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Direct shear tests of coarse-grained fillings from high-speed railway subgrade in cold regions

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Research in Cold and Arid Regions 2017年第3期9卷 236-242页

作者： Qing Zhi Wang jian kun liu jian Hong Fang An Hua Xu School of Civil Engineering Beijing Jiaotong University Qinghai Research Institute of Transportation

In order to study the shear behavior of coarse-grained fillings taken from the subgrade bottom layer of a cold region high-speed railway,large scale direct shear tests were conducted with different normal pressures,water contents and *** results indicate that the relationship between shear displacement and shear stress changed from strain-softening at lower normal pressures to strain-hardening at higher normal pressures,in both unfrozen and frozen *** phenomenon was mainly due to the shear dilatation deformation *** shear displacement-shear stress curves show similar ***,the shear stress rapidly increased and there was not an increment in the shear displacement during the initial stage of the shear process in the frozen *** both the unfrozen or frozen states at the same water contents,the shear strength increased with increasing normal pressure.

关键词： coarse-grained fillings large scale direct test shear displacement-shear stress curve shear strength

Deformation properties of chloride saline soil under action of a low-temperature environment and different loads

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Research in Cold and Arid Regions 2017年第3期9卷 307-311页

作者： Yu Zhang jian kun liu jian Hong Fang An Hua Xu Lanzhou Jiaotong University School of Traffic and Transportation Beijing Jiaotong University School of Civil Engineering Qinghai Research Institute of Transportation

To find the deformation properties of chloride saline soil under the influence of a low temperature environment and different loads,two types of chloride saline soil were selected and their deformation process was tested in the laboratory and analyzed during the cooling process in the sensitive cryogenic temperature *** research results show that high-chloride-salt saline soil underwent little volume change under the no-load condition during the cooling *** staticload and dynamic-load conditions,different degrees of settlement deformation occurred;throughout the entire cooling process,another chloride saline soil with a high proportion of sulfate salt underwent volume expansion under no-load and static-load *** the no-load condition,a certain degree of settlement deformation *** properties were evaluated at different time points during the cooling process for two kinds of chloride saline ***,deformation characteristics of chloride saline soil were analyzed from the perspective of salt type and crystallization variation under the action of a low-temperature environment and different loads.

关键词： saline soil low temperature loads deformation cooling process

Elastoplastic behavior of frozen sand-concrete interfaces under cyclic shear loading

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2022年第9期23卷 683-703页

作者： jian CHANG jian-kun liu Ya-li LI Qi WANG Zhong-hua HAO School of Civil Engineering Beijing Jiaotong UniversityBeijing 100044China School of Civil Engineering Sun Yat-sen UniversityZhuhai 519082China Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai) Zhuhai 519082China

The resilient modulus,accumulated plastic strain,peak shear stress,and critical shear stress are the elastoplastic behaviors of frozen sand–concrete interfaces under cyclic shear *** reflect the bearing capacity of buildings(*** railways)in both seasonal frozen and permafrost *** study describes a series of direct shear experiments conducted on frozen sand–concrete *** results indicated that the elastoplastic behaviors of frozen sand–concrete interfaces,including the resilient modulus,accumulated plastic strain,and shear strength,are influenced by the boundary conditions(constant normal loading and constant normal height),initial normal stress,negative temperature,and cyclic-loading *** resilient modulus was significantly correlated with the initial normal stress and negative temperature,but not with the cyclic-loading amplitude and loading *** accumulated plastic shear strain increased when the initial normal stress and cyclic-loading amplitude increased and the temperature ***,the accumulated plastic shear strain increment decreased when the loading cycles *** accumulated direction also varied with changes in the initial normal stress,negative temperature,and cyclic-loading *** peak shear stress of the frozen sand–concrete interface was affected by the initial normal stress,negative temperature,cyclic-loading amplitude,and boundary ***,a correlation was observed between the critical shear stress and the initial normal stress and boundary *** peak shear stress was higher,and the critical shear stress was lower under the constant normal height boundary *** on the results,it appears that the properties of frozen sand–concrete interfaces,including plastic deformation properties and stress strength properties,are influenced by cyclic shear *** results provide valuable information for the investigation of constitutive models of f

关键词： Frozen sand-concrete interface Cyclic direct shear test Elastoplastic behavior Direction of accumulated plastic strain Boundary condition

Experimental study of the dynamic behavior of high-grade highway-subgrade soil in a seasonally frozen area

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Research in Cold and Arid Regions 2017年第3期9卷 289-296页

作者： Hong Huan Cui Yu Tao Ma jian kun liu Zhi Yang Wang School of Civil Engineering Hebei University of Architecture School of Civil Engineering Beijing Jiaotong University

Regarding the freezing damage of high-grade highway subgrade in seasonally frozen area,the thesis explores the effect on the dynamic behavior of subgrade soil under freeze–thaw cycles and draws the change law of parameters(including dynamic strength,dynamic cohesion,and internal friction angle;and dynamic elastic modulus)of high-grade highway-subgrade soil with the number of freeze–thaw *** aims to provide the reference for operation and maintenance of a high-grade ***:(1)Dynamic strength tends to decline evidently after freeze–thaw cycles,with 60%~70%decline after three cycles,and remains stable after five to seven cycles.(2)With the number of freeze–thaw cycles increasing,the internal friction angle fluctuates within a certain range without an obvious change law,only presenting the tendency of dropping *** dynamic cohesion declines obviously,about 20%~40%after seven freeze–thaw cycles,and then tends to be stable.(3)With the number of freeze-thaw cycles increasing,the dynamic elastic modulus and maximum dynamic elastic modulus are inclined to decrease *** five freeze–thaw cycles,the former declines 30%~40%and then remains ***,the latter falls 20%~40%.

关键词： seasonally frozen area freeze-thaw cycle dynamic behavior dynamic triaxial test high-grade highway-subgrade soil

季节性冻土区光伏支架螺旋桩抗冻拔试验研究（英文）

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2016年第7期17卷 512-524页

作者： Teng-fei WANG jian-kun liu Hua-gang ZHAO Ya-long SHANG Xiao-qiang liu School of Civil Engineering Beijing Jiaotong University North China Power Engineering Co. Ltd.of China Power Engineering Consulting Group

目的:基于相似性原理,模拟实际工况中的降温冻结过程;通过室内试验确定最优桩型,并推导冻拔量与冻深的定量关系。创新点:1.进行季节性冻土区螺旋桩的自由冻胀试验;2.根据相似性原理,在室内试验过程中调整冷端温度与几何尺寸以缩短冻结时... 详细信息

目的:基于相似性原理,模拟实际工况中的降温冻结过程;通过室内试验确定最优桩型,并推导冻拔量与冻深的定量关系。创新点:1.进行季节性冻土区螺旋桩的自由冻胀试验;2.根据相似性原理,在室内试验过程中调整冷端温度与几何尺寸以缩短冻结时间;3.推导得到6种桩型冻拔量与冻结深度的定量关系。方法:1.通过相似性原理确定试验条件,模拟实际工况中的降温冻结过程;2.观测此过程中5种螺旋桩型的温度场、冻拔量和土压力随时间的变化规律,并设置一组光滑桩作为对比;3.根据冻拔量大小选取最优桩型,并推导冻拔量与冻深的定量关系。结论:1.螺旋桩冻拔量小于光滑桩,验证了螺旋桩抗冻拔的有效性;采用不同土样有相同规律。2.冻深达到0.9 m的季冻区,双螺旋大叶片桩抗冻拔效果最好;螺旋叶片建议设置在非冻区;冻拔量大小关系为:双螺旋大叶片桩<半螺旋大叶片桩<半螺旋小叶片桩<双螺旋小叶片桩<全螺旋桩<光滑桩。3.得到6种桩型冻拔量与冻深的线性关系。4.土中水开始冻结时土压力增大,含冰量稳定后土压力变化很小。

关键词：季节性冻土区螺旋桩冻胀相似性原理冻拔

Using attributes of electromagnetic waves to determine the water content and frost table in a permafrost area

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Research in Cold and Arid Regions 2017年第3期9卷 261-266页

作者： Zhi Chun Zhang Yu Peng Shen Xiao Wang Ya Hu Tian jian kun liu Bagdat Teltayev Shen-Shuo Railway Branch China Shenhua Energy Company Limited School of Civil Engineering Beijing Jiaotong University Kazakhstan Highway Research Institute

The thawing-melting of the permafrost damages the subground of highways on the Qinghai-Tibet *** the application of ground-penetrating-radar(GPR)technology,the maximum permafrost melting interface can be effectively distinctly differentiated and imaged.A hierarchical feature of the permafrost region is shown clearly on the imaging profile of GPR *** complete ablation zone or part of it is displayed *** addition,the details of subsurface layers can be effectively characterized by GPR attribute-analysis *** the attribute calculation and filter,the instantaneous amplitude,instantaneous frequency,and relative wave impedance can be applied in a more efficient way to divide the complete ablation zone,part of the ablation and non-ablation *** relative distribution of water content in a seasonally thawing permafrost region can be obtained through a comprehensive GPR attribute analysis.

关键词： permafrost thawing ground-penetrating-radar geophysical attribute relative water content

冻结环境温度对粉质黏土冻融循环效应影响的试验（英文）

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长安大学学报（自然科学版） 2017年第4期37卷 41-49页

作者：胡田飞刘建坤刘大伟北京交通大学土木建筑工程学院北京100044

为明确冻结过程中环境温度对土体冻融循环效应的影响规律,以青藏高原粉质黏土为对象,首先选择冻结环境温度(-5℃、-10℃、-15℃、-20℃、-25℃、-30℃)和冻融循环次数(0、1、3、6、9、12、15)为变量进行了一系列冻融循环试验,然后,以围... 详细信息

为明确冻结过程中环境温度对土体冻融循环效应的影响规律,以青藏高原粉质黏土为对象,首先选择冻结环境温度(-5℃、-10℃、-15℃、-20℃、-25℃、-30℃)和冻融循环次数(0、1、3、6、9、12、15)为变量进行了一系列冻融循环试验,然后,以围压(50、100、150kPa)为变量,对经历冻融循环试验后的试样进行三轴压缩试验。研究结果表明:冻结环境温度会显著影响土体经历冻融循环后的物理力学性质。冻融循环后试样的破环强度整体上有所减小,并随冻结环境温度的降低呈先减小、后增大的变化规律,-15℃时破坏强度达谷值。虽然土体冻结后的表观体积增大,但膨胀变形分量和收缩变形分量在冻结过程中同时存在,而且随着环境温度的降低,冻胀先于冻缩达到极限状态,因此表观体积呈先增大、后减小的变化规律,相应地破坏强度呈相反的变化规律。此外,随着冻融循环次数的增加,破坏强度呈先减小、后逐渐稳定的变化规律。同时,冻结环境温度越低,破坏强度达到稳定值所需的冻融循环次数越少。试样冻结过程中的水分迁移速率和迁移量随环境温度的降低而减小,水分迁移对土体结构的影响也随之减小。抗剪强度指标表现为与破坏强度一致的冻融循环效应,其中内摩擦角对冻结环境温度变化的响应程度大于黏聚力的影响程度。

关键词：道路工程冻土冻融循环冻结温度破坏强度抗剪强度冻缩

The Numerical Simulation of Field Enhancement in Near-Field Scanning Raman Microscopy

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The Numerical Simulation of Field Enhancement in Near-Field ...

Multiple liver metastases of unknown origin:A case report

Photonics Asia 2004;Optoelectronics,Microelectronics,and Nanotech

作者： Yaqin Li*, Shifa Wu, Guoshu jian, kun liu Physical department of Dalian University of Technology, Dalian, 116024

The combination of plasmon near-field scanning optical microscopy (PNSOM) and Raman spectroscopy named Near-field Scanning Raman Microscopy (SNRM) provides not only surface topography information but

关键词： SERS, FDTD, “hot spot”, field enhancement, evanescent wave

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World Journal of Gastrointestinal Oncology 2025年第1期17卷 233-238页

作者： Ying-Jin Wang Ze-Chuan liu jian Wang Yin-Mo Yang Department of Hepatobiliary Pancreatic Surgery Peking University First HospitalBeijing 100034China Department of Interventional and Vascular Surgery Peking University First HospitalBeijing 100034China

BACKGROUND The liver is the most common site of digestive system tumor metastasis,but not all liver metastases can be traced back to the primary *** it is unusual,syphilis can impact the liver,manifesting as syphilitic hepatitis with inflammatory nodules,which might be misdiagnosed as *** SUMMARY This case report involves a 46-year-old female who developed right upper abdominal pain and intermittent low fever that persisted for more than three *** definitive diagnosis of a tumor had been made in the past decades,but signs of multiple liver metastases were recognized after a computed tomo-graphy scan without evidence of primary *** positive serological tests for syphilis and a biopsy of the liver nodules,a diagnosis of hepatic syphilis was made and confirmed with follow-up nodule reduction after anti-syphilis *** Clinicians must be aware of the possibility that syphilis can cause hepatic inflam-matory masses,especially when liver metastasis is suspected without evidence of primary lesions.A definitive diagnosis should be established in conjunction with a review of the patient’s medical history for accurate therapeutic intervention.

关键词： Syphilitic hepatitis Liver nodules Liver metastasis Treponema pallidum Case report