盐湖区高速铁路长短桩复合地基变形特性  

Deformation characteristics of long-short pile composite foundation for high-speed railway in salt lake region

作　　者：杨晓华[1] 王东清 张莎莎[1] 孔祥鑫 李安洪[2] 赵彦虎 YANG Xiao-hua;WANG Dong-qing;ZHANG Sha-sha;KONG Xiang-xin;LI An-hong;ZHAO Yan-hu(School of Highway,Chang'an University,Xi'an 710064,Shaanxi,China;China Railway Eryuan Engineering Group Co.,Ltd.,Chengdu 610031,Sichuan,China)

机构地区：[1]长安大学公路学院,陕西西安710064 [2]中铁二院工程集团有限责任公司,四川成都610031

出　　处：《交通运输工程学报》2024年第3期181-192,共12页Journal of Traffic and Transportation Engineering

基　　金：国家自然科学基金项目(42101126);陕西省自然科学基础研究计划(2019JM-147);中国中铁股份有限公司科技研究开发计划(2017-重大-11-04)。

摘　　要：依托伊朗德黑兰至伊斯法罕高速铁路项目,开展全长桩(混凝土桩)、全短桩(碎石桩)和长短桩(混凝土桩-碎石桩)复合地基离心模型试验,模拟了填筑与工后2年的地基沉降过程,研究了桩长比、桩间距、短桩布置形式与填土高度对地基沉降特性的影响。研究结果表明:在相同地质条件下,全长桩、长短桩和全短桩复合地基的桩间土工后沉降分别为28.16、36.17和53.95 mm,分别减小了70%、60%和40%以上,因此,全长桩和长短桩复合地基工后沉降可以满足规范要求(不超过于50 mm),长短桩复合地基工后沉降介于全长桩和全短桩复合地基工后沉降之间;桩长比每增加0.1,桩间距分别为3、4倍桩径时长短桩复合地基沉降分别减小7%~12%和8%左右,表明提高桩长比能够显著改善复合地基的沉降控制效果,并随桩间距的增大而更为有效;桩间距从3倍桩径增大到5倍桩径,桩长比为0.5时复合地基沉降从36.56 mm增至55.71 mm,桩长比为0.7时复合地基沉降从28.38 mm增至45.93 mm,表明在较大桩间距下沉降控制效果较差,为使沉降满足规范要求,桩间距为5倍桩径时桩长比应不小于0.5;桩长比为0.7时,一长一短、一长两短和一长三短3种布置形式复合地基沉降分别为28.37、38.06和43.69 mm,表明在相邻两长桩之间布置更多短桩可以兼顾沉降控制与经济性,短桩布置越多,长桩应力越大,但应力整体趋势保持不变;不同填土高度下长短桩复合地基中碎石桩块体以向下运动为主,长桩刺入垫层,短桩刺入软土,并在剪切变形与块体侧向挤出的作用下形成局部潜在滑移面。Based on the Tehran-Isfahan high-speed railway project in Iran,centrifuge model tests were conducted for full-length pile(concrete pile) composite foundation,full-short pile(gravel pile) composite foundation,and long-short pile(concrete pile-gravel pile) composite foundation,their settlement processes were simulated in embankment construction and following two years,and the effects of pile length ratio,pile spacing,short pile layout and filling height on the settlement characteristics were studied.Research results show that under the same geological condition,the post-construction settlements of the soils between piles for full-length,long-short,and full-short pile composite foundations are 28.16,36.17,and 53.95 mm and reduce by over 70%,60%,and 40%.Therefore,the post-construction settlements for full-length and long-short pile composite foundations meet the regulatory requirement of no more than 50 mm,and the post-construction settlement of long-short pile composite foundation is between the settlements of full-length and full-short pile composite foundations.For long-short pile composite foundation,increasing pile length ratio by 0.1 may reduce settlement by 7%-12% for the pile spacing of 3 times pile diameter and around 8% for the pile spacing of 4 times pile diameter,indicating that increasing pile length ratio can significantly improves settlement control,and the control is more effective as pile spacing increases.When the pile spacing increases from 3 times pile diameter to 5 times pile diameter,composite foundation settlement increases from 36.56 mm to 55.71 mm for a pile length ratio of 0.5,and from 28.38 mm to 45.93 mm for a pile length ratio of 0.7,indicating that settlement control is less effective at larger pile spacing.To meet the regulatory settlement requirement,the pile length ratio should not be less than 0.5 when the pile spacing is 5 times pile diameter.For a pile length ratio of 0.7,composite foundations settlements with one long-one short,one long-two short,and one long-three short pile arra

关 键 词：高速铁路 路基工程 长短桩复合地基 软弱盐渍土 沉降 离心模型试验 数值模拟 

分 类 号：U213.15[交通运输工程—道路与铁道工程]