检索结果-南通市图书馆

Thermal Characteristics of the Embankment with Crushed Rock Side Slope to Mitigate Thaw Settlement Hazards of the Qinghai-Tibet Railway

引用

Acta Geologica Sinica(English Edition) 2009年第5期83卷 1000-1007页

作者： li guoyu MU Yanhu ZHANG Xia State Key Laboratory of Frozen Soil Engineering CAREERL Chinese Academy of Science Lanzhou 730000 China School of Energy and Power Engineering Lanzhou University of Technology Lanzhou 730050 China

Permafrost （perennially frozen ground） appears widely in the Golmud-Lhasa section of the Qinghai-Tibet railway and is characterized by high ground temperature （≥1℃） and massive ground ice. Under the scenarios of global warming and human activity, the permafrost under the railway will gradually thaw and the massive ground ice will slowly melt, resulting in some thaw settlement hazards, which mainly include longitudinal and lateral cracks, and slope failure. The crushed rock layer has a thermal semiconductor effect under the periodic fluctuation of natural air. It can be used to lower the temperature of the underlying permafrost along the Qinghai-Tibet railway, and mitigate the thaw settlement hazards of the subgrade. In the present paper, the daily and annual changes in the thermal characteristics of the embankment with crushed rock side slope （ECRSS） were quantitatively simulated using the numerical method to study the cooling effect of the crushed rock layer and its mitigative ability. The results showed that the ECRSS absorbed some heat in the daytime in summer, but part of it was released at night, which accounted for approximately 20% of that absorbed. Within a year, it removed more heat from the railway subgrade in winter than that absorbed in summer. It can store approximately 20% of the ＂cold＂ energy in subgrade. Therefore, ECRSS is a better measure to mitigate thaw settlement hazards to the railway.

关键词： Qinghai-Tibet railway climate change embankment with crushed rock side slope,numerical analysis thaw settlement

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Fiber-Optic Displacement Sensor Based on the DBR Fiber Laser

引用

Photonic Sensors 2014年第1期4卷 43-47页

作者： guoyu li Yan li Kang Yang Mingsheng liu Institute of Information Technology Handan CollegeHandan056005China

The fiber-optic displacement sensor based on the distributed Bragg reflector fiber laser is proposed, that is, the fiber laser cavity is attached to the measured object, when the measured object is stretched or contracted, and the length of the fiber laser cavity is also stretched or contracted accordingly. In view of the nonlinearity of the fiber-optic displacement sensor, the calibration based on piezoelectric ceramics is applied to improve the linearity of the displacement sensor. Experiment results show that the fiber-optic displacement sensor has a linear response with the nominal working distance of 90 um.

关键词： DBR fiber laser fiber-optic displacement sensor fiber laser cavity FBG

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Properties of sandwich-structure based Mach-Zehnder interferometer cascaded with FBG response to dual-parameter sensing

引用

Optoelectronics Letters 2023年第12期19卷 705-709页

作者： JIA Sumei YANG Kang li guoyu li Yan WANG Zhihui Hebei Key Laboratory of Optical Fiber Biosensing and Communication Devices Institute of Information TechnologyHandan UniversityHandan 056005China

An all-fiber temperature and curvature sensor based on Mach-Zehnder interferometer(MZI)was *** MZI was a sandwich structure which is composed of ring-core fiber(RCF),no-core fiber(NCF)and single-mode fiber(SMF).The temperature and curvature can be demodulated by the wavelength shift and the intensity variation of the dips respectively in the transmission *** measurement results show that the sensitivity of curvature is−7.88 dBm/m^(−1)in the range from 3.0 m^(−1)to 4.2 m^(−1)and the sensitivity of temperature is 53.5 pm/°C in the range from 60°C to 200°*** addition,the cascaded FBG in the proposed structure,also sensitive to temperature,was used to monitor the fluctuation of *** compact structure,the real-time temperature and the high curvature sensitivity make the sensor have the potential in the field of construction health monitoring and mining safety production.

关键词： interferometer fiber cascaded

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Effect of the frozen layer on the stability of cut soil slopes during seasonal freezing and thawing

引用

Research in Cold and Arid Regions 2022年第5期14卷 281-292页

作者： Ting Wang Hailiang Jia Qiang Sun guoyu li College of Geology and Environment Xi'an University of Science and TechnologyXi'anChina College of Architecture and Civil Engineering Xi'an University of Science and TechnologyXi'anChina State Key Laboratory of Frozen Soil Engineering Northwest Institute of Eco-Environment and ResourcesCASLanzhouChina

Research on the stability of soil slopes in seasonally frozen regions has mainly focused on slope failures during the thawing *** are few studies on slope stability during the freezing window and its subsequent influence on slope failure in the next thawing *** this paper,soil strength was tested during freezing and thawing to obtain temperature-dependent strength parameters for the simulation of slope ***,the slope's temperature field over an entire year was accurately simulated so that characteristics of the frozen layer could be determined at any *** on the above results,the progressive failure modes of frozen soil slopes are *** results show that:1)during the freezing window,depth of the frozen soil layer increases,as does the slope's safety factor,while a yield zone propagates towards the slope shoulder.(2)During the thawing window,the frozen soil layer shrinks in depth while the yield zone continuously expands,which decreases the safety *** analysis of these results indicate that the frozen layer provides a“toe-locking effect”that increases the safety factor during the freezing window,while it also provides a“dragging effect”that propagates the yield zone towards the slope *** the thawing window,the“toe-locking effect”gradually diminishes;a continuous sliding surface is formed,which lead to a *** frozen soil layer of the freezing window accelerates the slope sliding in the thawing window.

关键词： Seasonally frozen layer Soil cut slopes Slope stability Stress field Seasonal freezing and thawing

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Dynamic changes in urban land spatial inequality under the core-periphery structure in urban agglomerations

引用

Journal of Geographical Sciences 2023年第4期33卷 760-778页

作者： FANG Xiaoqian SU Dan WU Qing WANG Jiayi ZHANG Yangjian li guoyu CAO Yu Department of Land Management School of Public AffairsZhejiang UniversityHangzhou 310058China Institute of Geographic Sciences and Natural Resources Research CASBeijing 100101China Department of Forestry and Natural Resources Purdue UniversityWest LafayetteIN 47907USA

Relatively coordinated development among cities can typically promote the integration of the whole urban agglomeration,while urbanization of land has been found important to economic development in developing *** studies have measured the urban land expansion in urban ***,urban land spatial inequality under a specific spatial structure remains poorly ***,we combined theβ-convergence model and the core-periphery structure to explore the dynamic changes in urban land spatial inequality in urban *** Yangtze River Delta Urban Agglomeration(YRDUA)in China was selected as the study *** of urban land have been applied in conjunction with a modified conditionalβ-convergence model,while the existence of the core-periphery structure was tested by analyzing coefficients of the control *** results show that although the spatial inequality of urban land area had decreased during 2000–2020,the whole YRDUA had still shown an obvious core-periphery *** with urban land area,the spatial inequality of urban land economic density and population density had decreased more rapidly,and the core-periphery structure was less *** findings can help to improve our current understanding of urban agglomeration and serve as a scientific reference for the coordinated development of urban agglomerations.

关键词： urban agglomeration urban expansion core-periphery structure convergence analysis spatial ine-quality

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Centrifuge model test on performance of thermosyphon cooled sandbags stabilizing warm oil pipeline buried in permafrost

引用

Research in Cold and Arid Regions 2021年第3期13卷 234-255页

作者： guoyu li HongYuan Jing Nikolay Volkov Wei Ma PengChao Chen State Key Laboratory of Frozen Soil Engineering(SKLFSE) Northwest Institute of Eco-Environment and Resources(NIEER)Chinese Academy of Sciences(CAS)LanzhouGansu 730000China Da Xing'anling Observation and Research Station of Frozen-ground Engineering and Environment NIEERCASJiagedaqiHeilongjiang 165000China PipeChina North Pipeline Company LangfangHebei 065000China GEOINGSERVICE LLP(Fugro Group) 29 Vernadskogo AvenueMoscowRussia

The thaw settlement of pipeline foundation soils in response to the operation of the first China-Russia Crude Oil Pipeline along the eastern flank of the northern Da Xing'anling Mountains in Northeast China was simulated in a physical model test(with a similitude ratio of 1/73) in a geotechnical centrifuge. Two pipes of a supported and an unsupported section were evaluated over a testing period for simulating 20 years of actual pipeline operation with seasonal cyclically changing oil and ambient temperatures. The results show that pipe settlement of the supported pipe was 45% of settlement of the unsupported pipe. Settlement for the unsupported section was approximately 35% of the thaw bulb depth below the initial pipe elevation, only 30% of that for the supported pipe due to the influence of the supports. The final thaw bulbs extended approximately 3.6 and 1.6 times of the pipe diameter below the unsupported and supported pipe bottom elevations, respectively. The sandbag supports kept frozen during the test period because of cooling effect of the thermosyphons. The maximum bending stress induced over the 20 m span length from bearing of the full cover over the pipe would be equivalent to40% specified minimum yield strength(SMYS). Potential buckling of the pipe should be considered as the ground *** study also offers important data for calibration and validation of numerical simulation models.

关键词： centrifuge test oil pipeline frost heave thermosyphon thaw settlement permafrost engineering

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Relationship between ponding and topographic factors along the China-Russia Crude Oil Pipeline in permafrost regions

引用

Research in Cold and Arid Regions 2019年第6期11卷 419-427页

作者： MingTang Chai YanHu Mu guoyu li Wei Ma Fei Wang State Key Laboratory of Frozen Soil Engineering Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhouGansu 730000China University of Chinese Academy of Sciences Beijing 100049China

The original landform along the China Russia Crude Oil Pipeline(CRCOP,line 2)was disturbed during installation of pavement for the *** and vegetation coverage is dense,and runoff develops along the *** the opera tion of the CRCOP(line 2)began in 2018,ponding has appeared on both sides of the *** there is no drainage,ponding can hardly dissipate,due to the low permeability of the permafrost *** the supply of surface flow and the transportation of oil at positive temperatures,ponding promotes an increase in temperature and changes the boundary ther mal conditions of the ***,when the ponding freezes and thaws,frost heave threatens operational safety of the ***,the ponding can affect the thermal condition of line *** this paper,the distribution of pond ing along the CRCOP was obtained by field *** type and cause of ponding were summarized,and the catch ment and stream order were extracted by the Digital Elevation Model(DEM).According to the statistical results in attri butes for topographic factors,it is known that ponding along the pipeline is relative to elevation,slope,aspect,and the Topographic Wetness Index(TWI).Water easily accumulates at altitudes of 300450 m,slopes within 3°5°,aspect in the northeast or south,TWI within 1316,flow direction in north east south,and flow length within 90150 *** paper proposes a theoretical basis for the cause and characteristics of ponding along the pipeline.

关键词： permafrost Digital Elevation Model(DEM) Topographic Wetness Index(TWI) pipeline ponding

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Inconsistency of changes in uniaxial compressive strength and P-wave velocity of sandstone after temperature treatments

引用

Journal of Rock Mechanics and Geotechnical Engineering 2021年第1期13卷 143-153页

作者： Jinyuan Zhang Yanjun Shen Gengshe Yang Huan Zhang Yongzhi Wang Xin Hou Qiang Sun guoyu li College of Architecture and Civil Engineering Xi’an University of Science and TechnologyXi’an710054China College of Geology and Environment Xi’an University of Science and TechnologyXi’an710054China Geological Research Institute for Coal Green Mining Xi’an University of Science and TechnologyXi’an710054China State Key Laboratory of Frozen Soil Engineering Cold and Arid Regions Environmental and Engineering Research InstituteChinese Academy of SciencesLanzhou730000China

It is generally accepted that the uniaxial compressive strength(UCS)and P-wave velocity of rocks tend to decrease simultaneously with increasing ***,based on a great number of statistical data and systematic analysis of the microstructure variation of rocks with temperature rising and corresponding propagation mechanism of elastic wave,the results show that(1)There are three different trends for the changes of UCS and P-wave velocity of sandstone when heated from room temperature(20C or 25C)to 800C:(i)Both the UCS and P-wave velocity decrease simultaneously;(ii)The UCS increases initially and then decreases,while the P-wave velocity decreases continuously;and(iii)The UCS increases initially and then fluctuates,while the P-wave velocity continuously decreases.(2)The UCS changes at room temperaturee400C,400Ce600C,and 600Ce800C are mainly attributed to the discrepancy of microstructure characteristics and quartz content,the transformation plasticity of clay minerals,and the balance between the thermal cementation and thermal damage,respectively.(3)The inconsistency in the trends of UCS and P-wave velocity changes is caused by the change of quartz content,phase transition of water and certain minerals.

关键词： Sandstone High temperature Uniaxial compressive strength(UCS) P-wave velocity Distortion Mineralogy

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

A semi-analytical solution for frost heave prediction of clay soil

引用

Research in Cold and Arid Regions 2014年第5期6卷 499-503页

作者： Hui Bing Ying Zhang guoyu li State Key Laboratory of Frozen Soil Engineering Cold and Arid Regions Environmental and Engineering Research InstituteChinese Academy of Sciences

Frost heave is one of the main freezing problems for construction in permafrost *** Konrad-Morgenstern segregation potential（SP） model is being used in practice for frost heave using numerical ***,the heat release from in-situ and migrated water in the freezing zone could result in some numerical instability,so the simulation of frost fringe is not *** this study,a semi-analytical solution is developed for frost heave prediction of clay *** prediction results to the two tests with different freezing mode with clay soil agree well with the tested behavior,which indicates the feasibility of the solution.

关键词： frost heave semi-analytical solution segregation potential clay

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Thermal influence of ponding and buried warm-oil pipelines on permafrost: a case study of the China-Russia Crude Oil Pipeline

引用

Research in Cold and Arid Regions 2020年第2期12卷 59-70页

作者： YanHu Mu MingTang Chai guoyu li Wei Ma Fei Wang YaPeng Cao State Key Laboratory of Frozen Soil Engineering Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhouGansu 730000China University of Chinese Academy of Sciences Beijing 100049China

Buried pipelines are widely used for transporting oil in remote cold regions. However, the warm oil can induce considerable thermal influence on the surrounding frozen soils and result in severe maintenance problems. This paper presents a case study of the thermal influence of ponding and buried warm-oil pipelines on permafrost along the China-Russia Crude Oil Pipeline(CRCOP) in Northeast China. Since its operation in 2011, the operation of the warm-oil pipelines has led to rapid warming and thawing of the surrounding permafrost and development of sizable ponding along the pipeline route,which, in return, exacerbates the permafrost degradation. A field study was conducted along a 400-km long segment of the CRCOP in permafrost regions of Northeast China to collect the location and size information of ponding. A two-dimensional heat transfer model coupled with phase change was established to analyze the thermal influence of ponding and the operation of warm-oil pipelines on the surrounding permafrost. In-situ measured ground temperatures from a monitoring site were obtained to validate the numerical model. The simulation results show that ponding accelerates the development of the thaw bulb around the pipeline. The maximum thaw depth below the pipeline increases from 4 m for the case without ponding to 9 m for the case with ponding after 50 years of operation, and ponding directly above the pipe induces the maximum thaw depth. Engineering measures should be adopted to control the size or even eliminate surface water-rich ponding for the long-term performance of buried warm-oil pipelines.

关键词： ponding heat transfer modeling oil pipeline permafrost thaw depth

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：