Method for calculating effective energy of explosive in blasting demolition

Abstract

The invention discloses a method for calculating effective energy of explosives in blasting demolition, and relates to the technical field of blasting engineering. The method is used in a blasting demolition project of a reinforced concrete (RC) structure, and comprises the following specific steps: firstly, according to known parameters, based on a Rittinger theory, determining the crushing energy of concrete by calculating the newly increased surface area of a concrete fragment after blasting; secondly, the longitudinal bars are regarded as simply supported beams, and the bending deformation energy of the longitudinal bars is calculated based on the elastic theory and the plastic ultimate bending moment; and finally, defining the sum of the crushing energy of the concrete and the bending deformation energy of the longitudinal bars as effective energy of demolition damage, and calculating the effective energy and the proportion of the effective energy in the total energy of explosive explosion. According to the method, effective energy distribution of the explosive can be accurately quantified, the amount of the explosive can be regulated and controlled, the defect that the amount of the explosive is determined by depending on an experience method and a repeated trial explosion method in the prior art is overcome, and a scientific calculation method is provided for determining the amount of the explosive.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of blasting engineering, in particular to a method for calculating effective energy of explosives in blasting demolition, which is suitable for reinforced concrete (RC) structure blasting demolition engineering, accurately quantifies energy distribution of explosives and effective energy proportion of demolition damage, and provides a new calculation method for the amount of explosives required for blasting RC columns in blasting demolition. BACKGROUND

[0002] In the reinforced concrete structure blasting demolition engineering, the energy released by explosives is used for concrete crushing, longitudinal reinforcement deformation, and flying stones, etc. Research shows that the residual bearing capacity of RC columns is mainly affected by the center blast crater length and the bending deformation of longitudinal reinforcement, and the energy such as flying and air overpressure is irrelevant. Therefore, the sum of the energy absorbed by concrete crushing and steel deformation is defined as the effective energy of demolition damage. Since the existing technology relies on empirical methods and repeated blasting to determine the amount of explosives, it is difficult to balance safety and effectiveness. By calculating the effective energy proportion, the amount of explosives can be scientifically estimated to prevent risks caused by excessive use or incomplete demolition caused by insufficient use. Therefore, a method for accurately calculating the effective energy of demolition damage and its proportion of total energy is needed to determine the amount of explosives required for blasting demolition. SUMMARY

[0003] The purpose of the present application is to overcome the shortcomings of the prior art, solve the technical problem that the determination of the amount of explosives in the existing reinforced concrete structure blasting demolition engineering lacks a scientific and accurate quantitative calculation method, which easily leads to safety risks caused by excessive use of explosives or incomplete demolition caused by insufficient use, and increases the cost of secondary processing.

[0004] Technical scheme: To solve the above technical problems, the present application provides a method for calculating effective energy of explosives in blasting demolition, which is suitable for reinforced concrete (RC) structure blasting demolition engineering. The method comprises the following steps:

[0005] First step: total energy conversion generated by explosive explosion, the calculation formula is as follows:

[0006]

[0007] In the formula: Q(g) is the maximum initiation explosive quantity of single hole; charge height d e (m); charge radius r e (m); explosive density p e (g / m 3 ); explosive explosion heat q e (kJ / g);

[0008] The total energy of explosive explosion in RC is composed of the crushing energy of concrete, the bending deformation energy of longitudinal reinforcement, and other energy. Therefore, the total energy can be calculated, and the calculation formula is as follows:

[0009] E t = E C + E LR + E o (2)

[0010] wherein: E C is the concrete breaking energy (J); E LR is the longitudinal reinforcement deformation energy (J); E o is other energy produced by the explosion of explosives (J);

[0011] Second step: calculation of concrete breaking energy

[0012] According to the Rittinger theory, the power consumption of concrete in the breaking process is the generation of new fracture surfaces in the breaking of concrete. The fractal theory is selected to calculate the size distribution of concrete fragments, and the calculation formula is as follows:

[0013]

[0014] wherein: G S is the unit surface energy of concrete (J·m -2 ); K IC is the I-type fracture toughness of concrete (MPa·mm 1 / 2 ); A is the new surface area of concrete broken fragments (m 2 ); E is the elastic modulus of concrete (MPa).

[0015] Since the broken concrete needs to be sieved into n levels, according to the concrete mass distribution law described by the fractal theory, the surface area of the concrete fragments after blasting is calculated, and the calculation formula is as follows:

[0016]

[0017] A = A t - A o (6)

[0018] wherein: A i is the surface area of concrete within a single particle size range (m 2 ); M c is the total mass of the blasted concrete fragments (kg); A t is the sum of the surface areas of concrete within all particle size ranges (m 2 ); ρ c is the density of concrete (kg·m -3 ); x i is the equivalent edge length of the concrete fragments (m), which can be determined by converting the length, width, and thickness of the concrete fragments into a cube; f(x i ) is the equivalent edge length less than or equal to x iThe percentage of total mass of concrete fragments; A o The surface area of ​​the damaged zone of the concrete before it breaks (m²) 2 The value can be determined by the product of the concrete edge failure length and the column cross-section side length.

[0019] Combining equations (4) to (6), the energy of concrete crushing is calculated, and the calculation formula is as follows:

[0020]

[0021] Step 3: Calculation of the deformation energy of the longitudinal reinforcement

[0022] Assuming each longitudinal reinforcement bar is considered a simply supported beam, q i (x) represents the force per unit length of the longitudinal reinforcement, perpendicular to the reinforcement. The formula for calculating the bending moment at the center point of the longitudinal reinforcement is as follows:

[0023]

[0024] Where: M max The bending moment at the fixed end is (kN·m); q i (x) represents the force per unit length perpendicular to the reinforcing bar (KN / m); L R denoted as , where is the exposed length of the longitudinal reinforcement (m); x is the exposed length of the reinforcing bar (m).

[0025] Based on elasticity theory, if we assume q i The force exerted at the midpoint of the longitudinal reinforcement per unit length is q. i With q i The relation for (x) is:

[0026] q i (x)=cos 4 β·q i (9)

[0027] according to Figure 1 As shown, we can conclude that:

[0028]

[0029] Based on equations (9) and (10), q i (x) can be represented as:

[0030]

[0031] Plastic ultimate bending moment M of longitudinal reinforcement s M s =ηM e η is the section influence coefficient; when the section is circular, η = 1.7. When plastic change begins at the center point, the bending moment at the center point is equal to the plastic limit bending moment of the longitudinal reinforcement, i.e., M.max = M s The stress of the center point of the longitudinal reinforcement can be calculated according to formula (12):

[0032]

[0033] In the formula: f y The yield strength (MPa) of the longitudinal reinforcement; d s The diameter (mm) of the longitudinal reinforcement.

[0034] According to the deformation of the longitudinal reinforcement, the deformation of a certain point of the exposed longitudinal reinforcement can be simplified into a trigonometric function, and the expression is:

[0035]

[0036] The energy required for the deformation of a single longitudinal reinforcement is:

[0037]

[0038] The total energy consumption of the longitudinal reinforcement bending deformation can be written as:

[0039]

[0040] Fourth step: removal of the damage effective energy and the proportion calculation

[0041] Combined with the energy consumed by the concrete block, the removal of the damage effective energy and the proportion of the explosive in the blasting demolition are respectively expressed as:

[0042] E e = E c +E lR (17)

[0043] η e = E e / E t (18)

[0044] The present application provides a kind of explosive effective energy calculation method in blasting demolition, compared with prior art, with the following significant beneficial effects:

[0045] 1. Realize the accurate quantification of explosive energy distribution, overcome the limitations of empirical method, the present application is based on Rittinger theory, elastic theory, plastic limit bending moment, respectively establishes the calculation model of concrete crushing energy and longitudinal deformation energy. Through quantitative calculation, the removal of the damage effective energy and its proportion in the total energy of explosive can be accurately obtained, effectively solve the problem that the determination of explosive quantity in the existing reinforced concrete (RC) structure blasting demolition engineering lacks scientific calculation method, and is dependent on empirical method and repeated blasting.

[0046] 2. The energy mechanism of demolition destruction is clarified, and the scientificity of blasting design is improved. The energy absorbed by concrete crushing and steel deformation is defined as "demolition destruction effective energy" in the application, and it is pointed out that this part of energy directly affects the residual bearing capacity of the RC column, while the irrelevant energy such as scattering and air overpressure is excluded. This definition is more in line with the actual destruction mechanism of blasting demolition, and provides a scientific basis for analyzing the influence of different parameters (such as longitudinal reinforcement diameter, stirrup spacing, etc.) on the blasting effect.

[0047] 3. The safety and economy of the project are considered. The proportion of effective energy calculated by the method of the application can scientifically estimate the required amount of explosive. It is suitable for reinforced concrete (RC) structure blasting demolition engineering, and has been verified by blasting tests of multiple groups of test pieces with different longitudinal reinforcement diameters, stirrup diameters and spacings. The test results show that the method can accurately reflect the energy utilization efficiency of explosive under different parameters, and provides a scientific and quantitative calculation method for determining the amount of explosive. BRIEF DESCRIPTION OF DRAWINGS

[0048] Figure 1 Simplified stress distribution of longitudinal reinforcement according to the application

[0049] Figure 2 A group of test pieces according to the application

[0050] Figure 3 A group of test pieces according to the application

[0051] Figure 4 A schematic diagram of the charging structure according to the application

[0052] Figure 5 Influence of each parameter on demolition destruction effective energy according to the application Figure 6 Flowchart of the algorithm according to the application

[0053] The application will be further described in detail below in combination with the drawings and examples. DETAILED DESCRIPTION

[0054] A blasting engineering test needs to test 8 RC columns with different parameters to explore the influence of longitudinal reinforcement diameter, stirrup diameter and spacing on demolition destruction effective energy. 2# rock emulsion explosive is used for blasting. According to the explosive effective energy calculation method in the application, the demolition destruction effective energy of each test piece and the proportion of total energy are accurately calculated, and the influence of different parameters on the demolition destruction effective energy of the blasting RC column is analyzed.

[0055] Step 1: Test piece design

[0056] In the blasting demolition project, part of the stirrup can be removed (pretreatment) to achieve the purpose of improving the damage effect and reducing the project cost. Therefore, the design of the test specimen considers two cases of removing the stirrup and the normal RC column. A total of 8 RC column specimens are designed and produced, and the specific design parameters are shown in Table 1. The 8 test specimens are divided into two groups. The first group of test specimens includes 4 RC columns to study the influence of longitudinal reinforcement diameter on the effective energy and proportion of demolition damage, and the test specimen design is shown in Figure 2 The second group of test specimens includes 4 RC columns to study the influence of stirrup diameter and stirrup spacing on the effective energy and proportion of demolition damage, and the test specimen design is shown in Figure 3 .

[0057] Table 1 Test specimen design parameters

[0058]

[0059] Second step: Known parameters of the test

[0060] The hole diameter of this test is 20 mm, the charge radius r e = 0.01 m, and the hole depth is 116 mm. The charge form is coupled charge, the explosive quantity is 9 g, the charge height is 32 mm, the detonator is set at the center of the charge height, and the minimum resistance line is 100 mm. The charge structure is shown in Figure 4 . 2# rock emulsion explosive is selected, and its main parameters are shown in Table 2.

[0061] Table 2 Explosive parameters

[0062] Materials Density (kg / m3 3 )]]> Detonation velocity (m / s) Detonation heat (kJ / g) 2# rock emulsion explosive 0.95 3500 3.69

[0063] Concrete: C50 concrete is used, the elastic modulus E = 3580 MPa, the concrete density p c = 2383 kg / m 3 , the I-type fracture toughness K IC = 0.474 MPa·m 1 / 2 , the measured yield strength of the steel bar is shown in Table 3, and the damage parameter measurement results of each test specimen after blasting are shown in Table 4.

[0064] Table 3 Yield strength of steel bar

[0065]

[0066] Table 4 Damage parameter measurement results

[0067]

[0068] In order to analyze the mass of each particle size of concrete fragments, the mass and mass proportion of the broken concrete fragments are listed in Tables 5 and 6, and the mass proportion is the percentage of the concrete fragments in the diameter range to the total mass of the concrete fragments.

[0069] Table 5 The quality and mass ratio of broken concrete pieces under the influence of longitudinal reinforcement diameter.

[0070]

[0071]

[0072] Table 6 The quality and mass ratio of broken concrete pieces under the influence of stirrup.

[0073]

[0074] Step 3: Calculate the effective energy and its proportion of RC column after blasting under different parameters

[0075] Take the L10-S0 specimen as an example, calculate the effective energy and its proportion of RC column after blasting, the known parameters of L10-S0 specimen include:

[0076] C50 concrete is used, the concrete strength grade is 58.5MPa, the elastic modulus of concrete E = 3580MPa, the density of concrete p = 2383kg / m3, the I-type fracture toughness K = 0.474MPa·m, the longitudinal reinforcement yield strength f = 458MPa, the exposed length of longitudinal reinforcement after blasting L = 521.3mm, the bending deformation of longitudinal reinforcement L = 43.1mm, the diameter of longitudinal reinforcement ds = 10mm, the number of longitudinal reinforcement n = 4, the maximum single-hole explosive charge Q(g) = 9g, and the explosive heat q = 3.69(kJ / g). c 3 IC 1 / 2 y R a e

[0077] Step 1: The total energy generated by explosive explosion is converted, and the calculation formula is as follows:

[0078] E t = Qq e = 9 × 3.69 = 33.2J (1)

[0079] In the formula, E is the total energy generated by explosive explosion, Q(g) is the maximum single-hole explosive charge, and q is the explosive heat. t e

[0080] Step 2: Calculate the concrete breaking energy E c

[0081] According to the mass of each particle size in Table 4 and formula (5), the total new area of L10-S0 specimen after blasting is A​​​​​​​​​​​t = 1.22 x 10 6 mm 2 According to the field measurement, the area of the region before the damage is A0= 0.15 x 10 6 mm 2 The new surface area A = 1.07 m 2 is calculated by formula (6), and the concrete crushing energy is calculated by the following formula:

[0082]

[0083] In the formula: E c is the concrete crushing energy; K IC is the I-type fracture toughness of concrete; E is the elastic modulus of concrete; and A is the new surface area of the concrete crushing fragments.

[0084] Third step: calculation of longitudinal reinforcement bending deformation energy

[0085] According to formula (13) and formula (15), the bending deformation energy of a single longitudinal reinforcement is E li = 138.89 J. Based on the bending deformation energy of a single longitudinal reinforcement, the total deformation energy of the longitudinal reinforcement is calculated by accumulation, and the calculation formula is as follows:

[0086]

[0087] In the formula: n is the number of longitudinal reinforcements; ds is the diameter of the longitudinal reinforcement, fy is the yield strength, and the measured bending deformation La and the exposed length L R The integral formula is used to calculate the deformation energy E li of a single longitudinal reinforcement.

[0088] Fourth step: calculation of demolition damage effective energy and proportion

[0089] Combined with the concrete crushing energy and the longitudinal reinforcement deformation energy, the demolition damage effective energy and proportion of the explosive in the blasting demolition are calculated, and the calculation formula is as follows:

[0090] E e = E c + E LR = 134.26 + 555.56 = 689.8 J

[0091]

[0092] In the formula: E e is the demolition damage effective energy; η e is the total energy proportion of demolition damage; E c is the concrete crushing energy calculated above; and E LR is the longitudinal reinforcement deformation energy calculated above.

[0093] Take the L10-S0 test piece as an example, the effective energy of explosive demolition damage in each RC column and the proportion are calculated. According to the test results and the calculation method, the calculation results of each test piece are listed in Table 7.

[0094] Table 7 Calculation results of demolition damage energy

[0095]

[0096]

[0097] According to the test and calculation results, the effective energy of explosive demolition damage and the proportion after blasting of the 8 groups of test pieces are shown in Figure 5 Based on the influence of the length of the edge damage of the concrete and the bending deformation of the steel bar on the residual bearing capacity after blasting, a calculation method of the effective energy of explosive demolition damage in blasting demolition is proposed. Through the calculation of the new method, it is shown that the effective energy of explosive demolition damage in blasting reinforced concrete column increases with the increase of the diameter of longitudinal reinforcement, the decrease of the diameter of stirrup and the increase of the spacing of stirrup.

[0098] In summary, the scientificity and accuracy of the new calculation method are verified by the test, and the effective energy of explosive demolition damage and the proportion can be calculated according to the new calculation method of the effective energy of explosive in blasting demolition. The precise quantification of the effective energy of explosive in RC column blasting demolition engineering, the regulation and control of the amount of explosive, overcome the deficiency of the existing technology which depends on the experience method and the trial blasting method to determine the amount of explosive, provide a scientific calculation basis for optimizing the blasting scheme, ensuring the safety and economy of the project.

Claims

1. A method of calculating effective energy of explosive in blasting demolition, characterized by, The method comprises the following steps: First step: the total energy conversion generated by the explosion of explosives, the calculation formula is as follows: where: Q(g) is the maximum charge weight of a single hole; charge height d e (m); charge radius r e (m); explosive density p e (g / m 3 ); explosive explosion heat q e (kJ / g); The total energy of the explosion of explosives in RC is composed of the crushing energy of concrete, the bending deformation energy of longitudinal reinforcement and other energy, so the total energy can be calculated, and the calculation formula is as follows: E t = E C + E LR + E o (2) wherein: E C is the energy of the concrete fracture (J); E LR is the energy of the longitudinal reinforcement deformation (J); E o is the other energy produced by the explosion of the explosive (J); Second step: calculation of concrete crushing energy According to Rittinger theory, the power consumption of concrete in the crushing process is the generation of new fracture surface in the destruction of concrete, the fractal theory is selected to calculate the size distribution of concrete fragments, and the calculation formula is as follows: wherein: G S is the specific surface energy of the concrete (J m -2 ) ; K IC is the mode I fracture toughness of the concrete (MPa mm 1 / 2 ) ; A is the new surface area of the broken concrete pieces (m 2 ) ; and E is the elastic modulus of the concrete (MPa). Since the broken concrete needs to be sieved into n levels, according to the concrete mass distribution law described by the fractal theory, the surface area of the concrete fragments after blasting is calculated, and the calculation formula is as follows: A = A t - A o (6) In the formula: A i is the surface area of the concrete in a single particle size range (m 2 ); M c is the total mass of the blasted concrete chunks (kg); A t is the total sum of the surface area of the concrete in all particle size ranges (m 2 ); p c is the density of the concrete (kg·m -3 ); x i is the equivalent side length of the concrete chunks (m), which can be determined by converting the concrete chunks into cubes according to the length, width, and thickness values; f(x i ) is the cumulative mass proportion of the concrete chunks with an equivalent side length less than or equal to x i ; A o is the surface area of the damage zone of the concrete before breaking (m 2 ), which can be determined by the product of the edge damage length of the concrete and the side length of the column section. Combined with formula (4)~(6), the concrete crushing energy is calculated, and the calculation formula is as follows: Third step: energy calculation of longitudinal reinforcement bending deformation Assume that each longitudinal reinforcement is regarded as a simply supported beam, q i (x) represents the force per unit length of longitudinal reinforcement, which is directed perpendicular to the longitudinal reinforcement. Step I: calculation of the center point bending moment of longitudinal reinforcement, the calculation formula is as follows: where: M max is the fixed-end bending moment (KN-m); q i (x) is the force per unit length normal to the reinforcement (KN / m); L R is the exposed length of the longitudinal reinforcement (m); x is the exposed length of the reinforcement (m). Based on the elastic theory, if assuming q i The force of the longitudinal reinforcement midpoint per unit length, then q i The relationship between q i (x) is: q i (x) = cos 4 β·q i (9) According to the figure 1, it is obtained that: Based on equation (9) and equation (10), q i (x) can be expressed as: plastic limit bending moment of longitudinal reinforcement s where M s = ηM e , η is a cross-section influence coefficient, when the cross-section is circular, η = 1.7, when the center point begins to change plastically, the bending moment of the center point is equal to the plastic limit bending moment of longitudinal reinforcement, i.e. M max = M s , the stress of the center point of longitudinal reinforcement can be calculated according to formula (12): wherein: f y is the yield strength of the longitudinal reinforcement (MPa); d s is the diameter of the longitudinal reinforcement (mm). According to the deformation of longitudinal reinforcement, the deformation of a certain point of the exposed longitudinal reinforcement can be simplified into a triangular function, and the expression is: Then the energy required for the deformation of a single longitudinal reinforcement is: Then the total energy consumption of longitudinal reinforcement bending deformation can be written as: Fourth step: calculation of demolition damage effective energy and proportion Combined with the energy consumed by the concrete fragments, the demolition damage energy of the explosives in the blasting demolition and the demolition damage energy proportion are respectively expressed as: E e = E c + E lR (17) η e = E e / E t (18) 2. The method according to claim 1, wherein, The specific steps of the screening and parameter measurement of the concrete fragments after the blasting of the RC column are as follows: ①Material taking: after the blasting of the RC column, all the concrete fragments in the blast crater and the surrounding 1.5m range are collected to ensure that the total mass proportion is greater than or equal to 92% to meet the representativeness, and to avoid the deviation caused by incomplete sampling; ②Screening: standard sieves are used to divide into n levels according to particle size (such as 0-10mm, 11-20mm…>80mm), the adjacent level particle size interval is continuous and has no overlap, and each level is screened for not less than 15 minutes, and through sufficient screening, the fragments are completely separated in the corresponding particle size level without cross-level residue; ③ Parameter determination, for each grade of broken block, randomly select not less than 30 samples, use vernier caliper (accuracy 0.02mm) measure its length, width, thickness value, according to the cube equivalent principle (equivalent side length =(long x wide x thick) ^ (1 / 3)) conversion concrete broken block equivalent side length; Using electronic scale (accuracy 0.1g) weigh each grade broken block quality, calculate the cumulative mass ratio m of the mass of the grade to the total broken block mass i ; By measuring the geometric size (such as the length of the damaged area edge, the cross-sectional edge length, etc.) of the damaged area of the RC column before blasting, the surface area A0 is obtained according to the rectangular or irregular figure area calculation formula.

3. The method according to claim 2, wherein, The number of screening levels n is not less than 9, and the mesh size of the smallest particle size level is not greater than 10mm to accurately cover the common particle size range of the concrete fragments after blasting; the equivalent side length measurement accuracy is not less than 0.02mm, and the mass weighing accuracy is not less than 0.1g, so as to ensure that the parameter measurement error is controlled within an acceptable range and the accuracy of subsequent energy calculation is ensured.

4. The method of claim 1, wherein, The specific steps of the measurement of the concrete mechanics parameters are as follows: ①Preparation of test pieces: not less than 6 groups of cubic test pieces (100mm×100mm×100mm) are prepared from the same batch of concrete as the blasting test pieces, the curing age is consistent with the blasting test pieces, the test piece preparation quality meets the standard requirements, and the representativeness is ensured; ②Compression strength test: the compression test machine is used to test the cubic test pieces, the loading rate is 0.5-0.8MPa / s, 3 groups of test pieces are tested and the average value is taken, and the concrete compression strength is calculated to check the strength grade of the test pieces; ③Elastic modulus test: axial compression test was conducted by using a servo material testing machine, and the elastic modulus of concrete was calculated according to the slope of the linear stage of the stress-strain curve by real-time acquisition, and the average value of not less than 3 groups was taken; ④I-type fracture toughness determination: a three-point bending test method was used to load the rectangular beam specimen containing a prefabricated crack, and the load-crack opening displacement curve was obtained, and the I-type fracture toughness was determined by the critical load and the geometry of the specimen; ⑤Data checking: all measured parameters should be compared with the design values, and if the deviation exceeds 10%, the corresponding parameters of concrete in the calculation formula of the breaking energy should be retested or corrected to ensure the accuracy of the energy calculation.

5. The method of claim 1, wherein, The specific steps for determining the mechanical parameters of longitudinal reinforcement are as follows: ①Material selection: longitudinal reinforcement samples are taken from RC columns that are not completely broken, the length of the sample is not less than 150mm (and not less than 10 times the diameter of the longitudinal reinforcement), and the number of samples is not less than 5, to ensure that the sample has sufficient representativeness to reflect the overall mechanical properties of the longitudinal reinforcement; ② Test: Tensile tests were conducted on the longitudinal reinforcement specimens using an electronic universal testing machine, with the loading rate controlled between 0.001 and 0.005 / s. -1 The stress-strain curve is acquired in real time, and the yield strength σ is determined based on the characteristics of the yield stage of the curve. y Three-point bending tests (span 150mm, loading rate 3mm / min) were conducted on the longitudinal reinforcement using a bending testing machine to verify the plastic properties of the longitudinal reinforcement under bending conditions and ensure that it conforms to the calculation assumptions of elastic-plastic deformation. ③Data processing: the average value of the yield strength measured by the tensile test and the plastic parameters measured by the bending test is taken as the final value of the mechanical parameters of the longitudinal reinforcement, and the test error is required to be controlled within 5%, if the deviation of a certain test data is too large (more than ±10% of the average value), the sample needs to be selected again for supplementary test.

6. The method according to claim 5, wherein, In the tensile test process, the force and displacement data need to be collected in real time, and the sampling frequency should not be less than 10Hz, in order to completely capture the stress change process of the longitudinal reinforcement from the elastic stage to the yield stage; in the bending test, the load value of the longitudinal reinforcement when reaching plastic deformation needs to be recorded and compared with the theoretically calculated plastic limit bending moment to verify the rationality of the calculation model; after the test, the damage form of the sample needs to be observed to ensure that the damage form meets the characteristics of elastic-plastic bending deformation and there is no abnormal brittle fracture.

7. The method for accurately calculating the destructive energy of explosives demolition according to claim 1, characterized in that, The specific steps for determining the parameters of explosives are as follows: ① Sampling, select no less than 3 samples from the same batch of explosives, each with a mass of no less than 100g, and use a density measurement method that matches the characteristics of the explosives to measure the density p of the explosives e , ensuring that the measurement results reflect the actual charge density; (2) Test, in the temperature of 20±2℃, humidity of 40%-60% environment, using the method in line with the explosive test standard to determine the heat of explosion q of explosive e , the test process needs to strictly control the environmental conditions to avoid the influence of temperature and humidity fluctuations on the determination results of the heat of explosion; ③ Data recording, the maximum single-hole explosive charge Q was determined by field weighing (accuracy 0.1 g); the depth (i.e. charge height d e ) and diameter of the charge hole (from which the charge radius r e ) was measured by tape or vernier caliper, with measurement accuracy of 0.001 m and 0.0001 m respectively, to ensure that the charge-related parameters accurately correspond to the actual construction state.

8. The method according to claim 7, wherein, The explosive density determination needs to be carried out at least three times in parallel, the deviation of results is not more than 2%, and the average value is taken as the final value of p e ; the explosion heat determination also needs to be carried out at least three times in parallel, and the average value is taken as the final value of q e after eliminating abnormal data; after all the explosive parameter determination is completed, the standard parameters provided by the explosive production manufacturer need to be compared, if the deviation exceeds 5%, the test equipment and operation process need to be checked and re-determined.

9. The method of claim 1, wherein, It also includes the steps of analyzing the influence of key parameters on the demolition breaking energy: ①Design multiple groups of RC column specimens, and change the parameters such as longitudinal reinforcement diameter, stirrup diameter, and stirrup spacing (for example, longitudinal reinforcement diameter is selected as 8mm, 10mm, 12mm, and 14mm, stirrup diameter is selected as 2mm, 4mm, and 6mm, and stirrup spacing is selected as 60mm and 80mm, other parameters such as concrete strength, type and amount of explosives, and charging structure are kept consistent to ensure the independence of a single variable on energy influence; ②For each group of test specimens, calculate the demolition failure energy E according to the method of claims 1-7 e And the proportion η e During the calculation process, the same parameter determination standard and formula must be strictly followed to avoid the results being incomparable due to differences in calculation methods; ③The change rule of E e under different parameters is compared and analyzed. The influence degree of each parameter on the demolition failure energy is determined by listing the calculation result data table of the demolition failure energy of each specimen, which provides quantitative basis for the optimization of explosive dosage and the adjustment of blasting parameters.

10. The method of claim 9, wherein the method comprises: The number of specimen groups is not less than 8, among which the longitudinal reinforcement diameter contains at least 8mm, 10mm, 12mm, and 14mm, the stirrup diameter contains at least 2mm, 4mm, and 6mm, and the stirrup spacing contains at least 60mm and 80mm, to fully cover the common RC column reinforcement parameter range in engineering; the basic parameters such as RC column cross-sectional size, column height, and concrete strength grade of each group of specimens need to be kept uniform to ensure the comparability between the specimens.

Images