考虑土体强度参数随机场的横向加载管-土相互作用分析

Analysis of pipe-soil interaction under lateral loads using random fields of soil strength parameters

  • 摘要: 输水管道受滑坡、地震、断层活动等影响将产生横向运动,埋地管道的管-土相互作用问题可归结于管-土接触界面的接触压力研究。基于Abaqus有限元模拟及其二次开发功能,通过土体强度参数随机场模拟土体非均质性,研究受横向荷载的埋地管道与土体之间相互作用,并对3种变异系数工况进行模拟;将模拟结果与均质土条件的确定性结果进行对比,对随机分析模拟结果进行参数分析及概率研究。研究表明:所提方法可以较好地模拟横向荷载条件下管-土相互作用;土体抗剪强度空间变异条件下的管-土结构承载力小于确定性分析结果,土体非均质性对横向荷载作用下浅埋管道破坏机制的影响表现为土体破坏沿强度薄弱的区域发展;土体不排水抗剪强度随机参数水平相关距离对管-土结构承载力影响显著;管道达预设位移时管-土结构承载力服从对数正态分布;考虑工程容许荷载设计,随着安全系数的增大,管-土结构失效概率显著减小,当安全系数取2.5时失效概率小于1%,达到工程可靠水平。

     

    Abstract: This study presents a comprehensive method for investigating the interaction between buried pipelines and soil under lateral loads, considering factors such as landslides, earthquakes, fault activity, and other sources of lateral movement. By employing Abaqus finite element simulation and its secondary development function, the study focuses on analyzing the contact pressure at the pipe-soil interface, which plays a crucial role in understanding the problem of pipe-soil interaction. To account for soil heterogeneity, the study utilizes a random field approach to simulate the variability of soil strength parameters. Three different coefficients of variation representing various working conditions are considered for a single buried pipeline configuration. The simulation results are compared with deterministic results obtained under homogeneous soil conditions. Additionally, parameter analysis and probability research are conducted to investigate the stochastic analysis simulation results. The findings reveal that the proposed method effectively captures the pipe-soil interaction under lateral loads. The bearing capacity of the pipe-soil structure interaction is found to be lower when soil shear strength exhibits spatial variability compared to deterministic analysis results. The influence of soil heterogeneity on the failure mechanism of shallow buried pipelines under lateral load is observed as soil failure occurring in areas with weak strength. Furthermore, the horizontal correlation distance of random parameters for soil undrained shear strength significantly affects the bearing capacity of the pipe-soil structure interaction. The bearing capacity follows a lognormal distribution when the pipeline reaches the preset displacement. Considering engineering design standards, the failure probability of the pipe-soil structure decreases considerably with an increase in the safety factor. A safety factor of 2.5 ensures a failure probability of less than 1%, which meets the desired level of engineering reliability.

     

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