Micro-nano robot grouting method and system in rock true triaxial shear test

Abstract

The invention discloses a micro-nano robot grouting method and system in a rock true triaxial shear test, and the method comprises the steps: carrying out complex stress path loading on a rock sample in a true triaxial stress environment, and generating a three-dimensional fracture network; according to the three-dimensional fracture network, a micro-nano robot is driven to conduct global scanning on the fracture topological structure, and a fracture three-dimensional model is obtained; according to the crack three-dimensional model, the optimal grouting path of the micro-nano robot is planned; according to the optimal grouting path, the micro-nano robot is controlled to carry slurry to carry out directional grouting on the crack, and a sample obtained after grouting is obtained; scanning the grouted sample through intermittent low-dose micron nano-CT (Computed Tomography) to obtain grouting filling data; and according to the grouting filling data, after the optimal grouting path or grouting parameters are corrected in a closed loop mode, grouting is completed. According to the device and the method, accurate filling of micron-sized cracks is realized, and the test efficiency and the grouting success rate are remarkably improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of geotechnical engineering reinforcement, and particularly relates to a micro-nano robot grouting method and system in rock true triaxial shear test. BACKGROUND

[0002] Existing rock grouting reinforcement tests are mostly carried out under uniaxial or conventional triaxial conditions, and it is difficult to truly reflect the crack evolution and grouting response behavior of deep rock mass under complex stress state. In contrast, the true triaxial test can independently control the three principal stresses, and can more accurately simulate the three-dimensional stress path and crack propagation process of underground rock mass under excavation, disturbance or tectonic action, providing a more reliable physical platform for studying the fracture mechanism and reinforcement effect of heterogeneous rock.

[0003] However, the traditional grouting test usually needs to carry out grouting operation under the condition of pressure relief or mold opening, which leads to stress relaxation, closure or expansion distortion of the crack structure, and it is difficult to evaluate the penetration and filling behavior of the grout under the true stress state. In addition, the existing methods mostly rely on manual intervention, and there are problems such as low crack identification accuracy, uncontrollable grouting path, poor filling uniformity, and lack of effective means for precise grouting of micron-level cracks.

[0004] Therefore, it is urgent to develop a test method that can realize three-dimensional identification of cracks, intelligent planning of grouting path and precise grouting at micro-nano level under the premise of keeping true triaxial stress state throughout the test, so as to improve the controllability and reliability of grouting reinforcement of complex crack rock mass. SUMMARY

[0005] To solve the above technical problems, the application provides a micro-nano robot grouting method and system in rock true triaxial shear test. One micro-nano robot grouting method in rock true triaxial shear test comprises: loading complex stress path on the rock sample under true triaxial stress environment to generate a three-dimensional crack network; driving the micro-nano robot to globally scan the crack topological structure according to the three-dimensional crack network to obtain a three-dimensional crack model; planning an optimal grouting path of the micro-nano robot according to the three-dimensional crack model; controlling the micro-nano robot to carry out directional grouting on the crack according to the optimal grouting path, and obtaining a grouted sample; intermittently scanning the grouted sample by low-dose micron-level nano-CT to obtain grouting filling data; completing grouting after loop correcting the optimal grouting path or grouting parameters according to the grouting filling data.

[0006] Preferably, in the process of loading the rock sample under complex stress path in the true triaxial stress environment, the process of generating the three-dimensional fracture network comprises: According to the stage stress ratio : =2:1:1, the rock sample is loaded to a preset pressure value; According to the keeping unchanged, the loading mode is continuously increased and , the initial fracture propagation is obtained; According to the application of sinusoidal cyclic loading to and , the final three-dimensional fracture network is obtained.

[0007] Preferably, according to the three-dimensional fracture network, the process of driving the micro-nano robot to globally scan the fracture topology to obtain a three-dimensional fracture model comprises: According to the micro-probe carried by the micro-nano robot, the infrared structured light is projected to obtain a depth map; According to the depth map and the intrinsic matrix of the micro-probe, the pixel coordinates are converted into 3D point cloud; Fusion of all 3D point cloud data, obtain the three-dimensional fracture model.

[0008] Preferably, according to the three-dimensional fracture model, the process of planning the optimal grouting path of the micro-nano robot comprises: According to the maximum fracture coverage and the minimum robot energy consumption, a multi-objective function is established; According to the real-time stress data of the true triaxial, the high-pressure closed area is identified; By avoiding the constraint of the high-pressure closed area, the multi-objective function is solved to obtain the optimal grouting path.

[0009] Preferably, according to the optimal grouting path, the process of controlling the micro-nano robot to carry out directional grouting on the fracture with slurry material comprises: According to the Pt catalytic end of the Janus type micro motor carried by the micro-nano robot, H2O2 is decomposed to generate O2 bubbles to obtain propulsion; According to the H2O2 concentration gradient established by the micro-fluidic chip, the robot speed is controlled to be 10-50 μm / s; According to the release of nano cement slurry by the porous SiO2 slurry carrying end, the directional grouting on the fracture is carried out.

[0010] Preferably, the process of obtaining grouting filling data by intermittently scanning the grouted sample with low-dose micron-level nano-CT comprises: Before scanning, the robot motion is paused, and according to the dual-energy spectrum micron-level nano-CT decomposition, the micro-nano robot and the fracture are distinguished; According to the deep learning de-artifact algorithm, high-confidence grouting filling data is obtained.

[0011] Preferably, after the optimal grouting path or grouting parameter is closed-loop corrected according to the grouting filling data, the process of completing grouting comprises: According to the PID controller, the filling rate deviation is calculated to obtain a correction amount. According to the correction amount, the motion direction of the robot or the release rate of the grouting material is adjusted in real time. According to the iterative scanning-correction cycle, until the filling rate reaches the preset threshold.

[0012] Preferably, after obtaining the grouting filling data by intermittently scanning the post-grouting sample with a low-dose micron-level nano-CT, it further comprises: The micro-nano robot is loaded with iodized oil on the surface, and a mapping relationship between the micron-level nano-CT gray value and the grouting density is established to quantitatively analyze the grouting filling data.

[0013] Preferably, after grouting is completed, it further comprises reloading the post-grouting sample according to a simple loading path to obtain grouting body failure strength data, and checking the convergence condition of the closed-loop correction according to the grouting body failure strength data.

[0014] The application also provides a micro-nano robot grouting system in a true triaxial shear test of rock, comprising: A true triaxial loading device is used to load a rock sample under a true triaxial stress environment to generate a three-dimensional fracture network. A three-dimensional fracture modeling module is used to drive the micro-nano robot to globally scan the fracture topological structure according to the three-dimensional fracture network to obtain a three-dimensional fracture model. A path planning module is used to plan an optimal grouting path of the micro-nano robot according to the three-dimensional fracture model. A micro-nano robot is used to carry out directional grouting on the fracture according to the optimal grouting path to obtain a post-grouting sample. A micron-level nano-CT scanning module is used to obtain grouting filling data by intermittently scanning the post-grouting sample with a low-dose micron-level nano-CT. A parameter adjustment module is used to complete grouting after closed-loop correction of the optimal grouting path or grouting parameter according to the grouting filling data.

[0015] Compared with the prior art, the application has the following advantages and technical effects: The application adopts a complete chain of "true triaxial loading-fracture generation-robot scanning-path planning-directional grouting-micron-level nano-CT closed-loop correction", the whole reinforcement process does not need manual intervention in the fracture, and the micron-level fracture can be accurately filled under complex stress state, so that the test efficiency and grouting success rate are significantly improved.

[0016] The application can repeatedly and controllably generate non-uniform and multi-scale three-dimensional fracture networks through stage loading (first static water, then load increase, and then cycle), so that the fracture characteristics of the indoor sample are highly consistent with the field rock mass, and a real, complex and reproducible fracture sample is provided for subsequent robot path planning.

[0017] The application uses Kine micron-level nano-CT infrared structured light to quickly obtain full-field depth, and then converts the depth into 3D point cloud through an internal parameter matrix, so that the global digitization of millimeter-micron-level fractures can be completed within tens of seconds, and the damage and omission caused by traditional manual sectioning or dyeing description are avoided.

[0018] The application takes "maximum coverage rate + minimum energy consumption" as the goal and couples real-time high-pressure closed-loop avoidance, so that the robot always travels along the lowest resistance and highest demand path in the complex fracture network, reduces repeated scanning and energy waste, and prolongs the service life of the robot in a single operation.

[0019] The application reduces the influence of X-rays on the magnetic core of the robot through intermittent low-dose micron-level nano-CT, and eliminates motion artifacts through the "pause-scan-restart" strategy; through the combination of dual-energy spectrum decomposition and deep learning artifact removal, the robot and the cement slurry can be accurately distinguished, so that the filling rate calculation error is less than 2%.

[0020] The application uses PID closed loop to compare the "micron-level nano-CT measured filling rate" with the "target filling rate" in real time, continuously outputs a correction signal to adjust the robot travel direction and slurry release rate, realizes "measuring while filling, measuring while adjusting", and improves the overall filling rate to more than 90% in one test, avoiding excessive or insufficient grouting.

[0021] The iodized oil preloaded on the surface of the micro-nano robot forms a stable high-brightness mark in the micron-level nano-CT image, after establishing a "gray density" one-to-one mapping, the system can directly use the gray value to invert the slurry filling density, without additional sampling and weighing, greatly shortening the data post-processing time.

[0022] The application continues to apply simple loading until failure after grouting, and obtains the "strength-displacement" curve of the sample after filling; the strength data is fed back to the closed-loop system as a new convergence criterion, so that the PID target value of the subsequent similar rock is automatically corrected, the gap between the test and the safety margin is gradually narrowed, and the reliability of the engineering design is improved. BRIEF DESCRIPTION OF DRAWINGS

[0023] The accompanying drawings, which form a part of the present application, are intended to provide further understanding of the present application and are incorporated herein in conjunction with the description. The accompanying drawings of the present application, together with the description, serve to explain the principles of the present application, and do not constitute improper limitations to the present application. In the drawings: Figure 1 A method flowchart of an embodiment of the present application is shown in the figure; Figure 2 A grouting curve diagram of an embodiment of the present application is shown in the figure; Figure 3 A micro-nano robot structure diagram of an embodiment of the present application is shown in the figure; Figure 4 A true triaxial shear test device diagram of an embodiment of the present application is shown in the figure; Figure 5 A complex stress path diagram of an embodiment of the present application is shown in the figure; Figure 6 A fracture identification diagram of an embodiment of the present application is shown in the figure; Figure 7 A path planning diagram of an embodiment of the present application is shown in the figure; Figure 8 A micro-nano robot precise grouting diagram of an embodiment of the present application is shown in the figure; Figure 9 A true triaxial test loading path diagram of an embodiment of the present application is shown in the figure; Figure 10 A true triaxial shear test device diagram of an embodiment of the present application is shown in the figure; Figure 11 A micro-nano robot grouting into a rock internal passage diagram under a true triaxial pressure state of an embodiment of the present application is shown in the figure. DETAILED DESCRIPTION

[0024] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

[0025] It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a group of computer executable instructions, and although the logical order is shown in the flowchart, in some cases, the steps shown or described herein can be executed in an order different from that shown herein.

[0026] Embodiment one As Figure 1 and Figure 2The embodiment shown relates to a grouting method combined with micro-nanorobot driving, three-dimensional modeling of fissures, dynamic path planning, and real-time verification of micron-level nano-CT, which simulates the stress state of rock in the actual engineering background through the design of a complex path test scheme. Through the development of a complex stress path direct shear test, the fissures generated by the rock are closer to the non-uniform, multi-scale fissure network in natural rock mass, and are suitable for the precise reinforcement of rock containing complex fissures.

[0027] Specifically, the embodiment provides a micro-nanorobot grouting method in a true triaxial shear test of rock, comprising: loading a rock sample under a true triaxial stress environment to generate a three-dimensional fissure network; driving a micro-nanorobot to globally scan the fissure topology according to the three-dimensional fissure network, and obtaining a three-dimensional model of the fissure; planning an optimal grouting path for the micro-nanorobot according to the three-dimensional model of the fissure; controlling the micro-nanorobot to carry out directional grouting on the fissure according to the optimal grouting path, and obtaining a grouted sample; intermittently scanning the grouted sample by a low-dose micron-level nano-CT to obtain grouting filling data; completing grouting after closed-loop correction of the optimal grouting path or grouting parameters according to the grouting filling data.

[0028] The embodiment realizes a closed-loop test of direct shear fissure generation and robot grouting under a true triaxial stress environment, solves the steering problem of micro-nanorobots in narrow fissures through the coordinated control of magnetic field gradients by multiple coils, establishes a mapping relationship between the gray value of micron-level nano-CT images and the grouting density, and realizes quantitative evaluation of the filling effect.

[0029] Further, the process of loading a rock sample under a true triaxial stress environment to generate a three-dimensional fissure network comprises: loading the rock sample to a preset pressure value according to a phased stress ratio : = 2:1:1, which can be adjusted according to actual engineering; obtaining initial fissure expansion according to the loading mode of keeping unchanged, continuously increasing and ; obtaining the final three-dimensional fissure network according to the application of sinusoidal cyclic loading to and .

[0030] Further, a complex stress path test is designed; Stage 1: : =2:1:1, stress increased to =20 MPa, =10 MPa, =10 MPa; Stage 2: and continuously increased, remained unchanged, at this time =30 MPa, =20 MPa, =10 MPa; Stage 3: cyclic loading, and changed in a sinusoidal manner, remained unchanged.

[0031] A true triaxial test was carried out; First, the sample was loaded to hydrostatic pressure state according to the force loading control mode (loading rate was 0.2 MPa / s), =10 MPa, =10 MPa, =20 MPa, at this time remained unchanged, and continuously increased (loading rate was 1 MPa / s) to =30 MPa, =20 MPa, and then cyclic loading (loading rate was 0.5 MPa / s) was carried out, and changed in a sinusoidal manner, remained unchanged.

[0032] Further, according to the three-dimensional fracture network, the micro-nano robot drives the global scanning of the fracture topological structure, and the process of obtaining the three-dimensional model of the fracture includes: A gradient magnetic field generated by multiple coils is used to exert a magnetic force on the robot; The robot is controlled to turn in the narrow fracture by changing the direction of the magnetic field gradient, so as to move along the depth direction of the fracture.

[0033] According to the projection of the infrared structured light by the micro probe carried by the micro-nano robot, a depth map is obtained; According to the depth map and the intrinsic matrix of the micro probe, the pixel coordinates are converted into 3D point cloud; All 3D point cloud data are fused to obtain a three-dimensional model of the fracture.

[0034] Further, after the test is completed, the micro-nano robot drives the scanning of the micro-fracture topological structure of the sample. The micro-nano robot carries a Janus type micro motor, The catalytic end adopts Pt nanoparticles (catalyzing the decomposition of H2O2: 2H2O2→2H2O+O2↑), and the carrier end adopts a porous SiO2 carrier (loading a nano cement paste). The microfluidic chip builds a H2O2 concentration gradient, and the O2 bubbles generated by the catalytic reaction form a local concentration gradient, which drives the movement of the robot (speed 10-50 μm / s).

[0035] The micro-nano robot identifies the fissure through the micro microprobe carried thereon, and a laser scanner scans the fissure with high precision. The micro microprobe uses an infrared structured light projection pattern to capture a deformed pattern and calculate the depth. According to the intrinsic matrix (focal length , , optical center , ) of the Kine micro-nano CT, the depth map is converted into a 3D point cloud: In the formula, u and v are pixel coordinates, and z is a depth value.

[0036] Further, as shown in Figure 6 and Figure 7 , according to the three-dimensional model of the fissure, the process of planning the optimal grouting path of the micro-nano robot includes: establishing a multi-objective function according to the maximum fissure coverage and the minimum robot energy consumption; identifying a high-pressure closed zone according to real-time stress data of the true triaxial; by avoiding the constraint of the high-pressure closed zone, using a fast exploration random tree algorithm to solve the multi-objective function, and obtaining the optimal grouting path.

[0037] Further, the micro microprobe converts the point cloud data to generate a three-dimensional model of the rock surface. Based on the three-dimensional model of the fissure, the optimal path of the micro-nano robot is planned with the goal of maximizing grouting coverage and minimizing robot energy consumption, and the micro-scale directional controllable grouting is performed in combination with the real-time stress data of the true triaxial and by avoiding the high-pressure closed zone.

[0038] Further, as shown in Figure 8 , according to the optimal grouting path, the process of controlling the micro-nano robot to carry out directional grouting on the fissure with the grouting material includes: generating O2 bubbles by the Pt catalytic end of the Janus micro motor carried by the micro-nano robot to obtain a propelling force; controlling the robot speed to be 10-50 μm / s according to the H2O2 concentration gradient established by the microfluidic chip; When the robot reaches the target position, stop the movement by closing the gradient signal, release the nano-cement slurry according to the porous SiO2 carrier, and implement directional grouting on the fracture.

[0039] Specifically, as shown in Figure 3 The micro-nano robot of the embodiment is coated with SiO2 outside the magnetic material Fe3O4 core, which is used to reduce the poor X-ray absorption difference in micron-level nano-CT scanning, and the diameter of the robot is less than the resolution of micron-level nano-CT. The micro-nano robot is loaded with iodized oil on the surface to enhance the contrast of micron-level nano-CT. The micro-nano robot is equipped with a Janus-type micro-motor, the catalytic end uses Pt nanoparticles (catalyzing H2O2 decomposition: 2H2O2→2H2O+O2↑), and the slurry-carrying end uses a porous SiO2 carrier (loading nano-cement slurry). The micro-nano robot is used to scan the fractured rock with high precision by using the micro-probe and laser scanner carried by the micro-nano robot, and a three-dimensional fracture model of the rock surface is generated.

[0040] The core-shell structure of the micro-nano robot of the embodiment is Fe3O4@SiO2, and the overall diameter is less than the resolution of micron-level nano-CT. According to this structure, the micron-level nano-CT artifacts are reduced and the positioning accuracy is improved. The robot has sufficient magnetic response to accept external field steering instructions, and does not produce obvious artifacts in the micron-level nano-CT section. The SiO2 shell isolates Fe3O4 from direct contact with the cement slurry, preventing ion exchange from causing magnetic degradation and ensuring that the robot can be used multiple times.

[0041] Specifically, as shown in Figure 4 The main body of the true triaxial device of the embodiment is made of carbon fiber polymer material, and an embedded space is provided at the edge of the pressure plate near each side of the sample to store a thermostat (to prevent slurry solidification), a micro-nano robot, and an adjustable LED array light source installed around. The embedded space is provided with a sliding door, which uses a high-precision linear guide rail, and a spring pre-tightened ball slide between the door body and the guide rail. After the test is completed, the control switch opens the sliding door, and the micro-nano robot starts to move.

[0042] The micro-nano robot of the embodiment uses the micro-probe and laser scanner carried by the micro-nano robot to scan the fractured rock with high precision, obtains global three-dimensional data, generates a complete three-dimensional fracture model through data fusion, plans an optimal path based on the fracture model, avoids obstacles, and ensures that the robot can reach the target area for accurate grouting. The grouting effect is verified by using a micron-level nano-CT device. During this period, multiple robots work cooperatively to improve the grouting efficiency. The deep data obtained by the micro-probe is used to observe the grouting situation, and the grouting parameters and path are adjusted in real time. After the grouting is completed, the robot withdraws.

[0043] The micro-nano robot in this embodiment has a small volume and strong penetration ability, can enter the rock fracture more effectively, and realize precise control of the grouting process. Through the control of the motion trajectory and position of the micro-nano robot, it can ensure that the grouting material accurately reaches the deep part of the fracture and is released at the necessary position and time, thereby optimizing the reinforcement effect of the rock and reducing the problem of excessive grouting or uneven grouting.

[0044] The Janus micromotor of this embodiment relies on Pt to catalyze H2O2 to generate micro-bubbles for self-propulsion, without external cables or magnetic dragging, and can achieve uniform motion at 10-50 μm / s in a fracture with a width of only tens of microns; the porous SiO2 slurry carrying end realizes the release of slurry at a fixed point and a fixed amount, ensuring that the deep part of the fracture is also fully filled.

[0045] Further, the process of obtaining grouting filling data by intermittently scanning the grouted sample at a low dose of micrometer-level nano-CT includes: Pause the robot motion before scanning, and distinguish the micro-nano robot from the fracture according to the dual-energy micro-CT decomposition; According to the deep learning artifact removal algorithm, high-confidence grouting filling data is obtained.

[0046] Further, this embodiment adopts intermittent low-dose micrometer-level nano-CT scanning, high-resolution micrometer-level nano-CT three-dimensional reconstruction to compare the fracture filling rate before and after grouting, and corrects the robot path or grouting parameters through a feedback control system (PID adjustment) until the grouting is completed and the micro-nano robot returns autonomously. Pause the robot motion before scanning to avoid moving causing image artifacts. In the later image processing, the robot and the fracture are distinguished by dual-energy decomposition, and deep learning image artifact removal is used.

[0047] Further, as shown in Figure 5 According to the grouting filling data, after closed-loop correction of the optimal grouting path or grouting parameters, the process of completing grouting includes: According to the PID controller, the filling rate deviation is calculated to obtain the correction amount; According to the correction amount, the robot motion direction or slurry release rate is adjusted in real time; According to the iterative scanning-correction cycle, until the filling rate reaches the preset threshold.

[0048] The iterative scanning-correction cycle sets the filling rate ≥ 90 % as the termination condition, updates the fracture model and filling distribution data after each grouting is completed, and repeats the planning-grouting-scanning-adjustment closed loop until the entire fracture network meets the termination condition.

[0049] Further, after obtaining the grouting filling data by intermittently scanning the grouted sample at a low dose of micrometer-level nano-CT, it further includes: Iodized oil was loaded onto the surface of micro-nano robots, and a mapping relationship was established between the micron-level nano-CT gray value and the grouting density to quantitatively analyze the grouting filling data.

[0050] Furthermore, such as Figure 9 As shown, after grouting is completed, the process also includes reloading the grouting sample according to a simple loading path to obtain the failure strength data of the grout body, and verifying the convergence condition of the closed-loop correction based on the failure strength data of the grout body.

[0051] Specifically, a simple loading test was conducted on the grouted rock. Loaded to 10MPa Loaded to 20MPa , remain unchanged. Loading continued until the grout body failed, and then the strength characteristics of the grout body were analyzed.

[0052] Example 2 like Figure 10 and Figure 11 As shown, based on the same inventive concept, this embodiment also provides a micro / nanorobotic grouting system for true triaxial shear testing of rocks, comprising: A true triaxial loading device is used to apply complex stress paths to rock samples under true triaxial stress conditions to generate a three-dimensional fracture network. The 3D fracture modeling module is used to drive micro-nano robots to perform a global scan of the fracture topology based on the 3D fracture network to obtain a 3D fracture model. The path planning module is used to plan the optimal grouting path for the micro-nano robot based on the three-dimensional model of the fracture. Micro-nano robots are used to carry grout material to perform directional grouting on cracks according to the optimal grouting path, and obtain grouting samples. The micron-level nano-CT scanning module is used to obtain grouting filling data by intermittently scanning grouting samples with low-dose micron-level nano-CT. The parameter adjustment module is used to complete the grouting process by making closed-loop corrections to the optimal grouting path or grouting parameters based on the grouting filling data.

[0053] Furthermore, the true triaxial loading device of this embodiment is used to apply complex stress paths to rock samples; wherein, the true triaxial loading device includes a pressure plate made of carbon fiber polymer, the edge of the pressure plate is provided with an embedded space for storing micro-nano robots and a constant temperature chamber, the embedded space is provided with a sliding door, the sliding door is opened and closed by a high-precision linear guide rail and a spring-preloaded ball slider.

[0054] Furthermore, the three-dimensional crack modeling module in this embodiment includes: Miniature microprobes are used to project infrared structured light and capture deformed patterns to calculate depth data; Laser scanners are used to acquire high-precision geometric data of cracks; The data processing unit is used to generate a three-dimensional point cloud of the rock surface based on the depth data and geometric data, and to construct a three-dimensional model of the fracture.

[0055] Furthermore, the path planning module in this embodiment is used to plan the optimal motion path of the micro-nano robot based on the three-dimensional model of the fracture, with the goal of maximizing grouting coverage and minimizing robot energy consumption; combined with true triaxial stress data, it avoids high-pressure locked areas and realizes microscale directional controllable grouting.

[0056] Furthermore, the micro-nano robot of this embodiment is used to move in the fractures of the rock sample and perform grouting operations; wherein, the micro-nano robot includes: an Fe3O4 magnetic core; a SiO2 shell for reducing the difference in X-ray absorption during micron-level nano-CT scanning; and a Janus-type micromotor including a catalytic end and a grout-carrying end, wherein the catalytic end uses Pt nanoparticles to catalyze the decomposition of H2O2 to generate O2 bubbles to drive the robot's movement, and the grout-carrying end uses a porous SiO2 carrier for loading nano-cement grout.

[0057] The micro-nano robot constructs an H2O2 concentration gradient using a microfluidic chip, and utilizes the O2 bubbles generated by the catalytic reaction to form a local concentration gradient, propelling the robot to move in the crack at a speed of 10–50 μm / s.

[0058] Furthermore, the micron-level nano-CT scanning module in this embodiment is used to perform intermittent low-dose micron-level nano-CT scans on rock samples before and after grouting to acquire three-dimensional image data; image processing is used to distinguish between micro-nano robots and fracture structures, and to evaluate the grouting filling rate.

[0059] Furthermore, in this embodiment, the parameter adjustment module uses PID control to correct the motion path and grouting parameters of the micro-nano robot in real time based on the image data provided by the micron-level nano-CT scanning module; the robot's movement is paused before the micron-level nano-CT scan to avoid image artifacts.

[0060] Furthermore, the system described in this embodiment also includes: The feedback control unit is used to adjust the grouting strategy in real time based on micron-level nano-CT image data during the grouting process; The autonomous return module is used to control the micro-nano robots to return to their initial position after grouting is completed.

[0061] The embodiment designs a complex stress path test for the system, including hydrostatic pressure loading, differential stress loading and cyclic loading stages; after the test ends, the micro-nano robot scans and grouts the rock sample; the grouting effect is evaluated by micron-level nano-CT scanning, and the strength characteristics of the grouting body are analyzed by loading test.

[0062] The micro-nano robot grouting system in the rock true triaxial shear test provided by the embodiment has all the advantages of the micro-nano robot grouting method provided by the first embodiment.

[0063] Embodiment three The embodiment also discloses a computer device, including a memory, a processor and a computer program stored in the memory, and the processor executes the computer program to realize the steps of the method in the first embodiment.

[0064] Embodiment four The embodiment also discloses a computer readable storage medium, which stores a computer program, and the computer program is executed by a processor to realize the steps of the method in the first embodiment.

[0065] Embodiment five The embodiment also discloses a computer program product, which includes a computer program, and the computer program is executed by a processor to realize the steps of the method in the first embodiment.

[0066] The above is only the preferred specific embodiment of the present application, but the protection scope of the present application is not limited to this, any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method for micro-nano robot grouting in rock true triaxial shear test, characterized in that, The method comprises the following steps: a three-dimensional fracture network is generated by loading a rock sample under a true triaxial stress environment and a complex stress path; a micro-nano robot is driven to globally scan a fracture topology according to the three-dimensional fracture network, and a three-dimensional fracture model is obtained; an optimal grouting path of the micro-nano robot is planned according to the three-dimensional fracture model; the micro-nano robot is controlled to carry out directional grouting on the fracture according to the optimal grouting path, and a grouted sample is obtained; grouting filling data is obtained by intermittently scanning the grouted sample at a low dose and in a micron level; grouting is completed after the optimal grouting path or grouting parameters are corrected in a closed loop according to the grouting filling data.

2. The method of claim 1, wherein the process of generating a three-dimensional fracture network by loading a rock sample under a true triaxial stress environment and a complex stress path comprises:

3. The method of claim 1, wherein the process of driving a micro-nano robot to globally scan a fracture topology according to the three-dimensional fracture network and obtaining a three-dimensional fracture model comprises: According to the stage stress ratio : =2:1:1 rock sample is loaded to a preset pressure value; According to the holding unchanged, continue to increase and loading mode, get the initial crack propagation; According to the method of the present application, the final three-dimensional fracture network is obtained by applying a sinusoidal cyclic loading. and The final three-dimensional fracture network is obtained by applying a sinusoidal cyclic loading. a depth map is obtained by projecting an infrared structured light by a micro probe carried by the micro-nano robot; pixel coordinates are converted into 3D point clouds according to the depth map and an intrinsic matrix of the micro probe; all 3D point cloud data is fused to obtain the three-dimensional fracture model.

4. The method of claim 1, wherein the process of planning an optimal grouting path of the micro-nano robot according to the three-dimensional fracture model comprises: a multi-objective function is established according to maximum fracture coverage and minimum robot energy consumption; a high-pressure closed zone is identified according to real-time true triaxial stress data; the optimal grouting path is obtained by solving the multi-objective function by avoiding the constraint of the high-pressure closed zone.

5. The method of claim 1, wherein the process of controlling the micro-nano robot to carry out directional grouting on the fracture according to the optimal grouting path and obtaining a grouted sample comprises: a propelling force is obtained by decomposing H2O2 to generate O2 bubbles by a Pt catalytic end of a Janus micro motor carried by the micro-nano robot; the robot speed is controlled to be 10-50 μm / s according to an H2O2 concentration gradient established by a microfluidic chip; nano cement grout is released by a porous SiO2 grout-carrying end to implement directional grouting on the fracture.

6. The method of claim 1, wherein the process of obtaining grouting filling data by intermittently scanning the grouted sample at a low dose and in a micron level comprises: robot movement is paused before scanning, and micro-nano robots and fractures are distinguished according to double-energy spectrum micron-level nano-CT decomposition; high-confidence grouting filling data is obtained according to a deep learning de-artifact algorithm.

7. The method of claim 1, wherein the process of completing grouting after the optimal grouting path or grouting parameters are corrected in a closed loop according to the grouting filling data comprises: a correction amount is obtained by calculating a filling rate deviation according to a PID controller; the robot movement direction or the grout release rate is adjusted in real time according to the correction amount. ​ ​ ​ ​ ​ ​ According to the iterative scanning-correction cycle, until the filling rate reaches the preset threshold.

8. The method of claim 1, wherein, After obtaining the grouting filling data by intermittently scanning the grouted sample with a low-dose micronano-CT, the method further comprises: The micro-nano robot is loaded with iodized oil on the surface, and a mapping relationship between the micronano-CT grayscale value and the grouting density is established to quantitatively analyze the grouting filling data.

9. The method of claim 1, wherein, After grouting is completed, the method further comprises reloading the grouted sample according to a simple loading path to obtain grouting body failure strength data, and checking the convergence condition of the closed-loop correction according to the grouting body failure strength data.

10. A micro-nano robot grouting system in a true triaxial shear test of rock, characterized in that, Comprise: A true triaxial loading device for loading a rock sample under a true triaxial stress environment to generate a three-dimensional fracture network; A three-dimensional fracture modeling module for driving the micro-nano robot to globally scan the fracture topological structure according to the three-dimensional fracture network to obtain a three-dimensional fracture model; A path planning module for planning an optimal grouting path of the micro-nano robot according to the three-dimensional fracture model; A micro-nano robot for carrying grouting material to implement directional grouting on the fracture according to the optimal grouting path to obtain a grouted sample; A micronano-CT scanning module for obtaining grouting filling data by intermittently scanning the grouted sample with a low-dose micronano-CT; A parameter adjustment module for completing grouting after closed-loop correction of the optimal grouting path or grouting parameters according to the grouting filling data.

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