考虑非对称冻结的塔杆基础模型实验研究  

Model test study on tower foundation considering asymmetric freezing

作　　者：熊维林 葛洪林[2] 富海鹰[1] XIONG Weilin;GE Honglin;FU Haiying(School of Civil Engineering,Southwest Jiaotong University,Chengdu 610031,China;China Railway Second Institute Engineering Group Co.,Ltd.,Chengdu 610031,China)

机构地区：[1]西南交通大学土木工程学院,四川成都610031 [2]中铁二院工程集团有限责任公司,四川成都610031

出　　处：《铁道科学与工程学报》2022年第4期931-940,共10页Journal of Railway Science and Engineering

基　　金：国家自然科学基金青年科学基金资助项目(42077236);四川省科技资助计划(2021YFH0037)。

摘　　要：多年冻土区的地基土经常受冻胀的影响,但由于斜坡或边坡的存在,塔杆不仅存在拔起还同时存在侧向偏移现象,其病害机理倾向复杂化。为研究多年冻土区临坡塔杆桩基位移变化以及桩周路基土的温度规律,基于模型实验,研究路基在持续非对称冻结情况下塔杆桩基周围的温度场分布以及桩位移变化规律,并发明和试验一种非对称扩底锥形桩。研究结果表明:分阶段加载温度条件下,土体温度呈阶梯型下降,且初始变化规律异于后续加载阶段的变化规律,桩周温度场分布非均匀。初始试验阶段冻拔量以及侧向位移随时间稳定增长,后续加载阶段表现出位移曲线平台,且初始阶段量值最大。第1和第2温度加载阶段完成后新型桩的抗拔以及抵抗侧向偏移的效果显著,当温度加载条件下降至−20℃,抗侧向位移能力减弱,抗拔效果仍显著。针对多年冻土区的临坡塔杆桩基应避免路基遭受持续非均匀冻结作用的情况,在施工以及投入使用后期应随着环境温度变化采取足够的保温措施,并且设计时可对桩基设置适当的抗拔以及抗侧向偏移措施,以减弱非均匀冻结对桩基产生的法向以及切向的叠加作用效果。In permafrost regions,the foundation soil is often affected by frost heaving.However,due to the existence of slopes or side slopes,the tower poles are not only pulled up but also laterally shifted,and its distress mechanism tends to be complicated.In order to study the position change of tower pole pile foundation and the temperature law of subgrade soil around the pile in permafrost region,based on the model experiment,this paper studied the temperature field distribution around tower pole pile foundation and the change law of pile displacement under the condition of continuous asymmetric freezing of subgrade,and invented and tested an asymmetric belled cone pile.The results show that under the condition of staged loading temperature,the soil temperature decreases in a stepwise manner,and the initial variation law is different from that of subsequent loading stages.The temperature field around the pile is unevenly distributed.The frozen pullout amount and lateral displacement increase steadily with time in the initial test stage,and the displacement curve platform appears in the subsequent loading stage,with the largest value in the initial stage.After the completion of the first and second temperature loading stages,the uplift and lateral displacement resistances of the new pile are remarkable.When the temperature loading condition drops to-20℃,the lateral displacement resistance decreases,and the uplift resistance is still remarkable.Finally,it is concluded that in actual construction,the tower pole pile foundation facing the slope in permafrost regions should avoid the subgrade from sustained uneven freezing,and adequate heat preservation measures should be taken with the change of environmental temperature in the later stage of construction and service,and appropriate anti-uplift and anti-lateral deviation measures can be set for the pile foundation in design to reduce the superposition effect of uneven freezing on the pile foundation in normal and tangential directions.

关 键 词：铁路路基 冻拔 侧向位移 非对称冻结 塔杆基础 

分 类 号：TU445[建筑科学—岩土工程]