Numerical tests on dynamic response of pile-supported reclaimed embankment for high-speed railway in saturated soft ground using soil–water coupling elastoplastic FEM

IF 4.9 2区 工程技术 Q1 ENGINEERING, CIVIL
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Abstract

High-speed train (HST) running in the saturated soft ground induces significant vibration that may threaten the running safety and serviceability of high-speed railway (HSR). Extensive studies have been conducted on the dynamic responses of HSR, yet, the soil–water coupling and plastic behavior in the saturated soft ground are rarely considered, and thus the build-up of excess pore water pressure (EPWP) and displacement cannot be accurately calculated. In this study, 2D soil–water coupling elastoplastic FEM was employed to investigate HST induced vibration in the pile-supported embankment using FE code called DBLEAVES. Dynamic soil stress, EPWP, acceleration and displacement under different cases were numerically analyzed in detail. Numerical tests confirm that liquid phase in soft ground plays important influence on the dynamic responses that vertical acceleration and displacement will be overestimated while the horizontal acceleration and displacement as well as EPWP will be underestimated if soil–water coupling is not considered. Single-phase analysis also exaggerates the acceleration attenuation and underestimate the vibration amplification in soft ground. The existence of piles can induce significant soil arching effect in the embankment, the distributions of vertical acceleration and EPWP are partitioned sharply by the piles while vertical displacement in soft ground becomes more uniform along the depth direction within the pile reinforced area. The existence of piles also induces stronger vibration beneath the pile end so that larger EPWP is generated below the pile end than around the pile body. The main influence area due to HST vibration for pile-supported embankment is overall 20 m away from the centerline of HSR track, therefore, it is reasonable to improve the ground by properly increasing the number of pile within this area. When the number of pile is determined, increasing the length of pile or reducing the pile spacing are two effective ways to mitigate the dynamic response.
利用土水耦合弹塑性有限元对饱和软土地基中高速铁路桩基支撑填海路堤的动态响应进行数值试验
高速列车(HST)在饱和软土地基上运行时会产生明显的振动,这可能会威胁到高速铁路(HSR)的运行安全和适用性。人们对高速铁路的动态响应进行了大量研究,但很少考虑饱和软土地基中的土水耦合和塑性行为,因此无法准确计算过剩孔隙水压力(EPWP)的积累和位移。本研究采用二维土水耦合弹塑性有限元,利用名为 DBLEAVES 的有限元代码研究了 HST 诱导的桩基路堤振动。对不同情况下的土体动应力、EPWP、加速度和位移进行了详细的数值分析。数值试验证实,软土地基中的液相对动力响应有重要影响,如果不考虑土水耦合,垂直加速度和位移会被高估,而水平加速度和位移以及 EPWP 则会被低估。单相分析还会夸大加速度衰减,低估软土地基的振动放大。桩的存在会在路堤中引起明显的土拱效应,垂直加速度和 EPWP 的分布被桩急剧分割,而软土地基中的垂直位移在桩加固区域内沿深度方向变得更加均匀。桩的存在也会引起桩端下方更强烈的振动,因此桩端下方产生的 EPWP 要大于桩身周围。桩基加固路堤受 HST 振动的主要影响范围是距高铁轨道中心线 20 米处,因此在此范围内适当增加桩基数量以改善地基是合理的。在确定桩数后,增加桩长或减小桩间距是减轻动态响应的两种有效方法。
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来源期刊
Transportation Geotechnics
Transportation Geotechnics Social Sciences-Transportation
CiteScore
8.10
自引率
11.30%
发文量
194
审稿时长
51 days
期刊介绍: Transportation Geotechnics is a journal dedicated to publishing high-quality, theoretical, and applied papers that cover all facets of geotechnics for transportation infrastructure such as roads, highways, railways, underground railways, airfields, and waterways. The journal places a special emphasis on case studies that present original work relevant to the sustainable construction of transportation infrastructure. The scope of topics it addresses includes the geotechnical properties of geomaterials for sustainable and rational design and construction, the behavior of compacted and stabilized geomaterials, the use of geosynthetics and reinforcement in constructed layers and interlayers, ground improvement and slope stability for transportation infrastructures, compaction technology and management, maintenance technology, the impact of climate, embankments for highways and high-speed trains, transition zones, dredging, underwater geotechnics for infrastructure purposes, and the modeling of multi-layered structures and supporting ground under dynamic and repeated loads.
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