Pore medium multi-sequence split lapping netting grouting control method and system

Abstract

The application discloses a kind of pore medium multi-sequence split lap netting grouting control method and system, belong to grouting engineering technical field, by carrying out multi-sequence and adjacent sequence interval setting time multi-sequence split lap netting grouting, in the interval time between every two sequences, due to the time-varying characteristics of slurry viscosity, the tip of previous sequence split slurry pulse tends to initial setting.Due to the partial initial setting of previous sequence slurry pulse, the local stress distribution changes, forcing the post-sequence split channel to occur in a new location and spread in a new direction.After passing through the influence range of the previous sequence split slurry pulse "splitting- compaction-initial setting", it returns to develop along the direction of the maximum principal stress, forming a dendritic split slurry pulse pattern in the target grouting range, which plays a mechanical reinforcement effect of splitting slurry pulse skeleton netting in the grouted medium;Avoid the disadvantage of continuous splitting channel diffusion of slurry along the direction of the maximum principal stress, only forming a limited number of main trunk split slurry pulses with a single direction.

Description

Technical Field

[0001] This invention belongs to the field of grouting engineering technology, specifically relating to a method and system for controlling grouting of porous media through multi-sequence splitting and overlapping. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] In tunnel and underground engineering construction, effectively reinforcing weak surrounding rock and other unfavorable geological formations is crucial to ensuring the safe construction of the project. Grouting technology, as a commonly used method of stratum reinforcement, can be classified into four types based on grout diffusion patterns: filling diffusion, penetration diffusion, compaction diffusion, and fracturing diffusion, each commonly found in different types of injected media.

[0004] Based on structural morphology and pore characteristics, grout can be classified into three categories: conduit media, fractured media, and porous media. 1) Conduit media refers to media with clearly continuous channels, large pore sizes, and good connectivity. Grout flows through conduits, and a filling-diffusion pattern is common. 2) Fractured media refers to media containing fracture networks within soil or rock masses. Fracture widths are typically small, with moderate connectivity. Grout flows through fractures, and a filling-permeation-diffusion pattern is common. 3) Porous media refers to media composed of tiny pores between particles. Pore sizes are typically extremely small, with poor connectivity, making grout difficult to inject. Grout often flows through permeation or even impermeable (fractured) channels, and a permeation-compaction-fractured diffusion pattern is common. According to the definition of porous media in hydrogeology, conventional porous media have pore diameters greater than 0.5 mm, while dense porous media have pore diameters less than 0.5 mm. Micropores consist of structural and secondary pores in cohesive soils.

[0005] In the existing practice of grouting reinforcement of unfavorable geological bodies, researchers and technicians have proposed some derivative control methods for grouting technology, including but not limited to:

[0006] 1) Intermittent grouting technology: This technology uses a single-component cement grout in a "grouting-setting-re-grouting" cycle. Its advantages include: it can seal wide water inflow channels within the injected medium, reducing adverse disturbances and the risk of grout loss. Its disadvantages include: the core concept of this technology is to seal flowing water channels, and it cannot achieve ground reinforcement; the single-hole grouting cycle increases the linear construction period by 2-3 times, and the sealing effect of single-component grout is poor in highly permeable formations.

[0007] 2) Pulse grouting technology: This technology stimulates pulsating permeation of grout through periodic pressure fluctuations (0.5–5 Hz). Its advantage lies in its ability to adapt to formations with different permeability coefficients (10 Hz, ... -6 ~10 -3cm / s), significantly expanding the scope of application of traditional split grouting. The disadvantage is that high-frequency pressure regulating devices are required, and the equipment failure rate is more than 30% higher than that of traditional processes, significantly increasing maintenance costs.

[0008] 3) High-pressure split grouting technology: the slurry is first split and destroyed by high pressure to form a slurry vein skeleton for reinforcement.

[0009] In tunnel and underground engineering construction, broken and weak surrounding rock such as active fault zones are often encountered. The permeability of this type of porous medium formation under high ground stress is extremely poor, and it belongs to dense porous medium formation. High-pressure split grouting is usually used for reinforcement. However, there are still some key problems to be solved in the practical application of conventional high-pressure split grouting technology, mainly in the aspect of grouting reinforcement effect:

[0010] The conventional high-pressure split grouting technology generates a split channel in the porous medium by continuous high-pressure grouting. The split channel develops preferentially along the direction of the maximum principal stress, forming a single dominant split channel, resulting in a single direction of the main split grouting vein, limited in number, and little overlap between grouting veins, making it difficult to form a main grouting vein branch and a grouting network to play a bearing role.

[0011] In addition, during the conventional high-pressure split grouting process, the slurry needs to be injected for a long time (more than 1 hour) at a large flow rate. The slurry flows along a single dominant split channel, and as the reinforcement path lengthens, the slurry pressure continues to rise, which will cause the slurry to spread over a long distance, exceeding the target reinforcement range, and even causing damage to existing support structures, ground spouting, and other unfavorable disturbances to the formation, significantly reducing the reinforcement effect and causing material waste. SUMMARY

[0012] Therefore, the present application provides a porous medium multi-order split lapping network grouting control method and system, which can solve the technical problems of continuous high-pressure grouting forming a single grouting vein, poor bearing capacity, and slurry pressure continuously increasing to exceed the target reinforcement range and damage existing support structures in the prior art.

[0013] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0014] In a first aspect, a porous medium multi-order split lapping network grouting control method is provided, in which a group of grouting holes are opened within the target grouting reinforcement range, and multi-order split grouting is performed in a single grouting hole.

[0015] During multi-order split grouting, the adjacent order split grouting is set at a certain interval of time, the slurry vein tip formed by the previous order split grouting in the direction of the maximum principal stress tends to initial setting, forcing the slurry of the subsequent order split grouting to divert and diffuse along the newly generated split channel, and then forming a grouting body containing multiple branch grouting veins.

[0016] Preferably, the grouting target reinforcement range in the pore medium is determined, and the initial split grouting pressure P 1. The initial setting time of the slurry is determined according to the initial setting time, and the grouting interval time is determined;

[0017] When the slurry pressure reaches P 1. The first-order split grout vein is formed in the direction of the maximum horizontal stress.

[0018] The grouting interval time is paused, and the second-order split grouting is performed in the same grouting hole. When the slurry pressure reaches P 2, P 2 is greater than P 1. Branches are generated on the first-order split grout vein to generate second-order split grout veins.

[0019] According to the above logic, multiple-order split grouting is performed, multiple branches are generated on the first-order split grout vein to generate multiple subsequent-order split grout veins, and the grouting body is formed.

[0020] Preferably, multiple grouting bodies are formed in the grouting target reinforcement range, and the multiple grouting bodies are overlapped to form a network in the grouting target reinforcement range.

[0021] Preferably, the grouting interval time is best in the range of 50% to 75% of the initial setting time, and the longest time is not more than 90% of the initial setting time.

[0022] Preferably, the grouting target reinforcement range and the initial split grouting pressure are obtained by analyzing the engineering geological information of the tunnel grouted stratum. The engineering geological information includes the lithology, geological structure occurrence conditions, ground stress occurrence environment, and groundwater occurrence environment of the grouted medium.

[0023] Preferably, multiple grouting holes are drilled and grouting pipes are installed before grouting. The tail end of the grouting pipe is connected to the grouting system, and a grouting recorder is installed to monitor the pressure of the grouting system and the flow of the suction port.

[0024] Preferably, each split grouting is paused after reaching the set condition.

[0025] If the slurry pressure monitored by the grouting recorder rises to the set pressure, the pressure drops instantaneously, and the drop is more than the set proportion, then the grouting is continued until the slurry pressure rises again and tends to the set pressure, and the grouting is stopped.

[0026] Preferably, the slurry is a cement-based rapid-setting slurry.

[0027] Preferably, when the slurry is a cement single-liquid slurry, the initial setting time of the cement single-liquid slurry with a rapid-setting agent is tested first, and the cement single-liquid slurry is used for grouting during each split grouting process.

[0028] When the grouting pressure rises to the set pressure, the grouting pressure appears a transient drop and the drop amplitude exceeds the set proportion, the accelerating agent is added in the cement single slurry, and then the grouting is continuously carried out until the slurry pressure rises again and tends to the set pressure, and the grouting is stopped.

[0029] Preferably, when the secondary-order splitting grouting is carried out, the slurry in the grouting pipe is a complete fluid-phase slurry, the tip of the first-order splitting slurry vein is a complete solid-phase slurry vein, the middle part is a fluid-solid mixed slurry, and the tail end is a complete fluid-phase slurry. The pore medium in the range of the tip of the first-order splitting slurry vein is completely squeezed by the complete solid-phase slurry vein.

[0030] Preferably, the slurry of the secondary-order splitting grouting is diverted in the fluid-solid mixed slurry of the first-order splitting slurry vein, bypasses the pore medium squeezed by the first-order splitting slurry vein, and then returns to the direction of the maximum principal stress to form the secondary-order splitting slurry vein.

[0031] Preferably, when the post-order splitting grouting is carried out after the secondary-order splitting grouting, the slurry in the grouting pipe is still a complete fluid-phase slurry. The diversion point of the post-order splitting grouting is closer to the grouting pipe than the diversion point of the secondary-order splitting grouting. The slurry of the post-order splitting grouting is diverted in the direction in which the secondary-order splitting slurry vein is not filled to form the post-order splitting slurry vein.

[0032] The second aspect provides a pore medium multi-order splitting and lapping network grouting control system, which comprises a grouting module. The grouting module is configured to open grouting group holes in a grouting target reinforcement range and carry out multi-order splitting grouting in single grouting holes.

[0033] When the multi-order splitting grouting is carried out, the adjacent order splitting grouting is separated by a set time. The tip of the slurry vein formed by the previous order splitting grouting in the direction of the maximum principal stress tends to initial setting, so that the slurry of the post-order splitting grouting is diverted and diffused along the newly generated splitting channel to form a grouting body containing multi-branch slurry veins.

[0034] Preferably, the system comprises an analysis module. The analysis module is configured to determine the grouting target reinforcement range in the pore medium, the initial splitting grouting pressure, the initial setting time of the slurry, and the grouting interval time. P 1. The initial setting time of the slurry, which is used to determine the grouting interval time.

[0035] The grouting module comprises a grouting system and a grouting recorder. The grouting recorder monitors the slurry pressure of the grouting system. When the first-order splitting grouting is carried out, the grouting is paused when the slurry pressure reaches P 1. The slurry forms the first-order splitting slurry vein in the direction of the maximum horizontal stress.

[0036] The grouting is paused for a certain interval time. The secondary-order splitting grouting is carried out in the same grouting hole. The grouting is paused when the slurry pressure reaches P 2, P 2 is greater than P1, on the first order splitting vein, branch generation, generate secondary order splitting vein;

[0037] According to the above logic, multiple order splitting grouting is carried out, and multiple branches are generated on the first order splitting vein to generate multiple secondary order splitting veins, which jointly form a grouting body.

[0038] Preferably, in the grouting target reinforcement range, multiple grouting bodies are formed by multiple order splitting grouting construction, and the multiple grouting bodies are lapped into a network in the grouting target reinforcement range.

[0039] Preferably, if the grout pressure monitored by the grouting recorder rises to the splitting pressure and then instantaneously drops, and the drop amplitude exceeds the set proportion, then continuous grouting is carried out until the grout pressure rises again and tends to the splitting pressure, and the grouting is stopped.

[0040] In a third aspect, a control terminal is provided, comprising a processor and a memory, the processor being used to implement instructions; the memory is used to store a plurality of instructions, the instructions are suitable for being loaded and executed by the processor to implement the pore medium multi-order splitting lapping network grouting control method.

[0041] Compared with the prior art, the present application has the advantages and positive effects that:

[0042] The grouting control method of the present application sets a time interval between adjacent order splitting grouting, uses the time-varying characteristics of grout viscosity, makes the tip of the previous order splitting vein tend to initial setting, changes the local stress distribution, and temporarily blocks the previous order splitting channel, forces the grout of the subsequent order splitting grouting to turn around, diffuse along the newly generated splitting channel, bypass the influence range of the "splitting- compaction- initial setting" of the previous order splitting vein, and return to the development direction of the maximum principal stress to generate the subsequent order splitting vein; in single-hole grouting, by changing the splitting position and diffusion direction of each order splitting grouting, a grouting body containing multiple branch splitting veins is formed, and then through group-hole multi-order splitting grouting, the branch veins of multiple grouting bodies are lapped into a network to form a "splitting vein network, mutual lapping between grouting bodies" bearing framework in the target grouting reinforcement range, and high-efficiency reinforcement is realized. Avoid the disadvantageous reinforcement situation that the grout always diffuses along the dominant splitting channel of the maximum principal stress, and only a limited number of main splitting veins in a single direction are formed.

[0043] The adjacent order split grouting interval setting time of the application utilizes the time-varying characteristics of the slurry viscosity, so that the tip of the previous order split slurry vein tends to initial setting, and the previous order split channel is temporarily blocked, which can avoid the long-distance diffusion of the split slurry along a single dominant split channel, resulting in exceeding the grouting reinforcement range and causing waste of slurry material; at the same time, it can also avoid the high pressure in the slurry being transmitted to the deep surrounding rock along a single and long-distance split channel, resulting in adverse disturbance of the surrounding rock, and even opening a new water gushing channel in a water-rich environment; the grouting pressure of the application is gradually increased, which can also reduce the disturbance to the stratum or the existing supporting structure compared with the high pressure growth of the continuous grouting in the prior art; the grouting range of each order split slurry vein of the application does not exceed the grouting reinforcement range, so the path of the slurry is relatively shorter than the single split channel of the high pressure grouting in the prior art, and the pressure of the final order split grouting is lower than the termination pressure of the high pressure grouting in the prior art, which can avoid the high pressure in the slurry being too high to cause adverse effects on the existing tunnel supporting structure, causing major safety construction accidents such as deformation of surrounding rock, compression and distortion failure of arch support, and upheaval of inverted arch. BRIEF DESCRIPTION OF DRAWINGS

[0044] The drawings accompanying the specification of this application form a part thereof, serve to provide further understanding of the application, and together with the description of the exemplary embodiments of the application and explanations thereof serve to explain the application, and do not constitute an improper limitation of the application.

[0045] Figure 1 is a flow chart of S1 in the control method of embodiment 1 of the application;

[0046] Figure 2 is a flow chart of S2 in the control method of embodiment 1 of the application;

[0047] Figure 3 is a flow chart of S3 in the control method of embodiment 1 of the application;

[0048] Figure 4 is a grouting implementation schematic diagram in the grouting target reinforcement range of embodiment 1 or embodiment 2 of the application;

[0049] Figure 5 is a schematic diagram of the grouting body and the slurry vein fluid-solid phase of the grouting body of embodiment 1 or embodiment 2 of the application;

[0050] Figure 6 is a schematic diagram of the grouting pressure-time (P-t) curve of the temporary suspension grouting of embodiment 1 of the application;

[0051] Figure 7 is a schematic diagram of the grouting pressure-time (P-t) curve of the adjustment of the slurry of embodiment 1 of the application;

[0052] Figure 8 is a schematic diagram of the traditional split grouting diffusion mechanism in the prior art;

[0053] Figure 9 is a schematic diagram of the mechanism of multi-branch grout diffusion produced by multi-order split lapping network grouting of the embodiment 1 of the present application;

[0054] Figure 10 is a local schematic diagram of the diffusion in a new position and in a new direction by secondary-order split grouting of the embodiment 1 of the present application;

[0055] in the figure:

[0056] 1, pore medium; 2, multi-order split lapping network grouting pore medium; 3, local multi-order split lapping network grouting pore medium; 4, complete fluid phase grout; 5, complete solid phase grout; 6, mixed fluid-solid phase grout; 7, first-order split channel; 8, new position and new direction of secondary-order split diffusion; 9, secondary-order split channel; 10, first-order split grout; 11, secondary-order split grout; 12, third (or multi-) order split grout; 13, maximum horizontal ground stress (σ h ); 14, vertical ground stress (σ v ); 15, horizontal stress change (Δσ h ) caused by the initial solid phase grout; 16, vertical stress change (Δσ v ) caused by the initial solid phase grout; 17, grouting pipe; 18, grout stopping wall; 19, grouting body; 20, orifice compaction grout package; 21, fluid phase-solid phase schematic strip of grout; 22, fluid phase split grout; 23, solid phase split grout; 24, tunnel; 25, grouting system; 26, grouting target reinforcement range; 27, grouted stratum. DETAILED DESCRIPTION

[0057] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0058] The present application will be described in detail below with reference to the accompanying drawings.

[0059] Embodiment 1

[0060] The control method for multi-order split lapping network grouting of a pore medium disclosed in this embodiment is based on the rheological characteristics of cement-based grout, fully considers the phase change characteristics of the grout, and forms a grouting body with multiple grout veins by implementing a grouting method with multiple orders, different grouting times, and pressure increment in stages, and is particularly suitable for dense pore media with poor permeability.

[0061] In the embodiment, a group of grouting holes (including a plurality of single grouting holes) are arranged in the grouting target reinforcement range of the tunnel excavation face (such as the grouting target reinforcement range of the advanced curtain grouting), and multi-order splitting grouting is carried out in the single grouting hole. In some other embodiments, a group of grouting holes can also be arranged in the grouting target reinforcement range in the roadway, and then multi-order splitting grouting is carried out. Therefore, the scheme is not limited to tunnel construction.

[0062] When multi-order splitting grouting is carried out in a single hole, the adjacent multi-order splitting grouting is spaced apart by a set time, the slurry viscosity time-varying characteristics are used, the slurry pulse tip formed by the previous order splitting grouting in the maximum principal stress direction tends to initial setting, the stress distribution of the adjacent pore medium is changed, and the previous order splitting channel is temporarily blocked, so that the slurry of the subsequent order splitting grouting is diverted and diffuses along the newly generated splitting channel. After the influence range of the previous order splitting slurry around the pore medium stress distribution is bypassed, the slurry continues to develop in the maximum principal stress direction, the diffusion direction of the splitting slurry is enriched, and then the grouting body containing a plurality of branch slurry pulses is formed.

[0063] By changing the splitting position and diffusion direction of each order splitting grouting, the disadvantageous reinforcement condition that the slurry always diffuses along the dominant splitting channel in the maximum principal stress direction and only a limited number of main trunk splitting slurry pulses in a single direction are formed is avoided.

[0064] Multi-order splitting grouting is carried out in the group of grouting holes, the slurry pulses are branched and lapped into a network, and a bearing framework of "splitting slurry pulse network and mutual lapping of grouting bodies" is formed in the grouting target reinforcement range.

[0065] As shown in Figure 1 , Figure 2 , Figure 3 A pore medium multi-order splitting lapping network grouting control method, comprising the following specific steps:

[0066] S1, grouting design; specifically, the engineering geological information (such as: the lithology of the grouted medium, the stress condition of the occurrence place, the underground water environment, etc.) of the tunnel 24 in the grouted stratum 27 is analyzed, the grouting target reinforcement range 26 in the pore medium, the initial splitting grouting pressure, and the grouting wall 18 with a set thickness are determined; then the grouting slurry (i.e. grouting material) and the grouting system 25 are selected, and the grouting slurry is tested for initial setting time t c , the grouting interval time is determined according to the initial setting time t c ; the grouting system and the grouting pipe are calibrated, and the operation performance of the grouting system is tested.

[0067] S11. Analyze engineering geological information, including the lithology of the injected medium in the injected stratum 27, geological structure occurrence conditions, the occurrence environment of the injected medium's in-situ stress (in-situ stress refers to triaxial in-situ stress), and the groundwater occurrence environment.

[0068] First, the lithology of the injected medium in the injected stratum 27 is analyzed, specifically including the parent rock properties, particle size, permeability, compressive and shear strength properties, etc.; the grouting diffusion mode is selected according to the characteristics of the injected medium. When the injected medium has high permeability, permeation diffusion grouting can be used; when the injected medium has low permeability and is extremely difficult to inject (such as porous media, especially dense porous media), the multi-sequence fracturing grouting technology of this embodiment is used.

[0069] Secondly, the geological structure and occurrence conditions should be analyzed. When there are obvious and wide fault zones, the grouting pressure should be strictly controlled to prevent high-pressure fracturing grouting from penetrating the water-rich water-conducting channels. Water-blocking materials such as cement-water glass double-liquid grout should be prepared and sealed in time.

[0070] Further analysis of the stress environment of the injected medium is conducted. Generally, the initial splitting grouting pressure (i.e., the initial splitting pressure to open the splitting channel during the first sequential splitting grouting, which is crucial for forming a network through multiple sequential splitting grouting) is determined comprehensively based on factors such as the magnitude of the triaxial stress (burial depth), the compressive and shear strength of the injected medium (cementation), the grout viscosity (resistance), and the groundwater environment. The initial splitting grouting pressure calculation formula is as follows:

[0071] ;

[0072] In the formula:

[0073] P This is the initial fracturing grouting pressure;

[0074] σ min It is the minimum principal stress of the triaxial geostress (including vertical geostress, maximum horizontal principal stress, and minimum horizontal principal stress);

[0075] k The fracture strength factor needs to be determined empirically by combining the bonding properties of the injected medium and its tensile and shear strength.

[0076] r 0 represents the compaction diffusion radius, which needs to be analyzed based on the porosity of the injected medium and the magnitude of the triaxial geostress.

[0077] h The width of the split channel needs to be determined empirically based on the bonding properties and tensile and shear strength of the injected medium (due to the concealed nature of the grouting project, the width of the split channel can be obtained through on-site or indoor pre-tests). h The range of values ​​will provide a basis for subsequent multi-sequence splitting and overlapping mesh grouting implementation.

[0078] μ is a viscosity coefficient of the slurry;

[0079] Q is a flow rate of the slurry.

[0080] Finally, the groundwater occurrence environment is analyzed, including the distribution of groundwater, water head, water-rich period, surface water connectivity, water temperature and chemical composition, etc. The water quantity and pressure near the tunnel face are mastered, and the influence of chemical composition and water temperature on the chemical setting reaction of the slurry material is analyzed.

[0081] It can be understood that the above engineering geological information is provided by the survey unit.

[0082] S12, grouting group hole parameter design, according to the above engineering geological information combined with the water inflow condition (for example, the water inflow per hour, the water inflow size of different hole depths), the grouting target reinforcement range 26 is divided, including the grouting reinforcement range, the grouting length; And clearly the number of grouting holes, the inclination angle and the design depth of the grouting drill hole; According to the size of the ground stress (i.e. three-way ground stress), the first order splitting grouting pressure and the anti-burst rock disc thickness, etc. Site conditions, determine the thickness of the grouting wall, which needs to meet the requirements of high pressure splitting grouting reaction force.

[0083] Generally speaking, the number of grouting holes, angle and depth design need to be determined according to the grouting reinforcement range, the drilling angle and depth, the grouting reinforcement range and the final hole intersection range.

[0084] For example: the grouting reinforcement range in this embodiment exceeds 5-10m above and below the tunnel contour line, the grouting length is 20-25m, and a 1.5-2.0m thick reinforced concrete grouting wall is made in this embodiment.

[0085] It is particularly noted that the multi-order splitting lapping network grouting technology in this embodiment needs to be carried out in the grouting construction, taking group holes as the object. That is, in the set range of the tunnel face, multi-order splitting lapping network grouting construction is implemented in a set number (>10) of grouting holes, so as to realize the splitting of the grouting vein in the space range, and the grouting vein network in the pore medium. The effect of the multi-order splitting lapping network grouting cannot be achieved by single hole or dispersed hole.

[0086] S13, slurry selection and testing, including the initial setting time of the slurry t c and the strength of the slurry after initial setting and the 3 / 7 day strength;

[0087] Since the multi-order split lapping netting grouting technology is developed based on the time-varying viscosity characteristics of the slurry, all the slurries with the time-varying viscosity characteristics are applicable in the multi-order split lapping netting grouting technology. The slurry materials are not limited to the two-liquid cement-based rapid-setting materials, and all the rapid-setting grouting materials with the time-varying viscosity characteristics and the phase change from fluid to solid are applicable.

[0088] Therefore, according to the water inflow conditions on site, the grouting materials with strong time-varying viscosity characteristics such as cement single-liquid slurry (42.5 Portland cement, water-cement ratio of 0.6-0.8), cement-sodium silicate two-liquid slurry (modulus M=3.25, °Bé=40 liquid sodium silicate, cement-sodium silicate volume ratio of 1:1-5:1), and sulphoaluminate cement can be selected.

[0089] To ensure the effect of rapid reinforcement, the cement-sodium silicate two-liquid slurry (a cement-based rapid-setting slurry) (modulus M=3.25, °Bé=40 liquid sodium silicate, cement-sodium silicate volume ratio of 1:1-5:1) is selected in the embodiment. The time-varying viscosity effect of the slurry is the basic reason for the initial setting characteristics of the slurry and the core basis of the multi-order split lapping netting grouting concept. Therefore, before the grouting reinforcement is carried out, the initial setting time of the slurry needs to be determined by using the inverted cup method on site. t c .

[0090] The strength after the initial setting of the slurry and the 3 / 7-day strength are tested, which are the key parameters for the evaluation of the strength and effect of the split grouting reinforcement in the pore medium. The multi-order split lapping netting grouting technology is to increase the number of split grout veins and improve the network skeleton effect, and the strength of the grout is the direct index of the skeleton strength and effect of a single grout vein and the basis for further forming the grout vein network.

[0091] S14. Determine the grouting system 25 according to the construction space on site and the type of the selected slurry.

[0092] In the embodiment, the grouting system 25 adopts a drilling and grouting integrated machine capable of two-liquid grouting, such as the ZJ1500 / 2500 full-hydraulic drilling and grouting integrated machine in the prior art.

[0093] In the grouting process, the P-Q-t monitoring information of the real-time change of grouting flow and pressure with time is crucial to the grouting control method. In the conventional splitting grouting technology, the importance of informationized monitoring is not enough, which belongs to extensive grouting control. The multi-sequence splitting lapping network grouting of the embodiment needs to regulate the real-time data information of the grouting pressure-flow in the grouting process, which belongs to fine grouting control. In the embodiment, the grouting recorder is installed in the grouting system, and the monitoring information is obtained by using the grouting recorder. The grouting recorder can monitor the grouting outlet pressure of the grouting pump of the drilling-grouting integrated machine, and can also monitor the grouting flow of the grouting pump of the drilling-grouting integrated machine.

[0094] According to the current splitting grouting requirements, the grouting pump of the drilling-grouting integrated machine can be adjusted by monitoring the grouting flow and pressure, so as to ensure the accuracy of the grouting flow and pressure, accurately control the grouting pressure and flow, and determine whether the splitting channel is opened in the current sequence splitting grouting according to the monitoring information of the grouting recorder.

[0095] It should be noted that all grouting projects are concealed projects, and the diffusion characteristics of the grouting slurry in the grouting medium cannot be seen in the grouting process. Therefore, it is necessary to analyze and judge the progress in the grouting medium from the real-time feedback information. In the multi-sequence splitting lapping network grouting process, the importance of data analysis and collection needs to be improved, and scientific analysis and scientific control of the grouting process need to be carried out.

[0096] S2, the multi-sequence splitting lapping network grouting tool body is used to carry out multi-sequence splitting grouting construction, as shown in Figure 4 、 Figure 5 , the multi-sequence splitting lapping network grouting tool body is used to carry out multi-sequence splitting grouting construction in a single grouting hole in the grouting target reinforcement range to form a grouting body 19 with multiple splitting grout veins, and the multi-sequence splitting lapping network grouting tool body is used to carry out multi-sequence splitting grouting construction in multiple grouting holes in the grouting target reinforcement range to form multiple grouting bodies 19, and the splitting grout veins of the multiple grouting bodies 19 are further lapped into a network. That is, one grouting pipe is arranged in each grouting hole of the grouting group hole, a grouting body 19 including multiple splitting grout veins is formed at each grouting pipe, and the grouting bodies 19 at multiple grouting pipes are lapped in the grouting target reinforcement range 26 and form a network in the pore medium.

[0097] As shown in Figure 6 、 Figure 7 、 Figure 9 , when the first sequence splitting grouting is carried out, the grouting pressure is monitored to rise to the splitting starting pressure P 1, P 1 of the first sequence splitting grouting, which is equal to the initial splitting grouting pressure P , then the grouting pressure drops instantaneously, and the drop amplitude exceeds the set proportion, which indicates that the grouting slurry of the first sequence splitting grouting opens the splitting channel under the maximum horizontal stress (σ h)13 opens the first-order splitting channel 7, at this time the slurry enters the first-order splitting channel 7, so there will be a transient drop in pressure, continue to inject until the slurry pressure is raised again and tends to P 1, at this time the slurry fills the first-order splitting channel 7, and forms the first-order splitting vein 10 in the first-order splitting channel 7, at this time the injection pipe ball valve can be closed to suspend injection. This process realizes the filling and compaction of the first-order splitting channel and the surrounding injected medium.

[0098] After the first-order splitting injection suspension injection reaches the injection interval time, secondary splitting injection is carried out, and the pressure of the secondary splitting injection is raised to the splitting pressure of the previous splitting injection (i.e. the first-order splitting injection) P 1) After that, the pressure continues to rise and reaches a new splitting pressure P 2, after which there will also be a transient drop in injection pressure, and the drop is more than the set proportion, at this time the slurry of the secondary splitting injection turns to extend in the first-order splitting vein 10, and opens the next-order splitting channel 9 (here the next-order splitting channel 9 is the secondary splitting channel) along the maximum horizontal stress direction, the slurry enters the secondary splitting channel, and continues to inject until the slurry pressure is raised again and tends to P 2, after the slurry forms the secondary splitting vein 11 in the secondary splitting channel, the injection pipe ball valve is closed to suspend injection.

[0099] In this embodiment, when the slurry pressure drop is more than 30% of the peak pressure of each order splitting injection, it is considered that the slurry has effectively split and spread in the formation; if the injection pressure drop is less than 30% of the peak pressure of each order splitting injection, it is considered that there is only stress redistribution in the formation, and the single-order splitting channel is not completely formed.

[0100] It needs to be explained that during the secondary splitting injection, the slurry pressure of the secondary splitting injection needs to be greater than the coupling effect of the ground stress constraint and the strength of the injected medium (including the strength of the initial setting slurry body), so as to reach the peak pressure of splitting, and under the blocking effect of the initial setting solid slurry vein in the first-order splitting channel, force the slurry of the secondary splitting injection to find a secondary weak position, and then open a secondary splitting channel along the secondary weak fracture, which will also show a transient drop in injection pressure with a drop amplitude exceeding the set proportion of the peak pressure.

[0101] It needs to be explained that based on the strong rheological property and thixotropy of the quick-setting slurry, the interval time between adjacent order splitting injections can promote the slurry of the previous order splitting injection to be solidified into a solid slurry vein in the previous order splitting channel, realize temporary blocking of the previous order splitting channel, and provide physical blocking for hindering the slurry of the subsequent order splitting injection to continuously spread along the first-order splitting channel.

[0102] It should be noted that, as shown in Figure 6 , by pausing grouting between adjacent sequential split grouting, the chemical reaction time of the slurry is utilized to promote initial setting of the slurry and temporarily block the previous sequential split channel. This method is suitable for poor cementation, small ground stress, and small initial split pressure of the pore medium.

[0103] In weakly cemented, high ground stress, and high initial split pressure pore media, high-pressure and high-flow processes are often used to implement split grouting treatment, and it is more necessary to accelerate the initial setting of the grouting slurry to achieve the blocking of the previous sequential split channel and improve the blocking strength. Therefore, in some embodiments, the slurry ratio is adjusted and the slurry is accelerated to set between adjacent sequential split grouting, as shown in Figure 7 , the slurry ratio is adjusted after the split channel is clearly opened, and the slurry with adjusted ratio is injected during the subsequent grouting process to accelerate the initial setting of the slurry.

[0104] To ensure the strength of the reinforcement effect, in some embodiments, the slurry is a cement single slurry. The advantages of the cement single slurry are: 1) the cement single slurry has stronger permeability than the cement-based quick-setting slurry, and has an advantage in permeating and diffusing around the medium to be injected for each sequential split channel and reinforcement effect; 2) the strength of the cement single slurry after chemical setting is stronger than that of the cement-based quick-setting slurry, which is more conducive to improving the overall stability of the medium to be injected. However, the disadvantage of the cement single slurry is that the initial setting time is too long, and it cannot quickly set to block the previous sequential split channel.

[0105] Therefore, when the slurry is replaced by the cement single slurry, the initial setting time of the cement single slurry with a quick-setting agent is tested. During the process of each sequential split grouting, the cement single slurry is used for grouting first, and the quick-setting agent (such as sodium silicate and sodium aluminate powder) is added to the cement single slurry during the stage of continuously grouting until the slurry pressure is raised again and tends to peak pressure (i.e. the stage of filling each sequential split channel and extruding the medium to be injected around it), so that the cement single slurry quickly sets to block the current sequential split channel. During the process of subsequent sequential split grouting, the cement single slurry is continuously used for grouting, and the remaining steps are different.

[0106] According to the above grouting process, a plurality of subsequent sequential split channels 9 are formed around the first sequential split slurry vein, and a plurality of subsequent sequential split slurry veins are formed, such as three (or more) sequential split slurry veins 12. The first sequential split slurry vein 10 and the plurality of subsequent sequential split slurry veins around it together form a grouting body 19.

[0107] That is, each sequential split grouting is formed in the direction of the maximum horizontal ground stress (σ h ) 13 to form a split channel for each sequence, and a split slurry vein for each sequence is formed in the split channel for each sequence; as Figure 6As shown, the interval between two adjacent orders of split grouting construction is set as the grouting time, and the split pressure of the slurry is increased step by step in the multiple order grouting.

[0108] As shown in Figure 4 , by performing multiple order split grouting in the grouting group hole, a plurality of overlapping grouting bodies 19 are formed, and in the water-rich soft and dense stratum, the single-hole split turning of the split main trunk slurry vein, the double-hole slurry vein overlapping, and the group-hole slurry vein connection into a network are realized, so that the slurry vein network plays a skeleton support role in the stratum, and the purpose of improving the overall stability and excavation safety is achieved.

[0109] As shown in Figure 5 , in this embodiment, the grouting body 19 includes a first order split slurry vein 10, a second order split slurry vein 11, and a third (or multiple) order split slurry vein 12. It should be noted that the second order split slurry vein 11 and the third (or multiple) order split slurry vein 12 are formed around the first order split slurry vein 10 and extend from the first order split slurry vein 10. As shown in Figure 5 , the slurry vein fluid phase-solid phase schematic strip 21 of the three split slurry veins includes a front-end solid phase split slurry vein 23 and a rear-end fluid phase split slurry 22. This is because the later order split slurry vein is formed when the previous order split slurry vein has not completely solidified.

[0110] Specifically, S21, the grouting holes are drilled according to the number, angle and depth determined in S12, the grouting pipes 17 are installed in the multiple grouting holes, the grouting pipe line (i.e. the tail end of the grouting pipe is connected with the grouting system) is connected between the grouting system 25 (drilling and grouting integrated machine) and the grouting pipe 17, and the grouting pipe ball valve is arranged at the connection.

[0111] In the multiple order split overlapping network grouting design, the sealing property of the grouting pipe 17 needs to be ensured. In general, the grouting pipe 17 needs to exceed the thickness of the grouting wall 18 by 3-7 m, which can ensure the effectiveness of the high-pressure split and the load-bearing property. The sealing between the grouting pipe 17 and the hole wall needs to ensure the sealing effect after installation to avoid engineering quality accidents such as hole wall back grouting during the split grouting process. For the sealing property of the grouting hole, the flange sealing or geological threaded casing measures are adopted for sealing. When high-pressure splitting (>10 MPa) is encountered, rubber sealing pads or metal pads are avoided between the flanges, and special flanges with concave-convex surfaces that can withstand high pressure need to be replaced.

[0112] S22, as shown in Figure 4 , Figure 5 , the first order split grouting finally forms the first order split slurry vein 10;

[0113] Specifically, first, the constant flow Q1. Injecting slurry into the injection pipe 17, for example, at a rate of 50-100 L / min. Next, observe the real-time data changes in the current slurry pressure in the grouting recorder: (1) If the slurry pressure does not significantly increase within 10 minutes, and there is no slurry running phenomenon on the working face (for shallow tunnels, observe whether there is surface slurry running), it indicates that there is a large slurry inlet space in the stratum, and the slurry flow needs to be increased, or even the injection sealing material needs to be replaced. If the pressure does not increase within 20 minutes, the injection channel needs to be sealed. (2) If the slurry pressure significantly increases and then stabilizes without significant instantaneous drops, it indicates that a hole extrusion slurry package 20 is formed at the injection orifice, and then a fracture channel is encountered. The fast-setting time can be appropriately increased (the slurry concentration is increased, and the cement-water glass volume ratio is increased). When the slurry solidifies, the injection pressure will significantly increase, and the injection should be stopped at this time. (3) If the slurry pressure significantly increases to P 1 (the peak pressure of the first-order splitting injection is equal to the initial splitting injection pressure) and there is a significant instantaneous drop, for example, a drop of 30%-50% of P 1, as shown in Figure 5 , it indicates that the slurry forms a hole extrusion slurry package 20 around the orifice of the injection pipe 17, as shown in Figure 9 , and the slurry opens a first-order splitting channel 7 in the pore medium 1. That is, when the slurry flows in the injection pipe, the pressure increases. When the slurry flows out of the injection pipe and fills the injection hole, the pressure continues to increase, reaches the splitting injection pressure, and splits the pore medium, causing an instantaneous drop in pressure. As the slurry fills the splitting channel, the pressure gradually increases.

[0114] Finally, extruding the first-order splitting channel 7. After opening the first-order splitting channel 7 in the pore medium 1, constant flow Q 1 is maintained for continuous injection, so that the slurry pressure increases again and tends to P 1. It is considered that the first-order splitting injection has reached the end standard, and the injection is paused to obtain the first-order splitting slurry vein 10. The significance is that after opening the first-order splitting channel, the first-order splitting channel is completely filled, and the pore medium 1 near the first-order splitting channel is further extruded.

[0115] As shown in Figure 9 , in this embodiment, the first-order splitting channel 7 is opened during the first-order splitting injection, and the injection is stopped after further extruding the first-order splitting channel 7, which can form the first-order splitting slurry vein 10. As shown in Figure 8As shown, in the existing high-pressure fracturing grouting technology, after opening the fracturing channel, grouting must continue. The grout tends to fracture along the direction of the maximum principal stress, forming a single dominant fracture channel. The grout will spread over long distances, exceeding the target reinforcement range. This causes the grout to travel further and further away, and the pressure at the grouting pipe must increase, resulting in a continuous increase in pressure. Eventually, the grouting wall will be unable to withstand the pressure and will be destroyed.

[0116] S23. Wait for the opportunity of secondary fracturing grouting.

[0117] After the initial splitting grouting completion criteria are met, stop pumping grout and close the ball valve on the grouting pipe.

[0118] The timing of secondary fracturing grouting refers to the grouting interval between the completion of the first-sequence fracturing grouting and the commencement of the second-sequence fracturing grouting. For example, the grouting interval between the first-sequence fracturing grouting and the second-sequence fracturing grouting is... T 1-2 The grouting interval between the secondary and tertiary fracturing grouting is... T 2-3 The grouting interval between the three-stage fracturing grouting and the multi-stage fracturing grouting is: T 3-n .

[0119] Based on the data and conclusions from the existing indoor and field tests of multi-sequence splitting lap splicing mesh grouting technology, the optimal grouting interval between each two sequences is 50%–75%. t c Grouting interval less than 50% t c This can cause subsequent fracturing grouting to reopen the channels from the previous fracturing process, preventing the formation of new fracturing grout veins; the grouting interval is less than 75%. t c This can cause the grout to deflect near the grouting pipe during subsequent fracturing grouting, thus reducing the number of fracturing grout veins; the interval between two grouting sessions should not exceed the initial setting time of the grout. t c 90%, more than 90% t c It is no longer possible to generate split magma veins.

[0120] It should be noted that, due to the complexity of the injected formation 27 and the differences in material volume, the initial setting time t of the slurry determined by the inverted cup method is... cGenerally, the initial setting time of the slurry in the formation is less than the initial setting time of the slurry in the slurry tank. Therefore, during the implementation of the multi-order split lapping network grouting technology, only the ball valve of the grouting hole needs to be closed during the interval between each two orders of grouting, without the need to disconnect the grouting pipeline, which is conducive to the implementability of the multi-order split lapping network grouting technology.

[0121] After reaching the set second-order split grouting opportunity (interval T 1-2 ), the ball valve of the grouting pipe is opened, and the second-order split grouting is started.

[0122] S24, second-order split grouting, as shown in Figure 9 , Figure 10 , the final second-order split grout 11 is formed.

[0123] The construction content of the second-order split grouting is consistent with that of the first-order split grouting in S22, and the difference lies in that the split starting pressure P 2 of the second-order split grouting is greater than P 1, and the constant flow Q 2 during the second-order split grouting is greater than Q 1 during the first-order split grouting.

[0124] Due to the time-varying characteristics of the slurry viscosity, the slurry part of the first-order split grouting tends to initial setting, or in other words, the slurry part of the previous-order split grouting tends to initial setting when the second-order split grouting is performed. As shown in Figure 4 , Figure 9 , in the process of multi-order split lapping network grouting, the pore medium 1 is extruded and compacted to become a multi-order split lapping network grouting pore medium 2. It can be understood that, due to the extrusion and compaction of the first-order split grouting to the pore medium 1, the split pressure during the second-order split grouting will relatively increase. However, the pressure during the second-order split grouting is less than the continuously increasing pressure during the traditional high-pressure split grouting, because the split starting pressure of the traditional high-pressure split grouting is consistent with the peak pressure of the first-order split grouting in this embodiment, but due to the continuous grouting of the high-pressure grouting, the pressure continuously increases, and the subsequent pressure is much higher than the peak pressure of the second-order split grouting in this embodiment.

[0125] As shown in Figure 9 , during the second-order split grouting, the grouting pipe 17 is completely filled with the fluid-phase slurry 4, while in the first-order split channel 7, the first-order split grout 10 has a completely solid-phase grout 5 at the tip, a fluid-solid mixed slurry 6 in the middle, and a completely fluid-phase slurry 4 at the tail.

[0126] As shown in Figure 9 , Figure 10As shown, the fully solid phase slurry vein 5, which has been in solid phase, changes the local stress distribution of the tip of the first-order splitting slurry vein 10, resulting in horizontal stress change (Δ σ h ) 15 caused by the primary solid phase slurry vein, and vertical stress change (Δ σ v ) 16 caused by the primary solid phase slurry vein; when σ h，max + Δ σ h < 0 σ v，min + Δ σ v , the critical condition of splitting turning is reached, the slurry of the second-order splitting injection will turn, and the slurry of the second-order splitting injection will turn in the flow-solid phase mixed slurry 6 of the first-order splitting slurry vein 10, as Figure 9 shown, forming a new position and direction of the later-order splitting diffusion 8, and the slurry bursts out of the first-order splitting slurry vein 10 into the local multi-order splitting lapping network injection pore medium 3.

[0127] The slurry of the second-order splitting injection will bypass the influence range of the "splitting- compaction-primary solidification" of the first-order splitting slurry vein, that is, after the fully solid phase slurry vein 5 of the first-order splitting slurry vein 10, it returns to the direction of the maximum principal stress to form a later-order splitting channel 9, and the second-order splitting slurry vein 11 is formed therein.

[0128] S25, waiting for a three (multi) order splitting injection opportunity.

[0129] The content of waiting for a three (multi) order splitting injection opportunity is basically similar to that of waiting for a two order splitting injection opportunity in S23.

[0130] S26, three (multi) order splitting injection, forming a three (multi) order splitting slurry vein 12.

[0131] Similar to the content of S22 and S24, that is, during the later-order splitting injection, the constant flow Q n during the later-order splitting injection process is greater than the constant flow Q Q n-1 during the previous-order splitting injection process, and the splitting starting pressure P n of the later-order splitting injection is greater than the splitting starting pressure P n-1 of the previous-order splitting injection.

[0132] As Figure 9As shown, the slurry 4 in the injection pipe 17 is still in a complete fluid phase, but the flow-solid mixed slurry 6 in the first-order splitting slurry vein 10 has changed into a complete solid phase slurry vein 5 at the position where the slurry of the second-order splitting injection is diverted.

[0133] Therefore, although the three (or more) order splitting injection also causes new splitting slurry veins to be diverted, the diversion position of the three (or more) order splitting injection is closer to the injection pipe 17 than that of the two-order splitting injection. On the other side of the first-order splitting slurry vein 10, the reason is that the slurry will preferentially form a new splitting channel on the side where the slurry has not yet solidified, i.e., the weakest position. After bypassing the first-order splitting channel, the three (or more) order splitting injection will also return to the direction of the maximum principal stress to form a three (or more) order splitting channel and form a three (or more) order splitting slurry vein 12 in the three (or more) order splitting channel.

[0134] That is, after the completion of the first-order splitting injection, the slurry in the injection pipe is still in a complete fluid phase during all subsequent-order splitting injections. The slurry diversion point of the subsequent-order splitting injection is located at a position closer to the injection pipe than the first-order splitting injection at the first-order splitting slurry vein diversion point. The slurry of the subsequent-order splitting injection is diverted in the direction where the first-order splitting slurry vein is not filled, forming a subsequent-order splitting slurry vein.

[0135] By carrying out multi-order splitting lapping network injection with different orders and different injection intervals between each order, it is beneficial to enrich the splitting position and diffusion direction of each order of multi-order splitting lapping network injection. The disadvantageous factor that the slurry preferentially diffuses along the dominant splitting channel in the direction of the maximum principal stress to form a limited number of main splitting slurry veins in a single direction is avoided in the traditional splitting injection technology.

[0136] S27, end of injection.

[0137] First, the end of injection needs to meet the end of injection criteria. The end of injection criteria often depends on two aspects: (1) end of injection flow rate, when the injection flow rate continuously decreases below a certain value, it is considered that the end of injection flow rate criteria is met, for example, 15 L / min. (2) end of injection pressure, when the injection pressure reaches a preset value and is stable, it is considered that the end of injection pressure criteria is met. The preset value of the end of injection pressure needs to be analyzed according to the site conditions. When the pore medium has cementation, or the segmented advancing injection hole is a deep hole (>15 m), the end of injection pressure can be appropriately increased, for example, 6-9 MPa, which needs to be analyzed according to the engineering conditions.

[0138] It is emphasized that in high-pressure grouting engineering, construction safety should be paid attention to, and the deformation of surrounding rock in the engineering site should be monitored to meet the requirements, and the face should not be cracked or have abnormal conditions such as outburst, under the premise of meeting the above grouting end criteria, the multi-sequence splitting and lapping network grouting operation is completed.

[0139] Secondly, close the grouting pipe ball valve. After completing the multi-sequence splitting grouting operation, set the grouting pipe ball valve to be closed first, and then the grouting pipe is disconnected. Under the condition that the grouting pipe ball valve is opened, the grouting pipe is strictly prohibited to be disconnected, so as to ensure the retention of grout in the grouting pipe and the solidification effect of the grout.

[0140] Finally, clean the grouting system. Clean the drilling and grouting integrated machine and the grouting pipe to prepare for subsequent multi-sequence splitting and lapping network grouting in other holes.

[0141] S3, tunnel 24 safe excavation.

[0142] S31, grouting reinforcement maintenance.

[0143] Wait for the strength of the grout vein to improve. After completing the multi-sequence splitting and lapping network grouting operation, excavation cannot be carried out immediately, and the strength of the grout vein needs to be improved, and after the solid grout vein skeleton is formed, the inspection hole construction or tunnel excavation can be carried out. During the waiting process, tunnel support and other work can be carried out at the same time, without delaying the straight-line period.

[0144] S32, grouting effect inspection.

[0145] Common grouting effect inspection includes: making 5% to 10% of the total number of inspection holes, drilling television analysis, hole grout vein observation, in-situ mechanical test, pressure test, etc.

[0146] S33, tunnel excavation.

[0147] After meeting the tunnel safe excavation standard, the grouting wall 18 is broken, and the tunnel 24 excavation work is carried out as weakly as possible by mechanical excavation, controlled blasting and other methods.

[0148] Embodiment 2

[0149] The pore medium multi-sequence splitting and lapping network grouting control system disclosed in this embodiment can implement the pore medium multi-sequence splitting and lapping network grouting control method disclosed in embodiment 1, which includes a grouting module configured to open a grouting group hole in a grouting target reinforcement range, and perform multi-sequence splitting grouting in a single grouting hole.

[0150] The multiple-order split grouting is performed by setting a time interval between adjacent orders of split grouting, using the time-varying viscosity of the slurry, and the slurry pulse tip formed by the previous order of split grouting in the direction of the maximum principal stress tends to initial setting, so as to change the stress distribution of the adjacent pore medium and temporarily block the previous split channel, thereby forcing the slurry of the subsequent order of split grouting to change direction and diffuse along the newly generated split channel, and after bypassing the previous order of split grouting and changing the stress distribution of the pore medium, the slurry continues to develop in the direction of the maximum principal stress, and further forms a grouting body containing multiple branch slurry pulses.

[0151] The analysis module is further included, and the analysis module is configured to determine a reinforcement range of a grouting target in the pore medium, an initial split grouting pressure P 1, the initial setting time of the slurry, and the interval time of the grouting is determined according to the initial setting time;

[0152] The grouting module includes a grouting system and a grouting recorder, the grouting recorder monitors the slurry pressure of the grouting system, and when the grouting system performs the first order of split grouting in a single hole of the grouting hole group, the grouting system is stopped when the slurry pressure reaches P 1, the first order of split grouting slurry pulse is formed in the direction of the maximum horizontal stress, and the grouting is stopped after the set condition is reached;

[0153] The grouting is stopped for an interval time, and the second order of split grouting is performed, and when the slurry pressure reaches P 2, P 2 is greater than P 1, a branch is generated on the first order of split grouting slurry pulse to generate a second order of split grouting slurry pulse, and the grouting is stopped after the set condition is reached;

[0154] The grouting is stopped again for an interval time, and the third order of split grouting is performed, and when the slurry pressure reaches P 3, P 3 is greater than P 2, another branch is generated on the first order of split grouting slurry pulse to generate a third order of split grouting slurry pulse, and the grouting is stopped after the set condition is reached;

[0155] The multiple order split grouting is performed according to the above logic, a plurality of branches are generated on the first order of split grouting slurry pulse to generate a plurality of subsequent order of split grouting slurry pulses, and the grouting body is formed.

[0156] A plurality of grouting bodies are formed in the reinforcement range of the grouting target, and the plurality of grouting bodies are overlapped to form a network in the reinforcement range of the grouting target.

[0157] The set condition for stopping the grouting is that if the slurry pressure monitored by the grouting recorder rises to the set pressure, the pressure appears a transient drop, and the drop amplitude exceeds the set proportion, the grouting is continued until the slurry pressure rises again and tends to the set pressure, and the grouting is stopped.

[0158] Example 3

[0159] The control terminal disclosed in the embodiment comprises a processor and a memory, the processor is used for implementing instructions, the memory is used for storing a plurality of instructions, the instructions are suitable for being loaded and executed by the processor to implement the pore medium multi-sequence split lap joint netting grouting control method disclosed in the embodiment 1.

[0160] Although the specific embodiments of the present application are described above with reference to the drawings, the description is not a limitation on the scope of protection of the present application, and those skilled in the art should understand that various modifications or changes made on the basis of the technical solutions of the present application without creative labor are still within the scope of protection of the present application.

Claims

1. A method for controlling grouting in porous media involving multi-sequence splitting and overlapping mesh formation, characterized in that, Within the reinforcement range of the grouting target, a group of grouting holes is opened, and multiple sequential splitting grouting is performed in a single grouting hole; During multiple sequential splitting grouting, the interval between adjacent sequential splitting grouting is set at a certain time. The tip of the grout vein formed in the direction of the maximum principal stress of the previous sequential splitting grouting tends to initially set, which forces the grout of the subsequent sequential splitting grouting to turn and diffuse along the newly generated splitting channel, thereby forming a grouting body containing multi-branched grout veins. During the initial fracturing grouting, when the grout pressure reaches P 1. The grout forms the first sequential splitting grout vein in the direction of maximum horizontal stress; after pausing the grouting interval, a second sequential splitting grouting is performed in the same grouting hole until the grout pressure reaches... P 2, P 2 greater than P 1. Branches are generated on the first-order split grout vein to form a second-order split grout vein; multiple split grouting operations are performed according to the above logic to generate multiple branches on the first-order split grout vein to form multiple subsequent split grout veins, which together form the grout body. The conditions for pausing grouting in each sequence of splitting grouting are as follows: if the grout pressure rises to the splitting pressure and the pressure drops momentarily, and the drop exceeds the set ratio, then grouting continues until the grout pressure rises again and tends to the set pressure, at which point grouting stops.

2. The method for controlling grouting of porous media through multi-sequence splitting and overlapping as described in claim 1, characterized in that, Determine the target reinforcement range and initial fracturing grouting pressure in the porous medium. P 1. The initial setting time of the grout is used to determine the grouting interval.

3. A method for controlling grouting of porous media through multi-sequence splitting and overlapping as described in claim 1 or 2, characterized in that, Multiple grouting bodies are formed within the grouting target reinforcement area, and these multiple grouting bodies overlap to form a network within the grouting target reinforcement area.

4. The method for controlling grouting of porous media through multi-sequence splitting and overlapping as described in claim 2, characterized in that, The optimal range for the grouting interval is 50% to 75% of the initial setting time, and it shall not exceed 90% of the initial setting time.

5. The method for controlling grouting of porous media through multi-sequence splitting and overlapping as described in claim 1, characterized in that, The grouting target reinforcement range and initial splitting grouting pressure are obtained through the analysis of engineering geological information of the strata to be grouted in the tunnel. The engineering geological information includes the lithology of the grouted medium, geological structure occurrence conditions, geostress occurrence environment, and groundwater occurrence environment.

6. The method for controlling grouting of porous media through multi-sequence splitting and overlapping as described in claim 1, characterized in that, Before grouting, multiple grouting holes are drilled and grouting pipes are installed. The end of the grouting pipe is connected to the grouting system, and a grouting recorder is installed to monitor the grout pressure at the outlet of the grouting system and the grout flow rate at the suction outlet.

7. The method for controlling grouting of porous media through multi-sequence splitting and overlapping as described in claim 6, characterized in that, The slurry is a cement-based quick-setting slurry.

8. The method for controlling grouting of porous media through multi-sequence splitting and overlapping as described in claim 6, characterized in that, When the grout is a single-component cement grout, the initial setting time of the single-component cement grout with added quick-setting agent is tested first. During each sequential splitting grouting process, the single-component cement grout is used for grouting first. When the grouting pressure is increased to the set pressure, and the grouting pressure drops momentarily and the drop exceeds the set ratio, an accelerator is added to the cement grout. Grouting continues until the grout pressure is increased again and tends to the set pressure, at which point grouting is stopped.

9. The method for controlling grouting of porous media through multi-sequence splitting and overlapping as described in claim 6, characterized in that, During the secondary fracturing grouting, the grouting pipe contains a completely fluid phase slurry, the tip of the first fracturing slurry vein is a completely solid phase slurry vein, the middle part is a fluid-solid mixed slurry, and the tail end is a completely fluid phase slurry. The pore medium within the tip range of the first fracturing slurry vein is compacted by the completely solid phase slurry vein.

10. The method for controlling grouting of porous media through multi-sequence splitting and overlapping as described in claim 9, characterized in that, The grout of the secondary-sequence splitting grout is deflected in the fluid-solid phase mixture of the primary-sequence splitting grout vein, and after bypassing the pore medium compacted by the primary-sequence splitting grout vein, it returns to the direction of maximum principal stress to form the secondary-sequence splitting grout vein.

11. The method for controlling grouting of porous media through multi-sequence splitting and overlapping as described in claim 10, characterized in that, During the subsequent sequential splitting grouting following the secondary sequential splitting grouting, the grouting pipe still contains a completely fluid phase grout. The turning point of the subsequent sequential splitting grouting is closer to the grouting pipe than the turning point of the secondary sequential splitting grouting, and the grout of the subsequent sequential splitting grouting turns towards the direction where the secondary sequential splitting grout vein was not filled, thus forming the subsequent sequential splitting grout vein.

12. A grouting control system for multi-sequence splitting and overlapping mesh formation in porous media, characterized in that, Includes a grouting module, which is configured to open a group of grouting holes within the target reinforcement area and perform multiple sequential splitting grouting within a single grouting hole; During multiple sequential splitting grouting, the interval between adjacent sequential splitting grouting is set. The tip of the grout vein formed in the direction of the maximum principal stress of the previous sequential splitting grouting tends to initially set, which forces the grout of the subsequent sequential splitting grouting to turn and diffuse along the newly emerging splitting channels, thereby forming a grouting body containing multi-branched grout veins.

13. The porous media multi-sequence splitting and overlapping mesh grouting control system as described in claim 12, characterized in that, It also includes an analysis module configured to determine the target reinforcement range for grouting in porous media and the initial fracturing grouting pressure. P 1. The initial setting time of the grout is used to determine the grouting interval. The grouting module includes a grouting system and a grouting recorder. The grouting recorder monitors the grout pressure injected by the grouting system. During the initial sequential splitting grouting, when the grout pressure reaches... P 1. The grout forms the first sequence splitting grout vein in the direction of maximum horizontal stress; Pause the grouting interval and perform secondary sequential fracturing grouting in the same grouting hole until the grout pressure reaches... P 2, P 2 greater than P 1. Branching occurs on the primary order splitting vein, generating secondary order splitting veins; Following the above logic, multiple sequential splitting grouting processes are performed, generating multiple branches on the first sequential splitting grout vein, which in turn generate multiple subsequent sequential splitting grout veins, together forming the grouting body.

14. A porous media multi-sequence splitting and overlapping mesh grouting control system as described in claim 12 or 13, characterized in that, Within the grouting target reinforcement area, multiple grouting bodies are formed by multiple sequential splitting grouting operations, and these multiple grouting bodies overlap to form a network within the grouting target reinforcement area.

15. A porous media multi-sequence splitting and overlapping mesh grouting control system as described in claim 13, characterized in that, If the grout pressure monitored by the grouting recorder rises to the set pressure, and the pressure drops momentarily, and the drop exceeds the set ratio, then grouting continues until the grout pressure rises again and tends to the set pressure, at which point grouting stops.

16. A control terminal, comprising a processor and a memory, wherein the processor is used to implement instructions; and the memory is used to store multiple instructions, characterized in that, The instructions are adapted to be loaded by a processor and executed by the processor to provide a method for controlling the multi-sequence splitting and overlapping of porous media into a network for grouting control, as described in any one of claims 1-11.

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