Method for treating karst cave pile foundation in karst area through grouting steel pipe piles

Abstract

The invention relates to the technical field of karst cave pile foundation construction, in particular to a method for treating a karst cave pile foundation in a karst area through grouting steel pipe piles. The method comprises the following steps: drilling according to a measurement position to form a pile hole; obtaining a filler of the karst cave foundation in the karst area, and detecting the filler of the karst cave foundation in the karst area to obtain parameter data; performing multi-scale evaluation on the stability of the karst foundation based on the parameter data to obtain an evaluation result; based on the evaluation result, the minimum grouting amount and the minimum grouting pressure needed when the karst foundation is grouted are determined; inputting the minimum grouting amount and the pressure used for grouting into the karst area karst cave stability prediction model, and outputting a karst cave stability prediction result; and whether grouting conditions are met or not is judged based on the karst cave stability prediction result, if yes, slurry is prepared for the karst cave in the karst area, and grouting is completed. When the karst cave pile foundation in the karst area is constructed, the construction safety and the mechanical property of the pile foundation can be improved.

Description

Technical Field

[0001] The invention relates to the technical field of cave pile foundation construction, and in particular to a method for processing cave pile foundations in karst areas by utilizing grouting steel pipe piles. Background Art

[0002] In karst areas with complex geology, the presence of caves poses a great challenge to pile foundation engineering. Caves usually have irregular shapes, are widely distributed, and are difficult to predict. These characteristics make it easy for piles to become unstable, collapse, leak, and other problems when constructing pile foundations in karst areas, which seriously affects the quality and safety of the project. Therefore, it is particularly important to develop an efficient and safe method for treating cave pile foundations in karst areas.

[0003] Traditional methods for pile foundation treatment in karst areas include backfilling with stone and grouting reinforcement, but these methods have exposed many limitations in practical applications. Although the backfilling with stone method is simple and easy to implement, it is not ideal for large caves or cave groups, and it is difficult to ensure the long-term stability of the pile foundation. Although the grouting reinforcement method can improve the bearing capacity of the foundation to a certain extent, when dealing with caves, it is easy to cause problems such as loose grouting and foundation settlement after grouting because the grouting material is difficult to completely fill the cavity in the cave.

[0004] In recent years, with the continuous development of construction technology, grouting steel pipe piles have gradually attracted attention as a new type of pile foundation treatment method. Grouting steel pipe piles combine the high bearing capacity of steel pipe piles and the advantages of grouting technology. By grouting into the steel pipe piles, the grouting material forms a uniform reinforcement layer around the pile body, thereby effectively improving the bearing capacity and stability of the pile foundation. In addition, grouting steel pipe piles also have good adaptability and flexibility, and can be adjusted and optimized according to different geological conditions and engineering requirements.

[0005] In the treatment of cave pile foundations in karst areas, the application of grouting steel pipe piles has significant advantages. First, grouting steel pipe piles can penetrate deep into the cave, fill and reinforce the cave with grouting materials, and effectively avoid the occurrence of problems such as pile instability and collapse. Secondly, the grouting materials of grouting steel pipe piles can be evenly distributed around the pile body to form a continuous reinforcement layer, thereby improving the overall bearing capacity and stability of the foundation. Finally, the construction process of grouting steel pipe piles is relatively simple, and the interference to the surrounding environment is small, which has good environmental protection and economic benefits.

[0006] In the prior art, there is a lack of a method for treating karst cave pile foundations in karst areas using grouting steel pipe piles. Summary of the invention

[0007] The purpose of the present invention is to provide a method for treating karst cave pile foundations by using grouting steel pipe piles: to solve the technical problem that in the existing scheme, when constructing karst cave pile foundations in karst areas, the occurrence of problems such as pile body instability and collapse cannot be effectively avoided, thereby resulting in low overall bearing capacity and stability of the foundation.

[0008] The purpose of the present invention can be achieved through the following technical solutions:

[0009] A method for treating a karst cave pile foundation in a karst area by using a grouting steel pipe pile, the method comprising:

[0010] Drill holes according to the measured positions to form pile holes;

[0011] Obtaining the filling material of the karst cave foundation in the karst area, and detecting the filling material of the karst cave foundation in the karst area to obtain parameter data;

[0012] Based on the parameter data, the stability of the karst foundation is evaluated at multiple scales to obtain the evaluation results;

[0013] Determine the minimum grouting volume and grouting pressure required for grouting karst foundation based on the evaluation results;

[0014] The minimum grouting volume and the pressure used for grouting are input into the karst cave stability prediction model, and the cave stability prediction result is output;

[0015] Based on the prediction results of cave stability, it is determined whether the grouting conditions are met. If so, slurry is prepared for the cave in the karst area to complete the grouting.

[0016] Furthermore, obtaining the filling material of the karst cave foundation in the karst area and detecting the filling material of the karst cave foundation in the karst area to obtain parameter data includes the following process:

[0017] Detecting the particle diameter of the filler to obtain the average diameter of the filler particles;

[0018] Taking the average diameter as the equivalent diameter of the filler particles, a hexagonal particle force equivalent model is established, where the hexagonal particle force equivalent model is a force equivalent model of six particles adjacent to each other.

[0019] The average stress and porosity of the filler particles are calculated based on the hexagonal particle force equivalent model, and the average stress and porosity are used as parameter data.

[0020] Furthermore, the calculation of the average stress of the filler particles based on the hexagonal particle force equivalent model includes the following process:

[0021] Establish a global coordinate system, obtain the local position of each filler particle, and obtain the distribution function ω(θ, φ, β) of the mesoscopic structure density based on the local position, where θ, φ, β are all Euler angles;

[0022] The average stress σ of the filler particles is calculated according to the correlation formula, which is as follows:

[0023] σ=∫∫∫ω(θ,φ,β)*P -1 MPsinφdθdφdβ

[0024] Among them, P -1 (·)P is the transposed matrix, M is the mesoscopic stress, M=(n, t, w), where n, t, and w are the mesoscopic stress direction vectors in the three directions of the global coordinate system,

[0025]

[0026] Furthermore, the calculation of the porosity ratio of filler particles based on the hexagonal particle force equivalent model specifically includes the following process:

[0027] Obtaining the mesoscopic stress structure of the filler particles in the global coordinate system and obtaining the initial mesoscopic structure angle α;

[0028] Calculate the volume V of the dodecahedron composed of the vectors of the mesoscopic structure 12 :

[0029]

[0030] Calculate the particle volume V of the filler s :

[0031]

[0032] Based on volume V 12 and volume V s Calculate the void ratio e0:

[0033]

[0034] Where d is the average diameter of the filler particles.

[0035] Furthermore, the stability of the karst foundation is evaluated at multiple scales based on the parameter data, and the evaluation results include the following processes:

[0036] Substituting the average stress and porosity ratio into the evaluation correlation formula, the stability coefficient WD of the karst foundation is obtained. The evaluation correlation formula is as follows:

[0037]

[0038] Among them, S is the diameter of the pile foundation, Y is the thickness of the steel casing, σ is the average stress, and e0 is the porosity ratio;

[0039] The stability coefficient WD of the karst foundation is recorded as the evaluation result.

[0040] Furthermore, the minimum grouting volume and grouting pressure required for grouting the karst foundation based on the evaluation results include the following process:

[0041] The karst foundation model corresponding to the stability coefficient WD of different karst foundations was tested by traditional triaxial compression test, and a result comparison table was obtained. The stability coefficient WD of different karst foundations in the result comparison table corresponds to the minimum grouting volume and pressure used for grouting.

[0042] Based on the evaluation results, the minimum grouting volume and grouting pressure required for grouting in karst foundation are queried.

[0043] Furthermore, the minimum grouting volume and the grouting pressure are input into the karst cave stability prediction model, and the output of the cave stability prediction result includes the following process:

[0044] The minimum grouting volume and the grouting pressure are input into the karst cave stability prediction model to obtain the cave stability prediction coefficient LMS. The calculation formula of the karst cave stability prediction model is as follows:

[0045]

[0046] Among them, R and E are constants, V B is the standard grouting volume, determined based on the volume of the grouting steel pipe pile, V MIN is the minimum grouting amount, P MAX is the maximum pressure value during grouting of grouting steel pipe piles, P Y The pressure used for grouting;

[0047] The cave stability prediction coefficient LMS is recorded as the cave stability prediction result.

[0048] Furthermore, judging whether the grouting conditions are met based on the cave stability prediction results includes:

[0049] The cave stability prediction coefficient threshold is loaded, and the cave stability prediction coefficient threshold is a preset value. It is determined whether the cave stability prediction coefficient LMS is greater than the cave stability prediction coefficient threshold. If so, it is determined that the grouting conditions are met, and if not, it is determined that the grouting conditions are not met.

[0050] Furthermore, the slurry preparation for the karst caves includes:

[0051] The slurry includes the following components in proportion by mass: 20% cement, 15% water, 45% fly ash, 8% chelating agent, 4% clay, 3% fly ash and 5% diatomaceous earth.

[0052] Compared with the existing solutions, the present invention achieves the following beneficial effects:

[0053] The present invention drills holes according to the measurement positions to form pile holes; obtains the filling material of the karst cave foundation in the karst area, and detects the filling material of the karst cave foundation in the karst area to obtain parameter data; performs multi-scale evaluation on the stability of the karst foundation based on the parameter data to obtain evaluation results; and analyzes the stability of the karst foundation to improve the overall bearing capacity and stability of the foundation when forming a pile foundation on the foundation.

[0054] In addition, based on the evaluation results, the minimum grouting volume and grouting pressure required for grouting in the karst foundation are determined; the minimum grouting volume and grouting pressure are input into the karst cave stability prediction model, and the cave stability prediction results are output; based on the cave stability prediction results, it is judged whether the grouting conditions are met. If so, the karst caves are equipped with slurry and grouting is completed, which can further improve construction safety and ensure construction efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0056] Figure 1 It is a flow chart of a method for treating a karst cave pile foundation in a karst area by using a grouting steel pipe pile according to an embodiment of the present invention;

[0057] Figure 2 It is a flow chart of another method for treating karst cave pile foundations in karst areas by using grouting steel pipe piles according to an embodiment of the present invention;

[0058] Figure 3 The present invention is another flowchart of a method for treating a karst cave pile foundation in a karst area by using grouting steel pipe piles according to an embodiment of the present invention. DETAILED DESCRIPTION

[0059] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions 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 are within the scope of protection of the present invention.

[0060] In addition, the described features, structures or characteristics may be combined in one or more example embodiments in any suitable manner. In the following description, many specific details are provided to provide a full understanding of the example embodiments of the present disclosure. However, those skilled in the art will appreciate that the technical solutions of the present disclosure may be practiced while omitting one or more of the specific details, or other methods, components, steps, etc. may be adopted. In other cases, well-known structures, methods, implementations or operations are not shown or described in detail to avoid obscuring various aspects of the present disclosure.

[0061] This embodiment provides a method for treating a karst cave pile foundation by using a grouting steel pipe pile. Figure 1 FIG. 1 is a flow chart of a method for treating a karst cave pile foundation in a karst area by using a grouting steel pipe pile according to an embodiment of the present invention. Figure 1 As shown, the method comprises the following steps:

[0062] Step S101, drilling according to the measurement position to form a pile hole;

[0063] Step S102, obtaining the filling material of the karst cave foundation in the karst area, and detecting the filling material of the karst cave foundation in the karst area to obtain parameter data;

[0064] Step S103, performing a multi-scale evaluation on the stability of the karst foundation based on the parameter data to obtain an evaluation result;

[0065] Step S104, determining the minimum grouting volume and grouting pressure required for grouting the karst foundation based on the evaluation result;

[0066] Step S105, judging whether the grouting conditions are met based on the cave stability prediction result, if yes, proceeding to step S106, if no, proceeding to step S107;

[0067] Step S106, preparing slurry for the karst caves to complete grouting;

[0068] Step S107, stop construction and reselect the measurement position.

[0069] In summary, the present invention drills holes according to the measurement position to form pile holes; obtains the filling material of the karst cave foundation, and detects the filling material of the karst cave foundation to obtain parameter data; based on the parameter data, the stability of the karst foundation is evaluated at multiple scales to obtain evaluation results; the stability of the karst foundation is analyzed to improve the overall bearing capacity and stability of the foundation when forming a pile foundation. Based on the evaluation results, the minimum grouting amount and grouting pressure required for grouting the karst foundation are determined; the minimum grouting amount and grouting pressure are input into the karst cave stability prediction model, and the cave stability prediction results are output; based on the cave stability prediction results, it is determined whether the grouting conditions are met. If so, the karst cave is equipped with slurry to complete the grouting, which can further improve the construction safety and ensure the construction efficiency.

[0070] In some embodiments, before step S101, the primary task of treating karst caves in pile foundation construction is to explore the pile foundation points, analyze the geological conditions of the location, and make preparations for construction in advance with relatively complete geological data. Before drilling holes in pile foundation construction, remember not to place overly heavy equipment near the hole to prevent construction losses caused by hole collapse. For the purpose of karst cave treatment, it is advisable to set up hoisting and hauling equipment of sufficient tonnage at the pile foundation construction site; if the pile foundation construction is carried out in water, the stability of the construction platform should also be considered.

[0071] In some embodiments, in step S102, Figure 2 FIG. 1 is a flow chart of another method for treating a karst cave pile foundation in a karst area by using a grouting steel pipe pile according to an embodiment of the present invention. Figure 2 As shown, the method comprises the following steps:

[0072] Step S201, detecting the particle diameter of the filler to obtain the average diameter of the filler particles;

[0073] Step S202, using the average diameter as the equivalent diameter of the filler particles, establishing a hexagonal particle force equivalent model, wherein the hexagonal particle force equivalent model is a force equivalent model of six particles adjacent to each other;

[0074] Step S203, calculating the average stress and porosity of the filler particles based on the hexagonal particle force equivalent model, and using the average stress and porosity as parameter data.

[0075] It is worth mentioning that in geotechnical engineering, material science or particle mechanics, when the average diameter is used to describe the particle size of the filler, it is usually to simplify the complex particle shape and size distribution. However, in order to conduct more accurate analysis or simulation, it is sometimes necessary to establish an equivalent model to represent these particles.

[0076] For the equivalent model of hexagonal particles, a regular hexagonal particle can be assumed, whose circumscribed circle has a diameter equal to the average diameter of the filler. This hexagonal particle can be used as a simplified model to analyze the behavior of particles under stress.

[0077] The following are the basic steps to establish a hexagonal particle force equivalent model:

[0078] Determine the average diameter: First, the average diameter of the filler needs to be determined. This can be done by measuring the diameter of a large number of particles and calculating their average. If the shape and size distribution of the particles is complex, more complex statistical methods may be needed to determine the average diameter.

[0079] Select Hexagon: Select a regular hexagon whose circumscribed circle has a diameter equal to the average diameter of the infill. This hexagon will serve as a representative of the equivalent model.

[0080] Force analysis: For hexagonal particles, the forces in different directions can be analyzed. Due to the symmetry of the hexagon, it can be assumed that it is subjected to uniformly distributed forces. These forces can be decomposed into normal forces and tangential forces along the hexagonal boundaries.

[0081] Establishing mechanical equations: Based on the force analysis, mechanical equations can be established to describe the stress state of hexagonal particles. These equations will include force balance equations, moment balance equations, and possible material constitutive equations (if material deformation is considered).

[0082] Solving mechanical equations: By solving mechanical equations, we can obtain the displacement, stress, strain and other parameters of hexagonal particles under stress. These parameters can be used to evaluate the mechanical properties and stability of fillers.

[0083] In some embodiments, calculating the average stress of filler particles based on the hexagonal particle force equivalent model includes the following process:

[0084] Establish a global coordinate system, obtain the local position of each filler particle, and obtain the distribution function ω(θ, φ, β) of the mesoscopic structure density based on the local position, where θ, φ, β are all Euler angles;

[0085] The average stress σ of the filler particles is calculated according to the correlation formula, which is as follows:

[0086] σ=∫∫∫ω(θ,φ,β)*P -1 MPsinφdθdφdβ

[0087] Among them, P -1 (·)P is the transposed matrix, M is the mesoscopic stress, M=(n, t, w), where n, t, and w are the mesoscopic stress direction vectors in the three directions of the global coordinate system,

[0088]

[0089] Furthermore, the calculation of the porosity ratio of filler particles based on the hexagonal particle force equivalent model specifically includes the following process:

[0090] Obtaining the mesoscopic stress structure of the filler particles in the global coordinate system and obtaining the initial mesoscopic structure angle α;

[0091] Calculate the volume V of the dodecahedron composed of the vectors of the mesoscopic structure 12 :

[0092]

[0093] Calculate the particle volume V of the filler s :

[0094]

[0095] Based on volume V 12 and volume V s Calculate the void ratio e0:

[0096]

[0097] Where d is the average diameter of the filler particles.

[0098] In some embodiments, performing a multi-scale evaluation on the stability of a karst foundation based on parameter data to obtain an evaluation result includes the following process:

[0099] Substituting the average stress and porosity ratio into the evaluation correlation formula, the stability coefficient WD of the karst foundation is obtained. The evaluation correlation formula is as follows:

[0100]

[0101] Among them, S is the diameter of the pile foundation, Y is the thickness of the steel casing, σ is the average stress, and e0 is the porosity ratio;

[0102] The stability coefficient WD of the karst foundation is recorded as the evaluation result.

[0103] In some embodiments, in step S104, Figure 3 FIG. 1 is a flow chart of another method for treating a karst cave pile foundation in a karst area by using a grouting steel pipe pile according to an embodiment of the present invention. Figure 3 As shown, the method comprises the following steps:

[0104] Step S301, using a traditional triaxial compression test to test the karst foundation model corresponding to the stability coefficient WD of different karst foundations, to obtain a result comparison table, in which the stability coefficient WD of different karst foundations corresponds to the minimum grouting amount and the pressure used for grouting in a one-to-one manner;

[0105] Step S302, based on the evaluation result, query the minimum grouting volume and grouting pressure required for grouting the karst foundation.

[0106] It is worth mentioning that the traditional triaxial compression test is used to evaluate the stability coefficient of different karst foundations. The following is a simplified example showing how to organize such a comparison table:

[0107]

[0108] In some embodiments, the minimum grouting volume and the grouting pressure are input into the karst cave stability prediction model, and the output of the cave stability prediction result includes the following process:

[0109] The minimum grouting volume and the grouting pressure are input into the karst cave stability prediction model to obtain the cave stability prediction coefficient LMS. The calculation formula of the karst cave stability prediction model is as follows:

[0110]

[0111] Among them, R and E are constants, V B is the standard grouting volume, determined based on the volume of the grouting steel pipe pile, V MIN is the minimum grouting amount, P MAX is the maximum pressure value during grouting of grouting steel pipe piles, P Y The pressure used for grouting;

[0112] The cave stability prediction coefficient LMS is recorded as the cave stability prediction result.

[0113] Furthermore, judging whether the grouting conditions are met based on the cave stability prediction results includes:

[0114] The cave stability prediction coefficient threshold is loaded, and the cave stability prediction coefficient threshold is a preset value. It is determined whether the cave stability prediction coefficient LMS is greater than the cave stability prediction coefficient threshold. If so, it is determined that the grouting conditions are met, and if not, it is determined that the grouting conditions are not met.

[0115] The preparation of slurry for karst caves includes:

[0116] The slurry includes the following components in proportion by mass: 20% cement, 15% water, 45% fly ash, 8% chelating agent, 4% clay, 3% fly ash and 5% diatomaceous earth.

[0117] The above embodiments can be implemented in whole or in part by software, hardware, firmware or any other combination. When implemented by software, the above embodiments can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions or computer programs. When the computer instructions or computer programs are loaded or executed on a computer, the process or function described in the embodiment of the present application is generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions can be transmitted from one website site, computer, server or data center to another website site, computer, server or data center by wired (e.g., infrared, wireless, microwave, etc.). The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that contains one or more available media sets. The available medium can be a magnetic medium (e.g., a floppy disk, a hard disk, a tape), an optical medium (e.g., a DVD), or a semiconductor medium. The semiconductor medium can be a solid-state hard disk.

[0118] Those of ordinary skill in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0119] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0120] In the several embodiments provided in the present application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the units is only some logical function divisions. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0121] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0122] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A method for treating karst cave pile foundations using grouting steel pipe piles, characterized in that the method include: Drill holes according to the measured positions to form pile holes; Obtaining the filling material of the karst cave foundation in the karst area, and detecting the filling material of the karst cave foundation in the karst area to obtain parameter data; Based on the parameter data, the stability of the karst foundation is evaluated at multiple scales to obtain the evaluation results; Determine the minimum grouting volume and grouting pressure required for grouting karst foundation based on the evaluation results; The minimum grouting volume and the pressure used for grouting are input into the karst cave stability prediction model, and the cave stability prediction result is output; Based on the prediction results of cave stability, it is determined whether the grouting conditions are met. If so, slurry is prepared for the cave in the karst area to complete the grouting.

2. A method for treating karst cave pile foundations in karst areas by using grouting steel pipe piles according to claim 1, characterized in that: Obtaining the filling material of the karst cave foundation in the karst area and detecting the filling material of the karst cave foundation in the karst area to obtain parameter data includes the following processes: Detecting the particle diameter of the filler to obtain the average diameter of the filler particles; Taking the average diameter as the equivalent diameter of the filler particles, a hexagonal particle force equivalent model is established, where the hexagonal particle force equivalent model is a force equivalent model of six particles adjacent to each other. The average stress and porosity of the filler particles are calculated based on the hexagonal particle force equivalent model, and the average stress and porosity are used as parameter data.

3. A method for treating karst cave pile foundations in karst areas by using grouting steel pipe piles according to claim 2, characterized in that: Calculation of the average stress of filler particles based on the equivalent model of hexagonal particles The process includes: Establish a global coordinate system, obtain the local position of each filler particle, and obtain the distribution function ω(θ, φ, β) of the mesoscopic structure density based on the local position, where θ, φ, β are all Euler angles; The average stress σ of the filler particles is calculated according to the correlation formula, which is as follows: σ=∫∫∫ω(θ,φ,β)*P -1 MPsinφdθdφdβ Among them, P -1 (·)P is the transposed matrix, M is the mesoscopic stress, M=(n, t, w), where n, t, and w are the mesoscopic stress direction vectors in the three directions of the global coordinate system, 4. A method for treating karst cave pile foundations in karst areas by using grouting steel pipe piles according to claim 3, characterized in that: The calculation of the void ratio of filler particles based on the hexagonal particle force equivalent model specifically includes the following process: Obtaining the mesoscopic stress structure of the filler particles in the global coordinate system and obtaining the initial mesoscopic structure angle α; Calculate the volume V of the dodecahedron composed of the vectors of the mesoscopic structure 12 : Calculate the particle volume V of the filler s : Based on volume V 12 and volume V s Calculate the void ratio e0: Where d is the average diameter of the filler particles.

5. The method for treating karst cave pile foundations in karst areas by using grouting steel pipe piles according to claim 2, characterized in that: The stability of karst foundation is evaluated at multiple scales based on parameter data, and the evaluation results include the following processes: Substituting the average stress and porosity ratio into the evaluation correlation formula, the stability coefficient WD of the karst foundation is obtained. The evaluation correlation formula is as follows: Among them, S is the diameter of the pile foundation, Y is the thickness of the steel casing, σ is the average stress, and e0 is the porosity ratio; The stability coefficient WD of the karst foundation is recorded as the evaluation result.

6. The method for treating karst cave pile foundations in karst areas by using grouting steel pipe piles according to claim 1, characterized in that: Determine the minimum grouting volume and grouting pressure required for grouting in karst foundation based on the evaluation results The process includes: The karst foundation model corresponding to the stability coefficient WD of different karst foundations was tested by traditional triaxial compression test, and a result comparison table was obtained. The stability coefficient WD of different karst foundations in the result comparison table corresponds to the minimum grouting volume and pressure used for grouting. Based on the evaluation results, the minimum grouting volume and grouting pressure required for grouting in karst foundation are queried.

7. The method for treating karst cave pile foundations in karst areas by using grouting steel pipe piles according to claim 1, characterized in that: The minimum grouting volume and grouting pressure are input into the karst cave stability prediction model, and the output of cave stability prediction results includes the following process: The minimum grouting volume and the grouting pressure are input into the karst cave stability prediction model to obtain the cave stability prediction coefficient LMS. The calculation formula of the karst cave stability prediction model is as follows: Among them, R and E are constants, V B is the standard grouting volume, determined based on the volume of the grouting steel pipe pile, V MIN is the minimum grouting amount, P MAX is the maximum pressure value during grouting of grouting steel pipe piles, P Y The pressure used for grouting; The cave stability prediction coefficient LMS is recorded as the cave stability prediction result.

8. The method for treating karst cave pile foundations in karst areas by using grouting steel pipe piles according to claim 7, characterized in that: Judging whether the grouting conditions are met based on the cave stability prediction results includes: The cave stability prediction coefficient threshold is loaded, and the cave stability prediction coefficient threshold is a preset value. It is determined whether the cave stability prediction coefficient LMS is greater than the cave stability prediction coefficient threshold. If so, it is determined that the grouting conditions are met, and if not, it is determined that the grouting conditions are not met.

9. The method for treating karst cave pile foundations in karst areas by using grouting steel pipe piles according to claim 1, characterized in that: The slurry prepared for the karst caves includes: the slurry includes the following components in proportion by mass: 20% cement, 15% water, 45% fly ash, 8% chelating agent, 4% clay, 3% fly ash and 5% diatomaceous earth.

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