Improved single-phase injector testing device and method

Abstract

The invention discloses an improved single-phase injector testing device and method, and particularly relates to the technical field of biologically solidified rock-soil bodies. Comprising a container; the porous mold is placed in the container; the geotechnical cloth is attached to the interior of the porous mold, and the geotechnical cloth is used for wrapping the sample; the two permeable stones are respectively arranged on the upper side and the lower side of the sample; the urease solution is pumped into the top of the container from the top of the container through the first input pipe and permeates through the permeable stone on the upper side; the cementing liquid is pumped into a cavity between the container and the porous mold from the top of the container through a second input pipe; the circulating assembly is used for conveying the reaction residual liquid in the container to the top of the container again, and the reaction residual liquid permeates through the permeable stone on the upper side. By adopting the technical scheme provided by the invention, the problems that the reaction residual liquid of the existing single-phase injector test device cannot be recycled, the reaction is not uniform and the like are solved, and the reutilization of resources and the more uniform curing effect are realized.

Description

Technical Field

[0001] This invention relates to the field of bio-solidified soil and rock technology, and in particular to an improved single-phase injector test apparatus and method. Background Technology

[0002] In recent years, global environmental problems have become increasingly severe. Human activities, such as the greenhouse effect and land pollution, have placed enormous pressure on the Earth's ecosystem. Against this backdrop, countries are actively advocating the use of green, natural, energy-saving, and environmentally friendly materials to reduce negative environmental impacts and promote sustainable development.

[0003] In the field of geotechnical engineering, traditional geotechnical reinforcement techniques, such as dynamic compaction, drainage consolidation, and grouting, have long held a dominant position. However, these traditional techniques have many drawbacks. From an economic perspective, they are expensive, increasing the cost of engineering projects; in terms of construction time, they often require long periods, affecting the overall progress of the project; in terms of resource consumption, a large amount of manpower, material resources, and energy are consumed, which does not meet current requirements for energy conservation and environmental protection. More seriously, some traditional techniques can also pollute the surrounding environment during construction, further disrupting the ecological balance. Therefore, finding a new, environmentally friendly geotechnical treatment technology is urgently needed.

[0004] Biosolidification (EICP / MICP) has emerged as a new technology for soil and rock treatment. It is based on the principle that organisms generate inorganic minerals through the regulation of biomolecules, utilizing bio-induced carbonate formation to solidify the soil. This technology offers numerous advantages, including being environmentally friendly and resource-saving, aligning with current requirements for sustainable development and gradually becoming a research hotspot in the field of geotechnical engineering.

[0005] In biosolidification technology, the solidification method plays a crucial role in the distribution of calcium carbonate in EICP / MICP-solidified soil. Currently, the four commonly used solidification methods in laboratory tests are immersion, pre-mixing, single-phase injection, and two-phase injection. Extensive research and practical verification have shown that single-phase injection exhibits the most outstanding reinforcement effect, more effectively achieving soil consolidation and improving soil strength and stability.

[0006] Despite the significant advantages of single-phase injection, traditional single-phase injection methods have the following drawbacks:

[0007] 1) The urease solution reacts rapidly with the cementitious liquid at the sample inlet, resulting in the deposition of a large amount of calcium carbonate at the inlet. This localized excessive deposition not only blocks the injection channel and affects the subsequent injection of reagents, but also leads to uneven distribution of calcium carbonate in the soil, reducing the overall reinforcement effect;

[0008] 2) Due to the one-way injection mode, the flow and reaction of the reagent at the bottom of the sample are restricted, resulting in insufficient reaction in the bottom area of ​​the sample, which prevents the formation of uniform and dense calcium carbonate precipitate, thus affecting the reinforcement quality of the bottom of the soil.

[0009] 3) The reaction residue is directly discharged and cannot be recycled, resulting in a reagent utilization rate of less than 50%, which increases the cost and does not meet environmental protection requirements.

[0010] Given the aforementioned shortcomings of the traditional single-phase injection method, it is necessary to improve the existing single-phase injector test equipment to enhance the effectiveness and efficiency of bio-solidification technology and promote the development of geotechnical engineering towards a more environmentally friendly and efficient direction. Summary of the Invention

[0011] The present invention aims to provide an improved single-phase injector test apparatus and method, which solves the problems of reagent inlet deposition and blockage, insufficient reaction at the bottom of the sample, and low reagent utilization rate due to the inability to recycle reaction residue in existing single-phase injector test apparatuses.

[0012] To achieve the above objectives, the technical solution of the present invention is as follows: an improved single-phase injector testing apparatus and method, comprising:

[0013] container;

[0014] A porous mold, which is placed inside a container, has small holes on its sidewalls for liquid flow.

[0015] Geotextile, which is attached to the inside of a porous mold and is used to cover the sample;

[0016] Two permeable stones are respectively placed on the upper and lower sides of the sample, and each permeable stone is against the container.

[0017] Urease solution, which is pumped from the top of the container through a first inlet tube and permeates to the top of the sample via the permeable stone on the upper side;

[0018] The cementing liquid is pumped from the top of the container into the cavity between the container and the porous mold through a second inlet pipe, and seeps into the sample from the side through the small holes of the porous mold.

[0019] A circulation assembly for re-transporting reaction residues from the container back to the top of the container and permeating through the permeable stone on the upper side.

[0020] Furthermore, the circulation assembly includes an outlet conduit that is connected to the bottom of the container and abuts against the permeable stone. The outlet conduit is connected to a collection box, and a single-head peristaltic pump is connected to the collection box. The other end of the single-head peristaltic pump is provided with a circulation pipe that is connected to the top of the container and abuts against the permeable stone.

[0021] Furthermore, the thickness of the permeable stone is 5mm.

[0022] With the above settings, the permeable stone can achieve both good solution flow and structural support under the subsequent thickness conditions.

[0023] Furthermore, the second input tube is closely attached to the inner wall of the porous mold.

[0024] With the above setup, the cementing liquid can be guided to flow in evenly and slowly along the wall using the second input pipe.

[0025] Furthermore, the method of using the experimental apparatus is as follows:

[0026] S1. Wrap the soil sample in geotextile and place two permeable stones on the upper and lower sides of the soil sample respectively. Then put the soil sample, geotextile and permeable stones into the porous mold and put the porous mold into the container.

[0027] S2. The dual-head peristaltic pump pumps urease solution and cementing liquid into the permeable stone located at the top of the porous mold and the cavity between the porous mold and the container through the first input pipe and the second input pipe, respectively.

[0028] S3. The residual liquid after the reaction is reinjected into the top of the soil sample through the circulation component;

[0029] S4. Stop injecting when the water level reaches the top. After the water level gradually drops to the bottom of the container, take out the soil sample for the next step of curing.

[0030] Furthermore, the flow rate of the urease solution is set to 2 ml / min; the flow rate of the cementing solution is 1.5 ml / min; and the flow rate of the single-head peristaltic pump is set to 60% of the total flow rate of the dual-head peristaltic pump. If the water level continues to rise, the flow rate of the single-head peristaltic pump is reduced by 5% increments, and vice versa.

[0031] The above settings allow the urease solution to migrate at a faster rate within the sample, thereby promoting a more thorough encounter and reaction with the laterally penetrating binder inside the sample, preventing the reaction from concentrating in the inlet area; at the same time, this maintains the dynamic stability of the liquid level within the container.

[0032] Compared with existing technologies, the beneficial effects of this solution are:

[0033] 1. Compared with traditional grouting methods, the experimental device of this invention injects urease solution from the top and cementing liquid from the outer container of the mold. Through staining tracer experiments, it is confirmed that the two solutions meet and react in the middle part of the sample. Then, the urease solution continues to flow downward under the influence of gravity and reacts with the cementing liquid already injected at the bottom. The cementing liquid continues to flow upward through the holes on the mold with the water level and reacts with the urease solution already injected at the top. Moreover, the pH value of the cementing liquid is 1.25 to 3.5, which is consistent with the single-phase low pH injection method. This injection method achieves uniform reaction inside the sample and enhances the curing effect.

[0034] 2. This invention features a single-head peristaltic pump to extract the residual reaction liquid and continue injecting it into the sample, thus achieving the goal of reuse, environmental protection, and energy conservation.

[0035] 3. In this invention, the injection rate of the solution can be precisely adjusted by regulating the independent flow rate control module of the dual-head peristaltic pump, thereby allowing for flexible study of the effects of different ratios and flow rate conditions on the bio-curing reaction process and effect. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the structure of an improved single-phase injector test device according to the present invention;

[0037] Figure 2 This is a cross-sectional view of the container in an improved single-phase injector test apparatus according to the present invention;

[0038] Figure 3 This is a schematic diagram of the structure of the rubber plug located at the top in an improved single-phase injector test device of the present invention;

[0039] Figure 4 This is a schematic diagram of the structure of the rubber plug located at the bottom in an improved single-phase injector test device of the present invention.

[0040] The reference numerals in the accompanying drawings include: 1. Container; 2. Porous mold; 3. Upper rubber stopper; 4. Permeable stone; 5. Geotextile; 6. Single-head peristaltic pump; 7. Double-head peristaltic pump; 8. Urease beaker; 9. Cementing liquid beaker; 10. Collection box; 11. First input pipe; 12. Second input pipe; 13. Liquid outlet conduit; 14. Liquid outlet pipe; 15. Circulation pipe; 16. Lower rubber stopper. Detailed Implementation

[0041] The present invention will be further described in detail below through specific embodiments:

[0042] Example

[0043] like Figures 1 to 4 As shown, an improved single-phase injector test apparatus includes:

[0044] Container 1 is designed with open ends and is made of acrylic sheet to facilitate observation of the experimental process inside. Each open end of container 1 is equipped with an upper rubber stopper 3 and a lower rubber stopper 16 to ensure that the reaction liquid does not leak out. The upper rubber stopper 3 has three first through holes, and the lower rubber stopper 16 has one second through hole. The ends of the first and second through holes of the upper rubber stopper 3 are in contact with the surfaces of the corresponding permeable stones 4. Two of the three first through holes are located directly above the upper permeable stone 4, and the third first through hole is located between the inner wall of container 1 and the porous mold 2.

[0045] A porous mold 2 is placed inside container 1, and the diameter of the porous mold 2 is smaller than the inner diameter of container 1. The porous mold 2 is 5 mm away from the top and bottom of container 1. The porous mold 2 is composed of two half molds joined together. After the sample is filled, it is fixed with rubber bands. Each half mold has multiple small holes arranged circumferentially on its side wall for liquid flow, and the spacing between adjacent small holes is 3 mm.

[0046] Geotextile 5 is attached to the inside of the porous mold 2. Geotextile 5 is used to cover the soil sample to ensure that the solution can penetrate into the mudstone while the shape of the soil sample does not change.

[0047] Two permeable stones 4, each 5 mm thick, are placed on the top and bottom sides of the sample, respectively. These stones ensure that the solution can flow through the mudstone without losing mudstone particles. Each stone 4 abuts against two rubber stoppers.

[0048] Urease solution is placed in urease beaker 8. The urease solution is pumped from the top of container 1 through the first input tube 11 and permeates to the top of the sample through the permeable stone 4 on the upper side.

[0049] The cementing solution is contained in cementing solution beaker 9. In this embodiment, the cementing solution is an equimolar mixture of CaCl2 and urea. Before the experiment, the pH value is adjusted to 1.25 using dilute hydrochloric acid. The cementing solution is pumped from the top of container 1 into the cavity between container 1 and porous mold 2 through the second input tube 12, and then seeps into the sample from the side through the small holes of porous mold 2. The second input tube 12 is in close contact with porous mold 2. In this embodiment, urease solution and cementing solution are contained in urease beaker 8 and cementing solution beaker 9, respectively. A dual-head peristaltic pump 7 is installed on both the first input tube 11 and the second input tube 12, thereby controlling the flow rate in the first input tube 11 and the second input tube 12.

[0050] A circulation assembly is used to re-transport the reaction residue in container 1 back to the permeable stone 4 at the top of container 1. In this embodiment, the circulation assembly includes an outlet conduit 13 inserted into the second through hole. The end of the outlet conduit 13 abuts against the permeable stone 4. The outlet conduit 13 is connected to a collection box 10 located outside container 1. An outlet pipe 14 is connected to the collection box 10. A single-head peristaltic pump 6 is installed on the outlet pipe 14. The outlet end of the single-head peristaltic pump 6 is connected to a circulation pipe 15. The circulation pipe 15 is connected to the first through hole at the top of container 1 and abuts against the permeable stone 4.

[0051] The operating method of the experimental apparatus is as follows:

[0052] S1. Wrap the soil sample inside the geotextile 5, and place two permeable stones 4 on the upper and lower sides of the soil sample respectively. Then, put the soil sample, geotextile 5, and permeable stones 4 into the porous mold 2. Then, fill the container 1 with deionized water and maintain it for 20 minutes to check for leakage. Perform a sealing test on the container 1. After confirming that there is no risk of leakage, put the porous mold 2 into the container 1.

[0053] S2. Urease solution and cementing solution are pumped into the permeable stone 4 located at the top of the porous mold 2 and into the cavity between the porous mold 2 and the container 1 through the dual-head peristaltic pump 7 and the first and second input pipes, respectively. The flow rate of urease solution is set to 2 ml / min and the flow rate of cementing solution is set to 1.5 ml / min using the dual-head peristaltic pump 7.

[0054] S3. The residual liquid after the reaction flows from the outlet pipe 13 into the collection tank 10, and is then reinjected into the top of the soil sample through the outlet pipe 14, the single-head peristaltic pump 6, and the circulation pipe 15. The flow rate of the single-head peristaltic pump 6 is set to 60% of the total flow rate of the double-head peristaltic pump 7. If the water level continues to rise, the flow rate of the single-head peristaltic pump 6 is reduced in a 5% increment, and vice versa. In this scheme, the urease solution has a higher viscosity than the cementing liquid, and its migration rate within the sample is slower. On the other hand, the migration of the urease solution within the sample is necessarily slower than that of the cementing liquid within the cavity, so the flow rate of the urease solution needs to be set higher. At the same time, the flow rate of the single-head peristaltic pump 6 is lower than that of the double-head peristaltic pump 7. This is to prevent the urease and cementing liquid flowing out of the double-head peristaltic pump 7 from overflowing the container 1 due to too much solution before the flow rate of the single-head peristaltic pump 6 is too high.

[0055] S4. Stop injecting when the water level reaches the top. After the water level gradually drops to the bottom of container 1, remove the soil sample for the next curing step. After the test, the following results were obtained: calcium conversion efficiency (CCE) was 65%, calcium carbonate content (CCC) of the sample reached 7.2%, and unconfined compressive strength reached 420 kPa.

[0056] Example 2

[0057] The only difference between this embodiment and Example 1 is that the pH value of the cementing solution is adjusted to 2.5, while the other conditions are exactly the same as those of the comparative example.

[0058] After the experiment, the following results were obtained: calcium conversion efficiency (CCE) was 75%, calcium carbonate content (CCC) of the sample reached 7.8%, and unconfined compressive strength reached 480 kPa.

[0059] Example 3:

[0060] The only difference between this embodiment and Example 1 is that the pH value of the cementing solution is adjusted to 3.5, while the other conditions are exactly the same as those of the comparative example.

[0061] After the experiment, the following results were obtained: calcium conversion efficiency (CCE) was 62%, calcium carbonate content (CCC) of the sample reached 6.8%, and unconfined compressive strength reached 400 kPa.

[0062] Comparative Example

[0063] The only difference between this comparative example and Example 1 is that it does not have the circulation component of Example 1, and the pH value of the cementitious solution is 2.5.

[0064] The test results were as follows: calcium conversion efficiency (CCE) was 50%, calcium carbonate content (CCC) of the sample was 6.0%, and unconfined compressive strength was 300 kPa.

[0065] The above data clearly demonstrates that combining the circulating component of this invention with a single-phase injection method using a binder solution with a pH value of 1.25~3.5 can achieve a synergistic effect, significantly improving the curing effect and reagent utilization. This confirms the outstanding advantages of this solution in terms of environmental protection and economy.

[0066] The above are merely embodiments of the present invention, and common knowledge such as specific structures and / or characteristics in the solutions are not described in detail here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the structure of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. An improved single-phase injector test apparatus, characterized in that, include: Container (1); A porous mold (2) is placed inside a container (1), and the side wall of the porous mold is provided with small holes for liquid to flow through. Geotextile (5), which is attached to the inside of the porous mold (2), is used to cover the sample; Two permeable stones (4) are respectively placed on the upper and lower sides of the sample, and each permeable stone (4) is against the container (1); Urease solution, which is pumped from the top of container (1) through the first input tube (11) and permeates to the top of the sample through the permeable stone (4) on the upper side; The cementing liquid is pumped from the top of the container (1) into the cavity between the container (1) and the porous mold (2) through the second input pipe (12), and seeps into the sample from the side through the small holes of the porous mold (2). A circulation assembly is used to re-transport the reaction residue at the bottom of container (1) to the top of container (1) and permeate through the permeable stone (4) on the upper side.

2. The improved single-phase injector test apparatus according to claim 1, characterized in that: The circulation assembly includes an outlet conduit (13), which is connected to the bottom of the container (1) and abuts against the permeable stone (4). The outlet conduit (13) is connected to a collection box (10), which is connected to a single-head peristaltic pump (6). The other end of the single-head peristaltic pump (6) is provided with a circulation pipe (15), which is connected to the top of the container (1) and abuts against the permeable stone (4).

3. The improved single-phase injector test apparatus according to claim 1, characterized in that: The thickness of the permeable stone (4) is 5 mm.

4. The improved single-phase injector test apparatus according to claim 1, characterized in that: The second input tube (12) is in close contact with the inner wall of the porous mold (2).

5. An improved single-phase injector test apparatus according to any one of claims 1-4, characterized in that: The method of using the experimental apparatus is as follows: S1. Wrap the soil sample in geotextile (5) and place two permeable stones (4) on the upper and lower sides of the soil sample respectively. Then put the soil sample, geotextile (5) and permeable stones (4) into the porous mold (2) and put the porous mold (2) into the container (1). S2, the dual-head peristaltic pump (7) pumps urease solution and cementing liquid into the permeable stone (4) located on the top of the porous mold (2) and into the cavity between the porous mold (2) and the container (1) through the first input pipe (11) and the second input pipe (12), respectively; S3. The residual liquid after the reaction is reinjected into the top of the soil sample through the circulation component; S4. Stop injecting when the water level reaches the top. After the water level gradually drops to the bottom of the container (1), take out the soil sample for the next step of curing.

6. The improved single-phase injector test apparatus according to claim 5, characterized in that: The flow rate of the urease solution is set to 2 ml / min; the flow rate of the cementing solution is 1.5 ml / min; the flow rate of the single-head peristaltic pump (6) is set to 60% of the total flow rate of the double-head peristaltic pump (7). If the water level continues to rise, the flow rate of the single-head peristaltic pump (6) is reduced by a 5% gradient, and vice versa.

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