Layered rock masses represent complex geological formations commonly encountered in the surrounding rock of deep engineering excavations(Hou et al.,2019;Xu et al.,2017;Yang C H et al.,2009;Xian and Tan,1989).These roc...Layered rock masses represent complex geological formations commonly encountered in the surrounding rock of deep engineering excavations(Hou et al.,2019;Xu et al.,2017;Yang C H et al.,2009;Xian and Tan,1989).These rock masses are predominantly composed of sedimentary,para-metamorphic,and volcanic rock types,characterized by a set of prominent,primary bedding structural planes(layers)exhibiting relatively consistent orientations and significant spatial continuity.展开更多
The Standard Model of particle physics assumes that fundamental fermions are point particles with zero radius, no spatial dimensions, and infinite matter density. This alternative model treats the nine charged fundame...The Standard Model of particle physics assumes that fundamental fermions are point particles with zero radius, no spatial dimensions, and infinite matter density. This alternative model treats the nine charged fundamental fermions (three leptons and nine quarks) as spheres with non-zero holographic radius. Holographic analysis (based on quantum mechanics, general relativity, thermodynamics, and Shannon information theory) specifies electron mass by five fundamental constants: Planck’s constant ℏ, gravitational constant G, fine structure constant α, cosmological constant Λ, and vacuum energy fraction ΩΛ. Protons and neutrons are composite systems of up and down quarks. Describing forces between quark constituents confined within nucleons as inverse square attractive forces, this alternative model identifies composition factors Cpand Cnto relate proton and neutron masses to electron mass and thus to fundamental constants. An appendix summarizes holographic analyses characterizing astronomical masses at the opposite end of the mass scale for objects in the universe.展开更多
Pediatric liver masses encompass a diverse spectrum of benign and malignant lesions,with distinct patterns based on patient age.Optimal imaging is critical for timely diagnosis,management,and prognosis.This pictorial ...Pediatric liver masses encompass a diverse spectrum of benign and malignant lesions,with distinct patterns based on patient age.Optimal imaging is critical for timely diagnosis,management,and prognosis.This pictorial minireview cate-gorizes pediatric liver masses by age group to guide hepatology and radiology practice,with an emphasis on imaging characteristics.In children from birth to six years of age,the most common liver masses include hepatoblastoma,the most common primary hepatic malignancy in this age group;infantile hemangioma,a benign vascular tumor with a characteristic appearance on imaging;and mesen-chymal hamartoma,a rare developmental lesion.For children older than six years,liver masses are distinct,with hepatocellular carcinoma being the predo-minant malignant lesion.Benign masses such as focal nodular hyperplasia and hepatocellular adenoma also emerge in this age range,often linked to hormonal influences or metabolic disorders.The masses observed across all pediatric age groups include hepatic cysts,choledochal cysts,hydatid cysts,pyogenic and amebic abscesses,tuberculosis,lymphoma,and metastases,each presenting with unique imaging features essential for differential diagnosis.This minireview provides a comprehensive,age-based overview of pediatric liver masses,focusing on clinical presentation and key imaging findings to support accurate diagnosis and optimize management strategies in clinical hepatology,particularly in low resource settings.展开更多
The compositions and distributions of monoterpenes,isoprene,aromatics and sesquiterpene SOA tracers(SOAM,SOAI,SOAA and SOAS,respectively)at an island site(Da Wan Shan Island,DWS)were investigated in the context of the...The compositions and distributions of monoterpenes,isoprene,aromatics and sesquiterpene SOA tracers(SOAM,SOAI,SOAA and SOAS,respectively)at an island site(Da Wan Shan Island,DWS)were investigated in the context of the influence of continental and marine air masses over the Pearl River Estuary(PRE)region in winter 2021.The sum concentration of SOA tracers was 6.2–132.8 ng m^(−3),with SOAM and SOAI as the main components in both continental(scenarios A1 and A2)and marine air masses(scenario A3),as well as their combination(scenario A4).The highest and lowest levels of SOAM were observed in A1 and A3,respectively,which were mainly related to the variations in meteorological conditions,precursor concentrations,and the degree of photochemical processes.Higher MBTCA/HGA(3-methyl-1,2,3-butanetricarboxylic acid/3-hydroxyglutaric acid)ratios suggested a less significant contribution fromα-pinene to SOAM.The variations of SOAI in the different scenarios were associated with differences in relative humidity,particle acidity,and isoprene/NOx ratios.The respective highest and lowest concentrations of aromatics SOA tracers in A1 and A3 revealed the influence of anthropogenic precursors from upwind continental areas,which was confirmed by the correlation among biogenic and anthropogenic precursors.The results of the tracer-based-method suggested dominant contributions of SOAs from aromatics and monoterpenes,with the highest concentrations in A1.A WRF-Chem simulation revealed that the SOAs from the above precursors only contributed 12%–25%to the total SOA at DWS,while the spatial distributions of SOAs further highlighted that the abundance of SOAs over the PRE region in winter is highly associated with air masses transported from upwind continental areas.展开更多
Cystic lesions of the anterior mediastinum in children suggest a well-known group of benign lesions that are comparatively frequent.Thymic cysts(TCs)are mostly positioned in the anterior mediastinum and some patients ...Cystic lesions of the anterior mediastinum in children suggest a well-known group of benign lesions that are comparatively frequent.Thymic cysts(TCs)are mostly positioned in the anterior mediastinum and some patients in the neck.Benign TCs classified as congenital intra-thoracic mesothelial cysts are commonly asymptomatic and have slight clinical significance.Multilocular TC,which can mimic another anterior mediastinal cystic tumor and is seen in adults,is more clinically important.It is a sporadic mediastinal lesion thought to arise in the course of acquired inflammation.Congenital mediastinal cysts represent 3%-6%of all mediastinal tumors and 10%-18%of radiologically reported mediastinal masses.Mediastinal TCs are uncommon and it is hard to know their true incidence.About 60%of cases with mediastinal TCs are asymptomatic,and the remainder of patients complains of nonspecific symptoms(e.g.,chest pain,dyspnea,or cough).The literature suggests that most cysts are benign,but an indefinite percentage may have a neoplastic process and result in significant compressive symptoms over time.Clinical symptoms of TCs vary depending on the location.In addition,frequent symptoms at the appearance of enlarged benign thymic and mediastinal cysts generally contain compressive symptoms(e.g.,respiratory distress,thymic pain,and symptoms related to Horner syndrome,hoarseness,dysphonia,dyspnea,orthopnea,wheezing,and fever).Many TCs have cystic density and a neat border and are simple to diagnose with radiological imaging.However,some TCs are hard to identify before surgery and may be misidentified as thymomas depending on their site and computed tomography results.Excision by thoracotomy,median sternotomy,or video-assisted techniques is essential for conclusive diagnosis,management,and abolition of relapse of anterior mediastinal masses and TCs.Histopathologic examination may be required after surgery.Considering the extent of the mass and the preliminary inability to make a definitive diagnosis,en bloc excision of the cyst was thought to be preferred to circumvent likely complications(e.g.,perforation,spillage of the contents,or incomplete excision).展开更多
Curtain grouting projects are characterized by their large scale and complexity,presenting significant challenges for real-time prediction of grout penetration using traditional methods.This study introduces an intell...Curtain grouting projects are characterized by their large scale and complexity,presenting significant challenges for real-time prediction of grout penetration using traditional methods.This study introduces an intelligent prediction method for grouting in fractured rock masses based on three core principles:integration of multi-source input features,fracture voxel modeling,and shortest path in sequential grouting.Three categories of data(geological structure data,grouting environmental data,and grouting operation data in the concept of a grouting geological model)are integrated and served as multi-source structured data in the intelligent prediction of grouting.A voxelization model quantifies the spatial characteristics of fractures,with voxel size optimized for capturing grouting paths.A shortest path algorithm based on a hierarchical solution is then developed to calculate grout penetration distances in the process of sequential grouting.A complete analysis framework is established,from the voxelization of the fracture network model to precise voxel classification,ultimately achieving an accurate prediction of grout penetration.The method demonstrates excellent performance on the test set,with validation against numerical methods in single-fracture and sequential grouting scenarios confirming its accuracy and prediction efficiency as hundreds of times faster than numerical methods.Application to the Dongzhuang hydraulic project’s grouting test area further validates its effectiveness in multi-hole grouting scenarios.展开更多
The property of water mass plays an important role in determining the distribution of phytoplankton in the ocean.In the Yellow Sea,summer stratification constrains water exchange and differentiates the properties of t...The property of water mass plays an important role in determining the distribution of phytoplankton in the ocean.In the Yellow Sea,summer stratification constrains water exchange and differentiates the properties of the Yellow Sea Cold Water Mass(YSCWM)and surface water,which in turn affects the spatiotemporal patterns of phytoplankton communities.Here,based on four summer cruises in the Yellow Sea,we examined the response of phytoplankton pigment assemblages to three water masses,including surface water(water massⅠ,WM-Ⅰ),thermocline water(WM-Ⅱ),and the YSCWM(WM-Ⅲ).Based on the opportunities for group dominance across the four cruises,Cyanophyceae,Haptophyceae,Chlorophyceae,and Cryptophyceae preferred living in WM-Ⅰ,characterized by relatively higher temperature and light intensity but lower nutrients;Bacillariophyceae,Chlorophyceae,Cyanophyceae,and Dinophyceae dominated in WM-Ⅲ,with relatively lower temperature and light intensity but higher nutrients.In comparison,the highest diversity of the dominant pigment groups was observed in WM-Ⅱ with intermediate temperature,light,and nutrient levels.The Dirichlet regression model identified the key environmental factors driving changes in phytoplankton assemblages in WM-Ⅰ,Ⅱ,and Ⅲ as dissolved inorganic phosphate(DIP),DIP and light,and temperature and ammonium,respectively.Under the impact of global environmental change,the fluctuations of key driving forces and their potential ecological implications need further investigation.展开更多
This study examines in-situ temperature profiles in three representative sections,namely,the Dalian-Chengshantou(DC),the Chengshantou-Changsangot(CC),and the 36°N,to delineate the interannual variations of the Ye...This study examines in-situ temperature profiles in three representative sections,namely,the Dalian-Chengshantou(DC),the Chengshantou-Changsangot(CC),and the 36°N,to delineate the interannual variations of the Yellow Sea Cold Water Mass(YSCWM)and investigate their potential connections,along with forcing factors,across different regions.The findings reveal the fol-lowing insights:1)The YSCWM experiences warming trends at DC,CC,and the western segment of the 36°N,revealing correspond-ing minimum temperature rates of 0.021℃/yr,0.043℃/yr,and 0.063℃/yr,respectively.Conversely,the eastern portion of the 36°N displays a slight cooling trend,resulting in a pronounced zonal disparity in long-term temperature trends.2)The changes in the YSCWM are closely linked to the atmospheric wind patterns.Notably,the weakening of northerly winds during winter corresponds to the rise in YSCWM temperature,which is accompanied by a westward shift in the cold core of the 36°N section.3)Correlation analysis with factors such as the Arctic Oscillation(AO),Pacific Decadal Oscillation(PDO),and El Niño-Southern Oscillation(EN-SO),etc.,indicates that changes in large-scale climate systems influence the spatiotemporal variations of the YSCWM,resulting in seasonal differences.展开更多
The special columnar jointed structure endows rocks with significant anisotropy,accurately grasping the strength and deformation properties of a columnar jointed rock mass(CJRM)under complex geological conditions is c...The special columnar jointed structure endows rocks with significant anisotropy,accurately grasping the strength and deformation properties of a columnar jointed rock mass(CJRM)under complex geological conditions is crucial for related engineering safety.Combined with the irregular jointed networks observed in the field,artificial irregular CJRM(ICJRM)samples with various inclination angles were prepared for triaxial tests.The results showed that the increase in confining pressure can enhance the ability of the ICJRM to resist deformation and failure,and reduce the deformation and strength anisotropic degrees.Considering the field stress situation,the engineering parts with an inclination angle of 30°−45°need to be taken seriously.Four typical failure modes were identified,and the sample with an inclination angle of 15°showed the same failure behavior as the field CJRM.Traditional and improved joint factor methods were used to establish empirical relationships for predicting the strength and deformation of CJRM under triaxial stress.Since the improved joint factor method can reflect the unique structure of CJRM,the predictive ability of the empirical relationship based on the improved method is better than that based on the traditional joint factor method.展开更多
The mechanical properties of jointed rock masses are critical to structural stability and durability.Advances in 3D printing and numerical simulations have facilitated innovative studies on their deformation and mecha...The mechanical properties of jointed rock masses are critical to structural stability and durability.Advances in 3D printing and numerical simulations have facilitated innovative studies on their deformation and mechanical behavior.However,the discontinuous and non-penetrating nature of rock joints presents challenges for predictive modeling.This study presents an computed tomography and synthetic rock mass(CT-SRM)integrated analytical approach to investigate the mechanical properties of non-persistent jointed coal measures,with three notable findings contributions:Firstly,a novel digital reconstruction methodology for joint networks was developed using high-precision CT scanning and 3D reconstruction techniques,achieving accuracy of 96.03%.Secondly,the research has identified the critical joint diameter effect(30 mm)causing 30%-50%strength reduction and observed wing-shaped deformation induced by 30°secondary joints,elucidating a new size-controlled mechanism.Thirdly,quantitative correlation models between joint geometric parameters and macroscopic mechanical properties were established,offering insights for engineering stability assessment.The developed analytical framework offers a reliable solution for stability prediction of jointed rock masses in engineering applications.展开更多
The rock masses in the hydro-fluctuation zone of reservoir banks sustain wettingdrying cycles(WDC),thereby affecting the stability of the reservoir bank slope.In this paper,rock masses with argillaceous siltstone and ...The rock masses in the hydro-fluctuation zone of reservoir banks sustain wettingdrying cycles(WDC),thereby affecting the stability of the reservoir bank slope.In this paper,rock masses with argillaceous siltstone and silty mudstone interbedded in Badong Formation were taken as the research object to investigate the variation of strength parameters of soft and hard interbedded rock masses with WDC and dip angle through laboratory experiments and numerical experiments.Some attempts were made to reveal the mechanical properties deterioration mechanism of interbedded rock masses by quantitatively analyzing the contribution of strength parameters deterioration of hard rocks,soft rocks,and bedding planes to the strength parameters deterioration of rock masses.The results indicate that the logarithmic function could be used to describe the deterioration of each strength parameter of both argillaceous siltstone and silty mudstone and bedding plane with the number of WDC.The strength parameters of interbedded rock masses decrease as the number of WDC increases,with the largest decrease after the first cycle and then slowing down in the later cycles.The strength parameters initially decrease and then increase as the dip angles increase.The impact of deteriorated strength parameters of bedding planes and rocks on the deterioration of strength parameters of interbedded rock masses differs significantly with the dip angle,which can be divided into four typical ranges of different controlling factors.展开更多
Face stability is an essential issue in tunnel design and construction.Layered rock masses are typical and ubiquitous;uncertainties in rock properties always exist.In view of this,a comprehensive method,which combines...Face stability is an essential issue in tunnel design and construction.Layered rock masses are typical and ubiquitous;uncertainties in rock properties always exist.In view of this,a comprehensive method,which combines the Upper bound Limit analysis of Tunnel face stability,the Polynomial Chaos Kriging,the Monte-Carlo Simulation and Analysis of Covariance method(ULT-PCK-MA),is proposed to investigate the seismic stability of tunnel faces.A two-dimensional analytical model of ULT is developed to evaluate the virtual support force based on the upper bound limit analysis.An efficient probabilistic analysis method PCK-MA based on the adaptive Polynomial Chaos Kriging metamodel is then implemented to investigate the parameter uncertainty effects.Ten input parameters,including geological strength indices,uniaxial compressive strengths and constants for three rock formations,and the horizontal seismic coefficients,are treated as random variables.The effects of these parameter uncertainties on the failure probability and sensitivity indices are discussed.In addition,the effects of weak layer position,the middle layer thickness and quality,the tunnel diameter,the parameters correlation,and the seismic loadings are investigated,respectively.The results show that the layer distributions significantly influence the tunnel face probabilistic stability,particularly when the weak rock is present in the bottom layer.The efficiency of the proposed ULT-PCK-MA is validated,which is expected to facilitate the engineering design and construction.展开更多
In this editorial we comment on the article by Huffaker et al,published in the current issue of the World Journal of Clinical Cases.Cardiac masses encompass a broad range of lesions,potentially involving any cardiac s...In this editorial we comment on the article by Huffaker et al,published in the current issue of the World Journal of Clinical Cases.Cardiac masses encompass a broad range of lesions,potentially involving any cardiac structure,and they can be either neoplastic or non-neoplastic.Primitive cardiac tumors are rare,while metastases and pseudotumors are relatively common.Cardiac masses frequently pose significant diagnostic and therapeutic challenges.Multimodality imaging is fundamental for differential diagnosis,treatment,and surgical planning.In particular cardiac magnetic resonance(CMR)is currently the gold standard for noninvasive tissue characterization.CMR allows evaluation of the relationship between the tumor and adjacent structures,detection of the degree of infiltration or expansion of the mass,and prediction of the possible malignancy of a mass with a high accuracy.Different flow charts of diagnostic work-up have been proposed,based on clinical,laboratory and imaging findings,with the aim of helping physicians approach the problem in a pragmatic way(“thinking inside the box”).However,the clinical complexity of cancer patients,in particular those with rare syndromes,requires a multidisciplinary approach and an open mind to go beyond flow charts and diagnostic algorithms,in other words the ability to“think outside the box”.展开更多
Lesions of the left triangular ligament of the liver are rare,and there are even fewer cases of vascular tumors misdiagnosed as gastrointestinal stromal tumors.We comment on the two cases reported in the article.The a...Lesions of the left triangular ligament of the liver are rare,and there are even fewer cases of vascular tumors misdiagnosed as gastrointestinal stromal tumors.We comment on the two cases reported in the article.The article did not include pictures of laparoscopic surgery,making it unconvincing.For gastric submucosal lesions,enhanced computed tomography venous phase imaging may be beneficial for differential diagnosis.Although endoscopic ultrasound is an effective tool for diagnosing submucosal lesions of the stomach,due to various factors,it cannot achieve an accurate diagnosis.During endoscopic examination,a more accurate diagnosis can be made depending on the personal experience of the operators.展开更多
The Standard Model of particle physics involves twelve fundamental fermions, treated as point particles, in four charge states. However, the Standard Model does not explain why only three fermions are in each charge s...The Standard Model of particle physics involves twelve fundamental fermions, treated as point particles, in four charge states. However, the Standard Model does not explain why only three fermions are in each charge state or account for neutrino mass. This holographic analysis treats charged Standard Model fermions as spheres with mass 0.187 g/cm<sup>2</sup> times their surface area, using the proportionality constant in the holographic relation between mass of the observable universe and event horizon radius. The analysis requires three Standard Model fermions per charge state and relates up quark and down quark masses to electron mass. Holographic analysis specifies electron mass, to six significant figures, in terms of fundamental constants α,ℏ,G,Λ and Ω Λ . Treating neutrinos as spheres and equating electron neutrino energy density with cosmic vacuum energy density predicts neutrino masses consistent with experiment.展开更多
Flexural toppling occurs when a series of layered rock masses bend towards their free face.It is important to evaluate the maximum bending degree and the requirement of supports of flexural toppling rock mass to preve...Flexural toppling occurs when a series of layered rock masses bend towards their free face.It is important to evaluate the maximum bending degree and the requirement of supports of flexural toppling rock mass to prevent rock mass cracking and even failure leading to a landslide.Based on the rock tensile strain-softening model,this study proposes a method for calculating the maximum curvature(C_(ppmax))of flexural toppling rock masses.By applying this method to calculate Cppmax of 9 types of rock masses with different hardness and rock layer thickness,some conclusions are drawn:(1)the internal key factors affecting C_(ppmax)are E^(⋆)(E^(⋆)=E_(ss)/E_(0),where E_(0)and E_(ss)are the mean deformation moduli of the rock before and after reaching its peak tensile strength,respectively),the strainεt corresponding to the tensile strength of rock,and the thickness(h)of rock layers;(2)hard rock layers are more likely to develop into block toppling than soft rock layers;and(3)thin rock layers are more likely to remain in flexural toppling state than thick rock layers.In addition,it is found that C_(ppmax)for flexural toppling rock masses composed of bedded rocks such as gneiss is related to the tensile direction.展开更多
Experiments on grouting-reinforced rock mass specimens with different particle sizes and features were carried out in this study to examine the effects of grouting reinforcement on the load-bearing characteristics of ...Experiments on grouting-reinforced rock mass specimens with different particle sizes and features were carried out in this study to examine the effects of grouting reinforcement on the load-bearing characteristics of fractured rock mass.The strength and deformation features of grouting-reinforced rock mass were analyzed under different loading manners;the energy evolution mechanism of grouting-reinforced rock mass specimens with different particle sizes and features was investigated;the energy dissipation ratio and post-peak stress decreasing rate were employed to evaluate the bearing stability of grouting-reinforced rock mass.The results show that the strength and ductility of granite-reinforced rock mass(GRM)under biaxial loading are higher than that of sandstone-reinforced rock mass(SRM)under uniaxial loading.Besides,the energy evolution characteristics of grouting-reinforced rock mass under uniaxial and biaxial loading mainly could be divided into early,middle,and late stages.In the early stage,total,elastic,and dissipation energies were quite small with flatter curves;in the middle stage,elastic energy increased rapidly,whereas dissipation energy increased slowly;in the late stage,dissipation energy increased sharply.The energy dissipation ratio was used to represent the pre-peak plastic deformation.Under uniaxial loading,this ratio increased as the particle size increased and the pre-peak plastic deformation of grouting-reinforced rock mass became larger;under biaxial loading,it dropped as the particle size increased,and the pre-peak plastic deformation of grouting-reinforced rock mass became smaller.The post-peak stress decline rate A_(v) was used to assess the post-peak bearing performance of grouting-reinforced rock mass.Under uniaxial loading,parameter A_(v) exhibited reduction as the particle size kept increasing,and the ability of post-peak of grouting-reinforced rock mass to allow deformation development was greater,and the bearing capacity was greater;under biaxial loading,A_(v) increased with the particle size,and the ability of post-peak of grouting-reinforced rock mass to allow deformation development was low and the bearing capacity was reduced.The findings are considered instrumental in improving the stability of the roadway-surrounding rock by granite and sandstone grouting.展开更多
The diagnostic approach to solid pancreatic masses has significantly evolved from the era when a focal pancreatic mass was almost synonymous to pancreatic ductal adenocarcinoma,to a wide spectrum of pancreatic lesions...The diagnostic approach to solid pancreatic masses has significantly evolved from the era when a focal pancreatic mass was almost synonymous to pancreatic ductal adenocarcinoma,to a wide spectrum of pancreatic lesions,some of which have good prognosis.With the advent of advanced diagnostic tools,particularly refined imaging and tissue acquisition techniques,a broader spectrum of differential diagnoses has been recognized,encompassing conditions ranging from neuroendocrine tumors or inflammatory masses,to rare entities like metastatic clear cell sarcoma or solitary fibrous tumors.We herein discuss case reports of some rare pancreatic lesions,which were diagnosed by combining clinical and imaging features and endoscopic ultrasound-guided tissue sampling and confirmed on surgical specimens.Further reports on these rare pancreatic tumors will contribute to a better understanding of their pathogenesis and effective management.展开更多
The method for precursor information acquisition based on acoustic emission(AE)data for jointed rock masses is of significant importance for the early warning of dynamic disasters in underground engineering.A clusteri...The method for precursor information acquisition based on acoustic emission(AE)data for jointed rock masses is of significant importance for the early warning of dynamic disasters in underground engineering.A clustering-convolutional neural network(CNN)method is proposed,which comprises a clustering component and a CNN component.A series of uniaxial compression tests were conducted on granite specimens containing a persistent sawtooth joint,with different strain rates(105e102 s1)and joint inclination angles(0e50).The results demonstrate that traditional precursory indicators based on full waveforms are effective for obtaining precursor information of the intact rock failure.However,these indicators are not universally applicable to the failure of rock masses with a single joint.The clustering-CNN method has the potential to be applied to obtain precursor information for all three failure modes(Modes I,II and III).Following the waveform clustering analysis,the effective waveforms exhibit a low main frequency,as well as high energy,ringing count,and rise time.Furthermore,the clustering method and the precursory indicators influence the acquisition of final precursor information.The Birch hierarchical clustering method and the S value precursory indicator can help to obtain more accurate results.The findings of this study may contribute to the development of warning methods for underground engineering across faults.展开更多
As one of the most common occurring geological landforms in deep rock formations, the dynamic mechanical properties of layered composite rock bodies under impact loading have been widely studied by scholars. To study ...As one of the most common occurring geological landforms in deep rock formations, the dynamic mechanical properties of layered composite rock bodies under impact loading have been widely studied by scholars. To study the dynamic properties of soft and hard composite rocks with different thickness ratios, this paper utilizes cement, quartz sand and gypsum powder to construct soft and hard composite rock specimens and utilizes a combination of indoor tests, numerical calculations, and theoretical analyses to investigate the mechanical properties of soft and hard composite rock bodies. The test results reveal that:(1) When the proportion of hard rock increases from 20% to 50%, the strength of the combined rock body increases by 69.14 MPa and 87 MPa when the hard rock face and soft rock face are loaded, respectively;however, when the proportion of hard rock is the same, the compressive strength of the hard rock face impact is 9%-17% greater than that of the soft rock face impact;(2) When a specimen of soft and hard combined rock body is subjected to impact loading, the damage mode involves mixed tension and shear damage, and the cracks generally first appear at the ends of the specimen, then develop on the laminar surface from the impact surface, and finally end in the overall damage of the soft rock part. The development rate and the total number of cracks in the same specimen when the hard rock face is impacted are significantly greater than those when the soft rock face is impacted;(3) By introducing Weibull’s statistical strength theory to establish the damage variables of soft-hard combined rock bodies, combined with the DP strength criterion, the damage model and the Kelvin body are concatenated to obtain a statistical damage constitutive model, which can better fit the full stress-strain curve of soft-hard combined rock body specimens under a single impact load.展开更多
基金supported by the National Natural Science Foundation of China(Nos.42107211 and U23A20651)the Natural Science Foundation of Sichuan Province(No.2025ZNSFSC0097)。
文摘Layered rock masses represent complex geological formations commonly encountered in the surrounding rock of deep engineering excavations(Hou et al.,2019;Xu et al.,2017;Yang C H et al.,2009;Xian and Tan,1989).These rock masses are predominantly composed of sedimentary,para-metamorphic,and volcanic rock types,characterized by a set of prominent,primary bedding structural planes(layers)exhibiting relatively consistent orientations and significant spatial continuity.
文摘The Standard Model of particle physics assumes that fundamental fermions are point particles with zero radius, no spatial dimensions, and infinite matter density. This alternative model treats the nine charged fundamental fermions (three leptons and nine quarks) as spheres with non-zero holographic radius. Holographic analysis (based on quantum mechanics, general relativity, thermodynamics, and Shannon information theory) specifies electron mass by five fundamental constants: Planck’s constant ℏ, gravitational constant G, fine structure constant α, cosmological constant Λ, and vacuum energy fraction ΩΛ. Protons and neutrons are composite systems of up and down quarks. Describing forces between quark constituents confined within nucleons as inverse square attractive forces, this alternative model identifies composition factors Cpand Cnto relate proton and neutron masses to electron mass and thus to fundamental constants. An appendix summarizes holographic analyses characterizing astronomical masses at the opposite end of the mass scale for objects in the universe.
文摘Pediatric liver masses encompass a diverse spectrum of benign and malignant lesions,with distinct patterns based on patient age.Optimal imaging is critical for timely diagnosis,management,and prognosis.This pictorial minireview cate-gorizes pediatric liver masses by age group to guide hepatology and radiology practice,with an emphasis on imaging characteristics.In children from birth to six years of age,the most common liver masses include hepatoblastoma,the most common primary hepatic malignancy in this age group;infantile hemangioma,a benign vascular tumor with a characteristic appearance on imaging;and mesen-chymal hamartoma,a rare developmental lesion.For children older than six years,liver masses are distinct,with hepatocellular carcinoma being the predo-minant malignant lesion.Benign masses such as focal nodular hyperplasia and hepatocellular adenoma also emerge in this age range,often linked to hormonal influences or metabolic disorders.The masses observed across all pediatric age groups include hepatic cysts,choledochal cysts,hydatid cysts,pyogenic and amebic abscesses,tuberculosis,lymphoma,and metastases,each presenting with unique imaging features essential for differential diagnosis.This minireview provides a comprehensive,age-based overview of pediatric liver masses,focusing on clinical presentation and key imaging findings to support accurate diagnosis and optimize management strategies in clinical hepatology,particularly in low resource settings.
基金supported by the State Key Program of the National Natural Science Foundation of China(Grant Nos.42230701,91644215)the National Natural ScienceFoundation of China(Grant Nos.42122062 and 42307137)+3 种基金the Guangdong Basic and Applied Basic Research Foundation(Grant No.2022A1515010852)the Fundamental Research Funds for the Central Universities,Sun Yat-sen University(Grant No.23hytd002)the Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)(Grant No.SML2023SP218)L.M.acknowledges the Zhuhai Science and Technology Plan Project(Grant No.ZH22036201210115PWC).
文摘The compositions and distributions of monoterpenes,isoprene,aromatics and sesquiterpene SOA tracers(SOAM,SOAI,SOAA and SOAS,respectively)at an island site(Da Wan Shan Island,DWS)were investigated in the context of the influence of continental and marine air masses over the Pearl River Estuary(PRE)region in winter 2021.The sum concentration of SOA tracers was 6.2–132.8 ng m^(−3),with SOAM and SOAI as the main components in both continental(scenarios A1 and A2)and marine air masses(scenario A3),as well as their combination(scenario A4).The highest and lowest levels of SOAM were observed in A1 and A3,respectively,which were mainly related to the variations in meteorological conditions,precursor concentrations,and the degree of photochemical processes.Higher MBTCA/HGA(3-methyl-1,2,3-butanetricarboxylic acid/3-hydroxyglutaric acid)ratios suggested a less significant contribution fromα-pinene to SOAM.The variations of SOAI in the different scenarios were associated with differences in relative humidity,particle acidity,and isoprene/NOx ratios.The respective highest and lowest concentrations of aromatics SOA tracers in A1 and A3 revealed the influence of anthropogenic precursors from upwind continental areas,which was confirmed by the correlation among biogenic and anthropogenic precursors.The results of the tracer-based-method suggested dominant contributions of SOAs from aromatics and monoterpenes,with the highest concentrations in A1.A WRF-Chem simulation revealed that the SOAs from the above precursors only contributed 12%–25%to the total SOA at DWS,while the spatial distributions of SOAs further highlighted that the abundance of SOAs over the PRE region in winter is highly associated with air masses transported from upwind continental areas.
文摘Cystic lesions of the anterior mediastinum in children suggest a well-known group of benign lesions that are comparatively frequent.Thymic cysts(TCs)are mostly positioned in the anterior mediastinum and some patients in the neck.Benign TCs classified as congenital intra-thoracic mesothelial cysts are commonly asymptomatic and have slight clinical significance.Multilocular TC,which can mimic another anterior mediastinal cystic tumor and is seen in adults,is more clinically important.It is a sporadic mediastinal lesion thought to arise in the course of acquired inflammation.Congenital mediastinal cysts represent 3%-6%of all mediastinal tumors and 10%-18%of radiologically reported mediastinal masses.Mediastinal TCs are uncommon and it is hard to know their true incidence.About 60%of cases with mediastinal TCs are asymptomatic,and the remainder of patients complains of nonspecific symptoms(e.g.,chest pain,dyspnea,or cough).The literature suggests that most cysts are benign,but an indefinite percentage may have a neoplastic process and result in significant compressive symptoms over time.Clinical symptoms of TCs vary depending on the location.In addition,frequent symptoms at the appearance of enlarged benign thymic and mediastinal cysts generally contain compressive symptoms(e.g.,respiratory distress,thymic pain,and symptoms related to Horner syndrome,hoarseness,dysphonia,dyspnea,orthopnea,wheezing,and fever).Many TCs have cystic density and a neat border and are simple to diagnose with radiological imaging.However,some TCs are hard to identify before surgery and may be misidentified as thymomas depending on their site and computed tomography results.Excision by thoracotomy,median sternotomy,or video-assisted techniques is essential for conclusive diagnosis,management,and abolition of relapse of anterior mediastinal masses and TCs.Histopathologic examination may be required after surgery.Considering the extent of the mass and the preliminary inability to make a definitive diagnosis,en bloc excision of the cyst was thought to be preferred to circumvent likely complications(e.g.,perforation,spillage of the contents,or incomplete excision).
基金supported by the National Natural Science Foundation of China(Grant No.U23A6018)Science and Technology Program of Hebei(Grant No.E2022202041,2022HBQZYCXY004,242Q9920Z)the project of“Key technologies of seepage control system for large-scale hydraulic projects”was also gratefully appreciated.
文摘Curtain grouting projects are characterized by their large scale and complexity,presenting significant challenges for real-time prediction of grout penetration using traditional methods.This study introduces an intelligent prediction method for grouting in fractured rock masses based on three core principles:integration of multi-source input features,fracture voxel modeling,and shortest path in sequential grouting.Three categories of data(geological structure data,grouting environmental data,and grouting operation data in the concept of a grouting geological model)are integrated and served as multi-source structured data in the intelligent prediction of grouting.A voxelization model quantifies the spatial characteristics of fractures,with voxel size optimized for capturing grouting paths.A shortest path algorithm based on a hierarchical solution is then developed to calculate grout penetration distances in the process of sequential grouting.A complete analysis framework is established,from the voxelization of the fracture network model to precise voxel classification,ultimately achieving an accurate prediction of grout penetration.The method demonstrates excellent performance on the test set,with validation against numerical methods in single-fracture and sequential grouting scenarios confirming its accuracy and prediction efficiency as hundreds of times faster than numerical methods.Application to the Dongzhuang hydraulic project’s grouting test area further validates its effectiveness in multi-hole grouting scenarios.
基金Supported by the National Natural Science Foundation of China(No.42030402)the Program of Shanghai Subject Chief Scientist(No.23XD1401200)collected onboard of R/Vs Dongfanghong 2 and Lanhai 101 implementing the open research cruises(Cruise Nos.NORC 2013-01,NORC 2015-01,NORC 2018-01,NORC 2021-01)supported by NSFC Shiptime Sharing Project(Nos.41249901,41449901,41749901,42049901)。
文摘The property of water mass plays an important role in determining the distribution of phytoplankton in the ocean.In the Yellow Sea,summer stratification constrains water exchange and differentiates the properties of the Yellow Sea Cold Water Mass(YSCWM)and surface water,which in turn affects the spatiotemporal patterns of phytoplankton communities.Here,based on four summer cruises in the Yellow Sea,we examined the response of phytoplankton pigment assemblages to three water masses,including surface water(water massⅠ,WM-Ⅰ),thermocline water(WM-Ⅱ),and the YSCWM(WM-Ⅲ).Based on the opportunities for group dominance across the four cruises,Cyanophyceae,Haptophyceae,Chlorophyceae,and Cryptophyceae preferred living in WM-Ⅰ,characterized by relatively higher temperature and light intensity but lower nutrients;Bacillariophyceae,Chlorophyceae,Cyanophyceae,and Dinophyceae dominated in WM-Ⅲ,with relatively lower temperature and light intensity but higher nutrients.In comparison,the highest diversity of the dominant pigment groups was observed in WM-Ⅱ with intermediate temperature,light,and nutrient levels.The Dirichlet regression model identified the key environmental factors driving changes in phytoplankton assemblages in WM-Ⅰ,Ⅱ,and Ⅲ as dissolved inorganic phosphate(DIP),DIP and light,and temperature and ammonium,respectively.Under the impact of global environmental change,the fluctuations of key driving forces and their potential ecological implications need further investigation.
文摘This study examines in-situ temperature profiles in three representative sections,namely,the Dalian-Chengshantou(DC),the Chengshantou-Changsangot(CC),and the 36°N,to delineate the interannual variations of the Yellow Sea Cold Water Mass(YSCWM)and investigate their potential connections,along with forcing factors,across different regions.The findings reveal the fol-lowing insights:1)The YSCWM experiences warming trends at DC,CC,and the western segment of the 36°N,revealing correspond-ing minimum temperature rates of 0.021℃/yr,0.043℃/yr,and 0.063℃/yr,respectively.Conversely,the eastern portion of the 36°N displays a slight cooling trend,resulting in a pronounced zonal disparity in long-term temperature trends.2)The changes in the YSCWM are closely linked to the atmospheric wind patterns.Notably,the weakening of northerly winds during winter corresponds to the rise in YSCWM temperature,which is accompanied by a westward shift in the cold core of the 36°N section.3)Correlation analysis with factors such as the Arctic Oscillation(AO),Pacific Decadal Oscillation(PDO),and El Niño-Southern Oscillation(EN-SO),etc.,indicates that changes in large-scale climate systems influence the spatiotemporal variations of the YSCWM,resulting in seasonal differences.
基金Projects(42307192,41831278)supported by the National Natural Science Foundation of ChinaProject(CKWV20231175/KY)supported by the CRSRI Open Research Program,China。
文摘The special columnar jointed structure endows rocks with significant anisotropy,accurately grasping the strength and deformation properties of a columnar jointed rock mass(CJRM)under complex geological conditions is crucial for related engineering safety.Combined with the irregular jointed networks observed in the field,artificial irregular CJRM(ICJRM)samples with various inclination angles were prepared for triaxial tests.The results showed that the increase in confining pressure can enhance the ability of the ICJRM to resist deformation and failure,and reduce the deformation and strength anisotropic degrees.Considering the field stress situation,the engineering parts with an inclination angle of 30°−45°need to be taken seriously.Four typical failure modes were identified,and the sample with an inclination angle of 15°showed the same failure behavior as the field CJRM.Traditional and improved joint factor methods were used to establish empirical relationships for predicting the strength and deformation of CJRM under triaxial stress.Since the improved joint factor method can reflect the unique structure of CJRM,the predictive ability of the empirical relationship based on the improved method is better than that based on the traditional joint factor method.
基金financially supported by the Hubei Province Key R&D Plan Project"Sliding Mechanism and Multi-indicator Linkage Process Prediction of Landslides in the West of Hubei Province"(No.2023BCB117)。
文摘The mechanical properties of jointed rock masses are critical to structural stability and durability.Advances in 3D printing and numerical simulations have facilitated innovative studies on their deformation and mechanical behavior.However,the discontinuous and non-penetrating nature of rock joints presents challenges for predictive modeling.This study presents an computed tomography and synthetic rock mass(CT-SRM)integrated analytical approach to investigate the mechanical properties of non-persistent jointed coal measures,with three notable findings contributions:Firstly,a novel digital reconstruction methodology for joint networks was developed using high-precision CT scanning and 3D reconstruction techniques,achieving accuracy of 96.03%.Secondly,the research has identified the critical joint diameter effect(30 mm)causing 30%-50%strength reduction and observed wing-shaped deformation induced by 30°secondary joints,elucidating a new size-controlled mechanism.Thirdly,quantitative correlation models between joint geometric parameters and macroscopic mechanical properties were established,offering insights for engineering stability assessment.The developed analytical framework offers a reliable solution for stability prediction of jointed rock masses in engineering applications.
基金supported by the Chinese National Key R&D Program(No.2022YFC3080200)the Chinese National Natural Science Foundation(No.42090054)。
文摘The rock masses in the hydro-fluctuation zone of reservoir banks sustain wettingdrying cycles(WDC),thereby affecting the stability of the reservoir bank slope.In this paper,rock masses with argillaceous siltstone and silty mudstone interbedded in Badong Formation were taken as the research object to investigate the variation of strength parameters of soft and hard interbedded rock masses with WDC and dip angle through laboratory experiments and numerical experiments.Some attempts were made to reveal the mechanical properties deterioration mechanism of interbedded rock masses by quantitatively analyzing the contribution of strength parameters deterioration of hard rocks,soft rocks,and bedding planes to the strength parameters deterioration of rock masses.The results indicate that the logarithmic function could be used to describe the deterioration of each strength parameter of both argillaceous siltstone and silty mudstone and bedding plane with the number of WDC.The strength parameters of interbedded rock masses decrease as the number of WDC increases,with the largest decrease after the first cycle and then slowing down in the later cycles.The strength parameters initially decrease and then increase as the dip angles increase.The impact of deteriorated strength parameters of bedding planes and rocks on the deterioration of strength parameters of interbedded rock masses differs significantly with the dip angle,which can be divided into four typical ranges of different controlling factors.
基金supported by Science and Technology Project of Yunnan Provincial Transportation Department(Grant No.25 of 2018)the National Natural Science Foundation of China(Grant No.52279107)The authors are grateful for the support by the China Scholarship Council(CSC No.202206260203 and No.201906690049).
文摘Face stability is an essential issue in tunnel design and construction.Layered rock masses are typical and ubiquitous;uncertainties in rock properties always exist.In view of this,a comprehensive method,which combines the Upper bound Limit analysis of Tunnel face stability,the Polynomial Chaos Kriging,the Monte-Carlo Simulation and Analysis of Covariance method(ULT-PCK-MA),is proposed to investigate the seismic stability of tunnel faces.A two-dimensional analytical model of ULT is developed to evaluate the virtual support force based on the upper bound limit analysis.An efficient probabilistic analysis method PCK-MA based on the adaptive Polynomial Chaos Kriging metamodel is then implemented to investigate the parameter uncertainty effects.Ten input parameters,including geological strength indices,uniaxial compressive strengths and constants for three rock formations,and the horizontal seismic coefficients,are treated as random variables.The effects of these parameter uncertainties on the failure probability and sensitivity indices are discussed.In addition,the effects of weak layer position,the middle layer thickness and quality,the tunnel diameter,the parameters correlation,and the seismic loadings are investigated,respectively.The results show that the layer distributions significantly influence the tunnel face probabilistic stability,particularly when the weak rock is present in the bottom layer.The efficiency of the proposed ULT-PCK-MA is validated,which is expected to facilitate the engineering design and construction.
文摘In this editorial we comment on the article by Huffaker et al,published in the current issue of the World Journal of Clinical Cases.Cardiac masses encompass a broad range of lesions,potentially involving any cardiac structure,and they can be either neoplastic or non-neoplastic.Primitive cardiac tumors are rare,while metastases and pseudotumors are relatively common.Cardiac masses frequently pose significant diagnostic and therapeutic challenges.Multimodality imaging is fundamental for differential diagnosis,treatment,and surgical planning.In particular cardiac magnetic resonance(CMR)is currently the gold standard for noninvasive tissue characterization.CMR allows evaluation of the relationship between the tumor and adjacent structures,detection of the degree of infiltration or expansion of the mass,and prediction of the possible malignancy of a mass with a high accuracy.Different flow charts of diagnostic work-up have been proposed,based on clinical,laboratory and imaging findings,with the aim of helping physicians approach the problem in a pragmatic way(“thinking inside the box”).However,the clinical complexity of cancer patients,in particular those with rare syndromes,requires a multidisciplinary approach and an open mind to go beyond flow charts and diagnostic algorithms,in other words the ability to“think outside the box”.
文摘Lesions of the left triangular ligament of the liver are rare,and there are even fewer cases of vascular tumors misdiagnosed as gastrointestinal stromal tumors.We comment on the two cases reported in the article.The article did not include pictures of laparoscopic surgery,making it unconvincing.For gastric submucosal lesions,enhanced computed tomography venous phase imaging may be beneficial for differential diagnosis.Although endoscopic ultrasound is an effective tool for diagnosing submucosal lesions of the stomach,due to various factors,it cannot achieve an accurate diagnosis.During endoscopic examination,a more accurate diagnosis can be made depending on the personal experience of the operators.
文摘The Standard Model of particle physics involves twelve fundamental fermions, treated as point particles, in four charge states. However, the Standard Model does not explain why only three fermions are in each charge state or account for neutrino mass. This holographic analysis treats charged Standard Model fermions as spheres with mass 0.187 g/cm<sup>2</sup> times their surface area, using the proportionality constant in the holographic relation between mass of the observable universe and event horizon radius. The analysis requires three Standard Model fermions per charge state and relates up quark and down quark masses to electron mass. Holographic analysis specifies electron mass, to six significant figures, in terms of fundamental constants α,ℏ,G,Λ and Ω Λ . Treating neutrinos as spheres and equating electron neutrino energy density with cosmic vacuum energy density predicts neutrino masses consistent with experiment.
基金funded by the National Natural Science Foundation of China(No.41972264)Zhejiang Provincial Natural Science Foundation of China(No.LR22E080002)the Key R&D Project of Zhejiang Province(No.2021C03159).
文摘Flexural toppling occurs when a series of layered rock masses bend towards their free face.It is important to evaluate the maximum bending degree and the requirement of supports of flexural toppling rock mass to prevent rock mass cracking and even failure leading to a landslide.Based on the rock tensile strain-softening model,this study proposes a method for calculating the maximum curvature(C_(ppmax))of flexural toppling rock masses.By applying this method to calculate Cppmax of 9 types of rock masses with different hardness and rock layer thickness,some conclusions are drawn:(1)the internal key factors affecting C_(ppmax)are E^(⋆)(E^(⋆)=E_(ss)/E_(0),where E_(0)and E_(ss)are the mean deformation moduli of the rock before and after reaching its peak tensile strength,respectively),the strainεt corresponding to the tensile strength of rock,and the thickness(h)of rock layers;(2)hard rock layers are more likely to develop into block toppling than soft rock layers;and(3)thin rock layers are more likely to remain in flexural toppling state than thick rock layers.In addition,it is found that C_(ppmax)for flexural toppling rock masses composed of bedded rocks such as gneiss is related to the tensile direction.
基金Project(2023YFC2907600)supported by the National Key Research and Development Program of ChinaProject(202203a07020011)supported by the Major Science and Technology Projects of Anhui Province,China+4 种基金Project(T2021137)supported by the National Talent Project,ChinaProject(T000508)supported by the Leading Talent Project of the Special Support Plan of Anhui Province,ChinaProject(GXXT-2021-075)supported by the University Synergy Innovation Program of Anhui Province,ChinaProject(2022AH010053)supported by the Excellent Scientific Research and Innovation Team of Universities in Anhui Province,ChinaProject(2022CX1004)supported by the Anhui University of Science and Technology Postgraduate Innovation Fund Project,China。
文摘Experiments on grouting-reinforced rock mass specimens with different particle sizes and features were carried out in this study to examine the effects of grouting reinforcement on the load-bearing characteristics of fractured rock mass.The strength and deformation features of grouting-reinforced rock mass were analyzed under different loading manners;the energy evolution mechanism of grouting-reinforced rock mass specimens with different particle sizes and features was investigated;the energy dissipation ratio and post-peak stress decreasing rate were employed to evaluate the bearing stability of grouting-reinforced rock mass.The results show that the strength and ductility of granite-reinforced rock mass(GRM)under biaxial loading are higher than that of sandstone-reinforced rock mass(SRM)under uniaxial loading.Besides,the energy evolution characteristics of grouting-reinforced rock mass under uniaxial and biaxial loading mainly could be divided into early,middle,and late stages.In the early stage,total,elastic,and dissipation energies were quite small with flatter curves;in the middle stage,elastic energy increased rapidly,whereas dissipation energy increased slowly;in the late stage,dissipation energy increased sharply.The energy dissipation ratio was used to represent the pre-peak plastic deformation.Under uniaxial loading,this ratio increased as the particle size increased and the pre-peak plastic deformation of grouting-reinforced rock mass became larger;under biaxial loading,it dropped as the particle size increased,and the pre-peak plastic deformation of grouting-reinforced rock mass became smaller.The post-peak stress decline rate A_(v) was used to assess the post-peak bearing performance of grouting-reinforced rock mass.Under uniaxial loading,parameter A_(v) exhibited reduction as the particle size kept increasing,and the ability of post-peak of grouting-reinforced rock mass to allow deformation development was greater,and the bearing capacity was greater;under biaxial loading,A_(v) increased with the particle size,and the ability of post-peak of grouting-reinforced rock mass to allow deformation development was low and the bearing capacity was reduced.The findings are considered instrumental in improving the stability of the roadway-surrounding rock by granite and sandstone grouting.
文摘The diagnostic approach to solid pancreatic masses has significantly evolved from the era when a focal pancreatic mass was almost synonymous to pancreatic ductal adenocarcinoma,to a wide spectrum of pancreatic lesions,some of which have good prognosis.With the advent of advanced diagnostic tools,particularly refined imaging and tissue acquisition techniques,a broader spectrum of differential diagnoses has been recognized,encompassing conditions ranging from neuroendocrine tumors or inflammatory masses,to rare entities like metastatic clear cell sarcoma or solitary fibrous tumors.We herein discuss case reports of some rare pancreatic lesions,which were diagnosed by combining clinical and imaging features and endoscopic ultrasound-guided tissue sampling and confirmed on surgical specimens.Further reports on these rare pancreatic tumors will contribute to a better understanding of their pathogenesis and effective management.
基金support from the National Natural Science Foundation of China(Grant Nos.52079134 and 51991393).
文摘The method for precursor information acquisition based on acoustic emission(AE)data for jointed rock masses is of significant importance for the early warning of dynamic disasters in underground engineering.A clustering-convolutional neural network(CNN)method is proposed,which comprises a clustering component and a CNN component.A series of uniaxial compression tests were conducted on granite specimens containing a persistent sawtooth joint,with different strain rates(105e102 s1)and joint inclination angles(0e50).The results demonstrate that traditional precursory indicators based on full waveforms are effective for obtaining precursor information of the intact rock failure.However,these indicators are not universally applicable to the failure of rock masses with a single joint.The clustering-CNN method has the potential to be applied to obtain precursor information for all three failure modes(Modes I,II and III).Following the waveform clustering analysis,the effective waveforms exhibit a low main frequency,as well as high energy,ringing count,and rise time.Furthermore,the clustering method and the precursory indicators influence the acquisition of final precursor information.The Birch hierarchical clustering method and the S value precursory indicator can help to obtain more accurate results.The findings of this study may contribute to the development of warning methods for underground engineering across faults.
基金supported by the Xi’an Key Laboratory of Geotechnical and Underground Engineering Open Fund Project (XKLGUEKF20-03)the Natural Science Basic Research Program of Shaanxi Province General Project-Youth Project(2024JC-YBQN-0258)。
文摘As one of the most common occurring geological landforms in deep rock formations, the dynamic mechanical properties of layered composite rock bodies under impact loading have been widely studied by scholars. To study the dynamic properties of soft and hard composite rocks with different thickness ratios, this paper utilizes cement, quartz sand and gypsum powder to construct soft and hard composite rock specimens and utilizes a combination of indoor tests, numerical calculations, and theoretical analyses to investigate the mechanical properties of soft and hard composite rock bodies. The test results reveal that:(1) When the proportion of hard rock increases from 20% to 50%, the strength of the combined rock body increases by 69.14 MPa and 87 MPa when the hard rock face and soft rock face are loaded, respectively;however, when the proportion of hard rock is the same, the compressive strength of the hard rock face impact is 9%-17% greater than that of the soft rock face impact;(2) When a specimen of soft and hard combined rock body is subjected to impact loading, the damage mode involves mixed tension and shear damage, and the cracks generally first appear at the ends of the specimen, then develop on the laminar surface from the impact surface, and finally end in the overall damage of the soft rock part. The development rate and the total number of cracks in the same specimen when the hard rock face is impacted are significantly greater than those when the soft rock face is impacted;(3) By introducing Weibull’s statistical strength theory to establish the damage variables of soft-hard combined rock bodies, combined with the DP strength criterion, the damage model and the Kelvin body are concatenated to obtain a statistical damage constitutive model, which can better fit the full stress-strain curve of soft-hard combined rock body specimens under a single impact load.
