock mass geomechanics (RMR) classification calculation

[0041]

[0042] Table 3 Estimation of rock mass mechanical parameters

[0043]

[0044] Step 4: Calculate the dynamic strain tensor of the rock mass based on the on-site rock mass wave velocity test results and the particle vibration velocity monitoring results;

[0045] The dynamic strain tensor of the rock mass calculated based on the on-site rock mass wave velocity test results and the particle vibration velocity monitoring results is:

[0046]

[0047] in, is the dynamic strain tensor of rock mass, , and They are the particle vibration velocities monitored on site and the particle vibration velocities at , and The components in three directions, and They are the propagation velocities of longitudinal waves and shear waves obtained from on-site rock mass wave velocity tests.

[0048] In this embodiment, according to the on-site rock mass wave velocity test results and the particle vibration velocity monitoring results, the dynamic strain tensor of the rock mass is calculated and converted into the dynamic principal strain tensor of the rock mass. The conversion result is as follows: Figure 4 As shown;

[0049] Step 5: Calculate the dynamic strain rate of the rock mass based on the on-site rock mass wave velocity test results and the particle vibration acceleration;

[0050] The formula for calculating the dynamic strain rate of rock mass based on the on-site rock mass wave velocity test results and particle vibration acceleration is:

[0051]

[0052] in, is the dynamic strain rate of rock mass, is the maximum vibration acceleration of the particle obtained in step 1;

[0053] In this embodiment, based on the calculation results of the on-site particle vibration acceleration, it can be known that the maximum particle vibration acceleration =27.2712m / s 2 , so the dynamic strain rate of the rock mass can be calculated as: ;

[0054] Step 6: Calculate the dynamic uniaxial tensile strength of the rock mass based on the static uniaxial tensile strength of the rock mass and the dynamic strain rate of the rock mass;

[0055] The dynamic uniaxial tensile strength of the rock mass is calculated by the following relationship:

[0056] in, is the dynamic uniaxial tensile strength of rock mass (MPa), is the static uniaxial tensile strength of rock mass (MPa).

[0057] In this embodiment, since the dynamic strain rate of the rock mass is small, the strength of the rock mass is basically not affected by the strain rate, and the dynamic uniaxial tensile strength of the rock mass can be approximated by the static uniaxial tensile strength of the rock mass, that is, ;

[0058] Step 7: According to the physical and mechanical parameters of the rock mass and the dynamic strain tensor of the rock mass, the minimum dynamic principal stress of the rock mass is calculated based on the elastic constitutive model; in this embodiment, the minimum dynamic principal stress of the rock mass is calculated based on the rock mass elastic modulus of 13.93 GPa, Poisson's ratio of 0.29 and the dynamic strain tensor of the rock mass. The calculation result is as follows: Figure 5 As shown;

[0059] Step 8: According to the rock mass tensile strength theory, the maximum value of the minimum dynamic principal stress of the rock mass and the dynamic uniaxial tensile strength of the rock mass are selected to calculate the blasting vibration safety factor;

[0060] In this embodiment, according to the calculation results of the minimum dynamic principal stress of the rock mass, the maximum value of the minimum dynamic principal stress of the rock mass is 0.145625708MPa, so the blasting vibration safety factor is .

[0061] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope defined by the claims of the present invention.

Claims

1. A method for determining the rock blasting vibration safety factor based on particle vibration velocity, characterized in that: The following steps are involved: Step 1: Monitor the vibration velocity of the blasting mass point on site and calculate the maximum vibration acceleration of the mass point; Step 2: Obtain rock mass wave velocity and rock static physical and mechanical parameters; Step 3: Classify the rock mass quality and estimate the rock mass static mechanical parameters based on the on-site engineering geological survey results and the rock static physical and mechanical parameters; Step 4: Calculate the dynamic strain tensor of the rock mass based on the on-site rock mass wave velocity test results and the particle vibration velocity monitoring results; The dynamic strain tensor of the rock mass calculated based on the on-site rock mass wave velocity test results and the particle vibration velocity monitoring results is: Among them, ε(t) is the dynamic strain tensor of the rock mass, v1(t), v2(t) and v3(t) are the components of the particle vibration velocity in the x1, x2 and x3 directions respectively obtained by on-site particle vibration velocity monitoring, and c p and c s are the propagation velocities of longitudinal waves and transverse waves obtained from the on-site rock mass wave velocity test; Step 5: Calculate the dynamic strain rate of the rock mass based on the on-site rock mass wave velocity test results and the particle vibration acceleration; The formula for calculating the dynamic strain rate of rock mass based on the on-site rock mass wave velocity test results and particle vibration acceleration is: Among them, ε ′ is the dynamic strain rate of rock mass, is the maximum vibration acceleration of the particle; Step 6: Calculate the dynamic uniaxial tensile strength of the rock mass based on the static uniaxial tensile strength of the rock mass and the dynamic strain rate of the rock mass; The dynamic uniaxial tensile strength of the rock mass is calculated by the following relationship: s td =s t (e ′ ) 0.33 Among them, is σ td is the dynamic uniaxial tensile strength of rock mass, σ t is the static uniaxial tensile strength of the rock mass; Step 7: Calculate the minimum dynamic principal stress of the rock mass based on the elastic constitutive model according to the physical and mechanical parameters of the rock mass and the dynamic strain tensor of the rock mass; Step 8: According to the rock mass tensile strength theory, the maximum value of the minimum dynamic principal stress of the rock mass and the dynamic uniaxial tensile strength of the rock mass are selected to calculate the blasting vibration safety factor; The blasting vibration safety factor is defined as the maximum value of the dynamic uniaxial tensile strength of the rock mass divided by the minimum dynamic principal stress of the rock mass.

2. The method for determining the rock blasting vibration safety factor based on particle vibration velocity according to claim 1 is characterized in that: The step 2 is to conduct on-site rock mass wave velocity test and indoor rock mechanics test to obtain rock mass wave velocity and rock static physical and mechanical parameters.

3. The method for determining the rock blasting vibration safety factor based on particle vibration velocity according to claim 2, characterized in that: The step 3 classifies the rock mass quality according to the rock mass geomechanical classification index value RMR standard and estimates the static mechanical parameters of the rock mass based on the Hoek-Brown strength criterion.

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