Design method of proportion of low-transmittance-energy-absorbing curtain grouting materials

Abstract

The present invention proposes a method for designing the proportion of grouting materials for a low-transmittance energy-absorbing curtain, which relates to the technical fields of underground engineering and blasting engineering. The method includes the following steps: designing an orthogonal test scheme; determining the order of influence of various factors on rheological properties; determining the order of influence of various factors on physical properties through indoor experiments; obtaining the order of influence of various factors on energy absorption performance through a split-Hopkinson pressure bar test; determining the optimal proportion scheme based on the above-mentioned orthogonal test results, and verifying the rationality of the optimal proportion scheme by combining it with theoretical analysis of transflective performance; conducting blasting tests to detect the actual shock-absorbing effect of the grouting curtain using the optimal proportion scheme, and calculating its shock-absorbing rate. The technical solution of the present invention solves the difficult problems of determining the proportion of grouting materials and quantifying the shock-absorbing effect of grouting curtains in actual engineering projects. It effectively reduces the peak value of blasting vibration of buried pipelines under the action of blasting vibration, providing a guarantee for underground pipeline protection and safe construction of blasting projects.

Description

Technical Field

[0001] The invention relates to the technical field of underground engineering and blasting engineering, in particular to a method for designing the proportion of low-transmittance-energy-absorbing curtain grouting materials. Background Art

[0002] As an economical and efficient means of underground engineering excavation, the drilling and blasting method remains one of the main methods of existing underground engineering excavation due to its advantages such as fast construction speed, low cost, and strong adaptability. The drilling and blasting method is widely used in the development and construction of urban underground spaces such as tunnel projects, subway projects, and underground pipeline corridors. Unlike mountain tunnels, urban tunnel blasting usually occurs in the underground rock strata in the city center. A large number of underground pipelines are usually laid in the urban soil layer, including water supply and drainage pipelines, gas pipelines, power pipelines and other municipal lifeline projects. Therefore, during the blasting operation under the urban area and near the tunnel, the vibration disturbance effect will affect the safety of the buried pipeline structure in the overlying soil layer, which may lead to safety hazards such as pipeline deformation, joint damage, and pipe cracking, thereby posing a serious threat to the engineering safety and the protection of people's lives and property in the complex urban environment.

[0003] The seismic effect caused by blasting in urban areas is the primary problem of explosion hazards. Currently, the following three types of control measures are mainly adopted:

[0004] Take measures to protect the object: such as reinforcing the pipeline, wrapping the protective layer, etc., but this method is difficult to construct and will affect the normal use of the pipeline;

[0005] Take measures on the blast source: such as controlling the charge amount, adjusting the blasting parameters, etc., but this method will reduce the blasting efficiency and extend the construction period;

[0006] Take measures during the propagation of blasting seismic waves: such as setting shock-absorbing holes or shock-absorbing trenches.

[0007] Current research on vibration control technologies for buried pipeline blasting focuses on control measures for both the controlled object and the blast source. While these two measures have some effectiveness, they both significantly impact blasting construction. Regarding measures to attenuate the propagation of blasting seismic waves, the primary approach is to use damping holes or trenches. However, these methods present the following technical challenges: The construction of these holes or trenches is limited by site conditions and often difficult to implement in densely populated urban areas; the damping effect is significantly affected by depth and width, increasing construction difficulty and cost; the holes or trenches themselves may affect ground stability; and the damping effect is difficult to quantify, making targeted optimization impossible. Summary of the Invention

[0008] In view of this, the present invention proposes a low-transmittance-energy-absorbing curtain grouting material ratio design method to solve the technical problems of difficulty in determining the grouting curtain material ratio and quantifying the shock absorption effect in urban tunnel blasting construction, thereby effectively reducing the impact of blasting vibration on buried pipelines and providing guarantees for underground pipeline protection and safe construction of blasting projects.

[0009] The technical solution of the present invention is achieved as follows: The present invention provides a method for designing a ratio of low-transmittance-energy-absorbing curtain grouting materials, comprising:

[0010] S1. Select the basic mix material for the grouting curtain, conduct a multi-factor, multi-level orthogonal experimental design based on the basic mix material, and form n mix schemes. Pour the grouting material according to the n mix schemes, and obtain multiple samples for each mix scheme. The samples are numbered according to the mix scheme to which they belong.

[0011] S2. Perform rheological property tests on the samples and analyze the test results to determine the order of influence of various factors on the rheological properties;

[0012] S3. Conduct indoor physical and mechanical property tests on the specimens, analyze the test results, and determine the order of importance of various factors affecting the physical and mechanical properties;

[0013] S4. Conduct a split-Hopkinson pressure bar test on the sample to obtain the energy dissipation curve of the sample. Based on the energy dissipation curve, determine the order of influence of various factors on energy absorption performance;

[0014] S5. Determine the optimal ratio of the grouting material based on the results of steps S2-S4, and verify the rationality of the optimal ratio by combining the theoretical analysis of the transflective properties of the grouting material;

[0015] S6. Verify the shock absorption effect of the optimal ratio scheme through on-site blasting tests and calculate its shock absorption rate.

[0016] On the basis of the above scheme, the multi-factor multi-level orthogonal experiment in step S1 is a five-factor three-level orthogonal experiment. 27 (3 5 ) Orthogonal test table design experiment is carried out 3 3 = 27 mixing ratios, i.e. n = 27; the five factors are:

[0017] Factor A: water-cement ratio; Factor B: iron powder mesh size; Factor C: iron powder content; Factor D: rubber mesh size; Factor E: rubber content.

[0018] On the basis of the above scheme, the rheological property test in step S2 includes a water separation rate test and a viscosity test, and the physical and mechanical property test in step S3 includes a density test, a uniaxial compressive strength test, an elastic modulus test and a longitudinal wave velocity test.

[0019] Based on the above solution, step S2 includes:

[0020] S21. The water leaching rate test method is as follows: the water leaching amount is measured using a graduated cylinder, the average value of multiple samples in each mixing ratio is taken as the water leaching amount of the mixing ratio, the average value of multiple mixing ratios under the same factor is calculated, and a trend chart of the influence of each factor on the water leaching rate is plotted to analyze the order of influence of each factor on the water leaching rate;

[0021] S22. The viscosity test method is: use a standard funnel viscometer to measure and correct the data, take the average value of multiple samples in each ratio scheme as the viscosity of the ratio scheme, calculate the average value of multiple levels of ratio schemes under the same factor, and draw a trend chart of the influence of each factor on viscosity, and analyze the order of priority of the influence of each factor on viscosity.

[0022] Based on the above solution, step S3 includes:

[0023] S31. Density testing method: Use an electronic balance to measure the mass of the sample, use a vernier caliper to measure the height and diameter of the sample, calculate the sample density based on the mass-to-volume ratio, take the average value of multiple samples in each ratio as the density test result of the ratio, draw a trend chart affecting the density, and analyze the order of influence of each factor on the density.

[0024] S32. The uniaxial compressive strength test method is as follows: a uniaxial compressive test is conducted using a pressure testing machine, the maximum axial force at failure of the specimen is recorded, the uniaxial compressive strength is calculated based on the cross-sectional area of ​​the specimen, the average value of multiple specimens in each mix ratio is taken as the uniaxial compressive strength test result of that mix ratio, a trend chart of factors affecting the uniaxial compressive strength is plotted, and the order of influence of each factor on the uniaxial compressive strength is analyzed;

[0025] S33. The elastic modulus test method is as follows: during the uniaxial compression test, the axial stress and axial strain values ​​of the specimen during the elastic deformation stage are recorded, the elastic modulus is calculated based on the slope of the stress-strain curve, the average value of multiple specimens in each mix ratio is taken as the elastic modulus test result of the mix ratio, a trend graph of factors affecting the elastic modulus is plotted, and the order of influence of various factors on the elastic modulus is analyzed;

[0026] S34. The longitudinal wave velocity test method is: use a pile foundation sonic tester to measure the sound wave propagation time of the sample, calculate the longitudinal wave velocity according to the sample height, take the average value of multiple samples in each mix ratio scheme as the longitudinal wave velocity test result of the mix ratio scheme, draw a trend chart of the factors affecting the longitudinal wave velocity, and analyze the primary and secondary order of the influence of each factor on the longitudinal wave velocity.

[0027] Based on the above solution, step S4 includes:

[0028] S41. Impact loading is performed on each specimen, and the strain values ​​on the incident rod and the projection rod of the specimen during the impact process are recorded;

[0029] S42. Draw an energy dissipation curve of the sample according to the recorded strain value;

[0030] S43, calculating the energy transmittance ratio of each sample, taking the average value of multiple samples in each ratio scheme as the energy transmittance of the ratio scheme;

[0031] S44. Calculate the average value of multiple levels of the ratio scheme under the same factor, draw a trend chart of the influence of each factor on the energy transmittance, and analyze the order of importance of each factor's influence on the energy absorption performance.

[0032] Based on the above solution, in step S5, the process of determining the optimal ratio of the grouting material includes:

[0033] According to the requirements of the curtain grouting material ratio, set the energy absorption performance, density and longitudinal wave velocity as high priority;

[0034] According to the priority order of each factor's influence on water separation rate, the priority order of each factor's influence on viscosity, the priority order of each factor's influence on density, the priority order of each factor's influence on uniaxial compressive strength, the priority order of each factor's influence on elastic modulus, the priority order of each factor's influence on longitudinal wave velocity, the priority order of each factor's influence on energy absorption performance, and the priority setting, the optimal level of each factor is selected, the specific value of each factor is determined, and the best matching scheme is formed.

[0035] On the basis of the above scheme, in step S5, the rationality of the optimal ratio scheme is verified by combining the theoretical analysis of the transflective properties of the grouting material, including:

[0036] Establish a transflective calculation model for grouting materials;

[0037] Based on the transflection calculation model, the P-wave and S-wave transmission coefficients of the optimal ratio scheme at different incident angles are calculated;

[0038] Select the target incident angle and compare the transmission coefficient of the optimal ratio scheme with other ratio schemes;

[0039] The rationality of the optimal ratio scheme is verified by comparing the transmission coefficient results.

[0040] Based on the above solution, step S6 includes:

[0041] S61. Deploy acceleration sensors and earth pressure sensors during on-site blasting tests;

[0042] S62, forming a grouting curtain according to the optimal ratio scheme;

[0043] S63, respectively recording the acceleration and earth pressure data in the soil before and after the grouting curtain is formed;

[0044] S64. Compare and analyze the vibration propagation pattern and pipeline strain changes before and after grouting;

[0045] S65. Calculate the shock absorption rate of the grouting curtain based on the vibration parameters before and after grouting.

[0046] Based on the above scheme, the basic proportion materials of the grouting curtain are cement, rubber powder, iron powder and river sand.

[0047] The present invention has the following beneficial effects compared to the prior art:

[0048] 1. Through systematic experimental design, performance testing, ratio optimization, and actual verification, this invention solves the technical problems of difficulty in determining the ratio of grouting curtain materials and quantifying the shock absorption effect in actual projects. It effectively reduces the peak value of blasting vibration of buried pipelines under the action of blasting vibration, providing reliable protection for underground pipeline networks and safe construction of blasting projects.

[0049] 2. This invention uses a five-factor, three-level orthogonal experimental design method, reducing the original 243 required combinations to 27, while ensuring the representativeness of the test results, significantly reducing the experimental workload, and improving research efficiency. Through the optimized combination of five key factors: water-cement ratio, iron powder mesh size, iron powder content, rubber mesh size, and rubber content, precise control of grouting material properties is achieved;

[0050] 3. The present invention has established a comprehensive performance testing system, including the testing and analysis of rheological properties (water separation rate, viscosity), physical and mechanical properties (density, uniaxial compressive strength, elastic modulus, longitudinal wave velocity) and energy absorption performance. By analyzing the primary and secondary order of the influence of various factors on different performances, a scientific basis is provided for determining the optimal ratio scheme;

[0051] 4. The present invention combines theoretical analysis of the transflective and reflective properties of grouting materials with actual blasting tests. Through dual confirmation of theoretical calculations and practical verification, the reliability and practicality of the optimal ratio scheme are guaranteed, and the shock absorption effect of the grouting curtain is fully verified and accurately quantified. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] 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.

[0053] Figure 1 is a flow chart of a method according to an embodiment of the present invention;

[0054] Figure 2 This is a test flow chart of an embodiment of the present invention;

[0055] Figure 3 This is a trend diagram showing the influence of various factors on rheological properties according to an embodiment of the present invention;

[0056] Figure 4 This is a trend diagram showing the influence of various factors on the physical and mechanical properties of the embodiment of the present invention;

[0057] Figure 5 This is a trend diagram showing the influence of various factors on the energy absorption performance of an embodiment of the present invention;

[0058] Figure 6 Schematic diagram of a transflection calculation model according to an embodiment of the present invention;

[0059] Figure 7 A comparison diagram of transmission coefficients according to an embodiment of the present invention;

[0060] Figure 8 A schematic diagram of a blasting test design according to an embodiment of the present invention;

[0061] Figure 9 This is a comparison chart of the shock absorption effect of the blasting test of the embodiment of the present invention. DETAILED DESCRIPTION

[0062] 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.

[0063] like Figure 1 As shown, the present invention provides a method for designing a ratio of a low-transmittance-energy-absorbing curtain grouting material, comprising:

[0064] S1. Select the basic mix material for the grouting curtain, conduct a multi-factor, multi-level orthogonal experimental design based on the basic mix material, and form n mix schemes. Pour the grouting material according to the n mix schemes, and obtain multiple samples for each mix scheme. The samples are numbered according to the mix scheme to which they belong.

[0065] S2. Perform rheological property tests on the samples and analyze the test results to determine the order of influence of various factors on the rheological properties;

[0066] S3. Conduct indoor physical and mechanical property tests on the specimens, analyze the test results, and determine the order of importance of various factors affecting the physical and mechanical properties;

[0067] S4. Conduct a split-Hopkinson pressure bar test on the sample to obtain the energy dissipation curve of the sample. Based on the energy dissipation curve, determine the order of influence of various factors on energy absorption performance;

[0068] S5. Determine the optimal ratio of the grouting material based on the results of steps S2-S4, and verify the rationality of the optimal ratio by combining the theoretical analysis of the transflective properties of the grouting material;

[0069] S6. Verify the shock absorption effect of the optimal ratio scheme through on-site blasting tests and calculate its shock absorption rate.

[0070] Specifically, currently, there are a variety of grouting curtain mix ratio schemes to choose from. However, the application of grouting curtains is mainly concentrated in the fields of water isolation and reinforcement, and the performance of grouting curtain mix ratios is also uneven, which cannot be well applied to urban blasting vibration control. At the same time, the rubber material in discarded tires has excellent elastic properties and damping characteristics. Recycling and developing it into rubber-based shock-absorbing grouting materials has very important environmental protection and practical significance. Therefore, in the embodiment of the present invention, four materials, cement, rubber powder, iron powder and river sand, are selected as the basic mix ratio materials for grouting curtains, such as Figure 2 shown.

[0071] In a specific embodiment of the present invention, a five-factor three-level orthogonal design is used. If a comprehensive experimental design is selected, three 5 = 243 combinations of schemes were tested. 27 (3 5 ) Orthogonal test table design test only needs 3 3 = 27 different designs can be tested while also obtaining representative test results, significantly reducing the experimental workload. In this example, n = 27. A five-factor, three-level orthogonal header design is shown in Table 1. The five influencing factors are: Factor A: water-cement ratio; Factor B: iron powder mesh size; Factor C: iron powder content (%); Factor D: rubber mesh size; and Factor E: rubber content (%).

[0072] Table 1 Slurry ratio orthogonal test header design

[0073]

[0074] After a series of preliminary indoor tests, the values ​​are shown in Table 2.

[0075] Table 2 Orthogonal experimental design scheme for slurry ratio

[0076]

[0077]

[0078] According to the 27 mix ratio schemes shown in Table 2, the four materials were cast. Two samples were prepared for each mix ratio scheme, with the sizes Three specimens were prepared for each mix ratio, for example, two cylindrical specimens and one cubic specimen, or one cylindrical specimen and two cubic specimens. Each specimen was numbered according to the test number in Table 2. The specimens were then transferred to a standard curing chamber and cured for 7 days under standard curing conditions of 20°C and 95% humidity before testing.

[0079] Specifically, in one embodiment of the present invention, the rheological properties test in step S2 includes a water separation rate test and a viscosity test. Step S2 includes:

[0080] S21. The water leaching rate test method is as follows: the water leaching amount is measured using a graduated cylinder, the average value of multiple samples in each mixing ratio is taken as the water leaching amount of the mixing ratio, the average value of multiple mixing ratios under the same factor is calculated, and a trend chart of the influence of each factor on the water leaching rate is plotted to analyze the order of influence of each factor on the water leaching rate;

[0081] S22. The viscosity test method is: use a standard funnel viscometer to measure and correct the data, take the average value of multiple samples in each ratio scheme as the viscosity of the ratio scheme, calculate the average value of multiple levels of ratio schemes under the same factor, and draw a trend chart of the influence of each factor on viscosity, and analyze the order of priority of the influence of each factor on viscosity.

[0082] In a specific example, according to the orthogonal test scheme in Table 2, three samples are prepared for each mix ratio scheme, and the water extraction amount of each sample is recorded by a graduated cylinder. The average water extraction amount of the three samples obtained by pouring each mix ratio scheme is taken as the water extraction amount of the mix ratio scheme. According to the orthogonal test design in Tables 1 and 2, the average values ​​of the three levels under the same factor are calculated, and a trend graph of the influence of each factor on the water extraction rate is drawn based on the average values ​​of the three levels under the same factor, as shown in FIG. Figure 3As shown in (a) in . Figure 3 The horizontal axis in (a) represents the three levels corresponding to different factors. Through analysis, it can be seen that the order of priority of the factors affecting the water extraction rate is A>C>E>D>B. The water extraction rate test results of this embodiment are shown in Table 3. The range R in Table 3 refers to the difference between the maximum and minimum values. The order of priority of the influence of each factor is determined according to the size of the range R value. The larger the range, the more significant the influence of the factor.

[0083] Table 3 Results of orthogonal test on water separation rate

[0084]

[0085] The viscosity of grouting curtain material is a physical quantity that measures the viscosity of a grouting liquid, namely the internal friction resistance. The viscosity directly affects the diffusion radius of the slurry, ultimately affecting the grouting effect. Therefore, measuring the viscosity of shock-absorbing grouting curtain material is crucial for analyzing its rheological properties. The calculation formulas for the various physical quantities in the test are as follows:

[0086]

[0087] Where: T1 is the correction value of viscosity; t is the viscosity of the test water; T is the viscosity of the test sample.

[0088] The data results were measured by a standard funnel viscometer and then modified in combination with formula (1). The average viscosity of the three samples cast for each mix ratio was used as the viscosity of the mix ratio. According to the orthogonal experimental design in Tables 1 and 2, the average values ​​of the three levels under the same factor were calculated. The trend diagram of the influence of each factor on viscosity was drawn based on the average values ​​of the three levels under the same factor, as shown in the following figure: Figure 3 As shown in (b) in the figure. Through analysis, it can be seen that the order of influence of each factor on viscosity is A>C>B>E>D. The viscosity test results of this embodiment are shown in Table 4.

[0089] Table 4 Viscosity orthogonal test results

[0090]

[0091] Specifically, in one embodiment of the present invention, the physical and mechanical properties test in step S3 includes a density test, a uniaxial compressive strength test, an elastic modulus test, and a longitudinal wave velocity test. Step S3 includes:

[0092] S31. Density testing method: Use an electronic balance to measure the mass of the sample, use a vernier caliper to measure the height and diameter of the sample, calculate the sample density based on the mass-to-volume ratio, take the average value of multiple samples in each ratio as the density test result of the ratio, draw a trend chart affecting the density, and analyze the order of influence of each factor on the density.

[0093] S32. The uniaxial compressive strength test method is as follows: a uniaxial compressive test is conducted using a pressure testing machine, the maximum axial force at failure of the specimen is recorded, the uniaxial compressive strength is calculated based on the cross-sectional area of ​​the specimen, the average value of multiple specimens in each mix ratio is taken as the uniaxial compressive strength test result of that mix ratio, a trend chart of factors affecting the uniaxial compressive strength is plotted, and the order of influence of each factor on the uniaxial compressive strength is analyzed;

[0094] S33. The elastic modulus test method is as follows: during the uniaxial compression test, the axial stress and axial strain values ​​of the specimen during the elastic deformation stage are recorded, the elastic modulus is calculated based on the slope of the stress-strain curve, the average value of multiple specimens in each mix ratio is taken as the elastic modulus test result of the mix ratio, a trend graph of factors affecting the elastic modulus is plotted, and the order of influence of various factors on the elastic modulus is analyzed;

[0095] S34. The longitudinal wave velocity test method is: use a pile foundation sonic tester to measure the sound wave propagation time of the sample, calculate the longitudinal wave velocity according to the sample height, take the average value of multiple samples in each mix ratio scheme as the longitudinal wave velocity test result of the mix ratio scheme, draw a trend chart of the factors affecting the longitudinal wave velocity, and analyze the primary and secondary order of the influence of each factor on the longitudinal wave velocity.

[0096] In a specific example, the mass of the shock-absorbing grouting curtain material per unit volume is called the density of the shock-absorbing grouting curtain material. The calculation formula of the volume density method used in this test is shown in formula (2).

[0097]

[0098] Where: ρ is the sample density, g / cm 3 ; M is the sample mass, g; V is the sample volume, cm 3 .

[0099] According to the orthogonal test scheme in Table 2, three samples were prepared for each mix ratio scheme. The mass and size of the samples were measured by electronic scales and vernier calipers respectively. Then, the density of each sample was calculated according to formula (2). The average density of the three samples obtained by pouring each mix ratio scheme was taken as the density of the mix ratio scheme. According to the orthogonal test design in Tables 1 and 2, the average values ​​of the three levels under the same factor were calculated. The trend diagram of the influence of each factor on the density was drawn based on the average values ​​of the three levels under the same factor, as shown in the figure below. Figure 4As shown in (a) in the figure. Through analysis, it can be seen that the order of influence of each factor on density is A>E>D>C>B. The density test results of this embodiment are shown in Table 5.

[0100] Table 5 Density orthogonal test results

[0101]

[0102] The uniaxial compressive strength of the shock-absorbing grouting curtain material is its main ability to resist external loads. The calculation formulas of various physical quantities in the test are as follows:

[0103]

[0104] Where: σ c is the uniaxial compressive strength, MPa; P max is the maximum breaking load of the specimen, N; A is the compressive area of ​​the specimen, mm 2 ; E is the elastic modulus of the sample, MPa; σ c(50) 50% of the uniaxial compressive strength of the sample, MPa; ε h(50) Represents the axial strain corresponding to 50% of the uniaxial compressive strength.

[0105] According to the stress values ​​of the three specimens of each mix ratio recorded in the uniaxial compressive test at the time of failure and formula (3), the average uniaxial compressive strength of the three specimens of each mix ratio is obtained as the uniaxial compressive strength of the mix ratio. According to the orthogonal experimental design in Tables 1 and 2, the average values ​​of the three levels under the same factor are calculated, and the trend diagram of the influence of each factor on the uniaxial compressive strength is drawn based on the average values ​​of the three levels under the same factor, as shown in the figure below. Figure 4 As shown in (b). Through analysis, it can be seen that the order of influence of various factors on the uniaxial compressive strength of the shock-absorbing grouting curtain material is C>E>B>D>A. The uniaxial compressive strength test results of this embodiment are shown in Table 6.

[0106] Table 6 Results of uniaxial compressive strength orthogonal test

[0107]

[0108] According to the axial stress and axial strain values ​​of the three specimens of each mix ratio recorded in the uniaxial compression test and formula (4), the elastic modulus of each specimen can be calculated, and then the average elastic modulus of the three specimens of each mix ratio can be calculated as the elastic modulus of the mix ratio. According to the orthogonal experimental design in Tables 1 and 2, the average values ​​of the three levels under the same factor are calculated, and the trend diagram of the influence of each factor on the elastic modulus is drawn based on the average values ​​of the three levels under the same factor, as shown in the figure below. Figure 4As shown in (c) in the figure, the order of influence of various factors on the elastic modulus of the shock-absorbing grouting curtain material is E>C>B>D>A. The elastic modulus test results of this embodiment are shown in Table 7.

[0109] Table 7 Elastic modulus orthogonal test results

[0110]

[0111] During acoustic wave testing, a transmitting source emits high-frequency pulse waves into the medium, and a receiving system records the propagation characteristics of the waves.

[0112]

[0113] Where: u, v, and w represent the displacements in the x, y, and z directions, respectively; is the Laplace operator; G is the shear modulus; λ is the Lame coefficient; e is the volume strain symbol of the unit cell, e = ε x +ε y +ε z .

[0114] The equation for the longitudinal (P) wave velocity is:

[0115]

[0116] The measurement was carried out using the RSM-SY6 pile acoustic wave tester. The longitudinal wave velocity of each sample was then calculated according to formula (8). The average longitudinal wave velocity of the three samples of each mix ratio scheme was then calculated as the longitudinal wave velocity of the mix ratio scheme. According to the orthogonal experimental design in Tables 1 and 2, the average values ​​of the three levels under the same factor were calculated. The trend diagram of the influence of each factor on the longitudinal wave velocity was drawn based on the average values ​​of the three levels under the same factor, as shown in the figure below. Figure 4 As shown in (d) in the figure, the order of influence of various factors on the longitudinal wave velocity of the shock-absorbing grouting curtain material is E>D>C>A>B. The longitudinal wave velocity test results of this embodiment are shown in Table 8.

[0117] Table 8 Orthogonal test results of longitudinal wave velocity

[0118]

[0119] Specifically, in one embodiment of the present invention, step S4 includes:

[0120] S41. Impact loading is performed on each specimen, and the strain values ​​on the incident rod and the projection rod of the specimen during the impact process are recorded;

[0121] S42. Draw an energy dissipation curve of the sample according to the recorded strain value;

[0122] S43, calculating the energy transmittance ratio of each sample, taking the average value of multiple samples in each ratio scheme as the energy transmittance of the ratio scheme;

[0123] S44. Calculate the average value of multiple levels of the ratio scheme under the same factor, draw a trend chart of the influence of each factor on the energy transmittance, and analyze the order of importance of each factor's influence on the energy absorption performance.

[0124] In a specific example, a split Hopkinson pressure bar test was carried out, and the strain values ​​on the incident bar and the projection bar of each sample during the impact process were recorded to obtain the sample energy dissipation curve. Then, the average transmitted energy ratio of the three samples of each ratio scheme was obtained as the transmitted energy ratio of the ratio scheme. According to the orthogonal experimental design in Tables 1 and 2, the average values ​​of the three levels under the same factor were calculated, and the following results were obtained: Figure 5 The trend graph showing the impact of sample energy transmittance is shown in Figure 9. Analysis shows that the order of influence of various factors on the energy absorption performance of the shock-absorbing grouting curtain material is E > C > D > B > A. The energy transmittance test results for this example are shown in Table 9. The energy consumption of the sample is directly proportional to its shock-absorbing performance; greater energy consumption indicates better shock-absorbing performance. All five factors increase the dissipation of seismic wave energy, with water-cement ratio having the least impact.

[0125] Table 9 Energy transmittance orthogonal test results

[0126]

[0127] Specifically, in one embodiment of the present invention, in step S5, the process of determining the optimal ratio of the grouting material includes:

[0128] According to the requirements of the curtain grouting material ratio, set the energy absorption performance, density and longitudinal wave velocity as high priority;

[0129] According to the priority order of each factor's influence on water separation rate, the priority order of each factor's influence on viscosity, the priority order of each factor's influence on density, the priority order of each factor's influence on uniaxial compressive strength, the priority order of each factor's influence on elastic modulus, the priority order of each factor's influence on longitudinal wave velocity, the priority order of each factor's influence on energy absorption performance, and the priority setting, the optimal level of each factor is selected, the specific value of each factor is determined, and the best matching scheme is formed.

[0130] In step S5, the rationality of the optimal ratio scheme is verified by combining the theoretical analysis of the transflective properties of the grouting material, including:

[0131] Establish a transflective calculation model for grouting materials;

[0132] Based on the transflection calculation model, the P-wave and S-wave transmission coefficients of the optimal ratio scheme at different incident angles are calculated;

[0133] Select the target incident angle and compare and analyze the transmission coefficients of the optimal ratio scheme and other ratio schemes;

[0134] Verify the rationality of the optimal ratio scheme through the comparison results of the transmission coefficients.

[0135] In a specific example, the specific process of step S5 is as follows:

[0136] The grouting curtain material should, on the basis of meeting the fluidity of the slurry, strive to minimize the impact of blasting seismic waves on buried pipelines. Therefore, it needs to have excellent energy dissipation performance and certain strength at the same time. So, the energy absorption performance, density, and acoustic wave velocity are given priority. Considering all these factors, the final selected optimal ratio is A2B3C3D3E2, that is, the water-cement ratio is 0.85, the mesh number of iron powder is 800 mesh, the iron powder content is 15%, the mesh number of rubber is 100 mesh, and the rubber content is 20%. At this time, the bleeding rate of the slurry is small, and the viscosity is maintained at about 22 s, and the grouting of the composite slurry basically will not cause blockage. The material ratio of this scheme is shown in Table 10.

[0137] Table 10 Optimal ratio scheme F-28

[0138]

[0139] For the theoretical analysis of the transmission and reflection properties of the grouting curtain material, the fill on both sides of the grouting curtain material is simplified to a viscoelastic medium, and at the same time, the grouting curtain material conforms to the deformation law of a viscoelastic body. Based on this, the theoretical model as shown in Figure 6 can be established.

[0140] Suppose a displacement amplitude of A is excited by a seismic source in the fill medium I ip1 , and its displacement function can be expressed by formula (9).

[0141]

[0142] Based on this function, the transmission and reflection of stress waves are as follows: in the region where z < 0 (i.e., in medium I), a reflected P-wave with an amplitude of A rp1 and a SV-wave with an amplitude of B rs1 are generated. In the region where 0 < z < h, a P-wave with an amplitude of A tp2 and a SV-wave with an amplitude of B ts2 are generated, as well as a reflected P-wave with an amplitude of A rp2 and a reflected S-wave with an amplitude of B rs2 ; in the region where z > h, a transmitted P-wave with an amplitude of A tp3 and a transmitted SV-wave with an amplitude of B ts3 are generated.

[0143] In a viscoelastic medium, the position vector and propagation attenuation vector are introduced, and the position vector r = xi1 + yi2. The potential function in the medium can be expressed as Equation (10). i1 and i2 are unit vectors in the x and y directions, respectively. P p and A p They represent the propagation vector and attenuation vector of the longitudinal wave, P s and A s represent the propagation vector and attenuation vector of the shear wave respectively.

[0144]

[0145]

[0146] In soil medium I, the total potential function is:

[0147]

[0148] In concrete medium II, the total potential function is:

[0149]

[0150] In soil medium III, the total potential function is:

[0151]

[0152] According to Snell's law, the wave numbers of all seismic waves in the z direction are equal, that is:

[0153]

[0154] The boundary conditions of this model can be regarded as the continuity of the tangential shear stress and tangential displacement at the two interfaces, and the continuity of the normal stress and normal displacement. The boundary conditions in this case are expressed as shown in Equations (16) and (17):

[0155] 1. When z = 0

[0156]

[0157] 2. When z = h

[0158]

[0159] Where u x Indicates horizontal displacement, u z represents the vertical displacement, σ zz represents normal stress, τ zx Represents shear stress, where the units are selected using the International System of Units, the unit of displacement is m, and the unit of stress is Pa.

[0160] The stress-strain relationship is:

[0161]

[0162] Where θ = ε y +ε x is the relative volume change; γ is the shear strain.

[0163] Substituting the optimal mix parameters selected in Table 10 into the simultaneous equations, we can calculate the transmission and reflection coefficients of a P-wave incident from soil medium I, propagating through concrete medium II, and finally into clay medium III as the incident angle changes. This indicates that when the blasting seismic wave's angle of incidence is greater than 40°, the transmission coefficient of the shock-absorbing grouting curtain material begins to decrease rapidly, reaching zero at an angle of incidence of 90°, and then undergoing total reflection at 90°. The transmission coefficient of the S-wave generated by the incident P-wave of the blasting seismic wave passing through media I and II and at the interface between media II and III reaches its maximum at 60°, reaching 0.19, which is less than the transmission coefficient of the P-wave.

[0164] Considering the actual site engineering, the P-wave transmission coefficient at 20° is selected for comparison, such as Figure 7 Through comparative analysis, we can see that the selected optimal ratio scheme (F-28) has a smaller transflective coefficient and better transflective ability, which also confirms that the selected ratio is more appropriate.

[0165] Specifically, in one embodiment of the present invention, step S6 includes:

[0166] S61. Deploy acceleration sensors and earth pressure sensors during on-site blasting tests;

[0167] S62, forming a grouting curtain according to the optimal ratio scheme;

[0168] S63, respectively recording the acceleration and earth pressure data in the soil before and after the grouting curtain is formed;

[0169] S64. Compare and analyze the vibration propagation pattern and pipeline strain changes before and after grouting;

[0170] S65. Calculate the shock absorption rate of the grouting curtain based on the vibration parameters before and after grouting.

[0171] In a specific example, in order to further study the shock absorption performance of the grouting curtain material on the blasting vibration of the buried pipeline, this embodiment carries out a blasting test. The blasting test design diagram is shown in FIG. Figure 8 The acceleration and earth pressure data in the soil before and after the grouting curtain is formed are statistically analyzed and the statistical results are shown in Table 11.

[0172] Table 11 Acceleration and soil pressure before and after grouting

[0173]

[0174] The data in Table 11 show that acceleration and earth pressure increase as the distance from the blast center decreases, consistent with the attenuation of blasting vibration waves. Before and after grouting, the acceleration and earth pressure values ​​at measuring points J3, T3, and J4, T4 show significant changes, indicating that the grouting curtain absorbs and reflects the seismic waves generated by the blasting.

[0175] The strain of the measuring points of the protected objects (buried pipelines) before and after grouting were statistically sorted out, and the statistical data results are shown in Table 12 and Figure 9 As shown in Table 12 and Figure 9 The data shows a significant attenuation of strains before and after the pipeline, consistent with the acceleration and earth pressure data previously described, with an attenuation of approximately 40%. Therefore, grouting curtain materials can help attenuate the effects of blasting on buried pipelines, contributing to their safety.

[0176] Table 12 Pipeline strain before and after grouting

[0177]

[0178] It can be seen that the shock-absorbing performance of the grouting curtain material is significant. The grouting curtain can attenuate about 40% of the pipeline strain and attenuate the seismic waves generated by the blasting to a large extent. It plays a certain protective role in protecting the safety of buried pipelines and has practical engineering significance.

[0179] 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 method for designing a ratio of low-transmittance and energy-absorbing curtain grouting materials, characterized in that: include: S1. Select the basic mix material for the grouting curtain, conduct a multi-factor, multi-level orthogonal experimental design based on the basic mix material, and form n mix schemes. Pour the grouting material according to the n mix schemes, and obtain multiple samples for each mix scheme. The samples are numbered according to the mix scheme to which they belong. The multi-factor multi-level orthogonal experiment in step S1 is a five-factor three-level orthogonal experiment. 27 (3 5 ) Orthogonal test table design experiment is carried out 3 3 =27 kinds of mixing ratio schemes, that is, n=27; the five factors are: Factor A: water-cement ratio; Factor B: iron powder mesh size; Factor C: iron powder content; Factor D: rubber mesh size; Factor E: rubber content; S2. Perform rheological property tests on the samples and analyze the test results to determine the order of influence of various factors on the rheological properties; S3. Conduct indoor physical and mechanical property tests on the specimens, analyze the test results, and determine the order of importance of various factors affecting the physical and mechanical properties; S4. Conduct a split-Hopkinson pressure bar test on the sample to obtain the energy dissipation curve of the sample. Based on the energy dissipation curve, determine the order of influence of various factors on energy absorption performance; S5. Determine the optimal ratio of the grouting material based on the results of steps S2-S4, and verify the rationality of the optimal ratio by combining the theoretical analysis of the transflective properties of the grouting material; S6. Verify the shock absorption effect of the optimal ratio scheme through on-site blasting tests and calculate its shock absorption rate.

2. The method for designing a ratio of a low-transmittance-energy-absorbing curtain grouting material according to claim 1, wherein: The rheological property test in step S2 includes a water separation rate test and a viscosity test, and the physical and mechanical property test in step S3 includes a density test, a uniaxial compressive strength test, an elastic modulus test, and a longitudinal wave velocity test.

3. The method for designing a ratio of a low-transmittance-energy-absorbing curtain grouting material according to claim 2, wherein: Step S2 includes: S21. The water leaching rate test method is as follows: the water leaching amount is measured using a graduated cylinder, the average value of multiple samples in each mixing ratio is taken as the water leaching amount of the mixing ratio, the average value of multiple mixing ratios under the same factor is calculated, and a trend chart of the influence of each factor on the water leaching rate is plotted to analyze the order of influence of each factor on the water leaching rate; S22. The viscosity test method is: use a standard funnel viscometer to measure and correct the data, take the average value of multiple samples in each ratio scheme as the viscosity of the ratio scheme, calculate the average value of multiple levels of ratio schemes under the same factor, and draw a trend chart of the influence of each factor on viscosity, and analyze the order of priority of the influence of each factor on viscosity.

4. The method for designing a ratio of a low-transmittance-energy-absorbing curtain grouting material according to claim 2, wherein: Step S3 includes: S31. Density testing method: Use an electronic balance to measure the mass of the sample, use a vernier caliper to measure the height and diameter of the sample, calculate the sample density based on the mass-to-volume ratio, take the average value of multiple samples in each ratio as the density test result of the ratio, draw a trend chart affecting the density, and analyze the order of influence of each factor on the density. S32. The uniaxial compressive strength test method is as follows: a uniaxial compressive test is conducted using a pressure testing machine, the maximum axial force at failure of the specimen is recorded, the uniaxial compressive strength is calculated based on the cross-sectional area of ​​the specimen, the average value of multiple specimens in each mix ratio is taken as the uniaxial compressive strength test result of that mix ratio, a trend chart of factors affecting the uniaxial compressive strength is plotted, and the order of influence of each factor on the uniaxial compressive strength is analyzed; S33. The elastic modulus test method is as follows: during the uniaxial compression test, the axial stress and axial strain values ​​of the specimen during the elastic deformation stage are recorded, the elastic modulus is calculated based on the slope of the stress-strain curve, the average value of multiple specimens in each mix ratio is taken as the elastic modulus test result of the mix ratio, a trend graph of factors affecting the elastic modulus is plotted, and the order of influence of various factors on the elastic modulus is analyzed; S34. The longitudinal wave velocity test method is: use a pile foundation sonic tester to measure the sound wave propagation time of the sample, calculate the longitudinal wave velocity according to the sample height, take the average value of multiple samples in each mix ratio scheme as the longitudinal wave velocity test result of the mix ratio scheme, draw a trend chart of the factors affecting the longitudinal wave velocity, and analyze the primary and secondary order of the influence of each factor on the longitudinal wave velocity.

5. The method for designing a ratio of a low-transmittance-energy-absorbing curtain grouting material according to claim 1, wherein: Step S4 includes: S41. Impact loading is performed on each specimen, and the strain values ​​on the incident rod and the projection rod of the specimen during the impact process are recorded; S42. Draw an energy dissipation curve of the sample according to the recorded strain value; S43, calculating the energy transmittance ratio of each sample, taking the average value of multiple samples in each ratio scheme as the energy transmittance of the ratio scheme; S44. Calculate the average value of multiple levels of the ratio scheme under the same factor, draw a trend chart of the influence of each factor on the energy transmittance, and analyze the order of importance of each factor's influence on the energy absorption performance.

6. The method for designing a ratio of a low-transmittance-energy-absorbing curtain grouting material according to claim 2, wherein: In step S5, the process of determining the optimal ratio of the grouting material includes: According to the requirements of the curtain grouting material ratio, set the energy absorption performance, density and longitudinal wave velocity as high priority; According to the priority order of each factor's influence on water separation rate, the priority order of each factor's influence on viscosity, the priority order of each factor's influence on density, the priority order of each factor's influence on uniaxial compressive strength, the priority order of each factor's influence on elastic modulus, the priority order of each factor's influence on longitudinal wave velocity, the priority order of each factor's influence on energy absorption performance, and the priority setting, the optimal level of each factor is selected, the specific value of each factor is determined, and the best matching scheme is formed.

7. The method for designing a ratio of a low-transmittance-energy-absorbing curtain grouting material according to claim 2, wherein: In step S5, the rationality of the optimal ratio scheme is verified by combining the theoretical analysis of the transflective properties of the grouting material, including: Establish a transflective calculation model for grouting materials; Based on the transflection calculation model, the P-wave and S-wave transmission coefficients of the optimal ratio scheme at different incident angles are calculated; Select the target incident angle and compare the transmission coefficient of the optimal ratio scheme with other ratio schemes; The rationality of the optimal ratio scheme is verified by comparing the transmission coefficient results.

8. The method for designing a ratio of a low-transmittance-energy-absorbing curtain grouting material according to claim 1, wherein: Step S6 includes: S61. Deploy acceleration sensors and earth pressure sensors during on-site blasting tests; S62, forming a grouting curtain according to the optimal ratio scheme; S63, respectively recording the acceleration and earth pressure data in the soil before and after the grouting curtain is formed; S64. Compare and analyze the vibration propagation pattern and pipeline strain changes before and after grouting; S65. Calculate the shock absorption rate of the grouting curtain based on the vibration parameters before and after grouting.

9. The method for designing a ratio of a low-transmittance-energy-absorbing curtain grouting material according to claim 1, wherein: The basic mix materials of the grouting curtain are cement, rubber powder, iron powder and river sand.

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