摩擦式桩承箱式路基结构长期动力特性模型试验研究  

Model Test of Long-Term Dynamic Characteristics of Friction Pile-Bearing Box-Type Subgrade Structure

作　　者：余雷 王呈金 王祥[3] YU Lei;WANG Chengjin;WANG Xiang(China Railway Economic and Planning Research Institute,Beijing 100038,China;School of Civil Engineering,Southwest Jiaotong University,Chengdu 610031,China;China Railway Siyuan Survey and Design Group Co.,Ltd.,Wuhan 430063,China)

机构地区：[1]中国铁路经济规划研究院有限公司,北京100038 [2]西南交通大学土木工程学院,成都610031 [3]中铁第四勘察设计院集团有限公司,武汉430063

出　　处：《铁道标准设计》2024年第12期1-7,共7页Railway Standard Design

基　　金：中国铁路总公司科技研究开发计划课题(2017G008-C)。

摘　　要：为了研究桩承箱式路基结构长期动力响应特性,设计一种摩擦式桩承箱式路基相似试验模型,进行低周频循环加载试验研究,分析列车双线长期加载工况下,箱式路基结构累积沉降、动位移、振动加速度、动应力沿路基深度和路基横向以及桩间土压力分布规律。研究发现:箱式路基各项动力响应指标前期随着加载次数增加而增大,加载次数在大约10万次以后基本稳定;箱式路基顶面跨中累积沉降稳定在4.32 mm,边侧累积沉降稳定在3.72 mm;箱式路基竖向动位移在箱式路基腹板中空区域衰减较快,且在路基顶板横向上由中间向两侧递减,最大动位移为1.63 mm,但在底板上分布均匀,说明箱式路基整体性较好;箱式路基结构对振动加速度衰减效果显著,跨中加速度从顶板到底板衰减率达到37.8%,加速度在路基顶板横向上腹板交接位置“锐减”,最大加速度为0.38 m/s^(2),而在底板上分布起伏不大。箱式路基动应力沿深度和横向的分布表现为在腹板与顶板交接处存在一定的应力集中现象,应力峰值为142.78 kPa,在设计和施工时应给予重视。箱式路基地基桩间土在疲劳荷载作用下,桩中部土压力稳定在5 kPa左右,桩底部土压力稳定在25 kPa左右,在同一高度截面上,桩间土压力相差不大,分布较为均衡,说明摩擦桩传力效果较好。To investigate the long-term dynamic response characteristics of pile-bearing box-type subgrade structure,a similar test model of friction pile-bearing box-type subgrade was designed,and low frequency cyclic loading tests were conducted.The study analyzed the distribution patterns of cumulative settlement,dynamic displacement,vibration acceleration,dynamic stress along the depth and transverse direction of the subgrade,and soil pressure between piles under long-term loading conditions of a double-track railway.The results showed that all dynamic response indicators of the box-type subgrade initially increased with loading cycles,and stabilized after approximately 100000 cycles.The cumulative settlement at the mid-span of the top surface of the box-type subgrade stabilized at 4.32 mm,while the settlement at the sides stabilized at 3.72 mm.The vertical dynamic displacement in the hollow area of the box-type subgrade web decayed rapidly,and the displacement across the transverse direction of the subgrade top plate decreased from the middle to the sides,with a maximum dynamic displacement of 1.63 mm.However,it remained evenly distributed at the base,indicating good overall integrity of the box-type subgrade.The box-type subgrade structure effectively attenuated vibration acceleration,with the acceleration at the mid-span attenuating by 37.8%from the top to the bottom plate.A“sharp drop”in acceleration was observed at the web joint area on the top plate,with maximum acceleration reaching 0.38 m/s^(2),while the variation on the bottom plate was minimal.The distribution of dynamic stress along the depth and transverse direction showed stress concentration at the intersection between the web and top plate,with a peak stress of 142.78 kPa,which should be carefully considered in design and construction.Under fatigue loading,the soil pressure between the foundation piles stabilized at approximately 5 kPa at the middle of the pile and 25 kPa at the bottom,with minimal pressure variation at the same cross-sectional height

关 键 词：铁路路基 长期动力特性 模型试验 箱式路基结构 摩擦式桩承 动力响应分布 

分 类 号：U213.1[交通运输工程—道路与铁道工程] TU473.1[建筑科学—结构工程]