Emission Testing Research Articles

Flexural failure of ultra-high performance concrete subjected to the alternating cryogenic and elevated temperature via acoustic emission characterization

This paper aims to reveal the mechanical evolution and potential mechanism of Ultra-high Performance Concrete (UHPC) exposed to a complex temperature-variation environment typical of Liquefied Natural Gas storage tank. Herein, the effect of steel fiber geometries (straight and hooked-end) on flexural failure of UHPCs in the range of −170 °C ∼ 200 °C was studied, and dynamic fracture evolution during the loading process was tracked using acoustic emission (AE) test. Results indicated that the flexural strength of concrete specimen enhanced at −170 °C but diminished at 200 °C in the first cycle. For multiple cycles, its improved strength subsisted until the third cycle, after which gradually decreased. Moreover, the hooked-end fiber generally had superior strengthening and toughening effects than straight fiber, except for cryogenic temperature and third cycles tests. At cryogenic temperature, the freezing of pore moisture inside specimen enhanced the matrix strength and the interfacial bonding between the matrix and fibers. At elevated temperature, the thawing, diffusion and evaporation of moisture in concrete could induce matrix dehydration and weaken the bonding effect between interfaces. In varying exposure environments, the moisture migration would also undergo secondary hydration reactions with unreacted cement particles. Finally, using AE parameters to effectively record damage progression in UHPCs exposed to extreme temperatures was also highlighted.

Design of PMN-PT-based dual-resonance acoustic emission sensor for partial discharge detection

This paper presents the design, fabrication, and testing of a dual-resonance acoustic emission (AE) sensor based on PMN-PT single crystal for partial discharge (PD) detection. The use of high-performance PMN-PT single crystal enhances the sensor sensitivity. Resonance peak coupling is utilized to increase the bandwidth of the sensor effectively. The effects of piezoelectric vibrator size, vibrator spacing, and external circuitry on the sensor output are analyzed using equivalent circuits and finite element models (FEM) for sensor design. After calibration, the self-made sensor has a peak sensitivity of 76.4 dB and a bandwidth of 20 kHz to 150 kHz, which meets the demand of PD detection. The PD detection experiments verify that the self-made sensors can accurately detect PD with a high signal-to-noise ratio of 15.8 dB. In the end, the reliability test proves that the sensors have good stability and temperature characteristics. Besides above sensor’s performance improvement, our design has the great potential to reduce the sensor’s cross section, resulting better suitability on curved surfaces. The feasibility of employing PMN-PT as a replacement for PZT in the fabrication of AE sensors is proven by these good test results.

Creep damage constitutive model of rock based on the mechanisms of crack-initiated damage and extended damage

Since the classical element model cannot describe the nonlinear characteristics of rock during the entire compressive creep process, nonlinear elements and creep damage are generally introduced in the model to resolve this issue. However, several previous studies have reckoned that creep damage in rock only occurs in the accelerated creep stage and is only described by the Weibull distribution. Nevertheless, the creep damage mechanism of rocks is still not clearly understood. In this study, a reasonable representation of the damage variables of solid materials is presented. Specifically, based on the Gurson damage model, the damage state functions reflecting the constant creep stage and accelerated creep stage of rock are established. Further, the one-dimensional and three-dimensional creep damage constitutive equations of rock are derived by modifying the Nishihara model. Finally, the creep-acoustic emission tests of phyllite under different confining pressures are conducted to examine the creep damage characteristics of phyllite. And the proposed constitutive model is verified by analyzing the results of creep tests performed on saturated phyllite. Overall, this study reveals the relationship between the creep characteristics of rocks and the corresponding damage evolution pattern, which bridges the gap between the traditional theory and the quantitative analysis of rock creep and its damage pattern.

Experimental investigation of the polarity-switching process with different bipolar ionic liquid thruster operating frequencies

The bipolar ionic liquid thruster employs ionic liquid as a propellant to discharge positively and negatively charged high-energy particles under an alternating current (AC) power source, effectively suppressing electrochemical reaction and ensuring charge neutrality. Determining an optimal AC supply power source frequency is critical for sustained stable thruster operation. This study focuses on the emission characteristics of the ionic liquid thruster under varied AC conditions. The AC power supply was set within the frequency range of 0.5–64 Hz, with eight specific frequency conditions selected for experimentation. The experimental results indicate that the thruster operates steadily within a voltage range of ±1470 to ±1920 V, with corresponding positive polarity current ranging from 0.41 to 4.91 μA and negative polarity current ranging from −0.49 to −4.10 μA. During voltage polarity switching, an emission delay occurs, manifested as a prominent peak signal caused by circuit capacitance characteristics and a minor peak signal resulting from liquid droplets. Extended emission test was conducted at 16 Hz, demonstrating approximately 1 h and 50 min of consistent emission before intermittent discharge. These findings underscore the favorable impact of AC conditions within the 8–16 Hz range on the self-neutralization capability of the ionic liquid thruster.

Cyclic compressive behavior of high-performance hybrid fiber reinforced recycled aggregate concrete: Degradation law and acoustic emission features

To tackle the issues of inadequate mechanical properties of recycled aggregate concrete and its limited application in load-bearing structural components, a high-performance hybrid fiber reinforced recycled aggregate concrete (HP-HFRAC) was developed in this study. Sixteen groups of HP-HFRAC specimens fabricated with varying replacement rates of recycled coarse aggregate and different fiber parameters were subjected to uniaxial compression, as well as acoustic emission (AE) tests, to investigate the cyclic behavior and uncover the underlying mechanisms. The findings demonstrated a strong correlation between the AE signals and the macroscopic phenomenon throughout the whole compression process. The AE amplitude distribution was found to be capable of identifying damage mechanisms, including matrix cracking (40–50 dB), fiber sliding (50–80 dB), and fiber pull-out (more than 80 dB). Additionally, the inclusion of hybrid fibers contributed to mitigating the degradation of stiffness and the accumulation of plastic strain, resulting in the ductile failure of the specimens and significantly enhancing the energy dissipation capacity. Specifically, the peak stress of specimens with 1.5% steel fibers increased by 19% compared to that of specimens without steel fibers, compensating for the strength loss due to the presence of recycled coarse aggregate. Finally, constitutive equations governing the skeleton curves and the unloading and reloading curves of HP-HFRAC subjected to cyclic compression were formulated, which were validated using both the test results and the predicted results of the physics-based data-driven model previously published in our companion paper. The findings of this study might contribute to the development of sustainable high performance recycled aggregate concrete for reliable application in load-bearing components.

Coupled slow strain rate and acoustic emission tests for gaseous hydrogen embrittlement assessment of API X65 pipeline steel

Hydrogen embrittlement (HE) sensitivity of API X65 pipeline steel was evaluated in this study through the simultaneous application of slow strain rate tests (SSRT) and acoustic emission (AE) monitoring on hollow dog-bone samples. Exposure to hydrogen gas decreased the elongation to fracture percentage with a significant rise in embrittlement index for the higher pressure of 10 MPa. SEM images of the fracture surfaces demonstrated that the fracture mechanism changed from ductile to ductile–brittle under 1 MPa pressure, and to predominantly brittle with quasi-cleavage characteristic when testing under 10 MPa hydrogen gas. Classification of the AE events based on waveform analysis revealed a mainly shear mode fracture for 10 MPa nitrogen sample, while a dominant tensile mode fracture was identified for the hydrogen charged samples.

Speech services by speech volunteers for children with cleft lip and palate in professional lacking area: Pilot study

Background: Cleft lip and cleft palate are the most common birth defects. Children with cleft lip with or without cleft palate (CP±L) face a vary of challenges, depending on the type and severity of the cleft including speech difficulty, dental problems, feeding difficulty, ear infections and hearing loss. Articulation error is the most common residual defect in children with cleft palate with or without cleft lip. Objective: To compare the numbers of pre- and post- articulation errors after using the Model of Speech Therapy by Volunteers (STV) for children with CP±L. Materials and methods: 9 children, aged range 6; 4-14; 2 years old, were included in this study and completely participated in the study. Pre- and post-articulation tests by Myanmar Articulation, Resonation, Nasal Emission and Nasal Turbulence Test were assessed at Mahamuni Monastery, and Thiriyadana Guha Pone Htoon Shan Monastery, Tachileik, Myanmar. STV is composed of a 3-day speech camp (1st month), 3 times 1-day site visits for complicated cases (2nd, 6th, and 10th months) and 3 times of 1-day follow-up speech camps (4th, 8th, and 12th months), Phonological approaches, traditional strategies, and specific techniques for speech correction in children with CP±L were taught to speech volunteers (SVs) and caregivers. Homework was assigned to SVs and caregivers. SVs provided a session of 45-minute speech correction every week. Caregivers practiced 5 sessions of 30 minutes in speech exercises /weeks at home. Results: STV revealed significant reductions in the numbers of articulation errors including articulation screening test [median difference: MD=6 (95% confident interval: CI=5.2-9.2)], and Myanmar articulation standard test at both word and sentence levels; [MD=8 (95% CI=6.5-10.8) and MD=5 (95% CI=4.2-8.3), respectively]. Conclusion: STV significantly decreased a number of articulation errors in children with CP±L of Myanmar, a professional lacking area, and could be applied in any area that has a similar situation. The result was a primary study, the further research should enroll more participants for generalization.

Mechanical properties and acoustic emission characteristics of soft rock with different water contents under dynamic disturbance

Uniaxial compression tests and cyclic loading acoustic emission tests were conducted on 20%, 40%, 60%, 80%, dry and saturated muddy sandstone by using a creep impact loading system to investigate the mechanical properties and acoustic emission characteristics of soft rocks with different water contents under dynamic disturbance. The mechanical properties and acoustic emission characteristics of muddy sandstones at different water contents were analysed. Results of experimental studies show that water is a key factor in the mechanical properties of rocks, softening them, increasing their porosity, reducing their brittleness and increasing their plasticity. Under uniaxial compression, the macroscopic damage characteristics of the muddy sandstone change from mono-bevel shear damage and ‘X’ type conjugate bevel shear damage to a roadway bottom-drum type damage as the water content increases. Dynamic perturbation has a strengthening effect on the mechanical properties of samples with 60% and less water content, and a weakening effect on samples with 80% and more water content, but the weakening effect is not obvious. Macroscopic damage characteristics of dry samples remain unchanged, water samples from shear damage and tensile–shear composite damage gradually transformed into cleavage damage, until saturation transformation monoclinic shear damage. The evolution of acoustic emission energy and event number is mainly divided into four stages: loading stage (I), dynamic loading stage (II), yield failure stage (III), and post-peak stage (IV), the acoustic emission characteristics of the stages were different for different water contents. The characteristic value of acoustic emission key point frequency gradually decreases, and the damage degree of the specimen increases, corresponding to low water content—high main frequency—low damage and high water content—low main frequency—high damage.

The effect of tympanostomy tubes on otoacoustic emissions.

Otoacoustic emissions (OAE) are a common screening tool to evaluate cochlear function. Middle ear dysfunction has been shown to impact results of otoacoustic emission testing, but there are limited data on the effect of tympanostomy tubes on OAE. The purpose of this study was to determine whether tympanostomy tube placement significantly improved OAE. A retrospective review of charts was completed for patients younger than 18years old who underwent tympanostomy tube placement from January 1, 2018 to September 1, 2023 and had preoperative and postoperative OAE testing within 6months of surgery. The primary variable was presence of OAE preoperatively and postoperatively. Chi-square analysis and t test were used for statistical analysis. A total of 212 ears were examined from 111 pediatric patients who underwent tympanostomy tube placement during the study period. Presence of OAE at 3000, 4000, and 5000Hz were all noted to significantly increase following tympanostomy tube placement, with OAE presence increasing from approximately 27.8% of the sample preoperatively to 95.3% postoperatively at 3000 and 4000Hz. Patients who noted improvement had a significantly higher proportion of type B tympanogram preoperatively, compared to a higher proportion of type A tympanogram noted in patients who did not note improvement. Tympanostomy tubes can significantly improve otoacoustic emissions in patients with middle ear dysfunction.

Study on the Damage Evolution of Weathered Granite under Different Confining Pressure Based on Hoek-Brown Failure Criterion and Acoustic Emission Parameters

Abstract The stability of the mine construction is significantly impacted by weathered granite (WG), which presents a significant risk to the security of workers and equipment. In order to investigate the strength characteristics of WG under different confining pressures, acoustic emission (AE) and scanning electron microscopy (SEM) tests were performed on WG under triaxial compression. The relationship between strength evolution and different confining pressures of WG is studied. Under various confining pressures, the variation regularity of the AE parameters of rock samples was examined. Additionally, the microscopic morphology of rock samples is investigated using SEM. The results show that increased confining pressure suppresses WG damage development before the stress peak and switches to promoting damage development following the stress peak. The axial strength is quantitatively analyzed before the WG stress peak using the Hoek-Brown failure criterion, and the axial damage threshold stress under different confining pressures is obtained. Furthermore, the axial damage threshold stress point is clearly increased in the AE ring count rate and energy rate curves of WG at various confining pressures. The last effect of water on WG is microstructural weakening, which manifests itself in the swelling and erosion of the structure by water.

Analysis of the impact of exhaust gas emissions on diesel fueled vehicles in view from the year of manufacture (Case study on the Mitsubishi L 300 vehicle)

Air pollution is a condition caused by exhaust gas from motor vehicles operating on the highway. To minimize greater air pollution, the government is making preventive efforts by carrying out regular vehicle emission tests which are currently being carried out targeting transport vehicles. This is triggered by the increasing development of the automotive industry so that every year manufacturers produce these vehicles to meet the vehicle market, especially transport vehicle. With the increase in the number of vehicles every year, this is one of the causes of air pollution, so it needs to be controlled. This research aims to determine the effect of vehicle exhaust emissions on the year of vehicle production, in diesel fueled vehicles. The method used is an experiment using two-way Anova analysis on the results of tests carried out on Mitsubhisi L 300 vehicles with a total of 30 test samples, by testing vehicles produced in 2017 - 2022. The results of the research show that older vehicles will produce gas emissions. tall one. This is in accordance with the results of the ANOVA test which accepts the statement that there is at least one vehicle age that has a significant effect on smoke concentration, so it can be concluded that vehicles with an old age, in this case 2017, have the potential to produce high emission gases, therefore preventive efforts need to be taken. to vehicle engines

The Impact of Varying Mixing Rates in a Surfactant-Free Fuel Emulsion Mixer on the Efficiency and Emissions of a Diesel Engine

The research focuses on water diesel emulsion (WDE), a topic that has captivated researchers for an extended period. While previous studies predominantly employed surfactants to enhance mixing efficiency, their non-economic feasibility in transportation logistics has prompted a shift in recent investigations. This study presents experiments utilizing a cost-effective WDE comprising 15% water and a mixer devoid of surfactants to investigate the impact of mixer blade rotation on engine performance, fuel consumption, and NOx emissions. NOx emission tests were conducted under a constant engine speed of 2,000 rpm and a 75% load (3,23 kW). The optimal brake-specific fuel consumption (BSFC) for the 15% WDE fuel occurred at a blade rotation speed of 3,000 rpm, resulting in a 1% power reduction (from 4,41 kW to 4,38 kW), a 13.3% decrease in BSFC (from 694,98 gr/kW.h to 602,52 gr/kW.h), and a 30% reduction in NOx emissions (from 54 ppm to 38 ppm). This discovery holds promise for future advancements in green energy applications within the transportation sector.

Optimized Field Emission from Graphene Sheets with Rare Earth Oxides

This paper demonstrates a simple method to improve the field emission of graphene sheets (GSs) by coating them with thin films of rare earth oxides. The rare earth oxide films are coated on GS using drop coating, without changing the surface morphology, resulting in a remarkable improvement in the field emission properties of GSs. The field emission property of GSs is tunable and can be optimized by applying various rare earth oxide films at the appropriate level. It is found that the turn-on field of GSs is reduced from 4.2 V/mm to 1.7 V/mm by Gd2O3 and to 2.2 V/mm by La2O3. The threshold field of GS is also reduced from 7.8 V/mm to 3.4 V/mm and 4.8 V/mm, respectively. Field emission results indicate that the improvement is due to the low work function surface and more effective emission sites generated around the GS surface after coating. The field emission test and the emission pattern suggest that the field emission performance of GS can be significantly enhanced through the application of La2O3 and Gd2O3 coating, as well as by optimizing the concentration of rare earth oxides in the coating. Hence, the rare earth-coated GS can serve as a potential field emitter.

Comparison of Intratympanic Oxytocin and Dexamethasone in Cisplatin Ototoxicity: An Experimental Study.

Although it is widely used, there is still no valid treatment for ototoxicity caused by the antineoplastic drug cisplatin. In this study, we aimed to investigate the efficacy of intratympanic resveratrol and intratympanic dexamethasone treatment in cisplatin-induced ototoxicity. We also compared intratympanic atosiban (oxytocin antagonist) and oxytocin in cisplatin ototoxicity. In this study, 30 rats (60 ears) were used by separating into 5 groups. Cisplatin, oxytocin, dexamethasone, atosiban and 0.9% NaCl were administered intraperitoneally to all groups separately. Auditory Brainstem Response and Distortion Product Otoacoustic Emission tests were performed on all groups before and 72h after the procedure. Pre-treatment values were higher than post-treatment values in all groups (p < 0.001). There was no significant prolongation of the post-treatment Auditory Brainstem Response I-IV interval in the oxytocin and dexamethasone groups (p > 0.05). There was no significant decrease in the frequencies of 2832 and 4004 after treatment in the oxytocin and dexamethasone group compared to pre-treatment in Distortion Product Otoacoustic Emission. As a result, it has been shown that intratympanic oxytocin may be an option that can be used in the treatment, although it is not as effective as dexamethasone in preventing cisplatin ototoxicity.

Emissions of Gases and Dust into the Air as a Result of the Conversion of Landfill Gas into Electricity and Heat in a Cogeneration Plant

The consequence of landfilling is biogas production in the waste bed, the main parameter of which is methane. The capture of biogas and its energetic use in a cogeneration system is the optimal solution for both environmental and energetic aspects. Nevertheless, the emission of gases and dust into the air from the cogeneration plant as a result of the combustion of biogas poses a potential threat not only to the surrounding ecosystem but also poses a serious risk to human health, especially to the respiratory system, leading to a variety of diseases. The gas and dust emission tests performed in the study showed significant values for CO2 173.08 [kg ∙ h-1] and for CO 0.7545 [kg ∙ h-1], NO2 0.7129 [kg ∙ h-1], SO2 0.3958 [kg ∙ h-1] and total dust 0.0013 [kg ∙ h-1] respectively. The work aims to demonstrate the actual emissions of gases and dust into the air as a result of the combustion of landfill gas and to use them to calculate fees for the use of the environment. Since no emission standards have been defined for this type of installation and there is no need to use reducing devices, it is crucial to regularly monitor pollutant emissions by installation operators to optimize the biogas combustion process and reduce emissions. Replacing the reference values with measurement data regarding air emissions will make the actual impact of the cogeneration installation on the environment more realistic.

Experimental investigation of physical and tensile mechanical properties of granite after different heating and cooling treatments

In this study a series of physical properties of granite were tested after different cooling treatments. Correspondingly, Brazilian splitting testing combined with acoustic emission (AE) testing was conducted on five groups of granite samples at different temperature levels, and scanning electron microscopy (SEM) was used to investigate the microstructure of granite. It was found that the P-wave velocity, hardness and thermal conductivity decreased with rising temperature. The tensile strength of granite was deteriorated by the action of temperature, and the progression of cracks was monitored using AE technology. The SEM results also indicated a significant increase in both the number and density of cracks in granite samples subjected to temperature variations compared to a naturally cooled group. In addition, after heating and cooling at different temperatures, samples with lower tensile strength exhibited rougher fracture surfaces, which were attributed to the generation of more thermal cracks during the heating and cooling processes. Moreover, a variation in the mechanisms for granite after temperature treatment is proposed.

Experimental study of the effects of fracture number on the creep and acoustic emission characteristics of sandstone

Creep and acoustic emission tests were conducted under uniaxial compression on sandstone samples with no (i.e. intact), one and two prefabricated fractures collected from the Xiaolangdi Reservoir area using a RLJW-2000 rock microcomputer-controlled rheology servotest system and PCI-2 acoustic emission testing equipment, respectively. The change laws of the acoustic emission amplitudes, peak frequencies, acoustic emission events and b values of samples with different fracture numbers (i.e. number of fractures) were systematically analysed. The differences between the prediction made by acoustic emission b values and cumulative ringing count for the precursor time of creep failure in a rock mass were studied comparatively, thereby identifying the effects of fracture number on the creep and acoustic emission characteristics of sandstone. According to the study results: (1) With an increase in the prefabricated fracture number, the acoustic emission signal counts of samples increased within the amplitude intervals of 60–80 and 80–100 dB. The signal counts were especially high in the high-amplitude interval of 80–100 dB but they decreased within the low-amplitude interval of 45–60 dB. (2) Under each stress level, the total acoustic emission event counts generated by the single- and double-fracture samples were 1.90 and 2.36 times that generated by the intact sample, respectively. Under the last stress level, the event counts generated by the single- and double-fracture samples were 4.64 and 6.19 times the event count generated by the intact sample, respectively. A higher prefabricated fracture number implied higher total acoustic emission event counts generated by samples and higher acoustic emission event counts generated under the last stress level. (3) Under the same stress level, the frequency band concentration of acoustic emission signals of samples became more pronounced as the prefabricated fracture number increased. Under the last stress level, as the prefabricated fracture number increased, the peak frequencies of the acoustic emission signals of samples were concentrated in a greater number of frequency ranges (four, seven and eight frequency ranges, respectively). (4) With an increase in the prefabricated fracture number, the average acoustic emission b values of samples presented an overall declining trend, with an increased Δ b range. (5) The plunge rates of acoustic emission b values of the single- and double-fracture samples before accelerated creep failure increased by 8.0 and 11.2%, respectively, compared with the intact sample. (6) The acoustic emission b value curves and cumulative ringing count curves for samples with different fracture numbers predicted creep failure in the rock mass earlier than the strain curves. For all samples, the precursor time points of creep failure in the rock mass predicted by acoustic emission b value curves were all earlier than those predicted by corresponding cumulative ringing count curves. As the prefabricated fracture number increased, the precursor time points of creep failure in the rock mass predicted by acoustic emission b value curves occurred even earlier. Thematic collection: This article is part of the Engineering Geology and Hydrogeology of the Anthropocene collection available at: https://www.lyellcollection.org/topic/collections/engineering-geology-and-hydrogeology-of-the-anthropocene

Properties of substitute motor fuels produced from ethanol in biorefineries

The article presents the definition of bioindustry, in particular biorefinery. The technology for obtaining synthetic fuel EtG (Ethanol to Gasoline) in a plant using bioethanol from food waste was presented. The physicochemical properties of EtG fuel were presented. EtG fuel stands out due to its limited content of benzene and sulfur and a low content of mechanical impurities and heavy metals. EtG fuel can be considered a replacement fuel for motor gasoline. The results of exhaust emissions tests from vehicles with spark-ignition engines in the WLTC test on a hot and cold engine were presented. It was found that EtG fuel is characterized by lower specific distance emissions of CO, NOx and CH4 and slightly higher specific distance emissions of NMHC when starting a cold engine compared to gasoline, while the specific distance emission of CO2 for both fuels were very similar.

Variasi aktivator H2SO4 dan NaOH untuk pemurnian oli bekas dan emisi pengujian gas buang yang dihasilkan

Oil consumption has increased every year in line with the increase in used oil produced. Used oil is included in the waste of Hazardous and Toxic Materials which have a bad impact on the environment. One of the technologies that can be utilized in processing used oil is refining because used oil contains base oil so that it can be reused as fuel. This study aimed to determine the best variation of using H2SO4 and NaOH in refining used oil, then the characteristics of the refined used fuel oil are tested for density, specific gravity, calorific value, viscosity, and moisture content, as well as exhaust emissions produced. The research method used was the acid and clay method with variations of H2SO4 and NaOH with the same values of 4% (P4), 5% (P5), and 6% (P6). The results showed that P6 type fuel is the best variation that comes closest to the diesel quality standard according to the Decree of the Directorate General of Oil and Gas 146 K/10/DJM/2020. In addition, the resulting emission also has the lowest value compared to the other two variations. The density values obtained were 857 kg/m3, a specific gravity of 0.857, a heating value of 47465 kJ/kg, a viscosity of 1.24 mm2/s, and a water content of 43.887 mg/kg. Meanwhile, in the exhaust emission testing, CO emissions were 0.030%, CO2 was 4.590%, HC was 19.50 ppm, and ƛ was 2.75.

Study on the evolution of limestone damage and permeability under the tunnel driving stress path

The tunnel water inrush problems threaten the safety of tunneling. To understand the water inrush mechanism in tunnel tunneling, triaxial water seepage test and COMSOL numerical simulation were applied to study the water seepage law of tunnel surrounding rock according to the tunnel driving stress path. The results show that the permeability changes slowly, increases sharply and decreases sharply, respectively, during seepage and mechanical loading-unloading. However, during the σ1−σ3 active unloading stage, the permeability cannot return to the state before the plastic stage. The permeability presents a highly fitting exponential relationship with the stress of deviatoric and effective volume. During different loading and unloading stages, the index relationship is different, which is related to the rock damage degree. Through uniaxial cyclic loading-unloading acoustic emission test, it is verified that axial strain ε1 is related to cumulative AE count, that is rock damage degree. The damage variable D based on axial strain ε1 was established, and the permeability evolution law was effectively characterized by damage variable D. The permeability and crack evolution process cannot be directly observed during seepage test. The numerical model of real heterogeneous rock samples is established based on COMSOL. The simulated rock shear fracture feature is close to that of laboratory tests. In the numerical simulation of seepage, the evolution laws of damage, fracture and permeability in rock are effectively quantified. It is proved that the necessary numerical simulation can serve as an effective supplement to the laboratory test.