摘要
花管土钉已被广泛应用于基坑工程中,但其抗拔承载机理尚不明确。根据花管土钉的支护原理,分析其三种破坏形式,提出花管土钉的四个受力阶段;基于库仑土压力理论,将滑动土体上方看作均布荷载,推导出花管土钉极限抗拔承载力的计算公式;结合兰州某基坑实例,将《建筑基坑支护技术规程》中的花管土钉极限抗拔承载力计算方法与本文计算方法进行拉拔试验,并对结果进行对比分析。研究表明:花管土钉的破坏模式主要为花管杆体被拉断、出浆锚固体被剪断及出浆锚固体前端土体变形过大;花管土钉的四个受力阶段包括静止阶段、塑性区产生阶段、塑性区扩张阶段和破坏阶段;在花管土钉极限抗拔承载力的组成中,出浆锚固体提供的抗拔力所占比重随花管埋深的增大而显著增大,是花管土钉极限抗拔承载力的重要组成部分。
Soil nails of steel tubes have been widely used in foundation pit engineering,but their mechanism of uplift bearing capacity remains unclear.According to its supporting principle,three failure modes and four loading stages of soil nails of steel tubes were analyzed.Based on the Coulomb earth pressure theory,a calculation formula for the uplift bearing capacity of the soil nail of a steel tube was derived by taking the gravity of the soil above the sliding soil as uniformly distributed loads.By taking a foundation pit in Lanzhou as an example,the calculation method for the ultimate uplift bearing capacity of soil nail of steel tube introduced in the Technical Specification for Retaining and Protection of Building Excavations was proposed in this paper,and the results of the uplift test were compared and analyzed.Results show that in the failure mode of the soil nail of the steel tube,the bolt body is pulled off,and the anchor body is cut off.In addition,the deformation of soil in front of the anchor is large.The four stress stages include stationary,plastic zone generation,plastic zone expansion,and failure stages.The proportion of uplift provided by the slurry anchor body increases significantly with an increase in the embedded depth of the steel pipe,which is an important component of the ultimate uplift bearing capacity of the soil nail of a steel tube.
作者
王正振
李明聪
张磊
周勇
叶帅华
马天忠
WANG Zhengzhen;LI Mingcong;ZHANG Lei;ZHOU Yong;YE Shuaihua;MA Tianzhong(School of Civil Engineering,Lanzhou University of Technology,Lanzhou 730050,Gansu,China;Key Laboratory of Disaster Prevention and Mitigation in Civil Engineering of Gansu Province,Lanzhou University of Technology,Lanzhou 730050,Gansu,China;Western Engineering Research Center of Disaster Mitigation in Civil Engineering of Ministry of Education,Lanzhou University of Technology,Lanzhou 730050,Gansu,China)
出处
《地震工程学报》
CSCD
北大核心
2023年第3期681-688,共8页
China Earthquake Engineering Journal
基金
国家自然科学基金(52068048)
甘肃省自然科学基金(21JR11RM052)
甘肃省青年科技基金计划(22JR5RA286)
甘肃省住房和城乡建设厅建设科技项目(JK2022-03)
甘肃省高等学校青年博士基金项目(2022QB-045)。
关键词
土力学
基坑工程
花管土钉
极限抗拔承载力
计算模型
soil mechanics
foundation pit engineering
soil nail of steel tube
ultimate uplift bearing capacity
calculation model
