Parameter design method of grouting curtain for structural protection under blasting vibration

Abstract

The present invention proposes a method for designing parameters of grouting curtains for structural protection under blasting vibration, which relates to the technical fields of underground engineering and blasting engineering, including S1: determining the main factors affecting the vibration velocity of the protected structure, and using the dimensional analysis Buckingham theorem to construct a vibration velocity prediction model containing undetermined coefficients; S2: establishing a finite element blasting numerical model to obtain structural vibration velocity data under different parameter combinations; S3: fitting the structural vibration velocity data using the vibration velocity prediction model to determine the undetermined coefficients in the vibration velocity prediction model; S4: establishing a relationship between structural vibration velocity and stress, and determining the grouting curtain design parameters that meet structural safety requirements based on engineering conditions. The present invention solves the difficult problems of the shock-absorbing effect of grouting curtains and the difficulty in determining grouting curtain parameters in actual engineering projects, effectively reduces the blasting vibration peak of the protected structure under blasting vibration, and provides a guarantee for the protection of underground and ground structures and the safe construction of blasting projects.

Description

Technical Field

[0001] The invention relates to the technical field of underground engineering and blasting engineering, and in particular to a grouting curtain parameter design method for protecting structures under blasting vibration. Background Art

[0002] As an efficient and economical method for geotechnical excavation, drilling and blasting is widely used in underground engineering construction. However, unlike mountain tunnel construction, urban underground projects face more complex geological conditions and environmental constraints. Cities have densely populated surface buildings, including various civil buildings, transportation facilities, and municipal infrastructure. Critical infrastructure such as water supply and drainage networks, gas pipelines, power pipeline corridors, and subway tunnels are located underground, all of which are sensitive to blasting vibrations.

[0003] Currently, blasting vibration control technologies used in engineering practice can be divided into three main categories: First, reinforcement measures are taken for the protected objects, such as structural reinforcement and protective wrapping. However, these methods are often limited by the constructability of existing structures and are costly. Second, control of blasting source parameters, including optimization of blasting parameters, delayed blasting, and controlled charge volume, can affect construction efficiency. However, excessive control of blasting parameters can affect construction efficiency. Third, vibration reduction measures are implemented along the propagation path of blasting seismic waves, mainly including digging vibration reduction trenches, installing vibration reduction belts, and deploying grouting curtains. Grouting curtains have become one of the most commonly used vibration reduction measures due to their ease of construction, strong adaptability, and minimal interference with existing structures.

[0004] However, the existing grouting curtain vibration reduction technology still has the following technical defects:

[0005] The vibration reduction effect of grouting curtains is difficult to accurately assess. Existing studies are mostly based on empirical formulas or simplified models, which fail to fully consider the coupled effects of multiple factors such as site conditions, blast source characteristics, and curtain parameters, resulting in insufficient accuracy in vibration reduction predictions.

[0006] There is a lack of systematic method to determine the design parameters of grouting curtains. Currently, the geometric dimensions (height, length, width) and position parameters of curtains in projects are mostly determined based on experience, lacking theoretical basis and quantitative design methods.

[0007] There is a lack of a clear correlation mechanism between structural safety control indicators and grouting curtain parameters. Existing designs fail to establish a quantitative relationship between the safety threshold of the protective structure and the curtain design parameters, making it difficult to achieve parameter optimization based on safety performance.

[0008] Therefore, how to establish a scientific and reasonable grouting curtain parameter design method to achieve effective protection of structures under blasting vibration is a key technical problem that needs to be solved urgently. Summary of the Invention

[0009] In view of this, the present invention proposes a grouting curtain parameter design method for structural protection under blasting vibration. By establishing a vibration velocity prediction model based on dimensional analysis, conducting numerical simulation verification, and constructing a vibration velocity-stress relationship, an accurate evaluation of the shock absorption effect of the grouting curtain is achieved, a systematic curtain parameter design method is provided, and a quantitative relationship between structural safety control indicators and curtain parameters is established, thereby providing reliable technical support and theoretical guidance for the safety protection of structures under blasting vibration.

[0010] The technical solution of the present invention is achieved as follows: The present invention provides a grouting curtain parameter design method for structural protection under blasting vibration, comprising:

[0011] S1. Determine the main factors affecting the vibration velocity of the protected structure and use the Buckingham theorem of dimensional analysis to construct a vibration velocity prediction model including undetermined coefficients;

[0012] S2. Establish a finite element blasting numerical model to obtain structural vibration velocity data under different parameter combinations;

[0013] S3. Fit the structural vibration velocity data using the vibration velocity prediction model to determine the undetermined coefficients in the vibration velocity prediction model;

[0014] S4. Establish a relationship between structural vibration velocity and stress, determine a safety stress threshold based on design specifications, determine a structural vibration velocity safety threshold through the relationship, substitute the structural vibration velocity safety threshold into the vibration velocity prediction model of step S3, and determine the grouting curtain design parameters that meet the structural safety requirements in combination with engineering conditions.

[0015] On the basis of the above technical solution, preferably, the grouting curtain is buried between the protective structure and the blasting source, that is, on the propagation path of the blasting stress wave, to interfere with the propagation of the blasting stress wave.

[0016] Based on the above technical solution, preferably, the main factors affecting the vibration velocity of the protection structure include:

[0017] Site parameters, including rock and soil density, rock and soil longitudinal wave velocity, rock and soil shear wave velocity, soil moisture content, and the distance between the protective structure and the blast source;

[0018] Explosive source parameters, including explosive quantity, charge diameter, blasthole diameter, explosive detonation velocity, and explosive density;

[0019] Grouting curtain parameters include grouting curtain height, grouting curtain length, grouting curtain width and the horizontal distance between the grouting curtain and the protected structure.

[0020] Based on the above technical solution, preferably, the specific steps of using the dimensional analysis Buckingham theorem to construct a vibration velocity prediction model including undetermined coefficients in step S1 include:

[0021] Three factors were selected from the main factors as dimensionally independent factors, and the remaining factors were selected as dimensionally dependent factors. Among them, any dimensionally independent factor could not be calculated from the other two dimensionally independent factors using basic data.

[0022] Convert dimensionally independent factors into dimensionless numbers through the π theorem;

[0023] According to the dimensional homogeneity theorem and combined with dimensionless numbers, a vibration velocity prediction model including undetermined coefficients is constructed.

[0024] Based on the above technical solution, preferably, the dimensionally independent factors are the amount of explosives, the distance between the protective structure and the blast source, and the longitudinal wave velocity of the rock and soil. The mathematical expression of the vibration velocity prediction model including the undetermined coefficients is as follows:

[0025]

[0026] Where V P is the vibration velocity of the protected structure; η is the damping efficiency; K, α1, α2, α3, α4, and α5 are unknown coefficients, where: c is the longitudinal wave velocity of the rock and soil mass, ρ is the density of the rock and soil mass; R1 is the distance between the protective structure and the explosion source; R2 is the horizontal distance between the grouting curtain and the protective structure; H is the height of the grouting curtain; L is the length of the grouting curtain; W is the width of the grouting curtain; Q is the amount of explosives.

[0027] Based on the above technical solution, preferably, step S2 includes:

[0028] S21. Use ANSYS / LS-DYNA software to build a three-dimensional finite element model. The model size is set according to the actual range of the explosive and the size of the blasthole.

[0029] S22. Use Lagrangian grid to divide the model, and perform grid encryption on the protection structure and its surrounding areas;

[0030] S23. Setting boundary conditions, including: using non-reflecting boundary conditions around the model and at the bottom, and using free boundary conditions at the top;

[0031] S24. Use the surface-surface contact algorithm to describe the soil-structure interaction and set the corresponding friction coefficient;

[0032] S25. Select the material constitutive model, where the soil adopts the Drucker-Prager constitutive model and the grouting curtain adopts the CONCRETE_DAMAGE_REL3 material model, and input the corresponding physical and mechanical parameters.

[0033] S26. Set the operating conditions for different parameter combinations using one of the following two methods: single factor impact analysis method, where only one major factor is changed at a time; or multi-factor orthogonal analysis method, where multiple major factors are changed simultaneously;

[0034] S27. Perform simulation calculations in a three-dimensional finite element model according to the working conditions of each parameter combination, and verify the reliability of the calculation results to obtain numerical simulation results under the working conditions of different parameter combinations;

[0035] S28. Based on the numerical simulation results under the working conditions of different parameter combinations, the structural vibration velocity data under the working conditions of different parameter combinations are statistically obtained.

[0036] Based on the above technical solution, preferably, in step S27, verifying the reliability of the calculation result includes:

[0037] The soil pressure, acceleration or vibration velocity results of the same point in the numerical simulation and the indoor model test are read through the post-processing software lsprepost. If the waveforms of the two are close, the peak values ​​are not much different, and the errors of each point are within 15%, the numerical simulation results are judged to be reliable.

[0038] Based on the above technical solution, preferably, step S4 includes:

[0039] S41. According to wave theory, the functional relationship between structural vibration velocity and stress is derived as follows:

[0040] σ=f(V p )

[0041] Where, σ is the effective stress of the protection structure; V p To protect the structural vibration velocity;

[0042] S42. Determine the safety stress threshold based on the design specifications:

[0043] [σ]=k·σ0

[0044] Where [σ] is the safety stress threshold, k is the safety factor, and σ0 is the maximum allowable stress specified in the design code;

[0045] S43. The structural vibration speed safety threshold is obtained by inversely deducing the functional relationship between structural vibration speed and stress:

[0046] [V p ]=f -1 ([σ])

[0047] In the formula, [V p ] is the structural vibration speed safety threshold, f -1 It is the inverse function of the relationship between structural vibration velocity and stress;

[0048] S44, the structural vibration speed safety threshold [V p ]Substitute the vibration velocity prediction model of step S3 and determine the grouting curtain design parameters that meet the structural safety requirements in combination with the engineering conditions.

[0049] On the basis of the above technical solution, preferably, the grouting curtain is composed of cement mortar, rubber powder, iron powder and river sand.

[0050] On the basis of the above technical solution, preferably, the protection structure includes:

[0051] Ground structures, including buildings, overhead and high-voltage towers;

[0052] Underground structures include underground pipelines, underground box culverts and underground tunnels.

[0053] The present invention has the following advantages and beneficial effects compared to the prior art:

[0054] (1) The present invention systematically solves the technical problems of difficulty in determining the vibration reduction effect and parameters of grouting curtains in actual engineering projects through dimensional analysis, numerical simulation, model verification, and parameter optimization. It provides reliable technical support for blasting vibration protection of underground and ground structures and has important engineering application value.

[0055] (2) The present invention adopts the Buckingham theorem of dimensional analysis to construct a vibration velocity attenuation prediction model, comprehensively considering multiple influencing factors such as explosive quantity, blast source distance, and grouting curtain geometric parameters, and establishes a quantitative relationship between the various parameters, thereby overcoming the defect of insufficient precision of traditional empirical formulas and improving the accuracy of vibration prediction;

[0056] (3) The present invention establishes a numerical simulation method based on ANSYS / LS-DYNA. By comparing the model reliability with the results of indoor model tests, the author realizes the efficient prediction of the structural vibration response under different working conditions, avoids a large number of physical tests, and significantly reduces the research cost.

[0057] (4) The present invention establishes a functional relationship between structural vibration velocity and stress, and combines it with the safety control indicators in the design specifications to achieve a scientific determination of the vibration velocity safety threshold, providing a theoretical basis for the optimal design of grouting curtain parameters and ensuring the reliability of the protection scheme;

[0058] (5) The parameter design method proposed in the present invention has strong practicality and versatility. It can flexibly select the geometric parameters of the grouting curtain according to the actual conditions of the project, meet the vibration reduction requirements in different engineering scenarios, and has good engineering adaptability. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0060] Figure 1 is a flow chart of a method according to an embodiment of the present invention;

[0061] Figure 2 A numerical model diagram of an embodiment of the present invention;

[0062] Figure 3 A comparison diagram of acceleration time history curves of numerical simulation and indoor model experiment of an embodiment of the present invention;

[0063] Figure 4 Schematic diagram of structural vibration velocity and stress fitting in an embodiment of the present invention. DETAILED DESCRIPTION

[0064] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0065] like Figure 1 As shown, the present invention provides a grouting curtain parameter design method for structural protection under blasting vibration, comprising:

[0066] S1. Determine the main factors affecting the vibration velocity of the protected structure and use the Buckingham theorem of dimensional analysis to construct a vibration velocity prediction model including undetermined coefficients;

[0067] S2. Establish a finite element blasting numerical model to obtain structural vibration velocity data under different parameter combinations;

[0068] S3. Fit the structural vibration velocity data using the vibration velocity prediction model to determine the undetermined coefficients in the vibration velocity prediction model;

[0069] S4. Establish a relationship between structural vibration velocity and stress, determine a safety stress threshold based on design specifications, determine a structural vibration velocity safety threshold through the relationship, substitute the structural vibration velocity safety threshold into the vibration velocity prediction model of step S3, and determine the grouting curtain design parameters that meet the structural safety requirements in combination with engineering conditions.

[0070] Specifically, in one embodiment of the present invention, protective structures can be divided into above-ground structures and underground structures based on their location. Above-ground structures primarily include buildings, elevated structures, and high-voltage towers, while underground structures primarily include underground pipelines, underground box culverts, and underground tunnels. Grouting curtains are primarily composed of cement mortar, rubber powder, iron powder, and river sand in a specific ratio, and have a certain energy absorption and shock absorption effect.

[0071] Specifically, in one embodiment of the present invention, the main factors affecting the vibration velocity of the structure under the protection of the grouting curtain mainly include three parts: site parameters, blasting source parameters and grouting curtain parameters. Among them, the site factors mainly include but are not limited to the density of the rock and soil mass, the longitudinal wave velocity of the rock and soil mass, the transverse wave velocity of the rock and soil mass, the moisture content of the soil mass, the distance between the protection structure and the blasting source, etc. The blasting source parameters mainly include but are not limited to the amount of explosives, the diameter of the charge, the diameter of the blasthole, the detonation velocity of the explosives, the density of the explosives, etc.

[0072] In this embodiment, the grouting curtain is mainly buried between the protective structure and the explosion source, that is, on the propagation path of the blasting stress wave, to interfere with the propagation of the blasting stress wave. Therefore, the grouting curtain parameters mainly include but are not limited to the grouting curtain height, grouting curtain length, grouting curtain width, and the horizontal distance between the grouting curtain and the pipeline.

[0073] Specifically, in one embodiment of the present invention, the specific steps of using the dimensional analysis Buckingham theorem in step S1 to construct a vibration velocity prediction model including undetermined coefficients include:

[0074] Three factors were selected from the main factors as dimensionally independent factors, and the remaining factors were selected as dimensionally dependent factors. Among them, any dimensionally independent factor could not be calculated from the other two dimensionally independent factors using basic data.

[0075] Convert dimensionally independent factors into dimensionless numbers through the π theorem;

[0076] According to the dimensional homogeneity theorem and combined with dimensionless numbers, a vibration velocity prediction model including undetermined coefficients is constructed.

[0077] The dimensionally independent factors are the amount of explosives, the distance between the protective structure and the blast source, and the longitudinal wave velocity of the rock and soil. The mathematical expression of the vibration velocity prediction model including the undetermined coefficients is as follows:

[0078]

[0079] Where V P is the vibration velocity of the protected structure; η is the damping efficiency; K, α1, α2, α3, α4, and α5 are unknown coefficients, where: c is the longitudinal wave velocity of the rock and soil, that is, the propagation velocity of the longitudinal wave in the medium, ρ is the density of the rock and soil; R1 is the distance between the protective structure and the explosion source; R2 is the horizontal distance between the grouting curtain and the protective structure; H is the height of the grouting curtain; L is the length of the grouting curtain; W is the width of the grouting curtain; Q is the amount of explosives.

[0080] In a specific example, the protection structure is a pipeline:

[0081] The peak vibration velocity of the pipeline under the influence of blasting vibration is affected by many factors. In this embodiment, the physical quantities shown in Table 1 are mainly selected for analysis.

[0082] Table 1 Influencing factors and dimensions

[0083] Equation parameters unit dimension <![CDATA[Peak particle velocity V of the pipeline P > <![CDATA[cm·s -1 ]]> <![CDATA[LT -1 ]]> Explosive source charge Q kg M <![CDATA[Distance R1 from the explosion source]]> m L <![CDATA[Horizontal distance R2 between grouting curtain and pipeline]]> m L Grouting curtain height H cm L Grouting curtain length L cm L Grouting curtain width W cm L Geotechnical pipe density ρ <![CDATA[g·cm -3 ]]> <![CDATA[ML -3 ]]> The propagation speed of longitudinal waves in the medium is c <![CDATA[m·s -1 ]]> <![CDATA[LT -1 ]]>

[0084] Assume that the vibration velocity of the pipeline particle V P According to the following physical expression (1):

[0085] V p ·η=F(Q,R1,R2,H,L,W,ρ,c) (1)

[0086] The physical meaning and dimension of each parameter in the formula are shown in Table 1.

[0087] According to the dimensional homogeneity theorem, Q, R1, and c are selected as dimensionally independent quantities, and other parameters are dimensionally dependent quantities. The dimensionless number can be obtained as shown in the following formula (2):

[0088]

[0089] Since the product and power of different dimensionless numbers are still dimensionless numbers, based on the above dimensionless numbers, a new dimensionless number can be constructed as follows (3):

[0090]

[0091] According to the π theorem, we can assume that the dimensionless numbers mentioned above satisfy the following relationship (4):

[0092] π=F(π1,π2,π3,π4,π6) (4)

[0093] Substituting the meaning of each π value into formula (4), we get formula (5):

[0094]

[0095] Since V PThere is a positive correlation with the explosive quantity Q and the protection distance R2, and a negative correlation with the grouting curtain height H, length L, width W, and blast source distance R1. Therefore, it can be assumed that the above parameters satisfy the following formula (6):

[0096]

[0097] For a certain site, c and ρ in the above formula are fixed, so the above formula can be rewritten as formula (7):

[0098]

[0099] So far, Equation (7) is the constructed vibration velocity prediction model including the undetermined coefficients, where K, α1, α2, α3, α4, and α5 are all undetermined coefficients, and

[0100] Specifically, in one embodiment of the present invention, step S2 includes:

[0101] S21. Use ANSYS / LS-DYNA software to build a three-dimensional finite element model. The model size is set according to the actual range of the explosive and the size of the blasthole.

[0102] S22. Use Lagrangian grid to divide the model, and perform grid encryption on the protection structure and its surrounding areas;

[0103] S23. Setting boundary conditions, including: using non-reflecting boundary conditions around the model and at the bottom, and using free boundary conditions at the top;

[0104] S24. Use the surface-surface contact algorithm to describe the soil-structure interaction and set the corresponding friction coefficient;

[0105] S25. Select the material constitutive model, where the soil adopts the Drucker-Prager constitutive model and the grouting curtain adopts the CONCRETE_DAMAGE_REL3 material model, and input the corresponding physical and mechanical parameters.

[0106] S26. Set the operating conditions for different parameter combinations using one of the following two methods: single factor impact analysis method, where only one major factor is changed at a time; or multi-factor orthogonal analysis method, where multiple major factors are changed simultaneously;

[0107] S27. Perform simulation calculations in a three-dimensional finite element model according to the working conditions of each parameter combination, and verify the reliability of the calculation results to obtain numerical simulation results under the working conditions of different parameter combinations;

[0108] S28. Based on the numerical simulation results under the working conditions of different parameter combinations, the structural vibration velocity data under the working conditions of different parameter combinations are statistically obtained.

[0109] In one embodiment of the present invention, since blasting vibration involves complex dynamic processes, relying solely on numerical simulations is difficult to guarantee the reliability of the calculated results. Extensive field testing also presents challenges such as high costs and long lead times. Therefore, a method combining indoor model testing with numerical simulations can ensure the accuracy of simulation results while controlling research costs. In practice, an indoor model test is first conducted using a 2m × 0.5m × 0.5m test chamber. A buried pipeline (0.5m in length, 9cm in outer diameter, 0.2cm in wall thickness) is laid within it, and a blasthole (1.2cm in diameter, 0.275m in depth) is set up. A blast test is then conducted. Simultaneously, a three-dimensional finite element model with identical dimensions and parameters is constructed using ANSYS / LS-DYNA software. The post-processing software lsprepost is used to retrieve the soil pressure, acceleration, and vibration velocity data at the same point in the numerical simulation and indoor model test. When the waveforms of the two waveforms are relatively close and the peak error is within 15%, the numerical simulation results are considered reliable and can be used for subsequent parameter analysis and optimization design. This method ensures the scientific nature of the research results while improving research efficiency.

[0110] In this embodiment, specifically, the model building method is:

[0111] The blasting conditions and rock mass physical and mechanical parameters of the model are consistent with the indoor model test plan. The model width should be no less than 30 times the blasthole diameter, and the model depth should be greater than or equal to 1 times the blasthole depth. The specific dimensions should be appropriately adjusted in combination with the actual range of action of the explosives. According to the indoor model test design plan, the overall size of the numerical model is determined to be 2×0.5×0.5m, see Figure 2 . The fill thickness is 0.5m, the buried pipeline is 0.5m long, the outer diameter is 9cm, the wall thickness is 0.2cm, the blasthole diameter is 1.2cm, the charge length is 5cm, the hole depth is 0.275m, and the cm-g-μs unit system is adopted. The pipeline, blasting mud, and soil layer in the numerical model are divided by Lagrangian grid, and the pipeline and the soil layer in contact with the pipeline are encrypted. The overall grid size of the model is set to vary from 1 to 2cm, and the grid of the pipeline and its surroundings varies from 0.5 to 1cm. The grid of explosives and mud blocking varies from 0.5 to 2cm.

[0112] Non-reflecting boundary conditions were set around the edges and bottom of the model, while a free boundary condition was set at the top. Surface-to-surface contact was used to describe the interaction between the pipe and the soil. This method is commonly used to describe objects of any shape with a large contact area and is very effective when dealing with large amounts of relative sliding between objects. Furthermore, the automatic contact algorithm can calculate the contact surface orientation of the shell elements. The contact between the pipe and the soil was set to automatic surface-to-surface contact, and the static friction coefficient between the pipe and the soil was set to 0.12.

[0113] The material model for silty clay is *MAT_DRUCKER_PRAGER model, with a density of 1.92 g / cm 3 , elastic modulus is 0.039 GPa, tensile strength is 0.028 MPa, Poisson's ratio is 0.35, cohesion is 0.025 MPa, and internal friction angle is 15°. The buried pipeline adopts *MAT_PLASTIC_KINEMATIC material model with a density of 1.34 g / cm 3 , elastic modulus is 2.92 GPa, tensile strength is 48 MPa, and Poisson's ratio is 0.38. Due to its strength and yield characteristics, the grouting curtain material can adopt the *MAT_CONCRETE_DAMAGE_REL3 material model with a density of 1.18 g / cm 3 , the elastic modulus is 0.042 GPa, the compressive strength is 4.32 MPa, the Poisson's ratio is 0.26, the cohesion is 1.07 kPa, the internal friction angle is 52.3°, and *EOS_TABULATED_COMPATION is used to describe the stress-strain behavior.

[0114] Before model simulation, parameter combinations are set based on the parameters of the main factors. They can be set according to the single-factor impact analysis method or the multi-factor orthogonal analysis method. The single-factor impact analysis method only changes one parameter at a time, and the other parameters remain unchanged; the multi-factor orthogonal analysis method changes multiple parameters at the same time, and the parameter combination is determined through orthogonal experimental design.

[0115] According to the set parameter combination, one parameter combination is a working condition. In the finite element software, the model is set according to the current parameter combination, and then the blasting test is simulated to calculate the numerical simulation results under different working conditions. The numerical simulation results include soil pressure data, acceleration data, and vibration velocity data.

[0116] The reliability verification of the model results is as follows: the soil pressure, acceleration or vibration velocity results of the same point of the numerical simulation and the indoor model test are read through the post-processing software lsprepost. If the waveforms of the two are close, see Figure 3 , and the peak values ​​are not much different, and the errors of each point are within 15%. It can be determined that the results of numerical simulation are consistent with reality and are reliable.

[0117] Record the structural vibration velocity data under different working conditions, count the simulation results under each parameter combination, and establish a data table to record the structural vibration velocity data results corresponding to each group of parameters.

[0118] Specifically, in one embodiment of the present invention, the core of step S3 is to use the vibration velocity prediction model derived by dimensional analysis in S1 to fit the structural vibration velocity numerical simulation results under different parameter combinations obtained in S2, so as to determine the undetermined coefficients in the prediction model. This step matches the theoretical model with the numerical simulation results through the mathematical regression method to establish a reliable prediction model. This method ensures that the model has a theoretical basis and has good engineering applicability. The reliability of the fitting result is measured by the correlation index R 2 To evaluate, ask R 2 Not less than 0.85 to ensure that the fitting results have good reliability and rationality.

[0119] In this embodiment, the structural vibration velocity data for the various parameter combinations in step S2 are collected and organized into dimensionless parameter form within the prediction model. A data table is created to record the vibration velocity results for each parameter combination. The recorded data is uniformly preprocessed, and the dimensionless parameter values ​​are calculated.

[0120] Substitute the dimensionless parameter values ​​into the mathematical expression of the vibration velocity prediction model of formula (7), perform logarithmic processing on the model, transform it into a linear equation, use the least squares method to perform multivariate linear regression, solve the unknown coefficients α1, α2, α3, α4, α5, and calculate the coefficient K value. Calculate the determination coefficient R 2 , verify R 2 Is it ≥0.85? If it does not meet the requirements, the data needs to be adjusted or refitted.

[0121] After the fitting is completed, the final values ​​of all undetermined coefficients are recorded to give a complete prediction model expression.

[0122] In this embodiment, after fitting the specific structural vibration velocity data, the pipeline peak vibration velocity prediction formula is obtained, which takes into account the influence of the grouting curtain parameters, namely, height, length, thickness, relative distance between the explosion source and the pipeline, explosive charge of the explosion source, and horizontal distance between the grouting curtain and the pipeline, as shown in formula (8):

[0123]

[0124] That is, in this embodiment, according to the specific data table, the fitting results are α1=0.179, α2=-0.215, α3=-0.017, α4=-0.561, α5=1.104, and then according to the formula The calculated K value is 9.65.

[0125] Specifically, in one embodiment of the present invention, step S4 includes:

[0126] S41. According to wave theory, the functional relationship between structural vibration velocity and stress is derived as follows:

[0127] σ=f(V p )

[0128] Where, σ is the effective stress of the protection structure; V p To protect the structural vibration velocity;

[0129] S42. Determine the safety stress threshold based on the design specifications:

[0130] [σ]=k·σ0

[0131] Where [σ] is the safety stress threshold, k is the safety factor, and σ0 is the maximum allowable stress specified in the design code;

[0132] S43. The structural vibration speed safety threshold is obtained by inversely deducing the functional relationship between structural vibration speed and stress:

[0133] [V p ]=f -1 ([σ])

[0134] In the formula, [V p ] is the structural vibration speed safety threshold, f -1 It is the inverse function of the relationship between structural vibration velocity and stress;

[0135] S44, the structural vibration speed safety threshold [V p ]Substitute the vibration velocity prediction model of step S3 and determine the grouting curtain design parameters that meet the structural safety requirements in combination with the engineering conditions.

[0136] Among them, the design specifications are mainly national standards or industry standards and other documents that have practical engineering guidance and industry recognition. The safety control indicators are mainly the vibration velocity of the protection structure, or other indicators that have a functional relationship with the vibration velocity and can be converted into each other, such as frequency, stress, etc.

[0137] Specifically, step S4 is to establish a correlation between the structural safety control requirements and the grouting curtain parameter design. Under the action of blasting vibration, the safety performance of the structure is usually judged based on the strain or stress magnitude, rather than directly using the vibration velocity. According to wave theory, there is a definite functional relationship between the vibration velocity and stress of the structure. By establishing this relationship, the stress safety control index in the design specification can be converted into a vibration velocity safety threshold, and then combined with the vibration velocity prediction model established in step S3, the grouting curtain design parameters that meet the safety requirements are determined. This method not only ensures the theoretical basis of the design, but also ensures the practicality of the project.

[0138] Specifically, the calculation ideas for grouting curtain design parameters can be described as follows:

[0139] a. Complete step S3 to obtain a vibration velocity prediction model for the protected structure that takes into account the shock absorption performance of the grouting curtain;

[0140] b. If the safety control indicator is a non-vibration velocity indicator P1, collect the vibration velocity and P1 data of the protection structure under different working conditions, and use functional fitting to obtain the relationship between the vibration velocity and P1 of the protection structure. At the same time, use the indicator safety control value of the protection structure under normal operation provided by the design specification, combined with the relationship between the vibration velocity and P1 of the protection structure to obtain the maximum allowable safe vibration velocity. If the safety control indicator is vibration velocity, skip this step.

[0141] c. Based on the engineering conditions, any two of the three main parameters of the grouting curtain (length, width, and height) are assumed and substituted into the vibration velocity prediction model of the protective structure together with the data of other influencing factors such as the amount of explosives, rock and soil density, and the horizontal distance between the grouting curtain and the pipeline to obtain the value of the third parameter of the grouting curtain.

[0142] In a specific example, taking the protected structure as a pipeline as an example, the specific implementation process of step S4 is as follows:

[0143] In the process of monitoring buried pipelines, the vibration velocity can only directly reflect the dynamic response characteristics of the pipeline. Under the influence of blasting seismic waves, the safety performance of the pipeline and the failure mode of the pipeline material are mostly judged based on the strain or stress of the pipeline. According to wave theory, it can be inferred that there should also be a mathematical function relationship between the vibration velocity and stress of the pipeline. Therefore, the data of the two obtained from various numerical model results under complex working conditions are fitted. The fitting results are shown in formulas (9) and Figure 4 .

[0144] σ=f(V p )=0.065V P -0.042 (9)

[0145] Where: σ is the peak effective stress of the pipeline, MPa; V P is the peak combined vibration velocity of the pipeline, cm·s -1 .

[0146] The Technical Specifications for Buried High-Strength Polyvinyl Chloride Water Supply Pipeline Engineering provides a calculation formula for the maximum allowable stress of the pipe body during normal operation:

[0147] MOP=PN·f t (10)

[0148] Where: MOP is the maximum allowable stress for safe operation, MPa; PN is the nominal pressure, MPa; f tWhen the life span of the pipeline is required to be 50 years, the reduction coefficient of temperature to pressure is generally calculated as 0.8 at 32°C. The maximum allowable stress calculation formula for safe operation of PVC pipes in normal operation given in the "Technical Specifications for Buried High-Strength Polyvinyl Chloride Water Supply Pipeline Engineering" is used to calculate the maximum allowable stress for safe operation of the pipeline to be 1.76MPa. In addition, considering that the pipeline may have aging problems in actual projects, its actual maximum safe allowable working stress may be slightly reduced, so the pipeline stress safety factor is taken as 0.85, that is, the actual safe operation safety stress threshold [σ] = k·σ0 = 0.85MOP = 1.496MPa. Combined with the relationship between the stress and vibration velocity of the pipeline under the influence of blasting vibration in the above formula (9), the pipeline vibration velocity threshold [V P ]=f -1 ([σ])=([σ]+0.042) / 0.065=23.66cm·s -1 .

[0149] The pipeline vibration velocity threshold [V P ]Substituting into formula (8) we can get:

[0150]

[0151] By substituting different explosive charge and distance values ​​for different projects, we can determine the relationship between the grouting curtain parameters and the horizontal distance between the grouting curtain and the pipeline. Based on the site environment and protection requirements, we can then select appropriate parameters to design the grouting curtain scheme. In this example, with a damping efficiency η = 0.85, explosive charge Q = 20 kg, and a relative distance R1 from the pipeline = 15 m, we substitute these values ​​into Equation (11) to produce the grouting curtain scheme design shown in Table 2.

[0152] Table 2 Grouting curtain design example

[0153] Protection distance / m Grouting curtain length / m Grouting curtain height / m Grouting curtain width / m 1 1 1 0.180 1.5 1 1 0.206 2 1 1 0.225 2.5 1 1 0.242 3 1 1 0.263 3.5 1 1 0.285 4 1 1 0.304

[0154] In summary, the present invention addresses the engineering challenge of protecting structures from blasting vibration by proposing a scientific grouting curtain parameter design method. The overall approach is to achieve structural protection by placing grouting curtains along the propagation path of blasting stress waves, combining theoretical analysis, numerical simulation, and engineering practice. Specifically, a vibration velocity prediction model is constructed using dimensional analysis and Buckingham's theorem. Numerical simulations are performed using ANSYS / LS-DYNA software, and a vibration velocity-stress conversion relationship is established in conjunction with design specifications to ultimately determine grouting curtain design parameters that meet safety requirements. The core principle of this invention is based on wave theory, mitigating the impact of blasting vibration on structures through the energy absorption and shock absorption of the grouting curtain material (a combination of cement mortar, rubber powder, iron powder, and river sand). This method is applicable not only to the protection of above-ground structures (such as buildings, elevated structures, high-voltage towers, etc.) and underground structures (such as underground pipelines, underground box culverts, and underground tunnels), but also ensures the reliability of the design results through rigorous theoretical derivation and numerical verification (with an error control within 15%). The present invention successfully solves the technical difficulties in determining the shock absorption effect and parameters of grouting curtains in actual projects, provides a scientific design method and reliable technical support for structural safety protection in blasting projects, and has important engineering application value.

[0155] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A grouting curtain parameter design method for structural protection under blasting vibration, characterized in that: include: S1. Determine the main factors affecting the vibration velocity of the protected structure and use the Buckingham theorem of dimensional analysis to construct a vibration velocity prediction model including undetermined coefficients; S2. Establish a finite element blasting numerical model to obtain structural vibration velocity data under different parameter combinations; S3. Fit the structural vibration velocity data using the vibration velocity prediction model to determine the undetermined coefficients in the vibration velocity prediction model; S4. Establish a relationship between structural vibration velocity and stress, determine a safety stress threshold based on design specifications, determine a structural vibration velocity safety threshold through the relationship, substitute the structural vibration velocity safety threshold into the vibration velocity prediction model of step S3, and determine grouting curtain design parameters that meet structural safety requirements based on engineering conditions; The specific steps of constructing a vibration velocity prediction model including undetermined coefficients using the dimensional analysis Buckingham theorem in step S1 include: Three factors were selected from the main factors as dimensionally independent factors, and the remaining factors were selected as dimensionally dependent factors. Among them, any dimensionally independent factor could not be calculated from the other two dimensionally independent factors using basic data. Convert dimensionally independent factors into dimensionless numbers through the π theorem; According to the dimensional homogeneity theorem and combined with dimensionless numbers, a vibration velocity prediction model including undetermined coefficients is constructed; The dimensionally independent factors are the amount of explosives, the distance between the protective structure and the blast source, and the longitudinal wave velocity of the rock and soil. The mathematical expression of the vibration velocity prediction model including the undetermined coefficients is as follows: , where To protect the structural vibration velocity; For shock absorption efficiency; 、 、 、 、 、 is the unknown coefficient, among which, , is the longitudinal wave velocity of rock and soil, is the density of rock and soil; The distance between the protective structure and the explosion source; is the horizontal distance between the grouting curtain and the protected structure; is the height of the grouting curtain; is the length of the grouting curtain; is the width of the grouting curtain; is the amount of explosives; Step S4 includes: S41. According to wave theory, the functional relationship between structural vibration velocity and stress is derived as follows: , where To protect the effective stress of the structure; To protect the structural vibration velocity; S42. Determine the safety stress threshold based on the design specifications: , where is the safety stress threshold, is the safety factor, The maximum allowable stress specified in the design code; S43. The structural vibration speed safety threshold is obtained by inversely deducing the functional relationship between structural vibration speed and stress: , where is the structural vibration speed safety threshold, It is the inverse function of the relationship between structural vibration velocity and stress; S44, the structural vibration speed safety threshold Substitute the vibration velocity prediction model in step S3 and determine the grouting curtain design parameters that meet the structural safety requirements based on the engineering conditions.

2. The grouting curtain parameter design method for structural protection under blasting vibration according to claim 1, characterized in that: The grouting curtain is buried between the protective structure and the blasting source, that is, on the propagation path of the blasting stress wave, to interfere with the propagation of the blasting stress wave.

3. The grouting curtain parameter design method for structural protection under blasting vibration according to claim 2, characterized in that: The main factors affecting the vibration velocity of the protective structure include: Site parameters, including rock and soil density, rock and soil longitudinal wave velocity, rock and soil shear wave velocity, soil moisture content, and the distance between the protective structure and the blast source; Explosive source parameters, including explosive quantity, charge diameter, blasthole diameter, explosive detonation velocity, and explosive density; Grouting curtain parameters include grouting curtain height, grouting curtain length, grouting curtain width and the horizontal distance between the grouting curtain and the protected structure.

4. The grouting curtain parameter design method for structural protection under blasting vibration according to claim 3, characterized in that: Step S2 includes: S21. Use ANSYS / LS-DYNA software to build a three-dimensional finite element model. The model size is set according to the actual range of the explosive and the size of the blasthole. S22. Use Lagrangian grid to divide the model, and perform grid encryption on the protection structure and its surrounding areas; S23. Setting boundary conditions, including: using non-reflecting boundary conditions around the model and at the bottom, and using free boundary conditions at the top; S24. Use the surface-surface contact algorithm to describe the soil-structure interaction and set the corresponding friction coefficient; S25. Select the material constitutive model, where the soil adopts the Drucker-Prager constitutive model and the grouting curtain adopts the CONCRETE_DAMAGE_REL3 material model, and input the corresponding physical and mechanical parameters. S26. Set the operating conditions for different parameter combinations using one of the following two methods: single factor impact analysis method, where only one major factor is changed at a time; or multi-factor orthogonal analysis method, where multiple major factors are changed simultaneously; S27. Perform simulation calculations in a three-dimensional finite element model according to the working conditions of each parameter combination, and verify the reliability of the calculation results to obtain numerical simulation results under the working conditions of different parameter combinations; S28. Based on the numerical simulation results under the working conditions of different parameter combinations, the structural vibration velocity data under the working conditions of different parameter combinations are statistically obtained.

5. The grouting curtain parameter design method for structural protection under blasting vibration according to claim 4, characterized in that: In step S27, verifying the reliability of the calculation results includes: The soil pressure, acceleration or vibration velocity results of the same point in the numerical simulation and the indoor model test are read using the post-processing software lsprepost. If the waveforms of the two are close, the peak values ​​are not much different, and the errors at each point are within 15%, the numerical simulation results are considered reliable.

6. The grouting curtain parameter design method for structural protection under blasting vibration according to claim 1, characterized in that: The grouting curtain is composed of cement mortar, rubber powder, iron powder and river sand.

7. The grouting curtain parameter design method for structural protection under blasting vibration according to claim 1, characterized in that: The protective structure includes: Ground structures, including buildings, overhead and high-voltage towers; Underground structures include underground pipelines, underground box culverts and underground tunnels.

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