Multi-field coupling model test monitoring device and method for evaluating microbial mineralization homogeneity

Abstract

The invention relates to a multi-field coupling model test monitoring device and method for evaluating microbial mineralization homogeneity. The device comprises a test model box, a pressurization system, a grouting system, a sampling system, a sensor assembly and a computer monitoring system. Compared with the prior art, the device is focused on researching the process of influence of different overlying stresses and grouting rates on microorganism mineralized and solidified soil in multiple environments of a biological field, a chemical field, a stress field, a hydraulic field and the like. The device can effectively evaluate the uniformity and effect of solidification and restoration of microorganism mineralized and solidified soil and the distribution condition of mineral content, and provides an important basis for researching the long-term safety of the microorganism mineralized and solidified soil. The scheme is of great significance to remediation and utilization of polluted soil and energy conservation and carbon reduction of engineering application.

Description

Technical Field

[0001] The present invention belongs to the technical field of microbial mineralization solidification, and relates to a multi-field coupling model test monitoring device and method for evaluating the homogeneity of microbial mineralization, and in particular to a bio-chemical-stress-hydraulic multi-field coupling model test monitoring device and method for evaluating the homogeneity of microbial mineralization. Background Art

[0002] Modern engineering construction requires more green, efficient, environmentally friendly and energy-saving soil improvement technologies. As a hot topic in soil solidification research, microbial induced carbonate precipitation technology has been widely used in the fields of remediation of contaminated soil and soft foundation reinforcement. This technology mainly promotes the hydrolysis of urea through the metabolic activities of microorganisms, generates a large amount of carbonate ions, and combines with free calcium ions to form calcium carbonate precipitates. These precipitates can fill the pores of the soil, thereby improving the strength of the soil. Microbial mineralization solidification technology has the advantages of low energy consumption, little disturbance to the soil, and less secondary pollution. At the same time, it can also achieve biological carbon fixation and energy conservation and environmental protection in the process of improving the engineering performance of the soil.

[0003] In recent years, with the rapid advancement of industrialization, industries such as agriculture, metallurgy and chemical industries have discharged a large amount of pollutants into the soil and water during their operations. This pollution not only restricts the redevelopment of land, but also poses a threat to the health and safety of surrounding residents. In addition, facing the increasingly complex engineering geological environment, the hydraulic and mechanical properties of many soils can no longer meet engineering needs. Factors such as hydraulic erosion, liquefaction tendency and freeze-thaw cycles often lead to engineering problems such as roadbed subsidence, slope instability and coastal erosion.

[0004] However, the current research on microbial mineralization solidified soil is mainly focused on the strength, permeability and environmental safety after solidification, and there are relatively few studies on the solidification effect of the solidified soil under multiple fields, as well as the scope and uniformity of solidification repair. Therefore, in order to further explore the uniformity of microbial mineralization solidified soil, it is necessary to develop a test device that can monitor and evaluate the distribution evolution law and mechanism of the hydraulic field, stress field, chemical field, biological field and mineral content of the soil during the solidification process in real time under different overburden pressures and grouting rates, so as to gain a deep understanding of the internal mechanism of the solidified soil, thereby providing a theoretical basis and optimal solution for energy conservation and emission reduction in the redevelopment of contaminated sites and biocarbon fixation in soil improvement engineering applications.

[0005] The present invention is proposed based on this. Summary of the invention

[0006] The purpose of the present invention is to provide a multi-field coupling model test monitoring device and method for evaluating the homogeneity of microbial mineralization, which can explore and evaluate the influence of overlying stress and grouting rate on the uniformity of solidified soil in a multi-field coupling environment.

[0007] The purpose of the present invention can be achieved by the following technical solutions:

[0008] In one aspect, the present invention provides a multi-field coupled model test monitoring device for evaluating the homogeneity of microbial mineralization, comprising:

[0009] A test model box, comprising a model box body for placing a test soil body, a sleeve surrounding the model box body, and a top cover covering the test soil body;

[0010] A grouting system, comprising a grouting pump and a grouting pipe connected to the grouting outlet of the grouting pump, wherein the grouting pipe is inserted into the test soil body along a height direction and has grouting holes on its side walls for injecting grout outwards;

[0011] A pressurizing system, comprising a pressurizing head located above the top cover and capable of moving up and down, the pressurizing head being configured to apply a preset pressure to the top cover;

[0012] A sampling system, comprising a sampling tube extending from the bottom into the test soil body of the model box;

[0013] And a monitoring system, which includes a sensor component pre-placed in the test soil and used to monitor multiple field data including stress and strain, pH, conductivity, ammonium ion concentration, pore water pressure, etc.

[0014] Furthermore, water outlet holes are distributed around the model box, and a liquid storage space for storing excess slurry discharged through the water outlet holes is formed between the model box and the sleeve.

[0015] Furthermore, the inner wall and the bottom of the model box are both affixed with filter paper, wherein the filter paper on the inner wall is used to filter the test soil, allowing only excess liquid to pass through and enter the liquid storage space between the sleeve and the model box, while the filter paper on the bottom is mainly used to prevent the test soil from sticking and being difficult to remove.

[0016] Furthermore, the model box is in a cylindrical shape, exemplarily with a height of 1 m, a wall thickness of 1 cm, and an inner diameter of 2 m.

[0017] Furthermore, the top cover is provided with a top cover opening for the grouting pipe to extend into. Exemplarily, the inner diameter of the top cover opening is 2.3 cm, and the top cover is divided into an upper and lower part, the lower part has a diameter of 199.9 cm and a thickness of 3 cm, and is used to match the size of the inner wall of the test box to press the test soil sample, and the upper part has a diameter of 207 cm and a thickness of 2 cm, which plays a sealing role.

[0018] Furthermore, the grouting system also includes a silicone hose and a soft and hard pipe joint connected in sequence to the outlet of the grouting pump, and the soft and hard pipe joint is also connected to the grouting pipe, wherein the grouting pipe is used to deliver grouting slurry to the test soil.

[0019] Furthermore, filter paper is attached to the outside of the grouting pipe to prevent test soil components from entering the inside of the grouting pipe and affecting the grouting effect.

[0020] Furthermore, the grouting holes on the side wall of the grouting pipe are evenly spaced in three rows, with an interval of 120° between two rows. Exemplarily, the vertical hole spacing between two adjacent grouting holes in each row is 2 cm.

[0021] Furthermore, the pressurizing system also includes a fixed frame and a hydraulic pump. The pressurizing head is arranged on the fixed frame, and the hydraulic pump provides power for up and down lifting.

[0022] Furthermore, the fixed frame includes a support rod and a top plate, the support rod is fixedly connected to the outer wall of the sleeve, the top plate is connected to the top of the support rod, and the pressure head is arranged on the top plate.

[0023] Furthermore, the sampling system also includes a filter head, a one-way valve and a sampling connecting hose. The filter head is arranged at one end of the sampling tube extending into the test soil. The sampling connecting hose is connected to the other end of the sampling tube. A one-way valve is also provided on the sampling connecting hose.

[0024] Exemplarily, the sampling end of the one-way valve is a Luer interface, and water samples are taken through a Luer syringe; the sampling tube has an outer diameter of 4 mm, a wall thickness of 1 mm, and a length of 55 cm.

[0025] Furthermore, sampling holes are distributed at the bottom of the model box. After the sampling tube is connected to the sampling hole, glass glue and rubber pads are used to seal the bottom of the sampling hole to prevent leakage and loosening.

[0026] Exemplarily, for a certain size of sleeve or test box, the sampling holes are located at 10 cm, 30 cm, 50 cm, 70 cm, and 90 cm from the center, respectively, arranged at 60° intervals, with a total of 30 water sampling points and a hole diameter of 5 mm.

[0027] Furthermore, the sensor assembly includes a distributed optical fiber sensor unit and an electronic sensor unit, wherein the distributed optical fiber sensor unit includes a stress strain sensor and is provided in a plurality of rows arranged in a vertical direction in the test soil.

[0028] Furthermore, the electronic sensor unit includes a pH sensor, a conductivity sensor, an ammonium ion concentration sensor, and a pore water pressure sensor.

[0029] Furthermore, each sensor in the sensor assembly is connected to an external computer unit via a wire extending out of the model box.

[0030] In the present invention, a stress field and its stress strain sensor are provided to explore the effects of overburden pressure on stress distribution and deformation during the solidification process, evaluate its influence on the uniformity of repair, and determine the optimal pressure conditions to improve the efficiency of repair. The hydraulic field and its pore water pressure sensor are used to study the distribution characteristics of pore water pressure at different grouting rates to understand the diffusion of slurry and its effect on uniformity. The biological field and its viable bacteria count determination are used to evaluate the effects of microbial distribution and activity on solidification efficiency and uniformity. The chemical field and its pH sensor, conductivity sensor, and ammonium ion concentration sensor are intended to monitor the effects of the soil chemical environment on the uniformity of soil solidification and the migration and transformation process.

[0031] On the other hand, the present invention also provides a multi-field coupling model test monitoring method for evaluating the homogeneity of microbial mineralization, which is based on the above-mentioned monitoring device and comprises the following steps:

[0032] S1. Place the test soil in the model box by layered compaction, and simultaneously arrange the sampling system, grouting system, and monitoring system. After filling the test soil, cover the top cover;

[0033] S2. Adjust the pressurization system to apply a preset pressure to the test soil;

[0034] S3, adjusting the grouting system to perform grouting operation according to the preset grouting rate;

[0035] S4. After the grouting is completed, the test soil is sampled through the sampling system and the number of viable bacteria and urea concentration are measured, and the stress-hydraulic-chemical-biological multi-field data including stress-strain, pH, conductivity, ammonium ion concentration, and pore water pressure monitored by the monitoring system are recorded in real time;

[0036] S5, repeat S3 and S4 until the test soil is solidified;

[0037] S6. Dry the test soil after demolition, conduct a micro cone penetration test, measure the strength of the test soil, cut and sample the soil near each sampling port, and use the acid washing method to measure the calcite content. The test is completed.

[0038] The model test device provided by the present invention is used to study the uniformity law and mechanism of microbial mineralization and solidification soil restoration under the influence of grouting rate and overburden pressure by stress-hydraulic-chemical-biological multi-field coupling, and studies the uniformity of solidification and restoration of microbial mineralization and solidification soil under the influence of different grouting rates and different overburden pressures from the aspects of stress field, hydraulic field, chemical field, biological field, mineral distribution, etc. The device of the invention can effectively evaluate the uniformity of solidification of microbial mineralization and solidification soil at different depths and different grouting rates by real-time monitoring the parameters of the chemical field, biological field, stress field and hydraulic field of microbial mineralization and solidification soil, and provide a research basis for the restoration and redevelopment of contaminated sites and the energy-saving and emission-reduction biological carbon fixation in soil improvement engineering applications. The present application scheme is of great significance to the restoration scope and uniformity of microbial mineralization and solidification soil.

[0039] Compared with the prior art, the present invention has the following advantages:

[0040] (1) The existing technology focuses on analyzing the strength, permeability and environmental safety of microbial mineralized soil, but there is little discussion on the scope of solidification and repair, as well as the uniformity of repair and solidification under different ground depth conditions and grouting rates. The device of the present invention can simulate different ground depths by setting different overburden pressures and setting different grouting rates, thereby effectively evaluating the uniformity of microbial mineralized soil under various conditions, and providing an efficient and reasonable solution for energy conservation and emission reduction of biocarbon fixation in the redevelopment of contaminated sites and soil improvement engineering applications.

[0041] (2) The device of the present invention has the advantage of real-time monitoring of stress field, hydraulic field, chemical field, biological field and other parameters, which is convenient for dynamic research on the uniformity and range of soil solidification at various stages during the microbial mineralization solidification process, effectively avoiding the errors and inaccuracies of manual sampling test data, and improving the convenience and operability of the test. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is a schematic diagram of the structure of the monitoring device for the bio-chemical-stress-hydraulic multi-field coupling model test used to evaluate the homogeneity of microbial mineralization;

[0043] Figure 2 Schematic diagram of the cross section of the distributed optical fiber arrangement of the monitoring device for the bio-chemical-stress-hydraulic multi-field coupled model test for evaluating the homogeneity of microbial mineralization;

[0044] Figure 3 Schematic diagram of sampling points and sensor layout of the monitoring device for the bio-chemical-stress-hydraulic multi-field coupling model test used to evaluate the homogeneity of microbial mineralization;

[0045] Description of the markings in the figure:

[0046] 1. Test model box; 2. Pressurization system; 3. Grouting system; 4. Sampling system; 5. Monitoring system; 6. Wire hole; 7. Model box; 8. Sleeve; 9. Top cover; 10. Water outlet; 11. Top cover opening; 12. Hydraulic pump; 13. Pressurization head; 14. Fixed frame; 15. Support rod; 16. Top plate; 17. Sampling tube; 18. Filter head; 19. One-way valve; 20. Distributed optical fiber sensor unit; 21. Electronic sensor unit; 22. Computer unit; 23. Grouting pump; 24. Silicone hose; 25. Grouting pipe; 26. Soft and hard pipe joints; 27. Grouting hole; 28. Sampling hole. DETAILED DESCRIPTION

[0047] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0048] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0049] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0050] In the following implementation manners or examples, unless otherwise specified, functional components or structures are conventional components or conventional structures used in the art to achieve corresponding functions.

[0051] In order to explore and evaluate the influence of overburden stress and grouting rate on the uniformity of solidified soil in a multi-field coupling environment, the present invention provides a multi-field coupling model test monitoring device for evaluating the homogeneity of microbial mineralization. Figure 1 As shown in the following, including:

[0052] A test model box 1, comprising a model box body 7 for placing a test soil body, a sleeve 8 surrounding the model box body 7, and a top cover 9 covering the test soil body;

[0053] A grouting system 3, comprising a grouting pump 23 and a grouting pipe 25 connected to the grouting outlet of the grouting pump 23, wherein the grouting pipe 25 is inserted into the test soil body along the height direction and has grouting holes 27 on the side wall for injecting grout outward;

[0054] A pressurizing system 2, comprising a pressurizing head 13 located above the top cover 9 and capable of moving up and down, wherein the pressurizing head 13 is configured to apply a preset pressure to the top cover 9;

[0055] A sampling system 4, comprising a sampling tube 17 extending from the bottom into the test soil body of the model box 7;

[0056] And a monitoring system 5, which includes a sensor component pre-placed in the test soil and used to monitor multiple field data including stress and strain, pH, conductivity, ammonium ion concentration, pore water pressure, etc.

[0057] In some specific implementations, water outlet holes 10 are distributed around the model box 7 , and a liquid storage space for storing excess slurry discharged through the water outlet holes 10 is formed between the model box 7 and the sleeve 8 .

[0058] In a more specific embodiment, filter paper is attached to the inner wall and the bottom of the model box 7, wherein the filter paper on the inner wall is used to filter the test soil, allowing only excess liquid to pass through and enter the liquid storage space between the sleeve 8 and the model box 7, while the filter paper on the bottom is mainly used to prevent the test soil from sticking and being difficult to remove.

[0059] In some specific embodiments, the model box 7 is in a cylindrical shape, exemplarily with a height of 1 m, a wall thickness of 1 cm, and an inner diameter of 2 m.

[0060] In some specific embodiments, the top cover 9 is provided with a top cover opening 11 for the grouting pipe 25 to extend into. Exemplarily, the inner diameter of the top cover opening 11 is 2.3 cm, and the top cover 9 is divided into two parts, the lower part has a diameter of 199.9 cm and a thickness of 3 cm, which is used to match the size of the inner wall of the test box to press the test soil sample, and the upper part has a diameter of 207 cm and a thickness of 2 cm, which plays a sealing role.

[0061] In some specific embodiments, the grouting system 3 also includes a silicone hose 24 and a soft and hard pipe joint 26 connected in sequence to the outlet of the grouting pump 23, and the soft and hard pipe joint 26 is also connected to the grouting pipe 25, wherein the grouting pipe 25 is used to deliver grouting slurry to the test soil.

[0062] In a more specific embodiment, filter paper is attached to the outside of the grouting pipe 25 to prevent test soil components from entering the inside of the grouting pipe 25 and affecting the grouting effect.

[0063] In a more specific embodiment, the grouting holes 27 on the side wall of the grouting pipe 25 are evenly spaced in three rows, with an interval of 120° between two rows. Exemplarily, the vertical hole spacing between two adjacent grouting holes 27 in each row of grouting holes 27 is 2 cm.

[0064] In some specific embodiments, the pressurizing system 2 further includes a fixed frame 14 and a hydraulic pump 12 . The pressurizing head 13 is disposed on the fixed frame 14 , and the hydraulic pump 12 provides power for lifting up and down.

[0065] Furthermore, the fixed frame 14 includes a support rod 15 and a top plate 16 . The support rod 15 is fixedly connected to the outer wall of the sleeve 8 . The top plate 16 is connected to the top of the support rod 15 . The pressure head 13 is arranged on the top plate 16 .

[0066] In some specific embodiments, the sampling system 4 also includes a filter head 18, a one-way valve 19 and a sampling connecting hose. The filter head 18 is arranged at one end of the sampling tube 17 extending into the test soil. The sampling connecting hose is connected to the other end of the sampling tube 17. A one-way valve 19 is also provided on the sampling connecting hose.

[0067] Exemplarily, the sampling end of the one-way valve 19 is a Luer interface, and water samples are taken through a Luer syringe; the sampling tube 17 has an outer diameter of 4 mm, a wall thickness of 1 mm, and a length of 55 cm.

[0068] In a more specific embodiment, a sampling hole 28 is also distributed at the bottom of the model box 7. After the sampling tube 17 is connected to the sampling hole 28, glass glue and rubber pads are used to seal the bottom of the sampling hole 28 to prevent leakage and loosening.

[0069] Exemplarily, for a certain size of sleeve 8 or test box, the sampling holes 28 are located at 10 cm, 30 cm, 50 cm, 70 cm, and 90 cm from the center, respectively, arranged at 60° intervals, with a total of 30 water sampling points and a hole diameter of 5 mm.

[0070] In some specific embodiments, the sensor assembly includes a distributed optical fiber sensor unit 20 and an electronic sensor unit 21, wherein the distributed optical fiber sensor unit 20 includes a stress strain sensor and is provided in a plurality of rows arranged in a vertical direction in the test soil. For example, see Figure 3 As shown, several circles can be arranged around the central axis of the test soil, each circle is provided with six, and the distance between two adjacent circles is set according to the detection requirements.

[0071] In some specific embodiments, the electronic sensor unit 21 includes a pH sensor, a conductivity sensor, an ammonium ion concentration sensor, and a pore water pressure sensor.

[0072] In some specific embodiments, each sensor in the sensor assembly is also connected to an external computer unit 22 through a wire extending from the model box 7. The computer unit 22 can receive, record and process various biological-chemical-stress-hydraulic multi-field data fed back by each sensor according to a preset program. The computer unit 22 itself does not belong to the innovative protection point of the present invention, but is a conventional device in the field, and will not be described in detail here.

[0073] The above embodiments may be implemented individually or in any combination of two or more.

[0074] The above implementation is described in more detail below in conjunction with specific examples.

[0075] Embodiment 1:

[0076] refer to Figure 1 This embodiment provides a research test device for studying the uniformity law and mechanism of microbial mineralization soil restoration under stress-hydraulic-chemical-biological multi-fields under the influence of grouting rate and overburden pressure. The model test device is used to study the solidification uniformity of heavy metal contaminated soil solidified and restored by biotechnology under the influence of different overburden pressures and different grouting rates. The model test device includes a test model box 1, a pressurization system 2, a grouting system 3, a sampling system 4, a sensor assembly and a computer unit 22.

[0077] The model test box includes a model box body 7, a sleeve 8, and a top cover 9. The model box body 7 and the sleeve 8 are centrally connected at the bottom, and the model box body 7 has holes around it for leaking excess slurry to the area between the model box body 7 and the sleeve 8. The internal area of ​​the model box body 7 is used to place the test soil for solidification. The top cover 9 has a central hole for inserting a grouting pipe 25.

[0078] The pressurizing system 2 includes a hydraulic pump 12, a pressurizing head 13, and a fixed frame 14. The fixed frame 14 includes a support rod 15 and a top plate 16. In this embodiment, there are three support rods 15 distributed at 120°, respectively connected to the outer wall of the sleeve 8, and the top ends of the support rods 15 are at the same height and connected to the top plate 16. In this embodiment, the overburden pressure is mainly adjusted by setting the hydraulic pump 12. The model of the hydraulic pump 12 is Moxin WCB, and the pressure range is 0-0.3MPa.

[0079] The grouting system 3 includes a grouting pump 23 (preferably a peristaltic pump in this embodiment), a silicone hose 24, a grouting pipe 25, and a soft and hard pipe joint 26, and each part is connected in sequence as shown. In this embodiment, the grouting rate is adjusted by setting the peristaltic pump parameters. The peristaltic pump model is Chuangrui WT600, and the flow range is 2.1-6000mL / min.

[0080] The sampling system 4 includes a sampling tube 17, a filter head 18, a one-way valve 19 (a Luer interface), and a silicone hose 24. In this embodiment, a sampling hole 28 is opened at the bottom of the sleeve 8, one end of the sampling tube 17 is connected to the filter head 18, inserted into the sampling port, and placed in the middle of the model box 7, all the sampling tubes 17 are at the same height, and the other end of the sampling tube 17 extends out of the bottom surface of the sleeve 8 and is connected to one end of the silicone hose 24, and the other end of the silicone hose 24 is connected to the one-way valve 19.

[0081] The monitoring system 5 includes an electronic sensor unit 21, including: a pH sensor (Qiju Electronics S-PH-A1LT), a conductivity sensor (Qiju Electronics S-EC-B2LT), an ammonium ion concentration sensor (Xinyangbang S-CGNF), and a pore water pressure sensor (Sienno SCYG318); a distributed optical fiber sensor includes a stress strain sensor (Yangfei YOFC-SBOA10002), and a computer unit 22, which is used to monitor pH, conductivity, ammonium ion concentration, shear wave velocity and pore water pressure in real time. A wire hole 6 is opened at the bottom of the sleeve 8, and the wires of the electronic sensor unit 21 and the distributed optical fiber sensor are connected to the computer unit 22 through the wire hole 6.

[0082] In this embodiment, the wall of the grouting pipe 25 is perforated, and the grouting holes 27 are arranged in three rows at an equal distance of 120 degrees.

[0083] In this embodiment, the sampling tube 17, the silicone hose 24, and the connection between the silicone hose 24 and the one-way valve 19 are all sealed and fixed with clamps to prevent leakage.

[0084] In this embodiment, a hole is opened in the center of the top plate 16 , and the pressure head 13 is fixedly connected to the top plate 16 by fixing screws. The top plate 16 is used to provide reaction force support for the pressure head 13 .

[0085] Example 2

[0086] Based on Example 1, this example provides a method for using the research test device for studying the uniformity law and mechanism of heavy metal contaminated soil remediation under stress-hydraulic-chemical-biological multi-fields of the traditional enhancement method, including the following steps:

[0087] Step S1: Filter paper is laid at the bottom and inside of the model box 7 to prevent soil from directly adhering to the model box 7 and to prevent soil from seeping out of the model box 7 to between the sleeve 8 and the model box 7 .

[0088] Step S2: After the sampling tube 17 and the filter head 18 are installed, the sampling hole 28 is inserted to the middle of the model box 7, the electronic sensor unit 21 is fixed close to the sampling tube 17 in the middle of the model box 7, and the distributed optical fiber sensor is pressed Figure 3 The points are arranged longitudinally in the model box 7 for detecting the parameters of the biological field, chemical field, hydraulic field and stress, and then the wires of the sensor assembly are passed through the wire holes 6, and the sampling holes 28 and the wire holes 6 are sealed with glass glue and rubber pads to prevent liquid seepage.

[0089] Step S3: Filter paper is attached to the outer wall of the grouting pipe 25 and placed in the center of the model box 7. A 20 cm thick layer of clay is laid at the bottom of the model box 7 for anti-seepage and fixing the grouting pipe 25. A thin geomembrane is laid on top of the clay and then 60 cm thick lead-contaminated soil is compacted in layers. Then, a thin geomembrane is laid on top of the lead-contaminated soil and then a 20 cm thick layer of clay is laid for anti-seepage.

[0090] Step S4: Pass the top cover 9 through the grouting pipe 25 to cover the top of the model box 7. After confirming that the fit is complete without tilt, adjust the parameters of the hydraulic pump 12 to an overburden pressure of 30 kPa, and apply the required overburden pressure to the test soil through the pressure head 13 above the top cover 9.

[0091] Step S5: The peristaltic pump, the silicone hose 24, the soft and hard pipe joint 26, and the grouting pipe 25 are connected in sequence, and the joints are sealed and fixed with clamps. Then, the peristaltic pump parameters are adjusted to a rate of 0.2 PV / h, and the exogenous bacterial solution (urea: 350 mM; ammonium chloride: 12.5 mM; sodium acetate: 42.5 mM; yeast extract: 0.1 g / L; S. pasteurii: 3.5 × 10 7 cells / mL).

[0092] Step S6: Use a Luer interface syringe to take a sample from the sampling port and perform a viable bacterial count and urea concentration determination.

[0093] Step S7: Monitor and record various test parameters of the test soil in real time through the computer unit 22.

[0094] Step S8: Inject the exogenous bacterial solution again every 24 hours, and repeat steps S6 and S7 until the pH value of each water sample stabilizes at 9.0-9.5. The injection of the exogenous bacterial solution is completed and the injection of the binder solution (urea: 350mM; ammonium chloride: 12.5mM; sodium acetate: 42.5mM; yeast extract: 0.1g / L; calcium acetate: 250mM) is started.

[0095] Step S9: Inject the cementing liquid again every 24 hours, and repeat steps S6 to S7 until the urea content is completely decomposed about 6 hours after the injection of the cementing liquid, and the consolidation is completed.

[0096] Step S10: using deionized water to rinse the solidified lead-contaminated soil to remove excess ions so as not to affect the pickling result.

[0097] Step S11: After the flushing is completed, the samples are separated and the test soil samples are placed in an oven for drying for 24 hours.

[0098] Step S12: Perform a micro cone penetration test near each sampling port of the drying test soil sample, and cut the soil sample near each sampling port to sample and use the acid washing method to determine the calcite content. When the strength of each part of the micro cone penetration test is similar, and the final calcite content of each part determined by the acid washing method is similar, it proves that the uniformity of the repair and curing is good.

[0099] Example 3

[0100] Based on Example 1, this example provides a method for using the research test device for studying the uniformity law and mechanism of heavy metal contaminated soil remediation under stress-hydraulic-chemical-biological multi-fields of the in-situ excitation method, comprising the following steps:

[0101] Step S1: Filter paper is laid at the bottom and inside of the model box 7 to prevent soil from directly adhering to the model box 7 and to prevent soil from seeping out of the model box 7 to between the sleeve 8 and the model box 7 .

[0102] Step S2: After the sampling tube 17 and the filter head 18 are installed, the sampling hole 28 is inserted to the middle of the model box 7, the electronic sensor unit 21 is fixed close to the sampling tube 17 in the middle of the model box 7, and the distributed optical fiber sensor is pressed Figure 3 The points are arranged longitudinally in the model box 7 for detecting the parameters of the biological field, chemical field, hydraulic field and stress field. Then the wires of the sensor assembly are passed through the wire hole 6, and the sampling hole 28 and the wire hole 6 are sealed with glass glue and rubber pads to prevent liquid seepage.

[0103] Step S3: Filter paper is attached to the outer wall of the grouting pipe 25 and placed in the center of the model box 7. A 20 cm thick layer of clay is laid at the bottom of the model box 7 for anti-seepage and fixing the grouting pipe 25. A thin geomembrane is laid on top of the clay and then 60 cm thick lead-contaminated soil is compacted in layers. Then, a thin geomembrane is laid on top of the lead-contaminated soil and then a 20 cm thick layer of clay is laid for anti-seepage.

[0104] Step S4: Pass the top cover 9 through the grouting pipe 25 to cover the top of the model box 7. After confirming that the fit is complete without tilt, adjust the hydraulic pump 12 to an overburden pressure of 30 kPa, and apply the required overburden pressure to the test soil by applying pressure on the top of the top cover 9 through the pressure head 13.

[0105] Step S5: Connect the peristaltic pump, silicone hose 24, soft and hard pipe joint 26, and grouting pipe 25 in sequence, seal and fix the joints with clamps, then adjust the peristaltic pump parameters to a rate of 0.2PV / h, and start injecting the stimulation solution (urea: 350mM; ammonium chloride: 12.5mM; sodium acetate: 42.5mM; yeast extract: 0.1g / L).

[0106] Step S6: Use a Luer interface syringe to take a sample from the sampling port and perform a viable bacterial count and urea concentration determination.

[0107] Step S7: Monitor and record various test parameters of the test soil in real time through the computer unit 22.

[0108] Step S8: Inject the stimulation solution again every 24 hours, and repeat steps S6 and S7 after 24 hours until the pH value of each water sample stabilizes at 9.0-9.5. The stimulation is completed, the injection of exogenous bacterial solution is completed, and the injection of the binding solution (urea: 350mM; ammonium chloride: 12.5mM; sodium acetate: 42.5mM; yeast extract: 0.1g / L; calcium acetate: 250mM) is started.

[0109] Step S9: Inject the cementing liquid again every 24 hours, and repeat steps S6 to S7 until the urea content is completely decomposed about 6 hours after the injection of the cementing liquid, and the consolidation is completed.

[0110] Step S10: using deionized water to rinse the solidified lead-contaminated soil to remove excess ions so as not to affect the pickling result.

[0111] Step S11: After the flushing is completed, the samples are separated and the test soil samples are placed in an oven for drying for 24 hours.

[0112] Step S12: Perform a micro cone penetration test near each sampling port of the drying test soil sample, and cut the soil sample near each sampling port to sample and use the acid washing method to determine the calcite content. When the strength of each part of the micro cone penetration test is similar, and the final calcite content of each part determined by the acid washing method is similar, it proves that the uniformity of the repair and curing is good.

[0113] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A multi-field coupling model test monitoring device for evaluating the homogeneity of microbial mineralization, characterized in that: include: A test model box, comprising a model box body for placing a test soil body, a sleeve surrounding the model box body, and a top cover covering the test soil body; A grouting system, comprising a grouting pump and a grouting pipe connected to the grouting outlet of the grouting pump, wherein the grouting pipe is inserted into the test soil body along a height direction and has grouting holes on its side walls for injecting grout outwards; A pressurizing system, comprising a pressurizing head located above the top cover and capable of moving up and down, the pressurizing head being configured to apply a preset pressure to the top cover; A sampling system, comprising a sampling tube extending from the bottom into the test soil body of the model box; And a monitoring system, which includes a sensor component pre-placed in the test soil and used to monitor multiple field data including stress and strain, pH, conductivity, ammonium ion concentration, pore water pressure, etc.

2. A multi-field coupling model test monitoring device for evaluating the homogeneity of microbial mineralization according to claim 1, characterized in that: Water outlet holes are distributed around the model box body, and a liquid storage space for storing excess slurry discharged through the water outlet holes is formed between the model box body and the sleeve.

3. A multi-field coupling model test monitoring device for evaluating the homogeneity of microbial mineralization according to claim 1 or 2, characterized in that: The inner wall and the bottom of the model box are both pasted with filter paper; The model box is in a cylindrical shape; The top cover is provided with a top cover opening for the grouting pipe to extend into.

4. A multi-field coupling model test monitoring device for evaluating the homogeneity of microbial mineralization according to claim 1, characterized in that: The grouting system also includes a silicone hose and a soft and hard pipe joint which are sequentially connected to the outlet of the grouting pump, and the soft and hard pipe joint is also connected to the grouting pipe, wherein the grouting pipe is used to deliver grouting slurry to the test soil.

5. A multi-field coupling model test monitoring device for evaluating the homogeneity of microbial mineralization according to claim 4, characterized in that: The outside of the grouting pipe is pasted with filter paper to prevent test soil components from entering the inside of the grouting pipe; The grouting holes on the side wall of the grouting pipe are evenly spaced and arranged in three rows.

6. A multi-field coupling model test monitoring device for evaluating the homogeneity of microbial mineralization according to claim 1, characterized in that: The pressurizing system further comprises a fixed frame and a hydraulic pump. The pressurizing head is arranged on the fixed frame, and the hydraulic pump provides power for lifting up and down.

7. A multi-field coupling model test monitoring device for evaluating the homogeneity of microbial mineralization according to claim 6, characterized in that: The fixed frame includes a support rod and a top plate, the support rod is fixedly connected to the outer wall of the sleeve, the top plate is connected to the top of the support rod, and the pressure head is arranged on the top plate.

8. A multi-field coupling model test monitoring device for evaluating the homogeneity of microbial mineralization according to claim 1, characterized in that: The sampling system also includes a filter head, a one-way valve and a sampling connecting hose. The filter head is arranged at one end of the sampling tube extending into the test soil. The sampling connecting hose is connected to the other end of the sampling tube. A one-way valve is also arranged on the sampling connecting hose.

9. A multi-field coupling model test monitoring device for evaluating the homogeneity of microbial mineralization according to claim 1, characterized in that: The sensor assembly includes a distributed optical fiber sensor unit and an electronic sensor unit, wherein the distributed optical fiber sensor unit includes a stress strain sensor and is provided in a plurality of rows arranged in a vertical direction in the test soil. The electronic sensor unit includes a pH sensor, a conductivity sensor, an ammonium ion concentration sensor, and a pore water pressure sensor; Each sensor in the sensor assembly is also connected to an external computer unit via a wire extending out of the model box.

10. A multi-field coupled model test monitoring method for evaluating the homogeneity of microbial mineralization, based on the monitoring device according to any one of claims 1 to 9, characterized in that: The monitoring method comprises the following steps: S1. Place the test soil in the model box by layered compaction, and simultaneously arrange the sampling system, grouting system, and monitoring system. After filling the test soil, cover the top cover; S2. Adjust the pressurization system to apply a preset pressure to the test soil; S3, adjusting the grouting system to perform grouting operation according to the preset grouting rate; S4. After the grouting is completed, the test soil is sampled through the sampling system and the number of viable bacteria and urea concentration are measured, and the stress-hydraulic-chemical-biological multi-field data including stress-strain, pH, conductivity, ammonium ion concentration, and pore water pressure monitored by the monitoring system are recorded in real time; S5, repeat S3 and S4 until the test soil is solidified; S6. Dry the test soil after demolition, conduct a micro cone penetration test, measure the strength of the test soil, cut and sample the soil near each sampling port, and use the acid washing method to measure the calcite content. The test is completed.

Images