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Numerical simulations of the paleostress field during a period of tectonic fracture formation and rock failure criteria are used to quantitatively predict the development and occurrence of tectonic fractures induced by the formation of the SB18 fault zone in the Middle Ordovician Yijianfang Formation of the Shunnan area, Tarim Basin, China. The results of acoustic emission experiments, mechanical property measurements, and tectonic fracture occurrence observations obtained from core descriptions and fullbore formation microimager logs are combined with the Andersonian model of faulting and the finite element method, which is widely used for the numerical simulation of stress fields, to investigate the paleotectonic and in situ stress fields via numerical simulation. The quantitative prediction of the opening pressure and opening sequence of tectonic fractures is based on the occurrence of tectonic fracture, numerical simulation of in situ stresses, and coordinate system conversion. The results show that the width of the fracture zone induced by strike-slip faulting is ~310 m. The degree of fracture development is significantly increased when the Young's modulus, paleostress difference, and paleostress difference coefficient of the rock are elevated. The current horizontal principal stress is positively correlated with the distance from the fault, and the elevated areal density of the secondary faults causes a clockwise deflection of the horizontal stress direction. SSE-striking shear fractures with orientations ranging from 140° to 150° and two sets of tensional fractures with orientations ranging from -40° to -35° and 55° to 60° are preferentially opened in the water injection development stage of the reservoir. As the horizontal stress difference, horizontal stress difference coefficient, and angle between the maximum horizontal principal stress and a fracture decrease, the fracture opening pressure decreases. At the structural highs (burial depths <6225 m) and lows (burial depths >6225 m), the fracture burial depth is positively and negatively correlated with the opening pressure, respectively. Quantitative prediction of tectonic fracture developmental characteristics, opening pressure, and the opening sequence and investigation of the main factors that control their development can help to identify and support opportunities for hydrocarbon exploration and development of fractured carbonate reservoirs. [ABSTRACT FROM AUTHOR]

In order to evaluate the post-earthquake condition of railway bridges, this study develops a method for evaluating the traffic function of railway bridges based on vulnerability. Taking common railway bridges in China as references, 20 four-span simply-supported beam bridges with varying structural parameters were modeled in OpenSees for full-bridge finite element analysis. Seismic timehistory analysis was employed to evaluate both the vulnerability and traffic function of the bridges, clarifying the key factors influencing seismic damage and traffic function. The findings indicated that the longitudinal reinforcement ratio and shear span-to-depth ratio were the core factors affecting seismic damage, with the axial compression ratio also playing a significant role, while the volumetric stirrup ratio served as a secondary factor. To control seismic damage of the bridges, increasing the longitudinal reinforcement ratio and reducing the shear span-to-depth ratio were recommended. A higher reinforcement ratio significantly enhanced traffic capacity, while an increased shear span-to-depth ratio reduced it. Additionally, slight improvements in traffic capacity were observed with increases in the reinforcement ratio and axial compression ratio. The longitudinal reinforcement ratio and shear span-to-depth ratio were the main factors affecting the traffic function of the bridges, while the volumetric stirrup ratio and axial compression ratio were secondary. To ensure optimal traffic capacity, the longitudinal reinforcement ratio should be appropriately increased or the pier shear span-to-depth ratio be reduced, with modest increases in the volumetric stirrup ratio and axial compression ratio. The traffic capacity evaluation method proposed in this study provides an effective tool for assessing bridge functionality and is suitable for post-earthquake assessments. [ABSTRACT FROM AUTHOR]

Rail braces are important components for reinforcing tracks in railway curves and steep slope sections. Field surveys have identified several issues with existing rail brace structures, such as uneven local stiffness, poor adjustability, and multiple types. The uneven stiffness in existing structures causes some fasteners to fail in providing adequate lateral support, leading to significant impacts on tracks and resulting in poor track conditions. Furthermore, poor adjustability leads to gaps between the rail braces and the rail web, causing improper contact. Over time, this can damage both the sleepers and the rails, complicating track maintenance and operations. To meet the demands of heavy-load railways, mixed passenger-freight lines, and other railway applications, a series of elastic rail braces for 50 kg/ m, 60 kg/ m, and 75 kg/ m specialized rails were developed. These braces featured a one-piece design that ensured full contact between the rail braces and the web, increasing the contact area and improving lateral resistance. Elastic rubber or polyurethane materials were embedded (vulcanized) into the sides of the rail brace, preventing hard contact with the rail. The design allowed for slight displacement, maintaining elasticity and reducing the abrasion and damage caused by rail braces pressing against the web. A solid model of elastic rail brace was established using the finite element method to theoretically analyze its stress distribution and determine reasonable technical parameters. In addition, testing methods and technical requirements for assembling the elastic rail braces were developed. Indoor comparative tests were carried out under identical conditions with the type II elastic fastener used in China's railway. The results showed that all indicators met expectations, demonstrating the design's safety and reliability. To further validate its practical applications, field trials were conducted on a small-radius curved track with a radius of 400 m. Observation data indicated that the elastic rail brace effectively resisted the abnormal lateral load on the rails, with minimal track gauge variation rate. The design meets the required standards, ensuring safe train operations, and has significant potential for widespread applications. [ABSTRACT FROM AUTHOR]

High-rise intake towers in high-intensity seismic areas are prone to structural safety problems under vibration. Therefore, effective and low-cost anti-seismic engineering measures must be designed for protection. An intake tower in northwest China was considered the research object, and its natural vibration characteristics and dynamic response were first analyzed using the mode decomposition response spectrum method based on a three-dimensional finite element model. The non-dominated sorting genetic algorithm-II (NSGA-II) was adopted to optimize the anti-seismic scheme combination by comprehensively considering the dynamic tower response and variable project cost. Finally, the rationality of the original intake tower antiseismic design scheme was evaluated according to the obtained optimal solution set, and recommendations for improvement were proposed. The method adopted in this study may provide significant references for designing anti-seismic measures for high-rise structures such as intake towers located in high-intensity earthquake areas. [ABSTRACT FROM AUTHOR]

Background: This study aimed to evaluate the effect of foraminoplasty using large-channel endoscopy during TESSYS on the biomechanics of the lumbar spine. Methods: A complete lumbar spine model, M1, was built using 3D finite elements, and models M2 and M3 were constructed to simulate the intraoperative removal of the superior articular process of L5 using a trephine saw with diameters of 5 mm and 8.5 mm, respectively, and applying normal physiological loads on the different models to simulate six working conditions—anterior flexion, posterior extension, left-right lateral bending, and left-right rotation—to investigate the displacement and facet joint stress change of the surgical segment, and the disc stress change of the surgical and adjacent segments. Results: Compared with the M1 model, the M2 and M3 models showed decreased stress at the L4-5 left FJ and a significant increase in stress at the right FJ in forward flexion. In the M2 and M3 models, the L4-5 FJ stresses were significantly greater in left lateral bending or left rotation than in right lateral bending or right rotation. The right FJ stress in M3 was greater during left rotation than that in M2, and that in M2 was greater than that in M1. The L4-5disc stress in the M3 model was greater during posterior extension than that in the M1 and M2 models. The L4-5disc stress in the M3 model was greater in the right rotation than in the M2 model, and that in the M2 model was greater than that in the M1 model. Conclusion: Foraminoplasty using large-channel endoscopy could increase the stress on the FJ and disc of the surgical segment, which suggested unnecessary and excessive resection should be avoided in PTED to minimize biomechanical disruption. [ABSTRACT FROM AUTHOR]

The project case of Qiwu Bridge using link slab action between simply supported composite spans is introduced. The 60 m-span girder of Qiwu Bridge is the longest and heaviest among the composite girders erected by bridge-erecting machine in China. Qiwu Bridge consists of a series of 3 simply supported spans built with composite girders and connected at the pier supports by a link slab. This solution has both advantages of (1) smooth driving condition and enhancement of durability by removing expansion joints and (2) clear structural behavior as simply supported spans. A finite element model was established to simulate and predict the mechanical response of this semi-continuous solution. Numerical results showed that the removal of the shear connection around the link slab decreased the stress level but also caused a stress mutation. Qiwu Bridge was also monitored by vibrating wire strain gages to follow its actual structural response. From preliminary monitoring data and numerical results, it can be concluded that the proposed construction method and the static scheme is safe for the 60-span composite girder with a large safety margin. Further experimental results will be obtained during the service stage of the bridge to validate the in-service performance of the proposed steel-concrete composite bridge with link slab. [ABSTRACT FROM AUTHOR]

The transverse seismic behavior of a long-span cable-stayed bridge with two inverted Y-shaped reinforced concrete towers is investigated in this study. To accomplish this, a 1/35-scale model of a cable-stayed bridge with a span of 1088 m was designed, constructed, and tested until failure on four shake tables; the test was conducted at Tongji University, China. A site-specific artificial wave was applied in the transverse direction. Moreover, the input peak ground acceleration was increased from 0.1 g to 1.3 g until the test model failed. The transverse displacement, force, rebar strain, and curvature responses of the bridge model are obtained and studied. The test results showed that the transverse displacement response of the tower was significantly affected by high-order modes. This resulted in the maximum seismic displacement of the tower at the middle – upper level of the middle column except for the tower top. The ratio of the transverse seismic forces acting on the towers significantly exceeded that of the forces acting on the piers. In the final test case, severe damage, including concrete crushing and rebar exposure, occurred at the bottom of the middle column – the most critical part of the tower – leading to the inclination of the tower. Damage to the cables or deck was not observed. The finite element model captured the elastic transverse seismic behavior of the test model. [ABSTRACT FROM AUTHOR]

Reinforced concrete (RC) rigid-frame bridges with tall hollow piers were widely constructed in Southwestern China, an earthquake-prone area. For such bridges, the seismic damages may be underestimated if multiple bends of tall piers are overlooked using a conventional damage measure such as the drift ratio. Moreover, the seismic damage assessment can be inaccurate if tall piers' shear damages are ignored using the sectional curvature as a damage measure. Along these lines, this paper proposes a novel seismic damage measure, the piecewise drift ratio (PDR), involving both shear effects and multiple-bend deformations; it has been validated by hybrid tests and analyzed employing fragility curves. Damage state limits represented by the PDR are estimated through statistical analysis of the 40 existing tests of hollow piers. To validate the PDR, a finite element model of an RC rigid-frame bridge with two tall piers was established and adequately calibrated based on model-updating hybrid simulations. To comprehensively evaluate the PDR, ground motions were selected and grouped into four categories by identifying their first two-class nature frequency and their amplitude ratio; to determine fragility curves, both the spectral acceleration at the fundamental period with 5% damping, Sa(T1, 5%), and the peak ground acceleration have been adopted as intensity measures. Results show the effectiveness of the proposed PDR, provide a more severe ground motion for assessment, and reveal the high exceedance probability of the complete damage state of tall piers under some potential seismic scenarios. [ABSTRACT FROM AUTHOR]

In order to understand the stability evaluation method of high fill loess foundation, the author proposes a study on the stability evaluation method of high fill loess foundation based on numerical simulation. The author first established a three-dimensional finite element model of a multi-level high fill slope using PLAXIS 3D software based on a loess high fill slope engineering project in a certain section of northwest China. The study investigated the effects of changes in fill materials, fill boundaries, slopes, and unloading platforms on slope stability. Secondly, based on the vertical and horizontal displacement of the top and foot of each level of slope under step-by-step filling, the distribution pattern of the most dangerous points of each level of slope and the overall deformation trend of the slope were analyzed. The results indicate that the cohesion and internal friction angle of the filling material are key factors affecting the stability of high fill slopes. Reducing the height of the steps at the boundary between the filling and the undisturbed soil, deepening the width of the steps, reducing the slope, and widening the unloading platform can all improve the stability of the slope. During the construction of lower slopes, there is a significant vertical displacement mutation, while the horizontal displacement mutation is relatively slow; After the construction is completed, the deformation situation is good, and the vertical and horizontal displacement of the higher slope during construction changes greatly, with uneven distribution; After the completion of construction, the consolidation settlement period is long and the deformation is large; Emphasis should be placed on strengthening deformation monitoring at high altitudes after construction is completed. Finally, the platform width can be selected within this range based on the actual engineering situation. After the platform width is greater than 3.6m, as sufficient platform width has been reached at this point, further increasing the platform width has little impact on the safety factor, and the curve gradually flattens out. The research results have determined the stability influencing factors, deformation trends, and development laws of loess high fill slopes in the northwest region, providing a scientific basis for further research on deformation control of loess high fill slopes. [ABSTRACT FROM AUTHOR]

Architectural heritage health assessment is the basis of scientific repair and maintenance. However, existing methods do not adequately take into account the fuzziness, randomness and uncertainties unique to architectural heritage assessment. In this paper, a new evaluation model of VM-NCM is constructed by combining variable weight theory and normal cloud model theory. The model enables the combination of qualitative ratings and quantitative calculation, deals with the fuzziness in the assessment process, and resolves the randomness and reflects the uncertainty to a certain extent. Based on constructing the index system combining qualitative and quantitative indexes, the structural index values are acquired by the synergistic coupling of the fine laser point cloud model and finite element structural analysis model. The acquisition of surface index values is completed by the hyperspectral intelligent detection technology of surface materials and diseases. These reduce the generation of ambiguous information in the index detection process. An evaluation study is conducted using the Yingxian wooden pagoda in China as an example. The results show that this method takes into account the fuzziness and randomness in the evaluation process, and obtains more scientific and reliable evaluation results, which provides a research paradigm for assessing the architectural heritage health status. [ABSTRACT FROM AUTHOR]

As urban population increases, integrated underground–aboveground complexes are being constructed at growing paces in major cities. The seismic analysis of such complexes is crucial for the safety and functionality in the threat of potential earthquake disasters. However, fine‐grained numerical modeling and analysis of such large and complex structures are still inefficient due to the consideration of the soil–structure interaction (SSI). To address this challenge, an efficient approach for numerical modeling of large‐scale seismic SSI analysis is presented in this paper to overcome the limitations of existing finite element analysis (FEA) software. Moreover, a multi‐graphic processing unit (GPU) parallel explicit algorithm is implemented for the nonlinear dynamic SSI problems to further increase the computational efficiency. A large underground–aboveground complex project in China is used as an example to demonstrate the capability of the integrated method. The accuracy and reliability of the multi‐GPU parallel explicit finite element algorithm for SSI analysis (GFEA‐SSIA) are verified through a comparative analysis of the linear‐elastic and nonlinear dynamic response of the building calculated by GFEA‐SSIA and common FEA software. Finally, the structural response and structural damage of the underground–aboveground complex are analyzed under multidirectional seismic motions, and the damage distributions of the structures are provided. [ABSTRACT FROM AUTHOR]

Track irregularity is an important factor affecting the train-track-bridge system interaction, and for the seismic design of the track-bridge system, the study of the law of the influence of track irregularity on the train dynamic effect is of great theoretical significance. Based on this, the finite element models of China railway track structure (CRTS) II plate high-speed railway simple-supported girder bridge and CRH2C high-speed train model are developed and compared with the shaking table test results to verify their validity. Considering track irregularity and earthquake randomness, a sample library of the train dynamic effect of the track-bridge system under earthquake is established, the probabilistic statistical characteristics of the train dynamic effect are analyzed, and the influence level of track irregularity on the train dynamic effect of the track-bridge system under earthquake is studied, and the standard value of track irregularity influence coefficient of train dynamic effect based on probability guarantee rate is proposed. The results indicate that: the influence of track irregularity on the seismic response of bridge structure is slight, with their greatest impact not exceeding 1%. However, it has a significant impact on the seismic response of track structures. The standard values of the sliding and mortar layers' track irregularity influence coefficients are 1.49 and 1.71, respectively, at 0.1 g. Under various peak ground acceleration (PGA) settings, the fasteners' standard values for the track irregularity influence coefficient are less than 1.1. Additionally, the degree of influence of track irregularity on the seismic response of track structure decreases significantly as the PGA increases. [ABSTRACT FROM AUTHOR]

Landslides represent one of the most frequent and destructive natural hazards in recent years. In highly seismic countries, the occurrence of large earthquakes is a significant triggering factor in the generation of these landslides. Therefore, it is of interest to various disciplines within civil engineering to study these phenomena through empirical analysis, analytical methods, and numerical modelling, aiming to provide a more accurate representation of these complex phenomena. For this purpose, a computational modelling approach is developed to describe the dynamics of a landslide or rockslide induced by seismic loading, using the Material Point Method (MPM). Presently, the utilization of MPM holds considerable significance because it is a numerical method engineered to simulate large deformations. This stands in contrast to conventional methods like the Finite Element Method (FEM), which struggles to precisely deal with this type of problems due to the generation of errors related to mesh distortion. In this study, it is performed a modelling process involving a real and documented scenario--a massive landslide occurrence in the vicinity of Daguangbao, China, triggered by the 2008 Wenchuan Earthquake. The obtained results successfully capture the landslide dynamics in terms of velocities, deformations, and travel distances in accordance with existing reports and other research endeavours. The maximum attained velocities of the landslide are approximately 100 km/h, affirming the catastrophic nature of this event. [ABSTRACT FROM AUTHOR]

Belled piles are increasingly being employed for transmission tower foundations in the mountainous regions of Western China, but their uplift behavior is not fully understood. This paper presents experimental investigations of the pull-out behavior of belled piles in horizontal and inclined ground (overlying soil and underlying soft rock). 3D non-linear finite element analyses related to the model tests were also conducted using ABAQUS software, and the influence of slope effect on the ultimate uplift capacity of rock-socketed belled piles was evaluated. The results demonstrated that the inclined ground led to deterioration in its uplift performance, thus increasing both the displacement of the pile cap and ground surface. When the slope angle changes between 0° and 30°, the weakening effect of the slope on the ultimate uplift capacity increases linearly. When the slope angle is increased to 45°, the weakening effect of the slope on the ultimate uplift capacity is greatly enhanced, and the relationship between the ultimate uplift capacity of belled piles in the inclined ground and the slope angle is proposed. Moreover, the failure mode of the horizontal bedrock is an inverted cone with a failure angle between 0.8 and 1.0φr (φr is the internal friction angle of bedrock). In contrast, the bedrock failure of inclined ground is bulb-shaped, and it mainly occurs within 4d (d represents pile diameter) of the downslope side. It was also discovered that the downslope side of the belled pile in the sloped ground generated cracks that directed to the pile axis if the pile top load reached 82.3% of the ultimate uplift capacity. These findings are valuable for practicing engineers in the rational design of belled piles, taking account of the weakening effect of inclined ground. Highlights: Reveal the adverse effect of inclined ground on the uplift bearing deformation characteristics of the belled pile. It is clarified that the failure mode of rock-socketed belled piles in inclined ground varies with the slope angle through model test and 3D numerical method. Propose an empirical relationship to quantify the ultimate uplift capacity of rock-socketed belled piles in inclined ground and the slope angle. [ABSTRACT FROM AUTHOR]

Based on the perspective of flight technology and flight safety, the unsaturated clayey foundation soil of a high plateau airport in the mountainous area of southwest China is taken as the research object, and the calculation method of the composite modulus of CFG pile composite foundation with the soil between the piles as the unsaturated soil is established according to the relevant characteristics of unsaturated soil, and the calculation method of the composite foundation's settlement is carried out on the basis of this method. At the same time, Plaxis finite element analysis software is used to model the actual project and numerically analyze the settlement characteristics of the composite foundation. Finally, the calculation results of the two methods are compared and studied with the actual settlement monitoring values on site. The study shows that: 1) the theoretical analysis method is able to consider the effects of pile length, pile modulus, and matrix suction in unsaturated soil of rigid piles on the composite modulus, which is more in line with the reality than the conventional composite modulus method that does not consider the unsaturated nature of the soil between the piles; 2) the resultant values computed by the theoretical and numerical analysis methods recommended in this paper are both smaller than those measured at the site but the difference is within the range of 10%, so that in the actual plateau of the High Plains airports can choose the two analysis methods recommended in this paper to conduct related research. [ABSTRACT FROM AUTHOR]

To improve the out-of-plane collaborative performance of timber frames and walls, a metal connector is proposed and designed. A finite element model of the wall is established, and the composite block damage criteria and surface contact behavior are validated. Additionally, one group without metal connectors and three groups with different numbers of metal connectors placed at various positions in traditional residential wall models are established. Using static loading simulation, the influence of different numbers of metal connectors on the out-of-plane damage patterns, deformation characteristics, and shear force distribution is analyzed. The study reveals that top metal connectors significantly reduce the out-of-plane displacement of the top wall by up to 84.6%. Metal connectors have a significant impact on the deformation capacity of brick walls, with a maximum enhancement of 65.3%. The metal connectors in the middle and lower parts transfer the wall loads to the columns, increasing the horizontal shear at the column head by approximately 7%. The connectors in the middle and lower parts effectively improve the collaborative performance of brick walls and wooden frames. [ABSTRACT FROM AUTHOR]

A Mw 6.6 earthquake struck Luding county, in Sichuan province of China on September 5, 2022, causing severe damage of nearby infrastructures. The earthquake indicates an awakening of southeast branch of Xianshuihe fault since the last 1973 Mw 7.6 Luhuo earthquake in Sichuan, thus attracting attention from the public. A physics-based method, combining spectral element method (SEM) and finite element method (FEM), was presented in this paper to investigate the correlation between near-fault motions and response of a road tunnel, which has a closest distance of about 6.0 km to the fault. This method allows to incorporate the rupture details, geological irregularity, 3D velocity structure, as well as the underground tunnel. The ground motions simulated by SEM were validated by comparison to specific station records and empirical ground motion model (GMM), which were subsequently input into the tunnel to obtain its axial deformation and sectional inner forces. Parametric study on tunnel alignment was conducted, and wavelet transformation was used to extract dynamic pulses from the ground motions. The results show that the tunnel response is remarkably affected by dynamic pulse directivity, and the axial forces could be dominated by permanent fault displacement for tunnel of the strike-normal alignment. [ABSTRACT FROM AUTHOR]

In order to accurately use numerical analysis results to evaluate seismic performance, a quantitative relationship between the parameters of the ideal finite element model (FEM) and full-scale test model (FTM) of historic timber structures must be established. In this study, a single-story full-scale timber structure with four columns and Dou-gongs that was common during the Song dynasty of China (A.D. 960–1279) was taken as the object, and pseudo-static test (or simulation) analysis was carried out on the FTM and the corresponding FEM. The numerical model was consistent with the test model in terms of the structural deformation pattern and stress characteristics of the key nodes. The key-point loads of the skeleton curves, stiffness ratio, ductility coefficient, and stiffness relationship were quantitatively established for the two models. Accordingly, approximate formulas for the above relationships were proposed. [ABSTRACT FROM AUTHOR]

China produces a large amount of corn straw after the harvest of staple grains every year. Fodder application of corn straw can reduce the waste of straw resources. Such usage also can guarantee the supply of highquality coarse fodder for livestock and help the development of husbandry and the increase of production and income of farmers and herdsmen in China. Based on the requirements of livestock for straw feed consumption, the corn straw treatment process engineering was studied, and the overall structure, transmission scheme, and main working components of the corn straw crushing and rubbing filament machine were designed. The equipment was developed with three-dimensional modeling and solid design. Key components were verified through finite element analysis. Finally, a prototype was produced for testing. The experimental results showed that when the moisture content of corn straw was tested to be 20%, the percentage of filamentous straw of the equipment was 97.2%, and the calibrated unit power productivity could reach 82.8 kg/(kW ⋅ h). Through experiments, all indicators of the equipment met the relevant technical standards of the straw crushing and rubbing filament machine, providing theoretical basis and technical support for the design of the straw crushing and rubbing filament machine. [ABSTRACT FROM AUTHOR]

The paper presents the results of computational analysis of the stress-strain state of reinforced concrete spans of the railway (single-track railway line) overpass over the highway, under specified loads using spatial finite element models. The static load consists of a cohesion of three TEM-18 diesel locomotives and two loaded gondola cars (up to 25 tons per axle). The purpose of this study was to ensure reliable and safe operation of artificial structures on the railroads, as there is a constant increase in transit freight trains from China through the territory of Kazakhstan to near and far abroad, and often the load on the axle reaches 25 tons, and sometimes larger values – up to 27 tons per axle. The results of the study are recommended to be used for inspections and tests of typical girder bridge spans, as well as in the case of monitoring their technical condition with increasing operational loads. [ABSTRACT FROM AUTHOR]

Currently, in some domestic and foreign mines, the backfill drilling pipeline experiences a rupture phenomenon even when the wear degree is low. This results in a delay in production due to the filling becoming 'sick'. This paper presents, for the first time, the damage mechanism from a mechanical perspective and re-derives the anti-extrusion strength model of the backfill drilling pipeline. We investigate the influence of the law on the anti-extrusion strength of pipelines from the perspective of strata and cement rings. We then verify the theoretical and simulation results through engineering examples. The results demonstrate that the Mises stress criterion is a suitable modification principle for the anti-extrusion strength model of the backfill drilling pipeline. The anti-extrusion strength of the pipeline is related to the elastic modulus and Poisson's ratio of the stratum, and the thickness of the cement ring. It is negatively affected by the depth of the stratum. For hard strata, a cement ring with a smaller elastic modulus is suitable, while for soft stratum, a cement ring with a larger elastic modulus is recommended. When the missing angle of the cement ring is less than 60°, the stress concentration factor increases up to 2.2. The stress unloading capacity of the cement ring ranges from 32.7% to 37.8%, and optimal performance of the cement ring is achieved when it has high strength and low rigidity. The backfill filling pipeline of a copper mine abroad was destroyed due to external extrusion force exceeding its anti-extrusion strength value. The modified pipeline anti-extrusion strength model is 18.2% higher than the pipeline API strength value. This finding can inform the design of the backfill filling pipeline for China's kilometer-deep wells in the future. [ABSTRACT FROM AUTHOR]

This study aims to determine the cause of a landslide located at Taihu Resort in Suzhou, Jiangsu Province, China. Field monitoring has been conducted, including two-dimensional finite element method (FEM) numerical analyses to examine slope stability under different working conditions. The monitoring data indicated that the slope deformation was triggered in two phases: at a certain period when the slope was cut and moderate rainfall occurred in November; and afterward, when a continuous heavy rainfall intensity hit during the monsoon rainfall, which accelerated sliding of the slope. Numerical simulations show that stress and maximum displacement distributions formed and redistributed during the excavation process, where the shear strain occurred mainly in the front layer of soil. Additionally, the factor of safety of the slope decreases gradually with the increase in the excavation rate. During 15 days of continuous rainfall infiltration, the slope under heavy rainfall indicates a minimum factor of safety (FoS). Specifically, the slope excavation followed by heavy rainfall intensities contributed significantly to the landslide. [ABSTRACT FROM AUTHOR]

We examined the remains of an individual who was unearthed from the Tuchengzi site and was believed to be from the Warring States period in China. The remains exhibited segmental femoral fracture. We aimed to deduce the cause of fracture, medical interventions, healing process, and motion behavior after fracture healing using several techniques, including macroscopic observation, computed tomography (CT), and finite element analysis. Based on the morphology of the long bones, it appeared that the individual was male. The fractures resulted in an adduction angle of 5.47° and an anterior flexion angle of 21.34° in the proximal femur, while the femoral neck anteversion angle had been replaced by a retroversion angle of 10.74°. Additionally, the distal femur formed an abnormal anterior convex angle of 144.60°. CT revealed mature callus formation and visible trabecular bundles. The finite element analysis indicated that the maximum von Mises stress in the femur was 17.44 MPa during standing and 96.46 MPa during walking. We suggest that medical practitioners in the Warring States period possessed a good knowledge of thigh anatomy, enabling them to perform fracture reduction and fixation. Reasonable medical intervention facilitated fracture healing and load recovery. Satisfactory fracture healing ensured that the individual could engage in normal standing and walking activities after rehabilitation. [ABSTRACT FROM AUTHOR]

Aiming at the current low degree of mechanization of pomegranate sprouting tiller pruning in China, all relying on manual pruning, this paper designs a PLC-based pomegranate sprouting tiller removal machine. This machine adopts the identification method of wireless map transmission, the sprouting tiller removal method of multi-cylinder cooperative operation, and the MCGS configuration to realize the interaction between the user and the system, which realizes the displacement and angle compensation of the end-effector under complex conditions to realize the all-around accurate removal of the pomegranate sprouting tiller. The performance test and finite element analysis showed that the device could remove up to 74.62% of sprouting tillers, and the damage rate was as low as 18%. This meets the requirements of pomegranate plantations for the removal of emergent tillers. [ABSTRACT FROM AUTHOR]

High-order polygonal wear of wheels is one of the most severe technical challenges for China's high-speed trains at present, and its formation mechanism has not been thoroughly understood. The effect of train traction on the wheel polygonal wear of high-speed trains was studied based on a wheel/rail rolling contact finite element model. The frequency domain characteristics of unstable vibration of the wheel/rail system under rolling/sliding contact were studied by using the finite element complex modal analysis method. We also examined wheel/rail contact forces and friction in the time domain. The cause of the high-order polygonal wear of Chinese high-speed train wheels was revealed. The effect of the vehicle speed and the wheel diameter on wheel polygonal wear were investigated. The results show: the friction-induced vibration of the wheel/rail system will be excited when the rolling/sliding contact between the wheel and rail. The radial zoom modal of the wheel is an unstable mode, which is the main cause of the 21-22 order polygonal wear of the high-speed train wheels in China. Additionally, vehicle speed has a linear relationship with the order of polygonal wear. Reducing the vehicle speed helps to control the polygonal wear of the wheels. Wheels of different diameters exhibit varying degrees of polygonal wear, with smaller wheels being more resistant to friction-induced vibrations. [ABSTRACT FROM AUTHOR]

Weeds compete with rice for sunlight and nutrients and are prone to harboring pathogens, leading to reduced rice yields. Addressing the issues of low weeding efficiency and weed mortality rates in existing inter-row weeding devices, the study proposes the design of a combination paddy field inter-row weeding wheel. The device's operation process is theoretically analyzed based on the weed control requirements in the northeastern region of China, leading to the determination of specific structural parameters. This research conducted experiments on the mechanical properties of weed cutting to obtain geometric parameters for paddy field weeds. It was found that the range for the cutting gap of the dynamic–fixed blade is between 0.6 mm to 1.4 mm and the cutting angle is between 5° to 15°, resulting in the lowest peak cutting force for weeds. Using LS-DYNA R12.0.0 dynamic simulation software, a fluid–structure interaction (FSI) model of the weeding wheel–water–soil system was established. By employing the central composite experimental design principle and considering the soil stir rate and coupling stress as indicators, the optimal structural parameter combination for the device is obtained: a dynamic–fixed blade cutting gap of 1.4 mm, a cutting angle of 10.95°, and a dynamic blade install angle of −3.44°. Field experiments demonstrated that the device achieved an average weeding rate of 89.7% and an average seedling damage rate of 1.9%, indicating excellent performance. This study contributes to improving weed mortality rates and provides valuable guidance for inter-row mechanical weeding technology. [ABSTRACT FROM AUTHOR]

In recent years, medium- and low-speed maglev trains have been put into use in China. It was discovered during testing that the electric shoegear and conductor rail system generate significant vibration and noise when the electric shoegear passes through expansion and intermediate joints. By analyzing the sound pressure level (SPL) of the noise signal, it was found that the A-weighted SPL of the noise was between 77.83 dBA and 91.80 dBA, when the maglev trains were running normally, which reached the level of annoyance. Based on the theory of self-excited frictional vibrations, the finite element models of an electric shoegear and conductor rail system (shoe–rail system) were established. The main frequency of the vibration signal calculated by the transient dynamic analysis method was 1510.05 Hz. The self-excited frictional vibrations of the system were further studied using the complex eigenvalue analysis (CEA), and the causes of the noise are analyzed. The results show that the system has unstable vibration when the friction coefficient was greater than or equal to 0.21. The parameter sensitivity analysis showed that the slip shoe material of the electric shoegear, vertical damping of the suspension device, and tuned mass damper (TMD) structure have an important influence on the generation of vibration and noise of the system. Installing an appropriately tuned mass damper structure can suppress or eliminate the unstable vibration of the system. [ABSTRACT FROM AUTHOR]

BACKGROUND: At present, wrist protection products designed in and outside China have not solved the contradiction between protecting the wrist joint from injury and maintaining the flexible movement of the wrist joint. OBJECTIVE: To investigate the biomechanical mechanism of dorsiflexion injury of the wrist joint in elderly people after falls, and to provide a biomechanical basis for the prevention and treatment of wrist injury in elderly people after falls. METHODS: A 65-year-old man was selected to obtain the original data by uninterrupted CT scan of the middle and lower 2/3 of his left forearm up to the end of the finger. A finite element model of wrist dorsiflexion was established using ANSYS 12.0 finite element software. The palm surface of the model was constrained, and the model at a velocity load of 2 m/s in the direction of vertical downward was given to simulate the injury state of the palm when the elderly fall. The stress distribution of the soft tissues and bones of the wrist joint and the change of the stress with time were observed after the load was applied. RESULTS AND CONCLUSION: (1) A realistic and effective finite element model of the dorsal extension position of the wrist joint of the elderly was established. The soft tissue stresses were mainly concentrated in the small fissure of the palm and the dorsal side of the wrist after loading. The skeletal stresses were mainly concentrated in the lower end of the ulnar radius dorsally. The stresses in the lower end of the radius were the greatest. The palmar stresses were mainly concentrated in the middle and lower 1/3 of the radius and the hook bone. The stress distribution of the ulnar radius was asymmetric, and the stresses in the radius were more concentrated. (2) The results of the study are consistent with the clinical situation of a fallen wrist injury in elderly people, and can be used to explain the mechanism of wrist dorsiflexion injury, which can provide the biomechanical basis for the design of wrist protection devices that can be used to prevent wrist injury induced by falling and the treatment of wrist injury in elderly people. [ABSTRACT FROM AUTHOR]

Based on the average human body size in China and the THUMS AM50 finite element model of the human body, the Kriging interpolation algorithm was used to model the Chinese 50th percentile human body, and the biological fidelity of the model was verified. We built three different types of passenger vehicle models, namely, sedan, sports utility vehicle (SUV), and multi-purpose vehicle (MPV), and used mechanical response analysis and finite element simulation to compare and analyze the dynamic differences and head injury differences between the Chinese 50th percentile human body and the THUMS AM50 model during passenger vehicle collisions. The results showed that there are obvious differences between the Chinese mannequin and THUMS in terms of collision time, collision position, invasion speed, and angle. When a sedan collided with the mannequins, the skull damage to the Chinese human body model was more severe, and when a sedan or SUV collided, the brain damage to the Chinese human body was more severe. The abovementioned results suggest that the existing C-NCAP pedestrian protection testing regulations may not provide the best protection for Chinese human bodies, and that the regulations need to be improved by combining collision damage mechanisms and the physical characteristics of Chinese pedestrians. This thorough investigation is positioned to shed light on the fundamental biomechanics and injury mechanisms at play. Furthermore, the amalgamation of clinically rooted translational and engineering research in the realm of traumatic brain injury has the potential to establish a solid foundation for discerning preventive methodologies. Ultimately, this endeavor holds the potential to introduce effective strategies aimed at preventing and safeguarding against traumatic brain injuries. [ABSTRACT FROM AUTHOR]

During pipeline construction and operation, the occurrence of surface dents presents a critical concern, primarily arising from factors such as pipeline installation and geological forces exerted upon the pipeline, particularly in the form of rock protrusion. These dents pose a significant threat to the pipeline's safe functionality and have the potential to diminish its load-bearing capacity. Presently, China's oil and gas pipelines predominantly employ X80 high-grade steel. It is noteworthy that prior research into the ultimate load capacity of dented pipelines has largely centered on medium and low-grade steels. The implications of these findings for the suitability of the X80 pipeline remain inconclusive. Consequently, it is imperative to undertake a comprehensive investigation into the load-bearing capacity of high-grade steel pipelines with dent defects. In addition to internal pressure, variations in the pipeline's transported medium, ambient temperature fluctuations, soil displacement, and other factors introduce additional loading effects, including bending moments and axial loads. These supplementary loads introduce latent hazards to the pipeline's operational safety. Hence, this research endeavors to investigate the ultimate load-bearing capacity of X80-grade dented pipelines under the influence of typical loading conditions and to identify pertinent factors that affect this capacity. Finite element analysis (FEA) is deployed to study the behavior of the dented pipelines under typical loads. Failure criterion for ascertaining the ultimate load is proposed and verified by the comparison to test results. Furthermore, the impact of varying dent sizes on the ultimate load capacity of X80-grade dented pipelines is examined. These findings serve as a robust foundation for the safety assessment of dented pipelines, ensuring the sustained safe operation of these vital infrastructures. [ABSTRACT FROM AUTHOR]

A rock-filled concrete (RFC) dam is an original dam construction technology invented in China nearly 20 years ago. The technology has been continuously improved and innovated upon, and the accumulated rich practical experience gradually formed a complete dam design and construction technology. Seismic design is a key design area for RFC dams that still requires more investigation; therefore, this article attempts to address some questions in this area. In the article, the seismic design for a curved gravity dam, currently under construction, is compared for RFC and conventional vibrating concrete (CVC) dam alternatives based on American design documents. The conclusions drawn from investigations include the following: The displacement and stress distributions in both the CVC and RFC alternatives are similar, but the maximum computed values for the RFC dam model are slightly smaller than those for the CVC one, while the sliding resistance of both dam alternatives can meet the requirements of the specifications. Regarding the nonlinear seismic analysis results, the extent of damage in the RFC dam model is significantly reduced when compared with the CVC model, which can be explained by the higher cracking resistance of RFC. In general, the seismic performance of the investigated dam made of RFC appears to be better than that of CVC. [ABSTRACT FROM AUTHOR]

Geological hazards, especially landslides and mudslides, are frequent in Caoke County, Sichuan Province, China. In September 2022, the mechanical parameters of the soil were obtained through a basic investigation of the landslide characteristics of Ni changgou. Upon that, the finite element-discrete element method was used to reconstruct the three-dimensional numerical model of the landslide on the right bank of Ni changgou, and the initiation mechanism of rainfall on landslide and the formation of debris flow impact dam process were simulated. Furthermore, the pore pressure, stability coefficient as well as displacement of the landslide body were analyzed. It turned out that with the increase of rainfall intensity, the pore water pressure value also increases, where pore water pressure rises rapidly. the slope is close to the unstable edge, Eventually, it tends to one under rainfall conditions, and due to gravity, the slide of the landslide is induced. The duration of landslide movement is about 200 s, the maximum average velocity of the landslide reaches 4.85 m/s, and the average movement distance is close to 500 m. In addition, this method is applied to the Chutougou debris flow, and the corresponding hazard analysis is added which could better show the treatment and application of debris flow in actual engineering. [ABSTRACT FROM AUTHOR]

Sag is one of the important indicators for judging whether a transmission line is safe. The existing sag calculation method does not consider the temperature difference between conductor strands, causing the calculated results to often deviate from the values measured with a theodolite. In this article, a sag calculation method considering the temperature difference between strands is proposed. First, finite element analysis and experiments were used to analyze the temperature differences between each area and layer of the conductor when the wind blew the conductor, and then a correction calculation model for the conductor sag was proposed. Next, a sag monitoring system based on four-point temperature measurement was designed. Finally, the method was applied to a ±400 kV transmission line in Qinghai Province, China. The results show that after considering the temperature difference in the conductor strands, the error of the sag calculation result is much smaller than that without considering the temperature difference in the conductor strands, and the maximum relative error is reduced from 7.86% to less than 2%. [ABSTRACT FROM AUTHOR]

Due to the large daily temperature difference on the ultra-high altitude plateau of China, the actual vertical temperature gradient (TG) of ballastless track may exceed the design value in the Code. The temperature monitoring platform of the double-block ballastless track was established to obtain the temperature distribution characteristics of track. The finite element model of the temperature field of the track is developed to study the warping deformation of track, and then the influence of TG on the dynamic responses of the vehicle-track-bridge system (VTBS) are investigated. The results show that the maximum positive temperature gradient (PTG) and negative temperature gradient (NTG) of the track bed slab are 88.875 ℃/m and − 47.159 ℃/m, respectively, and the latter exceeds the design value in the Code. The dynamic responses are positively correlated with the TG, and the influence of the NTG is more significant. The dynamic response of the rail is most sensitive to the TG. [ABSTRACT FROM AUTHOR]

Background: Adolescent idiopathic scoliosis (AIS) is often accompanied by osteopenia and osteoporosis, which can cause serious complications. The aim of this study was to determine the specific bone mineral density (BMD) of each vertebral body in patients with AIS using biomechanical finite element modeling based on three-dimensional (3D) reconstruction. Methods: This retrospective study involved 56 patients with AIS. Computed tomography (CT) and radiography were performed. Spinal vertebrae were segmented from the spinal CT images of patients with AIS to reconstruct 3D vertebral models. The vertebral models were meshed into tetrahedral finite elements to assess the BMD. Results: The mean main curve Cobb angle was 88.6 ± 36.7°, and the mean kyphosis angle was 36.8 ± 31.5°. The mean BMD of the global spine was 0.83 ± 0.15 g/cm2. The highest BMD was measured on the concave side of the apex (0.98 ± 0.16 g/cm2). Apical vertebral BMD was negatively correlated with age and height (r = − 0.490, p = 0.009 and r = − 0.478, p = 0.043, respectively). There were no significant differences in BMD values between the concave and convex sides (p > 0.05). Conclusions: The 3D finite element modeling of BMD in patients with AIS is a reliable and accurate BMD measurement method. Using this method, the overall BMD of patients with AIS was shown to gradually decrease from the top to the bottom of the spine. Our findings provide valuable insights for surgical planning, choice of screw trajectories, and additional biomechanical analyzes using finite element models in the context of scoliosis. [ABSTRACT FROM AUTHOR]

According to the characteristics of complex terrain and bad geological conditions in the southwest mountainous area of China, it is proposed that cast-in situ double-block ballastless track with layers and blocks structure should be adopted preferentially in the subgrade section of high-speed railway, which is conducive to the construction, prolongation of service life and maintenance of the ballastless track. Based on the finite element model, the dynamic performance, structural strength and stability of double-block ballastless track under high earthquake-intensity action are analyzed. The analysis shows that the relative displacement between the base slab of ballastless track and the subgrade may occur under 9 degree earthquake action. A new CRTS double-block ballastless track structure with a concave-convex structure between the base slab and the subgrade is proposed in the subgrade section, and its additional stress and relative displacement under earthquake are analyzed. The results show that the additional stress and relative displacement of the new ballastless track structure and the subgrade under 9- degree earthquake actions are small, which meet the high stability requirements of high-speed railway. [ABSTRACT FROM AUTHOR]

With the rapid increase in offshore wind turbines in China, monopiles with diameters exceeding 2 m are widely used. As these piles are subjected to lateral loads caused by wind, waves, and currents, the designs of the pile foundations supporting the offshore wind turbines are significantly influenced by their lateral behaviors. For this reason, field tests of the largest monopile on the sea and additional analysis based on the solid finite element method (FEM) and p-y curves are carried out to reveal the response of monopiles subjected to lateral loads and to figure out key technical issues related to the design process. The results revealed that the p-y curves proposed by the API code for clay showed a much "softer" response, which resulted in the conservative design of the piles. The solid FEM relied heavily on the choosing of the parameters used. At relatively small deflections, the solid FEM presented reasonable results as compared with the tests which were, however, supposed to overestimate the ultimate capacity of the piles. The results also indicated the importance of the influence of the pile–soil gap and the application of parameter analysis to achieve relatively conservative results, if the solid FEM is adopted in the design. [ABSTRACT FROM AUTHOR]

In recent years, with the completion of the construction of large-scale hydropower projects in China, a series of engineering geological problems that occurred during the operation of the hydropower station have become an important issue affecting the normal operation of hydropower stations. Landslides on reservoir slopes triggered especially by water storage and other factors related to the construction of hydropower stations seriously affect the normal operation of the hydropower station and lead to other geological disasters. Research indicates that many reservoir-area landslides are triggered by hydrodynamic forces resulting from water level fluctuations in hydroelectric power stations. The Mala landslide of Miaowei Hydropower Station in the Lancang River Basin of China is taken as the engineering example to study the influence of hydrodynamic forces on the deformation characteristics and stability trends of the landslide. This paper explores the formation mechanism and influencing factors of the Mala landslide by conducting a field investigation of the Mala landslide and analyzing the monitoring data. Additionally, this paper also discusses the impacts of water storage, rainfall, and engineering construction on landslide induction. It is considered that the evolution of the Mala landslide from the initial stage of water storage to the current state mainly includes four stages: small-scale bank collapse stage, creep deformation stage, accelerated sliding stage, and uniform sliding stage. Moreover, the changes in the trend of landslide stability are analyzed using the two-dimensional finite element method. The research results provide a valuable reference for understanding the formation mechanism and predicting the deformation of reservoir landslides, which has considerable engineering practical significance. [ABSTRACT FROM AUTHOR]

Sanding production of the underground gas storage (UGS) in the depleted reservoir will cause the decline of effective storage capacity, and the erosion of well string and auxiliary equipment, and other engineering problems. A deep understanding of the sanding production contributes to maintaining the injection and production capacity of gas storage and the long‐term safety of the UGS. In this paper, core samples of five main sedimentary microfacies were drilled from the UGS in middle China. The mechanical properties with different conditions of the moisture content in multi‐cycling injection–production process were tested. The critical drawdown pressure (CDP) calculation methods for the UGS were established based on the stress analysis near the wellbore and the Mogi–Coulomb criterion. Adopting the finite element method simulation on the geological model of the target UGS, the geo‐stress of the formation was calculated by inversed analysis and validated based on the Kaiser effect of rock. Then, the CDP of two target wells of the UGS were investigated. The effects of the water moisture and the cycling times of the injection–production process on the CDP were also analyzed. The geo‐stress distribution shows that the horizontal maximum principal stress ranges from 53 to 68 MPa, and the horizontal minimum principal stress is 46–58 MPa in the target reservoir section, and the vertical minimum principal stress is 69–77 MPa in the target reservoir. The calculated CDP changed with the types of the sedimentary microfacies in the range of [6.27, 8.77] MPa, in which the CDP of the mixed mud and sand flat sedimentary facies was the lowest. The weakness of the CDP with the increasing of the moisture content and the cycling times were analyzed quantitively. [ABSTRACT FROM AUTHOR]

As an important oil crop in China and the world, the harvesting problem of Camellia oleifera has attracted much attention. Research is needed on mechanical characteristics of harvesting equipment. Explicit dynamics was used to establish a finite element model under a simulated load response to the branch-pedicel-fruit system of C. oleifera to predict the fracture process at the pedicel junction. The separation mechanism of C. oleifera fruit was determined by measuring the constitutive parameters of fruit branches and pedicels and conducting separation experiments and explicit dynamics simulations on different hanging fruits. The maximum stress at the fruit pedicel was 1.14 MPa, and the goodness of fit between the simulation and experiment was approximately 89.5%, indicating that the branch-pedicel-fruit finite element model could accurately reflect the fruit shedding process and that the pedicel diameter was correlated positively with the separation force. This study provides technical parameters for the optimized design of existing C. oleifera harvesting equipment. [ABSTRACT FROM AUTHOR]

This paper examines the dynamic performance of the pantograph passing through an overlap section of the catenary system, using a China's high speed railway with the 4-span overlap as an example. The pantograph and catenary system are simulated as a lumped mass model and finite element model, respectively. The model is verified according to EN50318:2018. The model is also assessed against an experimental study of the contact force and uplift of contact wire at 300 km/h. Then the contact force and uplift of contact wire at the speed of 150–350 km/h are calculated. The research shows that when the pantograph passes through the overlap, the maximum contact force increases beyond 14%, the standard deviation of the contact force increases by more than 26%, and the increase of the vertical displacement exceeds 38%, which becomes more apparent with the increase of speed. Under the influence of aerodynamic force, when the running speed increases from 150 to 350 km/h, the mean contact force in the knuckle-downstream and knuckle-upstream orientation increase by 59.49% and 97.85%, respectively. As a result, the contact force and vertical displacement increase greatly when passing through the overlap section, which could affect the current collection quality. [ABSTRACT FROM AUTHOR]

Gobi solar greenhouses (GSGs) with trapezoidal cross-section walls, through the passive utilisation of solar energy, provide appropriate environmental conditions for sustainable crop growth in otherwise non-arable lands. The Hexi Corridor in China is known for its serious desertification and cold climate putting pressure on the regional GSG production; there, auxiliary heating strategies according to the greenhouse thermal load are required for maintaining plant thermal comfort. However, the highly transient heat transfer of the trapezoidal cross-section wall makes the GSG thermal-load evaluation challenging. This study proposes a new, simple, and accurate approach for calculating the dynamic heat transfer of the trapezoidal cross-section wall. The heat-transfer resistances quantifying the steady-state thermal behaviour of the wall and the unit frequency-response functions describing the transient one were obtained by using discrete Fourier series and a two-dimensional frequency-domain finite-element model. These predetermined factors allowed the calculation of the hourly space-heat gain through the trapezoidal cross-section wall in a spreadsheet under arbitrary boundary conditions. The new approach was experimentally validated under different weather conditions. Furthermore, a GSG thermal-load prediction model was developed. The results showed that, in a typical sunny phase, the heating load occurred around 8:00 and lasted four hours every day, averaging 0.56 GJ per day; in the coldest phase, the heating load occurred during the entire daytime and part of the night-time, averaging 1.42 GJ per day. This approach should be insightful regarding the heating-system planning during GSG design and environment-regulating judgement during GSG operation. • A frequency domain finite element model for trapezoidal cross-section wall. • Steady-state and transient thermal behaviours of trapezoidal cross-section wall. • A simple and accurate heat transfer calculation for trapezoidal cross-section wall. • A simplified calculation of Gobi solar greenhouse thermal load in China. • Dynamic thermal load of Gobi solar greenhouse in cold seasons of the Hexi Corridor. [ABSTRACT FROM AUTHOR]

Traditionally, temperature control for massive concrete structures during the construction phase is based on experience instead of using advanced methods such as predictive control method. In this paper, a predictive control method with a hybrid data-based artificial neural network (ANN) model is proposed. The main parameters of the numerical model are identified based on the data measured from the site. Since the limitation of the measured data, a rich dataset is generated by the numerical model with the identified parameters. Finally, a hybrid data-based ANN model for predicting the temperature indicator of massive concrete is developed. A case study in which the temperature control of concrete in a real bridge anchorage foundation construction in Southwestern China is conducted. Results show that the maximum temperature of concrete can be controlled around the target temperature by the proposed method. The average temperature decline rate decreases from 0.19 °C/h to 0.14 °C/h in the period of 120 h (i.e., from 60 h to 180 h after the concrete pouring) at a sudden decrease of 8 °C in environmental temperature, thereby enabling a significant reduction in the risk of concrete cracking. [ABSTRACT FROM AUTHOR]

Existing seawalls along the eastern coast of China are increasingly becoming the focus of upgrade operations. Concerns arise regarding the settling and stability of seawalls built on soft clayey seabed during upgrade operations. Pore water pressure (PWP) and horizontal displacement accumulations induced by combined tide and wave loadings are observed in in-situ measurements of the clayey seabed underneath the seawall. The measurement results show clear correlations between the oscillations of excess PWP and variations in the tidal height. To reproduce the quasi-static interaction behaviors of the gravity-type seawall and clayey seabed under combined cyclic loadings from waves and currents, a finite element model has been built after incorporating a stiffness degradation law that is evaluated from laboratory triaxial tests on the seabed soil. Demonstrably, with a suitable stiffness degradation law for the seabed soil, the accumulative behaviors can be reasonably reproduced using finite-element modeling. [ABSTRACT FROM AUTHOR]

BACKGROUND: Adolescent idiopathic scoliosis has a high prevalence and complex condition in China and has a significant risk to the physical and mental health of adolescents. The establishment of finite element models based on patient medical images can effectively analyze spinal stresses, simulate the recovery effects of different treatments, and provide a scientific basis for the selection of patient treatment modalities. However, there are many different ways to build finite element models and no unified standard has been formed yet; the quality of models varies and the validation methods need to be improved. OBJECTIVE: The current status of modeling studies in adolescent idiopathic scoliosis in recent years is reviewed in terms of software selection, modeling of key structures (vertebral body, disc, ligament, and trunk models), and material allocation. The research progress of model validation is outlined from the perspectives of geometry, comparison of existing literature, and experimental validation. The deficiencies and development directions of finite element models are summarized to provide references for related studies. METHODS: The first author searched the Web of Science and China National Knowledge Infrastructure databases in December 2021 for relevant literature published from January 2010 to the present, using “adolescent idiopathic scoliosis, finite element, biomechanics” as Chinese and English search terms. The highly cited authoritative articles were traced, and finally 83 articles were included for analysis. RESULTS AND CONCLUSION: (1) Finite element analysis method can reconstruct the three-dimensional model of spine, simulate the physiological state of spine through biomechanical analysis, and provide theoretical basis and scheme reference for conservative treatment and surgical treatment of adolescent idiopathic scoliosis. (2) The establishment method of finite element model in China is different from that outside China. Domestic researchers use full spinal CT to reconstruct the vertebrae through reverse engineering and establish intervertebral discs, ligaments, articular cartilage endplate, up and down structure according to the model of vertebrae. However, the foreign researchers use multiple plane X-ray devices such as the EOS imaging system, which is lack of description of the model establishment process. (3) Although the specific software selection in the process of model building is different, the software classification includes medical image processing software, three-dimensional modeling software and finite element analysis software. (4) The finite element material assignment of vertebrae and intervertebral discs has formed a unified standard, but the material assignment of ligament model is also different due to different unit settings, and the assignment of ligament will significantly affect the results of the model. (5) The verification methods of finite element models mainly include geometric verification compared with original medical images, mechanical verification compared with existing literature results and clinical trial verification of finite element analysis results. [ABSTRACT FROM AUTHOR]

In seismically active regions, high-filled embankment slopes on liquefiable soils tend to damage after strong earthquakes. Therefore, post-seismic damages should be estimated as soon as possible to mitigate potential losses. Fragility function is an efficient tool for assessing the seismic vulnerability conditions of structures, which links the probability of exceeding different limit states to seismic intensity. An embankment slope on liquefiable soils at Yading Airport in China was selected as the study object, and a series of numerical analyses of the embankment-foundation system utilizing the finite element method were conducted. Advanced dynamic constitutive models considering liquefaction and hysteresis characteristics were also adopted to simulate the nonlinear stress–strain behavior of soils under cyclic loadings. The post-seismic stability of embankment slopes was assessed using the strength reduction method (SRM) based on the stress–strain analysis. On this basis, the permanent ground deformation (PGD) at the ground-free field conditions was selected as the intensity measure (IM), while the factor of safety (FoS) of the slopes was selected as the damage measure (DM). Then, a procedure was presented for deriving seismic fragility functions with different damage states in light of incremental dynamic analysis (IDA). This paper aims to investigate the effects of different embankment typologies, such as the thickness of liquefiable soils and slope inclination, on the post-seismic vulnerability of embankment slopes. The fragility curves constructed in this study may soon be helpful for predicting the post-seismic damage of similar high-filled embankment slopes on liquefiable soils, which enables efficient traffic control and rapid disaster response. [ABSTRACT FROM AUTHOR]

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China's grotto temples have suffered from the erosion caused by shallow-surface peeling diseases for many years, and the common protection technology cannot solve such problems. Therefore, in view of the characteristics of wide distribution, small rock separation parts, and shallow layers of spalling diseases in cave temples, the microrockbolt anchoring technology was adopted for treatment. On the basis of the finite element method, the pulling process of microrockbolt-grouting body was simulated, the interface bonding mechanical property between microrockbolt and grouting materials was explored, and the influence of different rockbolt diameters and anchorage lengths on the microrockbolt pulling force was analyzed under monotonic load. Results show that all the failure forms are bolt pulling out failure. With the increase in anchorage length and reinforcement diameter, the axial stress in the anchoring section decreases gradually, and the stress decreases almost uniformly along the anchorage length. The increase in steel bar diameter causes the ultimate pulling force of microbolt to increase. With the increasing of anchorage length, the ultimate pulling force of microbolt increases, but the increase rate decreases. The average interface bond strength decreases when the anchorage length is 100-250 mm. The conclusions obtained in this study provide a significantly reference for the microrockbolt anchoring treatment in cave temples with shallow-surface spalling diseases. [ABSTRACT FROM AUTHOR]