竖向荷载对黏土地基中单桩水平受荷性能的影响  

Effect of vertical load on lateral behavior of single pile in clay

作　　者：何奔[1,2] 王欢[1] 洪义[1] 王立忠[1] 赵长军 秦肖 

机构地区：[1]浙江大学土木工程学系,浙江杭州310027 [2]中国电建集团华东勘测设计研究院有限公司,浙江杭州311122 [3]浙江省交通规划设计研究院,浙江杭州310002 [4]温州市交通投资集团有限公司,浙江温州325000

出　　处：《浙江大学学报（工学版）》2016年第7期1221-1229,共9页Journal of Zhejiang University：Engineering Science

基　　金：国家杰出青年科学基金资助项目(51325901);国际科技合作计划资助项目(2015DFE72830);国家自然科学基金资助项目(51338009);中央高校基本科研业务费专项资金资助项目(2016QN4022)

摘　　要：为了研究正常固结土(NC)和超固结土(OC)中,竖向荷载作用后,允许土体固结和超静孔压消散的条件下,桩体的水平静、循环受荷性能,开展8组离心模型试验.基于试验结果,开展三维有限元模拟(FEA),揭示竖向荷载对桩体水平受荷性能的影响机理,分析不同竖向荷载作用下,桩体水平初始刚度和极限承载力的变化规律.结果表明,在正常固结土中,施加竖向工作荷载,并允许土体孔压消散,减少了土体的初始应力比,增加了可发挥的土体不排水抗剪强度,提高10%的桩基水平极限承载力和50%的初始桩头刚度;在超固结土中,施加竖向荷载,增加了土体的初始应力比,减少了可发挥的土体不排水抗剪强度,降低了13%桩基的水平静极限承载力和33%的初始桩头刚度.A series of detailed centrifuge test were performed in order to investigate the lateral monotonicand cyclic behavior of a single pile in normal （NC） and over consolidated clay （OC） with and without applicationof vertical loading at the pile head. Three-dimensional finite element analyses （F E A ） were conductedto offer further insights into the effects of vertical loading on the lateral initial stiffness and bearing capacityof the pile. Both physical and numerical investigation reveal that after applying the vertical load andallowing the dissipation of excess pore pressure in N C , the stress ratio of the soil around the pile decreaseswhile the mobilisable undrained shear stength increases, resulting in 1 0 % and 5 0 % increase of the lateralinitial stiffness and bearing capacity of the pile, respectively. Due to application of vertical load to a singlepile in the over consolidated clay, the soil stress ratio prior to lateral loading increases while the mobilisableundrained shear stength decreases, consequently leading to 1 3 % and 3 3 % reduction of the lateral initialstiffness and bearing capacity of the pile, respectively.

关 键 词：竖向荷载 单桩 水平受荷性能 黏土 离心机试验 有限元模拟 极限承载力 初始刚度 

分 类 号：TU473[建筑科学—结构工程]