Intelligent grouting system based on MICP and construction method

Abstract

The invention relates to the technical field of geotechnical engineering reinforcement, in particular to an intelligent grouting system based on MICP and a construction method. The grouting system comprises a stratum pre-analysis module, a dynamic grouting execution module and a real-time monitoring and feedback module. The stratum pre-analysis module performs three-dimensional permeability coefficient surveying and mapping and divides three types of treatment areas; the dynamic grouting execution module comprises segmented grouting pipes driven by an electrically-arranged sliding rail, and the segmented grouting pipes are lowered to designated coordinates through a nozzle at the interval of 5 m; and the real-time monitoring and feedback module integrates a pH sensor, an online monitoring module of a conductivity meter and a flowmeter linked with the pressure pump and is used for forming a closed-loop control loop of sensing detection, intelligent calculation and adjustment execution. The calcium ion concentration and the soil layer permeability are monitored in real time, and the grouting pressure and mode are automatically adjusted, so that the reinforcement uniformity is improved, the construction efficiency is improved, and the pipeline blockage risk is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of geotechnical engineering reinforcement, and in particular to an intelligent grouting system and construction method based on MICP. Background Art

[0002] In geotechnical reinforcement, microbial-induced calcium carbonate precipitation (MICP) technology, which uses a bacterial solution and a gelling fluid to reinforce soil, has been applied in earth-rockfill dams, slopes, and other projects. However, due to the wide variation in soil permeability, traditional MICP technology has drawbacks. Firstly, the traditional method uses gravity-fed grouting and continuous grouting, which can easily clog pipe openings with calcium carbonate deposits, resulting in inadequate deep grouting. For example, a reservoir dam required supplemental grouting due to blockage, increasing costs by 25%. Secondly, the process is not adjusted to account for variations in soil permeability. Consequently, grouting in low-permeability soils is difficult to penetrate, reducing the deep reinforcement effect by 70%. In high-permeability soils, grouting easily loses strength, resulting in only 35% of the expected reinforcement strength, and inconsistent strength and anti-seepage performance between upper and lower layers. Furthermore, the lack of real-time monitoring and control leads to delayed manual adjustments and crude fissure treatment. Due to its crude process, traditional MICP technology is difficult to adapt to complex strata, resulting in uneven reinforcement and low efficiency, impacting the stability and durability of the project. In view of this, the present application proposes an intelligent grouting system and construction method based on MICP for solving the uneven anti-seepage reinforcement caused by differences in soil permeability in traditional earth-rock dams, slopes and other projects. Summary of the Invention

[0003] The purpose of the present invention is to address the problems existing in the background technology and propose an intelligent grouting system and construction method based on MICP to solve the uneven anti-seepage reinforcement caused by differences in soil permeability in traditional earth-rock dams, slopes and other projects.

[0004] The technical solution of the present invention is: an intelligent grouting system based on MICP, the grouting system includes a formation pre-analysis module, a dynamic grouting execution module and a real-time monitoring and feedback module;

[0005] Among them, the formation pre-analysis module conducts three-dimensional permeability coefficient mapping and divides the treatment areas into three categories;

[0006] The dynamic grouting execution module includes a segmented grouting pipe driven by an electrically set slide rail, with a 5m interval as one section, which is lowered to the specified coordinates through a nozzle;

[0007] Real-time monitoring and feedback module: an online monitoring module integrating pH sensor, conductivity meter, and flow meter linked with pressure pump, used to form a closed-loop control loop of sensing detection-intelligent calculation-execution regulation; the conductivity meter is used to detect Ca 2 +Concentration.

[0008] Optionally, the stratum pre-analysis module specifically adopts the method of recommending three-dimensional mapping, drilling sampling and geological data analysis to achieve division and classification;

[0009] If the formation pre-analysis module determines that there is a permeable channel, it will increase the consistency / MICP+clay slurry filling treatment;

[0010] If the formation pre-analysis module determines that there is a permeability coefficient, the permeability coefficient is divided into three processing areas. The division criteria of the three processing areas are:

[0011] Class I area: k<1×10 -5 cm / s, Class II area: 1×10 -5 cm / s≤k≤1×10 -3 cm / s, Category III area: k>1×10 - 3 cm / s.

[0012] Optionally, the dynamic grouting execution module adopts differentiated modes for different types of treatment areas:

[0013] Category 1 area: low permeability, using high pressure permeability compensation mode;

[0014] Category II area: medium infiltration, using a small pressure balanced infiltration mode and improving the consistency of the bacterial solution;

[0015] Category III area: high permeability, improve the consistency of bacterial solution, and adopt pre-injection of bentonite slurry for mechanical interception of leakage channels.

[0016] Optionally, the control logic of the real-time monitoring and feedback module includes:

[0017] Ca was detected in the grouting fluid. 2 + If the concentration is too high, the grouting pressure will be automatically increased to relieve the blockage around the hole;

[0018] Based on the approximate distribution of formation permeability coefficients obtained from the survey and the permeability coefficient distribution calculated based on the bacterial solution consumption rate at the pressure pump location, the conversion can refer to the rock borehole water pressure test formula and interchange the permeability and soil permeability coefficient. In high permeability areas, the pressure can be reduced and the grouting time can be extended.

[0019] For low permeability soil layers, low-speed grouting is used. If the flow rate is too fast under the deadweight pressure, the consistency of the bacterial solution will be automatically increased.

[0020] For high permeability soil layers and soil layers with leakage channels, a combination of pre-injection of bentonite slurry + MICP grouting is adopted to seal both large and small pores, ultimately forming a continuous grouting curtain.

[0021] Optionally, the real-time monitoring and feedback module implements soil grouting operations through a grouting device and simultaneously monitors grouting parameters, including grouting pressure, grouting volume in each time period, grouting interval, grouting time, grouting liquid consistency, and other data;

[0022] The grouting device includes: a bacterial liquid fermentation tank with a volume of 500L, a temperature control and stirring component at 30±2℃;

[0023] Storage bin, used for mixing bacterial solution and gelling liquid;

[0024] Peristaltic pump, used for flow control, with an accuracy of ±1%;

[0025] Pressure pump, output pressure 0.1-0.5MPa, supports variable frequency adjustment;

[0026] The sliding rail has a movement accuracy of ±1mm, supports the free movement of the pressure pump on it, and supports segmented disassembly. During the segmented grouting, the pressure pump can move freely on the sliding rail and judge whether each position of the section meets the anti-seepage requirements; and after the grouting of the section is completed, the sliding rail is pulled out and the bottom grouting hole is blocked.

[0027] The present invention also proposes a construction method of an intelligent grouting system based on MICP, comprising the following steps:

[0028] Step 1: Pre-analysis of the formation: Use geological radar scanning to divide the treatment areas into three categories and determine the initial grouting strategies for different areas;

[0029] Step 2: Dynamic grouting stage: Use the slide rail to drive the grouting pipe to be lowered in sections, and monitor the Ca in real time. 2 + concentration, soil permeability, hourly bacterial liquid consumption and water level drop rate;

[0030] Step 3, intelligent adjustment stage: automatically switch the grouting pressure, grouting volume in each time period, grouting interval, grouting time, grouting liquid consistency and bacterial liquid consistency according to the monitoring data to form a closed-loop control.

[0031] Optionally, the grouting construction of the conventional soil layer in the first treatment area adopts the following process:

[0032] Bacterial solution preparation: Bacillus pasteurianus pH = 8-9, culture temperature 30℃;

[0033] Preparation of gelling solution: 1.0 mol / LCaCl 2+ 1.0 mol / L urea;

[0034] Segmented grouting: Use low-speed-intermittent mode to achieve segmented grouting, divide a grouting hole into n segments, plug each segment with clay after MIC grouting, and then proceed to the next segment grouting to ensure uniform grouting of the upper and lower segments.

[0035] Segmented grouting is used to block the lowest grouting section after the grouting of the lowest section is completed, so that the anti-seepage performance of the upper and lower sections of the grouting section can meet the requirements;

[0036] Optionally, the following process is used for grouting of soil layers with local cracks in the third treatment area:

[0037] Pre-grouting of cracks: Use a mixture of sodium bentonite, cement, and clay with a viscosity of 60 mPa·s, and grout at a pressure of 0.3 MPa until the grouting stops;

[0038] MICP main grouting: divided into 4 sections, the low permeability area uses a flow rate of 0.4m 3 / h intermittent mode, grouting each section 6 times, each time 500L mixed liquid, and intermittent time 1h.

[0039] Optionally, the grouting construction of the high fluidity soil layer of the loose sand layer in the second treatment area adopts the following technology:

[0040] Bacterial solution modification: Add 5% bentonite with a particle size of ≤50μm to increase the viscosity to 12mPa·s;

[0041] Grouting control: divided into 4 sections, stable flow rate 0.1m 3 / h, monitor the water level drop rate in real time, and increase the viscosity of the bacterial solution when it exceeds the limit.

[0042] Compared with the prior art, the present invention has the following beneficial technical effects:

[0043] The present invention divides three types of permeable areas through three-dimensional geological radar mapping, and adopts differentiated strategies such as high-pressure permeability compensation, low-pressure consistency adjustment, and bentonite pre-retention for different areas;

[0044] The real-time monitoring module of the present invention uses a pH sensor and a conductivity meter (to detect Ca 2 + concentration) and flowmeter linked to the pressure pump, forming a "detection-calculation-adjustment" second-level response mechanism, realizing dynamic feedback closed-loop control, ensuring intelligent optimization of the grouting process and self-repair of blockages;

[0045] The present invention uses electric slide rails to lower the grouting pipe in 5m sections, avoiding the waste of slurry in the whole hole section of traditional continuous grouting. The bacterial liquid consumption is reduced by 20%-25% compared with the continuous grouting mode.

[0046] The present invention implements a composite grouting strategy based on the characteristics of the seepage channel to form a continuous permeability barrier with a pore blocking rate of >90%;

[0047] In summary, the present invention uses an intelligent MICP grouting control system to monitor calcium ion concentration and soil permeability in real time, automatically adjusting the grouting pressure and mode, thereby improving reinforcement uniformity, increasing construction efficiency, and reducing the risk of pipeline blockage.

[0048] The system can save the amount of bonding materials, reduce labor requirements, has intelligent early warning and automatic construction report generation functions, can quickly adapt to different ground conditions, and truly realize efficient, accurate and economical automated foundation reinforcement. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 The flow chart of the intelligent grouting system proposed in the present invention is given;

[0050] Figure 2 The present invention provides a logic diagram for adaptively regulating grouting pressure;

[0051] Figure 3 It is a structural schematic diagram of the grouting device in the present invention;

[0052] Figure 4 Schematic diagram of adding drainage holes around the grouting holes in Example 4 of the present invention.

[0053] Reference numerals:

[0054] 1. Storage warehouse;

[0055] 2. Peristaltic pump;

[0056] 3. Flow meter;

[0057] 4. Online monitoring module;

[0058] 5. Pressure pump;

[0059] 6. Slide rail. DETAILED DESCRIPTION

[0060] The technical solutions of the present disclosure will be described clearly and completely below with reference to the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present disclosure, rather than all of the embodiments.

[0061] The components of the embodiments of the present disclosure generally described and shown in the drawings herein may be arranged and designed in a variety of different configurations. Therefore, the following detailed description of the embodiments of the present disclosure provided in the drawings is not intended to limit the scope of the claimed disclosure, but merely represents selected embodiments of the present disclosure.

[0062] Based on the embodiments of the present disclosure, all other embodiments obtained by those skilled in the art without creative work shall fall within the scope of protection of the present disclosure.

[0063] In the description of the present disclosure, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present disclosure and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on the present disclosure.

[0064] Example 1

[0065] like Figure 1-Figure 3 As shown, the present invention proposes an intelligent grouting system based on MICP, which includes a formation pre-analysis module, a dynamic grouting execution module and a real-time monitoring and feedback module;

[0066] The stratum pre-analysis module specifically adopts the method of three-dimensional mapping, borehole sampling and geological data analysis to achieve classification;

[0067] If the formation pre-analysis module determines that there is a permeable channel, it will increase the consistency / MICP+clay slurry filling treatment;

[0068] If the formation pre-analysis module determines that there is a permeability coefficient, the permeability coefficient is divided into three processing areas. The division criteria of the three processing areas are:

[0069] Class I area: k<1×10 -5 cm / s, Class II area: 1×10 -5 cm / s≤k≤1×10 -3 cm / s, Category III area: k>1×10 - 3 cm / s;

[0070] The dynamic grouting execution module includes a segmented grouting pipe driven by an electrically operated slide 6, with each section spaced 5 meters apart. The pipe is lowered to the specified coordinates by a pressure pump. Based on the permeability distribution calculated by the movement of the slide 6, the pressure pump is moved on the slide 6. The permeability coefficient at each location in the grouting section is calculated based on the water level drop rate and the bacterial solution consumption. The pressure is reduced in high-permeability areas and the grouting time is extended. Low-speed grouting is used for low-permeability soil layers. If the flow rate is too fast under the pressure of the deadweight, the bacterial solution viscosity is automatically increased. For soil layers with leakage channels, a combination of pre-injection of bentonite slurry and MICP grouting is used to block both large and small pores, ultimately forming a continuous grouting curtain.

[0071] Real-time monitoring and feedback module: integrated pH sensor, conductivity meter, online monitoring module 4 for monitoring bacterial urease activity, and flow meter 3 linked to pressure pump 5, used to form a closed-loop control loop of sensing detection-intelligent calculation-execution regulation; the conductivity meter is used to detect Ca2 + concentration; Ca was detected in the grouting fluid 2 + If the concentration is too high, the grouting pressure will be automatically increased to remove the blockage around the hole; the real-time monitoring and feedback module realizes the soil grouting operation through the grouting device, which includes: a bacterial liquid fermentation tank with a volume of 500L and a temperature control and stirring component of 30±2℃;

[0072] Storage bin 1, used for mixing bacterial liquid and gelling liquid;

[0073] Peristaltic pump 2, used for flow control, accuracy is ±1%;

[0074] Pressure pump 5, output pressure 0.1-0.5MPa, supports variable frequency adjustment;

[0075] The slide rail 6 has a moving accuracy of ±1mm, supports the pressure pump to move freely on it, and supports segmented disassembly. During the segmented grouting, the pressure pump can move freely on the slide rail 6 and judge whether each position of the section meets the anti-seepage requirements; and after the grouting of the section is completed, pull out the slide rail 6 and block the lowest grouting hole.

[0076] This embodiment implements simple MICP grouting of conventional soil layers:

[0077] Applicable conditions: homogeneous sand or silt, permeability coefficient k = 10-4 ~ 10-5 cm / s, no obvious cracks.

[0078] Steps:

[0079] 1. Preparation of bacterial solution and gelling solution:

[0080] Bacterial solution: Bacillus pasteurianus: OD600 = 1.2 ± 0.1, pH = 8.5, culture temperature 30°.

[0081] Gelling solution: 1.0 mol / LCaCl 2+ 1.0mol / L urea, water is collected on site.

[0082] 2. Sectional grouting process:

[0083] Grouting hole depth: a total of 6.0m, divided into 3 sections, each section is 2.0m, each section is grouting 6 times, each grouting is 500L of bacterial liquid and cementing liquid. After the grouting of the lowest grouting section is completed, the lowest grouting section is blocked.

[0084] Grouting method: low speed-intermittent mode, flow rate Q=0.5m 3 / d, with an interval of 5 minutes.

[0085] Real-time control: monitor the rate of water level drop and adjust the flow rate according to the water level speed.

[0086] 3. Effect verification:

[0087] Permeability coefficient after reinforcement: After grouting, wait for 5 days until the reaction is completely completed, drill holes between the grouting holes, and conduct in-situ drilling head reduction tests to measure the anti-seepage performance of the reinforced soil.

[0088] Example 2

[0089] like Figure 1-Figure 3 As shown, based on Example 1, the fissured soil layer is treated by pre-grouting clay and then MICP grouting;

[0090] Applicable conditions: There are local cracks in the soil layer, and the permeability coefficient k>10-3cm / s.

[0091] Steps:

[0092] Crack detection: Use geological radar: 200MHz antenna scanning to determine the crack location, which is in the shallow layer and close to the grouting hole.

[0093] Clay pre-grouting:

[0094] Slurry ratio: 15% sodium bentonite, 5% cement and 80% clay, with clay viscosity of 60 mPa·s.

[0095] Grouting pressure: 0.3MPa, grouting stops until grouting returns.

[0096] MICP main grouting:

[0097] Grouting control: Divide into 4 sections, intermittent mode is used in the area with lower permeability, grouting is done 6 times in each section, and 500L of bacterial liquid and cementing liquid is grouted each time.

[0098] Grouting method: low speed-intermittent mode, flow rate Q=0.5m 3 / d, with an interval of 1h.

[0099] Real-time control: monitor the rate of water level drop and adjust the flow rate according to the water level speed.

[0100] 4. Effect verification:

[0101] Permeability coefficient after reinforcement: After grouting, wait for 5 days until the reaction is completely completed, drill holes between the grouting holes, and conduct in-situ drilling head test to measure the anti-seepage performance of the reinforced soil.

[0102] Economical: It reduces the consumption of bacterial solution compared with continuous grouting.

[0103] Example 3

[0104] like Figure 1-Figure 3 As shown, based on Example 1, the bentonite MICP composite grouting is achieved;

[0105] Applicable conditions: loose sand layer, permeability coefficient k = 10 -2 ~10 -3 cm / s, and the rapid diffusion of slurry needs to be suppressed.

[0106] 1. Preparation of composite slurry:

[0107] Bacterial solution modification: Add 5% bentonite with a particle size of ≤50 μm to increase the viscosity from 1.2 mPa·s to 12 mPa·s.

[0108] Grouting process:

[0109] Grouting control: Divide into 4 sections, intermittent mode is used in the area with low permeability, Q=0.4m 3 / h, grouting for 6 times per section, with 500L of bacterial solution and cementing fluid grouting each time.

[0110] Grouting speed: stable flow rate: Q=0.1m 3 / h, to avoid turbulence leading to sedimentation and separation.

[0111] Real-time monitoring: Monitor the rate of water level drop and adjust the flow rate accordingly. If the water level drops too quickly, the bacterial solution and cementing liquid need to be re-adjusted to increase viscosity.

[0112] 4. Effect verification:

[0113] Permeability coefficient after reinforcement: After grouting, wait for 5 days for the reaction to be completely completed. Drill holes between the grouting holes to conduct in-situ drilling head test to measure the anti-seepage performance of the reinforced soil.

[0114] Example 4

[0115] like Figure 4 As shown in the figure, for soil layers with a small permeability coefficient but high anti-seepage requirements, by adding drainage holes around the grouting holes, the bacterial liquid and gelling liquid can seep and react in the soil layer, blocking the soil layer far away from the grouting holes, and finally forming a continuous grouting curtain, enhancing the conductivity to reduce the reaction time, while also enhancing the reinforcement effect.

[0116] The above specific embodiments are merely several optional embodiments of the present invention. Based on the technical solutions of the present invention and the relevant inspirations of the above embodiments, those skilled in the art may make various alternative improvements and combinations to the above specific embodiments.

Claims

1. An intelligent grouting system based on MICP, characterized in that: The grouting system includes a formation pre-analysis module, a dynamic grouting execution module and a real-time monitoring and feedback module; Among them, the formation pre-analysis module conducts three-dimensional permeability coefficient mapping and divides the treatment areas into three categories; The dynamic grouting execution module comprises a segmented grouting pipe driven by an electrically-set slide rail (6), with a 5m interval as one segment, which is lowered to a designated coordinate through a nozzle; Real-time monitoring and feedback module: an online monitoring module (4) integrating a pH sensor and a conductivity meter, and a flow meter (3) linked to a pressure pump (5), for forming a closed-loop control loop of sensing detection-intelligent calculation-execution regulation; the conductivity meter is used to detect Ca 2+ concentration.

2. The intelligent grouting system based on MICP according to claim 1, characterized in that: The stratum pre-analysis module specifically adopts the method of three-dimensional mapping, borehole sampling and geological data analysis to achieve classification; If the formation pre-analysis module determines that there is a permeable channel, it will increase the consistency / MICP+clay slurry filling treatment; If the formation pre-analysis module determines that there is a permeability coefficient, the permeability coefficient is divided into three processing areas. The division criteria of the three processing areas are: Class I area: k<1×10 -5 cm / s, Class II area: 1×10 -5 cm / s≤k≤1×10 -3 cm / s, Category III area: k>1×10 -3 cm / s.

3. The intelligent grouting system based on MICP according to claim 2, characterized in that: The dynamic grouting execution module adopts differentiated modes for different types of treatment areas: Category 1 area: low permeability, using high pressure permeability compensation mode; Category II area: medium infiltration, using a small pressure balanced infiltration mode and improving the consistency of the bacterial solution; Category III area: high permeability, improve the consistency of bacterial solution, and adopt pre-injection of bentonite slurry for mechanical interception of leakage channels.

4. The intelligent grouting system based on MICP according to claim 3, characterized in that: The control logic of the real-time monitoring and feedback module includes: Ca was detected in the grouting fluid. 2+ If the concentration is too high, the grouting pressure will be automatically increased to relieve the blockage around the hole; Based on the approximate distribution of formation permeability obtained from the survey and the permeability distribution calculated based on the bacterial solution consumption rate at the pressure pump location, the pressure in the high permeability area is reduced and the grouting time is extended; For low permeability soil layers, low-speed grouting is used. If the flow rate is too fast under the deadweight pressure, the consistency of the bacterial solution will be automatically increased. For high permeability soil layers and soil layers with leakage channels, a combination of pre-injection of bentonite slurry + MICP grouting is adopted to seal both large and small pores, ultimately forming a continuous grouting curtain.

5. The intelligent grouting system based on MICP according to claim 1, characterized in that: The real-time monitoring and feedback module realizes soil grouting operation through a grouting device, which includes: a bacterial liquid fermentation tank, a temperature control and stirring component with a volume of 500L and a temperature of 30±2℃; Storage bin (1), used for mixing bacterial liquid and gelling liquid; Peristaltic pump (2), used for flow control, with an accuracy of ±1%; Pressure pump (5), output pressure 0.1-0.5MPa, supports variable frequency adjustment; The slide rail (6) has a moving accuracy of ±1mm, supports the pressure pump to move freely on it, and supports segmented disassembly. During the segmented grouting, the pressure pump can move freely on the slide rail and judge whether each position of the segment meets the anti-seepage requirements; and after the grouting of the segment is completed, the slide rail is pulled out and the lowest grouting hole is blocked.

6. A construction method of the MICP-based intelligent grouting system according to any one of claims 1 to 5, characterized in that: The following steps are involved: Step 1: Pre-analysis of the formation: Use geological radar scanning to divide the treatment areas into three categories and determine the initial grouting strategies for different areas; Step 2, dynamic grouting stage: the grouting pipe is lowered in sections by the slide rail (6), and the Ca 2 + concentration, soil permeability and rate of water level drop; Step 3, intelligent adjustment stage: automatically switch the grouting pressure, grouting volume in each time period, grouting interval, grouting time, grouting liquid consistency and bacterial liquid consistency according to the monitoring data to form a closed-loop control.

7. The construction method of the MICP-based intelligent grouting system according to claim 6, characterized in that: The grouting construction of the conventional soil layer in the first treatment area adopts the following technology: Bacterial solution preparation: Bacillus pasteurianus pH = 8-9, culture temperature 30℃; Preparation of gelling solution: 1.0 mol / LCaCl 2+ 1.0 mol / L urea; Segmented grouting: Use low-speed-intermittent mode to achieve segmented grouting, divide a grouting hole into n segments, plug each segment with clay after MIC grouting, and then proceed to the next segment grouting to ensure uniform grouting of the upper and lower segments.

8. The construction method of the MICP-based intelligent grouting system according to claim 6, characterized in that: The following process is used for grouting of soil layers with local cracks in the third treatment area: Pre-grouting of cracks: Use a mixture of sodium bentonite, cement, and clay with a viscosity of ≈60 mPa·s, and grout at a pressure of 0.3 MPa until the grouting stops; MICP main grouting: divided into 4 sections, the low permeability area uses a flow rate of 0.4m 3 / h intermittent mode, grouting each section 6 times, each time 500L mixed liquid, and intermittent time 1h.

9. The construction method of the MICP-based intelligent grouting system according to claim 6, characterized in that: Grouting of high fluidity soil layers in loose sand layers in the second treatment area adopts the following process: Bacterial solution modification: Add 5% bentonite with a particle size of ≤50μm to increase the viscosity to 12mPa·s; Grouting control: divided into 4 sections, stable flow rate 0.1m 3 / h, monitor the water level drop rate in real time, and increase the viscosity of the bacterial solution when it exceeds the limit.

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