A method for reinforcing magnesium oxide cement jet grouting pile combined with bilateral microbial mineralization

Abstract

This invention relates to the field of foundation waterproofing and solidification technology, and discloses a reinforcement method for magnesium oxide cement jet grouting piles combined with bilateral microbial mineralization. Magnesium oxide cement grout is injected into the weak areas between the water-stop curtains, and mineralizing bacterial solution and calcium source nutrient solution are injected sequentially into the gaps between the piles, or injected from both sides into the middle of the gaps, forming a mineralized cementitious band in the gaps. After the magnesium oxide is incorporated, it hydrates to generate magnesium hydroxide and other products, which fill the pores and, together with the cement hydration products, improve the structure of the solidified body. Simultaneously, magnesium oxide helps improve the soil microstructure, and the calcium carbonate precipitate induced by the bacterial solution further fills the pores between particles and the seepage channels, reducing porosity. The bacterial mineralization reaction occurs concentrated in the middle of the gaps between the piles, resulting in a continuous, uniform, and dense mineralized cemented band that is not concentrated in certain areas, thus avoiding pipe or nozzle blockage caused by premature reaction of the calcium source.

Description

Technical Field

[0001] This invention relates to the field of foundation waterproofing and solidification technology, and in particular to a method for reinforcement using magnesium oxide cement jet grouting piles combined with bilateral microbial mineralization. Background Technology

[0002] In the construction of deep foundation pits, underground spaces, subway stations, underground utility tunnels, municipal pipelines, water conservancy projects, and other underground engineering projects, a water-stop curtain is usually installed around the foundation pit to prevent groundwater from seeping into it. Jet grouting is a commonly used construction method for water-stop curtains. It involves high-pressure jetting of cement grout to cut through the undisturbed soil, forcibly mixing the grout with the soil to form cement-soil piles with a certain strength and impermeability. Adjacent jet grouting piles are overlapped by design to form a continuous wall-like structure, thereby achieving the function of water stoppage.

[0003] However, in actual construction, jet grouting pile water-stop curtains do not always form a completely continuous, uniform, and dense water-stop structure. Especially in sandy or silty soil strata, due to the loose soil particles, strong pore connectivity, and rapid groundwater seepage, problems such as insufficient overlap between jet grouting piles, small pile diameter, borehole deviation, unstable grouting radius, uneven grout diffusion, abnormal lifting speed, or local soil disturbance can easily lead to insufficiently cured gaps or weak interlayers between adjacent jet grouting piles.

[0004] When groundwater seeps along the weak zone between the piles, it will preferentially flow along the path with less resistance, gradually carrying away sand particles and forming seepage channels, piping channels, local voids, or erosion zones. As seepage continues, the gaps between the piles may gradually widen, leading to local failure of the cutoff wall, which in turn causes water inrush, sand inrush, ground settlement, and deformation of the support structure in the foundation pit. In severe cases, it may even cause ground subsidence outside the pit or a foundation pit collapse.

[0005] To address the aforementioned defects in jet grouting pile structures, existing remediation methods mainly include installing additional jet grouting piles, conventional cement grouting, microbial mineralization sealing, or increasing the thickness of the cutoff wall. However, these methods still have the following shortcomings: First, the construction of additional jet grouting piles causes significant disturbance, and when adding piles to areas with defects in the existing waterstop curtain, it is difficult to accurately control the reinforcement location and range.

[0006] Secondly, conventional cement grouting tends to leak along existing seepage channels, making it difficult to control the grout diffusion path and form a uniform and continuous cementitious body inside the sand pores between piles.

[0007] Third, increasing the thickness of the water-stop curtain requires increasing the cement content, increasing material consumption and carbon emissions, and the cement-soil solidified body may develop micro-cracks in the later stage due to shrinkage, groundwater erosion or wet-dry cycles.

[0008] Fourth, although microbial mineralization technology can induce calcium carbonate precipitation in the pores of sand, thereby filling the pores, cementing the sand particles, and reducing permeability, if a one-sided injection method is used, the bacterial solution or calcium source nutrient solution is prone to flow along the local high permeability channels, resulting in uneven distribution of mineralization deposition and difficulty in accurately sealing the central area of ​​the gap between piles.

[0009] Fifth, if the bacterial solution is directly mixed with cement slurry and then sprayed under high pressure, the bacteria may be affected by the high alkalinity of the cement slurry, high pressure shearing and hydration reaction, which may reduce the activity of the microorganisms and cause the pipeline or nozzle to become blocked due to the premature reaction of the calcium source.

[0010] In view of this, how to provide a composite water-stopping curtain reinforcement method that can improve the main strength of jet grouting piles, improve the pore structure of sand between piles, and enable bacterial solution and calcium source nutrient solution to meet directionally in the weak area between piles, mineralize and deposit, and gradually diffuse is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0011] The purpose of this invention is to provide a reinforcement method for magnesium oxide cement jet grouting piles combined with bilateral microbial mineralization, so as to solve the problems existing in the prior art.

[0012] To achieve the above objectives, the present invention provides a method for reinforcement of magnesium oxide cement jet grouting piles combined with bilateral microbial mineralization, comprising the following steps: S1: Two adjacent jet grouting piles form the first and second sections of the water-stopping curtain, respectively. The area between the first and second sections of the water-stopping curtain is a weak zone. S2: Drill two jet grouting drill rods into the weak area, with the drilling positions close to both sides of the weak area. Spray magnesium oxide cement grout into the weak area through the jet grouting drill rods to form the first section of jet grouting pile and the second section of jet grouting pile on both sides of the weak area. The first section of jet grouting pile is connected to the first section of water-stop curtain, and the second section of jet grouting pile is connected to the second section of water-stop curtain. S3: A gap is formed between the first and second jet grouting piles. Two grouting pipes are arranged on both sides of the gap to inject mineralizing bacteria solution and calcium source nutrient solution into the gap in sequence, or to inject mineralizing bacteria solution and calcium source nutrient solution into the middle of the gap from the left and right sides respectively, forming a mineralized cementing band in the gap. The mineralized cementing band is connected to the first and second jet grouting piles respectively.

[0013] Furthermore, the location and width of the weak zone are determined based on the design pile location, pile diameter, overlap width, and geological conditions of the jet grouting pile.

[0014] Furthermore, the magnesium oxide cement slurry is prepared by mixing water, magnesium oxide, and cement.

[0015] Furthermore, in magnesium oxide cement slurry, the mass percentage of magnesium oxide is 10%-20%.

[0016] Furthermore, the grouting pipe is provided with multiple grouting holes along the depth direction of the gap between piles.

[0017] Furthermore, in step S3, after injecting mineralizing bacterial solution into the gap between piles through the grouting pipe, the mixture is left to stand for a preset time to allow the mineralizing bacterial solution to penetrate into the middle of the gap between piles and to be adsorbed on the surface of sand particles and pore walls; after standing, calcium source nutrient solution is injected into the gap between piles through the grouting pipe.

[0018] Furthermore, in step S3, mineralizing bacterial solution is injected into the gap between piles through one grouting pipe, while calcium source nutrient solution is injected into the gap between piles through another grouting pipe.

[0019] Furthermore, the procedure also includes the following steps: after the mineralizing bacterial solution and the calcium source nutrient solution are injected simultaneously for a preset injection time, the injection medium of the injection pipe containing the mineralizing bacterial solution is replaced with the calcium source nutrient solution, and the injection medium of the injection pipe containing the calcium source nutrient solution is replaced with the mineralizing bacterial solution.

[0020] Furthermore, when the depth of the gap between piles exceeds the preset depth, mineralizing bacterial solution and calcium source nutrient solution are first injected into the lower section of the gap between piles. After a mineralized cementation zone is formed, mineralizing bacterial solution and calcium source nutrient solution are then injected into the upper section of the gap between piles.

[0021] Furthermore, when there is unidirectional seepage between piles, the grouting pressure of grouting pipes whose grouting direction is the same as or close to the seepage direction decreases, while the grouting pressure of grouting pipes whose grouting direction is opposite to or close to the seepage direction increases.

[0022] Furthermore, the upper inlet of the grouting pipe is connected to a switching valve, which can switch to a first circuit or a second circuit. The first circuit is connected to the mineralized bacterial solution grouting assembly, and the second circuit is connected to the calcium source nutrient solution grouting assembly.

[0023] The present invention discloses the following technical effects: 1. This invention uses magnesium oxide cement grout to inject grout into weak areas of the water-stop curtain. Cement hydration forms products such as hydrated calcium silicate, hydrated aluminate, and calcium hydroxide, which can cement soil particles and improve soil strength. After incorporation, magnesium oxide hydrates to generate magnesium hydroxide and other products, filling pores and improving the solidified structure together with the cement hydration products. Furthermore, magnesium oxide helps improve the soil microstructure, and the calcium carbonate precipitate induced by bacterial solution further fills the pores and seepage channels between particles. The combination of these two factors significantly reduces porosity and improves the overall impermeability of the first and second jet grouting piles and the mineralized cemented zone.

[0024] 2. In this invention, mineralizing bacterial solution and calcium source nutrient solution are injected sequentially into the gap between piles, or the mineralizing bacterial solution and calcium source nutrient solution are injected from the left and right sides into the middle of the gap between piles, thereby forming a mineralized cementing band in the gap between piles. Compared with the prior art, the mineralization reaction of the bacterial solution occurs in the middle of the gap between piles, and the mineralized cementing band is continuous, uniform, and dense, and will not be concentrated in a certain area. It can also avoid the blockage of pipelines or nozzles caused by premature reaction of calcium source.

[0025] 3. The final structure formed in the weak area by the present invention is a first section of jet grouting pile - mineralized cementing strip - second section of jet grouting pile, wherein the first and second jet grouting piles provide the main strength and rigidity, and the mineralized cementing strip fills the gaps and sand pores, which can improve the overall continuity and anti-seepage erosion ability of the water-stop curtain. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the reinforcement structure of the present invention; The components include: 1. First section of water-stop curtain; 2. Second section of water-stop curtain; 3. First section of jet grouting pile; 4. Second section of jet grouting pile; 5. Mineralized cementing strip; 6. Grouting pipe; 7. Grout tank; 8. Pressure control valve; 9. Flow meter. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] Those skilled in the art will understand that the term "comprising" as used in this application means the presence of the stated features, integers, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. It should be understood that when we say an element is "connected" or "coupled" to another element, it can be directly connected or coupled to the other element, or there may be intermediate elements present. Furthermore, "connected" or "coupled" as used herein can include wireless connections or wireless coupling. The term "and / or" as used herein includes all or any unit and all combinations of one or more associated listed items.

[0030] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0031] like Figure 1 As shown, this embodiment of the invention provides a method for reinforcing magnesium oxide cement jet grouting piles combined with bilateral microbial mineralization, comprising the following steps: S1: Two adjacent jet grouting piles form the first section of water-stop curtain 1 and the second section of water-stop curtain 2 respectively. The area between the first section of water-stop curtain 1 and the second section of water-stop curtain 2 is a weak zone. S2: Drill two jet grouting drill rods into the weak area, with the drilling positions close to both sides of the weak area. Spray magnesium oxide cement slurry into the weak area through the jet grouting drill rods to form the first section of jet grouting pile 3 and the second section of jet grouting pile 4 on both sides of the weak area. The first section of jet grouting pile 3 is connected to the first section of water-stop curtain 1, and the second section of jet grouting pile 4 is connected to the second section of water-stop curtain 2. S3: A gap is formed between the first section of jet grouting pile 3 and the second section of jet grouting pile 4. Two grouting pipes 6 are respectively arranged on both sides of the gap between the piles. They are used to inject mineralizing bacteria solution and calcium source nutrient solution into the gap between the piles in sequence, or to inject mineralizing bacteria solution and calcium source nutrient solution into the middle of the gap between the piles from the left and right sides respectively. A mineralized cementing band 5 is formed in the gap between the piles. The mineralized cementing band 5 is connected to the first section of jet grouting pile 3 and the second section of jet grouting pile 4 respectively.

[0032] In this embodiment, the grouting pipe 6 is a PVC pipe, which can be directly inserted into the formation through the borehole generated by the jet grouting drill rod, or it can be inserted into the formation through a separate drill hole. If the borehole is drilled using the jet grouting drill rod, the mineralizing bacterial solution and calcium source nutrient solution need to penetrate through part of the first section of the jet grouting pile 3 and the second section of the jet grouting pile 4. The mineralization time of the bacterial solution is slightly longer, but it does not affect the final forming effect of the mineralized cemented zone 5.

[0033] In this embodiment, based on the designed pile location, pile diameter, overlap width, drilling deviation, leakage location, and geological conditions of the jet grouting piles, weak areas where insufficient overlap or seepage channels may exist between two adjacent jet grouting piles are identified. For sandy soil, silty sand, high groundwater levels, and easily gushing sand formations, the intermediate gap area between two jet grouting piles should be considered as a weak area.

[0034] In this embodiment, the magnesium oxide cement grout is prepared by mixing water, magnesium oxide, and cement. Water-reducing agents, retarders, or dispersants are added if necessary to ensure the grout's fluidity and pumpability. The cement can be silicate cement, slag silicate cement, composite silicate cement, or other hydraulic cementitious materials; the magnesium oxide can be lightly calcined magnesium oxide, activated magnesium oxide, industrial-grade magnesium oxide, or ground magnesium oxide powder. The magnesium oxide cement grout is injected under high pressure into the target soil layer through a jet grouting drill rod, cutting, stirring, and mixing with the undisturbed soil to form the first section of jet grouting pile 3 and the second section of jet grouting pile 4 (both are magnesium oxide-modified cement-soil jet grouting piles), serving as the main structure of the water-stop curtain to provide primary strength, stiffness, and impermeability. The main functions of magnesium oxide in this invention include: reacting with water to generate hydration products such as magnesium hydroxide, which fill some of the soil pores; improving the microstructure of cement-solidified soil and increasing the compactness of the pile; working together with cement hydration products to increase the strength of the solidified soil; and improving the pore structure and resistance to seepage erosion in the edge area of ​​the jet grouting pile.

[0035] In this embodiment, the mass percentage of magnesium oxide in the magnesium oxide cement slurry is 10%-20%. According to the test results, the highest compressive strength of conventional cement slurry (without magnesium oxide) after curing is 1.28 MPa. When the magnesium oxide content is 10%, the highest compressive strength of the soil can reach 3.17 MPa. When the magnesium oxide content is 20%, the highest compressive strength of the soil can reach 6.14 MPa, indicating that magnesium oxide has a significant curing and strengthening effect on the soil.

[0036] In this embodiment, the mineralizing bacterial solution is a solution capable of inducing calcium carbonate precipitation. The microorganisms used can be *Bacillus pasteurellii*, mineralizing bacteria of the *Bacillus* genus, *Bacillus mucilaginosus*, or other microorganisms capable of inducing carbonate mineralization. After the mineralizing bacterial solution enters the inter-pile gap, the bacteria can adhere to the surface of sand particles and the pore walls, serving as nucleation sites for subsequent calcium carbonate precipitation. The mineralizing bacterial solution is injected into the inter-pile gap using a low-pressure, slow-injection method to avoid high-pressure shearing damaging the bacterial activity and to prevent the bacterial solution from rapidly flowing away along high-permeability channels. Experimental results show that the porosity of the sand decreased by up to 19.8% after the addition of magnesium oxide and the mineralizing bacterial solution, indicating that this composite system can significantly reduce the interconnected pores within the sand, thus improving its impermeability.

[0037] In this embodiment, the calcium-based nutrient solution is used to provide calcium ions and reaction substrates for microbial-induced mineralization. The calcium source can be calcium chloride, calcium acetate, calcium nitrate, calcium lactate, or other soluble calcium salts. The nutrient solution may also contain urea, ammonium salts, buffers, or other components suitable for microbial mineralization reactions.

[0038] In this embodiment, the grouting pipe 6 has multiple grouting holes arranged along the depth direction of the gap between piles.

[0039] In this embodiment, the upper inlet of the grouting pipe 6 is connected to a switching valve, which can switch to either a first circuit or a second circuit. The first circuit is connected to the mineralized bacterial solution grouting assembly, and the second circuit is connected to the calcium source nutrient solution grouting assembly. The mineralized bacterial solution grouting assembly and the calcium source nutrient solution grouting assembly have basically the same device structure, both including a grout tank 7, a pressure control valve 8, and a flow meter 9 connected in sequence. The switching valve is connected to the flow meter 9 through a connecting pipe.

[0040] There are multiple ways to inject mineralizing bacterial solution and calcium source nutrient solution. In this embodiment, after injecting mineralizing bacterial solution into the gap between piles through a grouting pipe 6, it is left to stand for a preset time to allow the mineralizing bacterial solution to penetrate into the middle of the gap between piles and be adsorbed on the surface of sand particles and pore walls. After standing, calcium source nutrient solution is injected into the gap between piles through another grouting pipe 6.

[0041] In other embodiments, after the mineralizing bacterial solution is injected into the pile gap simultaneously through two grouting pipes 6, it is left to stand for a preset time to allow the mineralizing bacterial solution to penetrate into the middle of the pile gap and be adsorbed on the surface of sand particles and pore walls. After standing, calcium source nutrient solution is injected into the pile gap simultaneously through two grouting pipes 6 to allow the mineralization reaction to occur in a larger area of ​​the pile gap.

[0042] In some embodiments, mineralizing bacterial solution is injected into the inter-pile gap through one grouting pipe 6, while calcium source nutrient solution is injected into the inter-pile gap simultaneously through another grouting pipe 6. After the mineralizing bacterial solution and calcium source nutrient solution are injected simultaneously for a preset grouting time, the grouting medium in the grouting pipe 6 injecting the mineralizing bacterial solution is replaced with calcium source nutrient solution, and the grouting medium in the grouting pipe 6 injecting the calcium source nutrient solution is replaced with mineralizing bacterial solution. This alternating grouting medium method can be repeated multiple times, allowing the mineralization reaction zone to gradually diffuse from the center of the inter-pile gap to the periphery, ultimately forming a continuous and dense mineralized cemented zone 5.

[0043] In some embodiments, when the depth of the pile gap exceeds a preset depth, mineralizing bacterial solution and calcium source nutrient solution are first injected into the lower section of the pile gap. After the mineralized cementation band 5 is formed, mineralizing bacterial solution and calcium source nutrient solution are then injected into the upper section of the pile gap.

[0044] In some embodiments, when there is unidirectional seepage in the gap between piles, the grouting pressure of the grouting pipe 6 whose grouting direction is the same as or close to the seepage direction is reduced, and the grouting pressure of the grouting pipe 6 whose grouting direction is opposite to or close to the seepage direction is increased.

[0045] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0046] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0047] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0048] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for reinforcing magnesium oxide cement jet grouting piles combined with bilateral microbial mineralization, characterized in that, Includes the following steps: S1: Two adjacent jet grouting piles form the first section of the water-stop curtain (1) and the second section of the water-stop curtain (2) respectively. The area between the first section of the water-stop curtain (1) and the second section of the water-stop curtain (2) is a weak zone. S2: Drill two jet grouting drill rods into the weak area, with the drilling positions close to both sides of the weak area. Spray magnesium oxide cement slurry into the weak area through the jet grouting drill rods to form the first section of jet grouting pile (3) and the second section of jet grouting pile (4) on both sides of the weak area. The first section of jet grouting pile (3) is connected to the first section of water-stop curtain (1), and the second section of jet grouting pile (4) is connected to the second section of water-stop curtain (2). S3: A gap is formed between the first section of jet grouting pile (3) and the second section of jet grouting pile (4). Two grouting pipes (6) are arranged on both sides of the gap between the piles to inject mineralizing bacteria solution and calcium source nutrient solution into the gap between the piles in sequence, or to inject mineralizing bacteria solution and calcium source nutrient solution into the middle of the gap between the piles from the left and right sides respectively, forming a mineralized cementing band (5) in the gap between the piles. The mineralized cementing band (5) is connected to the first section of jet grouting pile (3) and the second section of jet grouting pile (4) respectively.

2. The reinforcement method of magnesium oxide cement jet grouting piles combined with bilateral microbial mineralization according to claim 1, characterized in that, The magnesium oxide cement slurry is made by mixing water, magnesium oxide, and cement.

3. The reinforcement method for magnesium oxide cement jet grouting piles combined with bilateral microbial mineralization according to claim 2, characterized in that, In magnesium oxide cement slurry, the mass percentage of magnesium oxide is 10%-20%.

4. The reinforcement method of magnesium oxide cement jet grouting piles combined with bilateral microbial mineralization according to claim 1, characterized in that, The grouting pipe (6) has multiple grouting holes arranged along the depth direction of the gap between piles.

5. The reinforcement method of magnesium oxide cement jet grouting piles combined with bilateral microbial mineralization according to claim 1, characterized in that, In step S3, after injecting mineralizing bacterial solution into the gap between piles through the grouting pipe (6), the solution is left to stand for a preset time to allow it to penetrate into the middle of the gap between piles and to be adsorbed on the surface of sand particles and pore walls. After standing, calcium source nutrient solution is injected into the gap between piles through the grouting pipe (6).

6. The reinforcement method of magnesium oxide cement jet grouting piles combined with bilateral microbial mineralization according to claim 1, characterized in that, In step S3, mineralized bacterial solution is injected into the gap between piles through one grouting pipe (6), and calcium source nutrient solution is injected into the gap between piles through another grouting pipe (6).

7. The reinforcement method for magnesium oxide cement jet grouting piles combined with bilateral microbial mineralization according to claim 6, characterized in that, It also includes the following steps: After the mineralizing bacterial solution and calcium source nutrient solution are injected simultaneously for the preset injection time, the injection medium of the injection pipe (6) for injecting mineralizing bacterial solution is replaced with calcium source nutrient solution, and the injection medium of the injection pipe (6) for injecting calcium source nutrient solution is replaced with mineralizing bacterial solution.

8. The reinforcement method of magnesium oxide cement jet grouting piles combined with bilateral microbial mineralization according to claim 1, characterized in that, When the depth of the gap between piles exceeds the preset depth, first inject mineralizing bacteria solution and calcium source nutrient solution into the lower section of the gap between piles. After the mineralized cementation zone (5) is formed, inject mineralizing bacteria solution and calcium source nutrient solution into the upper section of the gap between piles.

9. The reinforcement method of magnesium oxide cement jet grouting piles combined with bilateral microbial mineralization according to claim 1, characterized in that, When there is unidirectional seepage in the gap between piles, the grouting pressure of the grouting pipe (6) whose grouting direction is the same as or close to the seepage direction is reduced, and the grouting pressure of the grouting pipe (6) whose grouting direction is opposite to or close to the seepage direction is increased.

10. The reinforcement method of magnesium oxide cement jet grouting piles combined with bilateral microbial mineralization according to claim 1, characterized in that, The upper inlet of the grouting pipe (6) is connected to the switching valve, which can switch to the first circuit or the second circuit. The first circuit is connected to the mineralized bacterial liquid grouting assembly, and the second circuit is connected to the calcium source nutrient solution grouting assembly.

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