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Effect of environment change on the strength of cement/lime treated clays

Takenori HINO, Rui JIA, Seiji SUEYOSHI, Tri HARIANTO

《结构与土木工程前沿(英文)》 2012年 第6卷 第2期   页码 153-165 doi: 10.1007/s11709-012-0153-y

摘要: The field strengths of cement/lime treated clays were investigated in the Ariake Sea costal lowlands. The deposition environment of the investigation location is reconstructed and compared to the present ground environment. The mechanism of the ground environment change and its effect on the strength of cement/lime treated soil are discussed. The strength development of improved soil using cement and lime in different curing environments was investigated in the laboratory for studying the effect of environment change on the strength also. It has been found that the strength deterioration of improved soil in deep mixing method is due to 1) the ground environment change due to the secondary oxidation which results in low pH value and high organic content, and 2) the formations of the porous structures result from the elution of the calcium ions. Also, it has been found that the initial strength increase of the improved soil is related to the dissolved silica and that the dissolution of the silica in clay minerals needs long time. When examining the long-term strength for preventing strength degradation, the effect of environmental change has to be considered. The importance of measuring pH and oxidation-reduction potential (ORP) of the ground for cement/lime solidification method is explained.

关键词: soil solidification     ground environment     strength deterioration     pH     oxidation-reduction potential (ORP)     silica    

Mechanical responses of multi-layered ground due to shallow tunneling with arbitrary ground surface load

《结构与土木工程前沿(英文)》 2023年 第17卷 第5期   页码 745-762 doi: 10.1007/s11709-023-0935-4

摘要: An analytical model based on complex variable theory is proposed to investigate ground responses due to shallow tunneling in multi-layered ground with an arbitrary ground surface load. The ground layers are assumed to be linear-elastic with full-stick contact between them. To solve the proposed multi-boundary problem, a series of analytic functions is introduced to accurately express the stresses and displacements contributed by different boundaries. Based on the principle of linear-elastic superposition, the multi-boundary problem is converted into a superposition of multiple single-boundary problems. The conformal mappings of different boundaries are independent of each other, which allows the stress and displacement fields to be obtained by the sum of components from each boundary. The analytical results are validated based on numerical and in situ monitoring results. The present model is superior to the classical model for analyzing ground responses of shallow tunneling in multi-layered ground; thus, it can be used with assurance to estimate the ground movement and surface building safety of shallow tunnel constructions beneath surface buildings. Moreover, the solution for the ground stress distribution can be used to estimate the safety of a single-layer composite ground.

关键词: analytical model     mechanical response     multi-layered ground     shallow tunneling     ground surface load     complex variable solution    

R&D of the ground-coupled heat pump technology in China

Nairen DIAO, Ping CUI, Junhong LIU, Zhaohong FANG,

《能源前沿(英文)》 2010年 第4卷 第1期   页码 47-54 doi: 10.1007/s11708-009-0080-3

摘要: The ground-coupled heat pump (GCHP) systems have been identified as one of the best sustainable energy technologies for space heating and cooling in residential and commercial buildings. In this paper, research on and development of the GCHP technology in China are summarized. New models are presented for efficient thermal analysis of ground heat exchangers, of which one- and two-dimensional solid cylindrical source models and their analytical solutions are devised to deal with pile ground heat exchangers. Analytical solutions are also derived for vertical and inclined finite line source models as well as for a groundwater advection model. Explicit solutions of a quasi-three-dimensional model can be used to better evaluate the thermal resistance inside boreholes. Studies on hybrid GCHP systems and the thermal response test in China are also commented.

关键词: ground source heat pump     ground heat exchanger     HVAC     China    

INTERACTIONS BETWEEN ABOVE AND BELOW GROUND PLANT STRUCTURES: MECHANISMS AND ECOSYSTEM SERVICES

《农业科学与工程前沿(英文)》 2022年 第9卷 第2期   页码 197-213 doi: 10.15302/J-FASE-2021433

摘要:

Interactions between above and below ground parts of plants can be considered under the (overlapping) categories of energy, material and information. Solar energy powers photosynthesis and transpiration by above ground structures, and drives most water uptake through roots and supplies energy as organic matter to below ground parts, including diazotrophic symbionts and mycorrhizas. Material transfer occurs as water and dissolved soil-derived elements transport up the xylem, and a small fraction of water moving up the xylem with dissolved organic carbon and other solutes down the phloem. The cytosolic nature of sieve tubes accounts for at least some of the cycling of K, Mg and P down the phloem. NO3 assimilation of above ground parts requires organic N transport down phloem with, in some cases, organic anions related to shoot acid-base regulation. Long-distance information transfer is related development, biotic and abiotic damage, and above and below ground resource excess and limitation. Information transfer can involve hydraulic, electrical and chemical signaling, with their varying speeds of transmission and information content. Interaction of above and below ground plant parts is an important component of the ecosystem service of storing atmospheric CO2 as organic C in soil, a process that has decreased since the origin of agriculture.

关键词: aerenchyma / carbon accumulation / hormones / phloem / xylem    

Shanghai center project excavation induced ground surface movements and deformations

Guolin XU, Jiwen ZHANG, Huang LIU, Changqin REN

《结构与土木工程前沿(英文)》 2018年 第12卷 第1期   页码 26-43 doi: 10.1007/s11709-017-0439-1

摘要: Empirical data on deep urban excavations can provide designers a significant reference basis for assessing potential deformations of the deep excavations and their impact on adjacent structures. The construction of the Shanghai Center involved excavations in excess of 33-m-deep using the top-down method at a site underlain by thick deposits of marine soft clay. A retaining system was achieved by 50-m-deep diaphragm walls with six levels of struts. During construction, a comprehensive instrumentation program lasting 14 months was conducted to monitor the behaviors of this deep circular excavation. The following main items related to ground surface movements and deformations were collected: (1) walls and circumferential soils lateral movements; (2) peripheral soil deflection in layers and ground settlements; and (3) pit basal heave. The results from the field instrumentation showed that deflections of the site were strictly controlled and had no large movements that might lead to damage to the stability of the foundation pit. The field performance of another 21cylindrical excavations in top-down method were collected to compare with this case through statistical analysis. In addition, numerical analyses were conducted to compare with the observed data. The extensively monitored data are characterized and analyzed in this paper.

关键词: deep excavation     foundation pit     soft clay     top-down method     field observation     ground surface movements     ground deformations    

Seismic ground motion analysis of Shanghai Pudong Airport site considering the effects of spatial correlation

JIANG Tong, CHEN Laiyun, XING Hailing, L? Xilin

《结构与土木工程前沿(英文)》 2007年 第1卷 第4期   页码 430-435 doi: 10.1007/s11709-007-0058-3

摘要: The terminal No. II of Shanghai Pudong International Airport is located at Pudong District of Shanghai City near shore of East China Sea, and the area of the long-span terminal is 400 m × 200 m. The construction site of the terminal locates on the irregular topography, and its alluvium achieves about 300 m in thickness. The spatial correlation of seismic ground motion, as well as the amplification of soft alluvium and the effect of irregular topography, should be considered. This paper uses a simplified method to obtain the response spectrum of the engineering bedrock under the irregular topography. The spectrum is used to generate the sets of spatially correlative horizontal and vertical seismic motions. The surface ground motion was calculated under incidence of the spatially correlative seismic motion by 2D finite element method (FEM) model considering nonlinear properties of the soil by means of the equivalent linear method. In order to compare the effect of 2D irregular topography, the seismic response analysis of 1D model is carried out by using the equivalent linear method. For indicating the effect of the spatial correlation of input motions, the horizontal uniform inputs, as well as the horizontal and vertical uniform input are carried out for the seismic response analysis of the site. Finally, some characteristics of seismic ground motion calculated for previously mentioned cases are compared.

关键词: surface ground     horizontal uniform     Finally     seismic ground     correlative seismic    

Evaluation of the performance of a centralized ground-water heat pump system in cold climate region

Shilei LU,Zhe CAI,Li ZHANG,Yiran LI

《能源前沿(英文)》 2014年 第8卷 第3期   页码 394-402 doi: 10.1007/s11708-014-0310-1

摘要: The aim of this study is to evaluate the performance of a centralized open-loop ground-water heat pump (GWHP) system for climate conditioning in Beijing with a cold climate in China. Thus, a long-time test was conducted on a running GWHP system for the heating season from December 2011 to March 2012. The analysis of the testing data indicates that the average heat-pump coefficient of performance (COP) and the COP of the system (COPs) are 4.27 and 2.59. The low value and large fluctuation in the range of COP are found to be caused by the heat transfixion in the aquifer and the bypass in the circulation loop. Therefore, some suggestions are proposed to improve the performance for GWHPs in the cold climate region in China.

关键词: ground-water heat pump (GWHP)     actual coefficient of performance     heat transfixion    

Optimisation for interconnected energy hub system with combined ground source heat pump and borehole

Da HUO, Wei WEI, Simon Le BLOND

《能源前沿(英文)》 2018年 第12卷 第4期   页码 529-539 doi: 10.1007/s11708-018-0580-0

摘要: Ground source heat pumps (GSHP) give zero-carbon emission heating at a residential level. However, as the heat is discharged, the temperature of the ground drops, leading to a poorer efficiency. Borehole inter-seasonal thermal storage coupled with GSHP maintains the efficiency at a high level. To adequately utilize the high performance of combined GSHP and the borehole system to further increase system efficiency and reduce cost, such a combined heating system is incorporated into the interconnected multi-carrier system to support the heat load of a community. The borehole finite element (FE) model and an equivalent borehole transfer function are proposed and respectively applied to the optimisation to analyze the variation of GSHP performance over the entire optimisation time horizon of 24 h. The results validate the borehole transfer function, and the optimisation computation time is reduced by 17 times compared with the optimisation using the FE model.

关键词: borehole thermal storage     energy hub     ground source heat pumps (GSHP)     particle swarm optimisation    

Numerical study on the seismic response of the underground subway station- surrounding soil mass-ground

Guobo WANG, Mingzhi YUAN, Xianfeng MA, Jun WU

《结构与土木工程前沿(英文)》 2017年 第11卷 第4期   页码 424-435 doi: 10.1007/s11709-016-0381-7

摘要: Ground buildings constructed above metro station have increased very quickly due to the limited land resources in urban areas. In this paper, the seismic response of the Underground subway station-Surrounding soil mass-Ground adjacent buildings (USG) system subjected to various seismic loading is studied through numerical analysis. The numerical model is established in terms of the calculation domain, boundary condition, and contact property between soil and structure based on the real project. The reciprocal influence between subway station and ground adjacent building, and their effects on the dynamic characteristics of surrounding soil mass are also investigated. Through the numerical study, it is found that the impact of underground structure on the dynamic characteristics of the surrounding soil mass depends on its own dimension, and the presence of underground structure has certain impact on the seismic response of ground adjacent building. Due to the presence of underground structure and ground adjacent building, the vertical acceleration generated by the USG system cannot be ignored. The outcomes of this study can provide the references for seismic design of structures in the USG system.

关键词: underground subway station     ground adjacent building     seismic response    

GENOME EDITING: A GROUND BREAKING RESEARCH HAS BEEN RANKED TOP 10 ENGINEERING FRONTS FROM 2017 TO 2021

《农业科学与工程前沿(英文)》 2022年 第9卷 第2期   页码 309-311 doi: 10.15302/J-FASE-2022440

基于多传感器融合的智能车在野外环境中的障碍物检测研究 Review

胡劲文,郑博尹,王策,赵春晖,侯晓磊,潘泉,徐钊

《信息与电子工程前沿(英文)》 2020年 第21卷 第5期   页码 649-808 doi: 10.1631/FITEE.1900518

摘要: 随着传感器融合技术发展,人们对智能地面车辆进行大量研究,其中障碍物检测是一个关键技术。障碍物检测是一项复杂任务,涉及多种障碍物、传感器特性和环境条件。虽然道路驾驶员辅助系统或自动驾驶系统已得到充分研究,但是为城市场景结构化道路开发的方法应用于野外环境时,可能因不确定性和多样性而失效。单一类型传感器由于感受范围、信号特征和检测环境的限制,难以满足障碍物检测需求,这促使研究人员和工程师开发多传感器融合方法和系统集成。该综述旨在总结野外环境中智能地面车辆的车载多传感器配置的主要考虑事项,为用户提供根据性能要求和应用环境选择传感器的指南。本文回顾了最新多传感器融合方法和系统原型,将其与对应的异构传感器配置相关联,讨论了新兴技术和面临的挑战。

关键词: 多传感器融合;障碍物检测;野外环境;智能车;无人驾驶地面车辆    

Application of MoS in the space environment: a review

《机械工程前沿(英文)》 2023年 第18卷 第3期 doi: 10.1007/s11465-023-0755-1

摘要: A considerable portion of space mechanism failures are related to space tribological problems. Cold welding in high vacuum; surface erosion and collision damage caused by various radiations, high temperature oxidation under atomic oxygen (AO) bombardment; and thermal stress caused by temperature alternation all alter the physical, chemical, and friction properties of materials. In particular, the space vibration caused by alternating temperatures and microgravity environments can alter the motion of the contact body, further affecting its friction properties. Improving the friction properties of contact surfaces in the space environment is an important way to extend the service life of spacecraft. Traditional lubricants can no longer meet the lubrication requirements of the space environment. This study describes the characteristics of the space environment and the applications of solid lubricants. The friction properties of MoS2, a solid lubricant widely used in space, are discussed. The synergistic lubrication of MoS2 with surface textures or metals is presented. Advances in research on the friction properties of collision sliding contacts in the space environment are reviewed. The combination of MoS2 and soft metals with surface textures is introduced to reduce the effects of vibration environments on the friction properties of moving parts in space mechanisms. Finally, the challenges and future research interests of MoS2 films in space tribology are presented.

关键词: MoS2     soft metal     space environment     surface texture     synergistic effect     vibration    

Linking elements to outcomes of knowledge transfer in the project environment: Current review and future

《工程管理前沿(英文)》 2022年 第9卷 第2期   页码 221-238 doi: 10.1007/s42524-022-0195-3

摘要: A project is a specific effort to create a unique product, so it is a favorable place for knowledge creation and development. Knowledge can be transferred inside and outside projects and their parent project-based organizations, thus affecting project performance and organizational competitiveness. However, the current research on the elements and outcomes of knowledge transfer (KT) in the project environment lacks completeness and clarity, and that on the different levels of KT is fragmented. This study aims to conduct comprehensive research to determine and link the elements and outcomes of KT in the project environment. The authors systematically analyzed the relevant literature from 2000 to 2021, which showed an increasing publication trend. They divided KT in the project environment into three levels according to the transfer scenario: Intra-project, cross-project, and cross-organizational KT. Five-dimensional transfer elements and two-dimensional transfer outcomes were then identified and analyzed from previous literature. Lastly, the relationships between the transfer elements and outcomes were gathered to create a comprehensive model. Importantly, the knowledge gap in the current literature was highlighted, and future research directions were put forward. This study builds a theoretical framework linking transfer elements to outcomes that can serve as a basis for scholars and practitioners to develop effective strategies for KT in the project environment.

关键词: knowledge transfer     knowledge management     project management     project environment     literature review    

Lateral displacement of soft ground under vacuum pressure and surcharge load

Chin-Yee ONG, Jin-Chun CHAI

《结构与土木工程前沿(英文)》 2011年 第5卷 第2期   页码 239-248 doi: 10.1007/s11709-011-0110-1

摘要: Surcharge load (e.g. embankment fill) will induce settlement and outward lateral displacement, while vacuum pressure will induce settlement and inward lateral displacement of a ground. Ideally, combination of surcharge load and vacuum pressure can reduce or minimize the lateral displacement. Laboratory large scale model (length: 1.50 m, width: ~0.62 m, height: 0.85 m) tests and finite element analyses (FEA) were conducted to investigate the main influencing factors on lateral displacement of a soft clayey ground under the combination of vacuum pressure and surcharge load. For the conditions investigated, the results indicate that the outward lateral displacement increases with the increase of the ratio of surcharge load to vacuum pressure ( ) and the loading rate of the surcharge load ( ). Also, it is shown that for a given and condition, lateral displacement reduces with the increase of the initial undrained shear strength ( ) of the ground. To predict the lateral displacement of a ground under the combination of surcharge load and vacuum pressure, the loading conditions in terms of and , and value of the ground have to be considered.

关键词: vacuum consolidation     lateral displacement     PVD     finite element analysis     surcharge load    

Digital twin for healthy indoor environment: A vision for the post-pandemic era

《工程管理前沿(英文)》 2023年 第10卷 第2期   页码 300-318 doi: 10.1007/s42524-022-0244-y

摘要: Indoor environment has significant impacts on human health as people spend 90% of their time indoors. The COVID-19 pandemic and the increased public health awareness have further elevated the urgency for cultivating and maintaining a healthy indoor environment. The advancement in emerging digital twin technologies including building information modeling (BIM), Internet of Things (IoT), data analytics, and smart control have led to new opportunities for building design and operation. Despite the numerous studies on developing methods for creating digital twins and enabling new functionalities and services in smart building management, very few have focused on the health of indoor environment. There is a critical need for understanding and envisaging how digital twin paradigms can be geared towards healthy indoor environment. Therefore, this study reviews the techniques for developing digital twins and discusses how the techniques can be customized to contribute to public health. Specifically, the current applications of BIM, IoT sensing, data analytics, and smart building control technologies for building digital twins are reviewed, and the knowledge gaps and limitations are discussed to guide future research for improving environmental and occupant health. Moreover, this paper elaborates a vision for future research on integrated digital twins for a healthy indoor environment with special considerations of the above four emerging techniques and issues. This review contributes to the body of knowledge by advocating for the consideration of health in digital twin modeling and smart building services and presenting the research roadmap for digital twin-enabled healthy indoor environment.

关键词: digital twin     healthy indoor environment     building information modeling     occupant–building interaction     COVID-19    

标题 作者 时间 类型 操作

Effect of environment change on the strength of cement/lime treated clays

Takenori HINO, Rui JIA, Seiji SUEYOSHI, Tri HARIANTO

期刊论文

Mechanical responses of multi-layered ground due to shallow tunneling with arbitrary ground surface load

期刊论文

R&D of the ground-coupled heat pump technology in China

Nairen DIAO, Ping CUI, Junhong LIU, Zhaohong FANG,

期刊论文

INTERACTIONS BETWEEN ABOVE AND BELOW GROUND PLANT STRUCTURES: MECHANISMS AND ECOSYSTEM SERVICES

期刊论文

Shanghai center project excavation induced ground surface movements and deformations

Guolin XU, Jiwen ZHANG, Huang LIU, Changqin REN

期刊论文

Seismic ground motion analysis of Shanghai Pudong Airport site considering the effects of spatial correlation

JIANG Tong, CHEN Laiyun, XING Hailing, L? Xilin

期刊论文

Evaluation of the performance of a centralized ground-water heat pump system in cold climate region

Shilei LU,Zhe CAI,Li ZHANG,Yiran LI

期刊论文

Optimisation for interconnected energy hub system with combined ground source heat pump and borehole

Da HUO, Wei WEI, Simon Le BLOND

期刊论文

Numerical study on the seismic response of the underground subway station- surrounding soil mass-ground

Guobo WANG, Mingzhi YUAN, Xianfeng MA, Jun WU

期刊论文

GENOME EDITING: A GROUND BREAKING RESEARCH HAS BEEN RANKED TOP 10 ENGINEERING FRONTS FROM 2017 TO 2021

期刊论文

基于多传感器融合的智能车在野外环境中的障碍物检测研究

胡劲文,郑博尹,王策,赵春晖,侯晓磊,潘泉,徐钊

期刊论文

Application of MoS in the space environment: a review

期刊论文

Linking elements to outcomes of knowledge transfer in the project environment: Current review and future

期刊论文

Lateral displacement of soft ground under vacuum pressure and surcharge load

Chin-Yee ONG, Jin-Chun CHAI

期刊论文

Digital twin for healthy indoor environment: A vision for the post-pandemic era

期刊论文