Novel grouting method applied to shield wall back grouting

Abstract

The invention discloses a novel grouting method applied to shield wall back grouting, relates to the technical field of tunnel construction, and aims at solving the technical problem that a large number of raw materials need to be consumed in existing slurry preparation. The novel grouting method comprises the following steps that S1, muck is collected and transported; muck generated in the shield tunneling process is collected and transported into a ground muck pool, the integrity of the muck needs to be guaranteed in the collecting process, excessive loss or mixing of other impurities in the muck collecting and transporting process is avoided, and transporting equipment needs to have good sealing performance and stability, and pollution caused by muck leakage to the environment is prevented; s2, layout and storage of a muck pool; the muck pool is divided into at least three small muck pools, tunneled muck is stored in the first muck pool, the muck pool is divided according to the actual space and the construction process of a construction site, and it is ensured that all the small muck pools are smoothly connected. The method has the advantages that the raw material cost of the mortar is reduced, and meanwhile, the environmental pollution is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of tunnel construction, and more particularly to a novel grouting method applied to back grouting of a shield wall. Background Art

[0002] In the field of tunnel shield construction, grouting behind the wall is a key link, which plays a decisive role in the waterproof effect and settlement control of the tunnel. Its purpose is to select suitable grouting materials to ensure that the grouting behind the wall is full and dense, so as to reduce the deformation of the surrounding soil and effectively control the ground settlement. At the same time, after the slurry solidifies, it will form the first line of defense around the pipe segment, providing the tunnel with a long-term, stable and homogeneous waterproof function, which is an important measure to ensure the overall quality and service life of the tunnel.

[0003] At present, traditional shield tunneling requires synchronous grouting, and the preparation of its slurry consumes a large amount of raw materials. In addition, shield tunneling excavation will cause a large amount of slag to be discharged, and the transportation of slag requires a lot of manpower and material resources. Therefore, during the shield construction process, the cost of synchronous slurry raw materials and slag transportation accounts for a large part of the construction cost. There are a series of problems in the shield tunnel construction project, such as large amount of slurry used for grouting behind the wall, high material cost, excessive consumption of raw materials such as cement and sand, and serious environmental pollution. In view of this, we propose a new grouting method for grouting behind the shield wall. Summary of the invention

[0004] The purpose of the present invention is to provide a novel grouting method for back grouting of shield walls, so as to solve the technical problem that the configuration of existing slurry needs to consume a large amount of raw materials.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions: a new grouting method applied to rear grouting of shield wall, comprising the following steps:

[0006] S1. Collection and transportation of slag;

[0007] The debris generated during shield tunneling is collected and transported to the ground debris pool. The collection process should ensure the integrity of the debris to avoid excessive loss or mixing with other impurities during the collection and transportation process. The transportation equipment should have good sealing and stability to prevent the leakage of debris from causing environmental pollution;

[0008] S2. Layout and storage of slag pool;

[0009] Divide the slag pit into at least three small slag pits, and store the excavated slag in the first slag pit. The division of the slag pits is laid out according to the actual space and construction process of the construction site to ensure smooth connection between the small slag pits. The capacity of the first slag pit is designed according to the shield excavation speed and the amount of slag generated to ensure that it can accommodate the slag generated within at least 24 hours, and its capacity is not less than 50 cubic meters;

[0010] S3, stirring and settling once;

[0011] The excavator shall transport the slag from the first slag pit to the second slag pit as required and in quantity, and use a slurry mixer with a power of not less than 30 kilowatts in the second slag pit for the first rough mixing, and the mixing time shall be not less than 15 minutes. During the mixing process, the mixing blades of the slurry mixer shall fully cover the slag range to ensure uniform mixing. At the same time, water shall be added for the first time to mix into slurry in this step. According to the ratio of slag to water controlled between 1:0.8 and 1:1.2, an appropriate amount of water shall be added to make the slag fully moistened for easy mixing into slurry. The water addition process shall be slow and uniform to prevent local accumulation of water from affecting the mixing effect. The state of the slag shall be observed in real time during the mixing process, and the amount of water added shall be adjusted as needed. Larger debris can be precipitated in this slag pit, and the precipitation time shall be not less than 30 minutes. During the precipitation process, the slag pit shall be kept static so that the debris can be effectively precipitated to the bottom of the pit.

[0012] S4, secondary stirring and filtering step;

[0013] The upper slurry after stirring is pumped to the third slag pit by a slurry pump, and a slurry mixer with a power of not less than 30 kilowatts is used in the third slag pit for a second stirring. The stirring time is not less than 20 minutes. After the stirring is completed, a filter screen with a mesh of not less than 80 is used to filter out impurities. The filter screen should be firmly installed and easy to replace to ensure the impurity filtering effect.

[0014] Preferably, a secondary water replenishment and additive optimization is performed in this step, and an appropriate amount of water is replenished again according to the consistency of the mud and the subsequent grouting requirements, and an appropriate amount of admixture is added at the same time;

[0015] Sodium carboxymethyl cellulose is added to improve the fluidity of the mud, and the addition amount is 0.1%-0.3%;

[0016] Polyacrylamide is added to improve the stability of the mud, and the addition amount is 0.05%-0.1%;

[0017] After the admixture is added, stir again for no less than 25 minutes to ensure that the admixture is evenly dispersed in the mud, to ensure that the admixture can fully play its role, so that the mud fluidity is not less than 180 mm and the mud stratification rate does not exceed 10% after standing for 24 hours;

[0018] During the stirring and filtering process, the quality parameters of the slurry are monitored in real time, the specific gravity of the slurry is controlled between 1.2-1.3, the viscosity is controlled between 20-30 seconds, and the sand content does not exceed 5%, to ensure that it meets the subsequent grouting requirements.

[0019] Preferably, the method further comprises the following steps:

[0020] S5, slurry storage;

[0021] Pump the upper slurry after stirring in the third slag pool into a slurry storage tank with good sealing and heat preservation and a capacity of not less than 10 cubic meters for subsequent operations. During the pumping process, ensure that the flow of the slurry pump is stable and moderate to prevent slurry splashing or incomplete pumping. The pumping pipeline needs to be cleaned and maintained regularly to prevent pipeline blockage from affecting the construction progress. The flow of the slurry pump is controlled at 5-10 cubic meters / hour;

[0022] S6, adding and mixing curing agent;

[0023] Before simultaneous grouting or secondary grouting, add a certain amount of curing agent to the mud in the slurry storage tank. The mass ratio of the added amount of curing agent to the mud is 1:8-1:10. The adding method ensures that the curing agent and the mud are fully mixed and evenly mixed. Use stirring equipment to stir for no less than 10 minutes. The stirring speed is controlled at 60-100 rpm to prevent bubbles from affecting the quality of the slurry. A new slurry is formed. After the preparation of the new slurry, the performance test of fluidity and setting time is carried out in time to ensure that it meets the construction requirements;

[0024] S7, back wall grouting;

[0025] The new slurry is injected into the shield segment wall to complete the behind-the-wall grouting. During the grouting process, the grouting pressure is controlled between 0.2-0.5 MPa and the grouting speed does not exceed 15 liters / minute. At the same time, the changes in grouting pressure and segment displacement during the grouting process are monitored in real time, and the grouting parameters are adjusted in time to avoid insufficient or excessive grouting, thereby ensuring the quality and effect of the behind-the-wall grouting.

[0026] Preferably, the water content of the mud is controlled between 30% and 50% during the preparation process to ensure that the mud has an appropriate consistency, facilitate subsequent operations and stabilize the slurry properties. The added curing agent should have good curing effect and adaptability so that the mud can be cured to achieve the expected strength. The anti-seepage grade of the solidified mud material after curing is not less than P8, and the compressive strength at 28 days is not less than 15 MPa, which can effectively fill the shield gap and provide long-term stable support and waterproofing functions.

[0027] Preferably, before injecting the new slurry into the shield segment wall, the performance of the new slurry is first tested in the secondary grouting construction, and several groups of optimal mix ratios are selected to test its strength and impermeability. The length of the trial test interval is not less than 50 meters. The test process simulates actual construction conditions, including geological conditions and grouting pressure factors. The test and detection should adopt industry standard detection methods and equipment, and conduct compressive strength tests and impermeability tests to ensure that the requirements of shield construction for synchronous grouting performance are met, including that the slurry setting time is controlled between 4-6 hours, the impermeability grade is P8 under a pressure of 0.8 MPa, and the compressive strength at 7 days of age is not less than 10 MPa.

[0028] Preferably, during the entire grouting process, a complete monitoring system is provided to monitor various parameters of the slurry in real time, including but not limited to the specific gravity, viscosity, sand content, grouting pressure and grouting volume of the slurry;

[0029] Monitoring equipment is calibrated and maintained regularly to ensure the accuracy of monitoring data, and construction processes are adjusted in a timely manner based on monitoring results.

[0030] Preferably, the slag pool, slurry mixer, slurry pump and slurry storage tank are regularly maintained and serviced with a maintenance cycle not exceeding 7 days. The maintenance contents include cleaning, lubrication and component inspection and replacement of the equipment to ensure the normal operation of the equipment. Detailed operating procedures and record forms are formulated during the equipment maintenance and service process to record the maintenance status of the equipment, including maintenance time, maintenance personnel, maintenance content and information on replaced parts, to facilitate equipment management and troubleshooting.

[0031] Preferably, a detailed survey of the geological conditions in the shield construction area is conducted before construction, and the optimal mix ratio and grouting parameters of the new slurry are determined based on the geological conditions. The geological survey content includes the stratum structure, rock and soil characteristics and groundwater level. The survey method adopts a combination of drilling, geophysical exploration and in-situ testing. The drilling depth is determined based on the tunnel burial depth and stratum conditions, and shall not be less than 1.5 times the tunnel burial depth. Geophysical exploration adopts seismic wave method and resistivity method. In-situ testing includes standard penetration test and static penetration test. Combined with previous construction experience under similar geological conditions, a geological model is established, and the influence of different mix ratios and grouting parameters on the grouting effect is analyzed through numerical simulation, and finally the optimal mix ratio and grouting parameters of the new slurry suitable for the geological conditions are determined.

[0032] Preferably, a cost accounting and effect evaluation system is established during the construction process, and the costs and effects are regularly counted and analyzed so as to timely adjust the construction technology and parameters and further optimize the construction process.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] 1. The present invention utilizes the slag generated by shield tunneling as the main raw material, replacing some of the raw materials such as cement and sand required for traditional synchronous grouting slurry, thereby greatly reducing the raw material cost of mortar. Since a large amount of slag is reused within the construction site, the amount of slag transported outside is reduced, thereby reducing the consumption of manpower, material and financial resources in the slag transportation process, and solving the problem that the configuration of existing slurry requires the consumption of a large amount of raw materials.

[0035] 2. The present invention realizes the effective reuse of shield slag, reduces the occupation of land resources due to slag stacking and treatment, and the possible environmental problems such as dust pollution, which is in line with the concept of green and sustainable development. It converts the originally abandoned slag into valuable grouting materials, reduces the dependence on natural resources, and indirectly reduces the emission of greenhouse gases such as carbon dioxide in the cement production process by reducing the use of raw materials such as cement, which makes a certain contribution to alleviating the greenhouse effect. At the same time, reducing sand mining helps to protect the natural ecological environment such as riverbeds and mountains, and reduces the degree of damage to the environment.

[0036] 3. In the process of mud preparation, the present invention effectively regulates the performance of the mud by precisely controlling the mass ratio of slag and water, and performing stirring, sedimentation, filtration and adding admixtures in stages. The prepared mud has suitable water content, specific gravity, viscosity and sand content, ensuring the stability and fluidity of the slurry during stirring, transportation and grouting, and can better meet the construction requirements. The mud-state solidified material formed by adding a curing agent to the new slurry has good impermeability, compression resistance and durability, can effectively fill the shield gap, provide long-term stable support and waterproofing functions, and improve the overall quality and service life of the tunnel. DETAILED DESCRIPTION

[0037] In order to facilitate those skilled in the art to understand the technical solution of the present invention, the technical solution of the present invention is now further described.

[0038] A novel grouting method for back grouting of shield walls comprises the following steps:

[0039] S1. Collection and transportation of slag;

[0040] The debris generated during shield tunneling is collected and transported to the ground debris pool. The collection process should ensure the integrity of the debris to avoid excessive loss or mixing with other impurities during the collection and transportation process. The transportation equipment should have good sealing and stability to prevent the leakage of debris from causing environmental pollution;

[0041] S2. Layout and storage of slag pool;

[0042] Divide the slag pit into at least three small slag pits, and store the excavated slag in the first slag pit. The division of the slag pits is laid out according to the actual space and construction process of the construction site to ensure smooth connection between the small slag pits. The capacity of the first slag pit is designed according to the shield excavation speed and the amount of slag generated to ensure that it can accommodate the slag generated within at least 24 hours, and its capacity is not less than 50 cubic meters;

[0043] S3, stirring and settling once;

[0044] The excavator shall transport the slag from the first slag pit to the second slag pit as required and in quantity, and use a slurry mixer with a power of not less than 30 kilowatts in the second slag pit for the first rough mixing, and the mixing time shall be not less than 15 minutes. During the mixing process, the mixing blades of the slurry mixer shall fully cover the slag range to ensure uniform mixing. At the same time, water shall be added for the first time to mix into slurry in this step. According to the ratio of slag to water controlled between 1:0.8 and 1:1.2, an appropriate amount of water shall be added to make the slag fully moistened for easy mixing into slurry. The water addition process shall be slow and uniform to prevent local accumulation of water from affecting the mixing effect. The state of the slag shall be observed in real time during the mixing process, and the amount of water added shall be adjusted as needed. Larger debris can be precipitated in this slag pit, and the precipitation time shall be not less than 30 minutes. During the precipitation process, the slag pit shall be kept static so that the debris can be effectively precipitated to the bottom of the pit.

[0045] S4, secondary stirring and filtering step;

[0046] The upper slurry after stirring is pumped to the third slag pit by a slurry pump, and a slurry mixer with a power of not less than 30 kilowatts is used in the third slag pit for a second stirring, and the stirring time is not less than 20 minutes. After the stirring is completed, the impurities are filtered out with a filter screen of not less than 80 mesh. The filter screen should be firmly installed and easy to replace to ensure the impurity filtering effect;

[0047] In this step, the secondary water replenishment and additive optimization are carried out. According to the consistency of the mud and the subsequent grouting requirements, an appropriate amount of water is added again, and an appropriate amount of admixture is added at the same time;

[0048] Sodium carboxymethyl cellulose is added to improve the fluidity of the mud, and the addition amount is 0.1%-0.3%;

[0049] Polyacrylamide is added to improve the stability of the mud, and the addition amount is 0.05%-0.1%;

[0050] After the admixture is added, stir again for no less than 25 minutes to ensure that the admixture is evenly dispersed in the mud, to ensure that the admixture can fully play its role, so that the mud fluidity is not less than 180 mm and the mud stratification rate does not exceed 10% after standing for 24 hours;

[0051] During the stirring and filtering process, the quality parameters of the slurry are monitored in real time, and the specific gravity of the slurry is controlled between 1.2-1.3, the viscosity is controlled between 20-30 seconds, and the sand content does not exceed 5%, to ensure that it meets the subsequent grouting requirements;

[0052] S5, slurry storage;

[0053] Pump the upper slurry after stirring in the third slag pool into a slurry storage tank with good sealing and heat preservation and a capacity of not less than 10 cubic meters for subsequent operations. During the pumping process, ensure that the flow of the slurry pump is stable and moderate to prevent slurry splashing or incomplete pumping. The pumping pipeline needs to be cleaned and maintained regularly to prevent pipeline blockage from affecting the construction progress. The flow of the slurry pump is controlled at 5-10 cubic meters / hour;

[0054] S6, adding and mixing curing agent;

[0055] Before simultaneous grouting or secondary grouting, add a certain amount of curing agent to the mud in the slurry storage tank. The mass ratio of the added amount of curing agent to the mud is 1:8-1:10. The adding method ensures that the curing agent and the mud are fully mixed and evenly mixed. Use stirring equipment to stir for no less than 10 minutes. The stirring speed is controlled at 60-100 rpm to prevent bubbles from affecting the quality of the slurry. A new slurry is formed. After the preparation of the new slurry, the performance test of fluidity and setting time is carried out in time to ensure that it meets the construction requirements;

[0056] S7, back wall grouting;

[0057] The new slurry is injected into the shield segment wall to complete the behind-the-wall grouting. During the grouting process, the grouting pressure is controlled between 0.2-0.5 MPa and the grouting speed does not exceed 15 liters / minute. At the same time, the changes in grouting pressure and segment displacement during the grouting process are monitored in real time, and the grouting parameters are adjusted in time to avoid insufficient or excessive grouting, thereby ensuring the quality and effect of the behind-the-wall grouting.

[0058] In the embodiment of the present invention, the water content of the mud is controlled between 30% and 50% during the preparation process to ensure that the mud has a suitable consistency, facilitate subsequent operations and stabilize the slurry performance. The added curing agent should have a good curing effect and adaptability, so that the mud solidifies to the expected strength, and the anti-seepage grade of the solidified mud-state solidified material after curing is not less than P8, and the compressive strength at 28 days is not less than 15 MPa, which can effectively fill the shield gap and provide long-term stable support and waterproofing functions. Before the new slurry is injected into the shield segment wall, the new slurry is first grouted in the secondary grouting construction. It can carry out trial tests and select several groups of optimal mix ratios to test their strength and impermeability. The length of the trial test interval is not less than 50 meters. The test process simulates actual construction conditions, including geological conditions and grouting pressure factors. The test should adopt industry standard testing methods and equipment, and carry out compressive strength tests and impermeability tests to ensure that the requirements of shield construction for synchronous grouting performance are met, including the slurry setting time being controlled between 4-6 hours, impermeability grade P8 under a pressure of 0.8 MPa, and compressive strength of not less than 10 MPa at 7 days of age.

[0059] In the embodiment of the present invention, a complete monitoring system is provided during the entire grouting process to monitor various parameters of the slurry in real time, including but not limited to the specific gravity, viscosity, sand content, grouting pressure and grouting volume of the slurry;

[0060] The monitoring equipment shall be calibrated and maintained regularly to ensure the accuracy of the monitoring data and the construction process shall be adjusted in a timely manner according to the monitoring results;

[0061] The slag pool, slurry mixer, slurry pump and slurry storage tank are regularly maintained and serviced. The maintenance cycle does not exceed 7 days. The maintenance content includes equipment cleaning, lubrication, component inspection and replacement to ensure the normal operation of the equipment. Detailed operating procedures and record forms are formulated during equipment maintenance and service to record the maintenance status of the equipment, including maintenance time, maintenance personnel, maintenance content and replacement parts information, to facilitate equipment management and troubleshooting.

[0062] In an embodiment of the present invention, a detailed survey of the geological conditions of the shield construction area is conducted before construction, and the optimal mix ratio and grouting parameters of the new slurry are determined according to the geological conditions. The geological survey content includes the stratum structure, rock and soil characteristics and groundwater level. The survey method adopts a combination of drilling, geophysical exploration and in-situ testing. The drilling depth is determined according to the tunnel burial depth and stratum conditions, and is not less than 1.5 times the tunnel burial depth. The geophysical exploration adopts the seismic wave method and the resistivity method. The in-situ test includes the standard penetration test and the static penetration test. Combined with the previous construction experience under similar geological conditions, a geological model is established, and the influence of different mix ratios and grouting parameters on the grouting effect is analyzed through numerical simulation, and finally the optimal mix ratio and grouting parameters of the new slurry suitable for the geological conditions are determined.

[0063] In the embodiment of the present invention, a cost accounting and effect evaluation system is established during the construction process, and the cost and effect are regularly counted and analyzed so as to timely adjust the construction process and parameters and further optimize the construction process.

[0064] The embodiments of the present invention disclose preferred embodiments, but are not limited thereto. A person skilled in the art can easily understand the spirit of the present invention based on the above embodiments and make different extensions and changes. However, as long as they do not deviate from the spirit of the present invention, they are all within the protection scope of the present invention.

Claims

1. A new grouting method for back grouting of shield walls, characterized in that: The following steps are involved: S1. Collection and transportation of slag; The debris generated during shield tunneling is collected and transported to the ground debris pool. The collection process should ensure the integrity of the debris to avoid excessive loss or mixing with other impurities during the collection and transportation process. The transportation equipment should have good sealing and stability to prevent the leakage of debris from causing environmental pollution; S2. Layout and storage of slag pool; Divide the slag pit into at least three small slag pits, and store the excavated slag in the first slag pit. The division of the slag pits is laid out according to the actual space and construction process of the construction site to ensure smooth connection between the small slag pits. The capacity of the first slag pit is designed according to the shield excavation speed and the amount of slag generated to ensure that it can accommodate the slag generated within at least 24 hours, and its capacity is not less than 50 cubic meters; S3, stirring and settling once; The excavator shall transport the slag from the first slag pit to the second slag pit as required and in quantity, and use a slurry mixer with a power of not less than 30 kilowatts in the second slag pit for the first rough mixing, and the mixing time shall be not less than 15 minutes. During the mixing process, the mixing blades of the slurry mixer shall fully cover the slag range to ensure uniform mixing. At the same time, water shall be added for the first time to mix into slurry in this step. According to the ratio of slag to water controlled between 1:0.8 and 1:1.2, an appropriate amount of water shall be added to make the slag fully moistened for easy mixing into slurry. The water addition process shall be slow and uniform to prevent local accumulation of water from affecting the mixing effect. The state of the slag shall be observed in real time during the mixing process, and the amount of water added shall be adjusted as needed. Larger debris can be precipitated in this slag pit, and the precipitation time shall be not less than 30 minutes. During the precipitation process, the slag pit shall be kept static so that the debris can be effectively precipitated to the bottom of the pit. S4, secondary stirring and filtering step; The upper slurry after stirring is pumped to the third slag pit by a slurry pump, and a slurry mixer with a power of not less than 30 kilowatts is used in the third slag pit for a second stirring. The stirring time is not less than 20 minutes. After the stirring is completed, a filter screen with a mesh of not less than 80 is used to filter out impurities. The filter screen should be firmly installed and easy to replace to ensure the impurity filtering effect.

2. A novel grouting method for back grouting of shield wall according to claim 1, characterized in that: In the step S4, a secondary water replenishment and additive optimization is performed in this step, and an appropriate amount of water is replenished again according to the consistency of the mud and the subsequent grouting requirements, and an appropriate amount of admixture is added at the same time; Sodium carboxymethyl cellulose is added to improve the fluidity of the mud, and the addition amount is 0.1%-0.3%; Polyacrylamide is added to improve the stability of the mud, and the addition amount is 0.05%-0.1%; After the admixture is added, stir again for no less than 25 minutes to ensure that the admixture is evenly dispersed in the mud, to ensure that the admixture can fully play its role, so that the mud fluidity is not less than 180 mm and the mud stratification rate does not exceed 10% after standing for 24 hours; During the stirring and filtering process, the quality parameters of the slurry are monitored in real time, the specific gravity of the slurry is controlled between 1.2-1.3, the viscosity is controlled between 20-30 seconds, and the sand content does not exceed 5%, to ensure that it meets the subsequent grouting requirements.

3. A novel grouting method for back grouting of shield wall according to claim 1, characterized in that: The following steps are also included: S5, slurry storage; Pump the upper slurry after stirring in the third slag pool into a slurry storage tank with good sealing and heat preservation and a capacity of not less than 10 cubic meters for subsequent operations. During the pumping process, ensure that the flow of the slurry pump is stable and moderate to prevent slurry splashing or incomplete pumping. The pumping pipeline needs to be cleaned and maintained regularly to prevent pipeline blockage from affecting the construction progress. The flow of the slurry pump is controlled at 5-10 cubic meters / hour; S6, adding and mixing curing agent; Before simultaneous grouting or secondary grouting, add a certain amount of curing agent to the mud in the slurry storage tank. The mass ratio of the added amount of curing agent to the mud is 1:8-1:

10. The adding method ensures that the curing agent and the mud are fully mixed and evenly mixed. Use stirring equipment to stir for no less than 10 minutes. The stirring speed is controlled at 60-100 rpm to prevent bubbles from affecting the quality of the slurry. A new slurry is formed. After the preparation of the new slurry, the performance test of fluidity and setting time is carried out in time to ensure that it meets the construction requirements; S7, back wall grouting; The new slurry is injected into the shield segment wall to complete the behind-the-wall grouting. During the grouting process, the grouting pressure is controlled between 0.2-0.5 MPa and the grouting speed does not exceed 15 liters / minute. At the same time, the changes in grouting pressure and segment displacement during the grouting process are monitored in real time, and the grouting parameters are adjusted in time to avoid insufficient or excessive grouting, thereby ensuring the quality and effect of the behind-the-wall grouting.

4. A novel grouting method for back grouting of shield wall according to claim 3, characterized in that: During the preparation process of the mud, its water content is controlled between 30% and 50% to ensure that the mud has appropriate consistency, facilitate subsequent operations and stabilize the slurry performance. The added curing agent should have good curing effect and adaptability so that the mud can be cured to the expected strength. The anti-seepage grade of the solidified mud material after curing is not less than P8, and the compressive strength at 28 days is not less than 15 MPa. It can effectively fill the shield gap and provide long-term stable support and waterproofing functions.

5. A novel grouting method for back grouting of shield wall according to claim 4, characterized in that: Before injecting the new slurry into the shield segment wall, the performance of the new slurry is first tested in the secondary grouting construction, and several groups of optimal mix ratios are selected for test detection of its strength and impermeability. The length of the trial test interval is not less than 50 meters. The test process simulates the actual construction conditions, including geological conditions and grouting pressure factors. The test and detection should adopt industry standard testing methods and equipment, and carry out compressive strength tests and impermeability tests to ensure that the requirements of shield construction for synchronous grouting performance are met, including the slurry setting time being controlled between 4-6 hours, the impermeability grade P8 under a pressure of 0.8 MPa, and the compressive strength at 7 days of age is not less than 10 MPa.

6. A novel grouting method for back grouting of shield wall according to claim 5, characterized in that: During the entire grouting process, a complete monitoring system is equipped to monitor various parameters of the mud in real time, including but not limited to the specific gravity, viscosity, sand content, grouting pressure and grouting volume of the mud; Monitoring equipment is calibrated and maintained regularly to ensure the accuracy of monitoring data, and construction processes are adjusted in a timely manner based on monitoring results.

7. A novel grouting method for back grouting of shield wall according to claim 6, characterized in that: The slag pool, slurry mixer, slurry pump and slurry storage tank are regularly maintained and serviced with the maintenance cycle not exceeding 7 days. The maintenance contents include cleaning, lubrication and parts inspection and replacement of the equipment to ensure the normal operation of the equipment. Detailed operating procedures and record forms are formulated during the equipment maintenance and service process to record the maintenance status of the equipment, including maintenance time, maintenance personnel, maintenance content and replacement parts information, to facilitate equipment management and troubleshooting.

8. A novel grouting method for back grouting of shield wall according to claim 7, characterized in that: Before construction, a detailed survey of the geological conditions in the shield construction area is carried out, and the optimal mix ratio and grouting parameters of the new slurry are determined based on the geological conditions. The geological survey content includes the stratum structure, rock and soil characteristics and groundwater level. The survey method adopts a combination of drilling, geophysical exploration and in-situ testing. The drilling depth is determined according to the tunnel burial depth and stratum conditions, and shall not be less than 1.5 times the tunnel burial depth. Geophysical exploration adopts seismic wave method and resistivity method. In-situ testing includes standard penetration test and static penetration test. Combined with previous construction experience under similar geological conditions, a geological model is established, and the influence of different mix ratios and grouting parameters on the grouting effect is analyzed through numerical simulation. Finally, the optimal mix ratio and grouting parameters of the new slurry suitable for the geological conditions are determined.

9. A novel grouting method for back grouting of shield wall according to claim 8, characterized in that: Establish a cost accounting and effect evaluation system during the construction process, and regularly conduct statistics and analysis on costs and effects so as to timely adjust construction technology and parameters and further optimize the construction process.