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Performance of composite foundations with different load transfer platforms and substratum stiffness over silty clay

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Journal of Mountain Science 2024年第5期21卷 1761-1774页

作者： ZHANG Shuming LIU Yan YUAN Shengyang LIU Xianfeng jiang guanlu LIU Junyan School of Civil Engineering and Architecture University of JinanJinan 250022China The Engineering Technology Research Center for Urban Underground Engineering Supporting and Risk Monitoring of Shandong Province Jinan 250022China School of Civil Engineering Southwest Jiaotong UniversityChengdu 610031China Key Laboratory of High-speed Railway Engineering Ministry of EducationSouthwest Jiaotong UniversityChengdu 610031China

The semi-rigid pile-supported composite foundation is widely used in highway projects due to its effectiveness in increasing the bearing capacity and stability of *** is crucial to understand the stress distribution across the embankment width and the behaviour of unreinforced ***,five centrifuge tests were conducted to examine the bearing and deformation behaviours of NPRS(Non-Connected Piled Raft Systems)and GRPS(GeosyntheticReinforced Pile-Supported systems)with varying substratum stiffness,then a comparative analysis was conducted on embankment settlement,pressures underneath the embankments,and axial forces along the *** results indicated that greater substratum stiffness correlates with reduced settlement and deformation at various *** occurring 5 meters from the embankment toe includes settlement in NPRS and upward movement in *** potential sliding surface is primarily located within the embankment in NPRS,whereas it may extend through both the embankment and foundation in *** pile-soil stress ratio and efficiency in NPRS are higher than in GRPS across the *** axial force borne by end-bearing piles is significantly greater than that by floating *** the buried depth increases,the axial force in GRPS initially rises then declines,whereas in NPRS,it remains relatively constant within a certain range before *** study aids in assessing the applicability of composite foundations in complex railway environments and provides a reference for procedural measures under similar conditions.

关键词： Centrifuge modelling Composite foundation Failure mode Load transfer platform Substratum Stiffness Silty clay

Dynamic response and failure process of horizontal-layered fractured structure rock slope under strong earthquake

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Journal of Mountain Science 2024年第3期21卷 882-900页

作者： WANG Tong LIU Xianfeng HOU Zhaoxu XU Jiahang ZHANG Jun YUAN Shengyang jiang guanlu HU Jinshan School of Civil Engineering Southwest Jiaotong UniversityChengdu 610031China Key Laboratory of High-Speed Railway Engineering of Ministry of Education Southwest Jiaotong UniversityChengdu 610031China School of Civil Engineering Xinjiang Institute of EngineeringUrumqi 830023China China Railway First Survey and Design Institute Group Co.LTD Xi'an 710043China

Rock slope with horizontal-layered fractured structure(HLFS)has high stability in its natural ***,a strong earthquake can induce rock fissure expansion,ultimately leading to slope *** this study,the dynamic response,failure mode,and spectral characteristics of rock slope with HLFS under strong earthquake conditions were investigated based on the large-scale shaking table model *** this basis,multiple sets of numerical calculation models were further established by UDEC discrete element *** influencing factors were considered in the parametric study of numerical simulations,including slope height,slope angle,bedding-plane spacing and secondary joint spacing as well as bedrock dip *** results showed that the failure process of rock slope with HLFS under earthquake action is mainly divided into four phases,i.e.,the tensile crack of the slope shoulder joints and shear dislocation at the top bedding plane,the extension of vertical joint cracks and increase of shear displacement,the formation of step-through sliding surfaces and the instability,and finally collapse of fractured rock *** acceleration response of slopes exhibits elevation amplification effect and surface *** simulations indicate that the seismic stability of slopes with HLFS exhibits a negative correlation with slope height and angle,but a positive correlation with bedding-plane spacing,joint spacing,and bedrock dip *** results of this study can provide a reference for seismic stability evaluation of weathered rock slopes.

关键词： Seismic behavior Horizontal layered Weathered rock slope Shaking table test Failure mode

基于声发射参数分析的红层泥岩高周循环加卸载损伤及变形特性

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中国铁道科学 2024年第1期45卷 12-25页

作者：于天佑蒋关鲁饶千竺陈虹羽吴霖刘先峰西南交通大学土木工程学院四川成都610031 西南交通大学高速铁路线路工程教育部重点工程实验室四川成都610031 新疆工程学院土木工程学院新疆乌鲁木齐830023

为研究不同应力上限及加载频率条件下软弱红层泥岩的损伤及变形特性,基于声发射损伤监测手段开展高周循环加卸载试验,系统分析应力上限与加载频率对红层泥岩损伤及裂纹扩展模式的影响。结果表明:当应力上限低于屈服临界动应力值时,泥岩... 详细信息

为研究不同应力上限及加载频率条件下软弱红层泥岩的损伤及变形特性,基于声发射损伤监测手段开展高周循环加卸载试验,系统分析应力上限与加载频率对红层泥岩损伤及裂纹扩展模式的影响。结果表明:当应力上限低于屈服临界动应力值时,泥岩经历先剪缩后缓慢剪胀的过程,岩样中微裂隙的发展与黏土矿物的膨胀逐渐占据主导地位;低频AE信号产生于静载阶段,而高频AE信号主要出现在循环加载阶段,且随加载频率的增大,超过300 kHz的超高频声AE信号占比逐渐增大;红层泥岩循环荷载下所产生的裂纹总体以张拉裂纹为主,但第I阶段剪切裂纹占比相对其他阶段较大,且随着动应力幅值减小或加载频率的增大,剪切裂纹所占比例减小;在裂隙自愈合效应下,泥岩中由动载引起的损伤裂隙会被逐渐修复,且随着放置时间的增加,声发射Kaiser效应逐渐减小甚至消失。

关键词：红层泥岩循环荷载声发射参数分析裂纹扩展模式裂隙自愈合效应

框架梁与锚索桩板墙加固隧道洞口边坡的动力响应特性

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中国铁道科学 2024年第2期45卷 134-145页

作者：冯海洲蒋关鲁何梓雷郭玉丰何晓龙刘先峰胡金山西南交通大学土木工程学院四川成都610031 西南交通大学高速铁路线路工程教育部重点实验室四川成都610031 中铁第一勘察设计研究院有限公司陕西西安710043

针对山岭隧道洞口在降雨、地震等因素作用下易产生变形破坏的问题,以某处采用框架梁与锚索桩板墙支护的隧道洞口边坡工程为原型,开展几何比尺为1∶50的振动台模型试验,分析降雨后地震作用下边坡的动力响应特性及失稳变形规律。结果表明... 详细信息

针对山岭隧道洞口在降雨、地震等因素作用下易产生变形破坏的问题,以某处采用框架梁与锚索桩板墙支护的隧道洞口边坡工程为原型,开展几何比尺为1∶50的振动台模型试验,分析降雨后地震作用下边坡的动力响应特性及失稳变形规律。结果表明:降雨后坡面无局部破坏,地震作用下边坡的破坏过程可归纳为坡顶张拉破坏—坡脚剪切溃裂—坡体整体失稳滑动,边坡表现为张拉—剪切型破坏;边坡峰值加速度放大系数呈层状分布,“高程效应”与“趋表效应”显著,均随输入正弦波频率、幅值的增加而增大;边坡土体峰值应变分布与坡体滑动破坏面较吻合;桩体锚索轴力与输入正弦波频率、幅值呈正相关,强震作用下锚索轴力增幅显著;桩后峰值土压力近似呈三角形分布,桩体嵌固段内桩土压力最大;桩体弯矩呈“b”型分布,嵌固段内桩体峰值弯矩最大,抗震设计中应注意验算其抗弯强度;桩后土压力与桩体加速度FFT谱幅值主要集中于低频段,结构动力响应主要受地震波低频段部分影响。

关键词：隧道洞口边坡框架梁锚索桩板墙降雨地震动力响应振动台试验

Comparison of Seismic Design Codes between China and the United States for Reinforced Soil Retaining Walls

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Earthquake Research in China 2019年第1期33卷 147-152页

作者： XU Peng TIAN Hongcheng jiang guanlu WANG Zhimeng School of Civil Engineering Southwest Jiaotong University Key Laboratory of High-Speed Railway Engineering Ministry of Education China Railway Eryuan Engineering Group Co. Ltd.

Because of its excellent seismic performance, reinforced soil retaining walls are increasingly used in civil engineering. Although many countries have published corresponding design codes, the differences between them are still relatively large. Using the FHWA Code and the Code for Seismic Design of Railway Engineering(CSDRE), stability calculations of reinforced soil retaining walls were carried out and the similarities and differences between these two design codes were analyzed. According to the comparative analysis, the following conclusions are drawn: the inertia force, the earth pressure and the tensile force of reinforcements calculated from the CSDRE are less than those from the FHWA Code, and the safety factor calculated from the former is larger. Although the M-O method is recommended to calculate the dynamic earth pressure, the FHWA Code suggests a higher action point as compared to the CSDRE.

关键词： Seismic performance Reinforced soil retaining wall Inertia force Earth pressure Tensile force

A test method for analyzing the deformation of landslide model

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Earthquake Research Advances 2021年第3期1卷 46-52页

作者： Da Lei Mingjie Chen Zhihao Xu Bin Luo guanlu jiang Kai Fan Qihao Zhou College of Civil Engineering Sichuan Agricultural UniversityDujiangyan611830China Sichuan Higher Education Engineering Research Center for Disaster Prevention and Mitigation of Village Construction Dujiangyan611830China School of Civil Engineering Southwest Jiaotong UniversityChengdu610031China

In order to study the overall deformation of geotechnical model conveniently,the worksite of landslide bridge foundation reinforced by the front and rear row anti-slide piles in Chenglan railway was taken as an *** the basis of shaking tabe test of a 1/40 reduced scale model,the landslide deformation caused by vibration waves was monitored through burying self-made phosphor bronze strips in *** with the horizontal and vertical coordinates of the bending strain points on the phosphor bronze strips,the digital matrix was converted by applying Renka Cline random matrix generation method,and the two-dimensional contour plots were drawn based on *** results showed that the two-dimensional contour plots reflected the basic law of landslide deformation reasonably,and it revealed the evolution process of landslide deformation and *** research conclusions were consistent with the test phenomenon,which met the basic requirements of overall deformation analysis of landslide *** proposed method can monitor multiple cross sections and was practical for model test.

关键词： Landslide Soil deformation Shaking table test Phosphor bronze strip Two-dimensional contour plot

Shaking Table Test Study on Dynamic Characteristics of Bridge Foundation Reinforcement on Slopes

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Earthquake Research in China 2017年第3期31卷 403-413页

作者： Lei Da Qi Zhihui jiang guanlu Wang Zhimeng Li Anhong School of Civil Engineering Southwest Jiaotong UniversityChengdu 610031China Key Laboratory of High-Speed Railway Engineering Ministry of EducationChengdu 610031China China Railway Eryuan Engineering Group Co.Ltd. Chengdu 610031China

With the fast development of bridge construction in mountainous and seismic areas,it is necessary to conduct related research. Based on the design of a shaking table model test,here are the following test results: the filtering effect exists in soil and is affected by the dynamic constraint conditions,the amplitude is strengthened around the natural frequency and weakened in other frequency bands in the Fourier spectrum. Since the acceleration scaling effect occurred on a sloped surface,the acceleration response decreases from the outside to the inside in soil. The dynamic response is relatively strong near the slip surface in bedrock due to the reflection of seismic waves. The failure mode of landslide is decided by the slope angle and slipping mass distribution, and the test shows the front row stabilizing piles should keep a proper distance from bridge foundation so that seismic resistance can be guaranteed for the bridge foundation.

关键词： Shaking table test Stabilizing pile Filtering effect Dynamic response Failure mode

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CFG桩桩-网结构地基抗液化性能数值分析

中国铁道科学 2008年第5期29卷 1-6页

作者：詹永祥蒋关鲁重庆大学土木工程学院重庆400030 西南交通大学土木工程学院四川成都610031

以京沪高速铁路液化土地基加固为背景,采用数值分析方法,通过各级加载情况下地基路基加固前后液化区域分布及超静孔隙水压力变化规律的分析,对水泥粉煤灰碎石桩(CFG桩)桩-网结构地基加固饱和粉土地基进行抗液化性能研究。研究表明,未加... 详细信息

以京沪高速铁路液化土地基加固为背景,采用数值分析方法,通过各级加载情况下地基路基加固前后液化区域分布及超静孔隙水压力变化规律的分析,对水泥粉煤灰碎石桩(CFG桩)桩-网结构地基加固饱和粉土地基进行抗液化性能研究。研究表明,未加固饱和粉土地基在加载加速度大于0.2g时,几乎全部液化;加固后饱和粉土地基在加速度幅值为0.1g时,加固区以外的饱和粉土地基面附近有小面积的液化,随着加载加速度的增大,加固区以外的饱和粉土地基面积液化进一步加大,并逐渐向桩间土发展,当加速度幅值达到0.4g时,路基发生完全液化;超静孔隙水压力随加载加速度幅值的增加而增大。CFG桩桩-网结构地基能够有效地抑制超静孔隙水压力的上升,从而提高地基的抗液化能力。

关键词：地基饱和粉土液化 CFG桩桩-网结构地基数值分析

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基于离心模型试验的地基附加应力修正

西南交通大学学报 2015年第4期50卷 662-668页

作者：吴丽君蒋关鲁李安洪成都理工大学地质灾害防治与环境保护国家重点实验室四川成都610059 西南交通大学土木工程学院四川成都610031 中国中铁二院工程集团有限责任公司四川成都610031

为提高对路基沉降的精度控制,对2种中等压缩性土地基在路基自重作用下的地基附加应力分布规律进行了离心模型试验,并通过PLAXIS2D有限元数值计算和现场测试参数反算地基附加应力进行了验证.基于试验结果,提出了考虑路基宽高比影响的路... 详细信息

为提高对路基沉降的精度控制,对2种中等压缩性土地基在路基自重作用下的地基附加应力分布规律进行了离心模型试验,并通过PLAXIS2D有限元数值计算和现场测试参数反算地基附加应力进行了验证.基于试验结果,提出了考虑路基宽高比影响的路基中心处地基附加应力修正计算方法.研究结果表明:在路基荷载作用下,附加应力在浅层地基中衰减较快,随地基深度增大,衰减逐渐减慢,与Boussinesq解得到的地基附加应力衰减曲线存在显著差异;修正方法计算的地基附加应力与现场测试参数的反算结果基本吻合.

关键词：地基附加应力中等压缩性土路基宽高比离心模型试验现场试验