Structural State Research Articles

An Integrated Petrographic, Geomatic and Geophysical Approach for the Characterization of the Carbonate Rocks of the Calcari di Cagliari Formation

Non-invasive techniques, such as close-range photogrammetry (CRP) and 3D ultrasonic tomography complemented with optical and scanning electron microscopy and mercury porosimetry, were applied to characterize the carbonate rock samples of the Calcari di Cagliari formation. The integrated approach started with the computation of high-resolution 3D models of the carbonate samples using the CRP technique to produce 3D high-resolution models texturized both with natural colors and intensity. Starting from the 3D models from previous techniques, a 3D ultrasonic tomography on each rock sample was accurately planned and carried out in order to detect the elastic properties of such rocks and relate them to textural heterogeneity or internal defects. The results indicate that the relationship between longitudinal velocity and rock properties is complex even in the same carbonate formation. Understanding the relationship between the geomatic and geophysical responses in the investigated rock properties, such as textural characteristics and especially structure and geometry of pores, type of pores, tortuosity and cementing material, is important for many practical applications and especially in the diagnostic process of the conservation state of monumental structures. The integration of the above non-invasive techniques complemented by petrographical–petrophysical data proved to be a powerful method to associate each lithotype with a different susceptibility to degradation. The results presented in this paper demonstrate that the proposed integrated use of complementary methodologies would guarantee the reproducibility of the measurements both at the laboratory and field scale for the monitoring in time of the rock condition while giving a useful contribution in making decisions on an appropriate remedial strategy.

Machine learning for efficient grazing-exit x-ray absorption near edge structure spectroscopy analysis: Bayesian optimization approach

In materials science, traditional techniques for analyzing layered structures are essential for obtaining information about local structure, electronic properties and chemical states. While valuable, these methods often require high vacuum environments and have limited depth profiling capabilities. The grazing exit x-ray absorption near-edge structure (GE-XANES) technique addresses these limitations by providing depth-resolved insight at ambient conditions, facilitating in situ material analysis without special sample preparation. However, GE-XANES is limited by long data acquisition times, which hinders its practicality for various applications. To overcome this, we have incorporated Bayesian optimization (BO) into the GE-XANES data acquisition process. This innovative approach potentially reduces measurement time by a factor of 50. We have used a standard GE-XANES experiment, which serve as reference, to validate the effectiveness and accuracy of the BO-informed experimental setup. Our results show that this optimized approach maintains data quality while significantly improving efficiency, making GE-XANES more accessible to a wider range of materials science applications.

Female CEOs and SME’s financing decision: evidence from firm-level data

PurposeThis study investigates the relationship between female CEOs and SMEs’ financing decisions. The study also examined the moderating role of ownership structure (female, foreign, and state ownership) in female CEO-SMEs’ financing decisions.Design/methodology/approachThe study has applied Generalized Least Square (GLS) and Binomial Logistic Regression. The study has used firm-level data from 2,700 Small and Medium Enterprises (SMEs) in the Chinese economy.FindingsThe results suggest that female CEOs use debt financing. However, the financing decision of female CEOs varies if we account for female ownership, foreign ownership, state ownership, firm association with big firms, and the industry in which the firm operates. This study also provides robust evidence that female CEOs utilize debt financing under certain conditions and that female CEOs prefer long-term debt financing to short-term debt financing when considering debt maturity choices.Originality/valueRecent studies report a negative relationship between female CEOs and financing decisions based on the rationale that females are risk-averse and choose less risky financing compared to their male counterparts. This study posits new evidence that female CEO financing decisions are not always risk averse if we consider female ownership, foreign ownership, state ownership, firm association with big firms, and the industry in which the firm operates. Thus, we contribute to the corporate governance literature, and this study implies a corporate financing policy.

Mo-doping modulated cationic vacancy in Zn3V2O8 with enhanced electrochemical performance for lithium-ion batteries

Given diverse redox reactions and abundant raw materials, Zn3V2O8 with high specific capacity is considered as a potential anode material for lithium-ion batteries. Same as other transition metal oxides, Zn3V2O8 suffers from infertile conductivity, sluggish ion diffusion and fast capacity loss derived from volume expansion during discharge/charge process, further hindering its application. In this work, a novel Mo doped Zn3V2O8 (Zn3V2-xMo5x/6O8) anode material with cationic vacancy (V vacancy) has been designed through a facile sol-gel method. It is found that a small Mo-doping amount has nearly no influence on the crystal structure, morphology and element valence states of Zn3V2O8. Mo doped Zn3V2O8 samples possess smaller charge transfer resistance and higher lithium ion diffusion coefficient. The results of electrochemical performance illustrate that Mo doped Zn3V2O8 can deliver higher reversible specific capacities and better rate capability compared with Zn3V2O8, which can be ascribed to the introduction of V vacancy. In particular, when Mo-doping amount is set as 0.03, the obtained Zn3V1.97Mo0.025O8 exhibits a reversible capacity of 481.1 mAh g−1 after 600 cycles at 1 A g−1. It is believed that this work could provide an effective and feasible strategy to construct high performance transition metal vanadate anode materials for lithium-ion batteries.

Mixed polyanionic NaFe1.6V0.4(PO4)(SO4)2@CNT cathode for sodium-ion batteries: Electrochemical diffusion kinetics and distribution of relaxation time analysis at different temperatures

We report the electrochemical sodium-ion kinetics and distribution of relaxation time (DRT) analysis of a newly designed mixed polyanionic NaFe1.6V0.4(PO4)(SO4)2@CNT composite as a cathode. The specific capacity of 104 mAhg−1 is observed at 0.1 C with the average working voltage of ∼3 V. Intriguingly, a remarkable rate capability and reversibility are demonstrated up to very high current rate of 25 C. The long cycling test up to 10 C shows high capacity retention even after 2000 cycles. The detailed analysis of galvanostatic intermittent titration technique (GITT) and cyclic voltammetry (CV) data reveal the diffusion coefficient of 10−8–10−11 cm2s−1. We find excellent stability in the thermal testing between 25–55 °C temperatures and 80% capacity retention up to 100 cycles at 5 C. Further, we analyze the individual electrochemical processes in the time domain using the novel DRT technique at different temperatures. The ex-situ investigation shows the stable and reversible structure, morphology and electronic states of the long cycled cathode material. More importantly, we demonstrate relatively high specific energy of ≈155 Wh kg−1 (considering the total active material loading of both the electrodes) at 0.2 C for full cell battery having excellent rate capability up to 10 C and long cyclic stability at 1 C.

Changes in the state of matter of KCIO4 to improve thermal and combustion properties of Al/MoO3 nanothermite

To improve the thermal and combustion properties of nanothermites, a design theory of changing the state of matter and structural state of the reactants during reaction was proposed. The Al/MoO3/KClO4 (Kp) nanothermite was prepared and the Al/MoO3 nanothermite was used as a control. SEM and XRD were used to characterize the nanothermites; DSC was used to test thermal properties; and constant volume and open combustion tests were performed to examine their combustion performance. Phase and morphology characterization of the combustion products were performed to reveal the mechanism of the aluminothermic reaction. The results show that the Al/MoO3/Kp nanothermite exhibited excellent thermal properties, with a total heat release of 1976 J·g− 1, increasing by approximately 33% of 1486 J·g− 1 of the Al/MoO3 nanothermite, and activation energy of 269.66 kJ·mol− 1, which demonstrated higher stability than the Al/MoO3 nanothermite (205.64 kJ·mol− 1). During the combustion test, the peak pressure of the Al/MoO3/Kp nanothermite was 0.751 MPa, and the average pressure rise rate was 25.03 MPa·s− 1, much higher than 0.188 MPa and 6.27 MPa·s− 1 of the Al/MoO3 nanothermite. The combustion products of Al/MoO3 nanothermite were Al2O3, MoO, and Mo, indicating insufficient combustion and incomplete reaction, whereas, the combustion products of Al/MoO3/Kp nanothermite were Al2O3, MoO, and KCl, indicating complete reaction. Their “coral-like” morphology was the effect of reactants solidifying after melting during the combustion process. The characterization of reactants and pressure test during combustion reveals the three stages of aluminothermic reaction in thermites. The excellent thermal and combustion performance of Al/MoO3/Kp nanothermite is attributed to the melt and decomposition of Kp into O2 in the third stage. This study provides new ideas and guidance for the design of high-performance nanothermites.

Assessment of the Fracture Toughness of Elastoplastic Materials Based on the Structure State at the Crack Tip

Assessment of the Fracture Toughness of Elastoplastic Materials Based on the Structure State at the Crack Tip

Tumor-repopulating cells evade ferroptosis via PCK2-dependent phospholipid remodeling.

Whether stem-cell-like cancer cells avert ferroptosis to mediate therapy resistance remains unclear. In this study, using a soft fibrin gel culture system, we found that tumor-repopulating cells (TRCs) with stem-cell-like cancer cell characteristics resist chemotherapy and radiotherapy by decreasing ferroptosis sensitivity. Mechanistically, through quantitative mass spectrometry and lipidomic analysis, we determined that mitochondria metabolic kinase PCK2 phosphorylates and activates ACSL4 to drive ferroptosis-associated phospholipid remodeling. TRCs downregulate the PCK2 expression to confer themselves on a structural ferroptosis-resistant state. Notably, in addition to confirming the role of PCK2-pACSL4(T679) in multiple preclinical models, we discovered that higher PCK2 and pACSL4(T679) levels are correlated with better response to chemotherapy and radiotherapy as well as lower distant metastasis in nasopharyngeal carcinoma cohorts.

The coexistence of halal food products in non-Muslim communities: visiting Kupang cases, Indonesia

Purpose This study aims to revisit the practice of multiculturalism within the co-existence of halal food products in non-Muslim communities in Kupang, East Nusa Tenggara, Indonesia. Design/methodology/approach Data were collected through observations, interviews and documentation using a case study approach. Findings The important findings in the existing study indicate that social practice related to the acceptance and expression of non-Muslim communities towards halal products and certificates is integrated into the daily life of the people. It has contrasted with other regions in Indonesia where debates between cultural and structural aspects of halal product studies and certification prevail, often dominated by ego-sectoral interests and Islamic theology. Although Kupang’s predominantly non-Muslim population, the practice and model of halal products emerge with uniqueness within communal traditions and socio-cultural practices take precedence over structural factors. Research limitations/implications The most significant contribution of this research lies in mutual understanding, interfaith dialogue and religiosity that have fused into social life, specially building social coexistence in halal products. Practical implications These findings contribute to policymakers to reformulate halal certification and products, which are not solely driven by the interests of the Muslim community. Originality/value This study presents a new synthetic theory about halal products, confirming a case study in Kupang where non-Muslim communities accepted halal products as a reflection of cultural and local customs. This acceptance has led to the development of a new identity without contradictions among business interests, ideologies, sectoral aspects, hygiene, health and structural state movements.

Train-induced vibration response reconstruction for bridge damage detection with a deep learning methodology

Sensor malfunctions in bridge structural health monitoring system (BSHMS) could cause the missing of measured data, reducing the accuracy of damage detection. It is of great significance to reconstruct the data of faulty sensors with measured data of well-functioning sensors for bridge structural state assessment. In this paper, a train-induced vibration response reconstruction approach for bridge damage detection is proposed. An enhanced deep densely connected neural network (ED-DCNN) introducing a multi-head self-attention mechanism and a skip connection is designed to reconstruct the missing bridge responses, aiming to improve the vibration correlation between the faulty sensors and good sensors and benefit the learning of temporal and spatial features of responses. Then to further validate the accuracy and reliability of the ED-DCNN, an alternate down-sampling residual network (AD-ResNet) is built to identify bridge damage with the complete responses, including the reconstructed ones and the measured, which extracts the structural damage features at different scales utilizing different types of residual blocks in an alternating manner. The efficiency and robustness of the two networks are comprehensively studied using the collected acceleration data from a heavy-haul railway bridge, considering different noise levels. The results demonstrate that under various conditions, the reconstructed responses match the real responses well in time domain, with a low RMSE below 0.4% and a high correlation coefficient of 0.9744, which indicates that the incorporation of a multi-head self-attention module effectively improves the construction of correlations between responses. Additionally, the natural frequencies of bridge are accurately identified from the reconstructed responses. In terms of bridge damage detection, taking both the measured and reconstructed responses as inputs, the identification accuracy obviously improves by 33.57% compared to cases without the reconstructed responses, further emphasizing an excellent reconstruction capability of the ED-DCNN.

Visualizing the gas-sensitive structure of the CuZn surface in methanol synthesis catalysis

Methanol formation over Cu/ZnO catalysts is linked with a catalytically active phase created by contact between Cu nanoparticles and Zn species whose chemical and structural state depends on reaction conditions. Herein, we use variable-temperature scanning tunneling microscopy at elevated pressure conditions combined with X-ray photoelectron spectroscopy measurements to investigate the surface structures and chemical states that evolve when a CuZn/Cu(111) surface alloy is exposed to reaction gas mixtures. In CO2 hydrogenation conditions, Zn stays embedded in the CuZn surface, but once CO gas is added to the mixture, the Zn segregates onto the Cu surface. The Zn segregation is CO-induced, and establishes a new dynamic state of the catalyst surface where Zn is continually exchanged at the Cu surface. Candidates for the migrating few-atom Zn clusters are further identified in time-resolved imaging series. The findings point to a significant role of CO affecting the distribution of Zn in the multiphasic ZnO/CuZn/Cu catalysts.

Coastal Erosion and Military Heritage in Latvia

Water often needs protection, but heritage can also require protection from water. The remains of a military fortification complex in the Latvian city of Liepāja are slowly being swallowed by the sea, a case where military heritage meets water heritage. To what extent should these ruins be protected from water and is preservation still possible? Both the coastal defense structures and the sea have been considered symbols of the city, attracting locals and visitors. Yet, over time, the monumental structures have been threatened by environmental challenges triggered by rising sea levels and ongoing coastal erosion. This has led to the deterioration of the structures and the loss of their structural integrity. Although the effects of the natural processes cannot be prevented entirely, they could be delayed. However, the rapidly deteriorating state of the coastal military structures has not resulted in a sense of urgency among local authorities. The article highlights the importance of the military structures in the local context as military, cultural heritage and the water challenges faced by the coastal defense line. It also explores the potential for, and impediments to, the structures’ preservation.

O vacancy-rich doped WO3/GF as a novel electrode for an aqueous DHAQ/ K4Fe(CN)6 redox flow battery

In this study, a graphite felt (GF) electrode was modified with N and S heteroatoms before being loaded with Ti-doped or Nb-doped WO3 to produce Ti-WO3/GF-N-S and Nb-WO3/GF-N-S electrodes. X-ray diffraction, scanning electron microscopy, and X-ray photoelectron spectroscopy were used to analyze the crystal structure, morphology, and elemental state of the modified GF electrodes and investigate the impact of nonmetallic and metallic element doping. The influence of metal doping on the electronic distribution of the oxide was determined using first-principle calculations. The electrochemical properties of the modified GF were studied using cyclic voltammetry, electrochemical impedance spectroscopy, and single-cell tests. The results showed that Ti or Nb doping changed the energy band structure, bond length, and bond angle in the WO3 crystal and formed O vacancies. The chemical properties of Ti and Nb resulted in different numbers of O vacancies for the two doped-WO3.The doping of N and S heteroatoms on the carbon fibres altered the O vacancy concentration of WO3. The synergism between the two doping methods accelerated electron transfer in the anthraquinone redox reaction. In addition, the N-containing functional groups provide lone-pair electrons, which accelerate electron transfer and anthraquinone adsorption. Therefore, compared to the pristine GF, the discharge capacities of the Ti-WO3/GF-N-S and Nb-h-WO3/GF-N-S graphite GF electrodes increased by 58 % and 41 %, respectively, and the Nb-h-WO3/GF-N-S graphite GF electrodes exhibited a good capacity retention rate. This study broadens the practical applications of aqueous anthraquinone redox flow batteries.

Systematic identification of structure-specific protein-protein interactions.

The physical interactome of a protein can be altered upon perturbation, modulating cell physiology and contributing to disease. Identifying interactome differences of normal and disease states of proteins could help understand disease mechanisms, but current methods do not pinpoint structure-specific PPIs and interaction interfaces proteome-wide. We used limited proteolysis-mass spectrometry (LiP-MS) to screen for structure-specific PPIs by probing for protease susceptibility changes of proteinsin cellular extracts upon treatment with specific structural states of a protein. We first demonstrated that LiP-MS detects well-characterized PPIs, including antibody-target protein interactions and interactions with membrane proteins, and that it pinpoints interfaces, including epitopes. We then applied the approach to study conformation-specific interactors of the Parkinson's disease hallmark protein alpha-synuclein (aSyn). We identified known interactors of aSyn monomer and amyloid fibrils and provide a resource of novel putative conformation-specific aSyn interactors for validation in further studies. We also used our approach on GDP- and GTP-bound forms of two Rab GTPases, showing detection of differential candidate interactors of conformationally similar proteins. This approach is applicable to screen for structure-specific interactomes of any protein, including posttranslationally modified and unmodified, or metabolite-bound and unbound protein states.

Combinatorial Quantification of Multi-Features of Coda Waves in Temperature-Affected Concrete Beams.

Coda waves are highly sensitive to changes in medium properties and can serve as a tool for structural health monitoring (SHM). However, high sensitivity also makes them susceptible to noise, leading to excessive dispersion of monitoring results. In this paper, a coda wave multi-feature extraction method is proposed, in which three parameters, the time shift, the time stretch, and the amplitude variation of the wave trains within the time window, are totally derived. These three parameters are each mapped to the temperature variations of concrete beams, and then combined together with their optimal weight coefficients to give a best-fitted temperature-multi-parameter relationship that has the smallest errors. Coda wave signals were collected from an ultrasonic experiment on concrete beams within an environmental temperature range of 14 °C~21 °C to verify the effectiveness of the proposed method. The results indicate that the combination of multi-features derived from coda wave signals to quantify the medium temperature is feasible. Compared to the relationship established by a single parameter, the goodness-of-fit is improved. During identification, the method effectively reduces the dispersion of identification errors and mitigates the impact of noise interference on structural state assessment. Both the identification accuracy and stability are improved by more than 50%, and the order of magnitude of the identification accuracy is improved from 1 °C to 0.1 °C.

Changes in the structural and functional state of the thyroid gland of small mammals when exposed to low-intensity chronic radiation.

The study gives a morphofunctional assessment of the state of the thyroid gland of tundra voles (Microtus oeconomus Pall.) in conditions of an increased radiation background (the Ukhta district of the Komi Republic (Russia) and the 30-km zone of the Chernobyl NPP), as well as in an experiment with chronic external gamma irradiation in the low dose range. The work summarizes the experience of more than 35 years of field and laboratory research. The authors have noted the high sensitivity of the thyroid gland to chronic radiation against the general irradiation of the organism both in natural conditions and in the experiment. The repeatability of the observed effects in voles from natural populations and the comparability of some effects with the morphological changes occurring in animals after exposure to ionizing radiation in the experiment indicates the radiation nature of these effects. The tundra voles living in conditions of increased radiation background have been identified for a greater variety of morphological rearrangements in the thyroid parenchyma than the experimental animals. The complex and ambiguous nature of the thyroid gland responses to radiation exposure indicates the possibility of a significant increase in the risk of negative effects of ionizing radiation in contrast with the expected results of biological effects' extrapolation from high to low doses.

Вибір блокатора ренін-ангіотензин-альдостеронової системи для лікування серцевої недостатності при гострому міокардиті

The aim – to evaluate the effectiveness of sacubitril/valsartan and enalapril in heart failure treatment in patients with acute severe myocarditis with reduced left ventricular ejection fraction based on dynamic analysis of the heart structural and functional changes.Materials and methods. The study is based on the results of examinations of 90 patients with a severe course of acute myocarditis (AM) with reduced ejection fraction (EF) of the left ventricle (LV) – ≤40 %. The patients were divided into two groups: the 1st group included 48 patients who were treated with an angiotensin-converting enzyme (ACE) inhibitor – enalapril as part of heart failure (HF) therapy; the 2nd group included 42 patients with AM who received the sacubitril/valsartan combination instead of enalapril in the complex therapy of HF. All patients underwent a 6-minute walk test, echocardiography (EchoCG) with the speckle-tracking method, and cardiac magnetic resonance imaging (CMR). Examinations were carried out three times: in the 1st month from the onset of AM symptoms before the appointment of drug therapy, after 6 and 12 months of observation. Part of the patients from the 1st group, namely 25 patients (52.1 %) in whom the use of ACE inhibitors proved to be ineffective after six months, was transferred to the combination of sacubitril/valsartan (group 1A).Results and discussion. After six months of treatment, compared to the 1st group, the patients of the 2nd group were distinguished by better indicators of the structural and functional state of the heart, which characterise the contractility and volume of the LV – the values of LV EF and LV longitudinal global systolic strain (LGSS) were higher by 13,7 and 26.2 % respectively, LV end-diastolic volume index (EDVi) was 13.2% lower, as well as a 21.7 % lower number of LV segments in which delayed contrast was detected on cardiac MRI. After six months of taking the sacubitril/valsartan combination in 1A group patients, an improvement in the structural and functional state of the heart was also achieved: the values of LVEF and LGSS increased by 19.2 % and 27.9 %, respectively, and LV EDVi decreased by 19.0 %; the number of LV segments in which delayed enhancement was determined on cardiac MRI decreased by 30.7 %. With the help of regression analysis, it was established the presence of a set of factors that determine the priority of prescribing the sacubitril/valsartan combination as initial therapy in patients with severe myocarditis: presence of reduced LVEF – ≤40 %; pronounced decrease in longitudinal and circular global LV strain – ≤8.5 and ≤9.0 %, respectively; pronounced dilatation of the LV – EDVi ≥102 ml/m2; presence of III or higher HF functional class; presence of delayed enhancement in ≥ 5,0 LV segments according to cardiac MRI data.Conclusions. In patients with a severe course of myocarditis, the sacubitril/valsartan combination prescribed as initial therapy showed higher effectiveness compared to ACE inhibitors in terms of improving contractility and reducing LV dilatation, as well as improving the functional class of heart failure. A complex of factors has been established that prove the expediency of prescribing the sacubitril/valsartan combination as initial therapy for heart failure in patients with acute myocarditis.

An appraisal of the LQI as an approach to setting target reliabilities in ISO 2394:2015

The idea of coupling economics and safety into one optimization exercise, and hence deriving target reliabilities explicitly from socio-economic consequences of limit state violation, appeared in the JCSS Probabilistic Model Code around the turn of the century; the effort culminated in the form of a Life Quality Index (LQI)-based marginal lifesaving costs (MLSC) methodology in ISO 2394:2015 for determining maximum acceptable failure probabilities, pT, in life safety limit states for civil engineering structures across all nations. Unfortunately, while the methodology does yield adequate levels of safety when applied to structures in the developed countries, the recommended values of pT turn out to be one to two orders of magnitude higher, and unacceptable to every known standard in the world including its own earlier edition (ISO 2394:1998) when applied to structures in the developing world (exemplified by India) with identical functions and expected fatalities. This arises from two shortcomings: (1) an MLSC approach is generally unable to provide an independent constraint on monetary optimization, and (2) the LQI-based measure of MLSC constraint is strongly dependent on a country’s per capita GDP (g) and the resultant pT is effectively governed by the reciprocal of g. This paper recommends continuing with the absolute − not marginal − consequences of violating life safety limit states, and setting constraints on monetary optimization that are consistent with fatality risks from engineering activities more universally accepted to be safe.

Physical properties of the XScH3 (X: Ca, and Mg) perovskite hydrides and their hydrogen storage applications

We conducted a comprehensive investigation into the structural, mechanical, electronic, magnetic, thermodynamic, optical, and hydrogen storage properties of the novel XScH3 (X: Ca and Mg) perovskite hydrides by using density functional theory (DFT). Our calculations of the cohesive energy and elastic constants demonstrated that XScH3 compounds exhibit both thermal and mechanical stability. The metallic nature of current materials is based on the investigation of the electronic band structure and total density states. The analysis of Pugh’s ratio (B/G) indicated that these hydrides were ductile materials. Furthermore, it was found that their bonding type was primarily ionic. These substances have been classified as conductors with antiferromagnetic qualities in terms of their magnetic properties. Furthermore, these materials exhibited promising effects on optical properties such as conductivity, absorption, dielectric function, and refractive index. Our predictions revealed that CaScH3 was found to be optically superior hydride. The dynamic stability of these crystals was assessed by analyzing their phonon dispersion curves and by molecular dynamics simulations. Additionally, we studied their thermal properties, including heat capacity, entropy, energy, and free energy, as functions of temperature. Furthermore, our study investigated the hydrogen storage capacity of XScH3 compounds, with CaScH3 and MgScH3, demonstrating hydrogen storage capacities of 3.43 wt.% and 4.18 wt.%, respectively. This study marks the first exploration of XScH3 perovskite hydrides and offers new options for hydrogen storage materials.

Navigating the depths: Experimental study on the influence of ground fissures on metro shield tunnels considering different intersection angles

Ground fissures are a typical slowly changing geological hazard that poses great safety risks to metro shield tunnels crossing ground fissures. To thoroughly analyze the deformation and failure of shield tunnels under the action of ground fissures with different intersection angles, this study reviews the existing research and carries out model tests on metro shield tunnels crossing ground fissures considering different intersection angles. Based on the experimental results and numerical simulations under multiple conditions, the deformation and failure characteristics of shield tunnels are systematically analyzed for the first time, which confirms that the activity of ground fissures can lead to a series of problems, including segment dislocation, lining cracking, structural elliptical deformation, bolt yield, joint opening and closing, void areas at the tunnel bottom in the hanging wall and tunnel top in the footwall, as well as resulting waterproof failure and internal gauge changes. In addition, as the intersection angle between tunnel and ground fissure increases, the failure mode of the structure gradually transitions from torsional failure to shear failure, with a decrease in the number of segment rings under bias pressure and an increase in the number of segment rings under shear effect. Based on the deformation characteristics, failure positions, and the changes of structural state of shield tunnels, some reflections on countermeasures are discussed, which can provide guidance for the design and maintenance of metro projects in ground fissure sites.