Discontinuities are often considered as important factors responsible for the instability caused by shear failure in engineering rock mass,and energy-driven instability is the root cause of rock failure.However,few st...Discontinuities are often considered as important factors responsible for the instability caused by shear failure in engineering rock mass,and energy-driven instability is the root cause of rock failure.However,few studies focus on the energy evolution during the failure process using a three-dimensional(3D)numerical model.In this study,a series of laboratory direct shear tests on rock-like samples is numer-ically simulated using bonded particle models(BPMs)with multiple combinations of discontinuous in the particle flow code(PFC3D),in which the location and size of the particles conform to the uniform distribution.The effects of joint row number and inclination on the stress-strain characteristics and failure mode of rock were studied from the perspective of microcrack growth and energy evolution.The results showed that,when the number of joint rows Nr>1,the shear failure region does not change with the increase of Nr for the type B(2-columnn multiple-row at center)and the type C(2-column multiple-row at edge)as compared to the type A(1-column multiple-row at center)joint models.Notably,joints significantly increase the post-peak energy dissipation but have little effect on the proportion of energy before the peak.Friction consumes most of the energy while kinetic energy accounts for less than 1%of total energy during the shear process.Peak elastic strain energy follows the variation trend of peak shear displacement.The development and accumulation of microcracks directly affect the energy dissipation,and there is a significant linear relationship between the cumulative number of critical microcracks and the critical dissipated energy at the failure,when the dip direction of joints is opposite to the shear direction,more microcracks will be accumulated at the peak time,resulting in more energy dissipation.The results contribute to deeply understanding the shear failure process of non-persistent jointed mass.展开更多
Several constructions in the field of civil engineering quite often need to deal with rocks.Strength behaviour of rock intersected by a discontinuity or a set of discontinuities has been a topic of keen interest for e...Several constructions in the field of civil engineering quite often need to deal with rocks.Strength behaviour of rock intersected by a discontinuity or a set of discontinuities has been a topic of keen interest for engineering community.The popular attributes of discontinuities that have been given due importance are their frequency,orientation and surface characteristics.Non-persistency,however,has been given little attention.This article presents an experimental study wherein focus has been made on the effect of non-persistency of the joint on the uniaxial compressive strength(UCS)of a model rock for various geometries such as orientation,discontinuity length ratio and number of joint segments.The applicability of single plane of weakness theory(SPWT)to assess the strength of jointed specimens has also been evaluated.It has been noticed that SPWT captures the strength behaviour only for a narrow range of discontinuity orientations.As an improvement,an approach is suggested by extending concepts of degree of persistence and joint factor to have a better understanding towards strength behaviour of rocks intersected by non-persistent joints.展开更多
The stability of underground excavations is influenced by discontinuities interspaced in surrounding rock masses as well as the stress condition. In this work, a numerical study was undertaken on the failure behavior ...The stability of underground excavations is influenced by discontinuities interspaced in surrounding rock masses as well as the stress condition. In this work, a numerical study was undertaken on the failure behavior around a circular opening in a rock mass having non-persistent open joints using PFC software package. A parallel-bond stress corrosion(PSC) approach was incorporated to drive the failure of rock mass around the circular opening, such that the whole progressive failure process after excavation was reproduced. Based on the determined micro parameters for intact material and joint segments, the failure process around the circular opening agrees very well with that obtained through laboratory experiment. A subsequent parametric study was then carried out to look into the influence of lateral pressure coefficient, joint dip angle and joint persistency on the failure pattern and crack evolution of the rock mass around the circular opening. Three failure patterns identified are step path failure, planar failure and rotation failure depending on the lateral pressure coefficient. Moreover, the increment of joint dip angle and joint persistency aggravates the rock mass failure around the opening. This study offers guideline on stability estimation of underground excavations.展开更多
Pre-existing discontinuities change the mechanical properties of rock masses,and further influence failure behavior around an underground opening.In present study,the failure behavior in both Inner and Outer zones aro...Pre-existing discontinuities change the mechanical properties of rock masses,and further influence failure behavior around an underground opening.In present study,the failure behavior in both Inner and Outer zones around a circular opening in a non-persistently jointed rock mass under biaxial compression was investigated through numerical simulations.First,the micro parameters of the PFC^(3D) model were carefully calibrated using the macro mechanical properties determined in physical experiments implemented on jointed rock models.Then,a parametrical study was undertaken of the effect of stress condition,joint dip angle and joint persistency.Under low initial stress,the confining stress improves the mechanical behavior of the surrounding rock masses;while under high initial stress,the surrounding rock mass failed immediately following excavation.At small dip angles the cracks around the circular opening developed generally outwards in a step-path failure pattern;whereas,at high dip angles the surrounding rock mass failed in an instantaneous intact rock failure pattern.Moreover,the stability of the rock mass around the circular opening deteriorated significantly with increasing joint persistency.展开更多
During the excavation of large-scale rock slopes and deep hard rock engineering,the induced rapid unloading serves as the primary cause of rock mass deformation and failure.The essence of this phenomenon lies in the o...During the excavation of large-scale rock slopes and deep hard rock engineering,the induced rapid unloading serves as the primary cause of rock mass deformation and failure.The essence of this phenomenon lies in the opening-shear failure process triggered by the normal stress unloading of fractured rock mass.In this study,we focus on local-scale rock fracture and conduct direct shear tests under different normal stress unloading rates on five types of non-persistent fractured hard rocks.The aim is to analyze the influence of normal stress unloading rates on the failure modes and shear mechanical characteristics of non-persistent fractured rocks.The results indicate that the normal unloading displacement decreases gradually with increasing normal stress unloading rate,while the influence of normal stress unloading rate on shear displacement is not significant.As the normal stress unloading rate increases,the rocks brittle failure process accelerates,and the degree of rocks damage decreases.Analysis of the stress state on rock fracture surfaces reveals that increasing the normal stress unloading rate enhances the compressive stress on rocks,leading to a transition in the failure mode from shear failure to tensile failure.A negative exponential strength formula was proposed,which effectively fits the relationship between failure normal stress and normal stress unloading rate.The findings enrich the theoretical foundation of unloading rock mechanics and provide theoretical support for disasters prevention and control in rock engineering excavations.展开更多
The structural principles of traditional Chinese mortise-and-tenon joints have inspired breakthroughs in supramolecular engineering.Nevertheless,substantial challenges remain in constructing nanoscale supramolecular a...The structural principles of traditional Chinese mortise-and-tenon joints have inspired breakthroughs in supramolecular engineering.Nevertheless,substantial challenges remain in constructing nanoscale supramolecular architectures with precisely controlled giant dimensions.Herein,we report a precision-guided synthetic strategy for constructing giant 2D and 3D supramolecular architectures with rhomboidal motifs,which was achieved through a dovetail joint strategy.Initial assembly of bis-mortise ligand L1 with dovetail tenon ligand L2 in the presence of Cd^(2+)ions yielded the fundamental bis-rhombic supramolecule R1.Subsequent structural elaboration of the dovetail tenon motif enabled the development of multitopic ligands L3 and L4,which facilitated the construction of expanded architectures of the giant bis-propeller supramolecule R2 and tris-propeller supramolecule R3.The synthesized supramolecules R1-R3 were fully characterized multidimensional NMR spectroscopy,electrospray ionization mass spectrometry(ESI-MS),traveling wave ion mobility mass spectrometry(TWIM-MS),transmission electron microscopy(TEM),and atomic force microscopy(AFM).This work develops an innovative dovetail-joint assembly strategy for constructing rigid giant supramolecular architectures,establishing a new paradigm for precision engineering of complex 3D molecular systems.展开更多
With the intensification of population aging,knee and hip joint replacement surgeries have become core methods for treating end-stage joint diseases,with over a million cases performed globally each year.Postoperative...With the intensification of population aging,knee and hip joint replacement surgeries have become core methods for treating end-stage joint diseases,with over a million cases performed globally each year.Postoperative rehabilitation nursing,as a crucial aspect of enhancing surgical outcomes,reducing complications,and facilitating patients’return to normal life,has its scientific and effective protocols directly influencing patient prognosis.This article systematically reviews the core research findings on rehabilitation nursing after joint replacement surgery based on the concept of evidence-based medicine,aiming to provide references for the formulation of standardized and personalized rehabilitation nursing plans in clinical settings.展开更多
[Objectives]To investigate the clinical effects of implementing structured phased rehabilitation training,in addition to conventional rehabilitation,on shoulder joint function and pain alleviation in patients with rot...[Objectives]To investigate the clinical effects of implementing structured phased rehabilitation training,in addition to conventional rehabilitation,on shoulder joint function and pain alleviation in patients with rotator cuff injuries managed conservatively.[Methods]Eighty patients diagnosed with rotator cuff injury were selected and randomly assigned to either the control group or the experimental group,each comprising 40 individuals.The control group received conventional rehabilitation treatment,whereas the experimental group underwent phased rehabilitation training in addition to the conventional treatment for 6 weeks.Assessments were conducted prior to treatment,6 weeks following treatment,and 8 weeks after the completion of treatment(follow-up period).The visual analogue scale(VAS)was employed to evaluate pain intensity,the Constant-Murley score was utilized to assess shoulder joint function,and the shoulder joint range of motion was measured.[Results]Prior to treatment,no statistically significant differences were observed between the two patient groups across all measured indicators(P>0.05).Following 6 weeks of treatment and throughout the follow-up period,both groups exhibited significant reductions in VAS scores compared to baseline measurements,alongside improvements in Constant-Murley scores and shoulder joint range of motion(P<0.05).Furthermore,the magnitude of improvement in the experimental group was significantly greater than that in the control group(P<0.05).[Conclusions]Phased rehabilitation training can enhance shoulder joint function and alleviate pain in patients with rotator cuff injuries beyond the effects of conventional rehabilitation treatment,demonstrating notable clinical application value.展开更多
The widespread use of herbicides such as glyphosate isopropyl amine salt(GIS)and atrazine(ATZ)poses significant risks to aquatic ecosystems.This study investigated the single and joint acute toxicity of a 1:1 GIS-ATZ ...The widespread use of herbicides such as glyphosate isopropyl amine salt(GIS)and atrazine(ATZ)poses significant risks to aquatic ecosystems.This study investigated the single and joint acute toxicity of a 1:1 GIS-ATZ mixture on zebrafish(Danio rerio).Acute tests determined 96-h LC_(50) values of 123.41 mg/L for GIS and 103.95 mg/L for ATZ.In the joint toxicity test,these values decreased to 60.96 and 50.88 mg/L,respectively.The Additive Index(AI)analysis revealed a consistent synergistic interaction between the herbicides at all exposure intervals.These findings underscore the enhanced ecological threat of herbicide mixtures and highlight the necessity of considering joint effects in environmental risk assessments.展开更多
To address the issues of frequent identity switches(IDs)and degraded identification accuracy in multi object tracking(MOT)under complex occlusion scenarios,this study proposes an occlusion-robust tracking framework ba...To address the issues of frequent identity switches(IDs)and degraded identification accuracy in multi object tracking(MOT)under complex occlusion scenarios,this study proposes an occlusion-robust tracking framework based on face-pedestrian joint feature modeling.By constructing a joint tracking model centered on“intra-class independent tracking+cross-category dynamic binding”,designing a multi-modal matching metric with spatio-temporal and appearance constraints,and innovatively introducing a cross-category feature mutual verification mechanism and a dual matching strategy,this work effectively resolves performance degradation in traditional single-category tracking methods caused by short-term occlusion,cross-camera tracking,and crowded environments.Experiments on the Chokepoint_Face_Pedestrian_Track test set demonstrate that in complex scenes,the proposed method improves Face-Pedestrian Matching F1 area under the curve(F1 AUC)by approximately 4 to 43 percentage points compared to several traditional methods.The joint tracking model achieves overall performance metrics of IDF1:85.1825%and MOTA:86.5956%,representing improvements of 0.91 and 0.06 percentage points,respectively,over the baseline model.Ablation studies confirm the effectiveness of key modules such as the Intersection over Area(IoA)/Intersection over Union(IoU)joint metric and dynamic threshold adjustment,validating the significant role of the cross-category identity matching mechanism in enhancing tracking stability.Our_model shows a 16.7%frame per second(FPS)drop vs.fairness of detection and re-identification in multiple object tracking(FairMOT),with its cross-category binding module adding aboute 10%overhead,yet maintains near-real-time performance for essential face-pedestrian tracking at small resolutions.展开更多
Rock mass stability is significantly influenced by the heterogeneity of rock joint roughness and shear strength.While modern technology facilitates assessing roughness heterogeneity,evaluating shear strength heterogen...Rock mass stability is significantly influenced by the heterogeneity of rock joint roughness and shear strength.While modern technology facilitates assessing roughness heterogeneity,evaluating shear strength heterogeneity remains challenging.To address this,this study first captures the morphology of large-scale(1000 mm × 1000 mm) slate and granite joints via 3D laser scanning.Analysis of these surfaces and corresponding push/pull tests on carved specimens revealed a potential correlation between the heterogeneity of roughness and shear strength.A comparative evaluation of five statistical metrics identified information entropy(Hs) as the most robust indicator for quantifying rock joint heterogeneity.Further analysis using Hsreveals that the heterogeneity is anisotropic and,critically,that shear strength heterogeneity is governed not only by roughness heterogeneity but is also significantly influenced by the mean roughness value,normal stress,and intact rock tensile strength.Consequently,a simple comparison of roughness Hsvalues is insufficient for reliably comparing shear strength heterogeneity.To overcome this limitation,a theoretical framework is developed to explicitly map fundamental roughness statistics(mean and heterogeneity) to shear strength heterogeneity.This framework culminates in a practical workflow that allows for the rapid,field-based assessment of shear strength heterogeneity using readily obtainable rock joint roughness data.展开更多
The dissimilar 2B06 and 7B04 Al alloy joints were prepared by refill friction stir spot welding(RFSSW),and the microstructural evolution and corrosion behavior of the joints were investigated.Based on microstructural ...The dissimilar 2B06 and 7B04 Al alloy joints were prepared by refill friction stir spot welding(RFSSW),and the microstructural evolution and corrosion behavior of the joints were investigated.Based on microstructural analysis,the welded joints exhibit distinct microstructural zones,including the stir zone(SZ),thermomechanically affected zone(TMAZ),and heat-affected zone(HAZ).The grain size of each zone is in the order of HAZ>TMAZ>SZ.Notably,the TMAZ and HAZ contain significantly larger secondary-phase particles compared to the SZ,with particle size in the HAZ increasing at higher rotational speeds.Electrochemical tests indicate that corrosion susceptibility follows the sequence of HAZ>TMAZ>SZ>BM,with greater sensitivity observed at increased rotational speeds.Post-corrosion mechanical performance degradation primarily arises from crevice corrosion at joint overlaps,but not from the changes in the microstructure.展开更多
As joint operations have become a key trend in modern military development,unmanned aerial vehicles(UAVs)play an increasingly important role in enhancing the intelligence and responsiveness of combat systems.However,t...As joint operations have become a key trend in modern military development,unmanned aerial vehicles(UAVs)play an increasingly important role in enhancing the intelligence and responsiveness of combat systems.However,the heterogeneity of aircraft,partial observability,and dynamic uncertainty in operational airspace pose significant challenges to autonomous collision avoidance using traditional methods.To address these issues,this paper proposes an adaptive collision avoidance approach for UAVs based on deep reinforcement learning.First,a unified uncertainty model incorporating dynamic wind fields is constructed to capture the complexity of joint operational environments.Then,to effectively handle the heterogeneity between manned and unmanned aircraft and the limitations of dynamic observations,a sector-based partial observation mechanism is designed.A Dynamic Threat Prioritization Assessment algorithm is also proposed to evaluate potential collision threats from multiple dimensions,including time to closest approach,minimum separation distance,and aircraft type.Furthermore,a Hierarchical Prioritized Experience Replay(HPER)mechanism is introduced,which classifies experience samples into high,medium,and low priority levels to preferentially sample critical experiences,thereby improving learning efficiency and accelerating policy convergence.Simulation results show that the proposed HPER-D3QN algorithm outperforms existing methods in terms of learning speed,environmental adaptability,and robustness,significantly enhancing collision avoidance performance and convergence rate.Finally,transfer experiments on a high-fidelity battlefield airspace simulation platform validate the proposed method's deployment potential and practical applicability in complex,real-world joint operational scenarios.展开更多
BACKGROUND In an era leaning toward a personalized alignment of total knee arthroplasty,coronal plane alignment of the knee(CPAK)phenotypes for each population are studied;furthermore,other possible variables affectin...BACKGROUND In an era leaning toward a personalized alignment of total knee arthroplasty,coronal plane alignment of the knee(CPAK)phenotypes for each population are studied;furthermore,other possible variables affecting the alignment,such as ankle joint alignment,should be considered.AIM To determine CPAK distribution in the North African(Egyptian)population with knee osteoarthritis and to assess ankle joint line orientation(AJLO)adaptations across different CPAK types.METHODS A cross-sectional study was conducted on patients with primary knee osteoarthritis and normal ankle joints.Radiographic parameters included the mechanical lateral distal femoral angle,medial proximal tibial angle,and the derived calculations of joint line obliquity(JLO)and arithmetic hip-knee-ankle angle(aHKA).The tibial plafond horizontal angle(TPHA)was used for AJLO assessment,where 0°is neutral(type N),<0°is varus(type A),and>0°is valgus(type B).The nine CPAK types were further divided into 27 subtypes after incorporating the three AJLO types.RESULTS A total of 527 patients(1054 knees)were included for CPAK classification,and 435 patients(870 knees and ankles)for AJLO assessment.The mean age was 57.2±7.8 years,with 79.5%females.Most knees(76.4%)demonstrated varus alignment(mean aHKA was-5.51°±4.84°)and apex distal JLO(55.3%)(mean JLO was 176.43°±4.53°).CPAK types I(44.3%),IV(28.6%),and II(10%)were the most common.Regarding AJLO,70.2%of ankles exhibited varus orientation(mean TPHA was-5.21°±6.45°).The most frequent combined subtypes were CPAK type I-A(33.7%),IV-A(21.5%),and I-N(6.9%).A significant positive correlation was found between the TPHA and aHKA(r=0.40,P<0.001).CONCLUSION In this North African cohort,varus knee alignment with apex distal JLO and varus AJLO predominated.CPAK types I,IV,and II were the most common types,while subtypes I-A,IV-A,and I-N were commonly occurring after incorporating AJLO types;furthermore,the AJLO was significantly correlated to aHKA.展开更多
The existence of the"stomach-knee axis"and the potential independent association between"Helicobacter pylori(Hp)infection and knee osteoarthritis(KOA)"have been substantiated through multiple lines...The existence of the"stomach-knee axis"and the potential independent association between"Helicobacter pylori(Hp)infection and knee osteoarthritis(KOA)"have been substantiated through multiple lines of evidence,including epidemiological studies of the"stomach-knee axis",investigations into the pathological mechanisms linking"Hp infection and arthritis",as well as research on co-treatment drugs and the anti-inflammatory mechanisms relevant to"gastritis and arthritis".The investigation into"stomach and knee joint treatment"is grounded in the concept that the"stomach-knee axis"aligns with the"combined bi of body constituents and zang organs"theory.Clinical cases have demonstrated that therapeutic strategies of"stomach and knee joint treatment"can mitigate KOA damage by modulating the"stomach-knee axis"and eradicating Hp infection in the stomach.This study aims to contribute novel insights into the cross-system treatment of KOA.Further investigation into the"stomach-knee axis"may yield innovative strategies for the prevention and management of KOA,potentially through the eradication of Hp.展开更多
Rocks encountered in foundations of heavy structures are invariably intersected by discontinuities(joints).In the past,several studies have been performed by researchers to incorporate the effect of fully persistent j...Rocks encountered in foundations of heavy structures are invariably intersected by discontinuities(joints).In the past,several studies have been performed by researchers to incorporate the effect of fully persistent joints in the assessment of the load-carrying capacity of rocks.However,in the field,the joints are non-persistent,and an assumption of full persistency will underestimate the capacity.Recently,Shaunik&Singh have studied the influence of non-persistency,number of joint segments and discontinuity orientation on the strength behaviour of rock specimens(Shaunik and Singh,2019).Bell’s approach can be used to obtain the bearing capacity of shallow foundations placed in jointed rocks.In the present study,results of the experimental work(Shaunik and Singh,2019)conducted by Shaunik&Singh have been used to suggest expressions by extending Bell’s approach for computing bearing capacity of the foundation placed near the crown of a rock slope.Easy to use design charts are also presented for field application.Finally,a real-life problem from Indian Garhwal Himalayas is considered,and the approach suggested in this study is utilised to obtain the bearing capacity of a bridge foundation as a function of uniaxial compressive strength(UCS)of intact rock,joint friction,spacing and orientation of joint,nonpersistency and number of joint segments.展开更多
In this study, based on daily gage precipitation data of 2480 stations from 1961 to 2016, the summer （JuneeAugust） extreme precipitationevent was defined using the 95th percentile, and the changes in persistent （la...In this study, based on daily gage precipitation data of 2480 stations from 1961 to 2016, the summer （JuneeAugust） extreme precipitationevent was defined using the 95th percentile, and the changes in persistent （last for at least 2 d） and non-persistent （1 d） extreme precipitation inChina were analyzed. The results indicate that under global warming, the contribution of extreme precipitation to total summer precipitationincreased in most areas of China, but it decreased in the central part of Inner Mongolia and the Sichuan Basin. In North and Southwest China,both persistent and non-persistent extreme precipitation decreased; the decreasing trend of persistent extreme precipitation was more prominent;thus, extreme precipitation event occurred more as non-persistent event. Meanwhile, in the Yangtze River Basin and South China, both types ofextreme precipitation increased particularly the persistent extreme precipitation; persistent extreme precipitation occurred more compared withnon-persistent events.展开更多
AIM： TO estimate the prevalence of the lactase non-persistent genotype （C/C-23910） in a northern Russian population in accordance with ethnicity, and to evaluate self-reported milk consumption depending on lactase ...AIM： TO estimate the prevalence of the lactase non-persistent genotype （C/C-23910） in a northern Russian population in accordance with ethnicity, and to evaluate self-reported milk consumption depending on lactase activity. METHODS： Blood samples for genotyping lactase activity, defining the C/T-13910 variant by polymerase chain reaction, and direct sequencing were taken from 231 medical students of Russian origin aged 17-26 years. We analyzed milk product consumption by questionnaire which was specially designed for the estimation of milk consumption and abdominal complaints. RESULTS： We found that the prevalence of the C/C-13190 genotype in the northern Russian population was 35.6%. The other genotypes nearby C/T-13910 and associated with lactase activity were not present in the study population. The consumption of milk among people with the non-persistent genotype tended to be lower than among the lactose tolerant subjects, but was not statistically significant. CONCLUSION： An investigation of the lactase persistent genotype in a northern Russian population has not been performed before, The genotype did not affect the consumption of milk products in this population which could be explained by low consumption of milk products among the entire study population.展开更多
When the geological environment of rock masses is disturbed,numerous non-persisting open joints can appear within it.It is crucial to investigate the effect of open joints on the mechanical properties of rock mass.How...When the geological environment of rock masses is disturbed,numerous non-persisting open joints can appear within it.It is crucial to investigate the effect of open joints on the mechanical properties of rock mass.However,it has been challenging to generate realistic open joints in traditional experimental tests and numerical simulations.This paper presents a novel solution to solve the problem.By utilizing the stochastic distribution of joints and an enhanced-fractal interpolation system(IFS)method,rough curves with any orientation can be generated.The Douglas-Peucker algorithm is then applied to simplify these curves by removing unnecessary points while preserving their fundamental shape.Subsequently,open joints are created by connecting points that move to both sides of rough curves based on the aperture distribution.Mesh modeling is performed to construct the final mesh model.Finally,the RB-DEM method is applied to transform the mesh model into a discrete element model containing geometric information about these open joints.Furthermore,this study explores the impacts of rough open joint orientation,aperture,and number on rock fracture mechanics.This method provides a realistic and effective approach for modeling and simulating these non-persisting open joints.展开更多
Purpose–The bridge expansion joint(BEJ)is a key device for accommodating spatial displacement at the beam end,and for providing vertical support for running trains passing over the gap between the main bridge and the...Purpose–The bridge expansion joint(BEJ)is a key device for accommodating spatial displacement at the beam end,and for providing vertical support for running trains passing over the gap between the main bridge and the approach bridge.For long-span railway bridges,it must also be coordinated with rail expansion joint(REJ),which is necessary to accommodate the expansion and contraction of,and reducing longitudinal stress in,the rails.The main aim of this study is to present analysis of recent developments in the research and application of BEJs in high-speed railway(HSR)long-span bridges in China,and to propose a performance-based integral design method for BEJs used with REJs,from both theoretical and engineering perspectives.Design/methodology/approach–The study first presents a summary on the application and maintenance of BEJs in HSR long-span bridges in China representing an overview of their state of development.Results of a survey of typical BEJ faults were analyzed,and field testing was conducted on a railway cable-stayed bridge in order to obtain information on the major mechanical characteristics of its BEJ under train load.Based on the above,a performance-based integral design method for BEJs with maximum expansion range 1600 mm(±800 mm),was proposed,covering all stages from overall conceptual design to consideration of detailed structural design issues.The performance of the novel BEJ design thus derived was then verified via theoretical analysis under different scenarios,full-scale model testing,and field testing and commissioning.Findings–Two major types of BEJs,deck-type and through-type,are used in HSR long-span bridges in China.Typical BEJ faults were found to mainly include skewness of steel sleepers at the bridge gap,abnormally large longitudinal frictional resistance,and flexural deformation of the scissor mechanisms.These faults influence BEJ functioning,and thus adversely affect track quality and train running performance at the beam end.Due to their simple and integral structure,deck-type BEJs with expansion range 1200 mm(±600 mm)or less have been favored as a solution offering improved operational conditions,and have emerged as a standard design.However,when the expansion range exceeds the above-mentioned value,special design work becomes necessary.Therefore,based on engineering practice,a performance-based integral design method for BEJs used with REJs was proposed,taking into account four major categories of performance requirements,i.e.,mechanical characteristics,train running quality,durability and insulation performance.Overall BEJ design must mainly consider component strength and the overall stiffness of BEJ;the latter factor in particular has a decisive influence on train running performance at the beam end.Detailed BEJ structural design must stress minimization of the frictional resistance of its sliding surface.The static and dynamic performance of the newlydesigned BEJ with expansion range 1600 mm have been confirmed to be satisfactory,via numerical simulation,full-scale model testing,and field testing and commissioning.Originality/value–This research provides a broad overview of the status of BEJs with large expansion range in HSR long-span bridges in China,along with novel insights into their design.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.41825018)the Second Tibetan Plateau Scientific Expedition and Research Program(STEP)(Grant No.2019QZKK0904).
文摘Discontinuities are often considered as important factors responsible for the instability caused by shear failure in engineering rock mass,and energy-driven instability is the root cause of rock failure.However,few studies focus on the energy evolution during the failure process using a three-dimensional(3D)numerical model.In this study,a series of laboratory direct shear tests on rock-like samples is numer-ically simulated using bonded particle models(BPMs)with multiple combinations of discontinuous in the particle flow code(PFC3D),in which the location and size of the particles conform to the uniform distribution.The effects of joint row number and inclination on the stress-strain characteristics and failure mode of rock were studied from the perspective of microcrack growth and energy evolution.The results showed that,when the number of joint rows Nr>1,the shear failure region does not change with the increase of Nr for the type B(2-columnn multiple-row at center)and the type C(2-column multiple-row at edge)as compared to the type A(1-column multiple-row at center)joint models.Notably,joints significantly increase the post-peak energy dissipation but have little effect on the proportion of energy before the peak.Friction consumes most of the energy while kinetic energy accounts for less than 1%of total energy during the shear process.Peak elastic strain energy follows the variation trend of peak shear displacement.The development and accumulation of microcracks directly affect the energy dissipation,and there is a significant linear relationship between the cumulative number of critical microcracks and the critical dissipated energy at the failure,when the dip direction of joints is opposite to the shear direction,more microcracks will be accumulated at the peak time,resulting in more energy dissipation.The results contribute to deeply understanding the shear failure process of non-persistent jointed mass.
文摘Several constructions in the field of civil engineering quite often need to deal with rocks.Strength behaviour of rock intersected by a discontinuity or a set of discontinuities has been a topic of keen interest for engineering community.The popular attributes of discontinuities that have been given due importance are their frequency,orientation and surface characteristics.Non-persistency,however,has been given little attention.This article presents an experimental study wherein focus has been made on the effect of non-persistency of the joint on the uniaxial compressive strength(UCS)of a model rock for various geometries such as orientation,discontinuity length ratio and number of joint segments.The applicability of single plane of weakness theory(SPWT)to assess the strength of jointed specimens has also been evaluated.It has been noticed that SPWT captures the strength behaviour only for a narrow range of discontinuity orientations.As an improvement,an approach is suggested by extending concepts of degree of persistence and joint factor to have a better understanding towards strength behaviour of rocks intersected by non-persistent joints.
基金Project(2013CB036003)supported by the National Basic Research Program of ChinaProjects(51374198,51134001,51404255)supported by the National Natural Science Foundation of ChinaProject(BK20150005)supported by the Natural Science Foundation of Jiangsu Province for Distinguished Youth Scholar,China
文摘The stability of underground excavations is influenced by discontinuities interspaced in surrounding rock masses as well as the stress condition. In this work, a numerical study was undertaken on the failure behavior around a circular opening in a rock mass having non-persistent open joints using PFC software package. A parallel-bond stress corrosion(PSC) approach was incorporated to drive the failure of rock mass around the circular opening, such that the whole progressive failure process after excavation was reproduced. Based on the determined micro parameters for intact material and joint segments, the failure process around the circular opening agrees very well with that obtained through laboratory experiment. A subsequent parametric study was then carried out to look into the influence of lateral pressure coefficient, joint dip angle and joint persistency on the failure pattern and crack evolution of the rock mass around the circular opening. Three failure patterns identified are step path failure, planar failure and rotation failure depending on the lateral pressure coefficient. Moreover, the increment of joint dip angle and joint persistency aggravates the rock mass failure around the opening. This study offers guideline on stability estimation of underground excavations.
基金supported by the National Basic Research Program of China (No.2013CB036003)the Graduate Research and Innovation Program of Jiangsu Province (No.CXLX13_943)
文摘Pre-existing discontinuities change the mechanical properties of rock masses,and further influence failure behavior around an underground opening.In present study,the failure behavior in both Inner and Outer zones around a circular opening in a non-persistently jointed rock mass under biaxial compression was investigated through numerical simulations.First,the micro parameters of the PFC^(3D) model were carefully calibrated using the macro mechanical properties determined in physical experiments implemented on jointed rock models.Then,a parametrical study was undertaken of the effect of stress condition,joint dip angle and joint persistency.Under low initial stress,the confining stress improves the mechanical behavior of the surrounding rock masses;while under high initial stress,the surrounding rock mass failed immediately following excavation.At small dip angles the cracks around the circular opening developed generally outwards in a step-path failure pattern;whereas,at high dip angles the surrounding rock mass failed in an instantaneous intact rock failure pattern.Moreover,the stability of the rock mass around the circular opening deteriorated significantly with increasing joint persistency.
基金supported by the National Natural Science Foundation of China(Grant Nos.42372326 and 42090054)supported by the State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Independent Research Project(SKLGP2023Z015).
文摘During the excavation of large-scale rock slopes and deep hard rock engineering,the induced rapid unloading serves as the primary cause of rock mass deformation and failure.The essence of this phenomenon lies in the opening-shear failure process triggered by the normal stress unloading of fractured rock mass.In this study,we focus on local-scale rock fracture and conduct direct shear tests under different normal stress unloading rates on five types of non-persistent fractured hard rocks.The aim is to analyze the influence of normal stress unloading rates on the failure modes and shear mechanical characteristics of non-persistent fractured rocks.The results indicate that the normal unloading displacement decreases gradually with increasing normal stress unloading rate,while the influence of normal stress unloading rate on shear displacement is not significant.As the normal stress unloading rate increases,the rocks brittle failure process accelerates,and the degree of rocks damage decreases.Analysis of the stress state on rock fracture surfaces reveals that increasing the normal stress unloading rate enhances the compressive stress on rocks,leading to a transition in the failure mode from shear failure to tensile failure.A negative exponential strength formula was proposed,which effectively fits the relationship between failure normal stress and normal stress unloading rate.The findings enrich the theoretical foundation of unloading rock mechanics and provide theoretical support for disasters prevention and control in rock engineering excavations.
基金supported by the Hunan Science and Technology Innovation Plan(No.2024RC3015)the National Natural Science Foundation of China(No.22501053)+1 种基金National Key Research and Development Program(Nos.2022YFC3900902 and 2024YFC3907900)Major Science and Technology Projects of Yunnan Province(No.202302AB080016).
文摘The structural principles of traditional Chinese mortise-and-tenon joints have inspired breakthroughs in supramolecular engineering.Nevertheless,substantial challenges remain in constructing nanoscale supramolecular architectures with precisely controlled giant dimensions.Herein,we report a precision-guided synthetic strategy for constructing giant 2D and 3D supramolecular architectures with rhomboidal motifs,which was achieved through a dovetail joint strategy.Initial assembly of bis-mortise ligand L1 with dovetail tenon ligand L2 in the presence of Cd^(2+)ions yielded the fundamental bis-rhombic supramolecule R1.Subsequent structural elaboration of the dovetail tenon motif enabled the development of multitopic ligands L3 and L4,which facilitated the construction of expanded architectures of the giant bis-propeller supramolecule R2 and tris-propeller supramolecule R3.The synthesized supramolecules R1-R3 were fully characterized multidimensional NMR spectroscopy,electrospray ionization mass spectrometry(ESI-MS),traveling wave ion mobility mass spectrometry(TWIM-MS),transmission electron microscopy(TEM),and atomic force microscopy(AFM).This work develops an innovative dovetail-joint assembly strategy for constructing rigid giant supramolecular architectures,establishing a new paradigm for precision engineering of complex 3D molecular systems.
文摘With the intensification of population aging,knee and hip joint replacement surgeries have become core methods for treating end-stage joint diseases,with over a million cases performed globally each year.Postoperative rehabilitation nursing,as a crucial aspect of enhancing surgical outcomes,reducing complications,and facilitating patients’return to normal life,has its scientific and effective protocols directly influencing patient prognosis.This article systematically reviews the core research findings on rehabilitation nursing after joint replacement surgery based on the concept of evidence-based medicine,aiming to provide references for the formulation of standardized and personalized rehabilitation nursing plans in clinical settings.
文摘[Objectives]To investigate the clinical effects of implementing structured phased rehabilitation training,in addition to conventional rehabilitation,on shoulder joint function and pain alleviation in patients with rotator cuff injuries managed conservatively.[Methods]Eighty patients diagnosed with rotator cuff injury were selected and randomly assigned to either the control group or the experimental group,each comprising 40 individuals.The control group received conventional rehabilitation treatment,whereas the experimental group underwent phased rehabilitation training in addition to the conventional treatment for 6 weeks.Assessments were conducted prior to treatment,6 weeks following treatment,and 8 weeks after the completion of treatment(follow-up period).The visual analogue scale(VAS)was employed to evaluate pain intensity,the Constant-Murley score was utilized to assess shoulder joint function,and the shoulder joint range of motion was measured.[Results]Prior to treatment,no statistically significant differences were observed between the two patient groups across all measured indicators(P>0.05).Following 6 weeks of treatment and throughout the follow-up period,both groups exhibited significant reductions in VAS scores compared to baseline measurements,alongside improvements in Constant-Murley scores and shoulder joint range of motion(P<0.05).Furthermore,the magnitude of improvement in the experimental group was significantly greater than that in the control group(P<0.05).[Conclusions]Phased rehabilitation training can enhance shoulder joint function and alleviate pain in patients with rotator cuff injuries beyond the effects of conventional rehabilitation treatment,demonstrating notable clinical application value.
基金Supported by The Central Public-Interest Scientific Institution Basal Research Fund,CAFS(2025XT0902)Earmarked for China Agriculture Research System(CARS-46).
文摘The widespread use of herbicides such as glyphosate isopropyl amine salt(GIS)and atrazine(ATZ)poses significant risks to aquatic ecosystems.This study investigated the single and joint acute toxicity of a 1:1 GIS-ATZ mixture on zebrafish(Danio rerio).Acute tests determined 96-h LC_(50) values of 123.41 mg/L for GIS and 103.95 mg/L for ATZ.In the joint toxicity test,these values decreased to 60.96 and 50.88 mg/L,respectively.The Additive Index(AI)analysis revealed a consistent synergistic interaction between the herbicides at all exposure intervals.These findings underscore the enhanced ecological threat of herbicide mixtures and highlight the necessity of considering joint effects in environmental risk assessments.
基金supported by the confidential research grant No.a8317。
文摘To address the issues of frequent identity switches(IDs)and degraded identification accuracy in multi object tracking(MOT)under complex occlusion scenarios,this study proposes an occlusion-robust tracking framework based on face-pedestrian joint feature modeling.By constructing a joint tracking model centered on“intra-class independent tracking+cross-category dynamic binding”,designing a multi-modal matching metric with spatio-temporal and appearance constraints,and innovatively introducing a cross-category feature mutual verification mechanism and a dual matching strategy,this work effectively resolves performance degradation in traditional single-category tracking methods caused by short-term occlusion,cross-camera tracking,and crowded environments.Experiments on the Chokepoint_Face_Pedestrian_Track test set demonstrate that in complex scenes,the proposed method improves Face-Pedestrian Matching F1 area under the curve(F1 AUC)by approximately 4 to 43 percentage points compared to several traditional methods.The joint tracking model achieves overall performance metrics of IDF1:85.1825%and MOTA:86.5956%,representing improvements of 0.91 and 0.06 percentage points,respectively,over the baseline model.Ablation studies confirm the effectiveness of key modules such as the Intersection over Area(IoA)/Intersection over Union(IoU)joint metric and dynamic threshold adjustment,validating the significant role of the cross-category identity matching mechanism in enhancing tracking stability.Our_model shows a 16.7%frame per second(FPS)drop vs.fairness of detection and re-identification in multiple object tracking(FairMOT),with its cross-category binding module adding aboute 10%overhead,yet maintains near-real-time performance for essential face-pedestrian tracking at small resolutions.
基金supported by the National Natural Science Foundation of China (Nos.42422705,42207175,42177117 and 42577170)the Ningbo Youth Leading Talent Project (No.2024QL051)+1 种基金the Chinese Academy of Engineering Science and Technology Strategy Consulting Project (No.2025-XZ-57)the Central Government Funding Program for Guiding Local Science and Technology Development (No.2025ZY01028)。
文摘Rock mass stability is significantly influenced by the heterogeneity of rock joint roughness and shear strength.While modern technology facilitates assessing roughness heterogeneity,evaluating shear strength heterogeneity remains challenging.To address this,this study first captures the morphology of large-scale(1000 mm × 1000 mm) slate and granite joints via 3D laser scanning.Analysis of these surfaces and corresponding push/pull tests on carved specimens revealed a potential correlation between the heterogeneity of roughness and shear strength.A comparative evaluation of five statistical metrics identified information entropy(Hs) as the most robust indicator for quantifying rock joint heterogeneity.Further analysis using Hsreveals that the heterogeneity is anisotropic and,critically,that shear strength heterogeneity is governed not only by roughness heterogeneity but is also significantly influenced by the mean roughness value,normal stress,and intact rock tensile strength.Consequently,a simple comparison of roughness Hsvalues is insufficient for reliably comparing shear strength heterogeneity.To overcome this limitation,a theoretical framework is developed to explicitly map fundamental roughness statistics(mean and heterogeneity) to shear strength heterogeneity.This framework culminates in a practical workflow that allows for the rapid,field-based assessment of shear strength heterogeneity using readily obtainable rock joint roughness data.
基金supported by the National Natural Science Foundation of China (Nos. 52075449, 51975480)。
文摘The dissimilar 2B06 and 7B04 Al alloy joints were prepared by refill friction stir spot welding(RFSSW),and the microstructural evolution and corrosion behavior of the joints were investigated.Based on microstructural analysis,the welded joints exhibit distinct microstructural zones,including the stir zone(SZ),thermomechanically affected zone(TMAZ),and heat-affected zone(HAZ).The grain size of each zone is in the order of HAZ>TMAZ>SZ.Notably,the TMAZ and HAZ contain significantly larger secondary-phase particles compared to the SZ,with particle size in the HAZ increasing at higher rotational speeds.Electrochemical tests indicate that corrosion susceptibility follows the sequence of HAZ>TMAZ>SZ>BM,with greater sensitivity observed at increased rotational speeds.Post-corrosion mechanical performance degradation primarily arises from crevice corrosion at joint overlaps,but not from the changes in the microstructure.
基金supported by the National Key Research and Development Program of China(No.2022YFB4300902).
文摘As joint operations have become a key trend in modern military development,unmanned aerial vehicles(UAVs)play an increasingly important role in enhancing the intelligence and responsiveness of combat systems.However,the heterogeneity of aircraft,partial observability,and dynamic uncertainty in operational airspace pose significant challenges to autonomous collision avoidance using traditional methods.To address these issues,this paper proposes an adaptive collision avoidance approach for UAVs based on deep reinforcement learning.First,a unified uncertainty model incorporating dynamic wind fields is constructed to capture the complexity of joint operational environments.Then,to effectively handle the heterogeneity between manned and unmanned aircraft and the limitations of dynamic observations,a sector-based partial observation mechanism is designed.A Dynamic Threat Prioritization Assessment algorithm is also proposed to evaluate potential collision threats from multiple dimensions,including time to closest approach,minimum separation distance,and aircraft type.Furthermore,a Hierarchical Prioritized Experience Replay(HPER)mechanism is introduced,which classifies experience samples into high,medium,and low priority levels to preferentially sample critical experiences,thereby improving learning efficiency and accelerating policy convergence.Simulation results show that the proposed HPER-D3QN algorithm outperforms existing methods in terms of learning speed,environmental adaptability,and robustness,significantly enhancing collision avoidance performance and convergence rate.Finally,transfer experiments on a high-fidelity battlefield airspace simulation platform validate the proposed method's deployment potential and practical applicability in complex,real-world joint operational scenarios.
基金approved by Institutional Review Board of Faculty of Medicine in Assiut University,No.04-2024-300470.
文摘BACKGROUND In an era leaning toward a personalized alignment of total knee arthroplasty,coronal plane alignment of the knee(CPAK)phenotypes for each population are studied;furthermore,other possible variables affecting the alignment,such as ankle joint alignment,should be considered.AIM To determine CPAK distribution in the North African(Egyptian)population with knee osteoarthritis and to assess ankle joint line orientation(AJLO)adaptations across different CPAK types.METHODS A cross-sectional study was conducted on patients with primary knee osteoarthritis and normal ankle joints.Radiographic parameters included the mechanical lateral distal femoral angle,medial proximal tibial angle,and the derived calculations of joint line obliquity(JLO)and arithmetic hip-knee-ankle angle(aHKA).The tibial plafond horizontal angle(TPHA)was used for AJLO assessment,where 0°is neutral(type N),<0°is varus(type A),and>0°is valgus(type B).The nine CPAK types were further divided into 27 subtypes after incorporating the three AJLO types.RESULTS A total of 527 patients(1054 knees)were included for CPAK classification,and 435 patients(870 knees and ankles)for AJLO assessment.The mean age was 57.2±7.8 years,with 79.5%females.Most knees(76.4%)demonstrated varus alignment(mean aHKA was-5.51°±4.84°)and apex distal JLO(55.3%)(mean JLO was 176.43°±4.53°).CPAK types I(44.3%),IV(28.6%),and II(10%)were the most common.Regarding AJLO,70.2%of ankles exhibited varus orientation(mean TPHA was-5.21°±6.45°).The most frequent combined subtypes were CPAK type I-A(33.7%),IV-A(21.5%),and I-N(6.9%).A significant positive correlation was found between the TPHA and aHKA(r=0.40,P<0.001).CONCLUSION In this North African cohort,varus knee alignment with apex distal JLO and varus AJLO predominated.CPAK types I,IV,and II were the most common types,while subtypes I-A,IV-A,and I-N were commonly occurring after incorporating AJLO types;furthermore,the AJLO was significantly correlated to aHKA.
基金Supported by Discipline Construction Project of Shanxi University of Chinese Medicine—Internal Medicine of Traditional Chinese Medicine(2025XK02).
文摘The existence of the"stomach-knee axis"and the potential independent association between"Helicobacter pylori(Hp)infection and knee osteoarthritis(KOA)"have been substantiated through multiple lines of evidence,including epidemiological studies of the"stomach-knee axis",investigations into the pathological mechanisms linking"Hp infection and arthritis",as well as research on co-treatment drugs and the anti-inflammatory mechanisms relevant to"gastritis and arthritis".The investigation into"stomach and knee joint treatment"is grounded in the concept that the"stomach-knee axis"aligns with the"combined bi of body constituents and zang organs"theory.Clinical cases have demonstrated that therapeutic strategies of"stomach and knee joint treatment"can mitigate KOA damage by modulating the"stomach-knee axis"and eradicating Hp infection in the stomach.This study aims to contribute novel insights into the cross-system treatment of KOA.Further investigation into the"stomach-knee axis"may yield innovative strategies for the prevention and management of KOA,potentially through the eradication of Hp.
基金A part of this research was carried from financial assistance obtained from NRDMS Division Department of Science and Technology,New Delhithe assistance received from DST and thank for the support.
文摘Rocks encountered in foundations of heavy structures are invariably intersected by discontinuities(joints).In the past,several studies have been performed by researchers to incorporate the effect of fully persistent joints in the assessment of the load-carrying capacity of rocks.However,in the field,the joints are non-persistent,and an assumption of full persistency will underestimate the capacity.Recently,Shaunik&Singh have studied the influence of non-persistency,number of joint segments and discontinuity orientation on the strength behaviour of rock specimens(Shaunik and Singh,2019).Bell’s approach can be used to obtain the bearing capacity of shallow foundations placed in jointed rocks.In the present study,results of the experimental work(Shaunik and Singh,2019)conducted by Shaunik&Singh have been used to suggest expressions by extending Bell’s approach for computing bearing capacity of the foundation placed near the crown of a rock slope.Easy to use design charts are also presented for field application.Finally,a real-life problem from Indian Garhwal Himalayas is considered,and the approach suggested in this study is utilised to obtain the bearing capacity of a bridge foundation as a function of uniaxial compressive strength(UCS)of intact rock,joint friction,spacing and orientation of joint,nonpersistency and number of joint segments.
文摘In this study, based on daily gage precipitation data of 2480 stations from 1961 to 2016, the summer （JuneeAugust） extreme precipitationevent was defined using the 95th percentile, and the changes in persistent （last for at least 2 d） and non-persistent （1 d） extreme precipitation inChina were analyzed. The results indicate that under global warming, the contribution of extreme precipitation to total summer precipitationincreased in most areas of China, but it decreased in the central part of Inner Mongolia and the Sichuan Basin. In North and Southwest China,both persistent and non-persistent extreme precipitation decreased; the decreasing trend of persistent extreme precipitation was more prominent;thus, extreme precipitation event occurred more as non-persistent event. Meanwhile, in the Yangtze River Basin and South China, both types ofextreme precipitation increased particularly the persistent extreme precipitation; persistent extreme precipitation occurred more compared withnon-persistent events.
基金The Sigrid Jusélius Foundation,Helsinki,Finland and Tampere University Hospital Research Funds
文摘AIM： TO estimate the prevalence of the lactase non-persistent genotype （C/C-23910） in a northern Russian population in accordance with ethnicity, and to evaluate self-reported milk consumption depending on lactase activity. METHODS： Blood samples for genotyping lactase activity, defining the C/T-13910 variant by polymerase chain reaction, and direct sequencing were taken from 231 medical students of Russian origin aged 17-26 years. We analyzed milk product consumption by questionnaire which was specially designed for the estimation of milk consumption and abdominal complaints. RESULTS： We found that the prevalence of the C/C-13190 genotype in the northern Russian population was 35.6%. The other genotypes nearby C/T-13910 and associated with lactase activity were not present in the study population. The consumption of milk among people with the non-persistent genotype tended to be lower than among the lactose tolerant subjects, but was not statistically significant. CONCLUSION： An investigation of the lactase persistent genotype in a northern Russian population has not been performed before, The genotype did not affect the consumption of milk products in this population which could be explained by low consumption of milk products among the entire study population.
基金supported by the National Key R&D Program of China (2018YFC0407004)the Fundamental Research Funds for the Central Universities (Nos.B200201059,2021FZZX001-14)the National Natural Science Foundation of China (Grant No.51709089)and 111 Project.
文摘When the geological environment of rock masses is disturbed,numerous non-persisting open joints can appear within it.It is crucial to investigate the effect of open joints on the mechanical properties of rock mass.However,it has been challenging to generate realistic open joints in traditional experimental tests and numerical simulations.This paper presents a novel solution to solve the problem.By utilizing the stochastic distribution of joints and an enhanced-fractal interpolation system(IFS)method,rough curves with any orientation can be generated.The Douglas-Peucker algorithm is then applied to simplify these curves by removing unnecessary points while preserving their fundamental shape.Subsequently,open joints are created by connecting points that move to both sides of rough curves based on the aperture distribution.Mesh modeling is performed to construct the final mesh model.Finally,the RB-DEM method is applied to transform the mesh model into a discrete element model containing geometric information about these open joints.Furthermore,this study explores the impacts of rough open joint orientation,aperture,and number on rock fracture mechanics.This method provides a realistic and effective approach for modeling and simulating these non-persisting open joints.
基金National Key R&D Program of China(2022YFB2602900)R&D Fund Project of China Academy of Railway Sciences Corporation Limited(2021YJ084)+2 种基金Project of Science and Technology R&D Program of China Railway(2016G002-K)R&D Fund Project of China Railway Major Bridge Reconnaissance&Design Institute Co.,Ltd.(2021)R&D Fund Project of China Railway Shanghai Group(2021141).
文摘Purpose–The bridge expansion joint(BEJ)is a key device for accommodating spatial displacement at the beam end,and for providing vertical support for running trains passing over the gap between the main bridge and the approach bridge.For long-span railway bridges,it must also be coordinated with rail expansion joint(REJ),which is necessary to accommodate the expansion and contraction of,and reducing longitudinal stress in,the rails.The main aim of this study is to present analysis of recent developments in the research and application of BEJs in high-speed railway(HSR)long-span bridges in China,and to propose a performance-based integral design method for BEJs used with REJs,from both theoretical and engineering perspectives.Design/methodology/approach–The study first presents a summary on the application and maintenance of BEJs in HSR long-span bridges in China representing an overview of their state of development.Results of a survey of typical BEJ faults were analyzed,and field testing was conducted on a railway cable-stayed bridge in order to obtain information on the major mechanical characteristics of its BEJ under train load.Based on the above,a performance-based integral design method for BEJs with maximum expansion range 1600 mm(±800 mm),was proposed,covering all stages from overall conceptual design to consideration of detailed structural design issues.The performance of the novel BEJ design thus derived was then verified via theoretical analysis under different scenarios,full-scale model testing,and field testing and commissioning.Findings–Two major types of BEJs,deck-type and through-type,are used in HSR long-span bridges in China.Typical BEJ faults were found to mainly include skewness of steel sleepers at the bridge gap,abnormally large longitudinal frictional resistance,and flexural deformation of the scissor mechanisms.These faults influence BEJ functioning,and thus adversely affect track quality and train running performance at the beam end.Due to their simple and integral structure,deck-type BEJs with expansion range 1200 mm(±600 mm)or less have been favored as a solution offering improved operational conditions,and have emerged as a standard design.However,when the expansion range exceeds the above-mentioned value,special design work becomes necessary.Therefore,based on engineering practice,a performance-based integral design method for BEJs used with REJs was proposed,taking into account four major categories of performance requirements,i.e.,mechanical characteristics,train running quality,durability and insulation performance.Overall BEJ design must mainly consider component strength and the overall stiffness of BEJ;the latter factor in particular has a decisive influence on train running performance at the beam end.Detailed BEJ structural design must stress minimization of the frictional resistance of its sliding surface.The static and dynamic performance of the newlydesigned BEJ with expansion range 1600 mm have been confirmed to be satisfactory,via numerical simulation,full-scale model testing,and field testing and commissioning.Originality/value–This research provides a broad overview of the status of BEJs with large expansion range in HSR long-span bridges in China,along with novel insights into their design.
