Indoor Experiments Research Articles

Research on optimization of engineering parameters of effective action distance of multi-stage alternating injection acid etching

This study calibrated the numerical simulation model by using indoor experiments to measure experimental data related to conductivity, acid rock reaction kinetics and acid fluid loss, and combined it with the numerical simulation model to calculate the multi-condition acid flow under multi-physics coupling . The effective action distance of the acid liquid is finally formed, which can be used at 200℃ and 250℃. The effective action distance of the acid liquid is related to the amount of acid liquid and the number of acid liquid injection stages. A set of quick diagrams that can be quickly applied to multi-stage Alternate injection process design and optimized workflow. After calculation, it is concluded that: for the 200℃ formation, it is recommended that the total amount of acid used in the level 3 injection process should be more than 400m3; if level 2 injection is used, taking into account both cost and benefit, the total acid amount of 300m3 can be close to the same amount of acid in level 3 The effective range of the injection. For the 250℃ formation, it is not recommended to use a solution with small liquid volume and multiple stages. If level 3 injection is used, it is recommended that the acid dosage be more than 500m3; if level 2 injection is used, taking into account both benefits and costs, it is recommended to use 400m3 acid liquid . Injection can obtain an effective distance similar to that of level 3 injection with the same amount of acid.

Effects of Biochar-loaded Ammonia Nitrogen on Soil Carbon Emissions, Enzyme Activity, and Microbial Communities

The form of soil nitrogen input significantly affects soil CO2 emission. As a new form of nitrogen input, biochar-loaded ammonia nitrogen not only reduces the input of chemical nitrogen fertilizer in farmland but also reduces the cost of environmental treatment. It is of great significance to promote the zero growth of national chemical fertilizer, the prevention and control of farmland non-point source pollution, and the realization of the national goal of "carbon peak" and "carbon neutralization." Through an indoor culture experiment, the effects of different nitrogen input forms on soil carbon emission, enzyme activity, and microbial community were studied through four treatments:no fertilization (CK), single application of chemical nitrogen fertilizer (CF), biochar combined application of chemical nitrogen fertilizer (BF), and biochar-loaded ammonia nitrogen (BN). The results showed that compared with that in CF, BF significantly increased cumulative carbon emissions (66.24 %), whereas BN had no significant difference. It is worth noting that the cumulative carbon emissions were significantly reduced by 35.28 % compared with that in BF and BN. Compared with those in CF and BF, the activities of β-glucosidase, peroxidase, and polyphenol oxidase treated with BN significantly increased by 20.25 % and 5.20 %, respectively. Compared with that in CF, the BF treatment increased microbial community richness and community diversity, whereas the BN treatment decreased microbial community richness. Compared with that in BF, the relative abundance of Proteobacteria decreased by 11.16 %, and the relative abundance of Actinobacteria and Bacteroidota increased by 8.12 % and 5.83 %, respectively, in which xylosidase activity was the most important soil factor affecting microbial community structure. The relative abundance of Chloroflexi was significantly correlated with cellobiose hydrolase activity, and the relative abundance of Gemmatimonadetes was significantly correlated with β-glucosidase activity. There was a very significant correlation between the relative abundance of Proteobacteria and cumulative carbon emissions. To summarize, compared with those under biochar combined with chemical nitrogen fertilizer, biochar loaded with ammonia nitrogen significantly reduced cumulative carbon emissions, and its emission reduction effect was better. The results of this study will be beneficial to the landing of the national "double carbon strategy," the healthy development of the biological natural gas industry, the construction of the national green cultivation circular agriculture system, and the realization of the national zero growth strategy of chemical fertilizer.

Sub-frame timestamping of a camera network using a coded light signal

To extract the 3D displacements of structures using a camera network, it is essential to know the frame timestamps. However, technical constraints in outdoor conditions can make synchronous frame acquisition impossible. This study aims to reconstruct the timestamps of frames during post-processing to employ cameras without special camera feature. To achieve this, a LED panel that emits a coded light signal is placed in the field of view common to all cameras. The pixel intensity of the LED region in the sequential images is processed to reconstruct each frame’s timestamp. The uncertainty of the timestamp reconstruction is numerically estimated to encode the light signal. Validation was conducted through indoor experiments and outdoor applications to monitor a tower crane. The uncertainty of the obtained timestamp is 1.65% of the frame interval under uncontrolled conditions. The proposed method can be used with cameras, even when synchronization is unattainable.

Research on Response Characteristics of GPR Method for Detecting Phreatic Lines in Embankments

The excessive elevation of the phreatic lines under continuous high-water levels is the cause of many dangerous situations in embankments. Therefore, accurately understanding the dynamic changes in the infiltration characteristics of embankments is of great significance for judging and evaluating the stability of engineering. This study conducted indoor model experiments and used ground penetrating radar to detect the phreatic lines of soil. By comparing the radar detection results with the measured position of the phreatic lines, it was determined that the phreatic lines appeared as a continuous strong reflection surface with similar shapes in the radargram, and the reflection below the reflection surface became weaker. Through time-domain analysis of the single waveform at different time points, it was found that the amplitude of the reflected wave at the saturation line was larger, and the energy attenuation below the saturation line was faster, resulting in a rapid decrease in amplitude; perform Fourier transform on a single channel signal to obtain a spectrogram, and perform frequency domain analysis on it. The main frequency is around 600MHz, and the second main frequency is around 900MHz. As the saturation line rises, the main frequency gradually shifts towards lower frequencies.

Water vapor condensation prevention and risk rating evaluation based on Yang Can’s tomb

Temperature and humidity variations in burial stone relics can easily cause water vapor condensation, which is an important factor leading to their deterioration. However, the water vapor condensation mechanism and the evaluation of risk ratings have always been difficult problems in the protection of cultural relics. In this study, the water vapor condensation mechanism in Yang Can's tomb was comprehensively investigated through on-site monitoring, indoor experiments and software simulations, on the basis of which a physical model of water vapor condensation in this tomb was established and a water vapor condensation risk rating assessment method was proposed. The proposed method considers the difference between the dew point and wall temperatures within the tomb (dew–wall temperature difference) and the duration of water vapor condensation, and corresponding preventive and control measures were formulated for different risk ratings. The study revealed that when the wall temperature of the chamber is lower than the dew point temperature, water vapor starts to condense. The larger the dew–wall temperature difference is, the greater the risk of condensation. In addition, specific water vapor condensation prevention and control measures were proposed for Yang Can's tomb, and the prevention and control effects were simulated. The simulation results showed that favorable prevention and control effects could be achieved, and the proposed measures could be applied in practice. This study holds notable significance for investigating the water vapor condensation mechanism and evaluating the risk ratings of burial stone relics and provides a theoretical basis and reference for water vapor condensation prevention and control in burial stone relics.

Study on depth weakening of reinforced concrete piles cutting by abrasive waterjets under submerged conditions

In order to improve the efficiency and safety of shield machine cutting reinforced concrete piles, abrasive waterjets (AWJs) assisted mechanical combined cutting technology is considered a feasible solution. However, the water-rich flooding environment will cause the cutting performance of AWJs to weaken, which brings great challenges to the application of this technology. In order to analyze the influence of submerged conditions on the cutting performance of AWJs, the cross-sectional morphology of reinforced concrete piles cut by AWJs is explored using indoor experiments, and the weakening law of pile foundation cutting depth is revealed. The results show that the submerged environment greatly weakens the cutting ability, and the average cutting depth is reduced by about 20.0%. Rebar materials are more difficult to remove due to their high strength and strong plastic toughness, which is the root reason of the difficulty in cutting off piles. As the cutting times increases, the cutting depth discount factor initially decreases rapidly before stabilizing. At 380 MPa, the cutting depth discount factor remains stable at 0.49, while at 280 MPa, it stabilizes at 0.62. The findings presented in this paper can provide guidance and suggestions on waterjet parameters for AWJs assisted shield machine pile breaking. HIGHLIGHTS The cross-sectional change rules of reinforced concrete pile foundation cut by abrasive waterjets is clarified. The depth weakening effect of pile foundations cut by abrasive waterjets under submerged conditions is revealed. The cutting depth discount factor for rebars is established.

Effects of the Mixed Seeding Rate of Milkvetch on Fertilizer Substrate, Growth, and Carotenoid Levels of Baby Leaf Vegetables in Vertical Indoor Farming

During this study, an indoor experiment was conducted to determine the effect of mixed seeding rates of legumes used as green manure on the substrate fertilizer, growth characteristics, and bioactive compounds of baby leaf vegetables. The mixed seeding treatment was designed for milkvetch (Astragalus sinicus L.), tatsoi (Barassica rapa L.), kale (Brassica oleracea var. sabellica L.), and spinach (Spinacia oleracea L.) using five rates for each. Accordingly, a total of 15 treatments (3 baby leaf species × 5 mixed seeding rates) were constructed using a randomized complete block design with three replications for each treatment. During the baby leaf vegetable harvest, we evaluated the macronutrient levels (nitrogen, phosphorus, and potassium) in the substrate as well as the growth parameters and carotenoid contents. The substrate in the treatment mixed with milkvetch showed significantly higher levels of nitrogen, phosphorus, and potassium compared with those of tatsoi and kale sown alone (P ≤ 0.05). However, there were no significant differences in macronutrients observed in substrate-sown spinach with or without the milkvetch mixture. The growth and carotenoid levels of each baby leafy vegetable sown alone were significantly higher than those of each baby leafy vegetable sown with the mixed seeding treatment (P ≤ 0.05). Sowing the milkvetch–vegetable mixtures did not result in a significant increase in the growth and carotenoid levels of the three baby vegetables. The results showed that planting milkvetch with tatsoi and kale had a significant impact on substrate fertilization. However, regarding short-term vertical indoor farming, the growth and carotenoid responses of the three greens may be different. Nonetheless, we still believe that the combined interactions of legumes can provide long-term benefits by enhancing the biological functionality of the growing medium for balanced indoor agriculture production.

Efficient placement technology of proppants based on structural stabilizers

Fiber is highly escapable in conventional slickwater, making it difficult to form fiber-proppant agglomerate with proppant and exhibit limited effectiveness. To solve these problems, a novel structure stabilizer (SS) is developed. Through microscopic structural observations and performance evaluations in indoor experiments, the mechanism of proppant placement under the action of the SS and the effects of the SS on proppant placement dimensions and fracture conductivity were elucidated. The SS facilitates the formation of robust fiber-proppant agglomerates by polymer, fiber, and quartz sand. Compared to bare proppants, these agglomerates exhibit reduced density, increased volume, and enlarged contact area with the fluid during settlement, leading to heightened buoyancy and drag forces, ultimately resulting in slower settling velocities and enhanced transportability into deeper regions of the fracture. Co-injecting the fiber and the SS alongside the proppant into the reservoir effectively reduces the fiber escape rate, increases the proppant volume in the slickwater, and boosts the proppant placement height, conveyance distance and fracture conductivity, while also decreasing the proppant backflow. Experimental results indicate an optimal SS mass fraction of 0.3%. The application of this SS in over 80 wells targeting tight gas, shale oil, and shale gas reservoirs has substantiated its strong adaptability and general suitability for meeting the production enhancement, cost reduction, and sand control requirements of such wells.

Application of Membrane Separation Technology in Electroplating Wastewater Treatment and Resource Recovery: A Review

The rapid development of industry has led to the generation of a large amount of electroplating wastewater. The direct discharge of untreated electroplating wastewater may lead to the formation of toxic metal-organic complexes, which is a challenging problem for human health and the living environment of organisms. Due to the high solubility of heavy metals in aquatic environments and their easy absorption by organisms, effective treatment of electroplating wastewater is of great significance. The ultimate goal of electroplating wastewater treatment should be to recover metals and water from electroplating wastewater. In indoor experiments, pilot tests, and industrial applications of electroplating wastewater treatment, membrane treatment technology commonly used in wastewater terminal treatment has attracted great attention. Membrane treatment technology seems to be the most promising method for removing heavy metals and organic pollutants from electroplating wastewater. This article reviews the membrane treatment technologies for electroplating wastewater, introduces the advantages and disadvantages of various membranes in the treatment of electroplating wastewater, the removal efficiency of pollutant types, and their comparison. The focus is on the treatment effects of nano-filtration membrane, ultra-filtration membrane, micro-filtration membrane, reverse osmosis membrane, ceramic membrane, biofilm, etc., on electroplating wastewater. Compared with a single treatment method, the combination of different processes shows higher efficiency in removing various pollutants.

Stress corrosion phenomenon of casing in CO2 medium and magnetic memory detection

Due to being in an acidic CO2 environment and high-pressure underground, the stress corrosion phenomenon on the inner wall of the CCUS wellbore is more pronounced, with the possibility of wall thickness reduction and crack propagation, which affects the integrity and storage reliability of the wellbore. This article conducted indoor experiments on stress corrosion of oil casing, and characterized the stress corrosion through magnetic memory detection technology. Through experiments, the stress corrosion morphology of specimens under different concentrations, stresses, and defects was obtained. The microstructure of the stress corrosion site was observed using SEM electron microscopy, and the stress corrosion situation of the material in CO2 was observed, laying a foundation for magnetic memory detection; A stress corrosion detection method under CO2 environment was proposed, and the magnetic memory detection method was used to measure that the more severe the stress corrosion, the more obvious the magnetic signal mutation; The shape and morphology of different defects vary, but the main factors affecting magnetic memory signals are concentration and loading force. This article verifies the feasibility of magnetic memory in stress corrosion detection through experiments, and characterizes the stress corrosion situation using magnetic memory signals, which is of great significance for non-destructive testing of wellbore stress corrosion in CO2 storage.

Impact of Mass Flow Rate on Thermal Behavior of PCM-Based SWH during Charging Operations

Using phase change materials in solar water heaters presents an intriguing prospect due to their notable energy density and potential for substantial thermal energy storage capacity. In the context of active-type solar water heaters, careful consideration must be given to the water flow rate as a crucial parameter. This paper investigates the thermal dynamics of active-type solar water heaters equipped with phase change materials, examining variations in mass flow rate during the charging process. Indoor experiments utilized horizontal tanks, flat plate collectors, pumps, and solar simulators. Cylindrical capsules filled with paraffin wax were employed and arranged horizontally within the tank, while K-type thermocouples were utilized to monitor water and paraffin wax temperatures. Charging procedures were executed over 160 minutes with mass flow rate adjustments. Data analysis was performed to evaluate the system's thermal performance during charging. Results indicate higher mass flow rates correspond to increased instantaneous, cumulative heat storage, and charging efficiency. The mass flow rate notably affects the thermal efficiency of solar water heater systems incorporating phase change materials.

Study on multi-stage adjust mechanism of downhole stratification control tool for natural gas hydrate multi-gas combined production gas lift

Accurate control of natural gas flow and pressure is essential to achieving multi-gas combined production of the natural gas hydrates. In this study, a downhole stratification control tool for controlling natural gas flow rate and pressure with a multi-stage throttling structure was innovatively proposed. The multi-stage throttling structure combined an adjustable cage sleeve and a fixed nozzle. The numerical model of the internal flow field of the downhole stratification control tool was established. Through the computer fluid dynamics numerical simulation, the flow field change law inside the spool module of the downhole stratification control tool under different spool structures, different outlet pressures, and different spool openings was analyzed. Moreover, the spool module prototype was processed, and the indoor experiment of the spool's performance of reducing pressure and regulating production was carried out. The results show that the multi-stage throttling structure has the advantages of adjustable spool opening and moderate cooling range and the mass flow of gas inside the spool changes linearly with the opening of the spool. The spool module can accurately control the mass flow of natural gas under high-pressure conditions, and meet the needs of the downhole stratification control tool for accurate gas control.

ULG-SLAM: A Novel Unsupervised Learning and Geometric Feature-Based Visual SLAM Algorithm for Robot Localizability Estimation

Indoor localization has long been a challenging task due to the complexity and dynamism of indoor environments. This paper proposes ULG-SLAM, a novel unsupervised learning and geometric-based visual SLAM algorithm for robot localizability estimation to improve the accuracy and robustness of visual SLAM. Firstly, a dynamic feature filtering based on unsupervised learning and moving consistency checks is developed to eliminate the features of dynamic objects. Secondly, an improved line feature extraction algorithm based on LSD is proposed to optimize the effect of geometric feature extraction. Thirdly, geometric features are used to optimize localizability estimation, and an adaptive weight model and attention mechanism are built using the method of region delimitation and region growth. Finally, to verify the effectiveness and robustness of localizability estimation, multiple indoor experiments using the EuRoC dataset and TUM RGB-D dataset are conducted. Compared with ORBSLAM2, the experimental results demonstrate that absolute trajectory accuracy can be improved by 95% for equivalent processing speed in walking sequences. In fr3/walking_xyz and fr3/walking_half, ULG-SLAM tracks more trajectories than DS-SLAM, and the ATE RMSE is improved by 36% and 6%, respectively. Furthermore, the improvement in robot localizability over DynaSLAM is noteworthy, coming in at about 11% and 3%, respectively.

Analisis Tenaga Pesentakan Jet Aliran Pekeliling Terbalik (PJAPT) Ke Atas Pengumpul Fotovolta Terma Suria (PVT) Modul Dwimuka

Although photovoltaic thermal (PVT) offers ascertain of benefits, it also has its own limitations. The efficiency of PVT is diminished due to heat gain experienced by its photovoltaic module when subjected to solar radiation. Jet impingement has been recognised as a highly successful technique for the purpose of cooling solar modules, particularly in the context of bifacial module applications. An energy analysis of a reversed circular flow jet impingement on a bifacial PVT collector was perform through an indoor experiment utilizing a solar simulator. The jet plate outlet was varied into four different configurations: one hole (1h), three holes (3h), four holes (4h) and five holes (5h) to identify the jet plate outlet configuration that contributes to the best energy efficiency. The experiment was carried out using a constant solar irradiance of 900 W/m2 and mass flow rate between 0.01 kg/s to 0.14 kg/s. The study’s findings indicate that configuration 1h exhibited the best photovoltaic efficiency of 11.09%. Additionally, the highest thermal efficiency recorded was 63.2%. In summary, it can be concluded that configuration 1h exhibits an overall photovoltaic thermal efficiency of 74.28% when subjected to a mass flow rate of 0.14 kg/s. This configuration outperforms other jet plate outlet configuration in terms of energy performance.

Study on the Robustness of an Atmospheric Scattering Model under Single Transmittance

When light propagates in a scattering medium such as haze, it is partially scattered and absorbed, resulting in a decrease in the intensity of the light emitted by the imaging target and an increase in the intensity of the scattered light. This phenomenon leads to a significant reduction in the quality of images taken in hazy environments. To describe the physical process of image degradation in haze, the atmospheric scattering model is proposed. However, the accuracy of the model applied to the usual fog image restoration is affected by many factors. In general, fog images, atmospheric light, and haze transmittances vary spatially, which makes it difficult to calculate the influence of the accuracy of parameters in the model on the recovery accuracy. In this paper, the atmospheric scattering model was applied to the restoration of hazed images with a single transmittance. We acquired hazed images with a single transmittance from 0.05 to 1 using indoor experiments. The dehazing stability of the atmospheric scattering model was investigated by adjusting the atmospheric light and transmittance parameters. For each transmittance, the relative recovery accuracy of atmospheric light and transmittance were calculated when they deviated from the optimal value of 0.1, respectively. The maximum parameter estimation deviations allowed us to obtain the best recovery accuracies of 90%, 80%, and 70%.

Application of Hydrus-2D Model in Subsurface Drainage of Saline Soil in Coastal Forest Land—A Case Example of Fengxian, Shanghai

The study aims to explore saline drainage modeling in coastal saline soils, particularly focusing on subsurface pipe drainage in the Shanghai coastal area. Utilizing Hydrus-2D/3D-2.05 software, dynamic changes in soil–water–salt under various subsurface pipe laying conditions in forested areas were simulated to identify optimal schemes. Indoor and outdoor experiments demonstrated the Hydrus model’s ability to effectively simulate soil–water–salt transport processes under complex conditions. Subsequent simulations under different parameters of underground pipe laying, including burial depths (D = 0.5/0.7/0.9/1.1/1.3/1.5 m) and pipe diameters (Ø = 8/10/12 cm), further corroborated model validation. Among the analyzed schemes, those with burial depths around 0.7 m and pipe diameters under 12 cm exhibited the most substantial salinity improvement. Regression analysis highlighted a significant impact of burial depth D on cumulative salt discharge, with a coefficient of 12.812, outweighing that of pipe diameter Ø. Furthermore, subsurface pipe laying schemes demonstrated long-term benefits and cost advantages, obviating the need for additional irrigation infrastructure. These findings underscore the significance of subsurface pipe drainage in enhancing soil quality, reducing construction expenses, and optimizing land utilization, providing a valuable foundation for the Shanghai Green Corridor development and related initiatives.

Performance Optimization and Experimental Study of Small-Scale Potato-Grading Device

Traditional potato grading in China relies mostly on manual sorting, which is labor-intensive, time-consuming, costly, and inefficient. To enhance the operational performance of potato-grading devices, this paper focuses on optimizing the slide rail structure, which is the key component of a self-developed first-generation potato-grading device. A five-factor, three-level orthogonal experiment was designed, with the experimental factors being the height of the horizontal slide rail, angle of the first-stage inclined slide, angle of the second-stage inclined rail, chain horizontal movement speed, and conveyor belt speed. The indoor experiments were conducted using grading accuracy and grading efficiency as the experimental indicators. On the basis of the analysis of the orthogonal experiment results, two relatively optimal solutions were obtained, and validation experiments were conducted. The validation results show that when the height of the horizontal slide rail was 185 mm, the angle of the first-stage inclined rail was 4°, the angle of the second-stage inclined rail was 2.5°, the horizontal movement speed of the chain was 700 mm/s, and the movement speed of the conveyor belt was 275.60 mm/s, the performance of the movable rotating plate (MRP)-type grading device for potatoes reached its optimum. At this point, the grading accuracy was 94.88%, and the grading efficiency was 13.9477 t/h. Compared with the first-generation grading device, the optimized grading device achieved an improvement of 3.84% in grading accuracy and 12.94% in grading efficiency. The research methodology provided in this paper serves as a reference for the performance optimization of potato-grading devices.

Research on bearing capacity and stability of deep-water novel combined wellhead based on experimental methods

The combined wellhead has the advantage of high bearing capacity and broad prospects for application in the construction of deep water surface wells; therefore, it is important to conduct relevant research to guide the construction of combined wellheads. The aim of this paper is to study the mechanical characteristics of the combined wellhead in the longitudinal direction and establish the method for real-time calculation of the bearing capacity of the combined wellhead taking into account the effects of installation. The variations of external wall pressure and internal soil pressure during installation and the waiting process of the combined wellhead were investigated by indoor experiments. The installation efficiency of the combined wellhead at different negative pressure conditions was also compared. The experimental results show that the pressure on the outer wall of the combined wellhead facility gradually increases as the depth of the combined wellhead facility increases, and the closer it is to the bottom, the greater the soil pressure. The pressure on the inner soil will increase rapidly during the installation process to almost the same level, while the pressure on the outer soil will increase slightly. During the waiting process of the combined wellhead, as the waiting time increases, the soil damaged during the installation process gradually recovers, and the external wall pressure gradually rises. Moreover, the pressure on the outer wall gradually increases, the pressure on the inner soil decreases slightly leveling off within about 24 h. An appropriate increase in suction pressure facilitates the installation of the combined wellhead, and approximately 2.0 L/min is the optimal option for installation. The computational model developed in this paper and the experimental measurements corroborate each other. These combined wellheads significantly improve the stability of deep water soft-soil well construction and provide a theoretical benchmark for developing oil, gas and hydration in deep water.

A Living Assessment of Different Materials for Stratospheric Aerosol Injection—Building Bridges Between Model World and the Messiness of Reality

AbstractThere are obstacles in better understanding the climate impacts associated with new materials that could be used for Stratospheric Aerosol Injections (SAI), like the lack of an integrated framework that combines climate modeling across scales, laboratory studies and small‐scale field experiments. Vattioni et al. (2023, https://doi.org/10.1029/2023gl105889) explored one aspect of using alternative, non‐sulfate materials for SAI. They investigated how uncertain the response of stratospheric ozone would be to alumina injections for SAI. In their study, they quantify chlorine activation rates in the presence of alumina, and then cascade these uncertainties into estimates of ozone depletion, concluding that alumina might have less detrimental impacts on stratospheric chemistry than sulfate, but with large uncertainties. Their results provide a useful basis upon which future research endeavors combining indoor and outdoor experiments and modeling may be structured to produce robust assessments of SAI impacts, benefits and uncertainties, together with clarifying what kind of research needs to be prioritized.

Uncovering the progressive failure process of primary coal-rock mass specimens: Insights from energy evolution, acoustic emission crack patterns, and visual characterization

The failure and instability of deep coal-rock mass structures, which are influenced by mining disturbances, are major contributors to disasters like rock bursts. This study involved conducting indoor experiments using uniaxial loading test and acoustic emission (AE) experiments on indigenous primary coal-rock mass (PCRM). We utilize chaotic bifurcation based on strain energy to characterize the progressive damage stages of PCRM, demonstrating the chaotic characteristics of energy evolution during the gradual destruction process. The degree of damage resulting from PCRM failure was evaluated by jointly applying P-wave velocity tomography and AE event localization. Additionally, the classification of crack patterns in PCRM was conducted using the RA-AF correlation analysis method. The segmentation boundaries of crack classification patterns were then redefined using the Gaussian mixture model (GMM) algorithm. The research findings indicate that the chaotic bifurcation model of strain energy classifies stress into four stages: the stable region (Ⅰ), the metastable region (Ⅱ), the bifurcation region (Ⅲ), and the chaotic region (Ⅳ). The presence of a low-velocity zone in P-waves may indicate crack accumulation and damage within the system. Additionally, areas with abnormal P-wave velocities exhibit numerous AE events. The crack classification patterns of the four stages undergo an evolution from predominantly tensile cracks to a mixture of tensile and shear cracks, and the GMM algorithm successfully identifies the optimal separation path for crack classification boundaries. We propose an adaptive kernel density estimation (AKDE) algorithm to quantify the spatial distribution of AE events, thus offering a visual representation of the damage patterns at various stages.