Effects Of Deterioration Research Articles

Leading role of natural resources, eco-efficiency assessment, and energy transition in environmental sustainability: A depth of digital transformation

There has been a worldwide upsurge in environmental movements. The planet's ecosystem has degraded significantly over the years. The disturbing effects of environmental deterioration on Earth's physical geography cause concern among those concerned about the planet's future. While previous research has looked at various ecological elements, recent attention has turned to digital change and the need to make the most of it. Eco-efficiency is a critical component in reducing carbon output (CO2). Reaching carbon neutrality goals, getting carbon peaking, and achieving high-quality economic growth, digital transformation, and eco-efficiency are intense endeavors. A panel data set spanning G-15 economies from 1995 to 2022, this article examines the effects of digital transformation, eco-efficiency, and the food supply chain on carbon emissions. The unit root test established the stationarity of all indicators at the initial difference. In addition to Pedroni and Kao cointegration methods, the panel study uses ADF, DF-GLS, and PP unit root test, as well as dynamic ordinary least square (DOLS) and fully FMOLS stands for panel adjusted regular least square. Approaches for robustness: the present research additionally uses panel quantile regression to examine the effect of factors. In order to promote environmental sustainability and minimize CO₂ emissions, the findings highlighted the need for eco-efficiency, digital transformation, the food supply chain, and government policy. On the other hand, natural resource exploitation and energy transition worsen environmental quality and raise CO2 emissions in Great economies. We use the DH panel causality test to assess the factors' correlation further. Furthermore, carbon emissions (CO2) are affected in one way by changes in the energy sector and the food supply chain and in another by changes in eco-efficiency, digital transformation, and government policy. Environmental deterioration has many causes, and this study's results may help shed light on those reasons while suggesting solutions.

Acoustic emission characteristics and damage constitutive model of high-performance concrete of freezing shaft under hydro-mechanical coupling

To examine the fracture development and damage characteristics of concrete subjected to high-bearing-pressure water in deep water-rich formations, a rock triaxial testing machine combined with an acoustic emission system was utilized to carry out the acoustic emission characterization test of high-performance concrete under hydro-force coupling conditions. The crack development and failure patterns of concrete were analyzed using an improved bi-value and Gaussian mixture model. In addition, a concrete damage model that incorporated the hydrodynamic deterioration effect and post-peak residual strength was developed. The results indicated a three-stage evolution of the bi-value throughout the stress-strain process: initial increase, subsequent fluctuating variation with a tendency to decrease, and eventual plunge. This pattern effectively captured the internal crack development in concrete. During the compression process coupled with hydraulic force, the concrete formed tension-shear composite cracks, predominantly comprising tension cracks. The proportion of shear cracks decreased as the initial water pressure increased. The influence of high-pressure water on the shear strength of concrete was mainly reflected in the weakening effect of cohesive force. By substituting the experimental strain data into the established intrinsic model for verification, the correlation coefficients were all greater than 0.96, more accurately simulating the influence of hydraulic pressure and the strain softening phenomenon caused by the peripheral pressure. The research results provide a scientific basis for understanding the concrete damage mechanism and for preventing and controlling the structural damage in concrete shaft linings.

An Engine Deterioration Model for Predicting Fuel Consumption Impact in a Regional Aircraft

A deterioration cycle model is presented, designed to consider the turbomachinery efficiency losses that are expected during real engine in-service operations. The cycle model was developed using information from practical experience found in the literature to account for both short- and long-term deterioration effects; the former occurring during the first flight cycles, the latter due to regular in-service operation. This paper highlights the importance of analyzing the inter-turbine temperature margin (ITTM) to track engine deterioration to determine the extent of an in-service engine life. The proposed model was used to assess the ITTM and fuel consumption impact in the CRJ-700 regional aircraft (powered by two CF34-8C5B1 engines) for three representative missions: short (0.4 h), average (1.4 h), and long (2.5 h), considering different levels of engine deterioration, from the new engine level up to fully deteriorated. The fuel consumption at the new engine level (zero deterioration) was validated against a real-time engine model embedded in a Level-D flight simulator, the so-called Virtual Research Flight Simulator located at the Laboratory of Applied Research in Active Control, Avionics, and AeroServoElasticity. The errors found in this validation for the trip mission fuel consumption in the short, average, and long missions were −3.6, +0.9, and +0.6%, respectively. The cycle model predictions suggest the ITTM for a new engine is 55.2 °C, whereas for a fully deteriorated engine, it is 26.4 °C. Finally, in terms of fuel consumption, the results presented here show that an average CF34-8C5B1 engine shows an increase in the cumulative fuel consumption of 2.25% during its life in service, which translates to a 4.5% impact in aircraft fuel consumption.

An Experimental Investigation of the Mechanism of Hygrothermal Aging and Low-Velocity Impact Performance of Resin Matrix Composites.

Resin matrix composites (RCs) have better thermal and chemical stability, so they are widely used in engineering fields. In this study, the aging process and mechanism of two different types of resin-based three-dimensional four-way braided composites (H15 and S15) under different hygrothermal aging conditions were studied. The effect of aging behavior on the mechanical properties of RCs was also studied. Three different aging conditions were studied: Case I, 40 °C Soak; Case II, 70 °C Soak; and Case III, 70 °C-85% relative humidity (RH). It was found that the hygroscopic behavior of RCs in the process of moisture-heat aging conforms to Fick's second law. Higher temperatures and humidity lead to higher water absorption. The equilibrium hygroscopic content of H15 was 1.46% (Case II), and that of S15 was 2.51% (Case II). FT-IR revealed the different hygroscopic mechanisms of H15 and S15 in terms of aging behavior. On the whole, the infiltration behavior of water molecules is mainly exhibited in the process of wet and thermal aging. At the same time, the effect of the aging process on resin matrices was observed using SEM. It was found that the aging process led to the formation of microchannels on the substrate surface of S15, and the formation of these channels was the main reason for the better moisture absorption and lower mechanical strength of S15. At the same time, this study further found that temperature and oxygen content are the core influences on post-aging strength. The LVI experiment also showed that the structural changes and deterioration effects occurring after aging reduced the strength of the studied material.

Chronic kidney disease activates the HDAC6-inflammatory axis in the heart and contributes to myocardial remodeling in mice: inhibition of HDAC6 alleviates chronic kidney disease-induced myocardial remodeling.

Chronic kidney disease (CKD) adversely affects the heart. The underlying mechanism and the interplay between the kidney and the heart are still obscure. We examined the cardiac effect using the unilateral ureteral obstruction (UUO)-induced CKD pre-clinical model in mice. Echocardiography, histopathology of the heart, myocardial mRNA expression of ANP and BNP, the extent of fibrotic (TGF-β, α-SMA, and collagen I) and epigenetic (histone deacetylases, namely HDAC3, HDAC4, and HDAC6) proteins, and myocardial inflammatory response were assessed. Six weeks of post-UUO surgery, we observed a compromised left-ventricular wall thickness and signs of cardiac hypertrophy, accumulation of fibrosis associated, and inflammatory proteins in the heart. In addition, we observed a perturbation of epigenetic proteins, especially HDAC3, HDAC4, and HDAC6, in the heart. Pharmacological inhibition of HDAC6 using ricolinostat (RIC) lessened cardiac damage and improved left-ventricular wall thickness. The RIC treatment substantially restored the serum cardiac injury markers, namely creatine kinase-MB and lactate dehydrogenase (LDH) activities, ANP and BNP mRNA expression, and heart histological changes. The extent of myocardial fibrotic proteins, phospho-NF-κB (p65), and pro-inflammatory cytokines (TNF-α, IL-18, and IL-1β) were significantly decreased in the RIC treatment group. Further findings revealed the CKD-induced infiltration of CD3, CD8a, CD11c, and F4/80 positive inflammatory cells in the heart. Treatment with RIC substantially reduced the myocardial infiltration of these inflammatory cells. From these findings, we believe that CKD-induced myocardial HDAC6 perturbation has a deteriorative effect on the heart, and inhibition of HDAC6 can be a promising approach to alleviate CKD-induced myocardial remodeling.

How does carbonation of alkali-activated slag and Portland cement systems impact steel corrosion differently?

Carbonation of cementitious materials, associated with neutralization of pore solution, is one of the prevalent reasons for inducing corrosion of steel in concrete. Compared with ordinary Portland cement (OPC) concrete, the poorer carbonation resistance of alkali-activated slag (AAS) concrete leads to serious durability concerns of a higher risk of steel corrosion. This work investigates the corrosion behaviors of steel embedded in intact and carbonated AAS and OPC mortars exposed to various relative humidity conditions, with the aim of fostering a better understanding of how carbonation impacts steel corrosion differently in these two cementitious systems. The results show that uncarbonated AAS mortars have better protective ability against corrosion than OPC counterparts; however, poorer performance after complete carbonation. It is mainly attributed to the combined effect of severe deterioration and coarsening of pore structure and increased ratio of chloride ion concentration to hydroxide ion concentration ([Cl−]/[OH−]) in pore solution, resulted from the consumption of hydroxide ions and release of bound chloride after carbonation. Besides, the different shifts of R-C (material resistivity versus corrosion rate) relationship lines in AAS and OPC mortars after carbonation are observed, which is ascribed to the different compositional and microstructural evolutions induced by carbonation in these two cementitious systems.

Investigation of freeze–thaw deterioration effects on electrical properties and electric-heating capability of CNT-CF incorporated cement mortar

Investigation of freeze–thaw deterioration effects on electrical properties and electric-heating capability of CNT-CF incorporated cement mortar

Numerical study on heat transfer characteristics of regenerator based on a simplified geometry

The heat transfer characteristics of regenerator in regenerative coolers such as pulse tube and Stirling coolers is important. Various methodologies of characterizing the Nusselt number between the regenerator matrix and working fluid have been established and applied. However, most of the existing formulas are based on the study of steady flow or oscillating flow with low pressure ratios at above ambient temperature. In this paper, a tube model with finite wall thickness was constructed to numerically simulate simplified #400 SS mesh and packed HoCu2 sphere, with the aim of investigating the Nusselt number in regenerators under various flow conditions, including different Valensi numbers and temperature ranges. The results provide more evidence to support that within the operating conditions, including Valensi numbers and pressure ratios typically used in coolers, the Nusselt number of oscillating flow and steady flow are similar. Additionally, a heat transfer deterioration effect is observed below 40 K, which is related to the heat capacity ratio between the solid matrix and working fluid. Based on these findings, the study emphasizes the importance of further investigating the heat transfer characteristics of oscillating flow at low temperatures.

Experimental study on the deterioration of mechanical properties of sandy mudstone under different water-gas interactions

Based on the water-rock-gas coupling test system, the work combined the scanning electron microscope and XTDIC 3D full-field strain measurement system. The Brazilian splitting test was performed on four groups of sandy mudstone specimens under contrast (CO), mash-gas soaking (MS), water-mash gas soaking (WM), and water-soaking (WS) conditions. The tensile strength, deformation failure, and microscopic characteristics of fractures were studied to reveal the deterioration mechanism of the tensile properties of sandy mudstone under water-gas coupling. The results showed that the uniaxial tensile strength of sandy mudstone specimens under the three soaking conditions was less than that of the contrast conditions. Compared with specimens in the CO group, the tensile strength of specimens in MS-WS groups was reduced; the WS group decreased the most. Specimens changed from brittle failure to plastic failure after soaking. The decrease rate in strength after the peak was consistent with the change trend in tensile strength. It led to a larger localized deformation zone of specimens and more obvious displacement. The deformation localization zone of the WS group was the broadest, with the most intense displacement. Besides, stress concentration first occurred in the submerged part of the WM group. Fractures expanded in the direction of maximum principal strain. The internal pore structure of sandy mudstone specimens in each group changed after soaking. The average porosity, maximum pore area, and probability entropy of specimens in WS-MS groups increased compared to the CO group. The WS group had the largest reduction and the MS group had the smallest. The pre-peak energy storage capacity of sandy mudstone specimens was gradually weakened. Compared with the CO group, that in the WS-MS groups was reduced. The WS group had the greatest reduction, and the MS group had the smallest. The deterioration effect of water on the interior of sandy mudstone was stronger than that of gas. The work is of great significance for understanding the stability of coal and rocks in closed-pit high-gas mines.

Impact of the water-wedge deterioration effect of pulsating water injection on AE waveforms and crack propagation during fracturing processes

Pulsating hydraulic fracturing (PHF) is a promising technology for enhancing the extraction of coalbed methane. In this study, the effects of pulsating water response of coal fractures were investigated. Prior to quasi-static fracturing, coal samples were subjected to pulsating water injection for 120 min. The fracturing process was monitored using an acoustic emission (AE) system and compared with direct fracturing without pulsating water injection. The Hilbert–Huang transform theory was employed for the analysis. The AE signals were examined in time and frequency domains, across various parameters, including intrinsic mode function (IMF) components, energy, three-dimensional spectrum, location features, and crack development. The results indicated a 37.82 % reduction in initiation pressure, accompanied by decreased AE counts and the promotion of gradual fracture initiation. Initially, the AE waveform amplitudes decreased, followed by an increase in distinctive patterns. Water injection primarily reduced the amplitudes during unstable fracturing, shifting the extreme IMF component forward. Moreover, it decreased the peak energy, shortened the energy release duration, and improved the signal-to-noise ratio during crack propagation. Water injection also narrowed the frequency distribution range, concentrated the energy distribution, expanded the extent of the fracture, increased the number of location points, and induced more macroscopic cracks within the coal body.

Microbial consortium with multifunctional attributes for the plant growth of eggplant (Solanum melongena L.).

In the past few decades, the pressure of higher food production to satisfy the demand of ever rising population has inevitably increased the use synthetic agrochemicals which have deterioration effects. Biostimulants containing beneficial microbes (single inoculants and microbial consortium) were found as an ideal substitute of synthetic chemical fertilizers. In recent years, microbial consortium is known as a better bioinoculant in comparison to single inoculant bioformulation because of multifarious plant growth-promoting advantages. Looking at the advantageous effect of consortium, in present investigation, different bacteria were isolated from rhizospheric soil and plant samples collected from the Himalayan mountains on the green slopes of the Shivaliks, Himachal Pradesh. The isolated bacteria were screened for nitrogen (N) fixation, phosphorus (P)solubilization and potassium (K) solubilization plant growth promotingattributes, and efficient strains were identified through 16S rRNA gene sequencingand BLASTn analysis. The bacteria showing a positive effect in NPK uptake were developed as bacterial consortium for the growth promotion of eggplant crop. A total of 188 rhizospheric and endophytic bacteria were sorted out, among which 13 were exhibiting nitrogenase activity, whereas 43 and 31 were exhibiting P and K solubilization traits, respectively. The selected three efficient and potential bacterial strains were identified using 16S rRNA gene sequencing as Enterobacter ludwigii EU-BEN-22 (N-fixer; 35.68 ± 00.9 nmol C2H4 per mg protein per h), Micrococcus indicus EU-BRP-6 (P-solubilizer; 201 ± 0.004 mg/L), and Pseudomonas gessardii EU-BRK-55 (K-solubilizer; 51.3 ± 1.7 mg/mL), and they were used to develop a bacterial consortium. The bacterial consortium evaluation on eggplant resulted in the improvement of growth (root/shoot length and biomass) and physiological parameters (chlorophyll, carotenoids, total soluble sugar, and phenolic content) of the plants with respect to single culture inoculation, chemical fertilizer, and untreated control. A bacterial consortium having potential to promote plant growth could be used as bioinoculant for horticulture crops growing in hilly regions.

Systematicity of receiving mental health care predicts better subjective well-being of Ukrainians during the second year of the Russian invasion

PurposeThis study aims to develop and test a multivariable psychosocial prediction model of subjective well-being in Ukrainian adults (n = 1,248) 1.5 years after the 2022 Russian invasion of Ukraine.Design/methodology/approachThe research design followed the “Transparent reporting of a multivariable prediction model for individual prognosis or diagnosis” checklist. The online survey combined a questionnaire on sociodemographic characteristics and specifics of living in wartime, as well as validated self-reported inventories: The Modified BBC Subjective Well-being Scale, Acceptance and Action Questionnaire – Version 2 and Connor–Davidson Resilience Scale-10.FindingsThe initially developed model was tested through regression analysis, which revealed nine variables as predictors of the subjective well-being scores within the sample, explaining 49.3% of its variance. Among them, the strongest were living with a friend and receiving mental health care systematically. They were almost twice as influential as forced displacement abroad and trauma exposure, which predicted lower well-being, and living with a spouse, which forecasted higher well-being scores. Two resilience subscales – adjustment and restoring and resistance – as predictors of better well-being and perceived unsuccess in life and age as predictors of lower well-being were relatively weaker but statistically significant.Originality/valueThe obtained results support the previous evidence on the essential role of accessible mental health services and social support in times of war, as well as the deteriorative effect of trauma exposure and forcible taking refuge on subjective well-being.

Effects of biogenic sulfuric acid on simulated concrete septic tanks

Concrete is the major construction material for infrastructure development. Concrete sewer septic tanks are Constructed using the conventional ordinary portland cement (OPC) and the Portland pozzolana cement (PPC). However, OPC based concrete sewer systems are susceptible to biological, mechanical, and chemical degradation. Degradation of the concrete septic leads to their failure hence imposing tremendous environmental problems. The aftermath is the emergence of sanitation-related diseases. The wastewater from failing septic systems leads to contamination of the groundwater or the surface water resulting in the pollution of drinking water. Therefore, the need to explore other possibilities and potential construction materials to achieve sustainable sanitation is inevitable. The use of Limestone Calcined Clay Cement (LC3) in the construction of degradation-resistant concrete sewer septic systems has not been well explored in Kenya. LC3 concrete is resistant to the deterioration effects of aggressive media such as acids, chlorides, and sulfates. This paper presents experimental performance and findings of LC3 in aggressive media vis a vis OPC. The LC3 was formulated by mixing clinker, Calcined clay, limestone, and gypsum at percentages of 50 %, 30 %, 15 %, and 5 % respectively. Compressive strength, Sorptivity, and weight loss during the wet and dry cycles for both LC3 and OPC were evaluated. Simulated concrete septic tanks made of LC3 and OPC were made by casting cubes at water cement ratio of 0.5 and cured in fresh water at ambient temperature for 28 days. These cubes were passed through a regime of W-D cycles in the 3% concentration of Biogenic sulfuric acid. It was observed that after 28 days of curing OPC cubes had slightly higher compressive strength than LC3. However LC3 concrete cubes are expected to have higher compressive strength than the OPC. Cubes curing time increases due to increased pozzolanic activity. Biogenic sulphuric acid attacks on hydrated cement products cause a decrease in compressive strength. The water absorption profile of LC3 cubes was lower as compared to OPC cubes. In conclusion, LC3 cubes had a high potential of resisting degradation as compared to OPC cubes. LC3 show more impressive performance, hence LC3 It’s a potential binder for use in the construction of sewer system.
 Keywords: Septic tank, Sorptivity, compressive strength, wet-dry cycles, biological, mechanical, and chemical degradation, sustainable sanitation, LC3.

A discrete artificial bee colony algorithm and its application in flexible flow shop scheduling with assembly and machine deterioration effect

In real production, assembly and machine deterioration are extremely common phenomenon and flexible flow shop scheduling problem (FFSP) is also extensively investigated. However, assembly FFSP with machine deterioration effect (AFFSP-DE) is neglected. This paper addresses an AFFSP-DE with makespan criterion and proposes a discrete artificial bee colony (DABC) algorithm. In DABC, the number of employed (onlooker) bees is dynamically changeable according to evolutionary quality to adaptively allocate computing resources for two kinds of bees, and a new scout bee phase is designed to improve convergence speed. Finally, the relationships between makespan and different deterioration rates are analyzed systematically by extensive experiments, and the results demonstrate that DABC outperforms the existing algorithms over 82% test instances in solving the AFFSP-DE.

An energy-efficient unrelated parallel machine scheduling problem with learning effect of operators and deterioration of jobs

An energy-efficient unrelated parallel machine scheduling problem with learning effect of operators and deterioration of jobs

Seismic time-dependent resilience assessment of aging highway bridges incorporating the effect of retrofitting

Bridges are one of the most critical components of transportation networks, which are highly vulnerable due to exposure to natural hazards. In addition, multiple degradation mechanisms can considerably affect the functionality of highway bridges during their service life. Therefore, accumulated damage could also arise continuously because of seismic loading and structural deterioration, which consequently can change system resilience over its life-cycle. This study presents a probabilistic methodology to systematically evaluate and develop the time-dependent seismic resilience curves for Reinforced Concrete (RC) bridges under chloride attacks. In this regard, different jacketing materials with varying thicknesses are chosen for retrofitting purposes. In each case, the time-dependent seismic fragility curves (four damage states) for calculating the time-dependent seismic resilience curves are established through Probabilistic Seismic Demand Models (PSDMs) by performing Incremental Dynamic Analysis (IDA). Finally, the time-dependent seismic resilience curves are evaluated based on the time-dependent seismic fragility curves using the restoration function for all the retrofitting strategies by considering the effect of structural deterioration over time. The results indicate that aging, earthquake intensities, and retrofitting strategies undeniably affect the time-variant seismic resilience of bridges, which is helpful for the long-term safety and reliability of bridges.

The influence of aeolian sand on the mechanical properties of cement stabilized crushed stone

The utilization of aeolian sand resources for road construction is a specific measure to develop green and low-carbon transportation, and also conforms to the concept of green and sustainable development of roads in China. Based on this, the feasibility of using aeolian sand as a substitute for fine aggregate for cement stabilized graded crushed stone was explored, and the effects of different aeolian sand dosages on the unconfined compressive strength, bending and flexural strength, and splitting strength of cement stabilized crushed stone mixtures were studied. The results indicate that the addition of aeolian sand has a significant deterioration effect on the mechanical properties of cement stabilized graded crushed stone mixtures. The larger the amount of aeolian sand added, the more severe its impact on the mixture. Therefore, controlling the amount of aeolian sand within 6 % can meet the mechanical performance requirements. To ensure the large-scale utilization of aeolian sand resources, future research can comprehensively consider the shrinkage characteristics, durability, and water stability of cement stabilized crushed stone mixtures, and further recommend the maximum dosage of aeolian sand.

A simply prepared amine oxide molecule as a low work function cathode modifier in organic photovoltaics for harvesting ambient light

Organic photovoltaics (OPV) that possibly convert ambient lights to electric energy are under the spotlight as a power supplier for portable, wearable, and Internet of Things devices. In order to enable the commercialization of ambient light harvesters, it is imperative to design and synthesize device components that offer cost-effectiveness, uniform deposition, and efficient charge extraction/collection. Here, we introduce a simple cathode interlayer (CIL) named EtNO for OPV-based ambient light harvesters. EtNO is designed with a chemical structure that does not require complicated conjugated units and is synthesized through a one-step procedure. EtNO CIL shows efficient reductions in the work function of electrodes, attributed to an interfacial dipole induced from an interaction between amine oxide group of EtNO and electrodes. Furthermore, EtNO forms a uniform layer through solution-processing without deteriorative effects on the surface of photoactive layer in OPVs. Therefore, the OPV with EtNO CIL exhibits an improved performance with an output power density of 79.2 μW cm–2 under light emitting diode illumination (1000 lx, 254 μW cm–2) compared to the device with conventional PDINO CIL (73.1 μW cm–2). Studies conducted on OPVs under halogen light illumination and on large-area devices further demonstrate the significant potential of EtNO as a CIL.

Deterioration modes, mechanisms, and effects of flexible landfill facilities disposing hazardous waste

Dynamic performance and lifespan predictions are essential for understanding the whole life-cycle emissions and environmental impacts of landfills. However, there are knowledge gaps regarding the major failure modes and mechanisms in flexible hazardous waste landfills (FHWLs) and their potential effects on the service life of landfills. These issues limit the advancement of related research. In this study, focusing on flexible landfills, failure mode, mechanism, and effects analysis was conducted to identify the major failure modes, mechanisms, and impacts that may occur in landfills under extremely harsh chemical and stress conditions. The results indicate that there are approximately 33 major components and materials in landfills, corresponding to 35 potential failure modes and more than 60 underlying failure mechanisms. Notably, the failure of the drainage media in the drainage system is concerning and challenging to recover from. In contrast, the failure of the high-density polyethylene geomembrane (HDPE GMB) in the liner system (LS) is considered serious and is prone to occur, but it is also difficult to detect. Therefore, these two failure modes were identified as critical factors affecting the degradation of the performance and longevity of FHWLs. Finally, due to their high probability of occurrence and severe impacts, stress damage (physical damage) and oxidative aging were identified as the main degradation modes of HDPE GMB, the core material in FHWLs. This study provides key insights into performance prediction targets, failure modes, and failure mechanisms for further research on long-term landfill performance and life prediction. It prompts the government and stakeholders to re-examine the rationality behind the positioning of landfills, such as the assumptions of unlimited service and solid waste management endpoints. Therefore, it calls for a reassessment and optimization of the full life cycle emissions of landfills and related waste.

Micro-cracking morphology and dynamic fracturing mechanism of natural brittle sandstone containing layer structure under compression

The failure and instability of sedimentary rocks are related to internal weak surface and potential damage. To explore the influence of layer structure on the crack expansion law and deformation characteristics of sandstone, this study investigated the effect of layer structure on apparent crack degree, microscopic damage law, acoustic emission and deformation field under uniaxial compression. The fracture modes include tensile fracture Ⅰ, tensile fracture Ⅱ, shear fracture and composite fracture with an anisotropic characteristics. The apparent crack degree and stress show a simultaneous evolution feature and the sandstone with significant layer deterioration effect have greater damage degree. The peak stress and elastic modulus have nonlinear exponential relation with layer angles. The acoustic emission (AE) behavior has a phased response to the aging fracture, and AE energy warning points and AE b-value dropping abruptly generally occur near the continuous stress drops or peak stress. The deformation field reveals the principal strain and resultant displacement has a spatiotemporal response characteristic and there is a typical damage competition relationship in the deformation concentration area. The fracturing effect intensifies the dissimilation behavior of deformation field, formation of strain concentration zone and banded dissimilation zones indicate the cracks penetration. The displacement field at the fracture tip shows a significant suddenness and strain concentration region is often pregnant with high-level displacement. These findings on the dynamic fracture mechanism are helpful in the deterioration characteristics of sedimentary rock in underground space engineering.