Stepless variable-slurry variable-pressure whole-process intelligent grouting control method

Abstract

The invention provides a stepless variable-slurry variable-pressure whole-process intelligent grouting control method which comprises the following steps: in an initial grouting stage, calculating grouting starting pressure, target flow and a viscosity coefficient according to a hole section permeable rate, in a single-stage grouting stage, keeping a water-cement ratio unchanged, and controlling the product of the pressure and the flow to be a constant value by boosting and reducing flow, and in a variable water-cement ratio stage, controlling the product of the pressure and the flow to be a constant value by controlling the product of the target flow and the viscosity coefficient to be a constant value. When the slurry of the level cannot be further increased or decreased, the slurry with the lower water-cement ratio is switched to, the pressure and the flow are cooperatively adjusted, and in the grouting ending stage, the designed maximum pressure and the designed low flow are maintained, and the stratum permeable rate after grouting is subjected to inversion analysis till the ending standard is met. And in combination with real-time monitoring data, automatic, intelligent and whole-process control is achieved, and it is ensured that slurry can be deposited in a target area and cracks are effectively blocked.

Description

Technical Field

[0001] This invention relates to the field of bedrock grouting engineering technology, and in particular to a fully intelligent grouting control method with stepless variable grout pressure. Background Technology

[0002] Grouting of bedrock fissures is a commonly used seepage control technique in water conservancy and hydropower engineering. Its main purpose is to seal seepage channels by injecting grout into bedrock fissures, reducing the permeability of the rock mass, and thus improving the overall safety and durability of the project. However, because bedrock fissures are difficult to observe directly and the grout flow mechanism is extremely complex, controlling the grouting process within the fissures is extremely difficult and the construction is highly concealed. Currently, engineering projects mainly rely on controlling key parameters such as grouting pressure, flow rate, and water-cement ratio to achieve fissure sealing. However, how to set and adjust these control parameters throughout the grouting process has always been a key focus and challenge in grouting theory and practice research.

[0003] In early grouting theory research, Lombardi's Grouting Intensity Number (GIN) theory had a significant influence. Based on the assumption of an ideal flat plate fracture, this theory establishes a simplified mathematical-physical model by setting the product of grouting pressure and injection volume as a constant, to describe the flow and diffusion of grout in fractures. The GIN model is simple, and its parameters are easy to measure, thus it has been widely used for field grouting control, especially in Europe and other regions where it has become a standardized method. However, the GIN theory only focuses on the ideal situation where the fracture is completely filled at the end of grouting, failing to reveal the complete process from start to finish and neglecting the dynamic closure behavior of the fracture during grouting. Furthermore, the theory requires the use of a single stable grout, but under complex geological conditions, the permeability characteristics of fractures in different borehole sections vary greatly, and a single grout often cannot meet the control requirements of all sections, thus limiting its applicability. Moreover, the GIN theory lacks clear specifications and explanations regarding grout pressure and grout drainage mechanisms, making it difficult to provide comprehensive guidance for engineering practice and, in fact, unapplicable in most projects both domestically and internationally.

[0004] To compensate for the shortcomings of theoretical models, various experience-based grouting control methods have been developed in engineering practice. The most common of these is the "constant flow and pressure increase method," which maintains a constant flow rate in the initial stage of grouting and gradually increases the pressure to force the grout into the fissures and achieve sealing. This method is simple to operate, but relies on manual experience and cannot dynamically respond to real-time changes in the fissure state. Later, the "adaptive grouting control method" and the "three-zone, five-segment control method" introduced the concept of phased control, setting different pressure and flow ranges to more precisely regulate the grouting process. For example, the three-zone, five-segment control method divides the grouting process into different stages, requiring cyclical adjustments between pressure increase and flow decrease to allow the grout to gradually penetrate the fissures. However, while these methods improve control accuracy to some extent, their parameter selection mainly relies on construction experience and lacks solid theoretical support. In particular, they lack clear judgment criteria for the grout variation process, and the switching between different stages often depends on experience or on-site trial and error, easily resulting in grout waste or incomplete sealing.

[0005] In general, existing grouting theories and methods suffer from two major problems. First, there is a disconnect between theory and practice. GIN theory provides a simplified mathematical model but neglects key physicochemical processes such as grout deposition, fracture closure, and consolidation drainage, failing to describe the dynamic evolution in real grouting processes. While empirical methods originate from engineering practice, they lack theoretical support, resulting in opaque control processes that are difficult to replicate and promote. Second, control strategies only address single-stage grouting processes, i.e., when the water-cement ratio remains constant; there are no clear regulations for controlling variable grout processes. Parameter adjustments are staged and graded, exhibiting discreteness and lag, failing to achieve real-time, continuous dynamic response. Especially under complex geological conditions, they cannot automatically optimize pressure, flow rate, and water-cement ratio based on real-time changes in fracture permeability, leading to ineffective grouting or unstable grouting effects, and even triggering fracturing failure.

[0006] With the increasing demands for intelligent construction in modern water conservancy and hydropower projects, the limitations of traditional grouting control methods are becoming increasingly apparent. The future trend in grouting control is to establish a scientific theoretical model and achieve intelligent control of the entire grouting process through sensors, the Internet of Things, and intelligent control algorithms. This not only eliminates reliance on manual experience but also enables stepless adjustment of pressure, flow rate, and water-cement ratio, allowing for effective grout deposition and sealing in fissures, fundamentally improving grouting efficiency. Therefore, designing a stepless variable grout and pressure intelligent grouting control method for the entire process is essential. Summary of the Invention

[0007] In order to overcome the shortcomings of the existing technology, the purpose of this invention is to provide a fully intelligent grouting control method with stepless variable grout pressure.

[0008] To achieve the above objectives, the present invention provides the following solution: This invention also provides a fully intelligent grouting control method with stepless variable grout pressure, comprising: Step 1: In the initial stage of grouting, calculate the starting pressure, target flow rate, and viscosity coefficient based on the permeability of the borehole section; Step 2: In the single-stage grouting stage, keep the water-cement ratio constant and control the product of pressure and flow rate to a constant value by increasing pressure and decreasing flow rate; Step 3: In the variable water-cement ratio stage, when the pressure of the current slurry cannot be further increased or the flow rate reduced, switch to a slurry with a lower water-cement ratio and adjust the pressure and flow rate accordingly. Step 4: At the end of the grouting stage, maintain the design maximum pressure and low flow rate, and perform inversion analysis on the post-grouting formation permeability until the end criteria are met.

[0009] Preferably, in step 1, during the initial stage of grouting, the water-cement ratio and the initial grouting pressure or target flow rate are calculated based on the permeability of the borehole section, specifically including: Calculate the flow rate of the orifice section based on its permeability. Determine the upper and lower limits and average value of the grouting distance, and calculate the average flow velocity; Based on the characteristics of the selected slurry, the critical deposition rate is determined, and the parameter coefficients and target parameter set constants are calculated. Choose slurry for initial injection, determine the viscosity coefficient based on the initial water-cement ratio, and then determine the initial injection pressure or target flow rate.

[0010] Preferably, in step 2, during the single-stage grouting stage, the water-cement ratio is kept constant, and the product of pressure and flow rate is controlled to be a constant value by increasing pressure and decreasing flow rate, specifically: During the single-stage grouting stage, the water-cement ratio is kept constant, and the pressure and flow rate are set according to the principle of increasing pressure and decreasing flow rate and continuous control. As the grouting flow rate gradually decreases, the product of pressure and flow rate is kept constant by gradually increasing the grouting pressure.

[0011] Preferably, in step 3, during the variable water-cement ratio stage, when the pressure of the current slurry cannot be further increased or the flow rate decreased, the process switches to a slurry with a lower water-cement ratio, and the pressure and flow rate are adjusted accordingly. Specifically: When the pressure-flow relationship reaches a plateau, the system automatically switches to a slurry with a lower water-cement ratio. After switching, maintain or adjust the pressure and flow rate to ensure that the parameters conform to the effective deposition theory.

[0012] Preferably, in step 4, at the end of the grouting stage, the design maximum pressure and low flow rate are maintained, and the post-grouting formation permeability is analyzed by inversion until the end criteria are met, specifically: Maintain the design maximum pressure and control the flow rate to a stable low value; Post-irrigation formation permeability was analyzed based on Amenability theory. Grouting is considered complete when the permeability is lower than the design value.

[0013] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects: This invention provides a continuously variable grout pressure and grouting process intelligent control method. The method includes: in the initial grouting stage, calculating the starting pressure, target flow rate, and viscosity coefficient based on the borehole permeability; in the single-stage grouting stage, maintaining a constant water-cement ratio and controlling the product of pressure and flow rate to a constant value through pressure increase and flow decrease; in the variable water-cement ratio stage, when the current stage grout cannot be further pressurized or flow decreased, switching to a grout with a lower water-cement ratio and coordinating pressure and flow rate adjustments; in the final grouting stage, maintaining the designed maximum pressure and low flow rate, and inverting the analysis of post-grouting formation permeability until the termination criteria are met. This invention uses effective deposition theory as the core mathematical model, combined with real-time monitoring data, to achieve automated, intelligent, and full-process control, ensuring that the grout can deposit in the target area and effectively seal fractures. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 is a schematic diagram of the mathematical and physical model of bedrock fracture grout seepage in this invention. Figure 1a This is a schematic diagram of a borehole slab fracture grout diffusion model. Figure 1b (Schematic diagram of the seepage diffusion rheological model of fracture slurry). Figure 2 is a schematic diagram of the effective deposition parameter range of the present invention. Figure 2a A schematic diagram of the three-dimensional region for the effective sedimentation parameter set; Figure 2b for (Schematic diagram of the pressure-flow region for effective deposition under certain conditions). Figure 3 This is a schematic diagram showing the relationship between different stages of a typical grouting process according to the present invention; Figure 4 This is a schematic diagram of the process of the continuously variable grout pressure intelligent grouting control method provided in an embodiment of the present invention. Detailed Implementation

[0016] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] The purpose of this invention is to provide a fully intelligent grouting control method with stepless variable grout pressure. By using effective deposition theory as the core mathematical model and combining it with real-time monitoring data, it achieves automated, intelligent, and full-process control, ensuring that the grout can be deposited in the target area and effectively seal the cracks.

[0018] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0019] Before providing a detailed introduction to this invention, the relevant theoretical knowledge will first be introduced: 1. Mathematical physical model The process of cement grout seeping and diffusing into rock fissures through boreholes can be described using Bingham fluid Poiseuille flow based on a disk model, such as... Figure 1a and Figure 1b As shown, its flow characteristics are determined by two key rheological parameters of Bingham fluid: yield shear stress, and plastic viscosity, Its rheological equation can be expressed as:

[0020] When flow occurs, the pressure must overcome the yield stress, and a flow core region (with a height of [missing information]) will form in the fracture. Within this region, the fluid moves at a uniform velocity, sliding forward as a whole like a solid, resulting in a flat velocity distribution curve. In the shear zone between the core and the wall, the fluid undergoes shear deformation, with the velocity decreasing from the uniform value in the core to zero at the wall, exhibiting a parabolic velocity distribution. The pressure during the flow process... , and traffic Controlled by Poiseuille flow equations:

[0021] According to formula (2), the slurry flows and diffuses in the fracture, and eventually, under the design pressure conditions, the flow rate drops to or approaches zero. To achieve this goal, the average hydraulic clearance width of the fracture is... It should be related to the width of the flow core region. Gradually approaching, until Therefore, the entire fissure grouting process can be divided into three stages: In the first stage, the average hydraulic gap width of the fissure gradually decreases, the flow core zone expands, and the flow resistance increases; In the second stage, when the fissure opening decreases to be equal to the height of the flow core zone, the grout stops flowing relative to the entire fissure cross-section, like a continuous "solid plug," indicating that the fissure space has been completely filled with grout; In the third stage, the grouting pressure (screwing pressure) is maintained, and its function is no longer to promote the flow of grout, but to squeeze and drain the grout that has filled the fissure, so that the grout in the fissure gradually becomes thicker and denser, eventually forming a hardened stone with high strength and good impermeability.

[0022] 2. Effective Sedimentation Theory The theory of effective grout deposition is the main innovation of this invention and the theoretical basis for subsequent whole-process control strategies. It represents a significant advancement in the field of bedrock fracture grouting. Starting from first principles, it profoundly reveals the essence of successful grouting: the effectiveness of grouting does not simply depend on the amount of grout injected, but rather on whether cement particles can be stably retained within the target fracture area, thereby efficiently achieving permanent fracture closure. This theory posits that there exists a critical deposition velocity for grout flow within fractures. When the local flow velocity of the grout is lower than this threshold, cement particles will be filtered out of the grout and deposited on the surface of the crack. This deposition will directly reduce the effective opening of the crack, change the flow field distribution, and form a positive feedback mechanism—the smaller the opening, the greater the flow resistance, and the further the flow velocity, thereby accelerating the deposition of more particles. It is this "effective retention" process that triggers the irreversible closure process of the crack, which constitutes the physical basis for the effectiveness of the entire crack grouting.

[0023] Based on this mechanism, the effective deposition theory constructs its mathematical expression and control criteria. Its model derivation is derived from the radial flow motion equation of Bingham fluid in a flat plate fracture, and the controllable engineering parameters (pressure, flow rate) are linked with the slurry properties (water-cement ratio / shear stress of slurry on the fracture wall) through the force balance relationship, as shown in formula (3):

[0024] From the above formula, we can obtain:

[0025] in, This represents the distance the slurry diffuses. To ensure effective deposition, the slurry seepage parameters should meet the following requirements:

[0026] Substituting equation (4) into the above equation, we get:

[0027] To ensure the slurry is in the target area ( If sedimentation occurs, the parameters of the grouting slurry should meet the following requirements:

[0028] Formula (7) provides clear theoretical guidance for grouting construction: the core control objective of the grouting process should not only be to achieve the final pressure or flow rate value, but also to actively adjust parameters such as pressure, flow rate, and water-cement ratio throughout the grouting process, and maintain the grout flow rate within the critical deposition flow rate range, so as to efficiently and controllably promote crack closure, thereby significantly improving the reliability and efficiency of the grouting project. According to formula (7), the following can be drawn: Figure 2a The effective sedimentation parameter set shown in the three-dimensional region is as follows: Taking the water-cement ratio as an example, the parameter range of its effective grouting pressure and flow rate is as follows: Figure 2b As shown, this region is the same as the grouting parameter region specified by the three-zone, five-segment method. However, the three-zone, five-segment method is only a special case under the condition of constant water-cement ratio, while the three-dimensional parameter region specified by this method is more comprehensive, providing a theoretical basis for continuously variable pitch. It should be noted that... Figure 2b Only with Taking the slurry as an example, under actual working conditions, for any... The values ​​of each parameter have an effective pressure and flow rate combination range.

[0029] The grouting process for a single borehole section can generally be divided into four stages: the initial grouting stage, the single-stage grouting stage, the variable water-cement ratio stage, and the final grouting stage. Figure 3 As shown, it is important to note that changing the water-cement ratio is an operation. If a single water-cement ratio cannot meet the grouting requirements, it is necessary to change the water-cement ratio. However, if the water-cement ratio initially set for grouting can meet the requirements for crack sealing, grouting can be carried out with a single water-cement ratio until the end, that is, it is not necessary to change the water-cement ratio. The pressure-flow-water-cement ratio control strategies for these four grouting stages will be discussed below. It should be noted that only two of the three parameters of pressure, flow rate and water-cement ratio can be actively controlled. Therefore, the so-called control strategy is actually to determine the water-cement ratio of the grout and the grouting pressure or target flow rate.

[0030] Figure 4 This is a schematic diagram of the process of the continuously variable grouting and pressure-controlled intelligent grouting method provided in an embodiment of the present invention, as shown below. Figure 4 As shown, this invention provides a fully intelligent grouting control method with continuously variable grout pressure, comprising: Step 1: In the initial stage of grouting, calculate the starting pressure, target flow rate, and viscosity coefficient based on the permeability of the borehole section; Step 2: In the single-stage grouting stage, keep the water-cement ratio constant and control the product of pressure and flow rate to a constant value by increasing pressure and decreasing flow rate; Step 3: In the variable water-cement ratio stage, when the pressure of the current slurry cannot be further increased or the flow rate reduced, switch to a slurry with a lower water-cement ratio and adjust the pressure and flow rate accordingly. Step 4: At the end of the grouting stage, maintain the design maximum pressure and low flow rate, and perform inversion analysis on the post-grouting formation permeability until the end criteria are met.

[0031] In step 1, during the initial stage of grouting, the water-cement ratio and the initial grouting pressure or target flow rate are calculated based on the permeability of the borehole section. Specifically, this includes: The control strategy for the initial stage of grouting aims to determine the water-cement ratio and grouting pressure (or target flow rate) based on the permeability of the borehole section. The parameter settings should follow the principles of "low pressure, stable flow, and thin grout". The first step is to determine the permeability of the pore section. The flow rate of the orifice section is calculated as follows:

[0032] in, The permeability value of the perforated section is the Lü Rong value. The flow rate is calculated based on the orifice length (in meters). The unit is ; The second step is to calculate the flow velocity and determine the upper and lower limits of the grouting distance based on the design requirements of the grouting curtain. and and the average grouting distance, The average water velocity in the pressure test can be derived from formula (2):

[0033] The third step involves calculating the parameter coefficients and target parameter set constants, and determining the critical deposition rate based on the characteristics of the selected slurry (usually ordinary cement). Then the parameter coefficients can be calculated:

[0034] The constants of the target parameter set can be calculated from the parameter coefficients:

[0035] The fourth step is to calculate the target parameter set for grouting. Generally, a thin slurry is selected for grouting first, and the viscosity coefficient is determined by the water-cement ratio (for example, the viscosity coefficient of a slurry with a water-cement ratio of 1.3:1 is approximately...). The starting pressure or target flow rate can be determined by satisfying the following formula:

[0036] It should be noted that this irrigation parameter combination ( , , The purpose is to preliminarily assess the groutability of fractures and provide a benchmark for parameter control in subsequent stages, thereby creating initial conditions for effective grout deposition.

[0037] In step 2, during the single-stage grouting stage, the water-cement ratio is kept constant, and the product of pressure and flow rate is controlled to a constant value by increasing pressure and decreasing flow rate. Specifically: During the single-stage grouting stage, the water-cement ratio remains constant. The pressure and flow rate settings should follow the principle of "increasing pressure and decreasing flow rate, continuous control." As the grouting flow rate gradually decreases, the grouting pressure is gradually increased to maintain the product of pressure and flow rate at a constant value. Specifically, when the water-cement ratio of ordinary cement grout is greater than 0.7:1, the relationship between pressure and flow rate should satisfy formula (12); when the water-cement ratio of ordinary cement grout is less than 0.7:1, the relationship between pressure and flow rate should satisfy the following formula:

[0038] Here, The yield strength of the slurry. For a given value, its magnitude can be determined by the grouting parameters of the previous water-cement ratio. It should be noted that formula (12) and formula (13) are not different in principle, both being based on the effective deposition theory. However, the rheological control parameters (viscosity coefficient in slurry) are different during the flow of slurry with different water-cement ratios. Dominant, yield shear stress in thick slurry The core objective of the single-stage grouting parameter combination is to trigger the deposition effect using the grout with the current water-cement ratio: if the pressure steadily increases and the flow rate naturally decreases, it indicates that the grout of this stage is effectively closing the cracks; if the pressure-flow relationship remains unchanged for a long time, it indicates that the current water-cement ratio can no longer play a further effective role and the grouting change procedure needs to be initiated.

[0039] In step 3, during the variable water-cement ratio stage, when the pressure of the current slurry cannot be further increased or the flow rate decreased, the process switches to a slurry with a lower water-cement ratio, and the pressure and flow rate are adjusted accordingly. Specifically: During the water-cement ratio change stage, the pressure and flow rate settings must be closely coordinated with the thickening action of the water-cement ratio. When the current grout cannot be further pressurized or reduced, it should be switched to a thicker grout with a lower water-cement ratio (such as changing from 1:1 to 0.8:1 or 0.6:1). Simultaneously, the grouting pressure should be appropriately increased or the current pressure level should be maintained to compensate for the flow resistance caused by the increase in grout viscosity, and to stabilize or reduce the target flow rate. The quantitative control of the entire grout change process still needs to comply with the provisions of formulas (12) and (13), which correspond to the grout change under the conditions of thin grout (water-cement ratio above 0.7:1) and thick grout (water-cement ratio below 0.7:1), respectively. If the crack sealing has started (pressure increases or flow rate decreases) during the previous single-stage grouting process, but the sealing speed is not fast enough, the grout change carried out in order to improve the crack sealing speed should maintain the above formula. and The value remains unchanged; if, during the previous single-stage grouting process, fissure sealing has not yet begun (pressure and flow rate remain unchanged or change only slightly), in order to trigger the deposition of grout particles and the fissure sealing process, the value in the above formula should be appropriately reduced during the grouting process. and Value. This strategy of "reducing flow and stabilizing pressure, and continuing to inject thick grout" aims to stimulate an effective fracture closure response by increasing the concentration of grout particles and deposition efficiency, thereby promoting the transition of the grouting process to the final stage.

[0040] In step 4, at the end of the grouting process, the design maximum pressure and low flow rate are maintained, and the post-grouting formation permeability is analyzed through inversion until the completion criteria are met. Specifically: At the end of the grouting stage, the pressure, flow rate, and water-cement ratio should be set according to the principle of "high-pressure grouting and low-flow stabilization," and it is generally necessary to maintain the current water-cement ratio and maximum design pressure of the single-stage grouting. The parameters are kept constant, and the flow rate is reduced to an extremely low level and maintained for a certain period of time (generally 30 minutes). The core purpose of this parameter combination is to, on the basis that the fractures have been basically filled, use continuous high pressure to squeeze the grout, remove excess water, promote the consolidation and compaction of the grout, and form a high-strength, low-permeability stone body. The sign of the end stage is that the flow rate remains stable at the lower limit value under continuous high pressure for a long time, indicating that the fractures are fully closed, the grouting target has been achieved, and grouting can be terminated. Therefore, the core of parameter control in this stage is to determine the final flow rate of grouting. This method uses the Amenability theory to perform inverse analysis on the formation permeability at the end stage, which is:

[0041] The sign that grouting has reached its final stage is The permeability of the formation after irrigation is less than the design permeability.

[0042] This invention provides an embodiment that details the above method. Taking the intelligent grouting control of a bedrock curtain grouting borehole section in a large-scale water conservancy project in Northwest my country as an example, the specific application of the strategy is illustrated in detail, including the designed borehole depth of this section. The designed post-irrigation permeability rate is The designed grouting pressure is The grouting material is ordinary cement; Step 1: In the initial stage of grouting, calculate the starting pressure, target flow rate, and viscosity coefficient based on the permeability of the borehole section: Step 1.1: Water Pressure Test Based on the borehole section pressure test, the Lv Rong value was measured. Calculate the pressurized water flow rate: Step 1.2: Determine the slurry diffusion distance and average flow velocity Based on the engineering design hole spacing of 2 meters, the upper and lower limits of slurry diffusion are determined as follows: and Take the average value Drilling radius Viscosity of water The average flow velocity during water pressure is estimated according to formula (9): Step 1.3: Determine the parameter coefficients Through experimental determination, the critical deposition rate of cement grout in the rock fractures of this project was selected as [value missing]. The parameter coefficients can be calculated using formula (10): Step 1.4: Determine the starting parameters Based on the parameter coefficients, the target parameter set constants can be calculated according to formula (11): The initial water-cement ratio was determined to be 1.3:1, and its viscosity coefficient was [missing value]. Then the pressure and flow control parameters can be calculated according to formula (12): The initial injection pressure can be set to 0.5. MPa The target traffic is 17 L / min .

[0043] Step 2: During the single-stage grouting stage, maintain a constant water-cement ratio and control the product of pressure and flow rate to a constant value by increasing pressure and decreasing flow rate. Step 2.1: Control Execution Using intelligent grouting equipment, real-time pressure and flow control during a single-stage grouting process is achieved through programmable logic circuits (PLCs). The grouting pump and automatic control system operate according to the principle of "pressure increase and flow decrease, continuous control" to maintain... The value is stabilized around 0.041, and the system automatically adjusts accordingly. Step 2.2: Process Response After grouting begins, real-time monitoring shows that the flow rate begins to decrease naturally and slowly under pressure. The system automatically calculates and increases the pressure according to formula (12) to maintain the flow rate. The values ​​are relatively constant. It should be noted that due to the accuracy of data acquisition, the pressure and flow data collected once per second are not stable and will fluctuate within a narrow range. Therefore, the process control response is generally based on the average data per minute and is executed once per minute. Step 2.3: Effect Assessment At this stage, the pressure and flow rate show the expected inverse linkage, indicating that the 1.3:1 grout is effectively flowing in the fracture and starting to trigger the deposition effect. The fracture aperture is decreasing, but the rate of change of pressure and flow rate is not fast enough, which may require a long pure grouting time and waste more material. Therefore, it is necessary to carry out grouting adjustment to accelerate the grouting process.

[0044] Step 3: During the variable water-cement ratio stage, when the pressure or flow rate of the current slurry cannot be further increased or decreased, switch to a slurry with a lower water-cement ratio, and adjust the pressure and flow rate accordingly. Step 3.1: Pitch Shift Decision After 30 minutes of single-stage grouting, the intelligent grouting equipment detected that the pressure-flow relationship had plateaued: the pressure rose slowly after reaching 1.2 MPa, and the flow rate dropped slowly to 10 L / min. This indicated that the current water-cement ratio (1.3:1) of the grout had reached its maximum deposition efficiency, requiring a thicker grout to accelerate crack closure. Based on the strategy, the control system automatically decided to change the grout to a water-cement ratio of 0.7:1. Looking up the table, the rheological properties of the new grout were still determined by the viscosity coefficient (…). )control; Step 3.2: Parameter Coordination After switching to the new first-level grout, the pressure and flow control formula remains formula (12). The constants of the previous-level grouting parameters can be obtained from the calculation. After using the new grade 1 slurry water-cement ratio, the pressure and flow rate should meet the following requirements: The system adopts a "flow reduction and pressure stabilization" mode switching: while switching the grout, the grouting pressure is maintained at 1.2MPa and the target flow rate is maintained at 6L / min; Step 3.3: Continued Grouting Using intelligent grouting equipment, the addition of raw grout (generally with a water-cement ratio of 0.5:1) to the storage tank is automatically controlled, and the water-cement ratio of the grout in the storage tank is monitored in real time through a density sensor. Using the modified grout and pressure and flow parameters, the single-stage grouting operation in step 2 is executed.

[0045] Step 4: At the end of the grouting stage, maintain the design maximum pressure and low flow rate, and perform inversion analysis on the post-grouting formation permeability until the completion criteria are met. Step 4.1: Termination condition judgment As per the specifications, the pressure gradually increases to the maximum design pressure as grouting progresses. Traffic continued to drop to less than Once the pressure stabilizes and meets the end criteria, maintain the pressure for 30 minutes to complete the screen plastering operation. Step 4.2: Post-irrigation formation permeability analysis Flow rate at the screen stage The permeability of the formation after grouting was analyzed by inversion, and the grouting effect was evaluated. According to formula (14), the characteristic value of the formation after grouting was calculated as follows: It should be noted that the Lvrong value of the stratum calculated here does not take into account the subsequent cementitious bonding process of the cement grout to form a stone body, so it is a conservative estimate. The actual permeability of the bottom layer after grouting should be lower than this data.

[0046] The parameters provided by the present invention are shown in Table 1.

[0047] Table 1 Parameter List

[0048] The relationship between formula (7) and the practical application of grouting control strategies: In the grouting construction of borehole sections, the three parameters that can be controlled are pressure ( ),flow( The water-cement ratio, where pressure and flow rate are easy to understand, represents the concentration of the slurry (the mass ratio of water to ash). The water-cement ratio affects the rheological properties of the slurry (i.e., in formula (1)). and The rheological properties of the grout ultimately affect the shear stress between the grout and the fracture wall (i.e., the value). Therefore, it can be used. To characterize the change in the water-cement ratio of the slurry, controlling the water-cement ratio is to control... It is important to note that It cannot be directly measured; in subsequent practice, it needs to be based on measurable parameters. and Calculated ; Based on the above explanation, formula (7) gives the upper and lower boundary conditions that the grouting parameters (pressure-flow rate-water-cement ratio) must satisfy. This prevents the grout from settling too quickly, which would result in insufficient grouting distance; This prevents the grout from settling too slowly, which would result in excessively long grouting distances and wasted materials. Therefore, formula (7) provides the basic theory for controlling grouting parameters; However, in actual grouting construction, due to the use of intelligent grouting equipment, the control of pressure, flow rate, and water-cement ratio can be achieved to a considerable degree. Therefore, in actual construction, the following formula is used: That is, to The value is controlled between the upper and lower limits. Therefore, in formula (9), it is necessary to calculate the pressure test value. water flow velocity at the location And calculate this water flow velocity in formula (10). With the target water flow velocity The ratio relationship, it should be emphasized here that, in fact, the most important function of formula (7) is to prove that, in order to achieve effective deposition, It must be within a certain defined range, in practice. It needs to be a certain constant value Nearby fluctuations, in short Theoretically, it should be a constant value; And because It cannot be measured directly and requires estimation. The estimation result is: in a thin slurry, A constant value can be equivalent to It is a constant value; in thick slurry, A constant value can be equivalent to Let it be a constant value, thus obtaining formula (12) and formula (13).

[0049] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0050] Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A full-process intelligent grouting control method of stepless slurry pressure change, characterized in that, The method comprises the following steps: Step 1: In the initial stage of grouting, the initial grouting water-cement ratio and the initial grouting pressure or the target flow rate are calculated according to the permeability of the hole section; Step 2: In the single-stage grouting stage, the water-cement ratio is kept unchanged, and the product of the pressure and the flow rate is kept constant by increasing the pressure and decreasing the flow rate; Step 3: In the variable water-cement ratio stage, when the current grouting slurry cannot be further increased in pressure or decreased in flow rate, the grouting slurry with a lower water-cement ratio is switched to, and the pressure and the flow rate are adjusted coordinately; Step 4: In the end stage of grouting, the designed maximum pressure and the low flow rate are maintained, the permeability of the stratum after grouting is analyzed reversely until the end criterion is met.

2. The method of claim 1, wherein, In step 1, in the initial stage of grouting, the initial grouting water-cement ratio and the initial grouting pressure or the target flow rate are calculated according to the permeability of the hole section, which specifically comprises the following steps: The flow rate of the hole section is calculated according to the permeability of the hole section; The upper limit, the lower limit and the average value of the grouting distance are determined, and the average flow rate is calculated; The critical deposition velocity is determined according to the characteristics of the selected grouting material, and the parameter coefficient and the target parameter group constant are calculated; The initial grouting is performed with a dilute slurry, the viscosity coefficient is determined according to the initial grouting water-cement ratio, and the initial grouting pressure or the target flow rate is determined.

3. The method of claim 2, wherein, In step 2, in the single-stage grouting stage, the water-cement ratio is kept unchanged, and the product of the pressure and the flow rate is kept constant by increasing the pressure and decreasing the flow rate, which specifically comprises the following steps: In the single-stage grouting stage, the water-cement ratio is kept unchanged, and the product of the pressure and the flow rate is kept constant by increasing the pressure and decreasing the flow rate according to the principle of increasing the pressure and decreasing the flow rate and continuous control.

4. The method of claim 3, wherein, In step 3, in the variable water-cement ratio stage, when the current grouting slurry cannot be further increased in pressure or decreased in flow rate, the grouting slurry with a lower water-cement ratio is switched to, and the pressure and the flow rate are adjusted coordinately, which specifically comprises the following steps: When the pressure-flow rate relationship enters the plateau stage, the grouting slurry with a lower water-cement ratio is automatically switched to; After the switching, the pressure and the flow rate are maintained or adjusted to ensure that the parameters meet the effective deposition theory.

5. The method of claim 4, wherein, In step 4, in the end stage of grouting, the designed maximum pressure and the low flow rate are maintained, the permeability of the stratum after grouting is analyzed reversely until the end criterion is met, which specifically comprises the following steps: The designed maximum pressure is maintained, and the flow rate is controlled to a stable low value; The permeability of the stratum after grouting is analyzed reversely based on the amenability theory; When the permeability is lower than the designed value, the grouting is determined to be ended.

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