期刊文献+
共找到220篇文章
< 1 2 11 >
每页显示 20 50 100
Urban Surroundings Influence on Air Temperature in a Small Urban Area of Curitiba-Brazil
1
作者 Cristiane Rossatto Candido Francine Aidie Rossi 《Computational Water, Energy, and Environmental Engineering》 2024年第2期95-111,共17页
The formation of urban climates constitutes a distinctive system intrinsically linked to the urban environment. This study aims to delve into the impact of the urban environment on climatic variables. The Urban Weathe... The formation of urban climates constitutes a distinctive system intrinsically linked to the urban environment. This study aims to delve into the impact of the urban environment on climatic variables. The Urban Weather Generator (UWG) algorithm was employed to generate climatic data, facilitating the creation of an epw climate file that corresponds to the urban characteristics surrounding the Centro Politécnico campus at the Federal University of Paraná (UFPR). Comprehensive analyses encompassing land use, occupancy patterns, albedo, surface absorption, anthropogenic heat, and architectural attributes were conducted. A comparative assessment between the UWG-derived air temperature values and meteorological station data revealed that the UWG effectively characterizes the air temperature patterns around the UFPR campus. The anticipated air temperature values consistently surpass the original dataset (SWERA), which was utilized as input, primarily during the hours from 3 p.m. to 7 a.m., showcasing the unmistakable urban heat island phenomenon. 展开更多
关键词 Urban Weather Generator Air Temperature Urban surroundings
下载PDF
Sedimentological Characterization of Alluvial Gold Deposits of Betrare-Oya and Its Surroundings (Cameroon Eastern Region) 被引量:1
2
作者 Daniel Mackaire Eloung Nna Paul Desiré Ndjigui +2 位作者 Joseph Quentin Yene Atangana Alexis Jacob Nyangono Abolo Constantin Maurice Ndongue 《International Journal of Geosciences》 2020年第12期783-799,共17页
Sedimentological methods such as granulometry, morphoscopy and heavy minerals analysis have been carried out to characterize alluvial gold deposits of Betare-Oya and its surroundings, with the aim to determine their o... Sedimentological methods such as granulometry, morphoscopy and heavy minerals analysis have been carried out to characterize alluvial gold deposits of Betare-Oya and its surroundings, with the aim to determine their origin and conditions in which they are formed and also to determine the mineralogical content of these deposits, their nature and distribution. It came out from this study the following: The alluvial deposits studied are sand, constituting of coarse fraction (grains), medium grains in abundant and fine grains. The average values of sorting index (S0) and coefficient of asymmetry (A) are respectively 2.53 and 0.73. These values indicate that the sand is poorly arranged and poorly sorted with a better classification or arrangement in the coarse fraction (grains). These are sediments that are deposited together by high competent currents. It would therefore probably be torrential deposits and or streams from short transport. Unused grains are dominating (80.5%) which translate a proximal source of the sediments. So it would be probably from the dismantling of the surrounding landforms. The heavy minerals studied revealed the presence of the following minerals;zircon, gold, sphene, green hornblende, tourmaline, rutile, augite, hypersthene, sillimanite, glau-cophane, biotite, staurotide, and the opaque. These minerals belong to the cortege of plutonic and metamorphic rocks from a single proximal distributing province. 展开更多
关键词 Betare-Oya and Its surroundings Alluvial Gold Deposits GRANULOMETRY Morphoscopy Heavy Minerals Polished Sections
下载PDF
Sub-Homogeneous Peridynamic Model for Fracture and Failure Analysis of Roadway Surrounding Rock
3
作者 Shijun Zhao Qing Zhang +3 位作者 Yusong Miao Weizhao Zhang Xinbo Zhao Wei Xu 《Computer Modeling in Engineering & Sciences》 SCIE EI 2024年第6期3167-3187,共21页
The surrounding rock of roadways exhibits intricate characteristics of discontinuity and heterogeneity.To address these complexities,this study employs non-local Peridynamics(PD)theory and reconstructs the kernel func... The surrounding rock of roadways exhibits intricate characteristics of discontinuity and heterogeneity.To address these complexities,this study employs non-local Peridynamics(PD)theory and reconstructs the kernel function to represent accurately the spatial decline of long-range force.Additionally,modifications to the traditional bondbased PD model are made.By considering the micro-structure of coal-rock materials within a uniform discrete model,heterogeneity characterized by bond random pre-breaking is introduced.This approach facilitates the proposal of a novel model capable of handling the random distribution characteristics of material heterogeneity,rendering the PD model suitable for analyzing the deformation and failure of heterogeneous layered coal-rock mass structures.The established numerical model and simulation method,termed the sub-homogeneous PD model,not only incorporates the support effect but also captures accurately the random heterogeneous micro-structure of roadway surrounding rock.The simulation results obtained using this model show good agreement with field measurements from the Fucun coal mine,effectively validating the model’s capability in accurately reproducing the deformation and failure mode of surrounding rock under bolt-supported(anchor cable).The proposed subhomogeneous PD model presents a valuable and effective simulation tool for studying the deformation and failure of roadway surrounding rock in coal mines,offering new insights and potential advancements. 展开更多
关键词 Roadway surrounding rock PERIDYNAMICS heterogeneous material fracture analysis numerical simulation
下载PDF
Numerical Simulation of Surrounding Rock Deformation and Grouting Reinforcement of Cross-Fault Tunnel under Different Excavation Methods
4
作者 Duan Zhu Zhende Zhu +2 位作者 Cong Zhang LunDai Baotian Wang 《Computer Modeling in Engineering & Sciences》 SCIE EI 2024年第3期2445-2470,共26页
Tunnel construction is susceptible to accidents such as loosening, deformation, collapse, and water inrush, especiallyunder complex geological conditions like dense fault areas. These accidents can cause instability a... Tunnel construction is susceptible to accidents such as loosening, deformation, collapse, and water inrush, especiallyunder complex geological conditions like dense fault areas. These accidents can cause instability and damageto the tunnel. As a result, it is essential to conduct research on tunnel construction and grouting reinforcementtechnology in fault fracture zones to address these issues and ensure the safety of tunnel excavation projects. Thisstudy utilized the Xianglushan cross-fault tunnel to conduct a comprehensive analysis on the construction, support,and reinforcement of a tunnel crossing a fault fracture zone using the three-dimensional finite element numericalmethod. The study yielded the following research conclusions: The excavation conditions of the cross-fault tunnelarray were analyzed to determine the optimal construction method for excavation while controlling deformationand stress in the surrounding rock. The middle partition method (CD method) was found to be the most suitable.Additionally, the effects of advanced reinforcement grouting on the cross-fault fracture zone tunnel were studied,and the optimal combination of grouting reinforcement range (140°) and grouting thickness (1m) was determined.The stress and deformation data obtained fromon-site monitoring of the surrounding rock was slightly lower thanthe numerical simulation results. However, the change trend of both sets of data was found to be consistent. Theseresearch findings provide technical analysis and data support for the construction and design of cross-fault tunnels. 展开更多
关键词 Cross-fault tunnel finite element analysis excavation methods surrounding rock deformation grouting reinforcement
下载PDF
Longitudinal vibration characteristics of a tapered pipe pile considering the vertical support of surrounding soil and construction disturbance
5
作者 Li Zhenya Pan Yunchao +2 位作者 He Xianbin Lv Chong Mohammad Towhid 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2024年第1期51-63,共13页
This research is concentrated on the longitudinal vibration of a tapered pipe pile considering the vertical support of the surrounding soil and construction disturbance.First,the pile-soil system is partitioned into f... This research is concentrated on the longitudinal vibration of a tapered pipe pile considering the vertical support of the surrounding soil and construction disturbance.First,the pile-soil system is partitioned into finite segments in the vertical direction and the Voigt model is applied to simulate the vertical support of the surrounding soil acting on the pile segment.The surrounding soil is divided into finite ring-shaped zones in the radial direction to consider the construction disturbance.Then,the shear complex stiffness at the pile-soil interface is derived by solving the dynamic equilibrium equation for the soil from the outermost to innermost zone.The displacement impedance at the top of an arbitrary pile segment is obtained by solving the dynamic equilibrium equation for the pile and is combined with the vertical support of the surrounding soil to derive the displacement impedance at the bottom of the upper adjacent segment.Further,the displacement impedance at the pile head is obtained based on the impedance function transfer technique.Finally,the reliability of the proposed solution is verified,followed by a sensitivity analysis concerning the coupling effect of the pile parameters,construction disturbance and the vertical support of the surrounding soil on the displacement impedance of the pile. 展开更多
关键词 tapered pipe pile longitudinal vibration vertical support of the surrounding soil construction disturbance displacement impedance
下载PDF
Development and application of novel high‐efficiency composite ultrafine cement grouts for roadway in fractured surrounding rocks
6
作者 Maolin Tian Shaojie Chen +1 位作者 Lijun Han Hongtian Xiao 《Deep Underground Science and Engineering》 2024年第1期53-69,共17页
The fractured surrounding rocks of roadways pose major challenges to safe mining.Grouting has often been used to reinforce the surrounding rocks to mitigate the safety risks associated with fractured rocks.The aim of ... The fractured surrounding rocks of roadways pose major challenges to safe mining.Grouting has often been used to reinforce the surrounding rocks to mitigate the safety risks associated with fractured rocks.The aim of this study is to develop highly efficient composite ultrafine cement(CUC)grouts to reinforce the roadway in fractured surrounding rocks.The materials used are ultrafine cement(UC),ultrafine fly ash(UF),ultrafine slag(US),and additives(superplasticizer[SUP],aluminate ultrafine expansion agent[AUA],gypsum,and retarder).The fluidity,bleeding,shrinkage,setting time,chemical composition,microstructure,degree of hydration,and mechanical property of grouting materials were evaluated in this study.Also,a suitable and effective CUC grout mixture was used to reinforce the roadway in the fractured surrounding rock.The results have shown that the addition of UF and US reduces the plastic viscosity of CUC,and the best fluidity can be obtained by adding 40%UF and 10%US.Since UC and UF particles are small,the pozzolanic effect of UF promotes the hydration reaction,which is conductive to the stability of CUC grouts.In addition,fine particles of UC,UF,and US can effectively fill the pores,while the volumetric expansion of AUA and gypsum decreases the pores and thus affects the microstructure of the solidified grout.The compressive test results have shown that the addition of specific amounts of UF and US can ameliorate the mechanical properties of CUC grouts.Finally,the CUC22‐8 grout was used to reinforce the No.20322 belt roadway.The results of numerical simulation and field monitoring have indicated that grouting can efficaciously reinforce the surrounding rock of the roadway.In this research,high‐performance CUC grouts were developed for surrounding rock reinforcement of underground engineering by utilizing UC and some additives. 展开更多
关键词 broken surrounding rock composite ultrafine cement(CUC)grouts grouting material grouting performance grouting reinforcement
下载PDF
Study on creep deformation and energy development of underground surrounding rock under four‐dimensional support
7
作者 Zhanguo Ma Junyu Sun +3 位作者 Peng Gong Pengfei Yan Nan Cui Ruichong Zhang 《Deep Underground Science and Engineering》 2024年第1期25-38,共14页
There is an urgent need to develop optimal solutions for deformation control of deep high‐stress roadways,one of the critical problems in underground engineering.The previously proposed four‐dimensional support(here... There is an urgent need to develop optimal solutions for deformation control of deep high‐stress roadways,one of the critical problems in underground engineering.The previously proposed four‐dimensional support(hereinafter 4D support),as a new support technology,can set the roadway surrounding rock under three‐dimensional pressure in the new balanced structure,and prevent instability of surrounding rock in underground engineering.However,the influence of roadway depth and creep deformation on the surrounding rock supported by 4D support is still unknown.This study investigated the influence of roadway depth and creep deformation time on the instability of surrounding rock by analyzing the energy development.The elastic strain energy was analyzed using the program redeveloped in FLAC3D.The numerical simulation results indicate that the combined support mode of 4D roof supports and conventional side supports is highly applicable to the stability control of surrounding rock with a roadway depth exceeding 520 m.With the increase of roadway depth,4D support can effectively restrain the area and depth of plastic deformation in the surrounding rock.Further,4D support limits the accumulation range and rate of elastic strain energy as the creep deformation time increases.4D support can effectively reduce the plastic deformation of roadway surrounding rock and maintain the stability for a long deformation period of 6 months.As confirmed by in situ monitoring results,4D support is more effective for the long‐term stability control of surrounding rock than conventional support. 展开更多
关键词 coal mines elastic strain energy four‐dimensional support large roadway depth long‐term stability control plastic deformation surrounding rock
下载PDF
Shield Excavation Analysis: Ground Settlement & Mechanical Responses in Complex Strata
8
作者 Baojun Qin Guangwei Zhang Wei Zhang 《Structural Durability & Health Monitoring》 EI 2024年第3期341-360,共20页
This study delves into the effects of shield tunneling in complex coastal strata, focusing on how this constructionmethod impacts surface settlement, the mechanical properties of adjacent rock, and the deformation of ... This study delves into the effects of shield tunneling in complex coastal strata, focusing on how this constructionmethod impacts surface settlement, the mechanical properties of adjacent rock, and the deformation of tunnelsegments. It investigates the impact of shield construction on surface settlement, mechanical characteristics ofnearby rock, and segment deformation in complex coastal strata susceptible to construction disturbances. Utilizingthe Fuzhou Binhai express line as a case study, we developed a comprehensive numerical model using theABAQUS finite element software. The model incorporates factors such as face force, grouting pressure, jack force,and cutterhead torque. Its accuracy is validated against field monitoring data from engineering projects. Simulationswere conducted to analyze ground settlement and mechanical changes in adjacent rock and segments acrossfive soil layers. The results indicate that disturbances are most significant near the excavation zone of the shieldmachine, with a prominent settlement trough forming and stabilizing around 2.0–3.0 D from the excavation. Theexcavation face compresses the soil, inducing lateral expansion. As grouting pressure decreases, the segmentexperiences upward buoyancy. In mixed strata, softer layers witness increased cutting, intensifying disturbancesbut reducing segment floatation. These findings offer valuable insights for predicting settlements, ensuring segmentand rock safety, and optimizing tunneling parameters. 展开更多
关键词 Shield construction complex strata finite element method mechanical properties of surrounding rock segment deformation settlement prediction
下载PDF
Forward prediction for tunnel geology and classification of surrounding rock based on seismic wave velocity layered tomography 被引量:1
9
作者 Bin Liu Jiansen Wang +2 位作者 Senlin Yang Xinji Xu Yuxiao Ren 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2023年第1期179-190,共12页
Excavation under complex geological conditions requires effective and accurate geological forward-prospecting to detect the unfavorable geological structure and estimate the classification of surround-ing rock in fron... Excavation under complex geological conditions requires effective and accurate geological forward-prospecting to detect the unfavorable geological structure and estimate the classification of surround-ing rock in front of the tunnel face.In this work,a forward-prediction method for tunnel geology and classification of surrounding rock is developed based on seismic wave velocity layered tomography.In particular,for the problem of strong multi-solution of wave velocity inversion caused by few ray paths in the narrow space of the tunnel,a layered inversion based on regularization is proposed.By reducing the inversion area of each iteration step and applying straight-line interface assumption,the convergence and accuracy of wave velocity inversion are effectively improved.Furthermore,a surrounding rock classification network based on autoencoder is constructed.The mapping relationship between wave velocity and classification of surrounding rock is established with density,Poisson’s ratio and elastic modulus as links.Two numerical examples with geological conditions similar to that in the field tunnel and a field case study in an urban subway tunnel verify the potential of the proposed method for practical application. 展开更多
关键词 Tunnel geological forward-prospecting Seismic wave velocity Layered inversion Surrounding rock classification Artificial neural network(ANN)
下载PDF
Relative importance of tidal flats and artificial habitats for two spoonbill species and related interspecific differences
10
作者 Takehiko Shimizu Masayuki Senzaki +1 位作者 Yuichiro Fujioka Satoquo Seino 《Avian Research》 SCIE CSCD 2023年第3期317-325,共9页
Artificial/seminatural environments,such as aquacultural ponds,saltpans,and croplands,have recently been acknowledged as important habitats for coastal waterbirds.Although coastal waterbirds tend to use artificial hab... Artificial/seminatural environments,such as aquacultural ponds,saltpans,and croplands,have recently been acknowledged as important habitats for coastal waterbirds.Although coastal waterbirds tend to use artificial habitats around tidal flats as roosting sites during high-tide,it remains unclear whether the importance of surrounding habitats relative to tidal flats varies among landscape types,seasons,species,or tidal conditions.The Black-faced Spoonbill(Platalea minor)and Eurasian Spoonbill(P.leucorodia)are two closely related sympatric species in East Asia with narrow and wide distribution ranges and habitat requirements,respectively.We therefore expect that both species will use surrounding artificial habitats across seasons at high tides,but Blackfaced Spoonbills will use them less frequently than Eurasian Spoonbills.Here,we address these hypotheses in the Imazu tidal flat and its surrounding environments in southern Japan.We investigated the habitat use and behavioral patterns of both species through route and behavioral surveys during the fall migration and wintering seasons in 2021.We found that both species used surrounding habitats including artificial ones more frequently than the tidal flat regardless of the tidal condition or season,but spoonbills used these habitats more frequently in winter than in autumn.We also found that Eurasian Spoonbills foraged in surrounding artificial habitats more frequently than Black-faced Spoonbills.These results not only demonstrate how coastal waterbirds exploit surrounding habitats relative to tidal flats but also suggest that the importance of surrounding habitats varies among species and seasons.Our study thus emphasizes that valuing and managing surrounding habitats in addition to tidal flats are key to conserving globally declining waterbirds. 展开更多
关键词 Artificial habitat BEHAVIOR Black-faced Spoonbill Eurasian Spoonbill Habitat use Surrounding environment Species distribution model Tidal flat
下载PDF
Failure mechanism and control countermeasures of surrounding rock at deep large section chamber intersection in the Wanfu Coal Mine
11
作者 SUN Xiao-ming QI Zhen-min +3 位作者 ZHANG Yong MIAO Cheng-yu ZHAO Cheng-wei HE Man-chao 《Journal of Mountain Science》 SCIE CSCD 2023年第7期2058-2075,共18页
In order to solve the problem of large deformation at the intersection of deep large section soft rock roadway,this paper takes the intersection of kilometer-deep roadway in the Wanfu Coal Mine as an engineering examp... In order to solve the problem of large deformation at the intersection of deep large section soft rock roadway,this paper takes the intersection of kilometer-deep roadway in the Wanfu Coal Mine as an engineering example and applies Negative Poisson’s Ratio(NPR)steel anchor cable in roadway support for the first time.By combining numerical simulation indoor test,theoretical analysis and field test,the deformation mechanism of surrounding rock at the intersection of deep-buried roadway was analyzed,and the control strategy with micro NPR steel anchor cable as the core was put forward.Through numerical simulation,the numerical analysis model of roadway intersection with different intersection angles and excavation sequence was constructed,and the impact of two key variables of rake angle and excavation sequence on the stability of surrounding rock at roadway intersection was studied.The optimal dip angle is 90°and the optimal excavation sequence was determined as pump house-pump house passage-substation.The mechanical properties of the micro-NPR steel anchor cable were studied through the static tensile test in the laboratory.The results showed that the micro-NPR steel anchor cable showed high constant resistance,uniform tensile,no yield platform,and no obvious necking phenomenon during breaking.Through theoretical derivation,it was calculated that the vertical stress of roadway intersection is 45 MPa,and the bearing capacity of superposed arch composed of micro NPR steel anchor cable is 1257 kN,which is enough to guarantee the overall stability of intersection.Support application test and monitoring were carried out on site,and it was verified that the combined support strategy of short and long micro NPR steel anchor cable has a good control effect on large deformation of surrounding rock at intersection,which provides a new support material and support means for the safety and stabilization control of surrounding rock at intersection. 展开更多
关键词 Mountain tunnel Composite lining Surrounding rock grade Force variation Primary support Secondary lining
下载PDF
Load laws of composite lining in mountain tunnel model tests and numerical simulation validation
12
作者 ZHOU Jian YANG Xin-an CHU Zheng 《Journal of Mountain Science》 SCIE CSCD 2023年第7期2041-2057,共17页
Currently,model tests are increasingly being used to simulate the construction of mountain tunnels,but the support structure of the model tests does not show the composite lining,and the force laws of the composite li... Currently,model tests are increasingly being used to simulate the construction of mountain tunnels,but the support structure of the model tests does not show the composite lining,and the force laws of the composite lining are not yet clear.In this research,the force variation of composite lining under three cases in model tests of deep-buried tunnels were carried out with the surrounding rock grade and installation time as the variation factors.The test results reveal that:(1)The suitable method to reduce the contact load between the secondary lining and primary support is to enhance the primary support in the soft and weak surrounding rock.Correspondingly,for ClassⅢsurrounding rock and better quality of surrounding rock,the primary support can lag behind the excavation face a certain distance.(2)The axial forces of the bolts tend to rise with concentration of 0.4 kN-0.7 kN after the secondary lining was installed.(3)With or without two to three excavation cycles delayed,the load sharing ratio of the secondary lining of the Class III surrounding rock is less than 10%.Finally,the numerical simulation verifies the feasibility of the model tests. 展开更多
关键词 Mountain tunnel Composite lining Surrounding rock grade Force variation Primary support Secondary lining
下载PDF
Frost heaving force considering synchronous damage to tunnel lining and surrounding rocks under freeze—thaw cycles
13
作者 LIU Wen-jun LING Tong-hua +1 位作者 HE Wen-chao LIU Xian-jun 《Journal of Mountain Science》 SCIE CSCD 2023年第4期1131-1146,共16页
In areas with seasonal freezing,when the tunnel lining concrete is saturated with water infiltrating the interior,the lining and the surrounding rocks will simultaneously freeze.However,the current calculation of the ... In areas with seasonal freezing,when the tunnel lining concrete is saturated with water infiltrating the interior,the lining and the surrounding rocks will simultaneously freeze.However,the current calculation of the frost heaving force fails to consider the synchronous damage to the lining and surrounding rocks under freeze-thaw cycles.Therefore,as per the elastic calculation model of the frost heaving force and model of steady-state heat transfer of circular tunnels,this study introduces the frost heaving rate of lining and surrounding rocks.First,the analytical solution of frost heaving force is obtained for simultaneous frost heaving of lining and surrounding rocks under any steady-state temperature field.Then,based on the fracture theory and meso-damage mechanics,the damage variables of lining and surrounding rocks under freeze-thaw cycles are extracted,representing their elastic modulus and porosity.Finally,the formula of frost heaving force for synchronous damage to the lining and surrounding rocks at any steady-state temperature field is obtained.The calculation results demonstrate that the lower the temperature inside the lining,the greater the frost heaving force.With the increasing number of freeze-thaw cycles,frost heaving force tends to gradually increase initially,reaching a peak value at 85 freeze-thaw cycles,decreasing to 80%of the peak value at 140 cycles before reaching a constant value.The lining participates in frost heaving,increasing the frost heaving force.The initial increase rate of frost heaving force is 15.7%.Changing the fitting coefficients s1 and s2 of the lining and surrounding rocks can effectively control the magnitude of the frost heaving force in the tunnels. 展开更多
关键词 Freeze-thaw cycles Frost heaving force Concrete lining Tunnel surrounding rock Synchronous damage
下载PDF
Dynamic Mechanical Behavior and Numerical Simulation of an Ancient Underground Rock Mass under Impact Loading
14
作者 Baoping Zou Zhiping Liu +2 位作者 Weifeng Jin Haonan Ding Zhanyou Luo 《Computer Modeling in Engineering & Sciences》 SCIE EI 2023年第1期517-539,共23页
To study the dynamic mechanical properties of tuff under different environmental conditions,the tuff from an ancient quarry in Shepan Island was prepared.The impact damage to the rock was tested using a triaxial dynam... To study the dynamic mechanical properties of tuff under different environmental conditions,the tuff from an ancient quarry in Shepan Island was prepared.The impact damage to the rock was tested using a triaxial dynamic impact mechanical testing system(TDIMTS)with different ground stresses,temperatures,and groundwater pressures.The time-strain relationship,dynamic stress-strain relationship,energy dissipation law,energy-peak strain relationship,and the impact damage pattern of the tuff specimens under impact air pressures were investigated.The TDIMTS experiment on ancient underground rock mass under impact loading was also simulated using the finite element analysis software LS-DYNA based on the Holmquist-Johnson-Cook(HJC)material model.The dynamic failure process,failure pattern and peak stress of tuff specimen were calculated.The simulation results obtained using the above methods were in good agreement with the experimental results.The results of the dynamic experiment show that with the same local stress,groundwater pressure,and temperature,the damage to the tuff specimens caused by blasting and quarrying disturbances gradually increases as the impact pressure increases.Under the same local stress,groundwater pressure,and temperature,the energy required to rupture the tuffs in ancient underground caverns is relatively small if the impact pressure is low accordingly,but as the impact pressure increases,the damage to the tuff caused by quarrying disturbance gradually increases.The damage gradually increases and the degree of damage to the tuff and the strain energy exhibit asymptotic growth when the tuff specimens are subjected to the greater strain energy,increasing the degree of rupturing of the tuff.In addition,the average crushing size decreases with increasing strain energy.By comparing the simulation results with the experimental results,it was found that the HJC model reflected the dynamic impact performance of tuff specimen,and the simulation results showed an evident strain rate effect.These results of this study can offer some guidance and theoretical support for the stability evaluation,protection,and safe operation of the ancient underground caverns in future. 展开更多
关键词 Ancient underground caverns numerical simulation thermal-hydraulic-mechanical coupling dynamic impact TUFF stability of surrounding rock
下载PDF
Research on Active Safety Methodologies for Intelligent Railway Systems
15
作者 Yong Qin Zhiwei Cao +6 位作者 Yongfu Sun Linlin Kou Xuejun Zhao Yunpeng Wu Qinghong Liu Mingming Wang Limin Jia 《Engineering》 SCIE EI CAS CSCD 2023年第8期266-279,共14页
Safety is essential when building a strong transportation system.As a key development direction in the global railway system,the intelligent railway has safety at its core,making safety a top priority while pursuing t... Safety is essential when building a strong transportation system.As a key development direction in the global railway system,the intelligent railway has safety at its core,making safety a top priority while pursuing the goals of efficiency,convenience,economy,and environmental friendliness.This paper describes the state of the art and proposes a system architecture for intelligent railway systems.It also focuses on the development of railway safety technology at home and abroad,and proposes the active safety method and technology system based on advanced theoretical methods such as the in-depth integration of cyber–physical systems(CPS),data-driven models,and intelligent computing.Finally,several typical applications are demonstrated to verify the advancement and feasibility of active safety technology in intelligent railway systems. 展开更多
关键词 Intelligent railway system Active safety methodology Prognostics and health management Intelligent surrounding perception Operation and maintenance risk control
下载PDF
Heterogeneity identification method for surrounding rock of large-section rock tunnel faces based on support vector machine
16
作者 Wenhao Yi Mingnian Wang +4 位作者 Jianjun Tong Siguang Zhao Jiawang Li Dengbin Gui Xiao Zhang 《Railway Sciences》 2023年第1期48-67,共20页
Purpose–The purpose of the study is to quickly identify significant heterogeneity of surrounding rock of tunnel face that generally occurs during the construction of large-section rock tunnels of high-speed railways.... Purpose–The purpose of the study is to quickly identify significant heterogeneity of surrounding rock of tunnel face that generally occurs during the construction of large-section rock tunnels of high-speed railways.Design/methodology/approach–Relying on the support vector machine(SVM)-based classification model,the nominal classification of blastholes and nominal zoning and classification terms were used to demonstrate the heterogeneity identification method for the surrounding rock of tunnel face,and the identification calculation was carried out for the five test tunnels.Then,the suggestions for local optimization of the support structures of large-section rock tunnels were put forward.Findings–The results show that compared with the two classification models based on neural networks,the SVM-based classification model has a higher classification accuracy when the sample size is small,and the average accuracy can reach 87.9%.After the samples are replaced,the SVM-based classification model can still reach the same accuracy,whose generalization ability is stronger.Originality/value–By applying the identification method described in this paper,the significant heterogeneity characteristics of the surrounding rock in the process of two times of blasting were identified,and the identification results are basically consistent with the actual situation of the tunnel face at the end of blasting,and can provide a basis for local optimization of support parameters. 展开更多
关键词 Rock tunnel Surrounding rock HETEROGENEITY Support vector machine High-speed railway
下载PDF
Research on the “Equivalent Effect” of Subtitling Translation in Garfield Ⅱ
17
作者 肖聪 《海外英语》 2013年第16期137-138,160,共3页
As a large number of foreign films have flooded into the Chinese film market, subtitling translation plays an important role in helping the audience understand and learn about some information and cultures from differ... As a large number of foreign films have flooded into the Chinese film market, subtitling translation plays an important role in helping the audience understand and learn about some information and cultures from different countries. This paper mainly uses Peter Newmark's"equivalent effect"as a theoretical foundation to analyze the features of two kitties'(Garfield and Prince) source language (English) and target language (Chinese) in the film Garfield Ⅱ based on their living surroundings and social status. 展开更多
关键词 LIVING surroundings SOCIAL Status SUBTITLING TRANS
下载PDF
关于地下洞室围岩稳定性问题的思考 被引量:3
18
作者 翁义孟 杨健 《水力发电》 北大核心 2010年第11期20-22,共3页
围岩卸荷区原处于三维应力状态,洞室开挖,导致围岩卸荷、岩面围压降低和应力重分布,使围岩产生变形乃至失稳。围岩变形同地应力以及围岩自身的力学性能有关,还受到岩体结构面、应力集中以及洞室布置等方面的影响。岩体变形的本构关系、... 围岩卸荷区原处于三维应力状态,洞室开挖,导致围岩卸荷、岩面围压降低和应力重分布,使围岩产生变形乃至失稳。围岩变形同地应力以及围岩自身的力学性能有关,还受到岩体结构面、应力集中以及洞室布置等方面的影响。岩体变形的本构关系、支护与围岩的互动机制相当复杂,要从原型测试、仿真分析、动态设计等方面进行深入探索。 展开更多
关键词 地下洞室围岩 稳定性问题 SURROUNDING Rock 三维应力状态 岩体变形 应力重分布 岩体结构面 原型测试 应力集中 卸荷区 围岩变形 力学性能 互动机制 仿真分析 洞室开挖 洞室布置 动态设计 本构关系 地应力 支护
下载PDF
《德伯家的苔丝》中苔丝悲剧的浅析(英文) 被引量:1
19
作者 谢海燕 《海外英语》 2012年第8X期199-200,共2页
Tess of the D'Urbervilles is one of Thomas Hardy's most famous novels.In this novel,the heroine,Tess,is figured with intelligence as well as beauty.She possesses all of praise-worthy qualities of labors:pure,i... Tess of the D'Urbervilles is one of Thomas Hardy's most famous novels.In this novel,the heroine,Tess,is figured with intelligence as well as beauty.She possesses all of praise-worthy qualities of labors:pure,industrious,responsible,brave and fortitudinous.And Tess has long been regarded as the most exceptional woman character in literary history.However,the life of this pure woman is tragic.This paper mainly analyzes the external reasons and internal reasons that results in the tragedy which she is changing from a girl with beauty and pureness to a young lady with muddling along and giving herself up,at last she walks to the execution ground.From all the points mentioned above,we can better and deeply understand Tess and her tragedy,and we can know the root of the Tess's tragedy is the evil capitalist society at that time. 展开更多
关键词 TRAGEDY CAPITALIST SOCIETY EXTERNAL surroundings i
下载PDF
A comparison of tectonic ambient shear stress value in China with that in western USA
20
作者 陈培善 白彤霞 李保昆 《Acta Seismologica Sinica(English Edition)》 CSCD 2002年第5期503-509,共7页
A method is proposed to estimate average tectonic ambient shear stress value for a region. Thus the average stress values of 19 regions in western USA, and 43 regions (each region is 1010) in Chinese mainland and its ... A method is proposed to estimate average tectonic ambient shear stress value for a region. Thus the average stress values of 19 regions in western USA, and 43 regions (each region is 1010) in Chinese mainland and its surroundings have been obtained. The data of 15 993 earthquakes are from the Internet Centroid Moment Tensor solution made by Harvard University from 1997 to 1999. The results demonstrate that there are highest average stress values in the regions of south California of USA and its off coast sea, reach to 12.0 MPa and 13.7 MPa respectively, then gradually decrease toward north, south, and east. The lowest value is 8.7 MPa and 63% of highest value. The average stress values in northern Xinjiang and in the Chayu region of Tibet are 17.2 and 12.9 MPa respectively. They are highest values in China and higher than USAs. The average stress value in North China, Yunnan, Sichuan, Taiwan is similar to south California of USA. The average stress value in South-North seismic zone is about 13 MPa, a little higher than south California. The distribution of average stress value for two important regions provides basic data for geology. These results are useful to research earthquake activity background and attenuation relation of strong ground motion parameters (e.g. peak acceleration and response spectra). 展开更多
关键词 AVERAGE TECTONIC ambient shear STRESS VALUE COMPARISON of AVERAGE STRESS VALUE Chinese MAINLAND and its surroundings western USA
下载PDF
上一页 1 2 11 下一页 到第
使用帮助 返回顶部