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Triaxial compression tests were conducted on frozen sandy soils under a constant minimum principal stress (σ3 = 1.6 MPa) and various intermediate principal stresses (σ2 = 1.6, 3.4, 5.2, 7.0, 8.8, 9.8 MPa). The purpose of the research was to investigate the influence of intermediate principal stress on mechanical properties of frozen soil, and to establish a constitutive model to predict the stress-strain relationship of frozen soil under complex stress state. The test results obtained demonstrated that the crack damage stress and failure stress initially increase and then decrease with an increase in the intermediate principal stress. However, the crack initiation stress exhibits an initial increase up to a specific value, after which it stabilizes. From the perspective of crack propagation, the influence mechanism of intermediate principal stress on the strength was discussed. With the variation of stress state, the difference between intermediate principal strain and minimum principal strain gradually increases. The deformation difference was revealed using the stress superposition principle and Poisson's effect. Finally, the constitutive model based on the Weibull distribution and Drucker-Prager strength criterion can accurately represent the stress-strain relationships of frozen sandy soils under true triaxial stress states.

Allergic respiratory diseases can increase serum carcinoembryonic antigen levels. We report three cases experiencing allergic symptoms that proved refractory to inhaled corticosteroids but exhibited a positive response to long-term treatment with oral corticosteroids. This response was characterized by a synchronous alteration in serum eosinophil counts and carcinoembryonic antigen levels. Immunofluorescence assays indicated localized carcinoembryonic antigen production within eosinophils. In addition, we conducted a systematic review of patients exhibiting similar characteristics on PubMed. After comprehensively reviewing this unique pathophysiological condition, we herein introduced a novel term “Allergic hyper-carcinoembryonic antigen syndrome,” defined by the following criteria: (1) recurrent asthmatic attacks; (2) eosinophilia or pulmonary eosinophilic infiltrations accompanied by elevated serum carcinoembryonic antigen levels; (3) pulmonary lesions determined by imaging or biopsy; (4) exclusion of malignancy and infections; and (5) responsive to systemic corticosteroids. Allergic hyper-carcinoembryonic antigen syndrome suggests systemic corticosteroids should be introduced early when managing allergic patients with both eosinophilia and elevated serum carcinoembryonic antigen levels.

In this work, a four-port directional filter (DF) with a broad passband and low reflection is proposed at the W-band, which comprises three unit filters at 92, 95, and 97 GHz, cascaded in series. Each unit consists of two microstrip lines in the top circuit layer for signal input and output, two pairs of apertures in the middle ground layer for directional coupling, and one square loop in the bottom layer as a selective resonator. By sweeping the working frequencies of the three units and optimizing the phase delays between them, the proposed filter achieves a 3-dB bandwidth as broad as 16%, an insertion loss of 2.5 dB at 95 GHz, and an out-of-band rejection of −28 and −23 dB at 80 and 110 GHz, respectively. The corresponding reflection attenuation is larger than 9.6 dB from 60 to 105 GHz. To verify our design, a prototype is fabricated and characterized, and its experimental data are consistent with the simulation. This work significantly expands the bandwidth of DFs and may find many applications in frequency division multiplexing and high-gain wireless systems.

Silicon suboxide (SiOx) is one of the most attractive candidates for anode materials for high-energy-density lithium-ion batteries due to its high specific capacity and its relatively lower volume expansion than that of Si. However, its low initial Coulombic efficiency (ICE) seriously affects its practical applications. In this work, we demonstrate a scalable and effective strategy to enable a high ICE of the SiOx electrode through a MnO-assisted disproportionation reaction. The obtained Mn2SiO4–Si–SiOx@C (MSS@C) material shows a reduced lithium irreversible consumption in the first cycle. The Mn2SiO4 phase can store lithium through a conversion reaction with a smaller volume change (33%) than SiOx, which helps to maintain the structural stability of MSS@C during cycling. Meanwhile, the metallic Mn nanoparticles generated from Mn2SiO4 during the lithiation process facilitate electron conduction, thus improving the electrode reaction kinetics. Owing to the synergetic effects, the MSS@C material exhibits a higher ICE (79.51%) compared to 60.91% of pure SiOx, and a superior cyclic performance (832 mAh g−1 at 0.5 A g−1 after 350 cycles with a capacity retention of 90.4%). This work offers a new approach to increase the ICE while improving the electrode reaction kinetics and cycling stability of SiOx-based materials.

Phosphorus, particularly the red phosphorus (RP) allotrope, has been extensively studied as an anode material in both lithium-ion batteries (LIBs) and emerging sodium-ion batteries (SIBs). RP is featured with high theoretical capacity (2,596 mA h g−1), suitable low redox potential (~0.7/0.4 V for LIBs/SIBs), abundant resources, and environmental friendliness. Despite its promises, the inherent poor electrical conductivity of RP (~10−14 S cm−1) and significant volume changes during charge/discharge processes (>300%) compromise its cycling stability. In order to address these issues, various countermeasures have been proposed, focusing on the incorporation of materials that provide high conductivity and mechanical strength in composite-type anodes. In addition, the interfacial instability, oxidation, and safety concerns and the low mass ratio of active material in the electrode need to be addressed. Herein, this review summarizes the up-to-date development in RP materials, outlines the challenges, and presents corresponding countermeasures aimed to enhance the electrochemical performance. It covers aspects such as the structural design of RP, the choice of the additive materials and electrolytes, rational electrode construction, etc. The review also discusses the future prospects of RP for LIBs/SIBs and aims to provide a different perspective on the challenges that must be overcome to fully exploit the potential of RP and meet commercial application requirements.

Abstract Arthropod-borne virus (arbovirus) and arthropod-specific virus (ASV) are viruses circulating amongst hematophagous arthropods that are broadly transmitted in ecological systems. Arbovirus may replicate in both vertebrates and invertebrates and some are known to be pathogenic to animals or humans. ASV only replicate in invertebrate arthropods yet they are basal to many types of arboviruses. We built a comprehensive dataset of arbovirus and ASV by curating globally available data from the Arbovirus Catalog, the arbovirus list in Section VIII-F of the Biosafety in Microbiological and Biomedical Laboratories 6th edition, Virus Metadata Resource of International Committee on Taxonomy of Viruses, and GenBank. Revealing the diversity, distribution and biosafety recommendation of arbovirus and ASV at a global scale is essential to the understanding of potential interactions, evolution, and risks associated with these viruses. Moreover, the genomic sequences associated with the dataset will enable the investigation of genetic patterns distinguishing the two groups, as well as aid in predicting the vector/host relationships of the newly discovered viruses.

In this paper, a narrowband bandpass filter comprising substrate integrated waveguide (SIW) and spoof surface plasmon polaritons (SSPPs) is proposed, achieving miniaturization and low insertion loss at Ka-band. SIWs and SSPPs exhibit low and high cut-off responses, respectively, which can be combined for filtering functionalities. By designing I-shaped SSPP structures with large effective length, the cut-off frequencies of SIW and SSPPs can be tailed to converge at a certain frequency for the narrowband filter, where the SIW mode functions as a quasi-evanescent mode, and the mode impedance ramps fast. A sharp funnel-shaped transition is designed to connect SIW with a large impedance and 50- $\Omega $ microstrip line for low insertion loss and a compact profile. In addition, no transitional SSPP structures are desired in the proposed devices, which further shortens the profile dimension. To verify our design, a hybrid filter at 30 GHz is fabricated and characterized. The measured insertion loss is as low as 1.5 dB, and the 3-dB bandwidth is as narrow as 3%, which shows good consistency with the simulation. The proposed SIW-SSPP device has a low profile of $0.70\,\,\lambda \times 0.38\,\,\lambda $ and may find important applications in frequency division multiplexing.

As a traditional nourishing Chinese herbal medicine, Cornus officinalis Sieb. et Zucc. has a long history of application. At present, only the flesh of the fruit of Cornus officinalis is used as a medicine, which wastes a large quantity of ingredients in the nutlet. To improve the comprehensive utilization efficiency of the fruit’s nutlet, which could be used when there is a shortage of the plant’s fruit in the market, this study used Fourier transform-infrared spectroscopy (FT-IR), gas chromatography-mass spectrometry (GC-MS), thermogravimetric (TG) analysis, pyrolysis-gas chromatography-mass spectrometry (PY-GC-MS), and nuclear magnetic resonance (NMR) techniques to analyze the Cornus officinalis nutlet. The results showed that the active ingredients of Cornus officinalis nutlet have great medicinal value and could become a substitute for the fruit. After extracting the active ingredients, the residue can be used as a good biomass liquid fuel, providing reference for the future to replace fossil fuels. This study provides the scientific basis for the comprehensive utilization of high-quality resources for Cornus officinalis.

Abstract Background We attempted to estimate dietary vitamin A requirements based on dietary vitamin A intake in well-nourished Chinese children with adequate liver vitamin A reserves. Methods A cross-sectional study was conducted in a kindergarten and an elementary school in Shiyan city, Hubei province of China from December 2009 to July 2010. After screening, 60 children (22 aged 4 ~ 6 y and 38 aged 7 ~ 9 y) were randomly subjected to a 3-d or 18-d deuterated-retinol-dilution (DRD) procedure to evaluate the vitamin A reserves in the body and liver. Dietary intakes of vitamin A were estimated from two (one in winter and one in summer) consecutive 3-day weighed food records and dietary recalls. Results The dietary vitamin A intakes were significantly correlated with vitamin A stores in the body and liver, but not with the serum level of retinol. The dietary vitamin A intakes were 476.9 ± 196.7 µg retinol equivalent (RE) (or 377.7 ± 166.2 µg retinol activity equivalent (RAE)) / day for 4 ~ 6 y children and 529.1 ± 87.2 µg RE/d (or 464.0 ± 81.1 µg RAE/d) for 7 ~ 9 y children with adequate liver vitamin A reserves. The estimated liver stores of vitamin A derived from both time points (3-d and 18-d) were similar. Conclusion Adequate dietary vitamin A intakes among the well-nourished Chinese children were estimated to be 477 µg RE/d (95%CI 385 ~ 570) or 378 µg RAE/d (95%CI 304 ~ 441) for 4 ~ 6 y children and 529 µg RE/d (95%CI 500 ~ 560) or 464 µg RAE/d (95%CI 437 ~ 491) for 7 ~ 9 y children. Although it needs to be verified in a larger population of different regions in China, our results provide important data to establish the dietary requirement of vitamin A specifically for Chinese children.

R-CHOP chemotherapy has been established as the first-line standard treatment for elderly patients diagnosed with diffuse large B-cell lymphoma. However, an increased risk of Pneumocystis jirovecii pneumonia in diffuse large B-cell lymphoma patients after the rituximab-based chemotherapy has been reported. We describe a case who developed intermittent cough, fever and shortness of breath after five cycles of R-CHOP treatment for diffuse large B-cell lymphoma. A rapid deterioration in patient’s respiratory condition prompted us to adopt an aggressive anti- Pneumocystis jirovecii pneumonia strategy that combined the conventional trimethoprim/sulfamethoxazole and another two antimicrobials, caspofungin and clindamycin. This is the first report mentioning the successful treatment of severe Pneumocystis jirovecii pneumonia with a triple-drug regimen in a HIV-uninfected patient. The aim of our report is also to emphasize that early and correct diagnosis of Pneumocystis jirovecii pneumonia in immunocompromised HIV-uninfected patients is very important. Relevant oncologists should be alert to the risk of Pneumocystis jirovecii pneumonia in patients receiving R-CHOP chemotherapy.

PurposeThis study aims to investigate the glymphatic system activity changes in patients with mild traumatic brain injury (mTBI), particularly in MRI-negative patients, using analysis along the perivascular space (ALPS) technology.MethodsA total of 161 mTBI patients (age: 15–92 years old) and 28 healthy controls (age: 15–84 years old) were included in this retrospective study. The mTBI patients were divided into MRI-negative and MRI-positive groups. ALPS index was calculated automatically using whole-brain T1-MPRAGE imaging and diffusion tensor imaging. The Student's t and chi-squared tests were performed to compare the ALPS index, age, gender, course of disease, and Glasgow Coma Scale (GCS) score between groups. Correlations among ALPS index, age, course of disease and GCS score were computed using Spearman's correlation analysis.ResultsIncreased activity of the glymphatic system was suggested in mTBI patients based on ALPS index analysis, including the MRI-negative patients. There was a significant negative correlation between the ALPS index and age. In addition, a weak positive correlation between the ALPS index and course of disease was also observed. On the contrary, there was no significant correlation between the ALPS index and sex nor between the ALPS index and GCS score.ConclusionOur study demonstrated that the activity level of the glymphatic system was enhanced in mTBI patients, even when their brain MRI scans were negative. These findings may provide novel insights for understanding the pathophysiology of mild TBI.

Epigastric heteropagus twins are an extremely rare congenital anomaly of conjoined twins. We present a case of epigastric heteropagus twins who were diagnosed via prenatal ultrasound imaging: the fetus (or host) was connected to the abdominal wall of the parasite (the dependent portion), and an omphalocele was present. The male infant was delivered by cesarean section at 35 + 5 weeks gestation. The parasite lacked a head and heart and presented long bones of the limbs. After abdominal computed tomography, omphalocele repair, and parasite removal were surgically performed under general anesthesia. After discharge (follow-up, 3 months), the infant is currently growing well and is healing satisfactorily. Forty-one cases of epigastric heteropagus twins were retrieved from database searches: 38 good postoperative outcomes, 2 perioperative deaths, and 1 termination. The case highlights that even when parasites are massive in size, births can present good outcomes with suitable surgical treatment.

Taking the roadway peripheral rock anchoring unit as the research object, the rock compression test containing the anchor solid was carried out to analyze the influence of the degree of peripheral rock fragmentation and the anchor support method on the mechanical properties of the rock body. The test results showed that the smaller the size of the structural surface, the more a greater number of anchor rods were needed, which in turn provided better support. With the increase in the size of the structural surface, the uniaxial compressive strength and modulus of elasticity of the specimen showed a gradual decrease. Numerical tests of the uniaxial compression of rock containing cohesive units showed that the deformation of the specimen near the anchor bar was significantly reduced, while the main rupture surface was blocked, and an obvious reinforcement zone was formed near the anchor bar. Under the double-anchor condition, the anchor tension stress was more obvious, the reinforcement zone was wider, and the rock rupture surface was strongly blocked, all of which made its reinforcement effect the more obvious. This double-anchor condition showed that the anchoring effect of the anchor rods on the specimens was reflected in two aspects of reinforcement and crack stopping. The denser the anchor rods, the wider the reinforcement zone and hence the more likely that the superposition effect will occur, which allowed the anchor rods to play a greater supporting role in stabilizing the rock. The research results can provide a theoretical basis for the design of anchor support and early warning prediction of destabilization damage in the fractured surrounding rock of coal mine roadways.

The present study suggests a new approach to optimal output voltage estimation of the proton exchange membrane fuel cell (PEMFC) based on a new optimized Elman Neural Network (ENN). Based on the proposed method, the ENN has been optimized based on a new version of the improved metaheuristic method, called Quantum Water Strider Algorithm (QWSA), and is utilized to define the main parameters of the ENN. The purpose is for minimizing the error value between the measured and the predicted output voltages of the PEMFC. To illustrate the advantage of the suggested model, its results on test equipment are compared with some other methods from the literature including genetic algorithm-based, Fluid search optimization-based, and the original WSA to indicate its effectiveness. The results showed that the proposed method with 0.0466 absolute error has the best agreement with the real value. The genetic algorithm-based, the Fluid search optimization algorithm-based, and the original WSA-based methods with 0.0574, 0.0658, and 0.0742 absolute error are in the next ranks

Toroidal droplets are inherently unstable in viscous oils; they either shrink to a single drop or break into several spherical droplets due to Rayleigh–Plateau instability. In this paper, the breakup dynamics of toroidal droplets in immiscible viscous oils have been numerically investigated. A two-dimensional model combined level-set method is proposed. Numerical results reveal that the initial aspect ratios, interfacial tensions, and outer liquid viscosities play important roles in determining the breakup dynamics of toroidal droplets. The initial aspect ratios dominate the number of split droplets, which is consistent with a linearly scaling law n = 0.57 R0/a0. By considering key factors of interfacial tension in this process, it is found that interfacial tension is crucial in the initial morphology of the toroidal droplet and helps to retard the unstable breakup dynamics. Interestingly, reducing the interfacial tension stabilizes it against breakup. We further study the effect of viscosity on the breakup dynamics. The surrounding viscous oils contribute to stabilizing the interfacial-tension-driven instabilities and extending the breakup time. Thus, for a toroidal droplet in high viscosity oils and a sufficiently low interfacial tension system, the unstable breakup dynamics could be delayed. Our findings provide a novel fundamental understanding of toroidal droplets and are beneficial to applications involving the manipulation of toroidal droplets.

Commonly used peroxydisulfate (PS) or peroxymonosulfate (PMS) activation methods have been limited in their practical application due to certain drawbacks, such as high cost, high energy consumption and secondary pollution. In this study, a catalyst-free alizarin green (AG) self-activating PMS catalytic system was constructed based on photosensitization properties of dye, which ultimately achieved efficient degradation of the dye activator, also the target pollutant. Here, 52.5% of the 100 mL mixture of 10 mg/L AG decomposed within 60 min with 1 mM PMS under visible-light irradiation, thereby showing a strong pH adaptation. Mechanism of AG self-activating PMS was revealed that the photo-excited AG can effectively transfer photo-induced electrons to PMS for its activation, which generates reactive oxidizing species dominated by singlet oxygen (1O2), and supplemented by hydroxyl radical (•OH), superoxide radical (O2•−) and sulfate radical (SO4•−) to realize the efficient self-degradation of the dye pollutants. Moreover, such self-catalytic system operated well under natural sunlight irradiation, indicating the great application potential in the actual wastewater treatment. Herein, photosensitive dye acted as an ideal PMS activator realizing its efficient self-degradation, which provides a novel idea of “using waste to treat waste” for developing wastewater treatment process in a high-efficiency and low-consumption way.

Chronic asthma is characterized by airway inflammation and irreversible airway remodeling. Epithelial-mesenchymal transition (EMT) is a typical pathological change of airway remodeling. Our previous research demonstrated miR-23b inhibited airway smooth muscle proliferation while the function of miR-23b-3p has not been reported yet. Besides, miRNA is regulated by many factors, including DNA methylation. The function of miR-23b-3p and whether it is regulated by DNA methylation are worth exploring. Balb/c mice were given OVA sensitization to develop the asthmatic model. Expression of miR-23b-3p and EMT markers were measured by RT-qPCR, WB and immunohistochemistry (IHC). DNA methylation was detected by methylation-specific PCR (MSP) and the MassARRAY System. Asthmatic mice and TGF-β1-stimulated bronchial epithelial cells (BEAS-2B) showed EMT with increased miR-23b-3p. Overexpression of miR-23b-3p promoted EMT and migration, while inhibition of miR-23b-3p reversed these transitions. DNA methyltransferases were decreased in asthmatic mice. MSP and MassARRAY System detected the promotor of miR-23b showed DNA hypomethylation. DNA methyltransferase inhibitor 5’-AZA-CdZ increased the expression of miR-23b-3p. Meanwhile, PTEN was identified as a target gene of miR-23b-3p. Our results indicated that promotor hypomethylation mediated upregulation of miR-23b-3p targets PTEN to promote EMT in chronic asthma. miR-23b-3p and DNA methylation might be potential therapeutic targets for irreversible airway remodeling.

Na3V2(PO4)3 has been considered as the most promising cathode material for sodium-ion batteries because of its suitable sodium insertion/extraction plateau and good cycling stability. However, the inferior rate-capability resulting from the lower electronic conductivity restricts its commercial application. To address this issue, niobium ions (Nb5+) are introduced to partially substitute V3+ for generating V-mixed valence, ensuring the material with improved intrinsic electronic conductivity. Herein, nano-sized Na3V2−xNbx(PO4)3/C (x = 0, 0.05, 0.1, 0.2) materials with a core–shell structure are prepared via a simple sol–gel method. The optimized Na3V1.9Nb0.1(PO4)3/C material shows a high specific capacity (∼114 mA h g−1 at 0.5C), a superior rate-capability (∼100 mA h g−1 at 20C), and an excellent long-term cycling stability (a specific capacity of 74.7 mA h g−1 over 1000 cycles at 50C, corresponding to a capacity decay rate of 0.0258%/cycle). The improved cycling performance is mainly attributed to the enhanced intrinsic electronic conductivity and Na+ mobility, and the reduced charge-transfer resistance, as confirmed by the first-principles calculations, cyclic voltammetry, and electrochemical impedance spectra analysis. The constructed fast electron network, from the surface to the bulk, combining with the nano-sized feature, contributes to the facilitated electrode reaction kinetics and, thus, ensures improved rate-capability.

This study investigates the law of stress field and fracture field of the surrounding rock at the trick rise of the mining area affected by strong mining. It is found that as the working face continues to approach, large-scale cracks occur in the surrounding rock on the track rise. In particular, when the working face crosses the track rise, the equivalent stress τoct concentration area expands, gradually intersecting with the surrounding rock concentration area of the roadway. It indicates that the working face advancement caused a dramatic change in the stress field of the roadway envelope, which will have an immediate adverse effect on the track rise. With comprehensive support costs, economic efficiency, and other factors, the working face will no longer cross the track rise, and the stopping line is roughly controlled at -20 m so that the track rise can serve other working faces for a long time. The reinforcement support scheme of “anchor mesh spray + grouting anchor” is proposed for the key areas such as arch shoulder. Through the analysis of the field monitoring of the roadway surface displacement, the deformation of the roadway surrounding rock showed a change trend of increasing first and then stabilizing with time, which indicates that the support effect was good and greatly improved the stability and safety of the roadway.

Based on the thermodynamic and elastodynamic theories, the controlling equation of temperature-stress coupling action on rocks containing random damage units is established by combining the Mogi-Coulomb damage criterion. And the numerical calculation model of combustion cavity expansion under temperature-stress coupling condition is established by using ABAQUS secondary development program. The fracture field evolution law during the expansion of the gasification cavity was studied under two conditions: perpendicular to (condition 1) and along the intermediate principal stress (condition 2). It is found that under the condition 1, the gasification cavity gradually forms a smaller fracture circle, while the surrounding rock at the floor of the gasification cavity generates a wide range of equivalent damage areas under the condition 2, which is unfavorable for practical engineering. The condition 1 deployment scheme is more practical in terms of the degree of rupture and the subsequent gasification process. The gasification cavity is obviously affected by the horizontal stress. When the horizontal stress is small, the stability of the surrounding rock is seriously damaged. It is necessary to fully consider the influence of in situ stress in the layout of the gasification cavity; at the same time, measures are added to the process to reduce the degree of rupture of the surrounding rock. The evolution law of the temperature field and rupture field of the surrounding pressure in the combustion cavity during the whole process of UCG was numerically simulated. The floor rupture zone develops gradually with the advancement of the working face of the combustion cavity, and deeper rupture zones appear in several areas, which need special attention in the engineering.

Electromagnetically induced transparency (EIT) metamaterials (MTMs) based on the bright-dark mode theory have gained great interest in slow light, sensing, and energy storage in recent years. Typically, various split ring resonators with magnetic response have been proposed as dark resonators in EIT MTMs. Here, we have employed a cut-wire (CW) and two electric-field-coupled inductor-capacitor (ELC) resonators with a pure electrical response on a liquid crystal polymer (LCP) substrate with a low loss tangent to fulfill the EIT effect in the terahertz (THz) region. The former works as the bright mode, and the latter functions as the dark mode. The EIT phenomenon results from the destructive interference between these two modes, which can be verified by numerical simulation and near field distribution. In addition, a Lorentz oscillator model was studied to quantitatively analyze the relationship between the coupling strength and the coupling distance. As a demonstration, an EIT MTM device with 5000 units was fabricated and characterized, which showed a transmission window with a peak value of 0.75 at 0.414 THz. This work may inspire new multifunctional EIT MTMs, especially the flexible applications at THz frequencies.

Segmentation of layers in retinal images obtained by optical coherence tomography (OCT) has become an important clinical tool to diagnose ophthalmic diseases. However, due to the susceptibility to speckle noise and shadow of blood vessels etc., the layer segmentation technology based on a single image still fail to reach a satisfactory level. We propose a combination method of structure interpolation and lateral mean filtering (SI-LMF) to improve the signal-to-noise ratio based on one retinal image. Before performing one-dimensional lateral mean filtering to remove noise, structure interpolation was operated to eliminate thickness fluctuations. Then, we used boundary growth method to identify boundaries. Compared with existing segmentations, the method proposed in this paper requires less data and avoids the influence of microsaccade. The automatic segmentation method was verified on the spectral domain OCT volume images obtained from four normal objects, which successfully identified the boundaries of 10 physiological layers, consistent with the results based on the manual determination.

This study presents different land saving and loss reducing schemes. Comprehensively compare the economic benefits of the schemes. It is shown that the optimal scheme can recover tons of coal resources on the south slope, creating significant economic benefits. Numerical simulation was utilized to analyze the changes of slope stability, deformation, and shear strain increment in the process of land saving and loss reducing. Results found that the slope stability decreases rapidly, and the toe of the slope has to be internally discharged in time to compress the slope. Timely follow-up of in-slope rows can improve slope stability. The position of the slope shear exit changes with the increase of the distance of the inner row, and its stability increases gradually. When the distance of the lower inner row exceeds 120 m, the increase of the internal row distance has little influence on the slope stability. When the inner distance exceeds 60 m in the process of internal dumping of upper platform, the position of potential sliding plane gradually changes from the lower dump to the upper and lower dump with the increase of inner dumping distance. It shows that the stability of the dump will be damaged if the upper dump continues to be discharged. Therefore, the distance between the upper and lower dump sites is more important than 60 m. The stability of the south slope is good in the process of mining and internal drainage, and the overall stability of the south slope is controllable, based on slope radar monitoring.

The strength criterion is an extremely important basis for evaluating the stability of surrounding rock and optimizing the support pressure design. In this paper, nine different strength criteria are summarized and simplified based on the reasonable assumption. Then, a new unified criterion equation is established, which includes all strength theories proposed by this paper. Meanwhile, a new unified closed-form solution for circular opening based on the newly proposed unified criterion equation is deduced with the infinite and finite external boundary combining with the nonassociative flow rule under plane strain conditions. In the plastic zone, four different elastic strain assumptions are applied to solving the plastic zone deformation considering the effect of rock mass damage. The solution’s validity is also verified by comparison with the traditional solution. Finally, the influences of strength criteria, dilation coefficient, elastic strain form of plastic zone, and rock mass damage on the mechanical response of surrounding rock are discussed in detail. The research result shows that TR and VM criteria give the largest plastic zone radius, followed by IDP, MC, and MDP criteria, and seem to underestimate the self-strength of rock mass; The CDP criterion gives the smallest plastic zone radius and may overestimate the self-strength of rock mass; UST0.5, GSMP, GMC, and GLD criteria that reasonably consider the effect of internal principal stresses give an intermediate range and can be strongly recommended for evaluating the mechanics and deformation behavior of surrounding rock; as the dilation coefficient gradually increases, the dimensionless surface displacement presents the nonlinear increase characteristics; the deformation of plastic zone and the ground response curve, which are closely related to the strength criteria, are also greatly influenced by the elastic strain assumption in the plastic zone and rock mass damage degree. The assumption that the elastic strain satisfies Hook’s law (Case 3) may be more reasonable compared with the continuous elastic strain (Case 1) and thick-walled cylinders (Case 2) assumptions; in addition, the Young’s modulus power function damage model seems to give more reasonable solution for the deformation of plastic zone and is suggested to be a preferred method for solving plastic displacement. The research results can provide very important theoretical bases for evaluating the tunnel stability and support design reliability of different lithology rock masses in underground engineering.

Excavation disturbance on the dynamic variation of the three-dimensional stress field is the main cause for the dynamic disasters of the surrounding rock mass of the roof. The stress condition in the surrounding rock mass of the roof during entry excavation and its impact on entry stability are systemically studied in this study. It is found that the surrounding rock mass of the roof is mainly influenced by the combined effect of the stress unloading and stress transference induced by entry excavation. A servo-controlled true triaxial material testing system is used to conduct the true triaxial loading and unloading experiments of rocks under different stress paths. The influence of different stress paths, especially the variation of the principal stress direction, on the mechanical characteristics and fracture characteristics of rocks is investigated. The results indicate that the variation of the principal stress direction has a significant impact on the macroscopic fracture characteristics of the rock. The main macroscopic fracture plane of the rock highly depends on the intermediate principal stress. The fracture evolution of the roof rock mass during entry excavation is analyzed. The results show that the change of the three-dimensional stress field induces the formation of complex fracture networks in the surrounding rock mass of the roof. The roof is likely to dislocate horizontally and collapse. The corners of the entry are seriously damaged. Based on the above findings, a support scheme is proposed to maintain the stability of a gob-side entry. The field experience suggests that the support scheme can achieve good results.

The cracking process in rock or concrete is usually characterized by the formation of microcracks that eventually form a propagating macrocrack. A series of three-point bending experiments were performed on sandstone containing Mode I crack under different loading rates. The microscopic monitoring system was established to capture the cracking process at notch tip. The loading rate dependence of microcracking behaviour was analysed based on load-time curves, acoustic emission (AE), microscopic images, and micrograph-based digital image correlation (DIC) technology. Results showed that the specimens underwent a short period of compression and elastic deformation stage under high loading rate, and the peak loads increased with the increase in loading rate. The AE results revealed that the fracturing process can be divided into elastic stage, damage stage, and postpeak stage, and more extensive damage occurred before the peak under low loading rate. It can be observed from microscopic images that the crack was initiated during the elastic stage, which was earlier than that determined from the AE monitoring. In addition, the microcracks were initiated at multiple locations and were mainly located at the interfaces between dense grains under low loading rate, while microcracks were observed inside the grains under high loading rate. Furthermore, the DIC results showed that the crack opening displacement (COD) of 0.6 mm/min at the peak was almost twice than that of 3.0 mm/min. The COD under the same loading rate at the peak can be considered as the material property of sandstone.

The study of deformation, strength, and other mechanical characteristics of sandstone under true triaxial compression is significant for understanding failure mechanisms in rock and evaluating the stability of underground structures. Conventional and true triaxial compression tests for sandstone are conducted for different stress states in this study using the self-developed true triaxial electrohydraulic servo test system combined with acoustic emission (AE) testing. This study presents an in-depth and systematic investigation of deformation, strength, and AE characteristics. The results show significant differences in deformation, strength, and acoustic emission characteristics for the rock under conventional triaxial and true triaxial compression tests, respectively. The peak strength, axial strain, lateral strain, and incremental strain (in unstable crack growth stage) increase with increasing confining pressure under conventional triaxial compression, and the AE count gradually decreases while shear crack proportion gradually increases, indicating that increasing confining pressure gradually inhibits the shear slip effect along fractures, delays perforation of the rock shear fracture surface, and enhances the ability of the rock to withstand deformation and load. Under true triaxial compression, the peak strength increases and then decreases with increasing intermediate principal stress σ2 and the axial strain ε1 and lateral strain ε2 gradually decrease; besides, the lateral strain (expansion) of the rock is mainly in the minimum principal stress σ3 direction, and lateral expansion tends to decrease before increasing. AE events first weaken and then enhance with increasing σ2, and the proportion of shear cracks increases first and then decreases, indicating that the confining pressure gradually changes from the shear slip effect that controls crack offset to the damage effect that promotes crack tension with increasing σ2. In addition, the protective effect of confining pressure improves when σ3 increases.