Microorganism reinforcement large-scale model test method and test device

Abstract

The invention discloses a microbe reinforcement large-scale model test method which comprises the following steps: step S1, assembling a test device, connecting a hollow cylinder and a base through bolts, and placing geotechnical cloth or fine-hole gauze on a bottom plate of the base; s2, the model sample is filled, and a plurality of grouting pipes are buried while filling is conducted; s3, the hollow cylinder is sealed, a plurality of grouting pipes are connected with a plurality of second ball valve switches correspondingly, and then the hollow cylinder and a top plate are connected through bolts to seal the hollow cylinder; s4, grouting reinforcement is conducted, specifically, grouting liquid in the grouting liquid barrel is extracted to conduct grouting reinforcement on the to-be-reinforced model sample in different grouting directions multiple times in a circulating mode; and S5, after grouting is completed, the test device is dismantled, and the reinforced model sample is obtained. The grouting liquid in the grout barrel is extracted to conduct multiple times of circulating grouting reinforcement in different grouting directions on the to-be-reinforced model sample, the reinforcement uniformity is improved, and the controllability of the reinforcement process is guaranteed.

Description

Technical Field

[0001] The invention relates to the technical field of microbial reinforcement, and in particular to a large-scale model test method and a test device for microbial reinforcement. Background Art

[0002] Microbial induced calcium carbonate precipitation (MICP) technology can cement loose sand / soil into a whole with a certain strength. Because of its advantages such as environmental friendliness and simple reaction mechanism, it has broad application prospects in the field of poor soil reinforcement. In the MICP test of poor soil reinforcement, the bacterial solution and the cementing solution are sequentially or mixed and then circulated into the soil to be reinforced. The bacteria decompose the urea in the cementing solution to produce carbonate ions, which react with the Ca in the solution. 2+ The calcium carbonate generated can not only fill the pores in the soil, but more importantly, it can connect the loose minerals together to form a whole, which can greatly improve the integrity of the soil and effectively improve the mechanical properties of the soil.

[0003] In addition to the bacterial activity, cementing fluid concentration, soil particle size distribution, etc. that affect the reinforcement effect of the soil, the rationality of grouting will also have a very important impact on the reinforcement effect. In the process of microbial grouting reinforcement, because the bacterial liquid or cementing fluid has good fluidity, but the existing test results show that the growth of cementing materials mainly grows along the seepage path, and the longer the seepage distance, the lower the generation amount, resulting in uncontrollable reinforcement effect and obvious uneven reinforcement.

[0004] In the existing microbial reinforcement test research, most of them are unit tests, which show strong non-uniformity of reinforcement, especially in many model tests. The existing model test device generally buries a grouting pipe in the body to be reinforced, and grouting is carried out by water pressure or self-seepage of the grouting liquid. This method often has the following problems: First, it is impossible to control the seepage direction and seepage path of the slurry, resulting in uncontrollable reinforcement effect; second, it is impossible to collect the waste liquid, which affects the next step of reinforcement, and it is impossible to achieve cyclic reinforcement, which will also have a negative impact on the environment; third, most of the grouting operations cannot be recycled after completion, resulting in a waste of resources. Summary of the invention

[0005] In view of the above problems in the prior art, the present invention provides a large-scale model test method and test device for microbial reinforcement, which solves the problem of uneven grouting reinforcement in the prior microbial reinforcement process.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] On the one hand, a large-scale model test method for microbial reinforcement is provided, which comprises the following steps:

[0008] Step S1, assembling the test device, connecting the hollow cylinder and the base by bolts, and placing geotextile or fine-mesh gauze on the bottom plate of the base;

[0009] Step S2, filling the model sample, filling the model sample to be reinforced into the hollow cylinder in layers, and burying a plurality of grouting pipes while filling in layers;

[0010] Step S3, closing the hollow cylinder, connecting the plurality of grouting pipes to the plurality of second ball valve switches respectively, and then connecting the hollow cylinder and the top plate by bolts to close the hollow cylinder;

[0011] Step S4, grouting reinforcement, connecting the hollow cylinder, the slurry bucket, the protection bucket and the vacuum pump, extracting the grouting liquid in the slurry bucket to perform grouting reinforcement in different grouting directions for multiple cycles on the model sample to be reinforced;

[0012] Step S5: After the grouting is completed, the test device is dismantled to obtain the reinforced model sample.

[0013] The hollow cylinder in the present invention is respectively connected with a slurry barrel, a protection barrel and a vacuum pump, so as to extract the grouting liquid in the slurry barrel to perform grouting reinforcement in different grouting directions for multiple cycles on the model sample to be reinforced, thereby improving the uniformity of the reinforcement and ensuring the controllability of the reinforcement process.

[0014] Furthermore, the grouting reinforcement methods in different grouting directions in step S4 include upper surface grouting method, lower surface grouting method and soil interior grouting method.

[0015] Furthermore, the upper surface grouting method includes: a first ball valve switch at the top of the hollow cylinder is connected to a slurry bucket through a pipeline, a third ball valve switch at the bottom of the hollow cylinder is connected to a fourth ball valve switch on the protection bucket through a pipeline, and a fifth ball valve switch on the protection bucket is connected to a vacuum pump through a pipeline to extract grouting liquid in the slurry bucket, so that the grouting liquid flows from top to bottom into the model specimen to be reinforced;

[0016] The lower surface grouting method includes: the third ball valve switch at the bottom of the hollow cylinder is connected to the slurry bucket through a pipeline, the first ball valve switch at the top of the hollow cylinder is connected to the fourth ball valve switch on the protection bucket through a pipeline, and the fifth ball valve switch on the protection bucket is connected to the vacuum pump through a pipeline to extract the grouting liquid in the slurry bucket, so that the grouting liquid flows from bottom to top into the model specimen to be reinforced;

[0017] The soil internal grouting method includes: the second ball valve switch at the top of the hollow cylinder is connected to the water injection end of the grouting pump through a pipeline, and the water extraction end of the grouting pump is connected to the slurry bucket; the grouting pump draws the grouting liquid in the slurry bucket, so that the grouting liquid flows into the grouting pipe through the second ball valve switch, and diffuses into the soil through the grouting holes on the grouting pipe, so that the grouting liquid flows from the inside to the outside into the model specimen to be reinforced.

[0018] On the other hand, a test device based on a large-scale model test method for microbial reinforcement is provided, which includes a test cylinder for filling the model specimen to be reinforced, a slurry barrel for holding grouting liquid, a protective barrel and a vacuum pump; the test cylinder is connected to the slurry barrel through a pipeline, the test cylinder is connected to the protective barrel through a pipeline, and the protective barrel is connected to the vacuum pump through a pipeline.

[0019] Furthermore, the test cylinder comprises a hollow cylinder, a top plate is arranged on the top of the hollow cylinder, and a base is arranged on the bottom of the hollow cylinder; the model specimen to be reinforced is filled into the hollow cylinder.

[0020] Furthermore, the base includes a bottom plate, on which a plurality of through holes are evenly opened; an inverted trapezoidal water collecting funnel is arranged at the lower end of the bottom plate; and a support column is arranged on the lower surface of the bottom plate.

[0021] Furthermore, a first ball valve switch and a plurality of second ball valve switches are arranged on the top plate, and a third ball valve switch is arranged at the lower end of the water collecting funnel;

[0022] A plurality of grouting pipes are preset in the model specimen to be reinforced, a plurality of grouting holes are evenly opened on the grouting pipes, and the plurality of grouting pipes are respectively connected with a plurality of second ball valve switches.

[0023] Furthermore, the first ball valve switch, the plurality of second ball valve switches or the third ball valve switch are respectively connected to the slurry barrel through pipelines.

[0024] Furthermore, the plurality of second ball valve switches or the third ball valve switches are connected to the fourth ball valve switch on the protection barrel through a pipeline, and the fifth ball valve switch on the protection barrel is connected to the vacuum pump through a pipeline.

[0025] Furthermore, a plurality of sixth ball valve switches are evenly arranged on the side wall of the hollow cylinder from top to bottom.

[0026] The present invention discloses a large-scale model test method and test device for microbial reinforcement, which have the following beneficial effects:

[0027] 1. The hollow cylinder in the present invention is connected with the slurry barrel, the protection barrel and the vacuum pump respectively, so as to extract the grouting liquid in the slurry barrel to carry out grouting reinforcement in different grouting directions for multiple cycles on the model specimen to be reinforced, thereby improving the uniformity of the reinforcement and ensuring the controllability of the reinforcement process.

[0028] 2. The present invention changes the injection direction of the slurry to change its seepage path, adjusts its reinforcement effect at different locations, solves the problem that the amount of cement generated in the microbial mineralization technology gradually decreases along the seepage path, improves the uniformity of reinforcement, and ensures the controllability of the reinforcement process.

[0029] 3. The hollow cylinder in the present invention is provided with ball valve switches in different directions, and the slurry bucket is connected through the ball valve switch to adjust different grouting directions, so that grouting can be carried out in three directions in a cycle, thereby improving the uniformity of reinforcement and ensuring the controllability of the reinforcement process. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The present invention is a flowchart of the use of a microbial reinforcement large-scale model test method.

[0031] Figure 2 It is a connection schematic diagram of the upper surface grouting method of the present invention.

[0032] Figure 3 It is a connection schematic diagram of the lower surface grouting method of the present invention.

[0033] Figure 4 It is a connection schematic diagram of the soil internal grouting method of the present invention.

[0034] Figure 5 It is a structural schematic diagram of the base plate of the present invention.

[0035] Figure 6 It is a structural schematic diagram of the top plate of the present invention.

[0036] Among them, 1. test cylinder; 11. hollow cylinder; 12. top plate; 13. base; 14. bottom plate; 15. through hole; 16. water collecting funnel; 17. support column; 18. grouting pipe; 19. grouting hole; 101. first ball valve switch; 102. second ball valve switch; 103. third ball valve switch; 104. sixth ball valve switch;

[0037] 2. Slurry barrel; 3. Protection barrel; 31. Fourth ball valve switch; 32. Fifth ball valve switch;

[0038] 4. Vacuum pump; 5. Grouting pump. DETAILED DESCRIPTION

[0039] The specific embodiments of the present invention are described to facilitate those skilled in the art to understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific embodiments. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, these changes are obvious, and all inventions and creations utilizing the concept of the present invention are protected.

[0040] Example 1

[0041] refer to Figure 2-Figure 6, is a structural schematic diagram of a large-scale model test device for microbial reinforcement in this embodiment, and its purpose is to solve the problem of uneven grouting reinforcement in the existing microbial reinforcement process. The test method in this embodiment will be described in detail below.

[0042] A test device based on a large-scale model test method for microbial reinforcement comprises a test cylinder 1 for filling a model sample to be reinforced, a slurry bucket 2 for containing grouting liquid, a protection bucket 3 and a vacuum pump 4.

[0043] The test cylinder 1 is connected to the slurry barrel 2 through a pipeline, the test cylinder 1 is connected to the protection barrel 3 through a pipeline, and the protection barrel 3 is connected to the vacuum pump 4 through a pipeline.

[0044] Specifically, the test cylinder 1 includes a hollow cylinder 11, a top plate 12 is provided on the top of the hollow cylinder 11, and a base 13 is provided on the bottom of the hollow cylinder 11; the model specimen to be reinforced is filled into the hollow cylinder 11. The base 13 includes a bottom plate 14, and a plurality of through holes 15 are evenly opened on the bottom plate 14; an inverted trapezoidal water collecting funnel 16 is provided at the lower end of the bottom plate 14; and a support column 17 is provided on the lower surface of the bottom plate 14.

[0045] In this embodiment, flanges are provided on the outer sides of the openings at the upper and lower ends of the hollow cylinder 11, and a flange hole that matches the upper end flange of the hollow cylinder 11 is opened on the outer circumference of the top plate 12. The hollow cylinder 11 and the top plate 12 are connected by bolts passing through the flange holes and the flanges, and a sealing strip is provided between the flange of the hollow cylinder 11 and the top plate 12, and the flange of the hollow cylinder 11 and the top plate 12 are sealed by the sealing strip.

[0046] A flange hole that matches the flange at the lower end of the hollow cylinder 11 is opened on the outer circumference of the bottom plate 14, and the hollow cylinder 11 and the bottom plate 14 are connected by bolts passing through the flange hole and the flange. A sealing strip is provided between the flange of the hollow cylinder 11 and the bottom plate 14 to seal the flange of the hollow cylinder 11 and the bottom plate 14. At the same time, a plurality of support columns 17 are evenly arranged on the outer circumference of the lower surface of the bottom plate 14 to play a supporting role.

[0047] The top plate 12, the bottom plate 14 and the water collecting funnel 16 are all made of transparent acrylic plates. The water collecting funnel 16 is bonded to the lower surface of the bottom plate 14 to form a whole. At the same time, a number of through holes 15 are evenly opened on the bottom plate 14 to connect the hollow cylinder 11 and the water collecting funnel 16, so that the waste liquid can be collected through the water collecting funnel 16, while ensuring the sealing of the equipment, and clearing the pores for the next grouting to achieve circulating grouting; secondly, grouting can also be carried out through the lower end of the water collecting funnel 16.

[0048] Specifically, a first ball valve switch 101 and multiple second ball valve switches 102 are provided on the top plate 12, and a third ball valve switch 103 is provided at the lower end of the water collecting funnel 16; multiple grouting pipes 18 are preset in the model specimen to be reinforced, and a plurality of grouting holes 19 are evenly opened on the grouting pipes 18, and the multiple grouting pipes 18 are respectively connected to the multiple second ball valve switches 102.

[0049] In this embodiment, four threaded holes are opened on the top plate 12, and a first ball valve switch 101 and three second ball valve switches 102 are installed in the threaded holes. A threaded hole is opened at the lower end of the water collecting funnel 16 for installing the third ball valve switch 103. At the same time, three grouting pipes 18 are preset in the model sample to be reinforced. The three grouting pipes 18 are pre-buried when filling the model sample to be reinforced. The grouting pipes 18 are buried in S shape to increase the contact area between the grouting pipes 18 and the model sample to be reinforced, and the end of the grouting pipe 18 is connected to the second ball valve switch 102 through a pneumatic threaded quick plug.

[0050] Specifically, the first ball valve switch 101, the plurality of second ball valve switches 102 or the third ball valve switch 103 are respectively connected to the slurry barrel 2 through pipelines. The plurality of second ball valve switches 102 or the third ball valve switch 103 are connected to the fourth ball valve switch 31 on the protection barrel 3 through pipelines, and the fifth ball valve switch 32 on the protection barrel 3 is connected to the vacuum pump 4 through pipelines.

[0051] In this embodiment, three grouting reinforcement methods, namely, upper surface grouting method, lower surface grouting method and soil internal grouting method, are used to grout the model specimen to be reinforced.

[0052] refer to Figure 2 When the upper surface grouting method is adopted, the first ball valve switch 101 at the top of the hollow cylinder 11 is connected to the slurry barrel 2 through a pipeline, the third ball valve switch 103 at the bottom of the hollow cylinder 11 is connected to the fourth ball valve switch 31 on the protective barrel 3 through a pipeline, and the fifth ball valve switch 32 on the protective barrel 3 is connected to the vacuum pump 4 through a pipeline to extract the grouting liquid in the slurry barrel 2. Due to gravity, the grouting liquid flows from top to bottom into the body to be reinforced. After a certain volume is injected, the operation is stopped, the vacuum pump 4 is turned off, and the first ball valve switch 101 is turned off; at the same time, the vacuum pump 4 can be turned on again, and the vacuum pump 4 applies negative pressure to the bottom of the model sample to be reinforced to accelerate the infiltration of the grouting liquid into the model sample to be reinforced. At this time, the seepage direction of the grouting liquid is from top to bottom into the model sample to be reinforced, and the reinforcement effect on the upper part of the model sample to be reinforced is better, but other parts are relatively poor.

[0053] refer to Figure 3When the lower surface grouting method is adopted, the third ball valve switch 103 at the bottom of the hollow cylinder 11 is connected to the slurry barrel 2 through a pipeline, the first ball valve switch 101 at the top of the hollow cylinder 11 is connected to the fourth ball valve switch 31 on the protective barrel 3 through a pipeline, and the fifth ball valve switch 32 on the protective barrel 3 is connected to the vacuum pump 4 through a pipeline to extract the grouting liquid in the slurry barrel 2. The vacuum pump 4 applies negative pressure to the upper part of the model specimen to be reinforced. Due to the air pressure, the grouting liquid flows from bottom to top into the model specimen to be reinforced. After the set volume of the grouting liquid is injected, the operation is stopped, the vacuum pump 4 is turned off, and the third ball valve switch 103 is turned off; at this time, the seepage direction of the grouting liquid is from bottom to top, and the reinforcement effect on the lower part of the model specimen to be reinforced is better.

[0054] refer to Figure 4 When the internal grouting method of the soil is adopted, the second ball valve switch 102 at the top of the hollow cylinder 11 is connected to the water injection end of the grouting pump 5 through a pipeline, and the water extraction end of the grouting pump 5 is connected to the slurry bucket 2; the grouting pump 5 extracts the grouting liquid in the slurry bucket 2, so that the grouting liquid flows into the grouting pipe 18 at a certain pressure through the second ball valve switch 102, and diffuses into the interior of the soil through the grouting holes 19 on the grouting pipe 18, so that the grouting liquid flows from the inside to the outside into the model sample to be reinforced, thereby realizing grouting inside the soil and improving the reinforcement effect inside the model sample to be reinforced.

[0055] Specifically, a plurality of sixth ball valve switches 104 are evenly arranged on the side wall of the hollow cylinder 11 from top to bottom.

[0056] In this embodiment, multiple sixth ball valve switches 104 can be used to perform real-time sampling during the grouting reinforcement process of the model sample to be reinforced.

[0057] Example 2

[0058] refer to Figure 1-Figure 6 , which is a test flow chart of a large-scale model test method for microbial reinforcement in this embodiment, and its purpose is to solve the problem of uneven grouting reinforcement in the existing microbial reinforcement process. The test method in this embodiment will be described in detail below.

[0059] A large-scale model test method for microbial reinforcement comprises the following steps:

[0060] Step S1, assembling the test device, connecting the flange at the lower end of the hollow cylinder 11 and the flange holes on the outer circumference of the bottom plate 14 of the base 13 by bolts, connecting the hollow cylinder 11 and the base 13, and placing geotextile or fine-mesh gauze on the bottom plate 14 located in the hollow cylinder 11 so as to fill the model sample to be reinforced;

[0061] Step S2, filling the model sample, filling the model sample to be reinforced into the hollow cylinder 11 in layers, and burying a plurality of grouting pipes 18 while filling in layers, burying the grouting pipes 18 in an S-shaped layout to increase the contact area between the grouting pipes 18 and the model sample to be reinforced;

[0062] Step S3, closing the hollow cylinder 11, connecting the ends of the plurality of grouting pipes 18 to the plurality of second ball valve switches 102 respectively through pneumatic threaded quick-inserts, and then passing bolts through the flange plate at the upper end of the hollow cylinder 11 and the flange holes on the outer circumference of the top plate 12 to seal and connect the closed hollow cylinder 11 and the top plate 12;

[0063] Step S4, grouting reinforcement, connecting the hollow cylinder 11, the slurry bucket 2, the protection bucket 3 and the vacuum pump 4, extracting the grouting liquid in the slurry bucket 2 to perform grouting reinforcement in different grouting directions for multiple cycles on the model sample to be reinforced;

[0064] The grouting reinforcement methods in different grouting directions in step S4 include upper surface grouting method, lower surface grouting method and soil internal grouting method.

[0065] refer to Figure 2 The upper surface grouting method includes: the first ball valve switch 101 at the top of the hollow cylinder 11 is connected to the slurry barrel 2 through a pipeline, the third ball valve switch 103 at the bottom of the hollow cylinder 11 is connected to the fourth ball valve switch 31 on the protective barrel 3 through a pipeline, and the fifth ball valve switch 32 on the protective barrel 3 is connected to the vacuum pump 4 through a pipeline to extract the grouting liquid in the slurry barrel 2. Due to gravity, the grouting liquid flows from top to bottom into the body to be reinforced. After a certain volume is injected, the operation is stopped, the vacuum pump 4 is turned off, and the first ball valve switch 101 is turned off; at the same time, the vacuum pump 4 can be turned on again, and the vacuum pump 4 applies negative pressure to the bottom of the model sample to be reinforced to accelerate the infiltration of the grouting liquid into the model sample to be reinforced. At this time, the seepage direction of the grouting liquid is from top to bottom into the model sample to be reinforced, and the reinforcement effect on the upper part of the model sample to be reinforced is better, but other parts are relatively poor.

[0066] refer to Figure 3 The lower surface grouting method includes: the third ball valve switch 103 at the bottom of the hollow cylinder 11 is connected to the slurry barrel 2 through a pipeline, the first ball valve switch 101 at the top of the hollow cylinder 11 is connected to the fourth ball valve switch 31 on the protective barrel 3 through a pipeline, and the fifth ball valve switch 32 on the protective barrel 3 is connected to the vacuum pump 4 through a pipeline to extract the grouting liquid in the slurry barrel 2. The vacuum pump 4 applies negative pressure to the upper part of the model sample to be reinforced. Due to the air pressure, the grouting liquid flows from bottom to top into the model sample to be reinforced. After the set volume of the grouting liquid is injected, the operation is stopped, the vacuum pump 4 is turned off, and the third ball valve switch 103 is turned off; at this time, the seepage direction of the grouting liquid is from bottom to top, and the reinforcement effect on the lower part of the model sample to be reinforced is better.

[0067] refer to Figure 4 When the internal grouting method of the soil is adopted, the second ball valve switch 102 at the top of the hollow cylinder 11 is connected to the water injection end of the grouting pump 5 through a pipeline, and the water extraction end of the grouting pump 5 is connected to the slurry bucket 2; the grouting pump 5 extracts the grouting liquid in the slurry bucket 2, so that the grouting liquid flows into the grouting pipe 18 at a certain pressure through the second ball valve switch 102, and diffuses into the interior of the soil through the grouting holes 19 on the grouting pipe 18, so that the grouting liquid flows from the inside to the outside into the model sample to be reinforced, thereby realizing grouting inside the soil and improving the reinforcement effect inside the model sample to be reinforced.

[0068] Step S5: After the grouting is completed, the test device is dismantled to obtain the reinforced model sample.

[0069] The three grouting methods in step S4 can be used alternately and cyclically according to actual conditions until the designed grouting reinforcement times or designed reinforcement effect are reached; after the grouting is completed, the bolts on the flanges at the upper and lower ends of the hollow cylinder 11 are opened, the top plate 12 and the bottom plate 14 are removed, and the reinforced model sample is pushed out from one end of the hollow cylinder 11. The large-scale model test of microbial reinforcement is completed, and the experimental device is still intact and can be recycled and reused.

[0070] Although the specific implementation of the invention is described in detail in conjunction with the drawings, it should not be understood as limiting the scope of protection of this patent. Within the scope described in the claims, various modifications and variations that can be made by those skilled in the art without creative work still fall within the scope of protection of this patent.

Claims

1. A large-scale model test method for microbial reinforcement, characterized in that: The following steps are involved: Step S1, assembling the test device, connecting the hollow cylinder (11) and the base (13) by bolts, and placing a geotextile or fine-mesh gauze on the bottom plate (14) of the base (11); Step S2, filling the model sample, filling the model sample to be reinforced into the hollow cylinder (11) in layers, and burying a plurality of grouting pipes (18) while filling in layers; Step S3, closing the hollow cylinder (11), connecting the plurality of grouting pipes (18) to the plurality of second ball valve switches (102) respectively, and then connecting the hollow cylinder (11) and the top plate (12) by bolts to close the hollow cylinder (11); Step S4, grouting reinforcement, connecting the hollow cylinder (11), the slurry bucket (2), the protection bucket (3) and the vacuum pump (4), extracting the grouting liquid in the slurry bucket (2) to perform grouting reinforcement in different grouting directions for multiple cycles on the model sample to be reinforced; Step S5: After the grouting is completed, the test device is dismantled to obtain the reinforced model sample.

2. The microbial reinforcement large-scale model test method according to claim 1 is characterized in that: The grouting reinforcement methods in different grouting directions in step S4 include upper surface grouting method, lower surface grouting method and soil internal grouting method.

3. The microbial reinforcement large-scale model test method according to claim 2 is characterized in that: The upper surface grouting method comprises: a first ball valve switch (101) at the top of the hollow cylinder (11) is connected to a slurry bucket (2) through a pipeline, a third ball valve switch (103) at the bottom of the hollow cylinder (11) is connected to a fourth ball valve switch (31) on a protection bucket (3) through a pipeline, and a fifth ball valve switch (32) on the protection bucket (3) is connected to a vacuum pump (4) through a pipeline to extract grouting liquid in the slurry bucket (2) so that the grouting liquid flows from top to bottom into the model specimen to be reinforced; The lower surface grouting method comprises: a third ball valve switch (103) at the bottom of the hollow cylinder (11) is connected to a slurry bucket (2) through a pipeline, a first ball valve switch (101) at the top of the hollow cylinder (11) is connected to a fourth ball valve switch (31) on a protection bucket (3) through a pipeline, and a fifth ball valve switch (32) on the protection bucket (3) is connected to a vacuum pump (4) through a pipeline to extract grouting liquid in the slurry bucket (2) so that the grouting liquid flows from bottom to top into the model specimen to be reinforced; The soil internal grouting method comprises: a second ball valve switch (102) at the top of the hollow cylinder (11) is connected to the water injection end of a grouting pump (5) through a pipeline, and the water extraction end of the grouting pump (5) is connected to a slurry bucket (2); the grouting pump (5) extracts grouting liquid in the slurry bucket (2), so that the grouting liquid flows into a grouting pipe (18) through the second ball valve switch (102), and diffuses into the soil through a grouting hole (19) on the grouting pipe (18), so that the grouting liquid flows from the inside to the outside into the model sample to be reinforced.

4. A test device based on the large-scale model test method for microbial reinforcement according to any one of claims 1 to 3, characterized in that: It comprises a test cylinder (1) for filling the model specimen to be reinforced, a slurry bucket (2) for containing grouting liquid, a protection bucket (3) and a vacuum pump (4); The test cylinder (1) is connected to the slurry barrel (2) through a pipeline, the test cylinder (1) is connected to the protection barrel (3) through a pipeline, and the protection barrel (3) is connected to the vacuum pump (4) through a pipeline.

5. The test device for the large-scale model test method of microbial reinforcement according to claim 4 is characterized by: The test cylinder (1) comprises a hollow cylinder (11), the top of the hollow cylinder (11) is provided with a top plate (12), and the bottom of the hollow cylinder (11) is provided with a base (13); the model specimen to be reinforced is filled into the hollow cylinder (11).

6. The microbial reinforcement large-scale model test device according to claim 5, characterized in that: The base (13) comprises a bottom plate (14), on which a plurality of through holes (15) are evenly arranged; an inverted trapezoidal water collecting funnel (16) is arranged at the lower end of the bottom plate (14); and a support column (17) is arranged on the lower surface of the bottom plate (14).

7. The microbial reinforcement large-scale model test device according to claim 6, characterized in that: A first ball valve switch (101) and a plurality of second ball valve switches (102) are provided on the top plate (12), and a third ball valve switch (103) is provided at the lower end of the water collecting funnel (16); A plurality of grouting pipes (18) are preset in the model specimen to be reinforced, a plurality of grouting holes (19) are evenly opened on the grouting pipes (18), and the plurality of grouting pipes (18) are respectively connected to a plurality of second ball valve switches (102).

8. The microbial reinforcement large-scale model test device according to claim 7, characterized in that: The first ball valve switch (101), the plurality of second ball valve switches (102) or the third ball valve switch (103) are respectively connected to the slurry barrel (2) through pipelines.

9. The microbial reinforcement large-scale model test device according to claim 8, characterized in that: The plurality of the second ball valve switches (102) or the third ball valve switches (103) are connected to the fourth ball valve switch (31) on the protection barrel (3) through a pipeline, and the fifth ball valve switch (32) on the protection barrel (3) is connected to the vacuum pump (4) through a pipeline.

10. The microbial reinforcement large-scale model test device according to claim 4, characterized in that: A plurality of sixth ball valve switches (104) are evenly arranged on the side wall of the hollow cylinder (11) from top to bottom.

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