Search

On 23 March 2018, an event of magnitude ML 3.9 occurred about 10 km from the town of Ostuni, in the Adriatic offshore. It was the most energetic earthquake in South–Central Apulia ever recorded instrumentally. On 13 February 2019, in the same area, a second ML 3.3 event was recorded. The analysis of the 2018 event shows that the ambiguity of the solution of the fault plane reported by INGV (Istituto Nazionale di Geofisica e Vulcanologia) on the Italian National Earthquake Centre website can be solved considering existing seismic profiles, exploration well logs and the Quaternary activity of faults in the epicentral area. A seismogenic source was identified in the rupture of a small portion of a 40 km length structure with strike NW-SE, dipping at a high angle toward the south. In this work, we have relocated the recent earthquakes by using the seismic stations managed by the University of Bari (UniBa), one of which is quite close to the event's epicenter (about 20 km), together with data coming from the RSN (Rete Sismica Nazionale). Furthermore, we have determined the focal mechanism of some events, with implications on stress field of the area. Our results show right-lateral transtensional kinematics of the seismogenic faults along approximately E-W striking planes, with a tension, T, with a trend of about 60° (NE-SW direction) and a plunge of 20°. Finally, we have tried to correlate the location of the four best constrained earthquakes with their seismogenic structures. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Geodesy & Geodynamics (1671-5942) is the property of Editorial Board Journal of Geodesy & Geodynamics and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The Himalaya–Tibet region represents a complex region of active deformation related to the ongoing India–Eurasia convergence process. To provide additional constraints on the active processes shaping this region, we used a comprehensive dataset of GNSS and focal mechanisms data and derived crustal strain and stress fields. The results allow the detection of features such as the arc-parallel extension along the Himalayan Arc and the coexistence of strike-slip and normal faulting across Tibet. We discuss our findings concerning the relevant geodynamic models proposed in the literature. While earlier studies largely emphasized the role of either compressional or extensional processes, our findings suggest a more complex interaction between them. In general, our study highlights the critical role of both surface and deep processes in shaping the geodynamic processes. The alignment between tectonic stress and strain rate patterns indicates that the crust is highly elastic and influenced by present-day tectonics. Stress and strain orientations show a clockwise rotation at 31°N, reflecting deep control by the underthrusted Indian Plate. South of this boundary, compression is driven by basal drag from the underthrusting Indian Plate, while northward, escape tectonics dominate, resulting in eastward movement of the Tibetan Plateau. Localized stretching along the Himalaya is likely driven by the oblique convergence resulting from the India–Eurasia collision generating a transtensional regime over the Main Himalayan Thrust. In Tibet, stress variations appear mainly related to changes in the vertical axis, driven by topographically induced stresses linked to the uniform elevation of the plateau. From a broader perspective, these findings improve the understanding of driving crustal forces in the Himalaya–Tibet region and provide insights into how large-scale geodynamics drives surface deformation. Additionally, they contribute to the ongoing debate regarding the applicability of the stress–strain comparison and offer a more comprehensive framework for future research in similar tectonic settings worldwide. [ABSTRACT FROM AUTHOR]

Ultrasonic vibration-assisted grinding (UVAG) enhances surface integrity in machined parts, especially in achieving greater compressive residual stress. Typically, the calculation of residual stresses in UVAG relies on generic finite element software that is not optimized for this purpose, suffering from cumbersome modeling and inefficient calculations. This paper introduces a numerical-analytical hybrid model tailored to predict residual stresses in UVAG. The model independently calculates mechanical and thermal stress fields using contact mechanics and finite difference methods. It employs Hertz's contact theory and Timoshenko's thermoelastic theory to establish a correlation between mechanical and thermal loads and the internal stresses in the workpiece. The residual stress field is then determined by considering the thermal-mechanical coupling effects inherent in UVAG. Experiments conducted on 12Cr2Ni4A alloy steel validate the model, with a maximum deviation of 10.5% between predicted and measured residual stresses. Further analysis shows that the presented method has a significant computational efficiency advantage over the simulation method that uses generic finite element software. The work confirms the accuracy and efficiency of the proposed model, offering a novel approach for predicting residual stress in UVAG. [ABSTRACT FROM AUTHOR]

Fe90 alloy has a high weld hardness, good toughness, and high oxidation resistance, and is often used as a cladding material to repair the surfaces of 42CrMo steel structures of large shearer picks. The influence of the laser cladding processing parameters on the microstructure, properties, and formation mechanism of Fe90 alloy layers on the surface of 42CrMo steel was studied. Simulations were conducted to investigate how these processing parameters affect the temperature field and internal stress of the cladding layer. A complex nonlinear relationship between variables and residual stresses in the laser cladding layers obtained by additive manufacturing was fitted. An optimization model for residual stress in the cladding layer was established and an improved genetic algorithm was used for optimization, which resulted in a 15.88% reduction in residual stress. The results show that optimizing the processing parameters increased the amount of Ni-Cr-Fe solid solution in the cladding layer, enhancing its strength and corrosion resistance. The amount of residual stresses rose with increases in laser power, but at higher powers, increasing the scanning speed and spot diameter reduced stresses. At lower powers, the amount of residual stresses initially increased and then decreased with the scanning speed, with more significant changes occurring with larger spot diameters. Analyzing temperature and residual stress changes allowed us to improve the cladding layer quality, providing a theoretical basis for laser cladding on 42CrMo. [ABSTRACT FROM AUTHOR]

Abstract A prolonged earthquake swarm has persisted since June 2018 in northeastern Noto Peninsula (central Japan), with activity focused into distinct southern, western, northern, and eastern clusters. To explore the role of fluids in the occurrence of this swarm, we analyzed the focal mechanisms of the earthquakes occurring from 1 January 2018 to 30 November 2022 and performed stress tensor inversions. The western, northern, and eastern clusters were dominated by a reverse fault-type mechanism with a horizontal P-axis oriented NW–SE. One of the nodal planes of those mechanisms aligns closely with the precisely relocated hypocenter distribution. The stress fields in these three clusters, as determined by stress tensor inversion, have maximum principal stresses oriented horizontally in the NW–SE direction and minimum principal stresses oriented vertically, aligning with the regional stress field. From these focal mechanisms and this stress field, we derived small misfit angles and large slip tendencies. These findings suggest that, in these three clusters, fluids diffused into faults largely aligned with the regional stress field, resulting in earthquakes with compatible focal mechanisms. Conversely, normal and strike-slip fault-type focal mechanisms, which are unfavorable to the regional stress field, dominated in the southern cluster. The estimated stress fields, deviating from the regional stress field, have maximum principal stresses closer to vertical and minimum principal stress oriented horizontally in the ENE–WSW direction. For earthquakes deeper than 15 km, this local stress field results in relatively larger misfit angles and lower slip tendency than the other clusters. These results suggest that those earthquakes in the southern cluster occurred on misoriented fault planes due to elevated pore fluid pressures. These findings provide strong evidence of the ascent of high-pore-pressure fluids from depth in the southern cluster and their subsequent diffusion into a southeast-dipping fault zone. Graphical Abstract

Abstract Background Faulting induced by earthquakes and its analysis are of great importance for areas with high probability of earthquakes. However, there has been no particularly effective methods to evaluate the damage and applicable solutions for recovery. In this paper, the damage from Türkiye earthquakes is investigated by authors, which has important theoretical significance and practical value. On 6 February, 2023, two successive earthquakes with magnitudes (Mw) of 7.8 (called Pazarcık earthquake) and 7.6 (Ekinözü earthquake) occurred in the south-eastern part of Türkiye. The total length of the surface ruptures was more than 500 km long and resulted in striations reflecting the sinistral faulting and extensive ground deformations. In this study, the authors present the outcomes of the investigations on the surface ruptures, their characteristics, stress field associated with both earthquakes, shear strength property of fault segments and the damaging effects on various structures and made some recommendations with the purpose of how to build structures in active fault zones and decrease the negative effects of faulting on structures. Results Besides summarizing the main characteristics of the world-shaking Kahramanmaraş earthquake doublet in southeast Türkiye in 2023, this study described the main features of the surface ruptures, their relation to the inferred crustal stresses in Türkiye, and the damaging effects on the major engineering structures. The observations and inferences are of great significance for understanding the causes of earthquakes and future seismic risk assessment. Various laboratory experiments were performed on the samples of fault gouge gathered from the sites of surface ruptures and these experimental results provided very valuable quantitative information on the constitutive models of the fault zones. The observations clearly showed that it is almost impossible to prevent damage on structures due to surface ruptures, if certain engineering principles such as increasing higher ductility, lowering gravitational center and/or the implementations of raft foundations are followed. Conclusions The stress state inferences obtained from the striation of the fault surface ruptures as well as from the focal plane solutions are expected to be useful to evaluate the regional stress state of the earthquake region. Assessments indicated that the stress states in Arabian plate and Anadolu platelet are different from each other. However, in-situ direct stress measurement techniques would be quite useful to validate the stress state inferred in this study. The laboratory experiments on samples gathered from the fault outcrops of the earthquakes using direct shear tests, stick-slip tests as well as conventional tensile, compressive and triaxial tests provided the quantitative values for the parameters of constitutive laws for fault zones, which can be utilized in the numerical simulation of earthquakes. If a fault break happens to be just passing underneath the structures, it is almost impossible for mankind to prevent the damage to structures. However, the authors made some recommendations to reduce the negative effects of fault ruptures on structures. These recommendations are such that the structures should be built as ductile and redundant structures with lower center of gravity and raft foundations. Dam construction should be on active faults should be avoided. If they are to be built for whatever reason, they should be of rock-fill type. As tubular structures and tunnels would be generally subjected forced displacement field, it is recommended to utilize flexible joints, segmented and enlargement to deal such displacement fields.

Abstract The thick and hard roof (THR) is a significant factor that induces rock burst incidents. Traditional deep-hole blasting methods struggle to effectively relieve pressure for the high-level THR on a large scale. Although the horizontal staged hydraulic fracturing technology can crack high-level rock stratas, its impact on roof fracture still needs to be clarified, and there need to be more effective methods to evaluate its pressure relief effect. This paper conducted a comparative engineering test of local hydraulic fracturing pressure relief and load reduction on the working face to address this gap. The key layer theory and mine earthquake distribution were used to identify potential hazards of rock strata and the fracturing strata. Revealed the spatial and temporal evolution rules of microseisms induced by mining work, the failure mechanism of high-energy mine earthquakes, the evolution characteristics of source mechanical parameters, and the evolution characteristics of the stope stress field. The results indicate that after fracturing microseisms during mining presented exhibit a uniform distribution of high frequency and low energy. The fracture fragmentation of the roof rock was reduced, and the range of mining disturbance was minimized. High-energy mine earthquakes induced by mining are transferred to the goaf. Simultaneously, the corner frequency and stress decrease while the rupture radius and the shear component of the failure mechanism increase. The integrity of the THR is compromised, and fracture propagates and slips along the pre-crack. The roof of the working face experiences localized pressure, with decreased periodicity and intensity, reducing the overall static load level of the coal seam under the fracturing area. The research findings serve as a valuable reference for further investigations into the mechanism and risk assessment of hydraulic fracturing in preventing and controlling rock burst.

Objective The Sikeshu Sag of the southern Junggar Basin is tectonically located in the western thrust belt of the North Tianshan Mountains. The basin has undergone multiple stages and multidirectional tectonic movements since the Palaeozoic. Clarifying the structural characteristics and evolutionary process of the structural system in the study area is critical for petroleum exploration and development in such petroliferous basins. Methods Utilizing the seismic data interpretation and the outcrop geological investigation of the Sikeshu Sag, spatial-temporal variations in the structural patterns and stress fields were revealed, and a tectonic evolution model was established. Results This study indicates that the compressional inversion and strike-slip structures were widely developed in the deep-buried layers of the Sikeshu Sag, but the thrust and decollement structures were more prevail in the shallow layers of the Sikeshu Sag. According to the structural style, the Sikeshu Sag can be divided into the southern compressional fault-fold belt, central strike-slip compressive-torsional belt, and northern uplift belt. The Sikeshu Sag experienced two periods of strong tectonic uplift, corresponding to the peak period of two stages of fault activity. The tectonic environment and stress field conditions underwent multiple changes: the NNW-SSE extension driven by the back-arc rifting during the late Carboniferous to early-middle Permian, the rift-depression transition triggered by the NNW-SSE extrusion of the Zaire orogenic movement during the late Permian to Triassic, the regional depression induced by the NNW-SSE extrusion of the peripheral orogenic belt and Chepaizi uplift during the late Jurassic to Palaeogene, and the reactivation of foreland caused by NS extrusion of North Tianshan Mountains during the Neogene. Conclusion This study explores the tectonic evolution of the Sikeshu Sag under multiphase stress fields, which favors the better understanding of the overall tectonic pattern changes in similar petroliferous basins and provides new insights for the next steps of petroleum exploration in the study area.

Abstract Geothermal energy has gained wide attention as a renewable alternative for mitigating greenhouse gas emissions. The advancements in enhanced geothermal system technology have enabled the exploitation of previously inaccessible geothermal resources. However, the extraction of geothermal energy from deep reservoirs poses many challenges due to high‐temperature and high‐geostress conditions. These factors can significantly impact the surrounding rock and its fracture formation. A comprehensive understanding of the thermal–hydraulic–mechanical (THM) coupling effect is crucial to the safe and efficient exploitation of geothermal resources. This study presented a THM coupling numerical model for the geothermal reservoir of the Yangbajing geothermal system. This proposed model investigated the geothermal exploitation performance and the stress distribution within the reservoir under various combinations of geothermal wells and mass flow rates. The geothermal system performance was evaluated by the criteria of outlet temperature and geothermal productivity. The results indicate that the longer distance between wells can increase the outlet temperature of production wells and improve extraction efficiency in the short term. In contrast, the shorter distance between wells can reduce the heat exchange area and thus mitigate the impact on the reservoir stress. A larger mass flow rate is conducive to the production capacity enhancement of the geothermal system and, in turn causes a wider range of stress disturbance. These findings provide valuable insights into the optimization of geothermal energy extraction while considering reservoir safety and long‐term sustainability. This study deepens the understanding of the THM coupling effects in geothermal systems and provides an efficient and environmentally friendly strategy for a geothermal energy system.

A prolonged earthquake swarm has persisted since June 2018 in northeastern Noto Peninsula (central Japan), with activity focused into distinct southern, western, northern, and eastern clusters. To explore the role of fluids in the occurrence of this swarm, we analyzed the focal mechanisms of the earthquakes occurring from 1 January 2018 to 30 November 2022 and performed stress tensor inversions. The western, northern, and eastern clusters were dominated by a reverse fault-type mechanism with a horizontal P-axis oriented NW–SE. One of the nodal planes of those mechanisms aligns closely with the precisely relocated hypocenter distribution. The stress fields in these three clusters, as determined by stress tensor inversion, have maximum principal stresses oriented horizontally in the NW–SE direction and minimum principal stresses oriented vertically, aligning with the regional stress field. From these focal mechanisms and this stress field, we derived small misfit angles and large slip tendencies. These findings suggest that, in these three clusters, fluids diffused into faults largely aligned with the regional stress field, resulting in earthquakes with compatible focal mechanisms. Conversely, normal and strike-slip fault-type focal mechanisms, which are unfavorable to the regional stress field, dominated in the southern cluster. The estimated stress fields, deviating from the regional stress field, have maximum principal stresses closer to vertical and minimum principal stress oriented horizontally in the ENE–WSW direction. For earthquakes deeper than 15 km, this local stress field results in relatively larger misfit angles and lower slip tendency than the other clusters. These results suggest that those earthquakes in the southern cluster occurred on misoriented fault planes due to elevated pore fluid pressures. These findings provide strong evidence of the ascent of high-pore-pressure fluids from depth in the southern cluster and their subsequent diffusion into a southeast-dipping fault zone. [ABSTRACT FROM AUTHOR]

Background: Faulting induced by earthquakes and its analysis are of great importance for areas with high probability of earthquakes. However, there has been no particularly effective methods to evaluate the damage and applicable solutions for recovery. In this paper, the damage from Türkiye earthquakes is investigated by authors, which has important theoretical significance and practical value. On 6 February, 2023, two successive earthquakes with magnitudes (Mw) of 7.8 (called Pazarcık earthquake) and 7.6 (Ekinözü earthquake) occurred in the south-eastern part of Türkiye. The total length of the surface ruptures was more than 500 km long and resulted in striations reflecting the sinistral faulting and extensive ground deformations. In this study, the authors present the outcomes of the investigations on the surface ruptures, their characteristics, stress field associated with both earthquakes, shear strength property of fault segments and the damaging effects on various structures and made some recommendations with the purpose of how to build structures in active fault zones and decrease the negative effects of faulting on structures. Results: Besides summarizing the main characteristics of the world-shaking Kahramanmaraş earthquake doublet in southeast Türkiye in 2023, this study described the main features of the surface ruptures, their relation to the inferred crustal stresses in Türkiye, and the damaging effects on the major engineering structures. The observations and inferences are of great significance for understanding the causes of earthquakes and future seismic risk assessment. Various laboratory experiments were performed on the samples of fault gouge gathered from the sites of surface ruptures and these experimental results provided very valuable quantitative information on the constitutive models of the fault zones. The observations clearly showed that it is almost impossible to prevent damage on structures due to surface ruptures, if certain engineering principles such as increasing higher ductility, lowering gravitational center and/or the implementations of raft foundations are followed. Conclusions: The stress state inferences obtained from the striation of the fault surface ruptures as well as from the focal plane solutions are expected to be useful to evaluate the regional stress state of the earthquake region. Assessments indicated that the stress states in Arabian plate and Anadolu platelet are different from each other. However, in-situ direct stress measurement techniques would be quite useful to validate the stress state inferred in this study. The laboratory experiments on samples gathered from the fault outcrops of the earthquakes using direct shear tests, stick-slip tests as well as conventional tensile, compressive and triaxial tests provided the quantitative values for the parameters of constitutive laws for fault zones, which can be utilized in the numerical simulation of earthquakes. If a fault break happens to be just passing underneath the structures, it is almost impossible for mankind to prevent the damage to structures. However, the authors made some recommendations to reduce the negative effects of fault ruptures on structures. These recommendations are such that the structures should be built as ductile and redundant structures with lower center of gravity and raft foundations. Dam construction should be on active faults should be avoided. If they are to be built for whatever reason, they should be of rock-fill type. As tubular structures and tunnels would be generally subjected forced displacement field, it is recommended to utilize flexible joints, segmented and enlargement to deal such displacement fields. [ABSTRACT FROM AUTHOR]

We evaluated the spatiotemporal evolution of microseismic (MS) sources generated by multiple fracturing of a hard and thick Jurassic rock stratum in the 93upper24 working face of the Nantun coal mine, China. Moment tensor inversion, stress field analysis, velocity tomography, and stress inversion were used to reveal individual rupture types and the failure process of the hard rock stratum in the working face during the mining operation. We simulated the change in Coulomb stress before and after the occurrence of mining-induced tremors, and analyzed its impact on the stability of the surrounding rock close to the working face. Our results demonstrate that the static Coulomb stress change computation is an efficient tool to predict the evolution of subsequent MS events patterns. The outcome of this work allows to identify and better understand the failure mechanism within a hard and thick Jurassic rock stratum during the mining operation, and can be an interesting approach in improving mine safety in similar environments. Highlights Induced microseismic events (evolution of hypocenters, energy, and source types of events) are used to characterize the failure process in a hard–thick Jurassic rock stratum during mining operations. Both the near-field stress evolution during mining (secondary stresses) and the far-field regional stress regime (primary stresses) plays a role in the fracturing and failure process of the Jurassic rock stratum. An interaction mechanism of the 3upperF271 fault instability (tectonic stresses) and the rock mass failure within the working face is identified and quantified via Coulomb stress analysis. [ABSTRACT FROM AUTHOR]

The impact of fractures on the hydro-mechanical behavior of fractured rock masses is analyzed by means of equivalent Biot (α ¯) and Skempton (B ¯) coefficients. We assume the derivation proposed by De Simone et al. (Rock Mech Rock Eng 56:8907–8925, 2023), in which the equivalent coefficients depend on the combination of fracture size, orientation and mechanical properties, with the mechanical properties of the intact rock. We extend this theory to incorporate more complex and realistic assumptions on fractures, such as the dependence of aperture and normal stiffness on size and confining stress. Under this setting, we explore the range of variability of the two equivalent coefficients with respect to the stochastic distribution of fracture size and orientation in the rock mass, as well as to depth and stress faulting regime. We find that, although α ¯ and B ¯ increase with fracture density, they are larger if the network is populated by a few large fractures than if populated by many small fractures because large fracture are more compliant. Orientation and depth also greatly impact the coefficients. Fractures oriented such that the applied normal stress is maximized, lead to larger equivalent Skempton coefficients and smaller equivalent Biot coefficient. However, the initial confining stress maximizes both coefficients when fractures are shallow and parallel to the maximum principal stress. Therefore, fracture orientation may differently impact the equivalent coefficients depending on the initial and applied stress tensors. Overall, fracture contribution is larger in shallow rocks containing large fractures that are oriented parallel to the largest principal initial stress and normal to the applied stress. Highlights: Fracture network characteristics strongly impact the equivalent Biot and Skempton coefficients of fractured rocks The coefficients increase with fracture density and porosity of the fractured portion Fracture contribution is larger in systems containing large fractures oriented parallel to the largest principal initial stress and normal to the applied stress. [ABSTRACT FROM AUTHOR]

In order to determine the reasonable parameters of high-gas and extra-thick coal seam drainage, considering the factors of the coal seam metamorphic degree, stress condition, gas occurrence state, and permeability dynamic change, the gas desorption, diffusion, and transport process of coal seam gas are analyzed. A secondary distribution model of coal around the borehole, a porosity variation model of coal around the borehole, a stress–seepage coupling model, a pore flow model of the pressure-driven transition flow zone, and a free molecular flow zone are established. Taking the gas drainage of Zhangcun Coal Mine of Lu'an Group as the research object, the influence of drilling hole diameter, coal seam permeability, gas original pressure, and other factors on the control range of coal seam drainage drilling is simulated by ANSYS Fluent 6.3.26. The results show that secondary stress distribution occurs in the coal seam drill hole under the action of lead stress, which leads to the change in porosity; the seepage zone, transition zone, molecular flow zone, and original rock stress zone are presented around the drill hole; and the range of influence of the drill hole is mainly based on the seepage zone and the transition zone, supplemented by the molecular flow zone. The control range of the drill hole is in a positive proportional relationship to the diameter of the drill hole, the porosity of the coal seam, and the original pressure of the gas. [ABSTRACT FROM AUTHOR]

Enhancing the lifetime of perovskite solar cells (PSCs) is one of the essential challenges for their industrialization. Although the external encapsulation protects the perovskite device from the erosion of moisture and oxygen under various harsh conditions. However, the perovskite devices still undergo static and dynamic thermal stress during thermal and thermal cycling aging, respectively, resulting in irreversible damage to the morphology, component, and phase of stacked materials. Herein, the viscoelastic polymer polyvinyl butyral (PVB) material is designed onto the surface of perovskite films to form flexible interface encapsulation. After PVB interface encapsulation, the surface modulus of perovskite films decreases by nearly 50%, and the interface stress range under the dynamic temperature field (−40 to 85 °C) drops from −42.5 to 64.8 MPa to −14.8 to 5.0 MPa. Besides, PVB forms chemical interactions with FA+ cations and Pb2+, and the macroscopic residual stress is regulated and defects are reduced of the PVB encapsulated perovskite film. As a result, the optimized device's efficiency increases from 22.21% to 23.11%. Additionally, after 1500 h of thermal treatment (85 °C), 1000 h of damp heat test (85 °C & 85% RH), and 250 cycles of thermal cycling test (−40 to 85 °C), the devices maintain 92.6%, 85.8%, and 96.1% of their initial efficiencies, respectively. [ABSTRACT FROM AUTHOR]

This study addresses the necessity for a more profound comprehension of the mechanical behavior and fracture mechanisms of tree branches during impact pruning. The methodologies of the research are to develop a failure model of impact-cutting mechanics and a tool–branch interaction model using the finite element method (FEM). The validation of the model was conducted through the measurement of cutting forces and cross-sectional morphology in the field. A comparative analysis between experimental and simulation data revealed an average relative error below 15% for cutting force and below 10% for the cross-sectional ratio, thereby confirming the accuracy of the model. The findings indicate the presence of plastic deformation within the cutting zone, with elastic deformation prevailing in the surrounding region. As the branch approaches the yield point, the phenomenon of plastic deformation intensifies, resulting in a notable increase in internal energy demands, particularly in larger branches. The optimal pruning diameter was identified as 15 mm. An increase in cutting velocity raises the peak cutting force by 460.9 N per m/s, while a 1° increase in the blade wedge angle adds 34.9 N. A reduction in normal stress by increasing the tool back angle improves energy efficiency. This study provides insights to optimize pruning practices, enhancing efficiency and precision. [ABSTRACT FROM AUTHOR]

With the increase of coal mining depth, roadway stability has become an important research topic in safe and efficient mining of coal mines. The traditional methods of the room and pillar mining (RPM) and the gob-side entry retained by filling (GERF) withstand the pressure of roof by coal pillars and dense roadside supports, which leads to the problem of stress concentration. Recently, an innovative gob-side entry retained by roof cutting (GERRC) technology was been widely used in China's coal production. There are some differences in the stress field in different mining methods. By means of theoretical analysis, numerical simulation and field test, this study explored the distribution characteristics of stress field of three mining methods. The results indicate that the GERRC method cuts off the connection between the roadway roof and the goaf roof, changes the movement of the overlying strata, and reduces the stress of the surrounding rock of the roadway, which belongs to the active pressure-relief technology. The RPM and GERF methods do not change the structure of the surrounding rock, which belongs to the passive pressure-resistance technology, and the surrounding rock of the roadway is significantly affected by the pressure. At the same time, numerical simulation results indicate that the maximum stress in the GERRC method is reduced by 18.1% compared to the RPM method and by 16.1% compared to the GERF method, and the stress concentration area is far away from the roadway. Finally, the numerical simulation results and field monitoring data show good agreement, and the deformation of the surrounding rock can be successfully managed by GERRC technology. The research results provide a guide for the application of GERRC technology in deep coal mines. [ABSTRACT FROM AUTHOR]

Most failures of structural components in service are related to the presence of geometric micro-defects in the material that occurred during its processing. In other words, real materials often contain internal defects such as micro-cracks or cavities. During the deformation process, under sufficient load, these internal defects can propagate and, at the same time, new microdefects occur in the area of stress concentration (inclusions, voids, etc.). This phenomenon influences the macroscopic properties of the material, gradually decreasing its mechanical strength. The process of structural deterioration of the material, resulting from the nucleation and growth of micro-defects, is called damage. This paper focuses on the application of a threedimensional finite element method based on a local approach in order to study the effect of nucleation and growth of micro-voids on the failure of polymer materials. A parametric analysis was carried out to study the sensitivity of the fracture parameters of the Gurson-Tvergaard-Needleman (GTN) model in terms of the stress-strain behaviour and ductility of the material in service. The numerical results obtained from those parametric studies were validated by comparing them with the experimental results in terms of stress-strain behaviour. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Geodesy & Geodynamics (1671-5942) is the property of Editorial Board Journal of Geodesy & Geodynamics and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this study, a numerical model for unilateral quasi-static contact between a rigid sphere and an elastic coating has been developed. The contact problem was solved using a numerical procedure based on the FFT technique, considering various coatings with different thicknesses and mechanical properties, implemented through a Matlab code. The model calculates the contact surface deformation and pressure field through a double iteration process. The first iteration solves the contact problem for a given indenter penetration, while the second iteration refines this penetration by minimizing the difference between the fixed and calculated loads. To achieve this, influence coefficients are derived from the elasto-static equations using the Papkovich-Neuber potentials. The study discusses the influence of coating thickness and friction coefficient value on the tribological behavior of the coating. The results indicate that contact pressure increases (ranging from 1.9 to 2.5) as the coating becomes thicker or more rigid (0.02 mm to 0.2 mm). Additionally, the tribological behavior of the coated surface is affected by the coating's thickness, hardness, and friction coefficient value. Importantly, this model demonstrates versatility by being applicable to both smooth and rough surfaces. [ABSTRACT FROM AUTHOR]

A fibre laser was used to weld Q345D/20Mn2 dissimilar steel with and without a Ni60 powder filler. Finite element (FE) simulation of the temperature and stress fields in the laser beam welding (LBW) was conducted COMSOL. Experimental investigation determined the effect of Ni-based powder filled welding on the microstructure, morphology, element content, microhardness and fracture morphology of the weld cross-section. The results show that when the laser power was 2700 W, the scanning speed was 1 mm/s and the out-of-focus amount was 0 mm, the tensile properties of Q345D/20Mn2 steel welds were optimal and deformation was minimal. Under such conditions the depth of the weld pool can reach 2.7 mm and the width 2.8 mm. After the Ni-based powder melts and penetrates the bottom of the base material (BM) along the weld seam, small cytosolic, equiaxed and columnar crystal grains can be observed near the fusion line, and the Ni-based filler powder can achieve a good metallurgical bond with the BM. The location of tensile fracture is at the weld and small tough nests can be observed in the cross-section leading to judgment that the fracture mode is ductile. [ABSTRACT FROM AUTHOR]

Copyright of Metal Working (1674-165X) is the property of Metal Working Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Geodesy & Geodynamics (1671-5942) is the property of Editorial Board Journal of Geodesy & Geodynamics and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Over time, and with the production from the reservoir, the pore pressure of the production layer is decreased in case of lack of a pressure source. Pressure decreases changes stress magnitude and direction directly. The change in the magnitude of stresses can lead to geomechanical changes in the reservoir and the production layers. In case the reservoir's layers are faulted, the decrease in the reservoir's pressure can activate these faults and also change the tensile strength of the wellbore wall for new drilling in the discharged layer. The present study was conducted in one of the reservoirs in the southwest of Iran. In this reservoir, three production layers with various thicknesses were examined, and the probability of reactivation of the faults and tensile strength in the initial state, and after an 1800-pound psi pressure decrease was evaluated. In layer No.1, the value of the stress path was 0.67, which due to being tangent with the critical stress value, would activate the faults in this layer with production and the decrease in the reservoir's pressure. Also Initially, the maximum allowable drilling mud weight for non-failure is 17.81–25.13 PPG. After a pressure reduction of 1800 psi, it changes to 15.07–23.42 PPG. In addition, the most resistant state of the wellbore wall is drilling with an angle of 60 degrees and in the direction of minimum horizontal stress. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Medical Equipment Journal is the property of Chinese Medical Equipment Journal Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The 2021 Yangbi earthquake sequence occurred on the southwestern margin of the Chuandian block in China, which is a typical foreshock-mainshock-aftershock sequence. We investigate source properties of this earthquake sequence with seismic and geodetic data. Focal mechanisms of M ≥ 2.0 events in this earthquake sequence are determined using P wave first-motion polarity plus S/P amplitude ratio data from local short-period and broadband seismic stations. The determined focal mechanisms together with spatial distribution of the earthquake sequence indicate the overall northwest-southeast-trending seismogenic faults with dominant strike-slip motions. We conduct kinematic finite-fault inversion with strong-motion, local broadband seismic, and coseismic InSAR plus GNSS displacement data, finding that the mainshock ruptured a major asperity unilaterally with a rupture length and duration being approximately 15 km and 6.5 s, respectively. The released scalar seismic moment is 1.7 × 1018 Nm, corresponding to a moment magnitude MW 6.1. Besides, stress field inversion results manifest that source area is characterized by a strike-slip stress regime and the local stress field has changed before and after the mainshock. We suggest that rupture initiation, propagation, and arrest of the 2021 Yangbi earthquake sequence may be regulated by the immanent strength and stress heterogeneities of the seismogenic fault.

Purposes The stress on the metro wheel is complicated, which is not only influenced by the wheel-rail coupling force and the contact pressure induced by the axle-wheel interference fit, but also by the thermal load generated during braking. Methods In this paper, a metro wheel with single S-type spoke plate is taken as the research object. The finite element model of the wheel is established in ABAQUS software and the influence of the axle-wheel interference fit is analyzed on the mechanical stress distribution of the wheel under the straight-line load condition. The thermal-mechanical coupling model of the wheel is established at tread braking under the turnout load condition. The direct coupling method is used to study the variation of the temperature and stress fields of the wheel. Effects of mechanical stress and thermal-mechanical coupling stress on the structural strength of the wheel under different wear levels are studied. Findings Results show that the thermal load mainly affects the structure near the tread, while the part near the hub is greatly affected by the interference fit. The maximum difference of coupling stress between the new wheel and the worn-to-limit wheel is up to 69.3 MPa. The coupling stress of the wheel is relatively stable within the diameter range of 820-840 mm, with a float of only 9.1 MPa. Conclusion This study provides scientific reference for the structural design of metro wheels and can give a good guidance for the maintenance work.

To improve the quality of laser cladding， a finite element analysis process was established， focusing on laser power， scanning speed and powder feed rate as the main process parameters， aiming to reduce the research and development cycle and economic costs of optimizing cladding process parameters. By comparing the temperature and stress field simulation of GX4CrNi13-4 martensitic stainless steel laser cladding data with experimental results， the forming quality under different parameters is verified， optimizing the laser cladding process parameters. The results indicate that the adjustment range of laser power should be controlled between 1800 W to 2000 W to avoid substrate penetration and ensure sufficient density； increasing the powder feed rate effectively reduces temperature and residual stress. Among the three process parameters， laser power has the most significant impact on cladding quality. A comprehensive analysis of density and microhardness tests to assess the cladding quality and residual stress distribution under different parameters reveals that the optimal combination of process parameters is a laser power of 1800 W， scanning speed of 10 mm/s， powder feed rate of 10 g/min. The experimental results are consistent with the trends of stress field simulations， further validating the accuracy of the simulation data.

To comprehensively investigate the evolution of the stress field, a three-dimensional thermodynamic model of laser cladding was developed in this paper. By analyzing the physical process and constructing a mathematical model, the temperature transfer and stress distribution were calculated. The simulation examined the evolution and distribution of stress at various scanning speeds, discussing the interplay between the temperature field and the stress field during rapid heating and cooling. Residual stress was measured through X-ray diffraction in experiments, and the crack distribution within the cladding layer was observed. The findings indicated that the stress values calculated from the simulation model aligned well with the experimental results. By combining experimental data, we conducted a qualitative analysis of the distribution of residual stresses and the trends of crack initiation, leading to the proposal of an optimized processing scheme that significantly enhances the quality and reliability of the cladding layer.

Inter-well frac-hit has become an important challenge in the development of unconventional oil and gas resources such as fractured tight sandstone. Due to the presence of hydraulic fracturing fractures, secondary induced fractures, natural fractures, and other seepage media in real formations, the acquisition of stress fields requires the coupling effect of seepage and stress. In this process, there is also stress sensitivity, which leads to unclear dynamic evolution laws of stress fields and increases the difficulty of the staged multi-cluster fracturing of horizontal wells. The use of a multi-stage stress-sensitive horizontal well production stress field prediction model is an effective means of analyzing the influence of natural fracture parameters, main fracture parameters, and multi-stage stress sensitivity coefficients on the stress field. This article considers multi-stage stress sensitivity and, based on fractured sandstone reservoir parameters, establishes a numerical model for the dynamic evolution of the production stress field in horizontal wells with matrix self-supporting fracture-supported fracture–seepage–stress coupling. The influence of various factors on the production stress field is analyzed. The results show that under constant pressure production, for low-permeability reservoirs, multi-stage stress sensitivity has a relatively low impact on reservoir stress, and the amplitude of principal stress change in the entire fracture length direction is only within the range of 0.27%, with no significant change in stress distribution; The parameters of the main fracture have a significant impact on the stress field, with a variation amplitude of within 2.85%. The ability of stress to diffuse from the fracture tip to the surrounding areas is stronger, and the stress concentration area spreads from an elliptical distribution to a semi-circular distribution. The random natural fracture parameters have a significant impact on pore pressure. As the density and angle of the fractures increase, the pore pressure changes within the range of 3.32%, and the diffusion area of pore pressure significantly increases, making it easy to communicate with the reservoir on both sides of the fractures. [ABSTRACT FROM AUTHOR]

This study performed on-site monitoring of the temperatures on the sunny and shady sides of high-altitude bridge piers. Numerical simulation was used to analyze the stress field within the bridge piers at different temperature differences. Radiation-cooling materials on concrete were recommended to regulate the peak temperatures and temperature differences between sunny and shady surfaces of the bridge piers. The results indicated that the temperature difference between the sunny and shady surfaces can be up to 14.81°C at 4100 m above sea level. The larger the temperature difference, the higher the tensile stress on the sunny surface of the pier. Radiation-cooling materials decreased the concrete peak temperature by about 12°C and reduced the temperature difference between sunny and shady surfaces from 6.6 to 1.8°C. This method can effectively manage the temperature field and introduce a new method for controlling temperature differentials on high-altitude bridge piers. The study can fill the gap in the quantitative investigation of the temperature difference and stress on the sunny and shady surfaces of plateau piers. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Materials Engineering / Cailiao Gongcheng is the property of Journal of Materials Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The northern section of the Longxian-Baoji fault zone has a strong degree of locking, but the locking degree of its southern section is less studied. The observation well of a confined aquifer is considered a sensitive "volumetric strain gauge", and the rise or fall of the well water level often reflects the state of regional stress in tension or compression. Fengxiang Well in Shaanxi is located in the central and southern section of the Longxian-Baoji Fault. Based on the analysis of the variation trend of the water level in Fengxiang Well from 2013 to 2023, the porosity of the aquifer, the volume compression coefficient of the solid skeleton, and the volume compression coefficient of the water were calculated for the aquifer of the well, under un-drained conditions, by using sliding fits such as the barometric pressure coefficient and the M2-wave tidal factor. The temporal characteristics of the tectonic stress field around the well were quantitatively analyzed by using the relationship between the water level variation of the well and the vertical stress variation of the aquifer. Based on the GNSS baseline and surface strain variation characteristics within the region, as well as the seismic activity characteristics since 2013, a comprehensive analysis suggests that the stress field variation characteristics in the region can be divided into two stages: 1 From 2013 to 2017, the water level of Fengxiang well decreased, and the vertical stress weakened, showing a tensile environment with low seismic frequency. 2 From 2017 to 2023, the water level of Fengxiang well tended to stabilize, and the vertical stress fluctuated around zero. The tension weakened and gradually transformed into a stage of stress accumulation and enhancement, with a significant increase in the number of earthquakes. Based on the analysis of the water level, vertical stress, GNSS baseline and surface strain, as well as seismic activity characteristics in the Fengxiang well over the past decade, it can be concluded that the central and southern sections of the Longxian Baoji fault zone is in a relatively stable state with weak stress accumulation and small deformation. [ABSTRACT FROM AUTHOR]

We present a study in the southern Puna (26°30′–27°30′S), aiming to explore the late Cenozoic evolution of the deformation and the stress field during its uplift. Through U‐Pb geochronology, structural observations, paleostress analysis, and balanced cross‐sections, we propose an structural evolutionary model over the past 24 million years, separated in four stages: Stage 1, in the late Oligocene to middle Miocene, the region experienced E‐W compression. Stage 2, from middle to late Miocene, a transition from predominant compression to an incipient strike‐slip regime is observed. Stage 3, from late Miocene to early Pliocene, showed a further shift in the stress field, resulting in a combination of a predominant strike‐slip regime, and less predominant compressional regime. Finally, Stage 4, from late Pliocene to Quaternary, featured a dominance of strike‐slip regimes. Our results show that the stress field in each stage is associated with the orogen's internal architecture and its evolution. Vertical stress variations are linked to plateau uplift, creating topographic gradients across the orogen. Horizontal rotations of the principal stress axes are caused mainly by an edge effect resulting from the growth of the plateau while it reaches a critical crustal thickness and elevation. This leads to a transfer of compression from high‐lying areas to lower regions. The southernmost Puna region shows no significant evidence of normal faulting, suggesting it is not undergoing orogenic collapse associated with a regional tensional stress regime. Key Points: We present a structural study in the southern Puna region focused on the late Cenozoic evolution of the tectonic stress fieldThe study emphasizes the link between internal architecture of an orogen, plateau uplift and the stress field during Miocene‐PleistoceneThe southernmost Puna is not undergoing extensional orogenic collapse [ABSTRACT FROM AUTHOR]

Underground coal gasification (UCG) is an efficient method for the conversion of deep coal resources into energy. The scope of this work is to model the subsidence of four gasification cavities with a size of 30 m × 30 m × 15 m, separated by 15 m wide pillars. Two scenarios of gasification sequence are modelled, one with the gasification of cavities 1 and 2 followed by 3 and 4, and the other one with the sequence of cavities 1 and 3, followed by 2 and 4. The results show that the final surface subsidence after gasification of four cavities is 9.8 mm and the gasification sequence has an impact only on the subsidence at the intermediate stage but has no impact on the final subsidence after all four cavities are formed, when only the elasticity regime is considered. Additionally, the maximum surface subsidence for the studied cavities of different sizes ranges from 0.016 mm to 7.14 mm, and the relationship between the subsidence and the cavity volume is approximately linear. Finally, a prediction model of surface subsidence deformation is built up using the elastic plate theory, and the formula of surface deformation at a random point is given. The maximum difference between measured and calculated deformation is 4.6%, demonstrating that the proposed method can be used to predict the ground subsidence induced by UCG. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Civil Engineering Frontiers (JoCEF) is the property of Interdisciplinary Publishing Academia (IPAcademia) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The development and application of laser welding transition layer technology is pivotal for manufacturing high-performance diamond saw blades. Despite its importance, there is a need for more precise modeling to optimize welding parameters and enhance blade performance. This study employs SYSWELD software to simulate the laser welding process, demonstrating high accuracy in predicting the molten pool shape. A cross-scale multi-field coupling model was established using the finite element method, incorporating temperature field, phase transformation, grain morphology, stress field, and fatigue performance. A comprehensive life cycle assessment identified optimal welding parameters. The results indicate that a laser welding speed of 26 mm/s and a power of 1700 W minimize weld stress, reduce the digital volume correlation (DVC) value, and enhance fatigue resistance. Additionally, welding tests confirmed that using 1700 W produced the highest tooth strength of 1200 MPa, validating the simulation results. This study addresses existing gaps in modeling accuracy and parameter optimization, offering a robust framework for improving the performance and reliability of laser-welded diamond saw blades. [ABSTRACT FROM AUTHOR]

For media with inclusions (e.g., precipitates, voids, reinforcements, and others), the difference in lattice parameter and the elastic modulus between the matrix and inclusions cause stress concentration at the interfaces. These stress fields depend on the inclusions' size, shape, and distribution and will respond instantly to the evolving microstructure. This study develops a phase-field model concerningmodulus heterogeneity. The effect of modulus heterogeneity on the growth process and equilibrium state of the α plate in Ti-6Al-4V during precipitation is evaluated. The α precipitate exhibits strong anisotropy in shape upon cooling due to the interplay of the elastic strain and interfacial energy. The calculated orientation of the habit plane using the homogeneous modulus of α phase shows the smallest deviation fromthat of the habit plane observed in the experiment, compared to the case where the homogeneous modulus of β phase is adopted. In addition, the equilibrium volume of α phase within the systemusing homogeneous β modulus exhibits the largest dependency on the applied stresses. The stress fields across the α/β interface are further calculated under the assumption of modulus heterogeneity and compared to those using homogeneous modulus of either α or β phase. This study provides an essential theoretical basis for developing mechanics models concerning systems with heterogeneous structures. [ABSTRACT FROM AUTHOR]

In this work, conventional sintering, hot-pressing sintering, and spark plasma sintering techniques were utilized to simulate the thermal field, thermal-stress field, and thermal-stress-electric field, respectively. The effects of these fields on the microstructure and cation distribution of the (Mg 0.1 Mn 0.1 Co 0.1 Ni 0.2 Ti 0.1 Cu 0.1 Zn 0.2)Fe 2.1 O 4 ferrite (HEF) material were comprehensively analyzed. The results indicate that in the temperature range of 1000–1100 °C, the thermal field provides the driving force for sintering, promotes grain growth (average particle size: 2→7 μm), and increases crystallinity degree. The stress field brings the particles into close contact with each other, facilitates diffusion, and delays grain growth (0.5→5 μm). The electric field reduces grain boundary energy, causes mass transfer, and makes the grains finer (0.5→0.7 μm) and more uniform. Mathematical model analysis reveals that the thermal field is beneficial to the random distribution of cations, which yields an inversion degree (γ) of about 2/3 and increases the configuration entropy of HEF. The stress field leads to lattice distortion, permits ions with larger radius to occupy tetrahedral positions, and changes the cell parameters and oxygen position parameter of HEF. Finally, the interaction between electric field and crystal charges increases the electrostatic field energy, which promotes the formation of positive spinel structure and maximizes the crystal field stability energy. X-ray photoelectron spectra, Raman spectra, and change in lattice constant confirm the rationality of the mathematical model, and can be used to establish the model of the crystal structure under field effects. [ABSTRACT FROM AUTHOR]

The meta-instability experiment provides a theoretical basis for the extraction of precursor information and the study of earthquake prediction. To study the precursor information of earthquakes, the apparent wave velocity ratio of earthquakes with a longitude of E98°–E102° and latitude of N24°–N28° before the Yangbi Ms6.4 earthquake on May 1 to 21, 2021, was calculated based on experiment results of the relationship between seismic wave velocity and stress. Regional gridding was achieved by interpolation, and the gradient of the apparent wave velocity ratio field and its divergence were analyzed. Energy was found to have been released at points (N26.10°, E99.59°) and (N25.73°, E99.87°) as the center, with a connecting line strike of 145°. Energy was absorbed at multiple points along the axis of the line connecting points (N25.81°, E99.59°) and (N26.58°, E100.26°), with a strike of 38°. Precursor information is a characteristic of meta-instability. According to the meta-instable theory, an earthquake will occur near points (N26.10°, E99.59°) or (N25.73°, E99.87°) or on the line connecting them within 0 to 5 days. The rupture length of the fault was about 49.8 km, which, when converted to Ms6.8, is ideal for comparison with the measured Ms6.4 earthquake that had occurred at point (N25.67°, E99.87°). It is believed that this method can provide a reference for the study of precursors of shallow strike-slip earthquakes with a certain number of foreshocks. [ABSTRACT FROM AUTHOR]