Marine unfavorable geology reef limestone grouting strength prediction method based on pore structure

Abstract

The invention provides a marine unfavorable geology reef limestone grouting strength prediction method based on a pore structure. The method comprises the following steps: calculating a reef limestone rock pore value of a reef limestone rock pore volume accounting for a reef limestone rock mass volume; performing size classification on the equivalent diameters of the communicated pores in the reef limestone, and calculating the volume ratio of each type of communicated pores; calculating the pore sphericity of the pore particles according to the pore particle surface area and the pore particle volume; classifying the pore particles according to the pore sphericity, and calculating the sphericity ratio of each type of pore particles; calculating a seepage coefficient based on the pore value of the reef limestone rock, the volume ratio of various communicated pores and the sphericity ratio of various pore particles; calculating the flow of the slurry flowing in the reef limestone rock under the action of different pressures according to the seepage coefficient; and calculating the tensile strength of the reef limestone rock based on the flow before and after grouting. Through accurate permeability analysis, the construction risk and cost are reduced, and meanwhile the bearing capacity of the foundation base is improved.

Description

Technical Field

[0001] The invention relates to the technical field of reef limestone detection, and in particular to a method for predicting grouting strength of marine unfavorable geological reef limestone based on pore structure. Background Art

[0002] With the growth of global energy demand and the deepening of marine resource development, the stability issues of offshore wind power foundations, pile foundations of cross-sea bridges and offshore oil and gas production platforms in marine engineering have become increasingly prominent.

[0003] By predicting the compressive strength of reef limestone after grouting reinforcement, engineers can evaluate and ensure the foundation stability of marine structures such as offshore platforms, bridges, and docks. This is essential to prevent the structure from being damaged under extreme weather conditions or seabed geological changes. Accurate compressive strength prediction can help design more effective grouting schemes, optimize material use, reduce material waste, and shorten construction time. This has a direct impact on reducing project costs and improving construction efficiency. By optimizing the grouting reinforcement scheme, interference with the marine environment can be reduced, such as reducing the leakage of chemical materials during the grouting process and protecting the marine ecosystem.

[0004] As a common marine geological material, reef limestone has a complex pore structure and variable permeability. Traditional grouting methods are difficult to meet the growing engineering needs. Therefore, under adverse marine geological conditions, how to effectively predict and improve the grouting strength of reef limestone and develop a rapid identification and prediction method based on pore structure are of great significance to improving the safety, economy and environmental friendliness of marine engineering, and have become a technical problem that needs to be solved urgently in the field of marine engineering. Summary of the invention

[0005] The invention proposes a method for predicting the grouting strength of marine poor geological reef limestone based on pore structure, so as to solve the technical problem of how to effectively predict and improve the grouting strength of reef limestone under marine poor geological conditions.

[0006] In order to solve the above technical problems, the present invention provides a method for predicting the grouting strength of marine unfavorable geological reef limestone based on pore structure, comprising the following steps:

[0007] Step S11: calculating the reef limestone rock porosity value of the reef limestone rock pore volume to the reef limestone rock mass volume;

[0008] Step S12: classifying the equivalent diameters of the connected pores in the reef limestone, and calculating the volume proportion of each type of connected pores;

[0009] Step S13: calculating the pore sphericity of the porous particles according to the surface area and volume of the porous particles;

[0010] Step S14: classifying the porous particles according to the pore sphericity, and calculating the sphericity ratio of each type of porous particles;

[0011] Step S15: Calculating the permeability coefficient based on the porosity value of the reef limestone, the volume percentage of various types of connected pores, and the sphericity percentage of various types of pore particles;

[0012] Step S16: Calculate the flow rate of the slurry flowing in the reef limestone under different pressures through the seepage coefficient; calculate the tensile strength of the reef limestone based on the flow rate before and after grouting.

[0013] Preferably, the expression of step S11 is:

[0014]

[0015] In the formula, P is the porosity value of the reef limestone; V0 is the pore volume of the reef limestone; and V is the volume of the reef limestone.

[0016] Preferably, the expression of step S12 is:

[0017]

[0018] In the formula, E q1 、E q2 、E q3 、E q4 、E q5 are the proportion of small pores, relatively small pores, medium pores, relatively large pores and large pores in the pores of reef limestone rocks; V1, V2, V3, V4 and V5 are the pore volumes of small pores, relatively small pores, medium pores, relatively large pores and large pores respectively; V0 is the pore volume of reef limestone rocks.

[0019] Preferably, the expression of step S13 is:

[0020]

[0021] Where M is the sphericity of the pores; S is the surface area of ​​the pore particles; and v is the volume of the pore particles.

[0022] Preferably, the expression of step S14 is:

[0023]

[0024] Wherein, N1, N2, N3 and N4 are the proportions of flat, flat-square, spherical and spherical pore particles to the pores of reef limestone respectively; M1, M2, M3 and M4 are the volumes of flat, flat-square, spherical and spherical pore particles respectively; V0 is the pore volume of reef limestone.

[0025] Preferably, the expression of step S15 is:

[0026]

[0027] Where K is the seepage coefficient of the reef limestone; A, B, C and D are linear coefficients; P is the porosity value of the reef limestone; α i The proportion of connected pores classified by different equivalent diameters to the pore volume of reef limestone E qi- Correction coefficient of u is the sphericity ratio of various porous particles N u The correction coefficient is: n is the number of particles; R n is the pore throat radius of the nth particle in the reef limestone; b0 is the initial slip factor; μ T is the dynamic viscosity of the slurry at temperature T; p is the pore pressure; μ0 is the dynamic viscosity of the slurry at the reference temperature; T is the current temperature; T0 is the reference temperature; b is the temperature index.

[0028] Preferably, in step S16, the flow rate Q of the slurry flowing in the reef limestone under different pressures is calculated by the following expression:

[0029]

[0030] Where G is the cross-sectional area of ​​the rock during grouting, k1 is the pressure at the slurry inlet, k2 is the pressure at the slurry outlet, and L is the distance the slurry moves.

[0031] Preferably, in step S16, the expression for calculating the tensile strength of the reef limestone is:

[0032]

[0033] In the formula, Q S Q is the flow rate of reef limestone after grouting is completed; F is the flow rate of reef limestone before grouting; F S F is the compressive strength of reef limestone after grouting; F is the compressive strength of reef limestone before grouting; H is the independent variable coefficient; J is the intercept.

[0034] Preferably, the pore volume, equivalent diameter of connected pores, pore particle surface area and pore particle volume of the reef limestone rock are obtained by the following method:

[0035] Step S21: After sampling the reef limestone, scanning the reef limestone;

[0036] Step S22: segmenting the pores and solid phase using a threshold segmentation method;

[0037] Step S23: performing three-dimensional reconstruction on the segmented image to generate a three-dimensional model of the soil;

[0038] Step S24: construct a ball-and-stick model, in which the ball represents the porous particles and the stick represents the connectivity between the porous particles.

[0039] Preferably, the scanned data of the reef limestone are preprocessed, and the preprocessing includes denoising and contrast enhancement.

[0040] The beneficial effects of the present invention include at least: in actual marine engineering, such as offshore wind power foundations, pile foundations of cross-sea bridges, and the stability of offshore oil and gas production platforms, it is necessary to have an accurate understanding of the permeability of seabed reef limestone rocks. Through the calculation method based on pore structure of the present invention, the distribution of grouting materials can be predicted and optimized to improve the stability and durability of the structure. For example, in the construction of offshore wind farms, through accurate permeability analysis, a grouting scheme that is more suitable for local geological conditions can be designed, thereby reducing construction risks and costs, while improving the bearing capacity of wind power foundations. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 A schematic diagram of a method flow chart of an embodiment of the present invention;

[0042] Figure 2 Schematic diagram of a parameter acquisition method according to an embodiment of the present invention. DETAILED DESCRIPTION

[0043] The following is a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the protection scope of the present invention.

[0044] Example 1

[0045] like Figure 1 As shown, an embodiment of the present invention provides a method for predicting grouting strength of marine unfavorable geological reef limestone based on pore structure, comprising the following steps:

[0046] Step S11: Calculate the reef limestone rock porosity value of the pore volume of the reef limestone rock to the reef limestone rock mass volume.

[0047] Specifically, during the grouting process of marine adverse geological reef limestone, the rock permeability coefficient can reflect the slurry penetration effect during the grouting process, and the rock permeability coefficient depends on the pore structure inside the rock body.

[0048] Porosity value P is used to represent the poor geological reef limestone, and it is calculated according to the ratio of rock mass porosity to rock mass volume:

[0049]

[0050] In the formula: P is the porosity value of reef limestone, V0 is the pore volume of reef limestone, and V is the volume of reef limestone.

[0051] Step S12: classify the equivalent diameters of the connected pores in the reef limestone by size, and calculate the volume percentage of each type of connected pores.

[0052] Specifically, there are connected pores and isolated pores in the reef limestone pores. The existence of the connected pores ensures that the slurry can be injected and circulated in the pores, while the isolated pores cannot be injected with the slurry. q The size of the pores can be divided into five categories: small pores (0<E q ≤1mm), small pores (1mm<E q ≤2mm), medium pores (2mm<E q ≤3mm), larger pores (3mm<E q ≤4mm), macropores (E q >4mm), and then calculate the volume proportion of each type of connected pores.

[0053]

[0054] Where: E q1 、E q2 、E q3 、E q4 and E q5 are the proportions of small pores, relatively small pores, medium pores, relatively large pores and large pores in the pore volume of reef limestone rock, V1, V2, V3, V4 and V5 are the pore volumes of small pores, relatively small pores, medium pores, relatively large pores and large pores, respectively, and V0 is the pore volume of reef limestone rock.

[0055] Step S13: Calculate the pore sphericity of the porous particles by the surface area and volume of the porous particles.

[0056] Specifically, the porous particles of reef limestone have different shapes. The definition of sphericity is introduced, and the particle shape ranges from 0 to 1. 1 represents a perfect sphere, that is, the surface area and volume of the particle are exactly the same as those of a sphere of the same volume, which means that the shape of the particle is completely close to an ideal sphere. 0 means that the particle shape is the farthest from the sphere, usually extremely flat or elongated particles, such as flake or columnar particles. If the porous particles are closer to 1, the slurry is easier to flow, and its calculation expression is:

[0057]

[0058] Where: M is the sphericity of the pores, S is the surface area of ​​the pore particles, and v is the volume of the pore particles.

[0059] Step S14: classify the porous particles according to the pore sphericity, and calculate the sphericity ratio of each type of porous particles.

[0060] Specifically, in the embodiment of the present invention, the sphericity of the connected pore particles of the reef limestone is divided into flat type (0<M≤0.25), relatively flat type (0.25<M≤0.5), relatively spherical type (0.5<M≤0.75) and spherical reef limestone (0.75<M≤1), and the sphericity ratio of each pore particle is calculated.

[0061]

[0062] Where: N1, N2, N3 and N4 are the proportions of flat, flat-square, spherical and spherical pore particles to the pores of reef limestone, respectively; M1, M2, M3 and M4 are the volumes of flat, flat-square, spherical and spherical pore particles, respectively; V0 is the pore volume of reef limestone.

[0063] Step S15: Calculate the permeability coefficient based on the reef limestone rock porosity value, the volume percentage of various types of connected pores, and the sphericity percentage of various types of pore particles.

[0064] Specifically, the seepage coefficient K of the reef limestone rock mass is calculated as follows.

[0065]

[0066] In the formula, R n is the pore throat radius of the nth particle in the reef limestone, n is the number of particles; α i The proportion of connected pores classified by different equivalent diameters to the pore volume of reef limestone E qi- Correction coefficient of u is the sphericity ratio of various porous particles N u The correction coefficient of A, B, C and D are the pore value P and the volume proportion E of each type of connected pores. qi , the sphericity proportion of various types of porous particles is M u , the linear coefficient of the average pore throat radius in the reef limestone; b0 is the initial slip factor; μ T is the dynamic viscosity of the slurry at temperature T; p is the pore pressure, which represents the pressure acting on the slurry; μ0 is the dynamic viscosity of the slurry at the reference temperature; T is the current temperature; T0 is the reference temperature, usually 25°; b is the temperature index.

[0067] Step S16: Calculate the flow rate of the slurry flowing in the reef limestone under different pressures through the seepage coefficient; calculate the tensile strength of the reef limestone based on the flow rate before and after grouting.

[0068] Specifically, the flow rate of slurry flowing in reef limestone under different pressures is calculated by the following expression:

[0069]

[0070] Where G is the cross-sectional area of ​​the rock during grouting, k1 is the pressure at the slurry inlet, k2 is the pressure at the slurry outlet, and L is the distance the slurry moves.

[0071] The greater the slurry flow during grouting, the more volume of slurry remains in the reef limestone after grouting, which means the better the grouting reinforcement effect and the higher the compressive strength of the rock. The compressive strength of the reef limestone after grouting is calculated by the following formula to avoid re-sampling, prevent damage to the rock, and reduce disturbance.

[0072]

[0073] In the formula, Q S Q is the flow rate of reef limestone after grouting is completed; F is the flow rate of reef limestone before grouting; F S F is the compressive strength of reef limestone after grouting; F is the compressive strength of reef limestone before grouting; H is the independent variable coefficient; J is the intercept.

[0074] Example 2

[0075] This embodiment provides a method for parameter collection, which is mainly used to obtain the calculation parameters required in Embodiment 1.

[0076] Specifically, Figure 2 As shown in FIG. 1 , it mainly includes the following steps: after sampling the marine poor geological reef limestone, the reef limestone scanning data, such as CT scan or SEM image, is imported into the Avizo software by scanning the reef limestone. The imported image is preprocessed, including denoising, contrast enhancement, etc., to better distinguish the solid phase and pores of the reef limestone. The pores and solid phases are separated by the threshold segmentation method for subsequent analysis. The segmented image is reconstructed in three dimensions to generate a three-dimensional model of the soil. A ball-and-stick model is constructed to represent the reef limestone particles and pores, where the ball represents the particles and the stick represents the connectivity between the particles.

[0077] By using the ball-and-stick model to represent the model, all the parameters of the reef limestone rock required for Example 1 can be obtained.

[0078] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. Only the preferred embodiments of the present invention are expressed. The description is more specific and detailed, but it cannot be understood as limiting the scope of the present invention. As long as there is no contradiction in the combination of these technical features, they should be considered as within the scope of this specification.

[0079] It should be noted that, for those skilled in the art, several modifications and improvements can be made without departing from the concept of the present invention, and these modifications and improvements all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the attached claims.

Claims

1. A method for predicting grouting strength of marine unfavorable geological reef limestone based on pore structure, characterized by: The following steps are involved: Step S11: calculating the reef limestone rock porosity value of the pore volume of the reef limestone rock to the reef limestone rock mass volume; Step S12: classifying the equivalent diameters of the connected pores in the reef limestone, and calculating the volume proportion of each type of connected pores; Step S13: calculating the pore sphericity of the porous particles according to the surface area and volume of the porous particles; Step S14: classifying the porous particles according to the pore sphericity, and calculating the sphericity ratio of each type of porous particles; Step S15: Calculating the permeability coefficient based on the porosity value of the reef limestone, the volume percentage of various types of connected pores, and the sphericity percentage of various types of pore particles; Step S16: calculating the flow rate of the slurry flowing in the reef limestone under different pressures through the permeability coefficient; The tensile strength of the reef limestone rock was calculated based on the flow rates before and after grouting.

2. The method for predicting grouting strength of marine unfavorable geological reef limestone based on pore structure according to claim 1 is characterized by: The expression of step S11 is: In the formula, P is the porosity value of the reef limestone; V0 is the pore volume of the reef limestone; and V is the volume of the reef limestone.

3. The method for predicting grouting strength of marine unfavorable geological reef limestone based on pore structure according to claim 1 is characterized by: The expression of step S12 is: In the formula, E q1 、E q2 、E q3 、E q4 、E q5 are the proportion of small pores, relatively small pores, medium pores, relatively large pores and large pores in the pores of reef limestone rocks; V1, V2, V3, V4 and V5 are the pore volumes of small pores, relatively small pores, medium pores, relatively large pores and large pores respectively; V0 is the pore volume of reef limestone rocks.

4. The method for predicting grouting strength of marine unfavorable geological reef limestone based on pore structure according to claim 1 is characterized by: The expression of step S13 is: Where M is the sphericity of the pores; S is the surface area of ​​the pore particles; and v is the volume of the pore particles.

5. The method for predicting grouting strength of marine unfavorable geological reef limestone based on pore structure according to claim 1 is characterized by: The expression of step S14 is: Wherein, N1, N2, N3 and N4 are the proportions of flat, flat-square, spherical and spherical pore particles to the pores of reef limestone respectively; M1, M2, M3 and M4 are the volumes of flat, flat-square, spherical and spherical pore particles respectively; V0 is the pore volume of reef limestone.

6. The method for predicting grouting strength of marine unfavorable geological reef limestone based on pore structure according to claim 1 is characterized by: The expression of step S15 is: Where K is the seepage coefficient of the reef limestone; A, B, C and D are linear coefficients; P is the porosity value of the reef limestone; α i The proportion of connected pores classified by different equivalent diameters to the pore volume of reef limestone E qi- Correction factor of β u is the correction coefficient of the sphericity ratio Nu of various porous particles; n is the number of particles; R n is the pore throat radius of the nth particle in the reef limestone; b0 is the initial slip factor; μ T is the dynamic viscosity of the slurry at temperature T; p is the pore pressure; μ0 is the dynamic viscosity of the slurry at the reference temperature; T is the current temperature; T0 is the reference temperature; b is the temperature index.

7. The method for predicting grouting strength of marine unfavorable geological reef limestone based on pore structure according to claim 6 is characterized by: In step S16, the flow rate Q of the slurry flowing in the reef limestone under different pressures is calculated by the following expression: Where G is the cross-sectional area of ​​the rock during grouting, k1 is the pressure at the slurry inlet, k2 is the pressure at the slurry outlet, and L is the distance the slurry moves.

8. The method for predicting grouting strength of marine unfavorable geological reef limestone based on pore structure according to claim 7 is characterized by: In step S16, the expression for calculating the tensile strength of the reef limestone is: In the formula, Q S Q is the flow rate of reef limestone after grouting is completed; F is the flow rate of reef limestone before grouting; F S F is the compressive strength of reef limestone after grouting; F is the compressive strength of reef limestone before grouting; H is the independent variable coefficient; J is the intercept.

9. The method for predicting grouting strength of marine unfavorable geological reef limestone based on pore structure according to claim 1, characterized in that: The pore volume, equivalent diameter of connected pores, pore particle surface area and pore particle volume of the reef limestone are obtained by the following method: Step S21: After sampling the reef limestone, scanning the reef limestone; Step S22: segmenting the pores and solid phase using a threshold segmentation method; Step S23: performing three-dimensional reconstruction on the segmented image to generate a three-dimensional model of the soil; Step S24: construct a ball-and-stick model, in which the ball represents the porous particles and the stick represents the connectivity between the porous particles.

10. The method for predicting grouting strength of marine unfavorable geological reef limestone based on pore structure according to claim 9, characterized in that: The scanned data of the reef limestone are preprocessed, and the preprocessing includes denoising and contrast enhancement.

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