摘要
多年冻土区钻孔灌注桩基础施工带来的热扰动削弱了桩基础的早期热稳定性,降低了桩基承载力。通过早期热稳定性影响因素、热稳定性对承载力的影响及其改善措施三个方面对钻孔灌注桩基础早期热稳定性的研究现状进行归纳总结。研究表明:首先,多年冻土区钻孔灌注桩基础具有热扰动范围大、回冻时间长的特点,其中水化热及胶凝材料、入模温度、成孔方式作为主动影响因素是热扰动的主要来源,桩基特征及冻土工程地质条件作为间接因素也对早期热稳定性产生次要影响;其次,钻孔灌注桩热扰动显著降低了桩基早期的承载力,延缓了上部结构施工时间;在削弱桩基早期热扰动方面,人工制冷、热管等措施具有良好的加速回冻效果。基于桩基承载力与冻土地温的密切关系,未来还需进一步定量评估冲击钻成孔施工方式、灌注桩施工季节、群桩设计参数对桩基早期热扰动的影响,深入认识早期热扰动作用下桩基承载力的变化规律、设计荷载与冻土蠕变的关系及其对工期的影响,并研发施工更加便利、效果更加显著、适用范围更广的低水化热胶凝材料和钻孔灌注桩控温措施,有效提高钻孔灌注桩早期的承载力。
The thermal disturbance caused by the construction of cast-in-place pile foundation in permafrost regions weakens the early thermal stability of the pile foundation and reduces the bearing capacity.This paper discusses the research of early thermal stability of cast-in-place pile foundation from three aspects:the influencing factors of early thermal stability,the influence of thermal stability on bearing capacity,and the improvement measures.Cast-in-place pile foundations in permafrost regions have the characteristics of large thermal disturbance range and long refreezing time.The heat of hydration and cementitious materials,casting temperature,and drilling methods are the main sources of thermal disturbances.Pile characteristics and geological conditions as indirect factors also have a secondary impact on the early thermal stability.The thermal disturbance significantly reduces the early bearing capacity of the cast-in-place pile foundation and delay the construction time of the superstructure.The cooling liquid and thermosyphons have been verified by actual engineering to have a significant effect of accelerating refreezing process.The future related research is prospected,and it is believed that the thermal disturbance process caused by different drilling methods,the low-hydration thermal cementing materials suitable for permafrost regions,and cost-effective temperature control measures should be further studied to improve early bearing capacity.
作者
侯鑫
杨斌
陈继
赵静毅
芮鹏飞
HOU Xin;YANG Bin;CHEN Ji;ZHAO Jingyi;RUI Pengfei(State Key Laboratory of Frozen Soil Engineering,Northwest Institute of Eco-Environment and Resources,Chinese Academy of Sciences,Lanzhou 730000,China;Beiluhe Observation Station of Frozen Soil Engineering and Environment,Northwest Institute of Eco-Environment and Resources,Chinese Academy of Sciences,Lanzhou 730000,China;University of Chinese Academy of Sciences,Beijing 100049,China;Command Center of Comprehensive Natural Resources Survey,China Geological Survey,Beijing 100055,China)
出处
《冰川冻土》
CSCD
北大核心
2020年第4期1202-1212,共11页
Journal of Glaciology and Geocryology
基金
中国科学院战略性先导科技专项(A类)“泛第三极环境变化与绿色丝绸之路建设”(XDA20020102)
冻土工程国家重点实验室基金项目(SKLFSE-ZT-34)资助
关键词
多年冻土
钻孔灌注桩
热稳定性
承载力
permafrost
cast-in-place pile
thermal stability
bearing capacity
