Grouting geology grading and construction parameter setting method based on rock mass permeability

Abstract

The invention provides a grouting geology grading and construction parameter setting method based on rock mass permeability, and relates to the technical field of foundation engineering grouting construction.The method comprises the steps that the water permeability rate, fracture parameters (the number of independent unfilled fractures, the opening degree and the filling condition), ground stress and grout rheology data of a target hole section are obtained; calculating a grouted stratum grouting index (SGI) through the water permeability rate, the fracture number, the maximum equivalent fracture opening degree and the correction coefficient; the rock splitting strength is estimated in combination with the drilling condition; whether grouting is conducted or not is judged based on the SGI value, and the grouting starting water cement ratio, the grout changing strategy, the initial pressure and the pressure increasing strategy are dynamically adjusted; the grouting pressure is designed according to the stratum splitting strength, and the grouting termination condition is set in combination with the real-time flow-pressure data. Grouting parameters are optimized through quantitative grading and real-time data, experience dependence is reduced, the construction precision and efficiency are improved, the stratum adaptability is enhanced, and the engineering quality and the material utilization rate are ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of grouting construction in foundation engineering, and particularly to a method for grouting geological classification and construction parameter setting based on rock mass permeability. Background Art

[0002] In foundation engineering construction, curtain grouting is an important method to improve the integrity of rock mass and reduce the permeability of bedrock. The groutability of the grouted formation directly determines the grouting effect, and accurate evaluation of the groutability of the formation helps to optimize the grouting process. However, traditional formation evaluation methods mainly rely on geological exploration data, such as borehole sampling, core analysis, and geophysical surveys. For the geological condition evaluation of foundation engineering, methods such as rock mass quality classification (RQD), surrounding rock grade (RMR), and rock integrity index (GSI) are widely used in China to evaluate the engineering properties of rock mass. RQD calculates the number of rock fractures per meter from core sampling data to reflect the degree of rock mass fragmentation. The higher the value, the better the integrity of the rock mass. The RMR rock mass classification system grades the surrounding rock by combining factors such as rock strength, RQD value, and gap width, and is used for the design of underground engineering. In addition, the GSI method evaluates the rock mass quality by observing the rock structure and weathering degree on site, and is widely used in underground tunnels and slope engineering. However, these traditional rock evaluation methods mostly describe the overall fracture density and fragmentation of rocks, adopt relatively single parameters, and are not targeted at a specific type of project. At present, there is still a blank in the geological rating method for grouting projects, especially for bedrock curtain grouting projects. Grouting construction, as an important technical means for improving basic geological conditions, urgently needs a geological rating method that conforms to its own construction characteristics.

[0003] For bedrock grouting projects, in recent years, scholars at home and abroad have proposed methods to evaluate the groutability of the formation through water pressure tests and local grouting tests. The literature "Construction and design of cement grouting" proposed a permeability classification method based on the Lugeon value of the water pressure test to evaluate the permeability of rock mass. In addition, the literature "Grouting technology in rock engineering" studied the penetration behavior of grout under different pressure conditions and established a grout diffusion model based on hydrodynamics. In actual engineering, some scholars use a combination of borehole water pressure tests and grouting tests to evaluate the permeability of the formation. However, grouting engineering practice shows that the influencing factors of formation groutability are very complex and there are many related parameters, making it difficult to obtain through a single water pressure data. More importantly, at present, optimizing the grouting strategy based on the geological conditions of the grouted formation still relies on subjective judgment based on on-site engineering experience, and a grouting construction strategy based on a unified groutability index has not been established. Summary of the Invention

[0004] To overcome the deficiencies of the prior art, the objective of the present invention is to provide a grouting geological classification and construction parameter setting method based on rock mass permeability, which can quantitatively evaluate the groutability of the formation, combine various parameters such as formation boundary conditions, and guide the grouting construction strategy.

[0005] To achieve the above objective, the present invention provides the following solutions:

[0006] A grouting geological classification and construction parameter setting method based on rock mass permeability, comprising:

[0007] Obtaining the measurement data of the target construction hole section; the measurement data includes the formation water permeability, rock mass fracture parameters, formation stress boundary conditions, and slurry rheological property data; the rock mass fracture parameters include: the number of independent unfilled fractures, the apparent aperture of the fractures and the filling situation;

[0008] Calculating the grouting index SGI of the grouted formation according to the measurement data; the formula for the grouting index of the grouted formation is: where q is the formation water permeability, m G is the number of independent unfilled fractures, b i is the apparent aperture of the fracture, k is the correction coefficient, b GM2 is the maximum equivalent fracture aperture of the hole section, and the calculation formula for the maximum equivalent fracture aperture of the hole section is: b max is the maximum fracture aperture;

[0009] Estimating the rock splitting strength according to the drilling conditions of the target construction hole section;

[0010] Determining whether to grout, the initial water-cement ratio, the slurry change strategy, the initial pressure, and the pressure increase strategy according to the grouting index SGI of the grouted formation;

[0011] Designing the grouting pressure according to the rock splitting strength;

[0012] Setting the grouting end condition according to the flow-pressure data obtained in real time.

[0013] Preferably, obtaining the measurement data of the target construction hole section includes:

[0014] Determining the formation water permeability of the rock mass by injecting water into the drilling of the target construction hole section and measuring the water penetration rate;

[0015] Using borehole imaging technology to capture the fracture traces on the borehole wall, and combining an automatic image processing algorithm to extract the rock mass fracture parameters;

[0016] Obtaining the formation stress boundary conditions through groundwater head measurement and in-situ stress estimation;

[0017] During the construction process, the rheological property data of the slurry are monitored in real time; the rheological property data of the slurry include: slurry temperature and water-cement ratio.

[0018] Preferably, the calculation formula for the apparent opening of the crack is:

[0019]

[0020] Preferably, estimating the rock splitting strength according to the drilling conditions of the target construction hole section includes:

[0021] If the drilling process of the target construction hole section is carried out by a geological drill integrated with a downhole sensor, the uniaxial compressive strength is calculated by the Bourgoyne formula to estimate the rock splitting strength; the calculation formula for the rock splitting strength is: wherein, k1, k2 and k3 are all empirical coefficients, WOB is the drilling pressure, ROP is the drilling speed, RPM is the bit rotation speed, and σ t is the rock splitting strength;

[0022] If the drilling process of the target construction hole section does not use an intelligent geological drill or the regression analysis of the grouting splitting pressure and the downhole drilling parameters is not carried out before construction, the rock splitting strength of the strata in this hole section is estimated according to the formation burial depth and groundwater conditions of the grouting hole section; the calculation formula for the rock splitting strength is: σ t =(0.47 - 0.02BI)·(σ v - p w )≈0.5(σ v - p w ); wherein, p w and σ v respectively represent the groundwater pressure and the maximum principal stress, and BI represents the rock brittleness index, which is used to describe the boundary conditions of the grouting formation.

[0023] Preferably, when the maximum principal stress measurement condition is not available, the maximum principal stress is estimated by the burial depth; the calculation formula for the maximum principal stress is: σ v =γHK0; wherein, H is the burial depth, γ is the rock unit weight, and K0 is the coefficient of lateral earth stress.

[0024] Preferably, determining whether to grout, the initial water-cement ratio, the slurry change strategy, the initial pressure and the pressure increase strategy according to the grouting index SGI of the grouted formation includes:

[0025] If the grouting index SGI of the grouted formation ≤ 1, no grouting is carried out;

[0026] If 1 < grouting index SGI of the grouted formation ≤ 1.3, in principle, no grouting is carried out;

[0027] If the grouting index SGI of the grouted formation > 1.3, perform grouting;

[0028] When the grouting index SGI of the grouted formation is higher, control the starting water-cement ratio to be lower;

[0029] Adopt step-by-step slurry variation, from low-concentration to high-concentration slurry;

[0030] When the grouting index SGI of the grouted formation is higher than the preset value, adopt a low starting pressure and slowly increase the pressure. When the grouting index SGI of the grouted formation is lower than the preset value, adopt a high starting pressure and quickly increase the pressure.

[0031] Preferably, the grouting end condition includes that the grouting flow rate per unit time ≤ 1 L / min and lasts for 5 minutes.

[0032] A grouting geological grading and construction parameter setting system based on rock mass permeability, comprising:

[0033] A data acquisition unit for acquiring measurement data of the target construction hole section; the measurement data includes formation water permeability, rock mass fracture parameters, formation stress boundary conditions, and slurry rheological property data; the rock mass fracture parameters include: the number of independent unfilled fractures, fracture apparent aperture, and filling condition;

[0034] An index calculation unit for calculating the grouting index SGI of the grouted formation according to the measurement data; the formula for the grouting index of the grouted formation is: wherein, q is the formation water permeability, m G is the number of independent unfilled fractures, b i is the fracture apparent aperture, k is a correction coefficient, b GM2 is the maximum equivalent fracture aperture of the hole section, and the calculation formula for the maximum equivalent fracture aperture of the hole section is: b max is the maximum fracture aperture;

[0035] A strength estimation unit for estimating the rock splitting strength according to the drilling conditions of the target construction hole section;

[0036] A grouting strategy formulation unit for determining whether to grout, starting water-cement ratio, slurry variation strategy, initial pressure, and pressure increase strategy according to the grouting index SGI of the grouted formation;

[0037] A pressure design unit for designing the grouting pressure according to the rock splitting strength;

[0038] An end condition determination unit for setting the grouting end condition according to the real-time acquired flow-pressure data.

[0039] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0040] The present invention evaluates the groutability of the formation in real time based on construction data, overcomes the limitation of traditional methods that only rely on initial geological exploration data, and improves the accuracy of evaluation; directly optimizes grouting parameters through SGI, reduces the dependence on personal experience judgment, and improves construction precision; obtains permeability and borehole fracture image data using conventional construction data; construction parameters can be queried in a standardized manner, enabling construction personnel or intelligent grouting equipment to quickly adjust the grouting strategy based on the SGI value, improving construction efficiency; enhances the adaptability of grouting construction to different formation conditions and optimizes construction quality; dynamically adjusts the grouting strategy based on real-time data, improves grouting efficiency and material utilization rate, and ensures construction efficiency and effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0042] Figure 1 It is a flowchart of the method provided by the embodiment of the present invention;

[0043] Figure 2 It is a schematic diagram of the technical route provided by the embodiment of the present invention;

[0044] Figure 3 It is an example diagram of digital core for grouting of construction hole sections provided by the embodiment of the present invention;

[0045] Figure 4 It is a parameter diagram of the grouting construction strategy partition provided by the embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0046] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0047] The purpose of the present invention is to provide a method for grouting geological classification and construction parameter setting based on rock mass permeability, which can quantitatively evaluate the groutability of the formation, combine various parameters such as formation boundary conditions, and guide the grouting construction strategy.

[0048] In order to make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below in conjunction with the drawings and specific embodiments.

[0049] Figure 1 This is the flowchart of the method provided by the embodiments of the present invention. As Figure 1 shown, the present invention provides a method for grouting geological classification and construction parameter setting based on the permeability of rock mass, including:

[0050] Step 100: Obtain the measurement data of the target construction hole section; the measurement data includes the formation water permeability, rock mass fracture parameters, formation stress boundary conditions, and slurry rheological property data; the rock mass fracture parameters include: the number of independent unfilled fractures, the apparent aperture of fractures and the filling situation;

[0051] Step 200: Calculate the grouting index SGI of the grouted formation according to the measurement data; the formula for the grouting index of the grouted formation is: where q is the formation water permeability, m G is the number of independent unfilled fractures, b i is the apparent aperture of fractures, k is the correction coefficient, b GM2 is the maximum equivalent fracture aperture of the hole section, and the calculation formula for the maximum equivalent fracture aperture of the hole section is: b max is the maximum fracture aperture;

[0052] Step 300: Estimate the rock splitting strength according to the drilling conditions of the target construction hole section;

[0053] Step 400: Determine whether to grout, the initial water-cement ratio, the slurry change strategy, the initial pressure, and the pressure boosting strategy according to the grouting index SGI of the grouted formation;

[0054] Step 500: Design the grouting pressure according to the rock splitting strength;

[0055] Step 600: Set the grouting end condition according to the flow-pressure data obtained in real time.

[0056] The core content of the present invention is to propose a grouting index for the grouted formation (Seepage-based Grouting Index, SGI) to evaluate the groutability of the formation in a quantitative manner. The technical solution adopted by the present invention to solve the technical problem can be divided into three steps. As Figure 2 shown, the technical roadmap of the technical solution is described in detail as follows:

[0057] Step 1: Data collection

[0058] Step 1.1: As Figure 3 shown, collect rock mass fracture and water permeability data

[0059] Rock mass fissures and water permeability are key factors affecting grouting performance. Water permeability data is mainly obtained through water pressure testing, which is a standard operating procedure in grouting engineering construction. This test determines the permeability of the rock mass by injecting water into the borehole and measuring the water penetration rate. The permeability of the rock mass is closely related to the rock mass fissure data, which is obtained through borehole photography. High-resolution borehole imaging technology is used to capture the traces of the hole wall cracks, and combined with automatic image processing algorithms to extract crack parameters such as the number of cracks, center point location, occurrence, opening, filling condition, etc. These parameters can be used to calculate the degree of development of the cracks and provide basic data for the subsequent grouting index calculation.

[0060] Step 1.2: Collect formation stress boundary data

[0061] The geostress environment of the stratum and the groundwater environment directly affect the diffusion and permeability behavior of the slurry. The present invention obtains the stratum stress boundary conditions by measuring the groundwater head and estimating the geostress. The groundwater head is data that must be measured during on-site construction and can be determined by observing the water level in the borehole. Geostress is usually difficult to measure directly, but it can be estimated based on the stratum depth, lithology and regional geostress field. In combination with existing geological data and engineering experience, the present invention uses an empirical formula to calculate the geostress, and corrects it in combination with the data measured on site to ensure the rationality of the stratum stress boundary conditions.

[0062] Step 1.3: Collect slurry rheological properties data

[0063] The rheological properties of the slurry play a vital role in the grouting effect. The present invention focuses on collecting two key parameters: the water-cement ratio of the slurry and the slurry temperature. The water-cement ratio determines the fluidity and permeability of the slurry, while the temperature affects the setting time and viscosity change of the slurry. By real-time monitoring of the slurry temperature during the construction process and combining the water-cement ratio adjustment strategy, the slurry ratio can be optimized to ensure its groutability under different formation conditions.

[0064] Step 2: Grouting geological classification

[0065] Step 2.1: Calculate the grouting index (SGI)

[0066] Grouting geological classification is mainly achieved through the grouting index (SGI) of the grouting formation, which comprehensively considers the permeability of the formation and the characteristics of the rock mass fractures, and adopts a weighted calculation method to ensure the scientificity and rationality of the evaluation results. Among them, the formation permeability index (SI) can be expressed as the following formula (1):

[0067]

[0068] Where q is the formation permeability (unit: Lu), obtained by water pressure test, and the upper limit of q is limited to 147Lu; mG It is the number of independent unfilled fissures in the hole section, obtained by automatic analysis and recognition of borehole images, and its upper limit is 24. It should be noted that the formation grouting index is positively correlated with the permeability rate. However, under the condition of the same permeability rate, the formation grouting index is negatively correlated with the number of independent fissures. The larger the number of fissures, the more the formation fissure network should be described as consisting of a large number of small non-absorbing fissures. Therefore, the weighted formation permeability rate index in the present invention is smaller.

[0069] Since microfissures contribute less to the grouting process, the bedrock grouting process is mainly manifested as the slurry entering the 1 - 2 fissures with the largest aperture in the formation. Therefore, it is necessary to consider the maximum aperture of the fissures contained in the hole section formation for grouting geological classification. The present invention calculates the maximum equivalent fissure aperture of the formation through formula (2):

[0070]

[0071] Among them, b i represents the apparent aperture of each single fissure identified in the borehole image of the hole section, and the unit of the apparent aperture is taken as mm; b max is the maximum fissure aperture obtained from the geological exploration borehole sampling. After homogenization processing, the value range of the maximum equivalent fissure aperture of the formation is between 0 and 5.

[0072] Combining SI and b GM2 , the present invention proposes the grouting index (SGI) of the grouted formation, and its expression formula is as follows:

[0073]

[0074] Among them, k is a correction coefficient, which characterizes the spatial trend of formation discontinuity, and its value is related to the engineering geological properties and needs to be obtained through on-site tests during the geological exploration stage; q and m G are parameters related to the formation permeability rate, as described in formula (1); b GM2 is the maximum equivalent fissure aperture of the hole section, as described in formula (2).

[0075] Step 2.2: Calculate the formation splitting strength

[0076] According to the formation stress boundary conditions, the formation splitting strength can be calculated, and this calculated value is crucial for the involved grouting pressure. The present invention proposes two sets of calculation methods for the formation splitting strength for the construction practice of grouting projects, including the calculation method based on the downhole data during drilling and the estimation method based on the formation burial depth and groundwater conditions.

[0077] If the drilling process is carried out using a geological drill integrated with downhole sensors, the uniaxial compressive strength can be calculated through the Bourgoyne formula, and then the rock splitting strength can be estimated, as shown in formula (4):

[0078]

[0079] Among them, k1, k2, and k3 are empirical coefficients, which can generally be obtained by fitting experimental data; WOB is the drilling pressure of the borehole, with the unit of kN, reflecting the pressure of the drill bit on the rock and indirectly affecting splitting; ROP is the drilling speed of the borehole, with the unit of m / hr. The faster the drilling speed, the softer the rock usually is and the lower the splitting strength; RPM is the rotational speed of the drill bit, with the unit of r / min.

[0080] If an intelligent geological drill is not used during the drilling process, or a regression analysis of the grouting splitting pressure and the drilling-with-parameter is not carried out before construction, the present invention can still estimate the splitting strength of the rock mass in the strata of this borehole section according to the formation burial depth and groundwater conditions of the grouting hole section. The formula is expressed as follows:

[0081] σ t =(0.47 - 0.02BI)·(σ v -p w )≈0.5(σ v -p w )

[0082] Among them, p w and σ v represent the groundwater pressure and the maximum principal stress respectively, and BI represents the rock brittleness index, which is used to describe the boundary conditions of the grouting formation. In engineering practice, when the condition for measuring the maximum principal stress is not available, the maximum principal stress is estimated through the burial depth, and its formula is expressed as:

[0083] σ v =γHK0

[0084] Among them, H is the burial depth; γ is the unit weight of the rock, generally taken as 25 - 30 kN / m 3 ; K0 is the coefficient of lateral earth stress, and its value varies in different rock masses, generally taken as 0.4 - 1.0, which is determined based on the engineering geological situation.

[0085] The core of the SGI theory is the seepage field and the stress field. Its main parameters respectively reflect the water permeability of the borehole section corrected by the fracture density, the groutability of a single fracture under the condition of a fracture group, and the splitting strength of the rock mass in the borehole section. Among them, the water permeability parameter occupies a higher weight because it directly reflects the seepage capacity of the formation. The fracture situation of the borehole section is summarized as the number of independent fractures and the maximum equivalent fracture width during the calculation process, which can correct the difference between the water permeability of the borehole section and the groutability and accurately reflect the influence of the formation structure on the slurry diffusion. The formation stress boundary parameters and slurry rheological property parameters collected in Step 1 will be used for the optimization of the automatic grouting strategy in Step 3, that is, the optimized initial parameters for the construction of this section can be obtained before grouting.

[0086] All the SGI theory consists of objective and quantitative geological parameters, which can be obtained through normal on-site operations and are independent of the personal experience of front-line operators. Its value can exclude the interference of human factors to the greatest extent. Also, since the geological conditions of the bedrock affected by the grouting body are actually discontinuous and tendentious, if expressed by a simple mathematical formula, a correction coefficient k needs to be set to enhance the universality of SGI. The SGI proposed this time targets the bedrock fracture groups and can be slightly extended to special situations such as karst caves, solution fissures, and fault fracture zones, showing the potential to become a general model for bedrock grouting.

[0087] Step 3: Develop a grouting construction strategy

[0088] As Figure 4 shown, based on the calculated SGI rating value, develop a reasonable grouting construction strategy to optimize the grouting efficiency and effect. The development of the construction strategy mainly includes the following aspects:

[0089] Step 3.1: Determine whether to grout

[0090] Based on the SI value and b GM2 value in the SGI theory, it can be determined whether to grout, which is specifically divided into the following situations:

[0091] If q ≤ 3Lu and m G ≥ 1, then SI ≤ 1. At this time, if b GM2 ≤ 1, then SGI ≤ 1. Its engineering meaning is that for the hole section with a permeability of 3Lu under the condition of a single fracture, no grouting is required;

[0092] If 3Lu ≤ q ≤ 5Lu and m G ≥ 1, then 1 < SI ≤ 1.3. At this time, let b GM2 = 1, then 1 < SGI ≤ 1.3. Its engineering meaning is that for the hole section with a permeability between 3Lu and 5Lu under the condition of a single fracture, in principle, no grouting is required;

[0093] If q > 5Lu and m G = 1, then SI > 1.3. At this time, let b GM2 = 1, then SGI > 1.3, and grouting should be carried out;

[0094] To sum up, grouting is not required under the condition of SGI ≤ 1, and grouting is not required in principle when 1 < SGI ≤ 1.3 (to be determined according to specific circumstances), and grouting should be carried out when SGI > 1.3. For the hole sections that should be grouted, the selection of the grouting construction strategy should follow the requirements of steps 3.2 - 3.6.

[0095] Step 3.2: Determine the initial water-cement ratio

[0096] When the SGI rating is high, the formation is more groutable and is suitable for a lower initial water-cement ratio so that it can fill the fractures more effectively. When the SGI rating is low, the initial water-cement ratio needs to be increased to increase the rheology of the slurry and improve the permeability of the slurry.

[0097] Step 3.3: Determine the pitch change strategy

[0098] During the construction process, combined with the SGI rating and real-time monitoring of flow-pressure data, the water-cement ratio and admixture content can be dynamically adjusted to make the slurry performance more suitable for the formation conditions. For formations with uneven fissure development, it is recommended to adopt a step-by-step slurry strategy, that is, first use low-concentration slurry for initial filling, and then use high-concentration slurry to increase the filling density.

[0099] Step 3.4: Determine initial pressure and boost strategy

[0100] For formations with high SGI ratings, a lower initial pressure can be used and the pressure can be increased slowly (with a reduced water-cement ratio) to avoid premature leakage of slurry along major fractures; for formations with low SGI ratings, a higher initial pressure should be used and the pressure increase rate should be adjusted according to the change in grouting volume to ensure sufficient diffusion of the slurry.

[0101] Step 3.5: Determine the design grouting pressure

[0102] When the pressure is gradually increased during the grouting process, a sudden change will occur when the formation splitting pressure P0 is reached. At this time, the grouting pressure can be adjusted according to the adaptive grouting method. The maximum (design) grouting pressure should be controlled at P0+(0.2~0.5)MPa until the end standard is reached.

[0103] Step 3.6: Determine the end conditions of grouting

[0104] Based on the initial calculated value of the SGI rating and the real-time data during the construction process, the appropriate termination criteria are determined, such as the grouting pressure is stable within a certain range and the grouting flow rate per unit time drops to a certain threshold. Combined with on-site monitoring, if the slurry penetration rate is significantly reduced or the pressure continues to increase, it is judged that the grouting effect has reached the expected level and the grouting can be terminated.

[0105] As an optional implementation method, the following will take the specific construction hole section data of a large-scale water conservancy project as an example to specifically illustrate the implementation process of this method:

[0106] Step 1: Obtain relevant construction and geological parameters for a specific construction hole section. The data collection process can be achieved through intelligent grouting equipment and integrated hole measurement equipment, and automatically uploaded to the intelligent grouting data platform. The data can be measured in the following three steps:

[0107] Step 1.1: Determine the water permeability rate of the rock mass in the hole section through a water pressure test, identify the fracture parameters using borehole camera imaging, automatically analyze the number of fractures, aperture width, intersection conditions, etc. through image technology, and generate a grouting digital core based on previous research results, and summarize the geological information of the hole section, such as Figure 2 The typical grouting hole section digital core data is shown as follows. A total of 5 independent fractures are found, and the water permeability rate is 22.86 Lu;

[0108] Step 1.2: Determine the formation boundary conditions by measuring the groundwater head and calculating the in-situ stress. According to the depths of the above two typical grouting hole sections, the estimated splitting strengths of the formation rock masses in the hole sections are 2 MPa respectively;

[0109] Step 1.3: Collect the water-cement ratio and slurry temperature, monitor and optimize the slurry mix ratio in real time to improve the injectability.

[0110] Step 2: Calculate the SI value and b GM2 values of the above hole section to be 1.3 and 3 respectively based on the water permeability rate data of the rock mass in the hole section obtained in Step 1 and the fracture analysis data from borehole camera imaging, and the designed grouting pressure of this hole section can be estimated to be 2.4 MPa.

[0111] Step 3: Develop a grouting strategy based on the SGI value and the designed grouting pressure of the hole section;

[0112] Step 3.1: Based on the SGI value, determine whether grouting is required for the hole section. Taking the above hole section as an example, its SGI value is 3.9, and grouting must be carried out. Its grouting parameters are determined through Steps 3.2 to 3.6;

[0113] Step 3.2: Based on Figure 3 determine that the initial water-cement ratio for hole section B is 5:1;

[0114] Step 3.3: Based on Figure 3 determine to adopt a strategy of gradually changing the slurry ratio, and successively use slurries with water-cement ratios of 3:1, 2:1, 1:1, and 0.5:1;

[0115] Step 3.4: According to Step 2, determine that the designed grouting pressure for this hole section is 2.4 MPa;

[0116] Step 3.5: Based on Figure 3 determine that the initial grouting pressure for the hole section is 0.48 MPa, and its pressure increase strategy is to gradually increase the pressure to the designed grouting pressure of the hole section, that is, use a grouting pressure of 0.48 MPa for the 5:1 water-cement ratio, 0.96 MPa for the 3:1 water-cement ratio, 1.44 MPa for the 2:1 water-cement ratio, 1.92 MPa for the 1:1 water-cement ratio, and 2.40 MPa for the 0.5:1 water-cement ratio;

[0117] Step 3.6: According to the specifications, the controlled pressure grouting ending standard is adopted for this hole section, that is, for each level of water-cement ratio and grouting pressure, a maximum of 300 kg of ash material is grouted, and the ending standard for the grouting hole section is: a grouting flow rate of 1 L / min for 5 minutes.

[0118] The beneficial effects of the present invention are as follows:

[0119] The present invention overcomes the limitation of the traditional method that only relies on the initial geological exploration data, improves the evaluation accuracy; directly optimizes the grouting parameters through SGI, reduces the dependence on personal experience judgment, and improves the construction accuracy; obtains the permeability rate and borehole fracture image data by using conventional construction data; the construction parameters can be queried standardly, enabling construction personnel or intelligent grouting equipment to quickly adjust the grouting strategy according to the SGI value, improving the construction efficiency; enhances the adaptability of grouting construction to different formation conditions and optimizes the construction quality; dynamically adjusts the grouting strategy based on real-time data, improves the grouting efficiency and material utilization rate, and ensures the construction efficiency and effect.

[0120] In this specification, each embodiment is described in a progressive manner. The key point of each embodiment is to illustrate the differences from other embodiments. For the same or similar parts among the embodiments, reference can be made to each other.

[0121] In this article, specific examples are used to elaborate on the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A method for grouting geological classification and construction parameter setting based on the permeability of rock mass, characterized in that, Including: Obtaining measurement data of a target construction hole section; the measurement data includes formation water permeability, rock mass fracture parameters, formation stress boundary conditions, and slurry rheological property data; the rock mass fracture parameters include: the number of independent unfilled fractures, fracture apparent aperture, and filling condition; Calculate the grouting index SGI of the grouted formation based on the measured data; the formula for the grouting index of the grouted formation is: where q is the permeability of the formation, m G is the number of independent unfilled fractures, b i is the apparent aperture of the fracture, k is the correction coefficient, b GM2 is the maximum equivalent fracture aperture of the hole section, and the calculation formula for the maximum equivalent fracture aperture of the hole section is: b max is the maximum fracture aperture; Estimating the rock splitting strength according to the drilling conditions of the target construction hole section; Determining whether to grout, initial water-cement ratio, slurry changing strategy, initial pressure, and pressure boosting strategy according to the grouting index SGI of the grouted formation; Designing the grouting pressure according to the rock splitting strength; Setting the grouting end condition according to the flow-pressure data obtained in real time.

2. The grouting geological classification and construction parameter setting method based on the rock mass permeability according to claim 1, characterized in that, Obtaining measurement data of a target construction hole section, including: Determining the formation water permeability of the rock mass by injecting water into the drilling of the target construction hole section and measuring the water penetration rate; Using borehole imaging technology to capture the fracture traces on the hole wall and extracting the rock mass fracture parameters in combination with an automatic image processing algorithm; Obtaining the formation stress boundary conditions through groundwater head measurement and in-situ stress estimation; Monitoring the slurry rheological property data in real time during the construction process; the slurry rheological property data includes: slurry temperature and water-cement ratio.

3. The grouting geological classification and construction parameter setting method based on rock mass permeability according to claim 1, characterized in that, The calculation formula for the fracture apparent aperture is:

4. The grouting geological classification and construction parameter setting method based on rock mass permeability according to claim 1, characterized in that, Estimating the rock splitting strength according to the drilling conditions of the target construction hole section, including: If the drilling process of the target construction hole section is carried out using a geological drill integrated with a downhole sensor, the uniaxial compressive strength is calculated by the Bourgoyne formula to estimate the rock splitting strength; the calculation formula for the rock splitting strength is: where k1, k2, and k3 are all empirical coefficients, WOB is the drilling pressure, ROP is the drilling speed, RPM is the bit rotation speed, and σ t is the rock splitting strength; If the intelligent geological drill is not used in the drilling process of the target construction hole section, or the regression analysis of the grouting splitting pressure and the drilling parameters while drilling is not carried out before construction, the rock splitting strength of the formation of this hole section is estimated according to the formation burial depth and groundwater conditions of the grouting hole section; the calculation formula of the rock splitting strength is: σ t =(0.47 - 0.02BI)·(σ v - p w )≈0.5(σ v - p w ); where p w and σ v represent the groundwater pressure and the maximum principal stress respectively, and BI represents the rock brittleness index, which is used to describe the boundary conditions of the grouting formation.

5. The grouting geological classification and construction parameter setting method based on rock mass permeability according to claim 4, characterized in that When the maximum principal stress measurement condition is not available, the maximum principal stress is estimated through the burial depth; the calculation formula for the maximum principal stress is: σ v = γHK0; where H is the burial depth, γ is the unit weight of rock, and K0 is the coefficient of lateral earth pressure.

6. The grouting geological classification and construction parameter setting method based on the permeability of rock mass according to claim 1, characterized in that, Determining whether to grout, initial water-cement ratio, slurry changing strategy, initial pressure, and pressure boosting strategy according to the grouting index SGI of the grouted formation, including: If the grouting index SGI of the grouted formation ≤ 1, no grouting is carried out; If 1 < grouting index SGI of the grouted formation ≤ 1.3, generally no grouting is carried out; If the grouting index SGI of the grouted formation > 1.3, grouting is carried out; When the grouting index SGI of the grouted formation is higher, the initial water-cement ratio is controlled lower; Adopting step-by-step slurry changing, from low-concentration slurry to high-concentration slurry; When the grouting index SGI of the grouted formation is higher than the preset value, a low initial pressure is adopted and the pressure is increased slowly, and when the grouting index SGI of the grouted formation is lower than the preset value, a high initial pressure is adopted and the pressure is increased rapidly.

7. The grouting geological classification and construction parameter setting method based on the permeability of rock mass according to claim 6, characterized in that The grouting end condition includes that the grouting flow rate per unit time ≤ 1 L / min and lasts for 5 minutes.

8. A grouting geological grading and construction parameter setting system based on the permeability of rock mass, characterized in that, Including: A data acquisition unit for obtaining measurement data of a target construction hole section; the measurement data includes formation water permeability, rock mass fracture parameters, formation stress boundary conditions, and slurry rheological property data; the rock mass fracture parameters include: the number of independent unfilled fractures, fracture apparent aperture, and filling condition; An exponential calculation unit for calculating the grouting index SGI of the grouted formation according to the measurement data; the formula for the grouting index of the grouted formation is: where q is the permeability of the formation, m G is the number of independent unfilled fractures, b i is the apparent aperture of the fracture, k is the correction coefficient, b GM2 is the maximum equivalent fracture aperture of the hole section, and the calculation formula for the maximum equivalent fracture aperture of the hole section is: b max is the maximum fracture aperture; A strength estimation unit for estimating the rock splitting strength according to the drilling conditions of the target construction hole section; A grouting strategy formulation unit for determining whether to grout, initial water-cement ratio, slurry changing strategy, initial pressure, and pressure boosting strategy according to the grouting index SGI of the grouted formation; A pressure design unit for designing the grouting pressure according to the rock splitting strength; An end condition determination unit for setting the grouting end condition according to the flow-pressure data obtained in real time.

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