CN104048567B - On cover the defining method of the boulder explosion pretreatment explosive specific charge under Rock Conditions - Google Patents

Abstract

The invention provides a method for determining the unit consumption of pretreatment explosives in boulder blasting under the condition of overlying rock and soil. The overlying rock and soil is determined by calculating the modified Swedish empirical formula Q=Q ₁ +Q ₂ +Q ₃ +Q ₄ The unit consumption of explosives pretreated by boulder blasting under the condition of , where Q is the unit consumption of the best explosives for on-site blasting; Q ₁ is the unit consumption of basic explosives, Q ₁ =k ₁ q ₁ ; Q ₂ is the water depth caused by the blast area above Pressure increase, Q ₂ =0.01h ₂ , h ₂ is the water pressure depth above the explosion zone; Q ₃ is the cover layer increment above the explosion zone, Q ₃ =k ₃ h ₃ , h ₃ is the thickness of the soft soil cover; Q ₄ is the rock expansion increment, Q ₄ =0.03h ₄ , h ₄ is the blasting step height. The present invention determines the pretreatment explosive unit consumption of boulder blasting under the condition of overlying rock and soil by amending the Swedish empirical formula, which is convenient for calculation, has small error between the obtained explosive unit consumption and the actual explosive unit consumption, and has high accuracy. The degree meets the relevant indicators and has strong applicability.

Description

Method for Determination of Unit Consumption of Pretreatment Explosives in Boulder Blasting Under Overlying Rock and Soil Conditions

technical field

The invention relates to the field of blasting, in particular to a method for determining the unit consumption of pretreatment explosives for boulder blasting under the condition of overlying rock and soil.

Background technique

Composite strata are widely distributed in South China. Spherical unweathered high-strength boulder groups in granite weathered soil in this type of stratum are technical difficulties often encountered in shield tunneling construction in South China (such as Guangzhou, Shenzhen, etc.). In order to ensure the smooth excavation of the shield machine, the use of ground drilling and blasting to pretreat high-strength boulders or bedrock protrusions is one of the most commonly used methods at present. This method has been popularized and applied in a large number of shield tunneling constructions, and Chinese patents have successively published a number of methods related to blasting pretreatment, such as the application method of underground obstacle blasting in shield tunneling construction (application number 200910047375.2), composite Blasting method for closed rock mass of stratum shield tunnel (application number is 201010173457.4), a treatment method for boulder group in dissolved ditch section of shield excavation (application number is 201110417722.3), a pile and wall type deep foundation pit support structure The processing method of large boulders (the application number is 201010280658.4), but none of them involve the method of determining the unit consumption of explosives for boulder blasting.

Different from other blasting requirements, the pretreatment of boulder blasting must design reasonable blasting parameters such as explosive unit consumption to ensure that the size of the boulder after blasting is less than 30cm, so as to meet the size of the opening of the shield machine cutter head and the size of the muck conveyed by the screw conveyor. Require. The empirical formula of explosive unit consumption commonly used in existing similar project blasting is as follows: (1) q _water = q _land + 0.01H _water + 0.02H _medium + 0.03H _ladder adopted by China's water conservancy system, wherein H _water represents water depth, and H _medium represents Explosive burial depth, H _ladder indicates the height of the ladder; (2) Japan Explosives Association adopts L _a ＝ H · C _a (water pressure correction); L _β ＝ H ₀ · C _β (overlying soil and rock correction), where H represents water depth , H ₀ represents the thickness of the overlying layer; (3) The Swedish formula is q=q ₁ +q ₂ +q ₃ +q ₄ , where q ₁ is the basic charge, which is 2 to 3 times that of general land bench blasting, For underwater vertical drilling, add another 10%; q ₂ is the water pressure increment above the explosion zone, q ₂ =0.01h ₂ , h ₂ is the water depth, in meters; q ₃ is the overburden increment above the explosion zone, q ₃ =0.02h ₃ , h ₃ is the thickness of the covering layer (silt or soil, sand), in meters; q ₄ is the rock expansion increment, q ₄ =0.03h, h is the height of the ladder, in meters; ( 4) "Engineering Blasting Practical Handbook" adopts Q=K·W _a ·H(1.45+0.45e ^-0.33(H0/w) ). The above four empirical formulas do not take into account the special technical requirements of 30cm blockage after blasting, they are all based on the requirements of conventional blasting as control indicators, and are quite different from the actual engineering application of boulder blasting pretreatment under overlying rock and soil conditions. . In the actual project of shield tunneling through boulder groups or bedrock protruding strata, the commonly used Swedish formula is generally used to initially estimate the unit consumption of explosives. To meet the technical standards of shield tunneling, it is usually necessary to determine the best blasting parameters such as the unit consumption of explosives through multiple on-site blasting tests, which is labor-intensive and low in work efficiency.

Therefore, it is of great significance to develop a method for determining the unit consumption of pretreatment explosives in boulder blasting under the condition of overlying rock and soil.

Contents of the invention

The purpose of the present invention is to provide a method for determining the unit consumption of pretreatment explosives in boulder blasting under the condition of overlying rock and soil with simple calculation expression and high accuracy. The specific technical scheme is as follows:

A method for determining the unit consumption of pretreatment explosives for boulder blasting under the condition of overlying rock and soil, comprising the following steps:

Obtain the unit consumption q ₁ of land blasting explosives of the same medium under the condition of no covering layer;

Obtain the water pressure depth h ₂ above the explosion zone;

Obtain the thickness h ₃ of the soft soil covering layer above the explosion zone;

Obtain the blasting step height h ₄ ;

According to the unit consumption q ₁ of land blasting explosives under the condition of no overburden layer, the unit consumption Q ₁ of basic explosives under the condition of overlying rock and soil is obtained, Q ₁ = k ₁ q ₁ , where k ₁ takes a value of 5 to 6;

According to the water pressure depth h ₂ above the explosion area, the water pressure increment Q ₂ above the explosion area is obtained, Q ₂ =0.01h ₂ ;

According to the thickness h ₃ of the overburden above the explosion zone, the overburden increment Q ₃ above the explosion zone is obtained, Q ₃ =k ₃ h ₃ , where k ₃ is 0.22;

According to the blasting step height h ₄ , the rock expansion increment Q ₄ is obtained, Q ₄ =0.03h ₄ ;

According to the formula Q=Q ₁ +Q ₂ +Q ₃ +Q ₄ , the optimal explosive unit consumption Q for boulder blasting pretreatment under the condition of overlying rock and soil is obtained, where the units of h ₂ , h ₃ and h ₄ are The unit of meter, q ₁ , Q, Q ₁ , Q ₂ , Q ₃ and Q ₄ is kilogram.

Preferably in the above technical solutions, the correction process of the revised empirical formula Q=Q ₁ +Q ₂ +Q ₃ +Q ₄ includes the following steps:

The first step: Determine the similarity law of the blasting model test under the condition of no free surface according to the material similarity, geometric parameter similarity and blasting dynamic similarity of the test;

Step 2: Determine the size of the model according to the geometric similarity ratio;

The third step: According to the similarity law of the blasting model test under the condition of no free surface in the first step and the model size in the second step, obtain the parameters of the charging device, the test block, the upper covering layer and the parameters of the test block after blasting. The average size of block degree, where the parameters of the charging device include charge radius, charge length, explosive density, detonation velocity and explosive quantity, the parameters of the test block include the strength, density and wave velocity of the test block, and the parameters of the upper covering layer include the overlying The wave impedance, density and wave velocity of the layer;

The fourth step: according to the thickness of the covering layer, at least three groups of tests are carried out under the working conditions in the third step, and the best explosive unit consumption value is selected according to the average size of the test block after blasting, and the MATLAB software is used Fit the test data to obtain the linear relationship between the thickness of the covering layer and the best explosive unit consumption of the test block blasting;

Step 5: According to the geometric similarity ratio selected in the second step, the optimal explosive unit consumption corresponding to the on-site blasting is obtained, and MATLAB software is used to fit the burial depth and the optimal explosive unit consumption data during the on-site blasting, and the buried depth is obtained. The linear relationship between the depth and the best explosive unit consumption for field blasting;

Step 6: Comparing the optimal explosive unit consumption value calculated by the Swedish empirical formula under the same working conditions with the optimal explosive unit consumption value of field blasting obtained from the formula obtained in step 5, the revised empirical formula Q can be obtained =Q ₁ +Q ₂ +Q ₃ +Q ₄ .

Preferably in the above technical scheme, the law of similarity of the blasting model test under the described condition of no free surface is:

f=(π ₁ , π ₂ , π ₃ , π ₄ , π ₅ , π ₆ , π ₇ , π ₈ )

Among them, π ₁ is the size similarity ratio between the model and the actual blasting, π ₂ is the size similarity ratio between the model and the actual blasting, π ₃ is the similarity ratio between the model and the actual blasting, and π ₄ is the test model and the geometric prototype π ₅ is the similarity ratio of charge to charge radius, π ₆ is the similarity ratio of the wave impedance of the explosive to the rock, π ₇ is the similarity ratio of the wave impedance of the rock to the covering layer, π ₈ is the wave impedance of the explosive The similarity ratio of detonation pressure to rock strength, where the values of π ₁ , π ₂ , π ₃ , π ₄ , π ₅ , π ₆ , π ₇ and π ₈ are: 0.05, 0.045, 0.15, 0.143, 0.0052, 0.43, respectively , 1.8 and 62.8.

Preferably in the above technical scheme, the geometric similarity ratio in the second step is 1:7, and the size of the model is 15cm; the charge radius in the second step is 0.68cm, and the charge length is 13.5cm; the explosive density The detonation velocity is 1000kg/m ³ , the detonation velocity is 3200m/s, the outer diameter of the detonator is 6mm, the charge of the detonator is 0.7g/shot, the length of the detonator is 7cm, and the explosive quantity is 19.7g; the density of the test block is 2200～2300kg/m ^3. The wave velocity is 3300-3500m/s, the strength is 52.0-55.0MPa; the wave impedance of the overlying layer is 4.1×10 ⁶ kg/m ² s, the density is 1600kg/m ³ , and the wave velocity is 2562m/s; the test block The average size of the lumps after blasting is 4.5cm. The best density of the field test block is 2200kg/m ³ , the best wave velocity is 3382m/s, and the best strength is 53.2MPa.

Preferably in the above technical solutions, the components of the test block are cement: sand: crushed stone with a particle size of 5-10 mm: crushed stone with a particle size of 10-20 mm: fly ash: polycarboxylic acid superplasticizer :water is 376:659:468:703:94:4.7:145.

Preferably in the above technical solutions, the working conditions in the fourth step are six groups: sand layers with no upper covering layer, upper covering layer thicknesses of 30cm, 50cm, 70cm, 100cm and 150cm and satisfying similar criteria.

Preferably in the above technical solutions, the average block size after blasting of the pilot blocks in the six groups of working conditions is 4.45-4.65 cm.

Preferably in the above technical scheme, the linear relationship between the depth of burial in the fourth step and the best explosive unit consumption of test block blasting is y=1.737x+3.386, where y is the best explosive unit consumption of test block blasting , x is the embedding depth of the test block; the linear relationship y=0.248x+3.386 between the burial depth of the boulder and the best explosive unit consumption of field blasting in the fifth step, where y is the best explosive unit consumption of field blasting, x is the embedding depth of the boulder.

The present invention has the following beneficial effects:

(1) The present invention determines the explosive list for pretreatment of boulder blasting under the condition of overlying rock and soil by first measuring various parameter values, and then calculating through the revised empirical formula Q=Q ₁ +Q ₂ +Q ₃ +Q ₄ Consumption, the measurement steps are simplified, and the calculation expression is simple to calculate. At the same time, the error between the calculated unit consumption of explosives and the unit consumption of explosives in the actual use process is small, and the accuracy is high. , to facilitate construction and improve construction efficiency.

(2) in the present invention, the correction of the empirical formula Q=Q ₁ +Q ₂ +Q ₃ +Q ₄ is obtained through six steps, and the process is simple; the correction process adopts the similar material of the model, the similar geometric parameters and the similar blasting power of the test To determine the similarity law of the blasting model test under the condition of no free surface overlying rock and soil, and to fit the relevant data through MATLAB software, the accuracy is high.

In addition to the objects, features and advantages described above, the present invention has other objects, features and advantages. Hereinafter, the present invention will be described in further detail with reference to the drawings.

Description of drawings

The accompanying drawings constituting a part of this application are used to provide further understanding of the present invention, and the schematic embodiments and descriptions of the present invention are used to explain the present invention, and do not constitute an improper limitation of the present invention. In the attached picture:

Fig. 1 is the comparison chart of the optimal explosive unit consumption calculated by the revised empirical formula of the present invention and the explosive unit consumption in the test.

Detailed ways

The embodiments of the present invention will be described in detail below with reference to the accompanying drawings, but the present invention can be implemented in various ways defined and covered by the claims.

Example 1:

A method for determining the unit consumption of pretreatment explosives for boulder blasting under the condition of overlying rock and soil, comprising the following steps:

Obtain the unit consumption q ₁ of land blasting explosives of the same medium under the condition of no covering layer;

Obtain the water pressure depth h ₂ above the explosion zone;

Obtain the thickness h ₃ of the soft soil covering layer above the explosion area, where the soft soil covering layer is preferably a covering layer with a natural void ratio greater than or equal to 1.0 such as a silt layer, a soil layer, and a sand layer;

Obtain the blasting step height h ₄ ;

According to the unit consumption q ₁ of the land blasting explosives under the condition of no overburden layer, the unit consumption Q ₁ of the basic explosives under the condition of the overlying rock and soil is obtained, Q ₁ =k ₁ q ₁ ;

According to the water pressure depth h ₂ above the explosion area, the water pressure increment Q ₂ above the explosion area is obtained, Q ₂ =0.01h ₂ ;

According to the thickness h ₃ of the overburden layer above the explosion zone, the overburden increment Q ₃ above the explosion zone is obtained, Q ₃ =k ₃ h ₃ ;

According to the blasting step height h ₄ , the rock expansion increment Q ₄ is obtained, Q ₄ =0.03h ₄ ;

According to the formula Q=Q ₁ +Q ₂ +Q ₃ +Q ₄ , the optimal explosive unit consumption Q for boulder blasting pretreatment under the condition of overlying rock and soil is obtained, where the units of h ₂ , h ₃ and h ₄ are The unit of meter, q ₁ , Q, Q ₁ , Q ₂ , Q ₃ and Q ₄ is kilogram.

The comparison between the unit consumption of the optimal explosive obtained through the above steps and the actual test data is shown in Figure 1. The two straight lines basically overlap, and the error between the two is very small, which is convenient for construction and improves construction efficiency.

The correction process of the formula Q=Q ₁ +Q ₂ +Q ₃ +Q ₄ includes the following steps:

Step 1: Determine the similarity law of the blasting model test under the condition of no free surface according to the similarity of model materials, geometric parameters and test blasting dynamics, and use the π theorem of the similarity criterion and the dimensional analysis method to determine the similarity criterion of the field blasting. The selected physical quantities Its dimensions and values are detailed in Table 1:

Table 1 Physical quantity, physical meaning and dimension in model test

serial number symbol name unit dimension value 1 Q amount of explosive kg m / 2 v explosive detonation velocity m/s LT ^-1 4000 3 ρ explosive density kg/ ^m3 ML ^-3 1200 4 R Charge radius m L 0.45

5 h Charge length m L 0.90 6 ρ _r rock density kg/ ^m3 ML ^-3 2800 7 V _r rock velocity m/s LT ^-1 4000 8 σ _r rock strength N/ ^m2 M/ ^LT2 1×106 9 L Rock size (cube) m L 1.00 10 D. Average lumpiness of rock fragmentation m L 0.30 11 h Rock depth m L / 12 _ρc Overlying layer density kg/ ^m3 ML ^-3 2600 13 v _c Overlying wave velocity m/s LT ^-1 2400

The dosage of the field test is mainly affected by various factors and expressed by the following equation:

Q=f(v, ρ, R, h, ρ _r , c _r , σ _r , L, D, H, σ _c , v _c )

In the above formula, Q is the dependent variable, and the rest are independent variables. There are three basic dimensions, and v, ρ, and R are taken as independent dimensions. According to the π theorem and the dimensional analysis method, the following dimensionless similarity criterion is obtained:

π ₁ =R/h, π ₂ =R/L, π ₃ =R/D, π ₄ =L/H, π ₅ =σ _r /ρv ² , π ₆ =ρv/ρ _r v _r , π ₇ = ρ _r v _r /ρ _c v _c , π ₈ =Q/ρR ³ .

The similarity law of the blasting model test under the condition of no free surface is: f=(π ₁ , π ₂ , π ₃ , π ₄ , π ₅ , π ₆ , π ₇ , π ₈ )

Among them, π ₁ is the size similarity ratio between the model and the actual blasting, π ₂ is the size similarity ratio between the model and the actual blasting, π ₃ is the similarity ratio between the model and the actual blasting, and π ₄ is the test model and the geometric prototype π ₅ is the similarity ratio of charge to charge radius, π ₆ is the similarity ratio of the wave impedance of the explosive to the rock, π ₇ is the similarity ratio of the wave impedance of the rock to the covering layer, π ₈ is the wave impedance of the explosive The similarity ratio of detonation pressure to rock strength, where the values of π ₁ , π ₂ , π ₃ , π ₄ , π ₅ , π ₆ , π ₇ and π ₈ are: 0.05, 0.045, 0.15, 0.143, 0.0052, 0.43 , 1.8, 62.8;

Step 2: According to the geometric similarity ratio of 1:7, determine the size of the model as 15cm;

The third step: According to the similarity law of the blasting model test under the condition of no free surface in the first step and the model size in the second step, the charge radius is 0.68cm, the charge length is 13.5cm; the explosive density is 1000kg/ m ³ , the detonation velocity is 3200m/s, the outer diameter of the detonator is 6mm, the charge of the detonator is 0.7g/shot, the length of the detonator is 7cm, and the explosive quantity is 19.7g; the density of the test block is 2200～2300kg/m ³ , the wave velocity 3300~3500m/s, strength 52.0~55.0MPa; the wave impedance of the overlying layer is 4.1×106kg/m ² s, the density is 1600kg/m ³ , and the wave velocity is 2562m/s; The average size is 4.5cm; the best density of the field test block is 2200kg/m ³ , the best wave velocity is 3382m/s, and the best strength is 53.2MPa; wherein, the composition ratio of the test block is cement:sand:grain Gravel with a diameter of 5-10mm: gravel with a particle size of 10-20mm: fly ash: polycarboxylate superplasticizer: water: 376:659:468:703:94:4.7:145;

Step 4: Carry out six groups of working condition tests according to the thickness of the covering layer, namely: the sand layer with no upper covering layer, the thickness of the upper covering layer is 30cm, 50cm, 70cm, 100cm and 150cm and meets similar criteria, The experimental data are shown in Table 2 below:

Table 2 The amount of blasting charge, the average block size after blasting and the best unit consumption of explosives

Select the best explosive unit consumption value according to the average size of the block after the test block is blasted (closest to 4.5cm), see Table 3 for details:

Table 3 Covering layer thickness, optimal explosive unit consumption and test phenomena in the test

And use MATLAB software to fit the test data of covering layer thickness and best unit consumption in Table 3, and obtain the linear relationship between covering layer thickness and best explosive unit consumption of test block blasting, y=1.737x+3.386, where y is the best explosive unit consumption for the test block blasting, and x is the burial depth of the test block;

Step 5: According to the geometric similarity ratio of 1:7, the optimal unit consumption of explosives corresponding to field blasting is obtained, as shown in Table 4 for details:

Table 4 The unit consumption of explosives for model tests and on-site blasting

MATLAB software is used to fit the data of burial depth and optimal explosive unit consumption during on-site blasting, and the linear relationship between burial depth and optimal explosive unit consumption of on-site blasting is obtained:

y=0.248x+3.386(1)

In the above formula, y is the best explosive unit consumption of on-site blasting, and x is the embedding depth of boulders;

Step 6: Compare the explosive unit consumption value calculated by the Swedish empirical formula commonly used in the above six buried depths with the optimal explosive unit consumption value obtained by formula (1), see Table 5 for details Show:

Table 5 Comparison of unit consumption of explosives between the Swedish empirical formula and the revised formula

It can be seen from Table 5 that when blasting under the condition of overlying rock and soil, the actual unit consumption of explosives under six different buried depth conditions is 3.1 to 4.9 times that calculated by the commonly used Swedish empirical formula. According to the principle of rock breaking by blasting, the actual unit consumption of explosives The main reason for the increase in consumption is that the commonly used Swedish empirical formula does not take into account the requirement of blasting fragmentation, and the second is that due to the vertical constraint of the gravity of the overlying rock and soil strata, the blasting source has no adjacent free surface. Therefore, it is necessary to revise the Swedish formula considering the requirement of shield excavation that the block size of boulder blasting should be less than 30 cm and the constraint effect of the overlying rock strata. Since the water pressure increment Q ₂ above the blast zone considering the water depth and the boulder blasting expansion increment Q ₄ considering the step height in the commonly used Swedish empirical formula have been recognized by the industry, therefore, the sub-items of Q ₂ and Q ₄ and their coefficients The value is still determined according to the commonly used Swedish empirical formula, only Q ₁ and Q ₃ need to be corrected:

Q ₁ is the unit consumption of basic explosives, Q ₁ = k ₁ q ₁ , q ₁ is the unit consumption of explosives in open-air land step blasting under the condition of no covering layer, and k ₁ is the effect of explosive detonation velocity on consideration of blasting block size requirements, water depth and covering layer thickness A composite modifier to reduce the impact. Because the average unit consumption of ordinary hard rock blasting on land is generally 0.6kg/m ³ , and the unit consumption of basic explosive Q ₁ = 3.39kg/m ³ was obtained from the test, it can be determined that the unit consumption Q ₁ of the basic explosive is 0.6kg/m 3 5 to 6 times the unit consumption of rock blasting, that is, the value of k ₁ is 5 to 6. ;

Q ₃ is the overburden increment above the explosion area, Q ₃ =k ₃ h ₃ , h ₃ is the thickness of the overlying rock and soil layer in meters, and k ₃ is a correction factor considering the influence of overburden thickness constraints. According to formula (1) in Table 5, the optimal explosive unit consumption values of the six working conditions are subtracted from the values of Q ₁ , Q ₂ and Q ₄ in each working condition to obtain the The unit consumption value of explosives, through data analysis, the linear regression relationship Q ₃ =0.22h ₃ between the overburden increment Q ₃ and the thickness of the overburden above the explosion zone can be obtained, that is, the correction coefficient k ₃ =0.22;

According to the above analysis, the Swedish empirical formula Q=Q ₁ +Q ₂ +Q ₃ +Q ₄ can be revised, where:

Q is the optimal unit consumption of explosives for boulder blasting under the overlying rock and soil conditions including the requirement that the block size is less than 30cm;

Q ₁ is the unit consumption of basic explosives under the overlying rock and soil conditions, which is 5 to 6 times the unit consumption q ₁ of general land bench blasting explosives, that is, Q ₁ = k ₁ q ₁ , where k ₁ takes a value of 5 to 6;

Q ₂ is the water pressure increment above the explosion zone, Q ₂ =0.01h ₂ , h ₂ is the water pressure depth above the explosion zone, the unit is meter;

Q ₃ is the overburden increment above the explosion area, Q ₃ =0.22h ₃ , h ₃ is the thickness of the overburden layer (silt or soil, sand, etc.) above the explosion area, in meters;

Q ₄ is the rock expansion increment, q ₄ =0.03h ₄ , h ₄ is the height of the blasting steps, in meters.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (9)

1. a method for determining unit consumption of solitary rock blasting pretreatment explosives under overlying rock and soil conditions, is characterized in that: comprise the following steps: Obtain the unit consumption q ₁ of land blasting explosives of the same medium under the condition of no covering layer; Obtain the water pressure depth h ₂ above the explosion zone; Obtain the thickness h ₃ of the soft soil covering layer above the explosion zone; Obtain the blasting step height h ₄ ; According to the unit consumption q ₁ of land blasting explosives in the same medium under the condition of no covering layer, the unit consumption Q ₁ of basic explosives under the condition of overlying rock and soil is obtained, Q ₁ = k ₁ q ₁ , where k ₁ takes a value of 5 to 6; According to the water pressure depth h ₂ above the explosion area, the water pressure increment Q ₂ above the explosion area is obtained, Q ₂ =0.01h ₂ ; According to the thickness h ₃ of the soft soil covering layer above the blast area, the cover layer increment Q ₃ above the blast area is obtained, Q ₃ =k ₃ h ₃ , where k ₃ is 0.22; According to the blasting step height h ₄ , the rock expansion increment Q ₄ is obtained, Q ₄ =0.03h ₄ ; According to the formula Q=Q ₁ +Q ₂ +Q ₃ +Q ₄ , the optimal explosive unit consumption Q for boulder blasting pretreatment under the condition of overlying rock and soil is obtained, where the units of h ₂ , h ₃ and h ₄ are The unit of meter, q ₁ , Q, Q ₁ , Q ₂ , Q ₃ and Q ₄ is kilogram. 2. The method for determining the unit consumption of pretreatment explosives for boulder blasting under the condition of overlying rock and soil according to claim 1, characterized in that: the correction of the formula Q=Q ₁ +Q ₂ +Q ₃ +Q ₄ The process consists of the following steps: The first step: Determine the similarity law of the blasting model test under the condition of no free surface according to the material similarity, geometric parameter similarity and blasting dynamic similarity of the test; Step 2: Determine the size of the model according to the geometric similarity ratio; The third step: According to the similarity law of the blasting model test under the condition of no free surface in the first step and the model size in the second step, obtain the parameters of the charging device, the test block, the upper covering layer and the parameters of the test block after blasting. The average size of block degree, where the parameters of the charging device include charge radius, charge length, explosive density, detonation velocity and explosive quantity, the parameters of the test block include the strength, density and wave velocity of the test block, and the parameters of the upper covering layer include the overlying The wave impedance, density and wave velocity of the layer; Step 4: Carry out at least three sets of tests under the premise of meeting the parameters in the third step according to the thickness of the covering layer, select the best explosive unit consumption value according to the average size of the test block after blasting, and use MATLAB software Fit the test data to obtain the linear relationship between the thickness of the covering layer and the best explosive unit consumption of the test block blasting; Step 5: According to the geometric similarity ratio selected in the second step, the optimal unit consumption of explosive corresponding to on-site blasting is obtained, and MATLAB software is used to fit the burial depth and the data of the best unit consumption of explosive during on-site blasting to obtain the isolated The linear relationship between the depth of rock burial and the best unit consumption of explosives for field blasting; Step 6: Comparing the optimal explosive unit consumption value calculated by the Swedish empirical formula under the same working conditions with the optimal explosive unit consumption value of on-site blasting obtained from the linear relationship obtained in step 5, the revised empirical formula can be obtained Q=Q ₁ +Q ₂ +Q ₃ +Q ₄ . 3. the determination method of the pretreatment explosive unit consumption of boulder blasting under the overlying rock-soil condition according to claim 2, is characterized in that: the law of similarity of the blasting model test under the described no free surface condition is: f=(π ₁ , π ₂ , π ₃ , π ₄ , π ₅ , π ₆ , π ₇ , π ₈ ) Among them, π ₁ is the size similarity ratio between the model and the actual blasting, π ₂ is the size similarity ratio between the model and the actual blasting, π ₃ is the similarity ratio between the model and the actual blasting, and π ₄ is the test model and the geometric prototype π ₅ is the similarity ratio of charge to charge radius, π ₆ is the similarity ratio of the wave impedance of the explosive to the rock, π ₇ is the similarity ratio of the wave impedance of the rock to the covering layer, π ₈ is the wave impedance of the explosive The similarity ratio of detonation pressure to rock strength, where the values of π ₁ , π ₂ , π ₃ , π ₄ , π ₅ , π ₆ , π ₇ and π ₈ are: 0.05, 0.045, 0.15, 0.143, 0.0052, 0.43, respectively , 1.8 and 62.8. 4. The method for determining the unit consumption of explosive pretreatment in boulder blasting under the condition of overlying rock and soil according to claim 2, characterized in that: in the second step, the geometric similarity ratio is 1:7, and the model is a side A cube with a length of 15cm; the charge radius in the third step is 0.68cm, and the charge length is 13.5cm; the explosive density is 1000kg/m ³ , the detonation velocity is 3200m/s, the detonator outer diameter is 6mm, and the detonator charge is 0.7 g/shot, the length of the detonator is 7cm, the amount of explosive is 19.7g; the density of the test block is 2200-2300kg/m ³ , the wave velocity is 3300-3500m/s, the strength is 52.0-55.0MPa; the wave impedance of the upper cladding layer is 4.1×10 The density of ⁶ kg/m ² s material is 1600kg/m ³ , and the wave velocity is 2562m/s; the average size of the test block after blasting is 4.5cm. 5. The method for determining unit consumption of pretreatment explosives in boulder blasting under the condition of overlying rock and soil according to claim 4, characterized in that: the density of the third step pilot block is 2200kg/m ³ , and the wave velocity is 3382m/s, the strength is 53.2MPa. 6. the method for determining the unit consumption of explosive pretreatment explosives for boulder blasting under the overlying rock-soil condition according to claim 4, is characterized in that: the component ratio of described test block is cement: sand: particle diameter is 5～ 10mm gravel: gravel with a particle size of 10-20mm: fly ash: polycarboxylate superplasticizer: water is 376:659:468:703:94:4.7:145. 7. The method for determining unit consumption of solitary rock blasting pretreatment explosives under the condition of overlying rock and soil according to claim 2, characterized in that: the test in the fourth step is six groups: the upper part has no covering layer, the upper part Sand layers with overburden thicknesses of 30 cm, 50 cm, 70 cm, 100 cm and 150 cm, respectively, satisfying similar criteria. 8. The method for determining the unit consumption of pretreatment explosives for boulder blasting under the condition of overlying rock and soil according to claim 7, characterized in that: the average block size of the test block after blasting in the test is 4.45 to 4.65 cm . 9. The method for determining the unit consumption of pretreatment explosives for boulder blasting under the condition of overlying rock and soil according to claim 8, characterized in that: the burial depth of the test block in the fourth step and the optimal explosive unit consumption of the test block blasting The linear relationship between consumption is y=1.737x+3.386, wherein y is the best explosive unit consumption of test block blasting, and x is the buried depth of test block; The linear relationship between them is y=0.248x+3.386, where y is the best explosive unit consumption of on-site blasting, and x is the embedding depth of boulders.