Method for testing and analyzing interface bonding performance of double-material interface under action of water pressure

Abstract

The invention discloses a method for testing and analyzing interface bonding performance of a double-material interface under the action of water pressure. Firstly, a composite interface test piece is prepared, a water pressure and displacement monitoring integrated sensor is pre-embedded in the interface position of the composite interface test piece, a water pressure loading pipe is embedded in the composite test piece, step-by-step water pressure loading is carried out on the interface of the composite test piece through a water pressure loading device, loading is carried out in a pressurization-pressure stabilization-pressurization mode, and the composite interface test piece is obtained. In the loading process, deformation, sound signal characteristics and water pressure characteristics in the test process are monitored through whole-process monitoring equipment, finally, data collected in the test process are sorted and analyzed, meanwhile, interface characteristics after the test are digitally extracted, and then damage and cracking mechanisms of an interface under the action of water pressure are analyzed. According to the test method provided by the invention, the RMS value of the interface roughness can be adjusted according to requirements by making the quantitative roughness template, so that the influence of the interface roughness on the interface bonding performance under the action of water pressure can be conveniently and efficiently researched.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of material testing, and particularly relates to a method for testing and analyzing the interfacial bonding performance of a double-material interface under water pressure. BACKGROUND

[0002] With the rapid development of infrastructure construction in China, subway rail transit has become the core carrier of urban public transportation. The subway tunnel / rail infrastructure in coastal areas is affected by groundwater pressure. The performance of the waterproof structure degrades during long-term service, and the tunnel structure deforms and cracks. Water seepage is common in tunnel structures, which causes water pressure to act on the interface position of the tunnel-rail structure, and further causes problems such as cracking, peeling, and voiding of the structure interface. In severe cases, the track structure may arch under the action of water pressure, resulting in shape and position defects of the track structure, which seriously affects the safe operation of trains.

[0003] The interface between the whole track bed and the shield tunnel segment is a weak structure. Compared with the concrete matrix, cracks are more likely to occur and expand from the interface position when the concrete structure is under load, which directly leads to the cracking and destruction of the overall concrete structure. With the rapid development of infrastructure, the importance of civil engineering structure reinforcement and repair is increasingly prominent. Grouting repair, as an important means of non-destructive repair, has been widely used. Repair materials such as epoxy resin, expanded high polymer, and underwater non-dispersive high toughness material are used for repairing cracks in concrete structures.

[0004] The bonding performance of the interface between segment concrete and track bed concrete, the interface between segment concrete and repair material, and the interface between track bed concrete and repair material is the key to ensuring the integrity of the structure. As a weak position of the structure, the interface is prone to damage due to excessive vertical tensile stress under water pressure. Therefore, it is necessary to explore the bonding performance and mechanism of the interface between segment concrete and track bed concrete and repair material under water pressure.

[0005] The above problems can be attributed to the bonding performance of the interface between two materials of different properties under the action of water pressure, which is affected by roughness, dry and wet conditions of the interface, water pressure loading rate and other factors. The bonding performance and failure mechanism of the interface are generally explored through unit test. At present, the experimental study on the damage and failure mechanism of the interface under the action of water pressure is not deep enough at home and abroad. The existing research on the structure cracking caused by water pressure mainly focuses on rock materials, and the research on the interface performance is less, and the influencing factors are also less. At the same time, due to the sealing problem of the water pressure loading of the interface position in the unit test, leakage easily occurs, which leads to loading failure, and seriously restricts the efficiency of the interface bonding performance research. The existing research on the damage of the structure under the action of water pressure still mainly focuses on the damage field of single materials such as rock, and the research on the characterization of the interface bonding performance and the damage and crack propagation of the interface is insufficient. In the monitoring aspect, since the interface is located in the interior of the structure, the traditional monitoring method generally monitors through external visualization, and there are certain deficiencies in the damage and crack propagation monitoring of the internal interface, and the embedding mode of the internal sensor and the size and number of the sensor easily affect the interface performance. SUMMARY

[0006] The present application overcomes the defects of the prior art and provides a test and analysis method for the bonding performance of the interface between two materials under the action of water pressure.

[0007] The technical scheme of the present application is as follows.

[0008] The present application provides a test and analysis method for the bonding performance of the interface between two materials under the action of water pressure, which is used to solve the problems existing in the research on the bonding performance of the interface.

[0009] The test method part includes four parts of composite interface sample preparation, water pressure loading device, whole process monitoring and data analysis.

[0010] First, the composite interface sample is prepared, and the water pressure and displacement monitoring integrated sensor is pre-embedded at the interface position of the composite interface sample. The water pressure loading pipe is embedded in the interior of the composite sample. The water pressure loading device is used to load the interface of the composite sample step by step. The loading is carried out through the methods of pressure increase-stabilization-pressure increase. During the loading process, the non-contact strain monitoring system, the acoustic emission system and the water pressure and displacement monitoring integrated sensor embedded in the interface are used to monitor the deformation, acoustic signal characteristics and water pressure characteristics in the test process.

[0011] The interface sample is composed of a first sample, a pre-crack, a water pressure loading pipe and a second sample. The materials of the first sample and the second sample can be selected according to the requirements. The pre-crack is located at the interface position of the first sample and the second sample, and the material is polystyrene board, the size of which can be selected according to the requirements. The water pressure loading pipe includes a water inlet pipe, an anti-pulling-out component and an internal thread connector.

[0012] First, the first specimen was cast. Sample preparation considered the impact of interface roughness on interfacial bonding performance. A quantitative roughness template model was constructed. After the model was constructed, a template was produced using 3D printing technology. The template allowed for the definition and selection of roughness based on requirements. When the first specimen was cast, the roughness template was placed at the bottom of the mold to form a quantitatively rough surface.

[0013] Prefabricated cracks are achieved by attaching a soluble material to the middle of the surface of the first specimen. A hydraulic loading tube is fixed to the middle of the soluble material. The second specimen is cast on the surface of the first specimen to form an interface composite specimen. The soluble material is located at the interface between the first and second specimens. The hydraulic loading tube is located inside the second specimen. One end of the hydraulic loading tube is connected to the soluble material, and the other end is higher than the upper surface of the composite specimen and is fixed to the internal thread connector. The sample preparation takes into account the influence of interface roughness on interface bonding performance. First, a quantitative roughness template model is constructed. After the model is constructed, a template is produced using 3D printing technology. The template can define and select the roughness according to the needs.

[0014] The hydraulic loading device includes a water tank, a visual control system, a precision water pump, and water inlet and outlet pipes. The water tank is connected to the precision water pump via the inlet pipe. The outlet pipe is connected to the precision water pump at one end and has an external threaded port at the other end, which connects to the internal threaded connector of the hydraulic loading pipe of the composite interface specimen. The visual control system controls the hydraulic loading method.

[0015] The whole process monitoring equipment includes non-contact strain monitoring system, acoustic emission system, and interface water pressure and displacement monitoring system.

[0016] The non-contact strain monitoring system consists of a support, four industrial cameras, and a data acquisition system. The support comprises a base plate, slide rails, sliding brackets, and connecting rods. The four slide rails are located on each side of the base plate. The connecting rods are embedded in the rails and secured in place by bolts on both sides. Two sliding brackets are arranged in parallel, with embedded components and bolts at each end. The embedded components are embedded in the rails, allowing the sliding brackets to slide parallel to each other. Bolts secure the sliding brackets in place. A tightening bolt is installed in the middle of the sliding brackets to secure the specimen. Four industrial cameras are mounted on the four connecting rods of the support. The monitoring head is connected to the data acquisition system via a data transmission line. The data acquisition system is used to store data.

[0017] The acoustic emission system is used for collecting acoustic signals in the hydraulic fracturing process of the composite interface test piece, and the damage mechanism in the test piece is revealed through acoustic signal analysis. It comprises a sensor, a connecting line 1, an amplifier, a connecting line 2, an acoustic emission acquisition device, a signal line and a control end. The sensor is adhered to the surface of the monitored test piece according to the monitoring requirements, the sensor is connected with the amplifier through the connecting line 1, the amplifier is connected with the acoustic emission acquisition device through the connecting line 2, the acoustic emission acquisition device is connected with the control end through the signal line, and the acoustic emission acquisition parameters are set through the control end.

[0018] The interface water pressure and displacement monitoring system comprises a water pressure and displacement monitoring integrated sensor and a signal acquisition instrument. The water pressure and displacement monitoring integrated sensor is embedded in the interface position of the composite interface test piece, and is used for monitoring the water pressure change law of the interface and the interface crack deformation characteristics in the test process. It comprises a displacement meter, a water pressure sensor and a signal line. The displacement meter and the water pressure sensor are connected with the signal acquisition instrument through the signal line (as shown in Figure 10

[0019] Data analysis is used for arranging and analyzing the data collected in the test process, and the interface characteristics after the test are digitized and extracted, and then the damage and cracking mechanism of the interface under the action of water pressure is analyzed. Mainly including interface bonding performance parameter calculation, interface characteristic three-dimensional scanning after test, interface roughness calculation, etc.

[0020] Each roughness and each water pressure loading scheme is tested to obtain a large amount of test data, the test data is deeply analyzed, a large amount of experimental data is trained based on a random forest model, and the interface water pressure peak value is predicted, and the main steps are as follows.

[0021] (1) the initial roughness Sa_initial of the interface, the static water pressure loading rate v_load and the roughness Sa_failure after failure are obtained through standard test;

[0022] (2) calculate the roughness change rate ΔSa = Sa_failure / Sa_initial;

[0023] (3) calculate the roughness evolution index R = (Sa_failure-Sa_initial) / K, wherein K is a standardization constant;

[0024] (4) input the above parameters into the trained random forest prediction model;

[0025] (5) output the interface limit water pressure value P_max and the 95% confidence interval;

[0026] Compared with the prior art, the advantages of the present application are that:

[0027] ​The test method provided by the application can quantitatively manufacture roughness templates, so that the interface roughness RMS value can be adjusted according to requirements, and the influence of the interface roughness on the interface bonding performance under the action of water pressure can be efficiently researched; secondly, through the prefabricated crack and the water pressure loading pipe structure design, the water pressure is ensured to act on the interface position, and the loading failure caused by the water pressure loading pipe being pushed out in the loading process is effectively avoided.

[0028] The monitoring part can ensure the effectiveness of data monitoring and collection in the whole test process through internal, external, acoustic signal and video signal cooperative monitoring, and the monitoring data can be verified with each other to ensure the data accuracy. The water pressure loading can be adjusted according to requirements, the loading rate and loading mode can be customized, and the applicable working conditions of the test are effectively expanded. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 It is a test technical scheme flow chart;

[0030] Figure 2 It is a template picture of different roughness;

[0031] Figure 3 It is a first test block and water inlet pipe connection mode diagram.

[0032] Figure 4 It is a composite interface test piece and polystyrene plate-water pressure loading pipe section view;

[0033] Figure 5 It is a composite interface test piece physical picture;

[0034] Figure 6 It is a test piece installation and part of the monitoring schematic diagram;

[0035] Figure 7 It is a water pressure loading system schematic diagram;

[0036] Figure 8 It is a hydraulic fracturing test data example;

[0037] Figure 9 It is an interface scanning roughness calculation;

[0038] Figure 10 It is a connection schematic diagram of a water pressure and displacement monitoring integrated sensor.

[0039] Figure 4 Each component is as follows: a first test piece 1, a second test piece 2, an internal thread connector 3, a water inlet pipe 4, a sensor signal line 5, an extension screw 6, a sleeve 7, a polystyrene plate 8, a water pressure and displacement monitoring integrated sensor 9. DETAILED DESCRIPTION

[0040] The implementation process of the present application is specifically illustrated by a bonding performance test of a shield segment concrete and a track bed concrete interface composite sample under the action of water pressure.

[0041] Figure 1 The test scheme technical flow chart mainly includes the following steps: constructing a quantitative roughness template model, 3D printing the quantitative roughness template, preparing a first concrete test piece, performing pre-crack treatment, pre-embedding a water pressure loading pipe, preparing a second concrete test piece to form a composite test piece, carrying out a water pressure test, obtaining interface bonding performance, testing the failure interface topography after the test is completed, and performing quantitative characterization; summarizing test data, calculating interface roughness, combining acoustic emission monitoring, external non-contact strain monitoring, internal water pressure and displacement monitoring data, and exploring the interface bonding performance evolution law.

[0042] Test piece preparation: first, construct a quantitative roughness template model; define the parameters of the template, including the length, width, thickness, root mean square height, spectral index and spatial frequency resolution of the template; the length and width determine the size of the generated template, the root mean square height is used to quantitatively measure the roughness of the template, and the spectral index and spatial frequency resolution are used to control the detailed features of the rough surface, i.e. control the smoothness and fluctuation degree of the surface texture; the length and width of the quantitative roughness template can be defined according to requirements, and in this embodiment, the length and width are selected to be 9.8 cm, the root mean square height is defined to be 0.5 cm, the spectral index is set to 25, and the resolution is set to 0.001. Adjust the root mean square height to control the surface roughness of the template, generate a quantitative rough surface after completing the parameter definition, construct a cube with the same length, width and thickness higher than the maximum height difference of the quantitative rough surface, and divide the cube into two parts by dividing the domain, with the lower structure reserved as the template model, and the grid is divided and exported as a.stl format. Different roughness template models are shown in Figure 2 The.stl format model is used to print the quantitative roughness template through a 3D printer.

[0043] The quantitative roughness template is installed on the bottom of the mold with the rough surface facing up, and the mold size can be defined according to requirements. In this embodiment, the mold is a cube triplex mold with a side length of 10 cm. The raw materials are weighed and mixed according to the structure material mixing ratio, and the mixed material is poured into the triplex mold. In this embodiment, the first test block material is selected as C50 concrete, and vibration compaction is performed to form the first test piece. It should be noted that the height of the first test piece is 5 cm.

[0044] The first test piece was demolded after 1 day of pouring and was cured. The quantified roughness surface was used as the top surface of the first test piece, and a prefabricated crack was processed. The prefabricated crack was formed by polystyrene board material, and the polystyrene board material was cut and trimmed into a cube with an edge length of 2.5 cm and a height of 1 cm, or a cylinder with a diameter of 2.5 cm and a height of 1 cm. In this embodiment, the polystyrene board is in the shape of a cube. The upper part of the prefabricated crack polystyrene board is embedded in the water inlet interface end of the water pressure loading pipe, and the two are fixedly connected, with the water inlet interface end being 0.5 cm higher than the bottom of the polystyrene board.

[0045] The water pressure loading pipe is composed of PVC pipes with different lengths and diameters and an internal thread connector, as shown in Figure 4 The PVC pipe with an outer diameter of 1.6 cm and a length of 15 cm is selected as the water inlet pipe. The water inlet pipe, the anti-pulling-out component, and the internal thread connector are connected. The anti-pulling-out component is composed of a sleeve and an extension screw. The sleeve has the same inner diameter as the outer diameter of the water inlet pipe and is fixedly attached to the outside of the water inlet pipe by epoxy resin adhesive. The sleeve is perforated at an interval of 90° on the outside, and the extension screw is fixedly attached to the holes by epoxy resin adhesive. It should be noted that the sleeve is located at a position 2 cm above the interface end of the water inlet pipe, and the height of the sleeve is 1 cm. The water inlet end of the water inlet pipe is fixedly connected to the internal thread connector by epoxy resin adhesive.

[0046] The first test piece was placed in the mold, and the polystyrene board-water pressure loading pipe bottom was attached to the middle position of the top surface of the first test piece by double-sided tape, Figure 3 (the water inlet pipe is not installed with an anti-pulling-out device on the internal thread connector in the figure). Holes were drilled in the middle position of the opposite sides of the prefabricated crack polystyrene board on the surface of the first test piece, and a water pressure and displacement monitoring integrated sensor was installed. The sensor signal line extends from the top of the second test piece.

[0047] Subsequently, the concrete pouring of the second test piece was carried out. The poured test piece is shown in Figure 5 , and the test piece cross-sectional view is shown in Figure 4 .

[0048] After the demolding and curing of the composite interface test piece were completed, the test preparation stage was entered. First, the connection position of the water inlet pipe and the top end of the test piece and the connection position of the water inlet pipe and the internal thread connector were sealed, and transparent epoxy resin adhesive was used for sealing; after the epoxy resin adhesive was cured, 10 mL of polystyrene board dissolving agent was poured into the water inlet pipe of the composite interface test piece to ensure that the polystyrene board was completely dissolved to form a prefabricated crack, and the water inlet pipe and the prefabricated crack area were rinsed with clean water after dissolution.

[0049] The test piece side surface needs to be treated before the test. First, the concrete surface is polished with sandpaper to remove surface stains and ensure the flatness of the concrete surface. White spray paint is used to spray the four side surfaces of the test piece, and then black spray paint is used to make the black spray paint evenly scattered to form black scattered spots.

[0050] The composite interface test sample is placed on the support plate of the support frame, between the two sliding supports, the sliding support is moved to tightly adhere to the surface of the test sample, the bolts on both sides of the sliding support are rotated to fix the position of the sliding support, and the test sample is fixed by rotating the tightening bolts. The installation of the test sample and the arrangement of the monitoring equipment are shown in Figure 6 The position of the industrial camera connecting rod is adjusted so that the industrial camera is directly opposite the side of the test sample. During the test, the acquisition frequency of the industrial camera is set to 120 frames / s.

[0051] In this embodiment, the acoustic emission monitoring equipment uses a DS5 acoustic emission instrument from Beijing Soft Island Times Technology Co., Ltd., including a sensor, a connection line 1, an amplifier, a connection line 2, an acoustic emission acquisition device, a signal line, and a control end. The acoustic emission sensor is adhered to the surface of the test sample according to the monitoring requirements through silicone grease, the acoustic emission sensor is connected to the amplifier through the connection line 1, the amplifier is connected to the acoustic emission acquisition device through the connection line 2, the acoustic emission acquisition device is connected to the control end through the signal line, and the acoustic emission acquisition parameters are set through the control end. Before the test, the lead is broken and positioned, and the material wave speed of the composite interface test sample is measured. During the test, the sensor acquisition frequency is 3 MHz, the acoustic emission signal threshold is set to 40 dB, and the threshold value is set to 10 dB. The acoustic emission sensor is adhered to the four sides of the test sample in a diagonal manner, with two on each side, so that the acoustic emission sensor is located on multiple planes for accurate positioning. The acoustic emission sensor is adhered to the surface of the test sample using vacuum silicone grease.

[0052] The test is loaded by a water pressure loading device, as shown in Figure 7 The water pressure loading device includes a water tank, an inlet pipe, a precision water pump, an outlet pipe, and a visual control system. The outlet pipe of the water pressure loading device is connected to the inner composite interface test sample inner thread connector. Raw material tape is used to wrap the threaded position to ensure the sealing property. Tracer is added in the water before pressurization to study the interface cracking condition. The loading gradient and pressure stabilization time are set through the visual control system. In this embodiment, in order to explore the influence of roughness and loading rate on the interface bonding performance under the action of hydrostatic pressure, five water pressure loading schemes are set, as shown in the following table:

[0053] Table 1 Water pressure loading scheme

[0054] Loading scheme number Lower loading limit Loading interval Stabilization time Upper loading limit 1 0 0.1 30s 3.5 MPa 2 0 0.25 30s 3.5 MPa 3 0 0.5 30s 3.5 MPa 4 0 0.75 30s 3.5 MPa 5 0 Continuous loading 0 3.5 MPa

[0055] After loading, the three-dimensional optical scanning equipment is used to scan the surface of the first test piece of the composite interface test piece to generate a model file in.stl format, and the surface RMS value is calculated. The RMS value calculation process is as follows: first, use matlab software to read the.stl file to obtain the coordinate values of each grid point of the model, remove the macroscopic shape tilt feature, determine the reference surface, calculate the height deviation Zi of each data point item to the reference surface, calculate the square of all deviation values and take the average, and finally take the square root of the average of the square of the deviation value to obtain the RMS value. The RMS value of the first test piece after failure is compared with the initial RMS value to analyze the relationship between the interfacial bonding performance and the roughness under the action of hydrostatic pressure and the failure mode.

[0056] Figure 8 The original interface RMS value is 2.5 mm, and the test data is obtained according to the 0.1 MPa gradient interval and the pressure holding time of 30 s. Under this loading condition, the maximum water pressure that the composite test piece interface can withstand is 2.0 MPa. During the loading process, the water pressure remains stable and rises. During the pressure holding process after the water pressure reaches 2.0 MPa, the composite test piece interface fails, resulting in a sharp drop in water pressure.

[0057] The failed interface is scanned by three-dimensional scanning to obtain the three-dimensional morphology of the failed interface, and the roughness value is calculated, as shown in Figure 9 The data cloud map of the original surface is obtained by scanning the failed interface, and then the reference surface is set or automatically fitted. Based on the reference surface position, the roughness RMS value of the failed interface is calculated.

[0058] Data analysis: After the test is completed, the test piece-pressure curve can be obtained, and the acoustic emission data, industrial camera video data, and interface water pressure and displacement change data can be obtained. All test data are time-unified. The acoustic wave propagation speed of the composite interface test piece is determined by the lead breaking test. The acoustic wave speed is input into the test monitoring data, the acoustic emission monitoring data is played back to obtain the acoustic emission signal positioning point coordinates, and the time is corresponded, so that the interface cracking and expansion characteristics in the test process can be analyzed. The video data obtained is subjected to strain analysis, and the deformation characteristics of the interface under the action of water pressure are revealed by the evolution of the interface strain.

[0059] Each roughness and each water pressure loading scheme is tested to obtain a large amount of test data, which is deeply analyzed. Based on the random forest model, a large amount of experimental data is trained, and the interface water pressure peak value is predicted. The specific implementation includes data acquisition, prediction model construction, model verification, and prediction application.

[0060] (1) The following core data is obtained by standard test:

[0061] Initial roughness (Sa_initial): Initial roughness is the same as the template roughness Loading rate (v_load): 5 loading regimes

[0062] Failure roughness (Sa_failure): After the specimen fails, the interface is rescanned and the roughness RMS value is calculated

[0063] Water pressure peak (P_max): The maximum pressure value recorded by the pressure sensor at the moment of failure is generated according to the following formula:

[0064] Roughness change rate: ΔSa = Sa_failure / Sa_initial

[0065] Roughness evolution index: R = (Sa_failure - Sa_initial) / K (K is a standardization constant, with a value range of 800-1200, and a recommended value of 1000);

[0066] Robust standardization method is used to process data, calculate the median and interquartile range (IQR) of each feature, and perform data conversion: X_scaled = (X-X_median) / IQR, and the conversion parameters are retained for the prediction stage.

[0067] (2) Prediction model construction

[0068] Random forest architecture: The model uses a regression type random forest

[0069] Number of decision trees: 300-700 (determined by cross-validation)

[0070] Tree depth control: Maximum depth of 5-10 layers

[0071] Node splitting rule: Minimum number of split samples 3-5 Hyperparameter optimization uses five-fold cross-validation grid search strategy:

[0072] Define parameter search space:

[0073] Number of trees: {300, 500, 700}

[0074] Maximum depth: {5, 8, 10}

[0075] Feature sampling ratio: {0.7, 0.8, √n_features}

[0076] Evaluation index: Negative mean square error (Negative MSE)

[0077] Select the parameter combination with the highest out-of-bag score

[0078] Model training

[0079] Train / test split at 80:20 ratio

[0080] Ensure uniform distribution of each roughness level in the training set

[0081] Enable out-of-bag (OOB) validation during training.

[0082] (3) Model validation and interpretation

[0083] Performance evaluation metrics

[0084] Coefficient of determination R 2 : Assess model interpretability

[0085] Mean Absolute Error MAE (kPa): Quantify engineering error

[0086] Prediction interval coverage: Proportion of true values contained within 95% confidence interval Feature importance analysis: Use Gini importance calculation method

[0087] Statistical average impurity reduction of each feature in the forest in descending order of importance value

[0088] Output key factor ranking table

[0089] Interaction effect visualization: Achieved through SHAP framework

[0090] Calculate feature contribution value (SHAP value)

[0091] Draw bivariate dependence graph:

[0092] X-axis: Initial roughness

[0093] Y-axis: SHAP value

[0094] Color: Loading rate

[0095] Generate interaction effect heat map.

[0096] (4) Prediction application system (water pressure peak prediction process)

[0097] Input parameters:

[0098] Initial roughness Sa_initial (μm)

[0099] Loading rate v_load (kPa / s)

[0100] Roughness after failure Sa_failure (μm)

[0101] Feature calculation:

[0102] ΔSa = Sa_failure / Sa_initial

[0103] R = (Sa_failure - Sa_initial) / 1000

[0104] Data standardization: Apply pre-stored conversion parameters

[0105] Model prediction: Output P_max point estimate

[0106] Confidence interval: Calculate 95% prediction interval based on forest variance.

[0107] The embodiments of the present application are described in detail above with reference to the accompanying drawings, but the present application is not limited to the above-described embodiments, and various changes can be made within the scope of knowledge of those skilled in the art without departing from the spirit of the present application.

Claims

1. A method for testing and analyzing the interfacial bonding performance of a bimaterial interface under water pressure, characterized in that: The steps include: First, a composite interface specimen is prepared, and an integrated water pressure and displacement monitoring sensor is pre-embedded at the interface position of the composite interface specimen. A water pressure loading tube is buried inside the composite specimen, and a water pressure loading device is used to perform step-by-step water pressure loading on the composite specimen interface. The loading is performed in a pressurization-stabilization-pressurization manner. During the loading process, the deformation, acoustic signal characteristics and water pressure characteristics of the test process are monitored by full-process monitoring equipment. Finally, the data collected during the test are sorted and analyzed, and the interface characteristics after the test are digitally extracted, thereby analyzing the damage and cracking mechanism of the interface under the action of water pressure; the data include the calculation of interface bonding performance parameters, three-dimensional scanning of interface characteristics after the test, and interface roughness calculation.

2. A method for testing and analyzing interface bonding performance of a bi-material interface under water pressure as claimed in claim 1, characterized in that: The composite interface specimen consists of a first specimen, a prefabricated crack, a water pressure loading pipe and a second specimen; the prefabricated crack is located at the interface between the first specimen and the second specimen, and the material of the prefabricated crack is a polystyrene board; the water pressure loading pipe includes a water inlet pipe, an anti-pullout component and an internal thread connector, the internal thread connector is arranged at the top position of the water inlet pipe, and the anti-pullout component is installed in the middle and lower part of the water inlet pipe and is located in the second specimen.

3. A method for testing and analyzing interface bonding performance under water pressure at a bi-material interface as claimed in claim 2, characterized in that: The anti-pulling component is a sleeve.

4. A method for testing and analyzing interface bonding performance of a bi-material interface under water pressure as claimed in claim 1, characterized in that: Water pressure and displacement monitoring integrated sensors are provided on both sides of the prefabricated crack.

5. The method for testing and analyzing the interfacial bonding performance of a bi-material interface under water pressure as claimed in claim 1, characterized in that: The preparation method of the composite interface specimen is as follows: first, a first specimen is cast, and prefabricated cracks are achieved by sticking a soluble material to the middle position of the surface of the first specimen, a water pressure loading tube is fixed to the middle of the soluble material, and a second specimen is cast on the surface of the first specimen to form an interface composite specimen. The soluble material is located at the interface between the first specimen and the second specimen, and the water pressure loading tube is located inside the second specimen. One end of the water pressure loading tube is connected to the soluble material, and the other end is higher than the upper surface of the composite specimen and is fixedly connected to the internal thread connector.

6. A method for testing and analyzing interface bonding performance of a bi-material interface under water pressure as claimed in claim 1, characterized in that: The water pressure loading device includes a water tank, a visual control system, a precision water pump, a water inlet pipe and a water outlet pipe; the water tank is connected to the precision water pump through the water inlet pipe, one end of the water outlet pipe is connected to the precision water pump, and the other end is an external threaded pipe mouth, which is connected to the internal thread connector of the water pressure loading pipe of the composite interface specimen. The water pressure loading mode is regulated by the visual control system.

7. A method for testing and analyzing interface bonding performance of a bi-material interface under water pressure as claimed in claim 1, characterized in that: The whole process monitoring equipment includes a non-contact strain monitoring system, an acoustic emission system, and an interface water pressure and displacement monitoring system; The non-contact strain monitoring system includes a bracket, four industrial cameras, and a data acquisition system. The bracket includes a support frame base plate, slide rails, sliding brackets, and connecting rods. There are four slide rails in total, located on the four sides of the support frame base plate. The bottom of the connecting rod is embedded in the slide rail and fixed in position by bolts on both sides. The two sliding brackets are arranged in parallel, with embedded components and bolts set at both ends. The embedded components are embedded in the slide rails to achieve parallel sliding of the sliding brackets, and the position of the sliding brackets is fixed by bolts. A fastening bolt is installed in the middle of the sliding bracket to fix the position of the test piece; four industrial cameras are installed on the four connecting rods of the bracket respectively, and the monitoring head is connected to the data acquisition system via a data transmission line. The data acquisition system is used to store data; The acoustic emission system is used to collect acoustic signals during the hydraulic fracturing process of a composite interface specimen and to reveal the damage mechanism inside the specimen through acoustic signal analysis. The system comprises an acoustic emission sensor, a connecting line 1, an amplifier, a connecting line 2, an acoustic emission acquisition device, a signal line, and a control terminal. The acoustic emission sensor is adhered to the surface of the monitored specimen using silicone grease according to monitoring requirements. The acoustic emission sensor is connected to the amplifier via connecting line 1. The amplifier is connected to the acoustic emission acquisition device via connecting line 2. The acoustic emission acquisition device is connected to the control terminal via a signal line. The acoustic emission acquisition parameters are set via the control terminal. The interface water pressure and displacement monitoring system includes an integrated water pressure and displacement monitoring sensor and a signal acquisition instrument. The integrated water pressure and displacement monitoring sensor is pre-buried at the interface position of the composite interface specimen and is used to monitor the water pressure change pattern and interface crack deformation characteristics during the test. It includes a displacement meter, a water pressure sensor and a signal line; the displacement meter and the water pressure sensor are respectively connected to the signal acquisition instrument through signal lines.

8. The method for testing and analyzing the interfacial bonding performance of a bi-material interface under water pressure as claimed in claim 1, characterized in that: Experiments were conducted on various roughness and water pressure loading schemes to obtain a large amount of test data. The test data was deeply analyzed and trained based on the random forest model to predict the peak interface water pressure. The main steps are as follows: (1) Obtain the initial roughness Sa_initial, hydrostatic pressure loading rate v_load and post-failure roughness Sa_failure of the interface through standard tests; (2) Calculate the roughness change rate ΔSa = Sa_failure / Sa_initial; (3) Calculate the roughness evolution index R = (Sa_failure-Sa_initial) / K, where K is the normalization constant; (4) Input the above parameters into the trained random forest prediction model; (5) Output the interface ultimate water pressure value P_max and 95% confidence interval.

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