扩底桩竖向承载特性及群桩效应研究  

Study on Vertical Bearing Characteristics and Group Pile Effect of Expanded⁃base Piles

作　　者：邓友生[1,2] 吴阿龙 陈茁 庄子颖 肇慧玲 董晨辉 DENG Yousheng;WU Along;CHEN Zhuo;ZHUANG Ziying;ZHAO Huiling;DONG Chenhui(School of Architecture and Civil Engineering,Xi’an University of Science and Technology,Xi’an 710054,China;Key Laboratory of Rail Transit Engineering Safety and Intelligent Control,Xi’an Traffic Engineering Institute,Xi’an 710300,China;Plie-supported Structures Research&Test Center,Xi’an University of Science and Technology,Xi’an 710054,China)

机构地区：[1]西安科技大学建筑与土木工程学院,西安710054 [2]西安交通工程学院轨道交通工程安全与智能控制重点实验室,西安710300 [3]西安科技大学桩承结构研究中心,西安710054

出　　处：《铁道建筑》2024年第2期107-111,共5页Railway Engineering

基　　金：国家自然科学基金(51878554);陕西省自然科学基础研究计划(2018JZ5012)。

摘　　要：为探明扩底群桩竖向承载特性,采用扩底桩筏结构,开展单桩(扩径比分别为1.5、2.0、2.5、3.0)和桩筏(扩径比为2)基础静载模型试验,分析其荷载传递规律,并建立桩间距为3.75、4.00、4.50、5.00倍桩直径时扩底桩筏基础有限元模型,研究桩间距对群桩效应影响。结果表明:扩底单桩和扩底桩筏结构荷载沉降曲线均为缓变型;扩底桩极限承载力随扩径比增大而逐渐增大,扩径比2.5~3.0时极限承载力增幅变缓,建议扩底桩扩径比取2.5~3.0;由于桩土共同沉降,桩间土压缩,桩土作用更充分,扩底桩筏基础中心桩侧摩阻力荷载分担比比扩底单桩增大了17.71%;群桩效应系数随桩间距增大而逐渐增大,桩间距为4.5~5.0倍桩直径时群桩效应系数增幅较小,群桩效应较弱,建议扩底桩筏基础桩间距取值不小于4.5倍桩直径。To investigate the vertical bearing characteristics of pile groups with expanded-base,static load model tests were conducted on single pile foundations with expanded diameter ratios of 1.5,2.0,2.5,and 3.0,as well as pile raft foundations with expanded diameter ratios of 2,using an expanded-base pile raft structure.Analyzed the load transfer law and established a finite element model for the expanded-base pile raft foundation with pile spacing of 3.75,4.00,4.50,and 5.00 times the pile diameter,and studied the influence of pile spacing on the group pile effect.The results show that the load settlement curves of single pile and raft structures with expanded-base are both of a slowly changing type.The ultimate bearing capacity of the expanded-base pile gradually increases with the increase of the expansion ratio.When the expansion ratio is 2.5~3.0,the increase in the ultimate bearing capacity slows down.It is recommended to take the expansion ratio of the expanded-base pile as 2.5~3.0.Due to the joint settlement of piles and soil,the soil between piles is compressed,and the pile-soil interaction is more sufficient.The load sharing ratio of the center pile side frictional resistance of the expanded-base pile raft foundation is increased by 17.71%compared to that of a single expanded-base pile.The coefficient of pile group effect gradually increases with the increase of pile spacing.When the pile spacing is 4.5~5.0 times the pile diameter,the increase in the coefficient of pile group effect is relatively small,and the effect of pile group is weak.It is recommended that the pile spacing of the expanded-base pile raft foundation be not less than 4.5 times the pile diameter.

关 键 词：扩底桩筏结构 模型试验 承载特性 群桩效应 扩径比 桩间距 

分 类 号：TU473.1[建筑科学—结构工程]