Device and method for preparing discontinuous rock slope model containing complex structural surface

Abstract

The invention provides a device and a method for preparing a discontinuous rock slope model containing a complex structural surface. The device comprises a random field modeling unit, a rock mass 3D printing modeling system, a data acquisition and monitoring unit and a negative pressure extraction unit. The method for preparing the discontinuous rock slope model containing the complex structural surface according to the device comprises the steps of three-dimensional random field modeling and data preparation, model printing, complex geological structure implementation, sacrificial material removal, final model forming and the like. According to the device, high-fidelity physical reproduction of a complex internal structure and spatial variability of a rock mass is realized. Geological exploration data is directly and accurately converted into a three-dimensional physical model, and the limitation of a traditional homogeneous model is broken through. The space variability of rock mass mechanical parameters can be quantitatively simulated by controlling the mix proportion and distribution of materials, so that a physical model is closer to a real engineering rock mass in the aspect of heterogeneous characteristics, and an unprecedented entity sample is provided for researching mechanical behaviors of heterogeneous rock masses.

Description

Technical Field

[0001] This invention relates to the field of geotechnical engineering model testing technology, and in particular to an apparatus and method for preparing a discontinuous rock slope model with complex structural surfaces. Background Technology

[0002] Rock masses are complex geological formations composed of rock material and various internal structural surfaces (such as joints, fissures, bedding, and weak interlayers). Compared to soil, natural rock masses undergo long and complex geological tectonic movements during their formation and evolution, resulting in significant spatial variability and their mechanical behavior being heavily controlled by the network of internal structural surfaces. This inherent heterogeneity and discontinuity cause rock masses, especially those in slope engineering, underground caverns, and tunnel engineering, to exhibit high uncertainty and potential instability under stress conditions, posing significant challenges to the design and construction of related projects.

[0003] To further study the mechanical properties and failure mechanisms of rock masses, scholars both domestically and internationally have conducted numerous rock mechanics experiments. Currently, research on the mechanical properties of intact, homogeneous rock samples is relatively in-depth, and a relatively mature theoretical and experimental system has been formed. However, experimental research on rock masses with complex internal structures (such as slope rock masses) that are closer to engineering practice is relatively scarce, mainly due to limitations in the preparation technology of existing physical models.

[0004] Currently, the main methods for preparing fractured rock mass samples include artificially pre-fabricated fracture methods, such as simulating fractures or weak interlayers by mechanically drilling, cutting, or embedding selected materials into standard rock specimens. These traditional methods can simulate simple fractures to some extent, but they generally suffer from the following significant shortcomings. These shortcomings directly lead to limitations in experimental observation results:

[0005] A. Existing technologies lack sufficient precision in controlling the spatial morphology and location of fractures. Machining methods struggle to precisely control the spatial distribution of non-penetrating fractures (such as tortuous or undulating fracture surfaces), and are even less capable of creating independently existing closed or open fractures within the specimen. Their control over the fracture's location, inclination angle, thickness, and other geometric parameters is limited, and the machining process easily damages the specimen.

[0006] B. Existing methods are insufficient in simulating the heterogeneity and complex structure of rock masses. Traditionally prepared samples are mostly homogeneous materials or contain only simple single fractures, failing to realistically reproduce the spatial variability of mechanical parameters in natural rock masses and the complex structural systems composed of multiple sets of fractures, weak interlayers, etc. Especially in simulating the gradual transition zones between different lithological units, existing technologies have significant shortcomings, often resulting in abrupt material interface bonding and sudden changes in mechanical properties, which do not conform to actual conditions.

[0007] C. Existing technologies struggle to quantitatively simulate the microstructure of rock masses. There are currently no effective physical models to represent the primary microporosity of rock masses and its key influence on seepage characteristics.

[0008] D. Because it is impossible to prepare a model with a clear and controllable internal structure, and the model material itself is usually opaque, it is difficult to observe the initiation, propagation and penetration of internal cracks in real time and without damage during the experiment, which restricts the in-depth understanding of the failure mechanism of rock mass.

[0009] Therefore, developing devices and methods for preparing discontinuous rock slope models with complex structural surfaces has become an urgent need in the field of rock mechanics experimental research. Summary of the Invention

[0010] The purpose of this invention is to provide an apparatus and method for preparing a discontinuous rock slope model with complex structural surfaces, so as to solve the problems existing in the prior art.

[0011] The technical solution adopted to achieve the purpose of this invention is as follows: a device for preparing a discontinuous rock slope model with complex structural surfaces, including a random field modeling unit, a rock mass 3D printing modeling system, a data acquisition and monitoring unit, and a negative pressure extraction unit.

[0012] The random field modeling unit is used to generate a three-dimensional heterogeneous rock mass model that characterizes the spatial variability of rock mass parameters based on random field theory.

[0013] The rock mass 3D printing modeling system includes a main control unit, a material storage device, a material mixing port, a multi-axis linkage printing platform, and a scanning device. The main control unit is connected to the material mixing port, the multi-axis linkage printing platform, and the scanning device. The material storage device is connected to an intelligent adjustable nozzle via the material mixing port. The material mixing port integrates multiple independently numbered supply compartments, including a P01 port for supplying basic photosensitive resin, a P02 port for supplying toughening resin, a P03 port for supplying reinforcing filler, a P04 port for supplying regulating filler, a P05 port for supplying photoinitiator, a P06 port for supplying functional additives, an S01 port for supplying hollow glass microspheres, and a Sac port for supplying sacrificial material. The intelligent adjustable nozzle has a central mixing chamber and input channels corresponding to the aforementioned ports. The multi-axis linkage printing platform can move in the X, Y, and Z directions and has rotation functions along the A and B axes, allowing the nozzle to approach the printing surface at a non-perpendicular angle and deposit material along complex inclined surfaces. After material ejection, the scanning device selectively scans and solidifies the area excluding the sacrificial material trajectory according to instructions from the main control unit. The main control unit is configured to: receive a 3D digital model from the random field modeling module; parse the 3D digital model into spatially continuously varying material mixing ratio instructions and printing path strategies; and control the delivery flow rate of each port in the material mixing port, control the motion trajectory of the multi-axis linkage printing platform, and control the scanning path and exposure strategy of the scanning device in real time. For materials requiring mixing, the components are mixed in the central mixing chamber and then ejected from the nozzle. For sacrificial materials, they are ejected directly from the dedicated outlet of the nozzle.

[0014] The data acquisition and monitoring unit is used to monitor the printer's operating status to ensure the stability and accuracy of the printing process. The operating status includes printhead position, material flow rate, curing light intensity, and platform temperature.

[0015] The negative pressure extraction system includes a negative pressure source, a filtration pipeline network, a filter collection tank, and a vacuum control valve. The filtration pipeline network is pre-embedded within the macroscopic fracture and joint network during model printing. Microporous filter heads are installed at the ends of the filtration pipeline network. The outlet of the filtration pipeline network is connected to the inlet of the filter collection tank. The outlet of the filter collection tank is connected to the negative pressure source via the vacuum control valve. After the model is printed and cured, the negative pressure source is activated and the vacuum control valve is opened. Under negative pressure, the uncured liquid sacrificial material in the model is sequentially extracted and collected through the filtration pipeline network and the filter collection tank, thereby forming a clear macroscopic fracture and joint network in the cured rock mass model.

[0016] Furthermore, the base photosensitive resin is selected from epoxy acrylate resin. The toughening resin is selected from polyurethane acrylate. The reinforcing filler is selected from nano-silica powder. The reinforcing filler is used to enhance the stiffness and strength of the material. The adjusting filler is selected from nano-clay. The adjusting filler is used to adjust the toughness and thixotropy.

[0017] Furthermore, the photoinitiator is selected from one or more combinations of TPO, 184, or 819 / ITX.

[0018] Furthermore, the functional additives include TMPTA, HDDA, PETA, and CTFA. The P06 port is divided into multiple sub-compartments. Each sub-compartment delivers a single functional additive.

[0019] Furthermore, the sacrificial material is selected from base resin or silicone oil. The sacrificial material does not chemically fuse with the photosensitive resin.

[0020] The present invention also discloses a method for preparing a discontinuous rock slope model with complex structural surfaces according to the above-mentioned device, comprising the following steps:

[0021] Step 1. 3D Random Field Modeling and Data Preparation. Obtain borehole survey data for the target area and construct a 3D rock mass parameter field model using random field modeling units. Generate a random field representing the spatial variation of rock physical and mechanical parameters based on random field theory and embed it into the 3D heterogeneous rock mass model to characterize the spatial variability of the rock mass. Discretize the random field into a background mesh and convert it into material mix proportion codes for each element, then connect it to the main control computer.

[0022] Step 2. Layer-by-layer execution of model printing and synchronous curing. The main control computer converts the material mixing code into spatially discrete differentiated material mixing instructions and printing paths, and controls the material mixing port, multi-axis linkage printing platform and scanning equipment to work together in real time.

[0023] Step 3: The realization of complex geological structures during the layer-by-layer printing process in Step 2.

[0024] Step 4: Sacrificial Material Removal and Final Model Formation. After printing and curing all layers, a negative pressure removal step is performed. The outlet end of the pre-embedded filtration pipeline network inside the model is reliably connected to the filter collection tank. The vacuum control valve is opened and the negative pressure source is activated to create a stable negative pressure environment within the system. Under negative pressure, all uncured liquid sacrificial material in the model is forcibly extracted and collected in the filter collection tank. When the sacrificial material has been completely removed, an internally connected macroscopic fracture and joint network, perfectly consistent with the design, is formed in the cured rock mass model, ultimately resulting in a discontinuous rock slope model.

[0025] Furthermore, Step 2 proceeds with the following operations layer by layer:

[0026] Step 2.1. Material Delivery and Spraying. Based on the spatial location of the current printing layer and the required lithology, the main controller controls the corresponding ports to deliver materials according to the set ratio. For rock matrix, the required photosensitive resin, filler, and microspheres are mixed in the central mixing chamber of the intelligent adjustable nozzle and then sprayed onto the multi-axis linkage printing platform. For macroscopic fractures and joints, the photosensitive resin material port is closed, the Sac port is opened, and the sacrificial material is directly sprayed onto the preset fracture space path.

[0027] Step 2.2. Synchronous Selective Scanning and Curing. After the material spraying of a layer is completed, the scanning equipment is immediately activated, and selective exposure and curing are performed based on the cross-sectional information of the layer provided by the main control unit, after deducting the fracture area. The matrix area of ​​the rock mass is scanned and cured, while the fracture trajectory area occupied by the sacrificial material is not exposed, keeping it in a liquid state.

[0028] Furthermore, Step 3 achieves specific geological structures in the following ways:

[0029] Lithological interface gradient transition: When the nozzle crosses the boundary of different lithological units, the main control unit executes gradient switching commands for the material mix ratio, continuously adjusting the delivery ratio of each port within a millimeter range to gradually change the material properties and form a smooth transition zone. Microstructural characterization (e.g., SEM) and mechanical property testing (e.g., nanoindentation) are used to verify the continuity of the gradient transition zone and the smooth change in properties, enhancing the realism of the interface treatment.

[0030] Microporous structure construction: When it is necessary to simulate micropores, the main controller synchronously starts the P01 port and the SO1 port, so that the basic photosensitive resin and hollow glass microspheres in a predetermined ratio are mixed in the central mixing chamber and then sprayed out. After scanning and curing, the microspheres are solidified in the matrix to form micropores.

[0031] Complex structural space forming: For synclinal and anticline structures, the main control unit controls the rotation of the multi-axis linkage printing platform on the A and B axes, so that the nozzles deposit material along the imaginary inclined surface of the stratum. At the same time, the scanning equipment dynamically adjusts the focal plane to align with the inclined printing surface to ensure curing quality.

[0032] The technical effects of this invention are beyond doubt:

[0033] A. It achieves high-fidelity physical reproduction of the complex internal structure and spatial variability of rock masses. Geological exploration data is directly and accurately converted into a three-dimensional physical model, overcoming the limitations of traditional homogeneous models. By controlling the mix proportions and distribution of materials, the spatial variability of rock mass mechanical parameters can be quantitatively simulated, making the physical model more closely resemble real engineering rock masses in terms of heterogeneous characteristics. This provides an unprecedented physical sample for studying the mechanical behavior of heterogeneous rock masses.

[0034] B. It can produce non-penetrating or penetrating cracks that exist inside the model, have complex shapes, and have a positional accuracy of sub-millimeter level, which greatly improves the structural similarity between the model and the prototype.

[0035] C. By switching material ratios in real time, a transition zone with continuously changing mechanical properties can be formed between hard rock masses and weak interlayers. This allows stress to be transferred and redistributed more naturally among different lithological units when the model is under load, thus more realistically simulating the failure mechanism of rock masses;

[0036] D. By incorporating hollow glass microspheres with specific parameters, the initial microporosity and permeability of the model can be quantitatively controlled. This provides a key technical means for studying the deformation and failure of rock masses under seepage-stress coupling. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the device structure;

[0038] Figure 2 This is a schematic diagram of a discontinuous rock slope model.

[0039] Figure 3 This is a flowchart of the method.

[0040] Figure 4 A schematic diagram of a syncline / antialine construction (in this diagram, only the rear nozzles are used, and the diagram shows that the nozzles have rotational capabilities and can spray materials from different directions).

[0041] Figure 5 A schematic diagram of the construction of pores and microcracks (in this diagram, O represents pores, and the material needs to be mixed in the mixing chamber before spraying).

[0042] Figure 6 A schematic diagram of negative pressure extraction of sacrificial material (in this diagram, extraction pipe micro-holes are set on the side of the model chamber, and the pipes can be inserted at a specified position as required during extraction).

[0043] In the diagram: 21. Main control unit; 22. Material storage device; 23. Material proportioning port; 24. Multi-axis linkage printing platform; 25. Scanning device; 4. Negative pressure extraction unit. Detailed Implementation

[0044] The present invention will be further described below with reference to embodiments, but it should not be construed that the scope of the present invention is limited to the following embodiments. Various substitutions and modifications made based on ordinary technical knowledge and common practices in the art without departing from the above-described technical concept of the present invention should be included within the scope of protection of the present invention.

[0045] Example 1:

[0046] See Figures 1-6 This embodiment provides an apparatus for preparing a discontinuous rock slope model with complex structural surfaces, including a random field modeling unit, a rock mass 3D printing modeling system, a data acquisition and monitoring unit, and a negative pressure extraction unit 4.

[0047] The random field modeling unit is used to generate a three-dimensional heterogeneous rock mass model characterizing the spatial variability of rock mass parameters based on random field theory. The random field modeling unit includes a data processing module, a random field generation module, and a mesh discretization module. The data processing module receives and preprocesses borehole exploration data from geotechnical engineering. The random field generation module, based on random field theory, sets the coefficient of variation (COV) to 0.2 and the correlation distance (θ) to 0.5m, and uses the covariance matrix decomposition method to generate a three-dimensional rock mass parameter field model. The mesh discretization module discretizes the random field into a 1cm³ voxel grid and converts the parameters of each voxel into material mix proportion codes. The random field modeling unit is connected to the main control computer 21 via a data interface.

[0048] The rock mass 3D printing modeling system includes a main control unit 21, a material storage device 22, a material mixing port 23, a multi-axis linkage printing platform 24, and a scanning device 25. The main control unit 21 is connected to the material mixing port 23, the multi-axis linkage printing platform 24, and the scanning device 25. The material storage device 22 is connected to the intelligent adjustable nozzle through the material mixing port 23. The material mixing port 23 integrates multiple independently numbered supply compartments, including a P01 port for conveying basic photosensitive resin, a P02 port for conveying toughening resin, a P03 port for conveying reinforcing filler, a P04 port for conveying adjusting filler, a P05 port for conveying photoinitiator, a P06 port for conveying functional additives, an S01 port for conveying hollow glass microspheres, and a Sac port for conveying sacrificial material. The intelligent adjustable nozzle has a central mixing chamber and input channels corresponding to the above ports. The multi-axis linkage printing platform 24 can move in the X, Y, and Z directions and has rotation functions along the A and B axes, allowing the printhead to approach the printing surface at a non-perpendicular angle and deposit material along complex inclined surfaces. After material ejection, the scanning device 25 selectively scans and cures areas other than the sacrificial material trajectory according to the instructions of the main controller 21. The main controller 21 is configured to: receive a three-dimensional digital model from the random field modeling unit, resolve the three-dimensional digital model into spatially continuously changing material mixing ratio instructions and printing path strategies, and control the delivery flow rate of each port in the material mixing port 23 in real time, control the movement trajectory of the multi-axis linkage printing platform 24, and control the scanning path and exposure strategy of the scanning device 25. For materials that need to be mixed, the components are mixed in the central mixing chamber and then ejected by the printhead. For sacrificial materials, they are ejected directly from the dedicated outlet of the printhead.

[0049] The data acquisition and monitoring unit monitors the printer's operating status to ensure the stability and accuracy of the printing process. The operating status includes printhead position, material flow rate, curing light intensity, and platform temperature. The data acquisition and monitoring unit includes multiple sensors, a data acquisition unit, and monitoring software. The sensors include a photoelectric encoder (for monitoring printhead position), an electromagnetic flowmeter (for monitoring material flow rate), an ultraviolet light intensity sensor (for monitoring curing light intensity), and a thermocouple (for monitoring platform temperature). The data acquisition unit (such as an NI DAQ card) acquires sensor data in real time and transmits it to the main controller 21 via a bus (such as PCIe). The monitoring software (based on LabVIEW or a custom API) displays operating status curves (such as flow-time curves and light intensity-position curves) and triggers alarms or feedback control to adjust printing parameters when parameters exceed thresholds.

[0050] The negative pressure extraction system 4 includes a negative pressure source, a filtration pipeline network, a filter collection tank, and a vacuum control valve. The filtration pipeline network is pre-embedded within the macroscopic fracture and joint network during model printing. Microporous filter heads are installed at the ends of the filtration pipeline network. The outlet of the filtration pipeline network is connected to the inlet of the filter collection tank. The outlet of the filter collection tank is connected to the negative pressure source via the vacuum control valve. After the model is printed and cured, the negative pressure source is activated and the vacuum control valve is opened. Under negative pressure, the uncured liquid sacrificial material in the model is sequentially extracted and collected through the filtration pipeline network and the filter collection tank, thus forming a clear macroscopic fracture and joint network in the cured rock mass model. The negative pressure extraction system 4 is readily available on the market and can be used directly; it is not particularly specialized.

[0051] Example 2:

[0052] This embodiment is similar in main content to Embodiment 1, except that the base photosensitive resin is epoxy acrylate resin. The toughening resin is polyurethane acrylate. The reinforcing filler is nano-silica powder. The reinforcing filler is used to enhance the stiffness and strength of the material. Experimental verification shows that for every 1% increase in the nano-silica powder content, the uniaxial compressive strength of the printed specimen can be increased by 3%, and the elastic modulus by 2%, demonstrating the precise controllability of the formulation. The adjusting filler is nano-clay. The adjusting filler is used to adjust toughness and thixotropy. The photoinitiator is one or a combination of TPO, 184, or 819 / ITX. The functional additives include TMPTA, HDDA, PETA, and CTFA. The P06 port is divided into multiple sub-compartments. Each sub-compartment delivers a single functional additive. The sacrificial material is either the base resin or silicone oil. The sacrificial material does not chemically fuse with the photosensitive resin.

[0053] Example 3:

[0054] This embodiment provides a method for preparing a discontinuous rock slope model with complex structural surfaces according to the apparatus described in Embodiment 1 or 2, comprising the following steps:

[0055] Step 1. 3D Random Field Modeling and Data Preparation. Obtain borehole survey data for the target area and construct a 3D rock mass parameter field model using random field modeling units. Generate a random field representing the spatial variation of rock physical and mechanical parameters based on random field theory and embed it into the 3D heterogeneous rock mass model to characterize the spatial variability of the rock mass. Discretize the random field into a background mesh and convert it into material mix proportion codes for each element, then connect it to the main control computer 21.

[0056] a) Establishing the trend function: Based on the spatial distribution patterns of rock mass parameters analyzed from the exploration data, a trend function μ(μ) is established. For relatively stable areas, a constant trend function is used.

[0057]

[0058] For parameters with a clear spatial trend (such as intensity varying with depth), a linear trend function is used:

[0059]

[0060] In the formula, μ(X) is the trend value of the parameter at spatial location X = (x, y, z). μ0 is the constant average value of the regional parameter. a and b are the regression coefficients obtained by fitting the borehole data using the least squares method.

[0061] b) Definition of covariance structure:

[0062] The spatial correlation of parameters is described using an exponential covariance function:

[0063]

[0064] In the formula, C(h) is the covariance between two points separated by a vector h. σ² is the variance, characterizing the fluctuation range of the parameter. ‖h‖ is the Euclidean distance between the two points. θ is the correlation distance, set to 0.5 m.

[0065] c) Definition of coefficient of variation:

[0066]

[0067] In the formula, COV is the coefficient of variation, characterizing the relative variability of the parameter. σ is the standard deviation, which is the square root of the variance σ². μ is the population mean of the regional parameter.

[0068] d) Random field generation (covariance matrix decomposition method):

[0069] Step d.1: Discretize the model into a 1 cm³ voxel grid and construct an N×N covariance matrix Σ, where the elements are...

[0070] Σᵢⱼ = C(‖𝐱ᵢ - 𝐱ⱼ‖)

[0071] Step d.2: Perform Cholesky decomposition on the covariance matrix:

[0072]

[0073] In the formula, L is a lower triangular matrix.

[0074] Step d.3: Generate a standard normal random vector ξ ~ N(0, I).

[0075] Step d.4: Generate a random fluctuation field with a specified covariance structure:

[0076]

[0077] Step d.5: Synthesize the final random field:

[0078]

[0079] In the formula, Z is the final random field vector of rock mass parameters. μ is the trend field vector. ε is the random fluctuation field vector.

[0080] Step 2. Layer-by-layer execution of model printing and synchronous curing. The main control unit 21 converts the material mixing ratio code into spatially discrete differentiated material mixing ratio instructions and printing paths, and controls the material mixing port 23, multi-axis linkage printing platform 24, and scanning device 25 to work together in real time. Step 2 performs the following operations layer by layer:

[0081] Step 2.1. Material Delivery and Spraying. Based on the spatial location of the current printing layer and the required lithology, the main controller 21 controls the corresponding ports to deliver materials according to the set ratio. For the rock matrix, the required photosensitive resin, filler, and microspheres are mixed in the central mixing chamber of the intelligent adjustable nozzle and then sprayed onto the multi-axis linkage printing platform 24. For macroscopic fractures and joints, the photosensitive resin material port is closed, the Sac port is opened, and the sacrificial material is directly sprayed onto the preset fracture space path.

[0082] Step 2.2. Synchronous Selective Scanning and Curing. After the material spraying of a layer is completed, the scanning device 25 is immediately activated, and selective exposure and curing are performed based on the cross-sectional information of the layer provided by the main control unit 21, after deducting the fracture area. The matrix area of ​​the rock mass is scanned and cured, while the fracture trajectory area occupied by the sacrificial material is not exposed, keeping it in a liquid state.

[0083] Step 3: The implementation of complex geological structures during the layer-by-layer printing process in Step 2. Step 3 achieves specific geological structures through the following methods:

[0084] Lithological interface gradient transition: When the nozzle crosses the boundary of different lithological units, the main control unit 21 executes the gradient switching command of the material mix ratio, continuously adjusting the delivery ratio of each port within a millimeter range, so that the material properties change gradually and form a smooth transition zone. Through scanning electron microscopy (SEM) observation and indentation test verification, the gradient transition zone shows a continuous change in material structure with no visible interface, and the mechanical properties (such as hardness and compressive strength) transition smoothly, for example, a linear decrease from hard rock mass (150HV) to weak interlayer (80HV).

[0085] Microporous structure construction: When it is necessary to simulate micropores, the main controller 21 synchronously starts the P01 port and the SO1 port, so that the basic photosensitive resin and hollow glass microspheres in a predetermined ratio are mixed in the central mixing chamber and then sprayed out. After scanning and curing, the microspheres are solidified in the matrix to form micropores.

[0086] Complex structural space forming: For synclinal and anticline structures, the main controller 21 controls the rotation of the multi-axis linkage printing platform 24 on the A and B axes, so that the nozzles deposit material along the imaginary inclined surface of the stratum. At the same time, the scanning device 25 dynamically adjusts the focal plane to align with the inclined printing surface to ensure curing quality.

[0087] Step 4: Sacrificial Material Removal and Final Model Formation. After printing and curing all layers, a negative pressure removal step is performed. The outlet end of the pre-embedded filtration pipeline network inside the model is reliably connected to the filter collection tank. The vacuum control valve is opened and the negative pressure source is activated to create a stable negative pressure environment within the system. Under negative pressure, all uncured liquid sacrificial material in the model is forcibly extracted and collected in the filter collection tank. When the sacrificial material has been completely removed, an internally connected macroscopic fracture and joint network, perfectly consistent with the design, is formed in the cured rock mass model, ultimately resulting in a discontinuous rock slope model.

[0088] Example 4:

[0089] The main content of this embodiment is the same as that of Embodiment 3. However, for complete rock mass units without special structures, the main control unit 21 calls the corresponding standard formula (e.g., P01 (82%), P03 (7%), P05 (TPO, 5%), P06 (TMPTA, 6%)) according to the unit's design mechanical parameters. Materials are delivered to the central mixing chamber from each port in proportion. Nozzles cover the unit area according to a preset path. Subsequently, the scanning device 25 performs a comprehensive scan and curing of the entire area. The scanning path is a high-efficiency raster path or vector contour filling path to ensure complete material curing, forming a uniform, high-strength complete rock mass simulation material.

[0090] Example 5:

[0091] This embodiment is largely the same as embodiment 3. However, for the construction of the weak interlayer, when the nozzle enters the weak interlayer region, the main control unit 21 executes a gradient switching command for the material proportions. Ports P02 (PUA, 68%), P01 (epoxy resin, 15%), P05 (184 photoinitiator, 3%), and P06 (CTFA additive, 14%) deliver materials to the central mixing chamber according to the set proportions. When the nozzle crosses the upper and lower boundaries of the interlayer (within a transition range of approximately 1-2 mm), the main control unit 21 controls the metering pumps at each port to linearly reduce the original rock mass formula flow rate to 0%, while simultaneously linearly increasing the weak interlayer formula flow rate from 0% to 100%. In the interlayer and its transition zone, the scanning device 25 employs a full-area uniform exposure strategy. Since the material properties in this area need to change uniformly, the scanning path is a standard zigzag or raster-style filling to ensure that the entire interlayer and gradient transition zone receive uniform curing energy, thereby obtaining an interface with smoothly changing mechanical properties and ensuring interlayer bonding strength.

[0092] Example 6:

[0093] The main content of this embodiment is the same as that of embodiment 3, wherein:

[0094] A. Precise printing of macroscopic fracture and joint networks:

[0095] Angle and trajectory determination: The geometric parameters such as the dip angle, strike, and width of macroscopic fractures and joints are directly defined by the three-dimensional geological digital model. The main control unit 21 decomposes the three-dimensional spatial trajectory into a series of continuous two-dimensional movement paths located in different printing layers, and calculates the spatial coordinates (X, Y, Z) and movement vector of the nozzle at each path point.

[0096] Printing execution: When the printhead needs to construct macroscopic fractures, the main controller 21 instructs the Sac port to open and closes all photosensitive resin material ports (P01-P06, S01). The intelligent adjustable nozzle moves strictly along the preset fracture space path, directly spraying the sacrificial material onto the path. During the subsequent curing process, the scanning device (25) will skip the fracture trajectory area and not expose it, so that the sacrificial material remains liquid inside the cured rock matrix, forming a preset cavity channel.

[0097] Scanning and curing execution: After the material spraying of a complete layer is completed, the scanning device 25 is activated. Following the scanning path preset by the main control unit 21, it selectively exposes and cures all rock matrix areas except for the fracture trajectories occupied by the sacrificial material. The accuracy of the scanning path is ensured by the following: the scanning device's DLP surface projection system receives a vector path file from the main control unit, which has pre-excluded fracture areas. Simultaneously, the system employs closed-loop feedback control, using a laser positioning sensor to correct the positional error of the scanning spot in real time, ensuring that the cured area is completely consistent with the design model at the sub-millimeter level. This allows the sacrificial material to be completely encapsulated within the cured rock matrix, forming the preset cavity channels.

[0098] B. Refined construction of microporous structures:

[0099] The construction of microporous structures is a key innovative step in simulating the heterogeneity and permeability of rock masses. The printing process is as follows:

[0100] Command triggering and material delivery: The main controller 21 sends a collaborative work command to the material proportioning port (23).

[0101] Basic material delivery: The precision metering pump at port P01 (basic epoxy acrylate resin chamber) is started to deliver the basic photosensitive resin.

[0102] Porous material delivery: Simultaneously, the precision feeding device of port S01 (dedicated hollow glass microsphere supply chamber) is activated to stably output hollow glass microspheres at a predetermined mass flow rate (corresponding to a preset volume percentage, such as 10%).

[0103] Online mixing and slurry preparation: The base photosensitive resin delivered from port P01 and the hollow glass microspheres delivered from port S01 are synchronously transported to the central forced mechanical mixing chamber of the intelligent adjustable nozzle through their respective independent pipelines. This mixing chamber is equipped with a micro-dynamic stirrer (such as a spiral blade or static mixer) to ensure online, continuous, and uniform physical mixing of the two materials within a very short residence time, forming a suspended slurry and effectively preventing microsphere sedimentation and aggregation.

[0104] Slurry spraying and area control: The uniformly mixed slurry is then sprayed from the nozzle to the corresponding designated area on the multi-axis linkage printing platform 25. The nozzle's movement path, spray velocity (controlled by a metering pump), and start / stop are all controlled in real time at the millisecond level by the main control computer 21 based on the pore space distribution model of the layer, ensuring that the spatial distribution of the microporous structure is highly consistent with the geological model.

[0105] Simultaneous scanning and selective curing:

[0106] After the slurry is sprayed to the predetermined position, the scanning device 25—typically a high-precision ultraviolet laser or a digital light processor (DLP) system—immediately performs selective surface exposure or contour scanning on all sprayed material areas except for preset macroscopic cracks and joints (i.e., the trajectory of the sprayed sacrificial material) according to the instructions of the main controller 21.

[0107] The exposure energy and scanning path are precisely calculated to ensure that the photosensitive resin matrix undergoes a cross-linking reaction and cures rapidly, while the hollow glass microspheres encapsulated within it are firmly embedded in the cured resin matrix. Due to the chemical inertness and hollowness of the microspheres themselves, a large number of uniformly distributed, closed or interconnected micropores and microcracks with controllable size and density are formed inside the material, quantitatively simulating the original pore structure of the rock mass.

[0108] Relationship between porosity and microsphere volume fraction:

[0109]

[0110] In the formula, This represents the porosity of the model. This indicates the volume of the hollow glass microspheres. This indicates the total volume of the mixed slurry.

[0111] Density calculation after microsphere incorporation:

[0112]

[0113] In the formula, This indicates the density of the composite material. This indicates the density of the photosensitive resin (approximately 1.1-1.2 g / cm³). This indicates the density of the hollow glass microspheres (0.1-0.3 g / cm³).

[0114] C. Construction and angle realization of complex structures such as synclines and anticlines:

[0115] Angle Determination: The attitude (including dip angle and dip direction) of strata such as the axial plane and limbs of synclines and anticlines is precisely defined in a three-dimensional geological model. During slicing, the main control unit 21 not only divides the model into horizontal slices but also dynamically adjusts the material ratio instructions for different regions within each slice according to the structural morphology to simulate the tilt and curvature of the strata. Angle realization relies on a multi-axis linkage printing platform 24, which allows the print head to move in the X, Y, and Z directions while rotating along the A and B axes. This enables the print head to approach the printing surface at a non-perpendicular angle, depositing material along the imaginary surface of the tilted strata, thus achieving high-precision spatial angle reproduction. Angle Implementation Mechanism: The spatial morphology of complex structures is realized through the coordinated movement of the multi-axis linkage printing platform 24. This platform not only provides linear motion along the X, Y, and Z axes but also integrates the A-axis (rotation around the X-axis) and the B-axis (rotation around the Y-axis). The main controller 21 calculates and controls the rotation angle of the printing platform on the A and B axes in real time based on the normal vector of the structural surface, so that the current printing plane always maintains the best fit with the local stratum dip and inclination, thereby realizing the nozzle to perform tangential printing along the complex inclined surface and accurately deposit materials.

[0116] Print execution:

[0117] Taking the fracture zone in the core of an anticline as an example: the main controller 21 instructs the nozzle to move to the core area of ​​the anticline. At this time, the nozzle mainly delivers materials from the ports of P01 (base resin), P04 (nano clay), P05 (photoinitiator TPO) and P06 (PETA additive) in a ratio of 75%:4%:4%:17%. These materials are mixed in the central mixing chamber of the nozzle and then sprayed out to simulate the lithology of the fracture zone.

[0118] Simultaneously, to simulate the high porosity and fractures of the core, the main controller 21 will synchronously activate port S01, mixing hollow glass microspheres with the aforementioned slurry at a volume ratio of 15% in the central mixing chamber before spraying them out together. Then, at a predetermined position, it will switch to port Sac to spray sacrificial material to construct tensile fractures.

[0119] Taking the transition zone of the syncline fin as an example: as the nozzle moves from the anticline core to the syncline fin, the main control unit 21 controls the material ratio to gradually change from the "fracture zone formula" to the "transition zone formula". The transition zone formula is composed of P01 (80%), P03 (6%), P05 (184 photoinitiator, 5%), and P06 (CTFA additive, 9%) mixed in the central mixing chamber. During this process, the multi-axis platform controls the nozzle to move along the stratigraphic interface (with a certain dip angle) to ensure that the material is spatially deposited according to the geological occurrence.

[0120] Scanning and curing execution: For such complex structures, the exposure strategy of the scanning device 25 is synchronized and coordinated with the material printing. It performs scanning and curing based on the cross-sectional information of the layer, after deducting the crack area, provided in real time by the main controller 21. Through a dynamic focusing system and contour filling algorithm, it ensures that the focal plane of the ultraviolet laser or DLP projection remains consistent with the material deposition surface on inclined or even curved printing surfaces, resulting in uniform energy distribution and thus achieving high-quality, high-precision curing under complex geometries.

[0121] Example 7:

[0122] This embodiment is largely the same as embodiment 3. In Step 1, 100 sets of geotechnical engineering investigation data were collected from the target area, including: rock mass quality index RQD: 40%–90%, joint roughness coefficient JRC: 6–18, uniaxial compressive strength: 30–150 MPa, internal friction angle φ: 28°–38°, and rock mass density: 1.8–2.5 g / cm³. Using a random field modeling unit, with a coefficient of variation COV = 0.2 and a correlation distance of 0.5 m, a three-dimensional rock mass parameter field model was generated using the covariance matrix decomposition method. The model was discretized into a 1 cm³ voxel grid, with each voxel containing coordinates (x, y, z), internal friction angle, and gradation curve parameters (d). 10 =0.55–0.75 mm, Cu = 1.5–4.0) and relative density Dr = 0.55–0.75.

[0123] Example 8:

[0124] The main content of this embodiment is the same as that of embodiment 3. In step 2, the voxel data is converted into material ratio code and transmitted to the main control computer of the 3D printing system.

[0125] The material proportions are set according to the lithological region as follows:

[0126]

[0127] 1. Regarding the control of material stiffness and strength:

[0128] Experiments have verified a strong positive correlation between the content of reinforcing filler (nano-silica powder) and the material's stiffness and strength. When the volume content of nano-silica powder (PO3 port) in the base resin increased from 0% to 10%, the uniaxial compressive strength (UCS) of the printed specimen showed an almost linear increase, rising from 15 MPa to 45 MPa. This means that for every 1% increase in content, the uniaxial compressive strength increased by an average of approximately 3 MPa. Simultaneously, the elastic modulus also increased from 0.8 GPa to 2.5 GPa, demonstrating that the "hardness" of the model rock mass can be quantitatively controlled by adjusting the flow rate at the PO3 port.

[0129] 2. Regarding the control of material toughness and deformation capacity:

[0130] The introduction of toughening resin (polyurethane acrylate) effectively improves the brittleness of the material. When the mass percentage of toughening resin (PO2 port) in the mixed resin matrix increases from 0% to 30%, the peak strain (deformation capacity at failure) of the printed specimen significantly increases from 1.5% to 4.0%. However, its uniaxial compressive strength decreases nonlinearly from 40 MPa to 25 MPa. This trade-off provides a precise formulation design window for simulating the mechanical behavior of rock formations ranging from hard and brittle to soft and ductile.

[0131] 3. Simulation of internal cohesion and internal friction angle within the rock mass:

[0132] By synergistically adjusting the ratio of reinforcing filler to regulating filler, independent control of rock mass shear strength parameters (cohesion c and internal friction angle φ) can be achieved. Experimental data show that increasing the content of nano-clay (PO4 port) significantly improves the material's cohesion (mainly affecting the "integrity" of the rock mass), while having a smaller impact on the internal friction angle. Specifically, when the PO4 port content increases from 2% to 8%, the cohesion c increases linearly from 1.2 MPa to 2.8 MPa, while the internal friction angle φ only slightly increases from 35° to 38°. This lays the foundation for accurately reproducing the Mohr-Coulomb strength criterion for specific rock masses.

[0133] 4. Quantitative construction of microporosity and permeability:

[0134] The introduction of microporous structures is crucial for simulating the seepage characteristics of rock masses. By controlling the volume ratio of hollow glass microspheres (S01 ports), the initial porosity of the model can be quantitatively controlled. When the microsphere content increases from 0% to 20%, the measured porosity of the model linearly increases from <0.5% to 18.5%, while its gas permeability increases by two orders of magnitude. This relationship makes it possible to prepare fractured-porous rock mass models with specific seepage characteristics.

[0135] 5. Precise control of the brittle-ductile transition in materials:

[0136] The addition of functional additives (such as TMPTA) can effectively regulate the crosslinking density of materials, thereby controlling their brittle-ductile properties. When the mass fraction of TMPTA (one of the sub-compartments of the P06 port) in the formulation increased from 5% to 20%, the fracture energy (characterizing the material's resistance to crack propagation) of the printed specimen increased from 50 J / m² to 150 J / m², indicating that the material is transitioning from brittle fracture to quasi-brittle / ductile fracture. This provides a material basis for simulating rock mass failure behavior under different confining pressures.

[0137] 6. Verification of the continuity of mechanical properties in the gradient transition region:

[0138] Nanoindentation tests on the gradient transition zone showed a seamless transition in mechanical properties. In a 5mm long region transitioning from hard rock (Formula A) to a weak interlayer (Formula B), the microhardness test value smoothly and almost linearly decreased from 150 HV to 80 HV without any abrupt changes in performance. This directly demonstrates the unique advantages of the method of this invention in simulating complex lithological contact zones.

[0139] Example 9:

[0140] This embodiment is similar to Embodiment 3 in its main content. However, from the final printed heterogeneous rock mass model, samples are taken from different lithological regions (such as intact rock mass, weak interlayers, and fractured zones) using a micro-drilling rig and processed into standard cylindrical specimens. These printed rock-like specimens are subjected to uniaxial or triaxial compression tests to obtain their uniaxial compressive strength, elastic modulus, cohesion, internal friction angle, and other mechanical parameters. The test results are compared and analyzed with laboratory test data from corresponding rock cores from the original engineering exploration boreholes. When the deviation of the key mechanical parameters of the printed specimen from the natural rock core test data is controlled within ±15%, the 3D printed model is considered to effectively reproduce the mechanical properties of the real rock mass.

[0141] Repeat the above steps, record the spatial variability model of different physical and mechanical parameters, and compare the obtained experimental results with numerical simulations.

Claims

1. An apparatus for preparing a model of a discontinuous rock slope containing complex structural planes, characterized in that: It includes a random field modeling unit, a rock mass 3D printing modeling system, a data acquisition and monitoring unit, and a negative pressure extraction unit (4). The random field modeling unit is used to generate a three-dimensional heterogeneous rock mass model that characterizes the spatial variability of rock mass parameters based on random field theory. The rock mass 3D printing modeling system includes a main control unit (21), a material storage device (22), a material mixing port (23), a multi-axis linkage printing platform (24), and a scanning device (25). The main control unit (21) is connected to the material mixing port (23), the multi-axis linkage printing platform (24), and the scanning device (25) respectively. The material storage device (22) is connected to the intelligent adjustable nozzle through the material mixing port (23). The material mixing port (23) integrates multiple independently numbered supply compartments, including a P01 port for conveying basic photosensitive resin, a P02 port for conveying toughening resin, a P03 port for conveying reinforcing filler, a P04 port for conveying adjusting filler, a P05 port for conveying photoinitiator, a P06 port for conveying functional additives, an S01 port for conveying hollow glass microspheres, and a port for conveying sacrificial material. The Sac port; the intelligent adjustable printhead has a central mixing chamber and an input channel corresponding to the above port; the multi-axis linkage printing platform (24) can move in the X, Y, and Z directions and has rotation functions on the A and B axes, so that the printhead can approach the printing surface at a non-perpendicular angle and accumulate material along the complex inclined surface; after the material is sprayed, the scanning device (25) selectively scans and cures the area except for the sacrificial material trajectory according to the instructions of the main controller (21); the main controller (21) is configured to: receive the three-dimensional digital model from the random field modeling unit, parse the three-dimensional digital model into a material mix ratio instruction and printing path strategy that change continuously in space, and control the delivery flow of each port in the material mix ratio port (23), control the motion trajectory of the multi-axis linkage printing platform (24), and control the scanning path and exposure strategy of the scanning device (25) in real time; For materials that need to be mixed, the components are mixed in the central mixing chamber and then sprayed from the nozzle; for sacrificial materials, they are sprayed directly from the dedicated outlet of the nozzle. The data acquisition and monitoring unit is used to monitor the printer's operating status to ensure the stability and accuracy of the printing process; the operating status includes printhead position, material flow rate, curing light intensity, and platform temperature; After the model is printed and cured, the negative pressure extraction unit (4) is activated. Under the action of negative pressure, the uncured liquid sacrificial material in the model is extracted and separated and collected, thereby forming a clear macroscopic fracture and joint network in the cured rock mass model.

2. The apparatus for preparing a discontinuous rock slope model with complex structural surfaces according to claim 1, characterized in that: The random field modeling unit includes a data processing module, a random field generation module, and a grid discretization module; the data processing module is used to receive and preprocess geotechnical engineering borehole exploration data; the random field generation module generates a spatial random field of rock mass parameters based on random field theory, setting the coefficient of variation and correlation distance; the grid discretization module discretizes the random field into a background grid and converts the parameters of each grid unit into material mix proportion codes; the random field modeling unit is connected to the main control computer (21) through a data interface to transmit the three-dimensional digital model and material mix proportion codes; The data acquisition and monitoring unit includes a data acquisition unit, monitoring software, and multiple sensors; the sensors include a photoelectric encoder, an electromagnetic flowmeter, an ultraviolet light intensity sensor, and a thermocouple; the data acquisition unit collects sensor data in real time and transmits it to the main control unit (21); the monitoring software displays the operating status and triggers an alarm or adjusts the printing parameters when the parameters are abnormal; The negative pressure extraction system (4) includes a negative pressure source, a filtration pipeline network, a filter collection tank, and a vacuum control valve. The filtration pipeline network is pre-embedded in the macroscopic fracture and joint network during the model printing process. The end of the filtration pipeline network is equipped with a microporous filter head. The outlet end of the filtration pipeline network is connected to the inlet of the filter collection tank. The outlet of the filter collection tank is connected to the negative pressure source through the vacuum control valve. After the model is printed and cured, the negative pressure source is started and the vacuum control valve is opened. Under the action of negative pressure, the uncured liquid sacrificial material in the model is extracted and separated and collected in sequence through the filtration pipeline network and the filter collection tank, thereby forming a clear macroscopic fracture and joint network in the cured rock mass model.

3. The apparatus for preparing a discontinuous rock slope model with complex structural surfaces according to claim 1, characterized in that: The base photosensitive resin is selected from epoxy acrylate resin; the toughening resin is selected from polyurethane acrylate; the reinforcing filler is selected from nano-silica powder; the reinforcing filler is used to enhance the stiffness and strength of the material; the regulating filler is selected from nano-clay; the regulating filler is used to adjust toughness and thixotropy.

4. The apparatus for preparing a discontinuous rock slope model with complex structural surfaces according to claim 1, characterized in that: The photoinitiator is selected from one or more combinations of TPO, 184, or 819 / ITX.

5. The apparatus for preparing a discontinuous rock slope model with complex structural surfaces according to claim 1, characterized in that: The functional additives include TMPTA, HDDA, PETA, and CTFA; the P06 port is divided into multiple sub-compartments; each sub-compartment delivers a single functional additive.

6. The apparatus for preparing a discontinuous rock slope model with complex structural surfaces according to claim 1, characterized in that: The sacrificial material is selected from base resin or silicone oil; the sacrificial material does not chemically fuse with the photosensitive resin.

7. A method for preparing a discontinuous rock slope model with complex structural surfaces using the apparatus according to any one of claims 1 to 6, characterized in that, Includes the following steps: Step 1. Three-dimensional random field modeling and data preparation; Obtain the geotechnical engineering borehole survey data of the target area, and construct a three-dimensional rock mass parameter field model using random field modeling units; Generate a random field based on the random field theory to represent the spatial variation of rock physical and mechanical parameters, and embed it into the three-dimensional heterogeneous rock mass model to characterize the spatial variability of the rock mass; Discretize the random field into a background grid, and convert it into the material mix ratio code of each unit, and connect it to the main control computer (21); Step 2. Layer-by-layer execution of model printing and synchronous curing; the main control unit (21) converts the material mix ratio code into spatially discrete differentiated material mix ratio instructions and printing paths, and controls the material mix ratio port (23), multi-axis linkage printing platform (24) and scanning device (25) to work together in real time; Step 3: The realization of complex geological structures during the layer-by-layer printing process in Step 2; Step 4: Sacrificial Material Removal and Final Model Formation; After printing and curing all layers, perform the negative pressure removal step; Reliably connect the outlet end of the pre-embedded filtration pipeline network inside the model to the filter collection tank; Open the vacuum control valve and start the negative pressure source to create a stable negative pressure environment in the system; Under the action of negative pressure, all uncured liquid sacrificial materials in the model are forcibly extracted and separated and collected by the filter collection tank; When the sacrificial materials are completely removed, an internally connected macroscopic fracture and joint network that is completely consistent with the design is formed in the cured rock mass model, finally obtaining the discontinuous rock slope model.

8. The method for preparing a discontinuous rock slope model with complex structural planes according to claim 7, characterized in that: In Step 1, the covariance matrix decomposition method is used to generate random fields.

9. The method for preparing a discontinuous rock slope model with complex structural planes according to claim 7, characterized in that, Step 2: Perform the following operations layer by layer: Step 2.

1. Material delivery and spraying; According to the spatial position of the current printing layer and the rock type to be simulated, the main controller (21) controls the corresponding port to deliver the material according to the set ratio; For the rock matrix, the required photosensitive resin, filler and microspheres are mixed in the central mixing chamber of the intelligent adjustable nozzle and then sprayed to the multi-axis linkage printing platform (24); For macroscopic cracks and joints, the photosensitive resin material port is closed and the Sac port is opened, and the sacrificial material is directly sprayed onto the preset crack space path; Step 2.

2. Synchronous selective scanning and curing; After the material spraying of a layer is completed, the scanning device (25) is immediately started and selectively exposed and cured according to the cross-sectional information of the layer with the crack area deducted provided by the main controller (21); the rock matrix area is scanned and cured, while the crack trajectory area occupied by the sacrificial material is not exposed and is kept in liquid state.

10. The method for preparing a discontinuous rock slope model with complex structural planes according to claim 7, characterized in that, Step 3 achieves specific geological structures through the following methods: Lithological interface gradient transition: When the nozzle crosses the boundary of different lithological units, the main control unit (21) executes the gradient switching command of the material mix ratio, continuously adjusts the delivery ratio of each port within the millimeter range, so that the material properties change gradually and form a smooth transition zone; Microporous structure construction: When it is necessary to simulate micropores, the main controller (21) synchronously starts the P01 port and the SO1 port, so that the basic photosensitive resin and the hollow glass microspheres in a predetermined ratio are mixed in the central mixing chamber and sprayed out. After scanning and curing, the microspheres are solidified in the matrix to form micropores. Complex structural space forming: For synclinal and anticlinal structures, the main controller (21) controls the rotation of the multi-axis linkage printing platform (24) on the A and B axes, so that the nozzles accumulate material along the imaginary inclined surface of the stratum. At the same time, the scanning device (25) dynamically adjusts the focal plane to align with the inclined printing surface to ensure curing quality.

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