CN117131340A - Layered slope blasting flyrock and vibration secondary disaster prevention and control method - Google Patents

Abstract

The invention provides a method for preventing and controlling a layered slope blasting flyrock and a vibration secondary disaster, which belongs to the technical field of slope blasting, and comprises the following steps: the method comprises the steps of analyzing the dimension of impact factors of the blasting flyrock, analyzing the flight process of the blasting flyrock, collecting data on a blasting construction site, processing the data, determining the maximum flight distance and the average flight distance of the blasting flyrock, and setting a safety distance. The invention applies dimension analysis to each influencing factor of the initial velocity of blasting flying stone throwing, thereby determining the dimensionless function form between the initial velocity and each factor. And then, determining the functional relation between the maximum flight distance and 3 parameters (unit consumption Q, single hole loading quantity Q and minimum resistance line W) of blasting through flight of the flyrock under the condition of neglecting air resistance and gravity, namely a throwing distance prediction formula of the blasting flyrock, and collecting and counting the maximum distance data of the throwing of the flyrock in time after blasting operation.

Description

Layered slope blasting flyrock and vibration secondary disaster prevention and control method

Technical Field

The invention relates to the technical field of side slope blasting, in particular to a method for preventing and controlling a layered side slope blasting flyrock and a vibration secondary disaster.

Background

Along with the rapid development of national economy and the scale expansion of industrial production, more and more building construction occasions need to adopt a blasting method to economically and efficiently finish mining operation, and the rock drilling blasting has the advantages of high efficiency, short time and the like, so that the rock drilling blasting has extremely wide application in mining, particularly in the excavation engineering of traffic facilities such as roadbeds, pile foundations, tunnels and the like which are frequently located in remote deep mountain areas. The blasting construction method has the characteristics of low construction cost, high operation efficiency and the like, so that the blasting construction method is widely applied to the construction of various foundation industries, and immeasurable economic benefit and social benefit are brought at the same time, and the blasting excavation method still occupies an important position in the rock excavation field in a certain period in the future. The explosion rock drilling and the explosion excavation bring convenience to engineering and simultaneously generate damages such as explosion vibration, explosion air shock wave, explosion noise, explosion smoke dust, explosion flying stone and the like. The hazards of such blasting often affect or even destroy surrounding buildings and production equipment, especially life threatening personnel. Therefore, in the practical blasting engineering, relevant safety protection measures, such as setting safety guard lines, covering safety protectors on facilities and the like, should be formulated and adopted, so that the construction is most beneficial under the condition of reducing or avoiding blasting hazard as much as possible. When the explosive package explodes in the rock and soil, a part of energy is used for destroying and throwing the medium so as to meet engineering requirements, but in the energy generated after the explosive explosion, most of energy acts on the medium around the blast hole in the modes of heat energy, impact wave energy and vibration wave energy to disturb the rock mass or structure around the blast hole, so that the rock mass and the structure are damaged or even destroyed. The energy released by the explosion of the explosive can be used for achieving various engineering purposes, but at the same time, the explosion products bring about non-negligible harmful effects and certain damages to the surrounding environment. Among the numerous hazards presented by blasting construction, blasting flyrock is one of its major hazards. The energy generated after the explosion of the explosive acts on the broken rock mass, so that the broken rock mass has a large flying initial speed, and the flying stone is thrown to the periphery after the initial speed is obtained, so that the controllability is very low, and the surrounding buildings, equipment and personnel are often damaged and injured.

Because China is a country with mountainous regions and hills, and because traffic facilities such as railways, highways and the like are far away from urban downtown areas in many times, most of excavation projects are located in remote mountain areas. Despite the variety of blasting modes, the generation of blasting flying stones and the hazards caused by the blasting flying stones are unavoidable. Therefore, a method for preventing and controlling the blasting flystones and the vibration secondary disasters of the layered slope is needed to be designed.

Disclosure of Invention

The invention aims to provide a layered side slope blasting flyrock and a vibration secondary disaster prevention and control method, which solves the technical problems that the existing method is low in controllability and can often cause damage and casualties to surrounding buildings, equipment and personnel after the initial blasting flyrock speed is obtained.

In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:

a method for preventing and controlling a layered slope blasting flyrock and a vibration secondary disaster comprises the following steps:

step 1: analyzing the dimension of blasting flying stone influence factors;

step 2: analyzing the flying process of the blasting flying stone;

step 3: data acquisition of a blasting construction site;

step 4: and processing the data, determining the maximum flight distance and the average flight distance of the blasting flying stone, and setting a safety distance.

Further, the specific process of the step 1 is as follows:

after the explosive is detonated in the blast hole, the rock medium is destroyed and comprises two processes, wherein the first process is the impact action of the explosion shock wave on the rock medium, the rock medium is crushed after being instantaneously impacted and compressed and propagates along with the continuous propagation of the shock wave to expand cracks to form stone blocks, and the second process is the expansion action of the explosion gas product, the generated expansion thrust is far higher than the resistance of the rock medium, so that rock particles can move, and the moving speed of the rock particles can be increased sharply when the rock particles reach the direction of small resistance in the moving process of the rock particles, and at the moment, the broken stone blocks are easy to throw outwards, namely the explosion flystones;

the blasting process from the generation of the flying stone to the throwing of the explosive after the detonation is initiated is divided into two parts, the blasting flying stone is set to be thrown at a high speed, the influence of gravity and air resistance of the flying stone is ignored, the throwing initial speed of the blasting flying stone is simplified to be related to parameters of the explosive, the blasting and the rock mass only, and influence factors including the parameters of the explosive, the blasting parameters and the rock mass are primarily determined, wherein the parameters of the explosive includeDetonation velocity D, specific energy E _e And the expansion coefficient gamma of explosive gas, the explosion parameters comprise unit consumption Q, single-hole loading Q, minimum resistance line W and aperture d, and the rock mass parameters comprise tensile strength sigma _t Compressive Strength sigma _c Shear strength sigma _t And a density ρ;

after the explosive in the blast hole is detonated, energy is transmitted to the stone block due to the combined action of explosion shock waves and explosive gas products, the stone block becomes blasting flying stone with initial speed to be thrown out, and the relation between the initial speed and influencing factors can be converted into a dimensionless form to be continuously analyzed:

v ₀ ＝f(q，d，γ，σ _t ，σ _c ，σ _t ，ρ，Q，D，E _e ，W)

q, D, W is chosen as the basic dimension, whereby the dimensionless form of the basic physical quantity is determined, 8 independent variables:

π ₃ ＝γ；/>

wherein pi represents a dimensionless quantity, pi ₁ -π ₈ A dimensionless formula for the initial velocity of the blasted flyrock when thrown can be obtained representing the 8 independent dimensions:

when blasting belonging to a certain engineering project, the same explosive is used, and the change of geological features in the range of the blasting operation site is limited, 6 physical quantities can be regarded as unchanged, and 6 physical quantities are E ₁ 、γ、σ _t 、σ _c 、σ _τ ρyou, remove 6 physical quantities that do not change, leave only 5 physical quantities, 5 physical quantities are the detonation velocity D, the unit consumption Q, the single hole charge quantity Q, the minimum resistance line W and the aperture D, then simplify the above formula:

performing left-right movement to determine an initial velocity v of blasting flying stone ₀ Is a functional form of:

in the same blasting engineering, the diameter of the drilling hole and the detonation velocity D of the explosive are kept unchanged, so that the simplification treatment can be continued to further obtain an initial velocity v of blasting flyrock ₀ Is a functional form of:

further, the specific process of the step 2 is as follows:

the calculation formula of the furthest distance to which the blasting flyrock is thrown can be obtained by analyzing the condition that the blasting flyrock ignores air resistance and gravity:

wherein: r is R _f V0 is the initial speed of the blasting flyrock, g is the gravity acceleration, and alpha is the blasting flyrock throwing angle;

obviously, the rock thrown at α=45° flies the furthest:

the initial velocity v of the blasting flyrock ₀ The combination of the functional expression of (2) and the functional expression of the maximum distance reached by the throwing of the blasting flyrock is obtained:

approximation of this in the form of a power function yields:

wherein: K. beta is a coefficient to be determined;

in a certain blasting operation, if knowing the unit consumption Q, the single hole loading Q and the minimum resistance line W of blasting, a prediction can be made in advance for the flight distance of the blasted flyrock and related precautionary measures can be made to reduce or avoid loss and casualties, so that the values of the coefficients K and β to be determined need to be further determined.

Further, the specific process of the step 3 is as follows:

according to the actual minimum resistance line W, the actual maximum single-hole loading quantity Q and the maximum flying stone distance R of each excavation cycle _fmax And collecting and counting the site data of the blasting flying stone throwing distance.

Further, the specific process of step 4 is as follows:

there is an error in collecting the data so that only a relative range can be provided for the prediction of the flying stone distance, and the data is summed to averageAs the minimum of the range, and taking the furthest distance R of the data from which the stone is thrown _fmax As the maximum value of this range;

setting a prediction formula model, wherein the change value of an independent variable in the prediction formula model is not large, and taking the logarithm of the independent variable and the dependent variable respectively, so that the original blasting flying stone flight distance prediction formula model is as follows:

taking the logarithm of two sides:

aiming at the acquired data, the specific charge Q, the minimum resistance line W and the maximum loading Q of a single hole of each group of explosives are calculated to obtainThe values are then summed up separately to average +.>The maximum value in each group of data is then taken as the maximum distance value R of the flying stone _fmax ；

Average distance of flying stone in logarithmic phaseValue and->Value, by blasting flyrock distance prediction formula model +.>Fitting is carried out to obtain fitting data;

average distance of flying stone in logarithmic phaseValue and->Value, by blasting flyrock distance prediction formula model +.>Fitting is carried out to obtain fitting data.

Due to the adoption of the technical scheme, the invention has the following beneficial effects:

the invention applies dimension analysis to each influencing factor of the initial velocity of blasting flying stone throwing, thereby determining the dimensionless function form between the initial velocity and each factor. And then, determining a functional relation between the maximum flight distance and 3 parameters (unit consumption Q, single hole loading quantity Q and minimum resistance line W) of blasting through flight of the flyrock under the condition of neglecting air resistance and gravity, namely a throwing distance prediction formula of the blasting flyrock, collecting and counting the maximum distance data of the throwing of the flyrock in time after blasting operation, and finally analyzing and fitting test data to obtain a parameter fitting value, thereby determining a blasting flyrock throwing distance prediction calculation formula and determining the blasting safety distance in time.

Drawings

FIG. 1 is a linear fit of the maximum distance of flying stone of the present invention;

figure 2 is a linear fit of the maximum distance of flying stone of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be further described in detail below by referring to the accompanying drawings and by illustrating preferred embodiments. It should be noted, however, that many of the details set forth in the description are merely provided to provide a thorough understanding of one or more aspects of the invention, and that these aspects of the invention may be practiced without these specific details.

A method for preventing and controlling a layered slope blasting flyrock and a vibration secondary disaster comprises the following steps:

step 1:

(1) Measurement of physical quantity

A measurement of a physical quantity is usually compared with a similar physical quantity, and when the two physical quantities are compared, the selected similar physical quantity is often used as a basic unit. For example, when we need to measure the length L of an object encountered, we first know the length L of the same kind of object ₀ As a unit, then comparing the two to obtain the magnitude of the thing, L, and recording the relationship as l=ll ₀ 。

Thus, for a certain physical quantity a, taking a certain similar object as a unit U, and assuming that the magnitude obtained by comparing the two measures is a, the physical quantity a is:

A＝aU(a＝a ₀ ±Δa) (1)

wherein: a-the actual magnitude; Δa—error.

(2) Dimension of physical quantity

For a matter, we discuss and study it, and often refer to some physical quantity (such as time, quality, etc.) related to it, and we define each physical quantity with different characteristics as representing a different "dimension" by itself. The dimensions of a physical quantity are often expressed as a formula consisting of selected individual basic quantities, which represent the nature or class to which they belong, irrespective of their size, so that these dimensions can be divided into two classes: basic dimensions and derived dimensions. Thus, the dimension of a physical quantity is a functional expression that is the product of the powers of the individual basic quantities, i.e., the dimension. According to the description of the international system of units, it is agreed that seven basic physical quantities of length, mass, time, current, thermodynamic temperature, quantity of substance and luminous intensity are taken as basic dimensions, and their obtained dimensions are denoted as L, M, T, I, Q, N, J.

Therefore, the dimension [ A ] of any one of the physical quantities A can be expressed as:

the basic dimensions are relatively independent and the other dimensions cannot be represented. Therefore, the dimension of each physical quantity is fixed, but there may be a plurality of units of the physical quantity. At the same time, some physical quantities are not steel-filled, but have units, such as angles.

(3) Dimensionless dimension

In many cases, all indices of the basic dimensions contained in the dimensional expression may be zero, and the amount by which such indices are all zero is called a dimensionless amount. In practice, some amounts are dimensionless, such as pi, e, etc., where [ pi ] =1, [ e ] =1. We can dimensionless the physical quantity with dimension. Dimensionless is a mathematical variation method for eliminating the influence of the dimension of related variables on the analysis of the result, namely, the variables are obtained by multiplying the indexes of basic parameters (such as elastic modulus, yield strength and dimension of materials) describing the characteristics of the problems, so that the dimension is eliminated. Therefore, the dimensionless treatment does not eliminate its own characteristics. If the basic dimension is also the basic dimension, the basic dimension can be divided by another basic parameter; when the dimension is derived, the dimension index of the combined physical quantity can be zero by combining a plurality of basic parameters containing different basic dimensions with the multiplication and division thereof. The description of the dimensionless number [ A ] is:

[A]＝L ⁰ M ⁰ T ⁰ ＝1 (3)

the dimensionless scale can be represented by a quotient of two physical quantities with the same dimension, and can be obtained by combining products and quotients of different physical quantities with several dimensions. The basic steps of dimensionless implementation are as follows: first, a basic physical quantity is selected reasonably from physical quantities capable of representing the characteristics of the material, and the basic quantity is fixed and cannot be changed; then, each physical quantity is subjected to dimensionless treatment and replaces the physical quantity in the original function, but note that the rule represented by the replaced physical quantity is not changed. The dimension analysis is a measure for analyzing and researching the relation between the physical quantities by ensuring the dimension consistency of the two sides of the function equal sign. Meanwhile, the dimension of the physical quantity indicates a multiple of the change in the magnitude of each physical quantity due to the unit change of the selected basic quantity.

Step 2: basic principle and principle of dimension analysis

(1) For some kind of problem involved, if n independent variables (a ₁ ，a ₂ ，…a _n ) The dependent variable a can be taken as a function of these n independent variables, namely:

a＝f(a ₁ ,a ₂ ,…a _k ,a _k+1 ,…a _n ) (4)

of the n independent variables included in the problem, k basic quantities (a) having independent dimensions are preferentially extracted ₁ ，a ₂ ，...a _k ) Their dimensions are A ₁ A ₂ ...A _k The method comprises the steps of carrying out a first treatment on the surface of the The remaining n-k independent variables and dependent variable a are derived quantities, so the derived quantities can be expressed as power functions of the selected k basic quantities, respectively:

……

using the selected k basic quantities a ₁ ，a ₂ …a _k As a unit system for studying this problem, and using them to measure the individual quantities in the functional relation, the measured quantities are all dimensionless pure numbers, which necessarily satisfy the functional relation:

depending on the nature of the dimension, formula (6) can be written as:

π＝f( _π1 ，π ₂ ，…π _n-k ) (7)

if the expression (7) is transformed, and the expression form used by the expression is changed from explicit to implicit, the dependent variable and the independent variable of the function expression are all converted into variables, and then another functional relationship is obtained:

f(π ₁ ,π ₂ ，…π _n-k )＝0 (8)

at this time, the contents of pi theorem can be summarized as follows: if a question is studied, in which there are N variables, from which k basic quantities are then selected, (N-k) dimensionless variables are necessary, and the functional relationship they constitute is deterministic.

(2) Principle of dimensional uniformity

When researching a certain problem, if a mathematical function expression is used to express a certain physical law, the consistency of the dimension of the equal sign of the expression must be ensured at the two ends of the equal sign of the expression, namely the uniformity principle of the dimension. If each term in the function expression is the same dimension, the function expression is homogeneous in dimension, and the addition and subtraction operation can be performed on the function expression. By this principle we can define a criterion on the dimension analysis.

Is provided with m physical quantities q ₁ q ₂ … q _m Satisfy a certain law: f (q) ₁ ，q ₂ ，…q _m ) =0, yet X ₁ ,X ₂ ,…X _n Is the basic dimension (n<m)。

Q is _j The dimension of (2) can be expressed asAnd matrix a= (a) _ij ) n, m are referred to as dimension matrices.

Assuming that the matrix a has rank ranka=r, the homogeneous system of equations ay=0 is satisfied, (Y is an m-dimensional vector), and the (m-r) basic solutions of the system of equations areAvailable->Is (m-r) independent dimensionless numbers, and has a certain unknown function satisfying F (pi) ₁ ，π ₂ ，…，π _m-r ) =0 and f (q ₁ ，q ₂ ，…，q _m ) Equivalent =0.

Step 3: dimensional step process

(1) Determination of the relationship

For a certain research object, comprehensively analyzing the research object, finding out each influence factor related to the research object, selecting main influence factors from the influence factors, avoiding complicating the research object as much as possible, and finally marking the selected factors as a ₁ ，a ₂ ，…a _n And gives the functional relation between the individual physical quantities:

f(a ₁ ,a ₂ ,…ak,a _k+1 ,…a _n )＝0 (9)

(2) Determination of the basis weight

Among the individual influencing factors (i.e., physical quantities, the number of which is assumed to be n) related to the subject, k influencing factors are selected as basic physical quantities of the study, and these basic physical quantities are denoted as a ₁ ，a ₂ ，…，a _k (k.ltoreq.n) whose dimensions are A respectively ₁ ，A ₂ ，…，A _k Thereby, can obtain:

taking the logarithm of both the left and right variations of equation (10) at the same time yields:

1n[a]＝m ₁ lnA ₁ +m ₂ lnA ₃ +…+m _k lnA _k (11)

by taking the equation (11) as the orthogonal basis vector of a certain k-dimensional space, the k basic physical quantities a selected can be known ₁ ，a ₂ ，…，a _k Is the vector ln [ a ]]Projection onto each basis vector. Therefore, the "dimension" of the physical quantity a can be expressed as:

ln[a]→(a ₁ ，a ₂ ，…a _k ) (12)

for example, k=3 is generally taken, and the dimension-independent base vector is assumed to be (a ₁ ，a ₂ ，a ₃ ) (including the dynamics basic dimension L, M, T), is available according to the relevant notations:

according to the theory of dimension analysis, the selected individual basic dimensions must be independent of each other, and they reach

(3) Determination of dimensionless terms

The selected basic variables can be combined with the rest of other physical quantities a _k+1 ，a _k+2 ，…，a _n The (n-k) dimensionless terms are composed and each of these components is labeled pi terms. Also, since pi is a non-dimensional quantity, it is possible to obtain:

other physical quantity a remaining _k+1 ，a _k+2 ，…，a _n The non-dimensional terms of the composition can be expressed as:

such as: we generally take the value k=3 and assume that its dimension independent basis vector is (a ₁ ,a ₂ ,a ₃ ) (including the kinetic basic dimensions L, M, T), is obtained according to the relevant formula:

(4) Determining dimensionless form

Taking the logarithm of two sides of the (18) at the same time to obtain:

ln A _k+j ＝a _1j ln A ₁ +a _2j ln A ₂ +…+a _kj ln A _k (j＝1，2，…，n) (19)

writing it in the form of component amounts, then:

and correspondingly adjusting the function expression obtained after dimension analysis to obtain a corresponding dimensionless equation, namely:

F(π ₁ ，π ₂ ，…，π _n-k )＝0 (21)

as can be seen from the equation (21), for the problem under investigation, since each physical quantity selected in the problem is subjected to a series of dimensional analyses, a dimensionless equation corresponding to the physical quantity can be obtained, that is, the physical quantities are related to each other in a certain relation. Therefore, the method can be used for researching and analyzing a certain problem by a dimension analysis method, and has important significance for knowing and grasping the relationship between the physical quantities corresponding to the influence factors.

Step 4: dimension analysis of blasting flyrock throwing rule

1. Dimensional analysis of blasting flyrock influencing factors

The explosion phenomenon is quite complex, and the whole explosion process can be roughly divided into a plurality of stages of detonation of explosive, propagation and expansion of explosion waves in a soil-rock medium, bulge and bulge, throwing and falling back and the like.

After the explosive is initiated in the blasthole, the rock medium is destroyed involving two processes. The first process is the impact of the explosion shock wave on the rock medium, the rock medium is crushed after being compressed by the instant impact and the crack is expanded along with the continuous propagation of the shock wave, so that the rock medium becomes a large number of stones; the second process is the expansion of the explosive gas product, which generates an expansion thrust that is much higher than the resistance of the rock medium, so that the rock particles will move to some extent, and during the movement of the rock particles, when they reach the direction of very low resistance, the movement speed of the rock particles will increase sharply. At this time, the broken stone blocks are easily thrown outwards, namely the blasting flyrock.

Therefore, it is not possible to analyze the blasting process from the creation of flying stones to the throwing of the explosive after the detonation through a theoretical tool in a reasonable and systematic way. In view of this complexity, we can split the whole process into two parts to make the analysis simpler.

Firstly, we can consider that the blasting flyrock is thrown out at a high speed, neglecting the influence of gravity and air resistance of the flyrock on the blasting flyrock, so that the initial throwing speed of the blasting flyrock can be simplified to be related to parameters of explosive, blasting and rock mass only, and various main influencing factors are primarily determined:

(1) parameters of the explosive: detonation velocity D, specific energy E _e The expansion coefficient gamma of the explosive gas;

(2) blasting parameters: unit consumption Q, single-hole drug loading quantity Q, minimum resistance line W and aperture d;

(3) rock parameters: tensile strength sigma _t Compressive Strength sigma _c Shear strength sigma _τ Density ρ.

The main relevant factors are analyzed by a dimension analysis method, L, M and T are determined to be 3 basic quantities, and each influencing factor and the initial flying stone velocity v are further determined ₀ As shown in the table:

table 1 shows the parameters and dimensions of the blasted flyrock

After the explosive in the blast hole is detonated, certain energy is transferred to the stone block due to the combined action of the explosion shock wave and the explosive gas product, so that the stone block becomes the blasting flying stone with initial speed and is thrown out. The relationship between the initial velocity and the various influencing factors can be converted into a dimensionless form for further analysis:

v ₀ ＝f(q，d，γ，σt，σ _c ，σ _τ ，ρ，Q，D，E _e ，W) (22)

we choose Q, D, W as the basic dimension among these 11 basic physical quantities, thereby determining the dimensionless form of each basic physical quantity, see 8 independent variables in formula (24):

π ₃ ＝γ；/>

thus, a dimensionless formula can be obtained for the initial velocity of the blasted flyrock as it is thrown:

according to practical experience in the conventional blasting operation, when the blasting operation belonging to a certain engineering project is performed, the same explosive is often adopted, and the change of geological characteristics of the blasting operation site is limited in a certain range. Therefore, some of the 12 basic physical quantities listed in the above table may be regarded as unchanged. Thus, after E is removed _e 、γ、σ _t 、σ _c 、σ _τ After 6 physical quantities above ρ, only 5 physical quantities (detonation velocity D, unit consumption Q, single hole charge quantity Q, minimum resistance line W and aperture D) are left, and the formula (24) can be continuously simplified to obtain a relational expression:

the left and right shift of the above can determine an initial velocity v of blasting flying stone ₀ Is a functional form of:

according to the actual field experience, the drilling diameter and the detonation velocity D of the explosive are always kept unchanged in the same blasting engineering, so that the formula (26) can be continuously simplified to further obtain an initial velocity v of the blasting flyrock ₀ Is a functional form of:

2. flying process of blasting flying stone

The condition that the blasting flyrock ignores air resistance and gravity is analyzed through a simple physical theory, and a calculation formula of the furthest distance of the blasting flyrock can be obtained:

wherein: r is R _f Blasting flying stone throw distance

v ₀ -initial velocity of blasting flyrock

g-gravity acceleration

Alpha-blasting flyrock throwing angle

Obviously, the rock thrown at α=45° flies the furthest:

the initial velocity v of the blasting flyrock ₀ The combination of the functional expression of (2) and the functional expression of the maximum distance reached by the throwing of the blasting flyrock is obtained:

approximation of this in the form of a power function yields:

wherein: K. beta is the coefficient of uncertainty.

According to the formula (31), if the unit consumption Q, the single hole loading Q and the minimum resistance line W of blasting are known in a certain blasting operation, a prediction can be made in advance on the flight distance of the blasted flyrock and related precautions can be made to reduce or avoid loss and casualties. Thus, the value of the predetermined coefficient K, β needs to be further determined.

The specific scheme is as follows: guangxi Yanlai tunnel and Rong Lian tunnel are constructed in Guangxi river basin city, tian Emei county, which is 6 standard projects from Nandina to TianEmei in the old high speed. The project has steep hillside, fluctuating topography, ravines, longitudinal and transverse directions, extremely complex geological conditions, weathered and broken rock mass and fragile ecological environment, wherein the total length 6300 m of the Yanlai tunnel is the longest tunnel under construction by Guangxi, the Rongli tunnel is positioned near the Rong Li of the old county, the total length 1201 m is a separated bidirectional four-lane tunnel.

The method mainly aims at a construction section of a Rong-Liu tunnel, performs blasting scheme design on road foundation excavation and tunnel excavation, timely collects and counts maximum distance data of flying stone throwing after blasting operation, and finally performs analysis and fitting treatment on test data to obtainK, beta fitting values of (2) to determine blasting flyrock throw distance predictionAnd (3) calculating a formula.

1. Data collection

In the actual engineering, the engineering progress, economic benefit and over-digging and under-digging caused by blasting are required to be considered, so that the actual minimum resistance line W, the hole depth L, the single-hole drug loading quantity Q and the design have certain deviation. This time using a # 2 rock emulsion explosive (2000 g/volume, phi 70mm x 40 cm).

The data are based on the actual minimum resistance line W, the actual maximum single-hole loading Q and the maximum flying stone distance R of each excavation cycle _fmax Collecting the statistical blasting flying stone throwing distance field data, and displaying the statistical blasting flying stone throwing distance field data in a table.

Table 2 shows statistics of the throw distance of blasting flying stone

/>

2. Data processing

For each group of data of blasting site statistics, firstly, reasonable analysis is carried out on the data. The factors influencing the flight distance of the blasting flyrock are numerous, the flyrock is scattered around by taking a blast hole as the center in the extremely short blasting time, but the flyrock is disordered and can be found irregularly. It is difficult to collect hundreds or thousands of sets of data in a certain blasting cycle, so that only limited data is reasonably analyzed at this time. Considering that there is some error in collecting data, only a relative range can be provided for the prediction of the flying stone distance, and in order to make this range more reasonable, the small groups of data are summed to averageAs the minimum value of the range, taking the furthest distance R of the rock being thrown in each group of data _fmax As the maximum value of this range.

Secondly, as the independent variable change value in the prediction formula model is not large, in order to better fit the related undetermined parameters, the data are required to be transformed so that the data can be reasonably analyzed by using the correlation theory, and therefore the independent variable and the dependent variable are respectively logarithmized. Then, the original blasting flyrock flight distance prediction formula model:

taking the logarithm of two sides:

for the collected data, firstly calculating the specific charge Q, the minimum resistance line W and the maximum loading quantity Q of a single hole of each group of explosive to obtain a Q value, and then respectively summing the flying distance data of the blasting flyrock to obtain the average thereofThe maximum value in each group of data is then taken as the maximum distance value R of the flying stone _fmax The results obtained after calculation are shown in the table.

Table 3 is data averaging

The data in the table is converted, namely, the log is processed, and log values can be obtained, and the result is as follows:

table 4 shows the data as a logarithm

Average distance of flying stone in logarithmic phaseValue and->Value, by blasting flyrock distance prediction formula model +.>Fitting was performed and the linear fitting results are shown in the x-bar graph. Wherein, the fitting value β=0.11032, k= 220.716, the fitting factor r2= 0.92065, and the fitting degree is satisfactory.

Average distance of flying stone in logarithmic phaseValue and->Value, by blasting flyrock distance prediction formula model +.>Fitting was performed and the results of the linear fitting are shown in the following figures. Wherein, the fitting value is beta=0.11274, K= 237.604, the fitting degree factor is R2= 0.93466, and the fitting degree is satisfactory.

The foregoing is merely a preferred embodiment of the present invention and it should be noted that modifications and adaptations to those skilled in the art may be made without departing from the principles of the present invention, which are intended to be comprehended within the scope of the present invention.

Claims (5)

1. A method for preventing and controlling a layered slope blasting flyrock and a vibration secondary disaster is characterized in that: the method comprises the following steps:

step 1: analyzing the dimension of blasting flying stone influence factors;

step 2: analyzing the flying process of the blasting flying stone;

step 3: data acquisition of a blasting construction site;

step 4: and processing the data, determining the maximum flight distance and the average flight distance of the blasting flying stone, and setting a safety distance.

2. The method for preventing and controlling the blasting flyrock and the vibration secondary disaster of the layered slope according to claim 1, which is characterized in that: the specific process of the step 1 is as follows:

after the explosive is detonated in the blast hole, the rock medium is destroyed and comprises two processes, wherein the first process is the impact action of the explosion shock wave on the rock medium, the rock medium is crushed after being instantaneously impacted and compressed and propagates along with the continuous propagation of the shock wave to expand cracks to form stone blocks, and the second process is the expansion action of the explosion gas product, the generated expansion thrust is far higher than the resistance of the rock medium, so that rock particles can move, and the moving speed of the rock particles can be increased sharply when the rock particles reach the direction of small resistance in the moving process of the rock particles, and at the moment, the broken stone blocks are easy to throw outwards, namely the explosion flystones;

setting the blasting process from the generation of the flying stone to the throwing of the flying stone after the explosive is detonated, dividing the whole process into two parts, setting the blasting flying stone to be thrown at a high speed, neglecting the influence of gravity and air resistance of the flying stone, simplifying the throwing initial speed of the blasting flying stone to be related to parameters of the explosive, the blasting and the rock mass only, and preliminarily determining influencing factors including the parameters of the explosive, the blasting parameters and the rock mass, wherein the parameters of the explosive comprise the blasting speed D and the specific energy E _e And the expansion coefficient gamma of explosive gas, the explosion parameters comprise unit consumption Q, single-hole loading Q, minimum resistance line W and aperture d, and the rock mass parameters comprise tensile strength sigma _t Compressive Strength sigma _c Shear strength sigma _τ And a density ρ;

after the explosive in the blast hole is detonated, energy is transmitted to the stone block due to the combined action of explosion shock waves and explosive gas products, the stone block becomes blasting flying stone with initial speed to be thrown out, and the relation between the initial speed and influencing factors can be converted into a dimensionless form to be continuously analyzed:

v ₀ ＝f(q，d，γ，σ _t ，σ _c ，σ _τ ，ρ，Q，D，E _e ，W)

q, D, W is chosen as the basic dimension, whereby the dimensionless form of the basic physical quantity is determined, 8 independent variables:

π ₃ ＝γ；/>

wherein pi represents a dimensionless quantity, pi ₁ -π ₈ A dimensionless formula for the initial velocity of the blasted flyrock when thrown can be obtained representing the 8 independent dimensions:

when blasting belonging to a certain engineering project, the same explosive is used, and the change of geological features in the range of the blasting operation site is limited, 6 physical quantities can be regarded as unchanged, and 6 physical quantities are E _e 、γ、σ _t 、σ _c 、σ _τ ρyou, remove 6 physical quantities that do not change, leave only 5 physical quantities, 5 physical quantities are the detonation velocity D, the unit consumption Q, the single hole charge quantity Q, the minimum resistance line W and the aperture D, then simplify the above formula:

performing left-right movement to determine an initial velocity v of blasting flying stone ₀ Is a functional form of:

in the same blasting engineering, the diameter of the drilling hole and the detonation velocity D of the explosive are kept unchanged, so that the simplification treatment can be continued to further obtain an initial velocity v of blasting flyrock ₀ Is a functional form of:

3. the method for preventing and controlling the blasting flyrock and the vibration secondary disaster of the layered slope according to claim 1, which is characterized in that: the specific process of the step 2 is as follows:

the calculation formula of the furthest distance to which the blasting flyrock is thrown can be obtained by analyzing the condition that the blasting flyrock ignores air resistance and gravity:

wherein: r is R _f To burst the flying stone throwing distance v ₀ The initial speed of the blasting flyrock is g, the gravity acceleration is g, and alpha is the blasting flyrock throwing angle;

obviously, the rock thrown at α=45° flies the furthest:

the initial velocity v of the blasting flyrock ₀ The combination of the functional expression of (2) and the functional expression of the maximum distance reached by the throwing of the blasting flyrock is obtained:

approximation of this in the form of a power function yields:

wherein: K. beta is a coefficient to be determined;

in a certain blasting operation, if knowing the unit consumption Q, the single hole loading Q and the minimum resistance line W of blasting, a prediction can be made in advance for the flight distance of the blasted flyrock and related precautionary measures can be made to reduce or avoid loss and casualties, so that the values of the coefficients K and β to be determined need to be further determined.

4. The method for preventing and controlling the blasting flyrock and the vibration secondary disaster of the layered slope according to claim 1, which is characterized in that: the specific process of the step 3 is as follows:

according to the actual minimum resistance line W, the actual maximum single-hole loading quantity Q and the maximum flying stone distance R of each excavation cycle _fmax And collecting and counting the site data of the blasting flying stone throwing distance.

5. The method for preventing and controlling the blasting flyrock and the vibration secondary disaster of the layered slope according to claim 1, which is characterized in that: the specific process of the step 4 is as follows:

there is an error in collecting the data so that only a relative range can be provided for the prediction of the flying stone distance, and the data is summed to averageAs the minimum of the range, and taking the furthest distance R of the data from which the stone is thrown _fmax As the maximum value of this range;

setting a prediction formula model, wherein the change value of an independent variable in the prediction formula model is not large, and taking the logarithm of the independent variable and the dependent variable respectively, so that the original blasting flying stone flight distance prediction formula model is as follows:

taking the logarithm of two sides:

aiming at the acquired data, the specific charge Q, the minimum resistance line W and the maximum loading Q of a single hole of each group of explosives are calculated to obtainThe values are then summed up separately to average +.>The maximum value in each group of data is then taken as the maximum distance value R of the flying stone _fmax ；

Average distance of flying stone in logarithmic phaseValue and->Value, by blasting flyrock distance prediction formula model +.>Fitting is carried out to obtain fitting data;

average distance of flying stone in logarithmic phaseValue and->Value, by blasting flyrock distance prediction formula model +.>Fitting is carried out to obtain fitting data.