Sandy gravel stratum grouting diffusion simulation system and method

Abstract

The invention discloses a sandy gravel stratum grouting diffusion simulation system and method, and relates to the technical field of grouting simulation, the system comprises a test mold, a latex film is attached to the inner wall surface of the test mold, the test mold is filled with a sandy gravel material, and the bottom of the test mold is connected with a slurry storage barrel through a grouting pipe; a plurality of resistive film pressure sensors are arranged between the inner wall surface of the test mold and the outer wall surface of the latex film, and the resistive film pressure sensors collect pressure data in the slurry diffusion process in real time in the grouting process; the sandy gravel stratum environment of an actual engineering site is truly restored through the test mold and the flexible film, and the resistive film pressure sensor is used for collecting pressure signals in the slurry diffusion process in real time when the sandy gravel stratum is grouted; diffusion characteristics of grout at different time in the grouting process and distribution characteristics of grouting pressure at different positions in a stratum are obtained through data analysis, and a theoretical basis is provided for actual construction through data fitting.

Description

Technical Field

[0001] This invention relates to the field of grouting simulation technology, specifically to a grouting diffusion simulation system and method for sand and gravel formations. Background Technology

[0002] In grouting reinforcement projects for sandy and gravelly formations, the diffusion range of the grout and the distribution of grouting pressure directly affect the reinforcement effect. Current research typically employs methods such as laboratory tests, theoretical calculations, and numerical simulations to determine the diffusion of grouts with different properties in different types of formations. However, because sandy and gravelly formations are heterogeneous, the diffusion path and pressure distribution of the grout are complex. Therefore, theoretical calculations and numerical simulations cannot accurately analyze the diffusion of grout in this formation.

[0003] Indoor testing methods can realistically replicate the grouting process in gravel strata using large-scale test molds and grouting pumps, enabling research on grout diffusion in these strata. Existing indoor grouting test methods and systems primarily rely on observing grout vein morphology by dissecting the model after grouting to analyze grout diffusion patterns in gravel strata. However, these methods cannot capture the diffusion process in real time or obtain grout pressure changes at different stratum locations during the grouting process. Therefore, existing grouting test methods lack effective real-time monitoring capabilities, making it difficult to obtain the grout diffusion process and pressure distribution within the stratum during grouting, and thus failing to provide a theoretical basis for real-world grouting reinforcement projects in gravel strata. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides a grouting diffusion simulation system and method for sand and gravel strata. The system realistically recreates the sand and gravel strata environment of an actual engineering site using experimental molds and flexible membranes. A compact and highly responsive resistive thin-film pressure sensor is employed to collect pressure signals during the grout diffusion process in real time. Data analysis reveals the diffusion characteristics of the grout at different times during the grouting process and the distribution characteristics of the grouting pressure at different locations within the strata. Data fitting provides a theoretical basis for actual construction.

[0005] The technical solution of the present invention is as follows: In a first aspect of the present invention, a grouting diffusion simulation system for sand and gravel formations is provided, comprising a test mold, wherein a latex film is attached to the inner wall surface of the test mold, the test mold is filled with sand and gravel material, the bottom of the test mold is connected to a grout storage tank through a grouting pipe, and a grouting pump and a flow meter are provided on the grouting pipe; Multiple resistive thin-film pressure sensors are installed between the inner wall of the test mold and the outer wall of the latex film. The multiple resistive thin-film pressure sensors are arranged at intervals from top to bottom in the vertical direction. The resistive thin-film pressure sensors collect pressure data in real time during the grout diffusion process.

[0006] In some embodiments of the present invention, the test mold is filled with sand and gravel material according to the geological conditions in the actual construction environment, so as to ensure that the stone content, gravel particle size distribution, sand moisture content and sand clay content in the sand and gravel layer in the test mold are consistent with the actual construction environment. In some embodiments of the present invention, the test mold is a transparent acrylic cylinder, the latex film is cylindrical and coaxially arranged with the transparent acrylic cylinder, and the inner wall surface of the transparent acrylic cylinder is in close contact with the outer wall surface of the latex film.

[0007] In a second aspect of the present invention, a method for simulating grouting diffusion in sandy and gravelly formations is provided, comprising the following steps: Grout is injected into the test mold through a grouting pipe. During the grouting process, pressure data from multiple resistive thin-film pressure sensors are collected in real time during the grout diffusion process to obtain pressure-time data. The pressure-time data of each resistive thin-film pressure sensor is preprocessed, and the slurry diffusion range-time data is obtained based on the preprocessed pressure-time data. The slurry diffusion range-time data of multiple resistive thin-film pressure sensors are fitted to obtain the relationship between slurry diffusion range and time. Based on the grouting time in the actual construction environment, the slurry diffusion range in the actual construction environment is predicted. Based on the pressure data and the location of the resistive thin-film pressure sensor, the attenuation characteristics and pressure distribution of the grouting pressure at different locations in the formation are obtained. Based on the distance between the predicted location and the grouting port in the actual construction environment, the grouting pressure at the predicted location in the actual construction environment is predicted.

[0008] In some embodiments of the present invention, when preprocessing pressure-time data, a low-pass filtering method is used to remove high-frequency noise from the sensor signal to smooth the data and avoid errors in subsequent analysis. The specific processing formula is as follows: ; in, This represents the pressure-time data after smoothing. This represents the raw pressure-time data; Indicates the grouting time; Represents the smoothing coefficient ， The value range is 0.1-0.3. In some embodiments of the present invention, obtaining slurry diffusion range-time data based on pretreated pressure-time data specifically includes: Set the threshold to 150% of the initial pressure of the resistive diaphragm pressure sensor. P thWhen the pressure of a certain resistive thin-film pressure sensor reaches the threshold, it means that the slurry has reached the location of that resistive thin-film pressure sensor. The time it takes for the slurry to diffuse to the location of the resistive thin-film pressure sensor is recorded. t n And record the coordinates of that location. x n Obtain the slurry diffusion range-time data of the resistive thin-film pressure sensor. x n - t n . In some embodiments of the present invention, diffusion range-time data acquired by multiple sensors are used. x n - t n Fitting was performed to establish the slurry diffusion range. x With time t The relationship between them: ; in, x This refers to the grout diffusion range, which is the distance from the front end of the grout to the injection port. x 0 represents the initial diffusion range, which is 0 in this case; a , b These are the fitting parameters, obtained through fitting.

[0009] In some embodiments of the present invention, based on pressure data and the location of the resistive thin-film pressure sensor, the attenuation characteristics and pressure distribution of the grouting pressure at different locations in the formation are obtained, specifically including: Once the slurry overflows from the top and the pressure data acquired by each resistive thin-film pressure sensor remains stable, record the pressure of each resistive thin-film pressure sensor at this point. P fn The stable grouting pressure at its location is used as the grouting pressure at that location, and the degree of grouting pressure attenuation at that location is obtained by the following formula: ; in, D n for x n Pressure attenuation factor at location, P 0 represents the grouting pressure of the grouting pump. P fn for x n Stable grouting pressure at the location; This allows us to obtain data on the attenuation of the slurry at different locations within the sand and gravel strata. D n- xn .

[0010] In some embodiments of the present invention, a nonlinear regression method is used to obtain the grouting pressure. P Attenuation at different locations in the gravel strata D and grouting pressure at different locations : ; ; in, c, d These are the fitting coefficients, obtained through fitting. l This is the distance between the stratum and the grouting port.

[0011] In some embodiments of the present invention, the pressure data is acquired through multiple resistive thin-film pressure sensors, each of which is individually powered with a constant voltage. V The current passing through each resistive thin-film pressure sensor I i Sensitivity coefficient k, effective surface area A Calculate the pressure experienced by each resistive thin-film pressure sensor: ; in, P n The local pressure measured by the nth sensor; I n The value of the current measured by the nth sensor; k n Let n be the sensitivity coefficient of the nth sensor; A This represents the effective area of ​​the sensor.

[0012] One or more technical solutions of the present invention have the following beneficial effects: (1) The sand and gravel stratum grouting diffusion simulation system provided by the present invention not only constructs a real sand and gravel stratum grouting experimental stratum environment by combining test molds and latex membranes, but also provides space and protection for the arrangement of sensors. While avoiding the influence of moisture and pebbles on the sensors, it ensures the reception of pressure data. Through multiple uniformly distributed resistive thin film pressure sensors, the pressure changes during the diffusion process of grout in sand and gravel stratum at different times and locations are obtained, realizing real-time monitoring of grout diffusion.

[0013] (2) The grouting diffusion simulation method for sand and gravel strata provided by the present invention obtains the change of grout diffusion range in sand and gravel strata with grouting time and the attenuation of grouting pressure at different locations in sand and gravel strata based on pressure data through data preprocessing and analysis methods; the fitting formula established by the obtained data can predict the grout diffusion range and grouting pressure according to the grouting time and stratum location in the actual construction process, and provide a theoretical basis for grouting reinforcement construction in real sand and gravel strata. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the grouting diffusion simulation system for sand and gravel formations of the present invention; Figure 2 This is a flowchart of a grouting test conducted using the sand and gravel formation grouting simulation platform of the present invention.

[0015] In the diagram: 1. Data acquisition and analysis unit; 2. Data transmission line; 3. Resistive thin-film pressure sensor; 4. Sand and gravel; 5. Grouting pipe; 6. Grout storage tank; 7. Grouting pump; 8. Transparent acrylic cylinder; 9. Latex film. Detailed Implementation

[0016] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0017] Example 1 In a typical embodiment of the present invention, a grouting diffusion simulation system for sand and gravel formations is proposed, including a test mold, with a latex film attached to the inner wall of the test mold, the test mold filled with sand and gravel material, and the bottom of the test mold connected to a grout storage tank through a grouting pipe, with a grouting pump and a flow meter installed on the grouting pipe; Multiple resistive thin-film pressure sensors are installed between the inner wall of the test mold and the outer wall of the latex film. The multiple resistive thin-film pressure sensors are arranged at intervals from top to bottom in the vertical direction. The resistive thin-film pressure sensors collect pressure data in real time during the grout diffusion process.

[0018] When constructing the grouting simulation platform for gravel strata, the test mold is filled with gravel material according to the geological conditions of the actual construction environment. This ensures that parameters such as the stone content, gravel particle size distribution, sand moisture content, and clay content in the gravel layer within the test mold are consistent with the actual construction environment. When filling the test mold with gravel, the gravel material is placed in layers into the latex film within the mold. After each set height, a vibratory compactor is used to compact the material until the latex film adheres tightly to the inner wall of the acrylic cylinder, until the test mold is completely filled with gravel material.

[0019] In this embodiment, the test mold is a transparent acrylic cylinder, the latex film is cylindrical and coaxially arranged with the transparent acrylic cylinder, and the inner wall of the transparent acrylic cylinder is in close contact with the outer wall of the latex film.

[0020] In one specific embodiment of this example, the following is adopted: Figure 1 The sand and gravel stratum grouting simulation platform shown uses a transparent acrylic cylinder 8 with an inner diameter of 60cm, a thickness of 3cm, and a height of 100cm as the test mold. A cylindrical latex film 9 with an outer diameter of 60cm, a thickness of 0.2cm, and a length of 100cm is placed coaxially inside the test mold. When the latex film 9 is fully unfolded, it can adhere tightly to the inner wall of the test mold. One end of the latex membrane 9 is bonded to one end of the test mold using waterproof adhesive. From the other end, the resistive film pressure sensor 3 is placed in the annular gap between the latex membrane 9 and the test mold, and then fixed to the inner wall of the test mold using waterproof adhesive. Starting from the end of the test mold fixed to the latex membrane, one resistive film pressure sensor is placed every 5 cm along the axial direction (a total of 20 sensors). The resistive film pressure sensors are arranged vertically, numbered S1, S2, ..., S20 along the axial direction of the grouting test mold, starting from the grouting end. With the grouting port as the zero point, the position of each sensor is x1=2.5cm, x2=7.5cm, ..., x20. 20 =97.5cm. The data transmission line 2 of the resistive thin-film pressure sensor is led out from the end of the latex membrane 9 that is not bonded to the test mold and connected to the data acquisition and analysis unit 1. The sand and gravel material 4 is placed in layers into the latex membrane in the test mold, and compacted every 20cm using a vibratory compactor (frequency 30Hz, excitation force 5kN) until the latex membrane is tightly attached to the inner wall of the acrylic cylinder, until the sand and gravel material fills the test mold.

[0021] During the grouting test, the end of the latex film bonded to the test mold is used as the grouting end. The grouting pipe 5, the grouting pump 7 (pressure range 0-10MPa, accuracy ±0.5%FS) and the grout storage tank 6 are connected through the flange. Cement grout with a water-cement ratio of 1:1 is injected at a constant pressure P.

[0022] This embodiment, by combining a test mold and a latex membrane, not only constructs a realistic sand and gravel stratum to simulate the grouting test environment, but also provides space and protection for the sensor arrangement. While avoiding the sensor from being affected by moisture and pebbles, it ensures the reception of pressure data. Through multiple uniformly distributed resistive thin-film pressure sensors, the pressure changes during the grout diffusion process in the sand and gravel stratum at different times and locations are obtained, realizing real-time monitoring of grout diffusion.

[0023] Example 2 In a typical embodiment of the present invention, a method for simulating grouting diffusion in sandy and gravelly formations is provided, such as... Figure 2 As shown, it includes the following steps: Step 1: Grout is injected into the test mold through the grouting pipe. During the grouting process, pressure data from multiple resistive thin-film pressure sensors are collected in real time during the grout diffusion process to obtain pressure-time data. Step 2: Preprocess the pressure-time data of each resistive thin-film pressure sensor, obtain slurry diffusion range-time data based on the preprocessed pressure-time data, fit the slurry diffusion range-time data of multiple resistive thin-film pressure sensors to obtain the relationship between slurry diffusion range and time, and predict the slurry diffusion range in the actual construction environment based on the grouting time in the actual construction environment. Step 3: Based on the pressure data and the location of the resistive thin-film pressure sensor, obtain the attenuation characteristics and pressure distribution of the grouting pressure at different locations in the formation. Based on the distance between the predicted location and the grouting port in the actual construction environment, predict the grouting pressure at the predicted location in the actual construction environment.

[0024] The specific process is as follows: Step 1: Grout is injected into the test mold through the grouting pipe. During the grouting process, pressure data from multiple resistive thin-film pressure sensors is collected in real time during the grout diffusion process to obtain pressure-time data. The pressure data is acquired through multiple resistive thin-film pressure sensors, each of which is individually powered with a constant voltage. V The current passing through each resistive thin-film pressure sensor I i Sensitivity coefficient k, effective surface area A Calculate the pressure experienced by each resistive thin-film pressure sensor: ; in, P n The local pressure measured by the nth sensor; I n The current value measured by the nth sensor; k n Let n be the sensitivity coefficient of the nth sensor; A The effective area of ​​the sensor.

[0025] By continuously monitoring the pressure value on each sensor from the start of grouting, the change in pressure value on each sensor over time can be obtained, i.e., pressure-time (PST). P n - t Data curve.

[0026] Step 2: Preprocess the pressure-time data of each resistive thin-film pressure sensor, obtain slurry diffusion range-time data based on the preprocessed pressure-time data, fit the slurry diffusion range-time data of multiple resistive thin-film pressure sensors to obtain the relationship between slurry diffusion range and time, and predict the slurry diffusion range in the actual construction environment based on the grouting time in the actual construction environment.

[0027] Specifically, when preprocessing pressure-time data, a low-pass filter is used to remove high-frequency noise from the sensor signal to smooth the data and avoid errors in subsequent analysis. The specific processing formula is as follows: ; in, This represents the pressure-time data after smoothing. This represents the raw pressure-time data; Indicates the grouting time; Represents the smoothing coefficient ， The value range is 0.1-0.3.

[0028] Furthermore, based on the pretreated pressure-time data, the slurry diffusion range-time data are obtained, specifically including: Based on previous experimental results, 150% of the initial pressure of the resistive thin-film pressure sensor was set as the threshold. P th When the pressure of a certain resistive thin-film pressure sensor reaches the threshold, it means that the slurry has reached the location of that resistive thin-film pressure sensor. The time it takes for the slurry to diffuse to the location of the resistive thin-film pressure sensor is recorded. t n And record the coordinates of that location. x n Obtain the slurry diffusion range-time data of the resistive thin-film pressure sensor. x n - t n .

[0029] Furthermore, the diffusion range-time data acquired by multiple sensors... x n - t n Fitting was performed to establish the slurry diffusion range. x With time t The relationship between them: ; in, x This refers to the grout diffusion range, which is the distance from the front end of the grout to the injection port. x 0 represents the initial diffusion range, which is 0 in this case;a , b These are the fitting parameters, obtained through fitting.

[0030] Step 3: Based on the pressure data and the location of the resistive thin-film pressure sensor, obtain the attenuation characteristics and pressure distribution of the grouting pressure at different locations in the formation. Based on the distance between the predicted location and the grouting port in the actual construction environment, predict the grouting pressure at the predicted location in the actual construction environment.

[0031] Specifically, it includes: Once the slurry overflows from the top and the pressure data acquired by each resistive thin-film pressure sensor remains stable, record the pressure of each resistive thin-film pressure sensor at this point. P fn The stable grouting pressure at its location is used as the grouting pressure at that location, and the degree of grouting pressure attenuation at that location is obtained by the following formula: ; in, D n for x n Pressure attenuation factor at location, P 0 represents the grouting pressure of the grouting pump. P fn for x n Stable grouting pressure at the location; This allows us to obtain data on the attenuation of the slurry at different locations within the sand and gravel strata. D n- x n .

[0032] Furthermore, by employing a nonlinear regression method, the grouting pressure can be obtained. P Attenuation at different locations in the gravel strata D and grouting pressure at different locations : ; ; in, c, d These are the fitting coefficients, obtained through fitting. l This is the distance between the stratum and the grouting port.

[0033] This embodiment uses data preprocessing and analysis methods to obtain the variation of grout diffusion range in sand and gravel strata with grouting time and the attenuation of grouting pressure at different locations in sand and gravel strata based on pressure data. The fitting formula established by the obtained data provides a theoretical basis for predicting grout diffusion range and grouting pressure based on grouting time and stratum location, and for grouting reinforcement construction in real sand and gravel strata.

[0034] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A grouting diffusion simulation system for sand and gravel formations, characterized in that, The test mold includes a latex film attached to the inner wall of the test mold, and the test mold is filled with sand and gravel material. The bottom of the test mold is connected to the grout storage tank through a grouting pipe, and a grouting pump and a flow meter are installed on the grouting pipe. Multiple resistive thin-film pressure sensors are installed between the inner wall of the test mold and the outer wall of the latex film. The multiple resistive thin-film pressure sensors are arranged at intervals from top to bottom in the vertical direction. The resistive thin-film pressure sensors collect pressure data in real time during the grout diffusion process.

2. The grouting diffusion simulation system for sand and gravel formations as described in claim 1, characterized in that, The test mold is filled with sand and gravel material according to the geological conditions in the actual construction environment, so as to ensure that the stone content, gravel particle size distribution, sand moisture content and sand clay content in the sand and gravel layer in the test mold are consistent with the actual construction environment.

3. The grouting diffusion simulation system for sand and gravel formations as described in claim 1, characterized in that, The test mold is a transparent acrylic cylinder, and the latex film is cylindrical and coaxially arranged with the transparent acrylic cylinder. The inner wall of the transparent acrylic cylinder is in close contact with the outer wall of the latex film.

4. A method for simulating grouting diffusion in sandy and gravelly formations, implemented using the simulation system described in any one of claims 1-3, characterized in that, Includes the following steps: Grout is injected into the test mold through a grouting pipe. During the grouting process, pressure data from multiple resistive thin-film pressure sensors are collected in real time during the grout diffusion process to obtain pressure-time data. The pressure-time data of each resistive thin-film pressure sensor is preprocessed, and the slurry diffusion range-time data is obtained based on the preprocessed pressure-time data. The slurry diffusion range-time data of multiple resistive thin-film pressure sensors are fitted to obtain the relationship between slurry diffusion range and time. Based on the grouting time in the actual construction environment, the slurry diffusion range in the actual construction environment is predicted. Based on the pressure data and the location of the resistive thin-film pressure sensor, the attenuation characteristics and pressure distribution of the grouting pressure at different locations in the formation are obtained. Based on the distance between the predicted location and the grouting port in the actual construction environment, the grouting pressure at the predicted location in the actual construction environment is predicted.

5. The grouting diffusion simulation method for sand and gravel formations as described in claim 4, characterized in that, When preprocessing pressure-time data, a low-pass filter is used to remove high-frequency noise from the sensor signal to smooth the data and avoid errors in subsequent analysis. The specific processing formula is as follows: ； in, This represents the pressure-time data after smoothing. This represents the raw pressure-time data; Indicates the grouting time; Represents the smoothing coefficient ， The value range is 0.1-0.

3.

6. The grouting diffusion simulation method for sand and gravel formations as described in claim 4, characterized in that, Based on the pretreated pressure-time data, the slurry diffusion range-time data were obtained, specifically including: Set the threshold to 150% of the initial pressure of the resistive diaphragm pressure sensor. P th When the pressure of a certain resistive thin-film pressure sensor reaches the threshold, it means that the slurry has reached the location of that resistive thin-film pressure sensor. The time it takes for the slurry to diffuse to the location of the resistive thin-film pressure sensor is recorded. t n And record the coordinates of that location. x n Obtain the slurry diffusion range-time data of the resistive thin-film pressure sensor. x n - t n .

7. The grouting diffusion simulation method for sand and gravel formations as described in claim 6, characterized in that, Diffusion range-time data acquired from multiple sensors x n - t n Fitting was performed to establish the slurry diffusion range. x With time t The relationship between them: ； in, x This refers to the grout diffusion range, which is the distance from the front end of the grout to the injection port. x 0 represents the initial diffusion range, which is 0 in this case; a , b These are the fitting parameters, obtained through fitting.

8. The grouting diffusion simulation method for sand and gravel formations as described in claim 4, characterized in that, Based on pressure data and the location of the resistive thin-film pressure sensor, the attenuation characteristics and pressure distribution of grouting pressure at different locations in the formation are obtained, specifically including: Once the slurry overflows from the top and the pressure data acquired by each resistive thin-film pressure sensor remains stable, record the pressure of each resistive thin-film pressure sensor at this point. P fn The stable grouting pressure at its location is used as the grouting pressure at that location, and the degree of grouting pressure attenuation at that location is obtained by the following formula: ； in, D n for x n Pressure attenuation factor at location, P 0 represents the grouting pressure of the grouting pump. P fn for x n Stable grouting pressure at the location; This allows us to obtain data on the attenuation of the slurry at different locations within the sand and gravel strata. D n- x n .

9. The grouting diffusion simulation method for sand and gravel formations as described in claim 8, characterized in that, The grouting pressure can be obtained by using a nonlinear regression method. P Attenuation at different locations in the gravel strata D and grouting pressure at different locations : ； ； in, c, d These are the fitting coefficients, obtained through fitting. l This is the distance between the stratum and the grouting port.

10. The grouting diffusion simulation method for sand and gravel formations as described in claim 4, characterized in that, The pressure data is acquired through multiple resistive thin-film pressure sensors, each of which is individually powered with a constant voltage. V The current passing through each resistive thin-film pressure sensor I i Sensitivity coefficient k, effective surface area A Calculate the pressure experienced by each resistive thin-film pressure sensor: ； in, P n The local pressure measured by the nth sensor; I n The current value measured by the nth sensor; k n Let n be the sensitivity coefficient of the nth sensor; A The effective area of ​​the sensor.

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