Method for testing grouting curtain model system for underground pipeline vibration control

Abstract

This invention proposes a method for testing a grouting curtain model system for underground pipeline vibration control, relating to the fields of underground engineering and blasting engineering technology. The method includes: constructing a test model based on similarity theory, including determining a geometric similarity ratio, constructing a model test box with a shock-absorbing boundary, and reserving grouting locations within the test box; selecting model test materials, including selecting fill materials appropriate to the project site, determining buried pipeline specifications, preparing explosive packs for simulated blasting, and preparing grouting curtain materials according to a predetermined ratio; arranging a measurement system and conducting tests, including arranging strain measurement points on the pipeline surface, deploying acceleration sensors and earth pressure sensors in the soil, and using a dynamic signal acquisition system to record measurement data during the simulated blasting process. This invention systematically reveals the vibration reduction mechanism of grouting curtains in controlling blasting vibration in urban underground pipelines, providing a theoretical basis and technical support for urban infrastructure safety.

Description

Technical Field

[0001] The invention relates to the technical field of underground engineering and blasting engineering, in particular to a method of a grouting curtain model test system for underground pipeline vibration control. Background Art

[0002] As a vital component of urban infrastructure, underground pipelines face numerous safety risks during urban construction and engineering projects. Under dynamic loads such as urban blasting and earthquakes, underground pipelines are particularly susceptible to severe vibration damage, threatening the integrity of the pipelines and the safety of urban infrastructure. Existing vibration control technologies primarily include traditional vibration protection, foundation treatment, and grouting reinforcement. However, these methods generally suffer from key technical deficiencies, including high passivity, limited protection effectiveness, high costs, and difficulty in construction.

[0003] Traditional vibration protection technologies primarily rely on the seismic resistance of the pipeline material itself, such as selecting high-strength pipes and increasing pipe wall thickness. However, relying solely on the pipeline's inherent performance is insufficient to fundamentally reduce the impact of external vibration. Ground treatment technologies, such as soil compaction and the addition of shock-absorbing materials, reduce vibration by improving the physical and mechanical properties of the soil surrounding the pipeline. However, these technologies are costly, difficult to implement, and offer inconsistent long-term results. Grouting reinforcement, an emerging vibration control method, creates a "shock-absorbing curtain" by injecting specific materials around the pipeline. However, it currently faces technical bottlenecks, including a lack of systematic research on grouting material ratios and a lack of in-depth understanding of vibration reduction mechanisms.

[0004] In view of the limitations of the above-mentioned existing technologies, there is an urgent need to develop a model test method that can systematically evaluate the vibration control effect of grouting curtains, so as to reveal its mechanism of action and provide a theoretical basis and technical support for the safety protection of urban underground pipelines. Summary of the Invention

[0005] In view of this, the present invention proposes a method for a grouting curtain model test system for underground pipeline vibration control. By establishing a scientific and accurate grouting curtain model test system for underground pipeline vibration control, the vibration reduction mechanism of the grouting curtain in the blasting vibration control of urban underground pipelines is systematically revealed. By comparing the experimental design, measurement system and grouting curtain material ratio, the protective effect of the grouting curtain on the underground pipeline is comprehensively evaluated, providing a theoretical basis and technical support for the safety of urban infrastructure, and ultimately achieving the effective reduction of the risk of vibration damage to underground pipelines under dynamic loads such as blasting, thereby protecting the structural integrity and safety of buried pipelines.

[0006] The technical solution of the present invention is achieved as follows: The present invention provides a method for a grouting curtain model test system for underground pipeline vibration control, comprising:

[0007] S1. Produce a test model based on similarity theory, including: determining a geometric similarity ratio, producing a model test box with a shock-absorbing boundary, and reserving a grouting position in the test box;

[0008] S2. Selecting model test materials, including: selecting fill materials appropriate to the project site, determining buried pipeline specifications, preparing explosive packs for simulated blasting, and preparing grouting curtain materials according to a predetermined ratio;

[0009] S3. Arrange the measurement system and conduct tests, including: arranging strain measurement points on the pipeline surface, placing acceleration sensors and soil pressure sensors in the soil, and using a dynamic signal acquisition system to record measurement data during the simulated blasting process.

[0010] On the basis of the above technical solution, preferably, the method further includes setting up a control experimental step: conducting a first blasting test in a non-grouting state and recording the data, then injecting slurry into the reserved position to form a grouting curtain, and conducting a second blasting test and recording the data after it solidifies, and evaluating the protective effect of the grouting curtain by comparing and analyzing the measurement data before and after grouting.

[0011] On the basis of the above technical solution, preferably, silty clay is used as the filling material, PVC pipes are used as the buried pipelines, and customized black powder is used as the explosive bag for simulated blasting, and the vibration propagation law in the filling is verified through the deflagration test.

[0012] Based on the above technical solution, preferably, step S1 includes:

[0013] S11. Determine the geometric similarity ratio based on the first similarity theorem and the second similarity theory, and thereby determine the elastic modulus similarity ratio, bulk density similarity ratio, Poisson's ratio and friction angle similarity ratio, as well as the static and dynamic response similarity ratios. The first similarity theorem states that similar physical phenomena must obey the same objective laws, and the second similarity theorem states that physical phenomena of the same type must be similar when the single-valued conditions are similar and the similarity criteria composed of the physical quantities in the single-valued conditions are correspondingly equal.

[0014] S12. Based on the characteristics of urban blasting projects, a 2×0.5×0.5m model test box was fabricated using steel and acrylic plates. Sponge was attached to the inner wall of the model test box as a shock-absorbing layer, and sponge pads were added around the perimeter and bottom of the model test box to absorb seismic waves generated by the blasting.

[0015] S13. Prepare fill soil according to the set mix ratio, fill it into the model test box to a height of 0.25m and level it;

[0016] S14. Reserve a grouting position in the model test box, which is located between the medicine bag and the buried pipeline.

[0017] Based on the above technical solution, preferably, in step S3, the arrangement of the measurement system includes:

[0018] Strain measuring points are arranged on both sides of the buried pipeline, numbered AF, and each measuring point is equipped with circumferential and axial strain gauges; acceleration measuring points J1-J5 and soil pressure measuring points T1-T5 are arranged on the plane connecting the explosive bag and the buried pipeline; the strain gauges, acceleration sensors and soil pressure sensors are connected to the dynamic signal acquisition system through test lines.

[0019] On the basis of the above technical solution, preferably, the sampling frequency of the dynamic signal acquisition system is 10000 Hz, which is used to collect strain data of the buried pipeline, soil pressure and acceleration data in the soil.

[0020] On the basis of the above technical solution, preferably, the strain gauge adopts BF120-3BA type with a measuring range of 20000με; the acceleration sensor adopts ICP / IEPE type vibration acceleration sensor, and the soil pressure sensor adopts DMTY type sensor.

[0021] On the basis of the above technical solution, preferably, the proportion of the grouting curtain material is: water-cement ratio 0.85, 800 mesh iron powder content 15%, 100 mesh rubber content 20%.

[0022] On the basis of the above technical solution, preferably, in the control experimental steps, a grouting machine is used to inject slurry into the reserved position with a grouting pressure of 0.7 MPa to form a mixed grouting area; and a second blasting test is conducted after the grouting material is allowed to fully solidify after standing for 7 days.

[0023] On the basis of the above technical solution, preferably, the protective effect of the grouting curtain is evaluated by comparing and analyzing the measurement data before and after grouting, specifically including:

[0024] Plot the curves of acceleration and earth pressure changing with the distance from the explosion center, and compare and analyze the changing patterns of the values ​​at each measuring point before and after grouting; calculate the circumferential strain and axial strain of the buried pipeline measuring point AF before and after grouting, and plot the strain distribution curve; calculate the attenuation rate of various data before and after grouting; and comprehensively evaluate the protective effect of the grouting curtain: when the acceleration and earth pressure at the grouting curtain location show a significant decrease, and the overall attenuation rate of the buried pipeline strain reaches the expected value, it is determined that the grouting curtain has a good protective effect.

[0025] The present invention has the following beneficial effects compared to the prior art:

[0026] (1) This paper proposes a grouting curtain model test system method for underground pipeline vibration control. Through scientific experimental design and rigorous control experiments, it systematically reveals the vibration reduction mechanism of grouting curtain in urban underground pipeline vibration control, and achieves effective suppression of underground pipeline blasting vibration. This method establishes a complete model test technology route, providing a theoretical basis and technical support for the safety protection of urban underground pipelines;

[0027] (2) This invention uses the first and second similarity theorems to accurately determine multi-dimensional similarity parameters such as geometric similarity ratio, elastic modulus similarity ratio, and bulk density similarity ratio, ensuring the scientific nature and accuracy of the model test. By strictly controlling the similarity conditions, the laboratory-scale model can be highly simulated to the actual project, improving the reliability of underground pipeline vibration control research;

[0028] (3) The present invention designs a model test box with a shock-absorbing boundary. A sponge shock-absorbing layer is attached to the inner wall and surrounding of the test box, which effectively absorbs the seismic waves generated by the blast, significantly reduces the impact of boundary conditions on the test results, and improves the accuracy of the test data.

[0029] (4) The present invention constructs a multi-parameter, high-precision measurement system. By precisely arranging strain measuring points, acceleration sensors, and soil pressure sensors on the pipeline surface and in the soil, and adopting a 10,000 Hz high-frequency dynamic signal acquisition system, it achieves comprehensive and accurate monitoring of the vibration process of underground pipelines. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] 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.

[0031] Figure 1 is a flow chart of a method according to an embodiment of the present invention;

[0032] Figure 2 This is a diagram of a buried pipeline model test device according to an embodiment of the present invention;

[0033] Figure 3 This is a diagram of a drug package experiment according to an embodiment of the present invention;

[0034] Figure 4 This is a peak pressure diagram of a deflagration experiment according to an embodiment of the present invention;

[0035] Figure 5 This is a diagram showing the measured acceleration and soil pressure distribution before and after grouting in an embodiment of the present invention;

[0036] Figure 6 This is a measured strain distribution diagram of the pipeline monitoring points before and after grouting according to an embodiment of the present invention. DETAILED DESCRIPTION

[0037] 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.

[0038] like Figure 1 As shown, the present invention provides a method for a grouting curtain model test system for underground pipeline vibration control, comprising:

[0039] S1. Produce a test model based on similarity theory, including: determining a geometric similarity ratio, producing a model test box with a shock-absorbing boundary, and reserving a grouting position in the test box;

[0040] S2. Selecting model test materials, including: selecting fill materials appropriate to the project site, determining buried pipeline specifications, preparing explosive packs for simulated blasting, and preparing grouting curtain materials according to a predetermined ratio;

[0041] S3. Arrange the measurement system and conduct tests, including: arranging strain measurement points on the pipeline surface, placing acceleration sensors and soil pressure sensors in the soil, and using a dynamic signal acquisition system to record measurement data during the simulated blasting process.

[0042] Specifically, in one embodiment of the present invention, step S1 includes:

[0043] S11. Determine the geometric similarity ratio based on the first similarity theorem and the second similarity theory, and thereby determine the elastic modulus similarity ratio, bulk density similarity ratio, Poisson's ratio and friction angle similarity ratio, as well as the static and dynamic response similarity ratios. The first similarity theorem states that similar physical phenomena must obey the same objective laws, and the second similarity theorem states that physical phenomena of the same type must be similar when the single-valued conditions are similar and the similarity criteria composed of the physical quantities in the single-valued conditions are correspondingly equal.

[0044] S12. Based on the characteristics of urban blasting projects, a 2×0.5×0.5m model test box was fabricated using steel and acrylic plates. Sponge was attached to the inner wall of the model test box as a shock-absorbing layer, and sponge pads were added around the perimeter and bottom of the model test box to absorb seismic waves generated by the blasting.

[0045] S13. Prepare fill soil according to the set mix ratio, fill it into the model test box to a height of 0.25m and level it;

[0046] S14. Reserve a grouting position in the model test box, which is located between the medicine bag and the buried pipeline.

[0047] Specifically, the test model fabrication of the present invention mainly includes two key steps: determining the similarity ratio and fabricating the test box. Based on the spatial relative relationship between the buried pipeline on site and the engineering site, and taking into account the model test similarity theory and the operability of the model test, the similarity ratio of the model similarity material and basic physical quantities is obtained. Based on the influence range of the stress redistribution of the buried pipeline under the influence of blasting vibration, the specifications and dimensions of the model box are determined using the model similarity theory. The specific operation is as follows:

[0048] a. Determine the similarity ratio

[0049] Parameter design is carried out according to the similarity criteria of the first and second similarity theories, and the geometric similarity ratio of the prototype geometric dimensions and the device geometric dimensions in the actual project is determined to be L. According to the geometric similarity ratio, the buried pipeline and the engineering site are designed according to 1 / L of the prototype size; the gravity acceleration similarity ratio Cg=1, the density similarity ratio Cρ=1, the bulk density similarity ratio Cγ=1, and the similarity design of the structural parameters of the rock and soil mass is based on the geometric similarity ratio and the bulk density similarity ratio to achieve full similarity of Poisson's ratio and friction angle. The elastic modulus is designed according to the similarity ratio L of the elastic modulus of the prototype rock mass. The first similarity theorem is: physical phenomena that are similar to each other must obey the same objective law. If the law can be expressed by an equation, the physical equations must be exactly the same, and the corresponding similarity criteria must be numerically equal: the second similarity theorem is: for all physical phenomena of the same type, when the single-valued conditions are similar and the corresponding similarity criteria composed of the physical quantities in the single-valued conditions are equal, then these phenomena must be similar.

[0050] The specific design is as follows:

[0051] Geometric similarity ratio: CL=L;

[0052] Elastic modulus similarity ratio: CE = 1;

[0053] Bulk density similarity ratio: Cγ=1;

[0054] Poisson's ratio, friction angle similarity ratio:

[0055] The similarity ratios of static and dynamic responses are determined based on:

[0056] According to the dimensional relationship: pressure = gravity × length, the pressure similarity ratio Cξ = Cγ × CL = L;

[0057] Stress similarity ratio Cσ=L;

[0058] Velocity similarity ratio Cv = CL / Ct;

[0059] Time similarity ratio Ct = C0.5 s / C 0.5 a ;

[0060] Displacement similarity ratio Cs = CL;

[0061] Acceleration similarity ratio Ca = 1;

[0062] b. Make a test chamber and determine the boundary conditions

[0063] The actual dimensions of the project site were 15m x 6m. The buried pipeline was located 2m below a silty clay layer 4-5m thick. Underlying this layer was a strongly weathered silty sandstone layer 8-10m thick. Based on the characteristics of urban blasting projects and the need for simple and time-saving fabrication, the model geometry ratio was determined to be L. A 2 x 0.5 x 0.5m model box was fabricated from steel and acrylic sheets. Fill soil was prepared according to the specified mix ratio, placed within the model box to a height of approximately 0.25m, and then leveled. To ensure that the model test boundary simulated actual boundary conditions as closely as possible, five sponge pads were added around the perimeter and bottom of the model to absorb seismic waves generated by the blasting.

[0064] Specifically, in one embodiment of the present invention, silty clay is used as the backfill material, PVC pipes are used as the buried pipelines, and customized black powder is used as the explosive bag for simulated blasting. The vibration propagation law in the backfill is verified through a deflagration test.

[0065] In this embodiment, step S1 specifically includes:

[0066] a. Determine the fill material

[0067] The test selected silty clay from a full-scale in-situ blasting test site adjacent to a buried pipeline. The soil layer is mainly composed of highly saturated soft soil with extremely uneven structural composition. The physical parameters are shown in Table 1.

[0068] Table 1 Fill material parameters

[0069]

[0070] b. Determine the buried pipeline

[0071] The experiment took PVC pipes as the research object and arranged the pipes in Figure 2 At 1 location, a buried PVC pipe with a diameter of D = 9 cm, a wall thickness of δ = 0.2 cm, and a length of L = 45 cm was selected. The physical and mechanical parameters are shown in Table 2.

[0072] Table 2 Pipe material parameters

[0073]

[0074] c. Determine the simulated drug package

[0075] Customize a certain amount of black powder in the fireworks factory and conduct a deflagration test to verify it, such as Figure 3 As shown, including soil propagation test and deflagration test, Figure 3 (a) shows the arrangement of soil propagation test, with monitoring points #1, #2, #3, #4, and #5 around the explosion source. Figure 3 (b) shows the arrangement of the deflagration experiment. The propagation law of the explosion in the fill is verified by the experiment. The explosion pressure and soil pressure are measured. The peak pressure is measured. Figure 4 The measured soil pressure is shown in Table 3. The test results show that the blast load curve well restores the blast vibration load characteristics of the field test, the soil pressure values ​​at different monitoring points are stable, and the data from the three blasting tests have good consistency, meeting the requirements of the model test.

[0076] Table 3 Earth pressure values ​​from deflagration tests

[0077] Monitoring point number Soil pressure at first blasting / MPa Second blasting soil pressure / MPa Soil pressure during the third blasting / MPa #1 0.122 0.112 0.108 #2 0.113 0.104 0.098 #3 0.103 0.090 0.097 #4 0.043 0.309 0.038 #5 0.040 0.036 0.035

[0078] d. Determine grouting material

[0079] Through orthogonal experimental design, indoor mechanical testing, and data analysis, a shock-absorbing grouting curtain material suitable for buried pipelines was successfully developed. The test results showed that the water-cement ratio had the greatest impact on the slurry's water separation rate and viscosity, while the water-cement ratio and rubber content had the greatest influence on the density of the shock-absorbing grouting curtain material. Furthermore, the rubber content had the greatest impact on the uniaxial compressive strength, elastic modulus, dynamic energy absorption, and acoustic wave velocity of the shock-absorbing grouting curtain material. Based on these analysis results, the optimal grouting curtain ratio was determined to be: a water-cement ratio of 0.85, an iron powder mesh size of 800 mesh, an iron powder content of 15%, a rubber mesh size of 100 mesh, and a rubber content of 20%.

[0080] Specifically, in one embodiment of the present invention, in step S3, the arrangement of the measurement system includes:

[0081] Strain measurement points, numbered AF, were placed on both sides of the buried pipeline. Circumferential and axial strain gauges were installed at each point. Acceleration measurement points J1-J5 and earth pressure measurement points T1-T5 were located on the plane connecting the explosive package and the buried pipeline. The strain gauges, accelerometers, and earth pressure sensors were connected to a dynamic signal acquisition system via test cables. The dynamic signal acquisition system, with a sampling frequency of 10,000 Hz, collected strain data on the buried pipeline, as well as earth pressure and acceleration data in the soil.

[0082] Specifically, in this embodiment, a buried pipeline model test device is first set up, as shown in the figure below. Figure 2 As shown, Figure 2 (a) is a top view of the device. Figure 2(b) is a side view. Figure 2 In the figure, number 1 indicates the PVC pipe used for the test, number 2 indicates the arrangement of strain gauges, number 3 indicates the grouting area, number 4 indicates the accelerometer, number 5 indicates the earth pressure cell, and number 6 indicates the blasting charge. Figure 2 As shown in the figure, the PVC pipe used for the test is arranged in the center of the test box. The pipe diameter is 25 cm and it is arranged 15 cm away from the left edge of the test box. Six strain gauges are arranged on the surface of the pipe, marked as A, B, C, D, E, and F. The strain gauges are evenly distributed along the circumference of the pipe, namely circumferential and axial strain gauges. The spacing between adjacent strain gauges is 10 cm, which is used to measure the strain response of the pipe under the action of blasting vibration. The grouting area is located 60 cm to the right of the pipe and is marked with a dotted line box to indicate the reserved grouting curtain construction area for subsequent grouting protection. Test: Accelerometers were placed every 25 cm along the line connecting the explosive charge to the pipeline. An earth pressure cell was placed adjacent to the accelerometer to measure soil stress. The accelerometer and the earth pressure cell monitoring surface were aligned with the blasting surface. Accelerometer and earth pressure measuring points were arranged on the plane connecting the explosive charge and the pipeline. Starting from the explosive charge, the measuring points were numbered J1, J2, J3, J4, and J5, and T1, T2, T3, T4, and T5. The explosive charge was located at the far right end of the test chamber, 20 cm from the right edge and aligned with the pipeline centerline, simulating the blasting vibration source. The complete layout dimensions from left to right were: 15 cm (left margin) + 25 cm (pipe diameter) + 60 cm (to the grouting area) + 25 cm × 3 (measuring point spacing) + 20 cm (right margin). The measuring points were evenly spaced 25 cm apart to ensure continuity and comparability of data collection.

[0083] This arrangement effectively captures key physical quantities during blast vibration propagation, including pipeline strain response, soil acceleration changes, and soil pressure transmission characteristics. Furthermore, the reserved grouting area facilitates subsequent research into the protective effectiveness of the grouting curtain.

[0084] Subsequently, dynamic strain data was used to investigate the stress and strain characteristics of buried pipelines under the influence of blasting seismic waves, a crucial component of the successful measurement experiment. The experiment utilized the DH5960 ultra-high-speed dynamic signal acquisition system and the DH3817 dynamic strain data acquisition system, leveraging their high-speed and precise measurement capabilities to collect strain data from the buried pipelines and analyze the multiple sets of dynamic strain measurements. The strain gauge used was the Xingdongfang BF120-3BA rosette with a range of 20,000 με. The accelerometer used in the experiment was a Shanghai Chengke ICP / IEPE vibration acceleration sensor. The earth pressure cell used was a DMTY earth pressure cell manufactured by Nanjing Danmo Electronic Technology.

[0085] Before blasting, connect the sensor's pre-recorded data cable to the signal acquisition instrument. Then, conduct a blasting model test according to the experimental plan, collecting data such as buried pipeline strain, soil pressure, and acceleration. The sampling frequency for the blasting experiment was set to 10,000 Hz.

[0086] Before the model explosives are detonated, the recording instruments at all monitoring points are turned on to record the data of the initial monitoring point. All monitoring and recording instruments are kept turned on to continuously monitor the entire model simulated blasting vibration process until all monitoring data are stable, and then the entire monitoring process is ended.

[0087] Specifically, when arranging strain measurement points, the strain gauge surface was pre-polished and glued. The strain gauge surface was insulated and connected to the Donghua DH5956 dynamic signal acquisition and analysis system via test cables. The pipeline was wrapped with plastic wrap to prevent fill soil from entering the pipeline and affecting the test results. Accelerometers and earth pressure cells were deployed, ensuring that the accelerometer and earth pressure cell monitoring surfaces were aligned with the blast surface. Test cables were connected to the DH5956 dynamic signal acquisition instrument and DH3817 dynamic strain data acquisition system to determine the position of the explosive charge. This allowed the stress wave generated by the explosion to propagate toward the pipeline, blocking the blasthole and providing a protective cover. The DH5956 dynamic signal acquisition instrument and DH3817 dynamic strain data acquisition system were triggered synchronously via an external trigger device. After the test cables and inflation tubes were deployed, silty clay was filled to ensure close contact and compaction of the buried pipeline fill soil.

[0088] Specifically, the present invention uses a controlled experiment to evaluate the protective effect of a grouting curtain on underground pipelines. The steps include: conducting a first blasting test without grouting and recording the data; then injecting slurry into a reserved location to form a grouting curtain; after the grouting curtain solidifies, conducting a second blasting test and recording the data; and evaluating the protective effect of the grouting curtain by comparing and analyzing the measured data before and after grouting. Furthermore, a grouting machine is used to inject slurry into the reserved location at a grouting pressure of 0.7 MPa to form a mixed grouting area; and after the grouting material is allowed to fully solidify for 7 days, a second blasting test is conducted.

[0089] The protective effect of the grouting curtain was evaluated by comparing and analyzing the measurement data before and after grouting, including:

[0090] Plot the curves of acceleration and earth pressure changing with the distance from the explosion center, and compare and analyze the changing patterns of the values ​​at each measuring point before and after grouting; calculate the circumferential strain and axial strain of the buried pipeline measuring point AF before and after grouting, and plot the strain distribution curve; calculate the attenuation rate of various data before and after grouting; and comprehensively evaluate the protective effect of the grouting curtain: when the acceleration and earth pressure at the grouting curtain location show a significant decrease, and the overall attenuation rate of the buried pipeline strain reaches the expected value, it is determined that the grouting curtain has a good protective effect.

[0091] In this example, the control experiment was designed based on the following principles: 1. Scientific principles: A single variable control principle was used, changing only the variable of grouting; other experimental conditions (such as fill density and injection bag position) were kept completely consistent to ensure the comparability and reliability of the experimental data. 2. Operability principles: Two experiments were conducted in the same test chamber to reduce the impact of environmental factors; reserved grouting locations were provided for ease of construction; and a reasonable curing time was set to ensure full performance of the material properties.

[0092] In a specific example of the present invention, the specific implementation steps of the control experiment include:

[0093] Un-grouting state test (first blasting test): Ensure that the reserved grouting position 3 in the test box has not been grouting, check the working status of each measurement system, conduct the first blasting test and record the data: strain gauge 2 records pipeline strain data, accelerometer 4 records seismic wave propagation characteristics, and soil pressure cell 5 records soil stress changes.

[0094] Grouting construction: Use a grouting machine to perform grouting in the reserved position. Grouting parameter control: grouting pressure 0.7MPa, grouting area size 45×10×10cm, grouting material ratio of water-cement ratio 0.85, 800 mesh iron powder 15%, 100 mesh rubber 20%, curing time is 7 days to ensure that the grouting material is fully cured.

[0095] Grouting status test (second blasting test): After the curing period, a second blasting test is carried out, maintaining the same measurement point arrangement and parameter settings as the first test, and collecting the same type of experimental data.

[0096] The acceleration and soil pressure of the buried pipeline measurement points before and after grouting are statistically sorted and the data results are plotted into a graph, such as Figure 5 Analysis shows that acceleration and earth pressure increase as the distance from the blast center decreases, consistent with the attenuation law 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.

[0097] The strains of the buried pipeline measuring points before and after grouting are statistically sorted and the data results are plotted into a graph, as shown in the figure below. Figure 6 Observation Figure 6 It can be seen that the strains before and after the pipeline have significantly decreased, consistent with the acceleration and earth pressure mentioned above, with an attenuation of approximately 40%. Therefore, the grouting curtain material helps to attenuate the impact of blasting on buried pipelines, which is beneficial for protecting buried pipelines during blasting.

[0098] Based on the above, a rough criterion for judging the protective effect can be formed. That is, when the following conditions are met at the same time, it can be determined that the grouting curtain has a good protective effect: the acceleration and soil pressure at the grouting curtain location are significantly reduced, the overall strain attenuation rate of the buried pipeline reaches the expected value (about 40%), and the wave propagation characteristics at the grouting curtain location show obvious changes.

[0099] Through the setting and implementation of the above-mentioned control experiment, not only the protective effect of the grouting curtain was verified, but also its degree of protection was quantified, providing reliable technical support for engineering practice.

[0100] Based on the specific characteristics of urban buried pipeline blasting engineering sites, this study focused on shock-absorbing grouting materials, selected appropriate model test materials, designed model test procedures, and conducted model tests on the shock-absorbing performance of grouting curtains for controlling vibration during urban buried pipeline blasting. The results showed that the grouting curtains exhibited significant shock-absorbing properties, attenuating pipeline strain by approximately 40%, significantly attenuating seismic waves generated by blasting. This provided a certain degree of protection for buried pipelines and possessed practical engineering significance.

[0101] 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 testing a grouting curtain model system for underground pipeline vibration control, characterized in that: include: S1. Producing a test model based on similarity theory, including: determining a geometric similarity ratio, producing a model test box with a shock-absorbing boundary, and reserving a grouting position in the test box, the position being located between the explosive package and the buried pipeline; S2. Selecting model test materials, including: selecting fill materials appropriate to the project site, determining buried pipeline specifications, preparing explosive packs for simulated blasting, and preparing grouting curtain materials according to a predetermined ratio; S3. Arrange the measurement system and conduct tests, including: arranging strain measurement points on the pipeline surface, placing acceleration sensors and earth pressure sensors in the soil, and using a dynamic signal acquisition system to record measurement data during the simulated blasting process; The method for the grouting curtain model test system for underground pipeline vibration control also includes setting up a control experimental step: conducting a first blasting test and recording data in a non-grouting state, then injecting slurry into a reserved position to form a grouting curtain, and conducting a second blasting test and recording data after it solidifies, and evaluating the protective effect of the grouting curtain by comparing and analyzing the measurement data before and after grouting.

2. The method for testing a grouting curtain model system for underground pipeline vibration control according to claim 1, characterized in that: Silty clay is used as the filling material, PVC pipes are used for buried pipelines, and customized black powder is used as the explosive bag for simulated blasting. The vibration propagation law in the filling is verified through the deflagration test.

3. The method for testing a grouting curtain model system for underground pipeline vibration control according to claim 1, wherein: Step S1 includes: S11. Determine the geometric similarity ratio based on the first similarity theorem and the second similarity theory, and thereby determine the elastic modulus similarity ratio, bulk density similarity ratio, Poisson's ratio and friction angle similarity ratio, as well as the static and dynamic response similarity ratios. The first similarity theorem states that similar physical phenomena must obey the same objective laws, and the second similarity theorem states that physical phenomena of the same type must be similar when the single-valued conditions are similar and the similarity criteria composed of the physical quantities in the single-valued conditions are correspondingly equal. S12. Based on the characteristics of urban blasting projects, a 2×0.5×0.5m model test box was fabricated using steel and acrylic plates. Sponge was attached to the inner wall of the model test box as a shock-absorbing layer, and sponge pads were added around the perimeter and bottom of the model test box to absorb seismic waves generated by the blasting. S13. Prepare backfill soil according to the set mix ratio, fill it into the model test box to a height of 0.25m and level it.

4. The method for testing a grouting curtain model system for underground pipeline vibration control according to claim 1, wherein: In step S3, the arrangement of the measurement system includes: Strain measuring points are arranged on both sides of the buried pipeline, numbered AF, and each measuring point is equipped with circumferential and axial strain gauges; acceleration measuring points J1-J5 and soil pressure measuring points T1-T5 are arranged on the plane connecting the explosive bag and the buried pipeline; the strain gauges, acceleration sensors and soil pressure sensors are connected to the dynamic signal acquisition system through test lines.

5. The method for testing a grouting curtain model system for underground pipeline vibration control according to claim 4, characterized in that: The sampling frequency of the dynamic signal acquisition system is 10000 Hz, which is used to collect the strain data of buried pipelines, soil pressure and acceleration data in the soil.

6. The method for testing a grouting curtain model system for underground pipeline vibration control according to claim 4, wherein: The strain gauge is BF120-3BA with a measuring range of 20,000 με; the acceleration sensor is ICP / IEPE vibration acceleration sensor, and the soil pressure sensor is DMTY sensor.

7. The method for testing a grouting curtain model system for underground pipeline vibration control according to claim 1, wherein: The proportion of grouting curtain material is: water-cement ratio 0.85, 800 mesh iron powder content 15%, 100 mesh rubber content 20%.

8. The method for testing a grouting curtain model system for underground pipeline vibration control according to claim 1, wherein: In the control experiment steps, a grouting machine was used to inject slurry into the reserved position with a grouting pressure of 0.7 MPa to form a mixed grouting area; the second blasting test was carried out after the grouting material was allowed to fully solidify for 7 days.

9. The method for testing a grouting curtain model system for underground pipeline vibration control according to claim 4, wherein: The protective effect of the grouting curtain was evaluated by comparing and analyzing the measurement data before and after grouting, including: Plot the curves of acceleration and earth pressure changing with the distance from the explosion center, and compare and analyze the changing patterns of the values ​​at each measuring point before and after grouting; calculate the circumferential strain and axial strain of the buried pipeline measuring point AF before and after grouting, and plot the strain distribution curve; calculate the attenuation rate of various data before and after grouting; and comprehensively evaluate the protective effect of the grouting curtain: when the acceleration and earth pressure at the grouting curtain location show a significant decrease, and the overall attenuation rate of the buried pipeline strain reaches the expected value, it is determined that the grouting curtain has a good protective effect.

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