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新建下穿道路致高铁桥墩位移的时变响应面研究

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为解决新建下穿道路引起邻近既有高铁桥墩位移变化难以精准预测的问题,建立土体-桥梁-轨道的一体化空间时变有限元模型.采用修正Morris方法分析高铁桥墩位移对土体参数和道路设计参数的敏感性,提出时变响应面函数的简化拟合方法.基于Box-Behnken Design(BBD)进行试验设计,分2个阶段拟合了4种桥墩位移与敏感参数的时变响应面函数;根据时变响应面构建结构功能函数,采用蒙特卡罗法对参数进行107次随机抽样,计算高铁桥墩竖向位移的可靠概率.研究结果表明:新建道路下穿软土地区32 m跨度的高铁简支梁桥时,主要持力土层的回弹曲线斜率、泊松比和新建道路的路基高度、宽度等参数为影响高铁桥墩竖向位移的敏感参数.本文提出的中墩竖向位移的时变响应面函数简化效率高达80%左右,时变响应面函数对土层固结不同时刻的墩顶位移预测值与有限元计算值极为接近,相对误差在2%以下,响应面函数预测精度良好.地基土层固结过程中,最不利的中墩竖向位移小于规范限值的可靠概率高达99.9%;地基土层固结稳定时,最不利的中墩竖向位移为1~1.8 mm的概率较大.本文考虑了土层力学参数的时变性和离散性,通过时变响应面函数计算地基土层固结过程中既有高铁桥墩位移及其可靠概率,为今后类似新建工程致既有桥墩位移的简化计算提供参考.
Study on the time-varying response surface of high-speed railway pier displacement caused by new underpass road
In order to solve the problem that it is difficult to accurately predict the displacement change of adjacent high-speed railway piers caused by the new underpass road,this paper established an integrated space-time-varying finite element model of soil-bridge-track,analyzed the sensitivity of the displacement of high-speed rail bridge piers to soil parameters and road design parameters by using the modified Morris method,proposed a simplified fitting method for time-varying response surface functions,and carried out experimental design based on Box-Behnken Design(BBD).Four time-varying response surface functions of pier displacements and sensitive parameters were fitted in two stages.The structural function was constructed based on the time-varying response surface,and the Monte Carlo method was used to randomly sample the parameters for 107 times to calculate the reliable probability of vertical displacement of high-speed rail piers.The results show that when the new road passes under the 32 m span of the high-speed rail simple supported girder bridge in the soft soil area,the rebound curve slope and the Poisson's ratio of the main bearing strata soil,and the subgrade height and width of the new road are the sensitive parameters affecting the vertical displacement of the high-speed rail pier.The simplified efficiency of the time-varying response surface function of the vertical displacement of the middle pier proposed in this paper is as high as about 80%,and the prediction value of the time-varying response surface function for the displacement of the pier top at different times of soil consolidation is very close to the calculated value of the finite element.The relative error is less than 2%,and the prediction accuracy of the response surface function is satisfactory.In the process of soil consolidation,the reliable probability that the vertical displacement of the most unfavorable middle pier less than the standard limit is as high as 99.9%.When the consolidation of the foundation soil layer is stable,the probability of the most unfavorable vertical displacement of the middle pier is 1~1.8 mm.In this paper,the time-varying and discreteness of the mechanical parameters of the soil layer are considered,and the displacement and reliable probability of the existing high-speed railway bridge pier in the process of soil consolidation are calculated by the time-varying response surface function.It provides a reference for the simplified calculation of the displacement of the existing bridge pier caused by similar new construction projects in the future.

underpass the roadhigh-speed rail bridgesresponse surfacetime-changingsoft soilsreliability

唐冕、卿岑、宋旭明、刘卧

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中南大学 土木工程学院,湖南 长沙 410075

湖南省交通规划勘察设计院有限公司,湖南 长沙 410219

下穿道路 高铁桥梁 响应面 时变 软土 可靠度

2024

铁道科学与工程学报
中南大学 中国铁道学会

铁道科学与工程学报

CSTPCD北大核心EI
影响因子:0.837
ISSN:1672-7029
年,卷(期):2024.21(12)