Transparent sand EICP grouting test device considering pore solution seepage and test method thereof

Abstract

The invention provides a transparent sand EICP grouting test device considering pore solution seepage and a test method thereof. The device comprises a grouting diffusion device and a laser imaging device. According to the device, a multicolor laser irradiation technology is adopted, and grouting liquid, pore water and sand particles have differentiated color development characteristics in a transparent model box through the synergistic effect of specific-wavelength laser, solution fluorescence labeling and fluorescent pigment on the surface of sandy soil. PIV and PTV technologies are adopted to observe the change of slurry flow diffusion and slurry flow velocity, and PLIF technology is adopted to observe the precipitation process of calcium carbonate in soil particle pores. On the basis of test data, pore structure changes can be analyzed, the calcium carbonate precipitation amount can be quantified, the spatial and temporal distribution rule of calcium carbonate precipitation and the particle release rule under the hydraulic action are disclosed, a theoretical basis is provided for optimizing the shield tunnel biological grouting technology, and a new thought is provided for preventing and treating water leakage of a water-rich sand layer shield tunnel.

Description

Technical Field

[0001] The invention relates to the technical field of geotechnical engineering, and in particular to a transparent sand EICP grouting test device and a test method thereof taking pore solution seepage into consideration. Background Art

[0002] The complex and ever-changing environment of shield tunnels makes it difficult to guarantee the conditions and quality of waterproofing work, making water leakage a prominent issue during operation. Leakage can cause localized water and sand surges in the tunnel, leading to pavement cracks or sudden ground collapses. This can lead to traffic closures on surrounding roads, ruptures in underground pipelines, and power and water outages for residents, resulting in incalculable consequences and losses.

[0003] The soil solidification method based on urease-induced calcium carbonate precipitation is a new solidification technology. Its basic principle is to use a calcium ion source to induce the production of a large amount of calcium carbonate precipitation, thereby improving the pore structure of the soil and increasing the strength and erosion resistance of the soil. It has significant advantages such as low cost, high solidification efficiency, and environmental friendliness. The core of the transparent soil test technology is to prepare artificial synthetic transparent materials with similar engineering properties to natural soil. By making the aggregate and pore fluid have similar refractive indices, the prepared soil is kept transparent, thereby providing technical support for the visualization of particle migration in porous media, which has significant advantages. However, the application of this technology in the field of EICP solidification of sand is still rare, and the diffusion-reaction mechanism of EICP grouting is not yet clearly understood, making it difficult to form a standardized test device. Summary of the Invention

[0004] The purpose of the present invention is to provide a transparent sand EICP grouting test device and a test method thereof taking into account pore solution seepage, so as to solve the problems existing in the prior art.

[0005] The technical solution adopted to achieve the purpose of the present invention is as follows: a transparent sand EICP grouting test device considering pore solution seepage, including a grouting diffusion unit and a laser imaging unit.

[0006] The grouting diffusion unit includes a transparent soil model box, a water head control device, a peristaltic pump, and a discharge liquid collection box. The transparent soil model box is a rectangular box with a cover. The top cover of the transparent soil model box is provided with a pore solution injection hole and an EICP single-phase mixed slurry injection hole. The water head control device is connected to the pore solution injection hole via a pipeline. The peristaltic pump is connected to the EICP single-phase mixed slurry injection hole via a pipeline. The transparent soil sample solid particles are filled in layers in the inner cavity of the transparent soil model box. The discharge liquid collection box is connected to the inner cavity of the transparent soil model box via a pipeline. Different fluorescent labeling strategies are used for the pore solution, the EICP single-phase mixed slurry, and the transparent soil solid particles. The refractive index of the pore solution is the same as the refractive index of the transparent soil sample solid particles.

[0007] The laser imaging unit includes a laser emitter and a high-speed digital camera, both of which are arranged outside the transparent soil model box.

[0008] During operation, the laser emitted by the laser emitter forms a laser plane in the transparent soil. The shooting direction of the high-speed digital camera is located in the normal direction of the laser plane. The pore solution is injected into the transparent soil model box through the head controller. After the seepage field is stabilized, the EICP single-phase mixed slurry is injected into the transparent soil model box through the peristaltic pump. Multi-color laser irradiation is used to make the pore solution, EICP single-phase mixed slurry and transparent soil solid particles show differentiated color characteristics, achieving a visual quantitative characterization of the dynamic distribution of components. PIV and PTV techniques are used to observe the changes in slurry flow diffusion and slurry flow velocity, and PLIF technology is used to observe the precipitation process of calcium carbonate in the pores of soil particles.

[0009] Furthermore, a buffer layer I is provided between the transparent soil sample solid particles and the box cover. A buffer layer II is provided between the transparent soil sample solid particles and the box bottom. Both buffer layers I and II are provided with uniform diversion channels. Buffer layer I is a 10 mm thick organic glass porous plate with a 1 mm pore size distributed in a plum blossom array and a pore density of 20 pores / dm 2 The buffer layer II is a 316L stainless steel sintered filter with a mesh size of 200. The ratio of the distance between the buffer layer I and the buffer layer II to the sample height is 1:5.

[0010] Furthermore, the laser transmitter is mounted on a lifting bracket, the high-speed digital camera is slidably mounted on a slide rail, and a long-pass filter is installed at the front end of the lens of the high-speed digital camera.

[0011] Furthermore, the EICP single-phase mixed slurry contains hollow glass microspheres as tracer particles, the pore solution is dyed with Nile red dye, and the solid particles of the transparent soil sample are colored with purple fluorescent pigment.

[0012] Furthermore, the transparent soil sample solid particles are fused quartz sand. The pore solution is mineral oil. Fused quartz sand exhibits chemical stability and extremely low corrosion rates in the weakly alkaline, ionic environment involved in the EICP reaction. The lipid material used in the pore solution is relatively stable and does not react with the grouting material. The refractive index of the generated calcium carbonate is highly matched to that of the quartz sand, achieving both bonding and transparency.

[0013] Furthermore, the transparent soil model box is made of highly light-transmitting acrylic material.

[0014] Furthermore, the water head control device adopts an electronic water head controller with an accuracy of ±1%, and the maximum controllable water head difference is 2m.

[0015] Furthermore, the peristaltic pump has a flow rate range of 0.1 to 100 mL / min and a linear error of <0.5%.

[0016] The present invention also discloses a test method according to the above device, comprising the following steps:

[0017] 1) Place the transparent soil sample solid particles in the transparent soil model box up to the test height.

[0018] 2) Inject pore solution into the transparent soil model box through the head controller.

[0019] 3) After the seepage field stabilizes, the peristaltic pump is started synchronously to inject the EICP single-phase mixed slurry into the transparent soil model box.

[0020] 4) Use multi-color laser to irradiate transparent soil. Use high-speed digital camera to capture the cross-sectional image of transparent soil.

[0021] 5) Save the test process image, turn off the test instrument, and organize the test equipment.

[0022] 8) Use PIV and PTV technology to process the test images, obtain the slurry flow diffusion and slurry flow velocity changes and record the data.

[0023] 9) PLIF technology is used to process the test images to obtain the process law of calcium carbonate precipitation in the pores of soil particles.

[0024] Furthermore, after step 9), there is also a step of analyzing the changes in pore structure, quantifying the amount of calcium carbonate precipitation, revealing the temporal and spatial distribution law of calcium carbonate precipitation, and the law of particle release under hydraulic action.

[0025] The technical effects of the present invention are unquestionable:

[0026] A. The experimental results reveal the temporal and spatial distribution patterns of calcium carbonate precipitation and the release patterns of particles under hydraulic action, providing a theoretical basis for optimizing the biogrouting process in shield tunnels.

[0027] B. The experimental device can accurately distinguish and dynamically track the seepage-grouting-sedimentation process, breaking through the opacity limitations of traditional sand models.

[0028] C. Reveal the changes in EICP slurry flow diffusion and slurry flow velocity under dynamic water conditions, guide the intelligent optimization of grouting parameters in water-rich strata, and provide new ideas for the prevention and control of water leakage in shield tunnels in water-rich sand layers.

[0029] D. The test equipment is reasonable, easy and quick to operate, and has high feasibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 Schematic diagram of the test device structure;

[0031] Figure 2 This is a side view of the test device structure.

[0032] In the figure: transparent soil model box 1, water head control device 2, peristaltic pump 3, discharged liquid collection box 4, laser transmitter 5, high-speed digital camera 6, long-pass filter 7, slide rail 8. DETAILED DESCRIPTION

[0033] The present invention will be further described below with reference to the following examples, but it should not be understood that the scope of the present invention is limited to the following examples. Without departing from the above technical ideas of the present invention, various substitutions and modifications can be made according to common technical knowledge and customary means in the art, and all should be included in the scope of protection of the present invention.

[0034] Example 1:

[0035] See also Figure 1 and Figure 2 This embodiment provides a transparent sand EICP (enzymeinduced carbonate precipitation) grouting test device considering pore solution seepage, including a grouting diffusion unit and a laser imaging unit.

[0036] The grouting diffusion unit includes a transparent soil model box 1, a water head control device 2, a peristaltic pump 3 and a discharge liquid collection box 4. The transparent soil model box 1 is a rectangular box with a cover. The top cover of the transparent soil model box 1 is provided with a pore solution injection hole and an EICP single-phase mixed slurry injection hole. The water head control device 2 is connected to the pore solution injection hole through a pipeline. The peristaltic pump 3 is connected to the EICP single-phase mixed slurry injection hole through a pipeline. The transparent soil sample solid particles are filled in layers in the inner cavity of the transparent soil model box 1. The discharge liquid collection box 4 is connected to the inner cavity of the transparent soil model box 1 through a pipeline. Different fluorescent labeling strategies are used for the pore solution, the EICP single-phase mixed slurry and the transparent soil solid particles. The refractive index of the pore solution is the same as the refractive index of the transparent soil sample solid particles.

[0037] The laser imaging unit includes a laser emitter 5 and a high-speed digital camera 6. The laser emitter 5 and the high-speed digital camera 6 are both arranged outside the transparent soil model box 1.

[0038] During operation, the laser emitted by the laser emitter 5 forms a laser plane in the transparent soil. The shooting direction of the high-speed digital camera 6 is located in the normal direction of the laser plane. The pore solution is injected into the transparent soil model box 1 through the head controller 2. After the seepage field is stabilized, the EICP single-phase mixed slurry is injected into the transparent soil model box 1 through the peristaltic pump 3. Multi-color laser irradiation is used to make the pore solution, EICP single-phase mixed slurry and transparent soil solid particles show differentiated color characteristics, achieving a visual quantitative characterization of the dynamic distribution of components. PIV and PTV techniques are used to observe the changes in slurry flow diffusion and slurry flow velocity, and PLIF technology is used to observe the precipitation process of calcium carbonate in the pores of soil particles.

[0039] Example 2:

[0040] The main contents of this embodiment are the same as those of embodiment 1, wherein a buffer layer I is provided between the transparent soil sample solid particles and the box cover. A buffer layer II is provided between the transparent soil sample solid particles and the box bottom. Both buffer layers I and II are provided with uniform diversion channels. Buffer layer I is a 10 mm thick organic glass porous plate with a 1 mm pore size distributed in a plum blossom array and a pore density of 20 pores / dm 2 The buffer layer II is a 316L stainless steel sintered filter with a mesh size of 200. The ratio of the distance between the buffer layer I and the buffer layer II to the sample height is 1:5.

[0041] Example 3:

[0042] The main contents of this embodiment are the same as those of embodiment 1 or 2, wherein the laser emitter 5 is mounted on a lifting bracket, the high-speed digital camera 6 is slidably mounted on a slide rail 8, and a long-pass filter 7 is installed at the front end of the lens of the high-speed digital camera 6.

[0043] Example 4:

[0044] The main contents of this embodiment are the same as those of Examples 1 to 3, except that the EICP single-phase mixed slurry contains hollow glass microspheres as tracer particles, the pore solution is dyed with Nile red dye, and the solid particles of the transparent soil sample are colored with a purple fluorescent pigment.

[0045] Example 5:

[0046] This example is primarily similar to Examples 1-4, except that the transparent soil sample solid particles are fused quartz sand. The pore solution is mineral oil. Fused quartz sand exhibits chemical stability and a very low corrosion rate in the weakly alkaline, ionic environment involved in the EICP reaction. The lipid material used in the pore solution is relatively stable and does not react with the grouting material. The refractive index of the generated calcium carbonate is highly matched to that of the quartz sand, achieving both bonding and transparency.

[0047] Example 6:

[0048] The main contents of this embodiment are the same as those of embodiments 1 to 5, wherein the transparent soil model box 1 is made of highly light-transmitting acrylic material.

[0049] Example 7:

[0050] The main contents of this embodiment are the same as those of embodiments 1 to 6, wherein the water head control device 2 adopts an electronic water head controller with an accuracy of ±1%, and the maximum adjustable water head difference is 2m.

[0051] Example 8:

[0052] The main contents of this embodiment are the same as those of embodiments 1 to 7, wherein the flow rate range of the peristaltic pump 3 is 0.1 to 100 mL / min, and the linear error is less than 0.5%.

[0053] Example 9:

[0054] This embodiment provides a test method for the device according to embodiments 1 to 8, comprising the following steps:

[0055] 1) Place transparent soil sample solid particles in the transparent soil model box 1 up to the test height.

[0056] 2) Inject pore solution into the transparent soil model box 1 through the water head controller 2.

[0057] 3) After the seepage field stabilizes, the peristaltic pump 3 is simultaneously started to inject the EICP single-phase mixed slurry into the transparent soil model box 1.

[0058] 4) The transparent soil is irradiated with a multi-color laser, and a high-speed digital camera 6 captures an image of the transparent soil cross section.

[0059] 5) Save the test process image, turn off the test instrument, and organize the test equipment.

[0060] 8) Use PIV and PTV technology to process the test images, obtain the slurry flow diffusion and slurry flow velocity changes and record the data.

[0061] 9) PLIF technology is used to process the test images to obtain the process law of calcium carbonate precipitation in the pores of soil particles.

[0062] Example 10:

[0063] This embodiment provides a test method for the device according to embodiments 1 to 8, comprising the following steps:

[0064] 1) Design an experimental plan and make a transparent soil model box 1.

[0065] 2) Prepare a transparent sand sample. After grading and screening the fused quartz sand that simulates the sand particles, it is colored with a purple fluorescent pigment and transparent soil is prepared until the experimental height is reached.

[0066] 3) Start the seepage control system and inject a pore solution simulating seepage into the box through the top head controller 2. Use Nile red dye to dye the pore solution in advance, adjust the seepage velocity, and use the bottom buffer layer to stabilize the flow field.

[0067] 4) After the seepage field stabilizes, peristaltic pump 3 is simultaneously started to inject the EICP single-phase mixed slurry into the fused quartz sand through the buffer layer at the top of the transparent soil model box. The EICP single-phase mixed slurry contains hollow glass microspheres as tracer particles of the EICP slurry. The grouting pressure and flow rate are dynamically adjusted according to the seepage intensity.

[0068] 5) The laser emitter 5 is adjusted to green light. At this time, the fluorescent dyed particles appear black, the EICP slurry containing hollow glass microspheres appears green, and the pore solution dyed with Nile red dye appears orange. The high-speed digital camera 6 is used with a long-pass filter 7 to capture the transparent soil cross-section image.

[0069] 6) The laser emitter 5 is adjusted to ultraviolet laser irradiation. The fluorescent particles in the fused silica sand absorb the purple light and appear red. The resulting calcium carbonate precipitate has a refractive index similar to that of the transparent soil, a smaller particle size, and no fluorescence, and can be distinguished from the fused silica sand particles. The high-speed digital camera 6 is used in conjunction with the long-pass filter 7 to capture an image of the transparent soil cross-section.

[0070] 7) Save the test process image, turn off the test instrument, and organize the test equipment.

[0071] 8) Use PIV and PTV technology to process the test images, obtain the slurry flow diffusion and slurry flow velocity changes and record the data.

[0072] 9) PLIF technology is used to process the test images to obtain the process law of calcium carbonate precipitation in the pores of soil particles.

[0073] 10) Analyze pore structure changes, quantify the amount of calcium carbonate precipitation, reveal the temporal and spatial distribution of calcium carbonate precipitation, and reveal the patterns of particle release under hydraulic pressure. This provides a theoretical basis for optimizing the biogrouting process in shield tunnels and offers new ideas for preventing water seepage in shield tunnels in water-rich sand layers.

Claims

1. A transparent sand EICP grouting test device considering pore solution seepage, characterized by: It includes a grouting diffusion unit and a laser imaging unit; The grouting diffusion unit comprises a transparent soil model box (1), a water head control device (2), a peristaltic pump (3) and a discharge liquid collection box (4); the transparent soil model box (1) is a rectangular box with a cover; a pore solution injection hole and an EICP single-phase method mixed slurry injection hole are provided on the top cover of the transparent soil model box (1); the water head control device (2) is connected to the pore solution injection hole through a pipeline; the peristaltic pump (3) is connected to the EICP single-phase method mixed slurry injection hole through a pipeline; transparent soil sample solid particles are filled in layers in the inner cavity of the transparent soil model box (1); the discharge liquid collection box (4) is connected to the inner cavity of the transparent soil model box (1) through a pipeline; the pore solution, the EICP single-phase method mixed slurry and the transparent soil solid particles adopt different fluorescent labeling strategies; the refractive index of the pore solution is the same as the refractive index of the transparent soil sample solid particles; The laser imaging unit comprises a laser emitter (5) and a high-speed digital camera (6); the laser emitter (5) and the high-speed digital camera (6) are both arranged outside the transparent soil model box (1); During operation, the laser emitted by the laser emitter (5) forms a laser plane in the transparent soil; the shooting direction of the high-speed digital camera (6) is located in the normal direction of the laser plane; the pore solution is injected into the transparent soil model box (1) through the water head controller (2); after the seepage field is stabilized, the EICP single-phase mixed slurry is injected into the transparent soil model box (1) through the peristaltic pump (3); multi-color laser irradiation is used to make the pore solution, the EICP single-phase mixed slurry and the transparent soil solid particles present differentiated color characteristics, thereby achieving a visual quantitative characterization of the dynamic distribution of the components; PIV and PTV technologies are used to observe the changes in the slurry flow diffusion and slurry flow velocity, and PLIF technology is used to observe the precipitation process of calcium carbonate in the pores of the soil particles.

2. The transparent sand EICP grouting test device considering pore solution seepage according to claim 1, characterized in that: A buffer layer I is set between the transparent soil sample solid particles and the box cover; a buffer layer II is set between the transparent soil sample solid particles and the box bottom; both buffer layers I and II are provided with uniform diversion channels; the buffer layer I is a 10mm thick organic glass porous plate with a 1mm pore diameter and a plum blossom array distribution, with a pore density of 20 pores / dm 2 ; The buffer layer II is a 316L stainless steel sintered filter with a mesh size of 200 mesh; the ratio of the spacing between the buffer layer I and the buffer layer II to the sample height is 1:

5.

3. The transparent sand EICP grouting test device considering pore solution seepage according to claim 1, characterized in that: The laser emitter (5) is mounted on a lifting bracket; the high-speed digital camera (6) is slidably mounted on a slide rail (8); and a long-pass filter (7) is installed at the front end of the lens of the high-speed digital camera (6).

4. The transparent sand EICP grouting test device considering pore solution seepage according to claim 1, characterized in that: The EICP single-phase method mixed slurry contains hollow glass microspheres as tracer particles; the pore solution is dyed with Nile red dye; and the solid particles of the transparent soil sample are colored with purple fluorescent pigment.

5. The transparent sand EICP grouting test device considering pore solution seepage according to claim 1, characterized in that: The solid particles of the transparent soil sample are fused quartz sand; and the pore solution is mineral oil.

6. The transparent sand EICP grouting test device considering pore solution seepage according to claim 1, characterized in that: The transparent soil model box (1) is made of a highly light-transmitting acrylic material.

7. The transparent sand EICP grouting test device considering pore solution seepage according to claim 1, characterized in that: The water head control device (2) adopts an electronic water head controller with an accuracy of ±1%, and the maximum adjustable water head difference is 2m.

8. The transparent sand EICP grouting test device considering pore solution seepage according to claim 1, characterized in that: The peristaltic pump (3) has a flow rate range of 0.1 to 100 mL / min and a linear error of less than 0.5%.

9. A method for testing the device according to claims 1 to 8, characterized in that: The following steps are involved: 1) placing transparent soil sample solid particles in a transparent soil model box (1) up to the test height; 2) injecting pore solution into the transparent soil model box (1) through the water head controller (2); 3) After the seepage field is stabilized, the peristaltic pump (3) is simultaneously turned on to inject the EICP single-phase mixed slurry into the transparent soil model box (1); 4) using a multi-color laser to illuminate the transparent soil; and using a high-speed digital camera (6) to capture an image of the transparent soil cross section; 5) Save the test process image, turn off the test instrument, and organize the test equipment; 8) Use PIV and PTV technology to process the test images, obtain the slurry flow diffusion and slurry flow velocity changes and record the data; 9) PLIF technology is used to process the test images to obtain the process law of calcium carbonate precipitation in the pores of soil particles.

10. The transparent sand EICP grouting test device considering pore solution seepage according to claim 9, characterized in that: After step 9), there are steps for analyzing the changes in pore structure, quantifying the amount of calcium carbonate precipitation, revealing the temporal and spatial distribution of calcium carbonate precipitation, and the law of particle release under hydraulic action.

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