A sand-pebble stratum grouting diffusion simulation system and method

Abstract

The application discloses a sand-pebble stratum grouting diffusion simulation system and method, relates to the grouting simulation technical field, and comprises a test mold, a latex film is attached to the inner wall surface of the test mold, sand-pebble materials are filled in the test mold, and the bottom of the test mold is connected with a grout storage barrel through a grouting pipe; a plurality of resistance 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 resistance film pressure sensors collect pressure data in the slurry diffusion process in real time during the grouting process; the sand-pebble stratum environment of an actual engineering site is restored truly through the test mold and the flexible film, the pressure signals in the slurry diffusion process during the sand-pebble stratum grouting are collected in real time through the resistance film pressure sensors, the diffusion characteristics of the slurry at different times and the distribution characteristics of the grouting pressure at different positions in the stratum during the grouting process are obtained through data analysis, and a theoretical basis is provided for actual construction through data fitting.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of grouting simulation, in particular to a sand-pebble stratum grouting diffusion simulation system and method. BACKGROUND

[0002] In the sand-pebble stratum grouting reinforcement engineering, the diffusion range of the slurry and the distribution of the grouting pressure in the stratum directly affect the reinforcement effect on the stratum. The current research usually adopts indoor test, theoretical calculation and numerical simulation methods to determine the diffusion of the slurry with different performances in different types of strata. However, since the sand-pebble stratum belongs to a heterogeneous stratum, the diffusion path and pressure distribution of the slurry are relatively complex, and therefore the theoretical calculation and numerical simulation methods cannot accurately analyze the diffusion of the slurry in the stratum.

[0003] The indoor test method can reproduce the grouting process of the sand-pebble stratum through a large test mold and a grouting pump to study the grouting diffusion in the sand-pebble stratum. The existing indoor grouting test method and system mainly observe the slurry vein shape after grouting to analyze the diffusion shape of the slurry in the sand-pebble stratum by slicing the model, cannot capture the diffusion process in real time, and cannot obtain the grouting pressure changes at different stratum positions during the grouting process. Therefore, the existing grouting test method lacks effective real-time monitoring means, and it is difficult to obtain the diffusion process of the slurry in the stratum and the pressure distribution during the grouting process, and cannot provide a theoretical basis for the real sand-pebble stratum grouting reinforcement engineering. SUMMARY

[0004] In view of the problems existing in the prior art, the present application provides a sand-pebble stratum grouting diffusion simulation system and method, which restores the sand-pebble stratum environment of the actual engineering site through a test mold and a flexible film, adopts a small and sensitive resistance film pressure sensor to collect the pressure signals of the slurry diffusion process during the sand-pebble stratum grouting in real time, obtains the diffusion characteristics of the slurry at different times and the distribution characteristics of the grouting pressure at different positions in the stratum during the grouting process through data analysis, and provides a theoretical basis for the actual construction through data fitting.

[0005] The technical scheme of the present application is as follows:

[0006] In the first aspect of the present application, a sand-pebble stratum grouting diffusion simulation system is provided, which comprises a test mold, a latex film attached to the inner wall surface of the test mold, the test mold filled with sand-pebble materials, the bottom of the test mold connected to a slurry storage barrel through a grouting pipe, a grouting pump and a flowmeter arranged on the grouting pipe.

[0007] A plurality of resistance 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 plurality of resistance film pressure sensors are arranged in sequence and spaced apart in the vertical direction from top to bottom, and the resistance film pressure sensors collect pressure data in real time during the slurry diffusion process in the grouting process.

[0008] In some embodiments of the present application, the test mold is filled with sand and pebble materials according to the stratum conditions in the actual construction environment, so as to ensure that the stone content, pebble particle size distribution, water content of the sand layer, and clay content of the sand layer in the sand and pebble layer in the test mold are consistent with the actual construction environment.

[0009] In some embodiments of the present application, the test mold adopts a transparent acrylic cylinder, the latex film adopts a cylindrical shape and is 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.

[0010] In a second aspect of the present application, a sand and pebble stratum grouting diffusion simulation method is provided, comprising the following steps:

[0011] Grouting is performed in the test mold through the grouting pipe, and pressure data of the plurality of resistance film pressure sensors during the slurry diffusion process is collected in real time during the grouting process to obtain pressure-time data;

[0012] The pressure-time data of each resistance film pressure sensor is preprocessed, the slurry diffusion range-time data is obtained according to the preprocessed pressure-time data, the slurry diffusion range-time data of the plurality of resistance film pressure sensors is fitted, the relationship between the slurry diffusion range and the time is obtained, and the slurry diffusion range in the actual construction environment is predicted according to the grouting time in the actual construction environment.

[0013] According to the pressure data and the positions of the resistance film pressure sensors, the attenuation characteristics and pressure distribution of the grouting pressure at different positions in the stratum are obtained, and the grouting pressure at the predicted position in the actual construction environment is predicted according to the distance between the predicted position and the grouting port in the actual construction environment.

[0014] In some embodiments of the present application, when the pressure-time data is preprocessed, a low-pass filtering method is used to remove high-frequency noise in the sensor signal to smooth the data and avoid errors in subsequent analysis. The specific processing formula is as follows:

[0015] ;

[0016] Wherein, represents the pressure-time data after smoothing processing; represents the original pressure-time data; represents the grouting time; Smooth coefficient ， The value range is 0.1-0.3.

[0017] In some embodiments of the present application, the slurry diffusion range-time data is obtained according to the pre-processed pressure-time data, specifically including:

[0018] The threshold is set as 150% of the initial pressure of the resistance film pressure sensor P th When the pressure of a certain resistance film pressure sensor reaches the threshold, it means that the slurry has reached the position of the resistance film pressure sensor, and the time when the slurry diffuses to the position of the resistance film pressure sensor is recorded t n , and the coordinates of the position are recorded x n The slurry diffusion range-time data of the resistance film pressure sensor is obtained x n - t n .

[0019] In some embodiments of the present application, the diffusion range-time data obtained by the plurality of sensors is fitted x n - t n The relationship between the slurry diffusion range and time is established: x t

[0020] ;

[0021] Among them, x is the slurry diffusion range, i.e. the distance from the front end of the slurry to the grouting port, x 0 is the initial diffusion range, which is 0 here; a , b is a fitting parameter, which is obtained by fitting.

[0022] In some embodiments of the present application, the pressure decay characteristics and pressure distribution of the grouting pressure at different positions in the stratum are obtained according to the pressure data combined with the positions of the resistance film pressure sensors, specifically including:

[0023] When the slurry overflows from the top and the pressure data obtained by each resistance film pressure sensor is stable and unchanged, the pressure of each resistance film pressure sensor at this time is recorded P fn as the stable grouting pressure at its position, and the grouting pressure decay degree at the position is obtained by the following formula:

[0024] ;​​

[0025] wherein, D n is x n a pressure decay factor at the position, P 0 is the grouting pressure of the grouting pump, P fn is x n a stable grouting pressure at the position;

[0026] further obtain the decay degree data of the grout at different positions in the sandy pebble stratum D n- x n .

[0027] In some embodiments of the present application, a nonlinear regression method is adopted to obtain the grouting pressure P the decay degree at different positions in the sandy pebble stratum D and the grouting pressure at different positions :

[0028] ;

[0029] ;

[0030] wherein, c, d is a fitting coefficient, obtained by fitting, l is the distance between the stratum position and the grouting port.

[0031] In some embodiments of the present application, the pressure data is collected by a plurality of resistance film pressure sensors, each resistance film sensor is powered separately, and the voltage is set to a constant value V , the pressure received by each resistance film pressure sensor is calculated by the current I i , the sensitivity coefficient k, and the effective surface area A

[0032] ;

[0033] wherein, P n is the local pressure measured by the nth sensor; I n is the current value measured by the nth sensor; k n is the sensitivity coefficient of the nth sensor; A is the effective area of the sensor. ​

[0034] The one or more technical solutions of the present application have the following beneficial effects:

[0035] (1) The sand-pebble stratum grouting diffusion simulation system provided by the present application, through the combination of the test mold and the latex film, not only constructs a real sand-pebble stratum simulation grouting experimental stratum environment, but also provides space and protection for the arrangement of the sensor, avoids the influence of water and pebbles on the sensor, and ensures the reception of pressure data; through the plurality of evenly distributed resistance film pressure sensors, the pressure changes in the sand-pebble stratum grout diffusion process at different times and different positions are obtained, and real-time monitoring of the grout diffusion is realized.

[0036] (2) The sand-pebble stratum grouting diffusion simulation method provided by the present application, through data preprocessing and analysis method, based on pressure data, the diffusion range of grout in sand-pebble stratum changes with grouting time and the grouting pressure decay at different positions in sand-pebble stratum are obtained; the fitting formula established by the obtained data can predict the grout diffusion range and grouting pressure according to the grouting time and stratum position in the actual construction process, and provide a theoretical basis for the grouting reinforcement construction in the real sand-pebble stratum. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 is a structural schematic view of the sand-pebble stratum grouting diffusion simulation system of the present application;

[0038] Figure 2 is a flow chart of the sand-pebble stratum grouting simulation platform for grouting test.

[0039] In the figure: 1, data acquisition and analysis unit; 2, data transmission line; 3, resistance film pressure sensor; 4, sand-pebble; 5, grouting pipe; 6, grout storage barrel; 7, grouting pump; 8, transparent acrylic cylinder; 9, latex film. DETAILED DESCRIPTION

[0040] The present application will be further described below in combination with the drawings and examples.

[0041] Example 1

[0042] In a typical embodiment of the present application, a sand-pebble stratum grouting diffusion simulation system is provided, which comprises a test mold, a latex film is attached to the inner wall surface of the test mold, the test mold is filled with sand-pebble material, the bottom of the test mold is connected with a grout storage barrel through a grouting pipe, and a grouting pump and a flowmeter are arranged on the grouting pipe;

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] In the grouting test, the end of the latex film bonded with the test mold is the grouting end, the flange plate is connected with the grouting pipe 5, the grouting pump 7 (the pressure range is 0-10 MPa, and the accuracy is ±0.5% FS) and the grouting barrel 6 to inject the cement slurry with a water-cement ratio of 1:1 at a constant pressure P.

[0048] The embodiment combines the test mold and the latex film, not only constructs a real sand pebble stratum simulation grouting experimental stratum environment, but also provides space and protection for the arrangement of the sensor, avoids the influence of water and pebbles on the sensor, ensures the reception of pressure data, obtains the pressure change in the sand pebble stratum slurry diffusion process at different times and different positions through multiple evenly distributed resistance film pressure sensors, and realizes real-time monitoring of the slurry diffusion.

[0049] Embodiment 2

[0050] In a typical embodiment of the present application, a sand pebble stratum grouting diffusion simulation method is provided, as shown in the figure, comprising the following steps: Figure 2

[0051] Step one, grouting is performed in the test mold through the grouting pipe, and the pressure data of multiple resistance film pressure sensors in the slurry diffusion process is collected in real time during the grouting process to obtain pressure-time data;

[0052] Step two, the pressure-time data of each resistance film pressure sensor is preprocessed, the slurry diffusion range-time data is obtained according to the preprocessed pressure-time data, the slurry diffusion range-time data of multiple resistance film pressure sensors is fitted, the relationship between the slurry diffusion range and the time is obtained, and the slurry diffusion range in the actual construction environment is predicted according to the grouting time in the actual construction environment;

[0053] Step three, the attenuation characteristics and pressure distribution of the grouting pressure at different positions in the stratum are obtained according to the pressure data and the positions of the resistance film pressure sensors, and the grouting pressure at the predicted position in the actual construction environment is predicted according to the distance between the predicted position and the grouting port in the actual construction environment.

[0054] The specific process is as follows:

[0055] Step one, grouting is performed in the test mold through the grouting pipe, and the pressure data of multiple resistance film pressure sensors in the slurry diffusion process is collected in real time during the grouting process to obtain pressure-time data:

[0056] The pressure data is collected by multiple resistance film pressure sensors, each resistance film sensor is powered separately, and the voltage is set to a constant value V The current of each resistance film pressure sensor is I ​i , sensitivity coefficient k, effective surface area A Calculate the pressure on each resistive film pressure sensor:

[0057] ;

[0058] wherein, P n is the local pressure measured by the nth sensor; I n is the current value measured by the nth sensor; k n is the sensitivity coefficient of the nth sensor; A is the effective area of the sensor.

[0059] The pressure value on each sensor is continuously monitored from the start of grouting, and the change of the pressure value on each sensor with time, i.e. the pressure-time (P-t) data curve, is obtained. P n - t

[0060] Step two, pre-process the pressure-time data of each resistive film pressure sensor, obtain the slurry diffusion range-time data from the pre-processed pressure-time data, fit the slurry diffusion range-time data of multiple resistive film pressure sensors, obtain the relationship between the slurry diffusion range and time, and predict the slurry diffusion range in the actual construction environment according to the grouting time in the actual construction environment.

[0061] Specifically, when pre-processing the pressure-time data, a low-pass filtering method is used to remove high-frequency noise in the sensor signal to smooth the data and avoid errors in subsequent analysis. The specific processing formula is as follows:

[0062] ;

[0063] wherein, represents the pressure-time data after smoothing processing; represents the original pressure-time data; represents the grouting time; represents the smoothing coefficient ， The value range is 0.1-0.3.

[0064] Further, the slurry diffusion range-time data is obtained according to the pre-processed pressure-time data, which specifically includes:

[0065] According to the results of previous experiments, set 150% of the initial pressure of the resistive film pressure sensor as the threshold P th ​When the pressure of a certain resistance film pressure sensor reaches the threshold value, it represents that the slurry has reached the position of the resistance film pressure sensor, and the time when the slurry spreads to the position of the resistance film pressure sensor is recorded t n , and the coordinates of the position are recorded x n , the slurry spreading range-time data of the resistance film pressure sensor is obtained x n - t n .

[0066] Further, the diffusion range-time data obtained by the plurality of sensors is fitted to establish the relationship between the slurry diffusion range and the time: x n - t n x t

[0067] ;

[0068] wherein, x is the slurry diffusion range, i.e. the distance from the front end of the slurry to the grouting port, x 0 is the initial diffusion range, which is 0 here; a , b is a fitting parameter, which is obtained by fitting.

[0069] Step three, according to the pressure data combined with the position of the resistance film pressure sensor, the attenuation characteristics and pressure distribution of the grouting pressure at different positions in the stratum are obtained, and the grouting pressure at the predicted position in the actual construction environment is predicted according to the distance between the predicted position and the grouting port in the actual construction environment.

[0070] Specifically includes:

[0071] When the slurry overflows from the top and the pressure data obtained by each resistance film pressure sensor is stable and unchanged, the pressure of each resistance film pressure sensor at this time is recorded P fn as the stable grouting pressure at its position, and the grouting pressure attenuation degree at the position is obtained by the following formula:

[0072] ;

[0073] wherein, D n is the x n pressure attenuation factor at the position, P 0 is the grouting pressure of the grouting pump, P ​​​fn for x n Stable grouting pressure at the location;

[0074] 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 .

[0075] 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 :

[0076] ;

[0077] ;

[0078] in, c, d These are the fitting coefficients, obtained through fitting. l This is the distance between the stratum and the grouting port.

[0079] 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.

[0080] 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 method for simulating grouting diffusion in sandy and gravelly formations, 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. A latex film is attached to the inner wall of the test mold, and multiple resistive thin-film pressure sensors are set 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 pressure-time data from each resistive thin-film pressure sensor is preprocessed to obtain grout diffusion range-time data. The grout diffusion range-time data from multiple resistive thin-film pressure sensors are then fitted to determine the relationship between grout diffusion range and time. Based on the grouting time in the actual construction environment, the grout diffusion range in the actual construction environment is predicted. Specifically, the 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. 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. The grouting pressure at the predicted location in the actual construction environment is predicted based on the distance between the predicted location and the grouting port. 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 refers to the distance between the geological formation and the grouting port. P 0 represents the grouting pressure of the grouting pump.

2. The grouting diffusion simulation method for sand and gravel strata as described in claim 1, 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.

3. The grouting diffusion simulation method for sand and gravel formations as described in claim 1, 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 .

4. The grouting diffusion simulation method for sand and gravel formations as described in claim 1, 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 .

5. The grouting diffusion simulation method for sand and gravel formations as described in claim 1, 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 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.

6. A grouting diffusion simulation system for sand and gravel formations, used to implement the grouting diffusion simulation method for sand and gravel formations as described in any one of claims 1-5, 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.

7. The grouting diffusion simulation system for sand and gravel formations as described in claim 6, 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.

8. The grouting diffusion simulation system for sand and gravel formations as described in claim 6, 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.

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