深基坑双排微型桩-锚-撑组合支护结构受力与变形特性  

Force and deformation characteristics of double-row miniature pile−anchor−support combination support structure for deep foundation pit

作　　者：闫楠[1] 郝增明 白晓宇[1] 张立 孙林娜[1] 张启军 YAN Nan;HAO Zengming;BAI Xiaoyu;ZHANG Li;SUN Linna;ZHANG Qijun(School of Civil Engineering,Qingdao University of Technology,Qingdao 266520,China;Qingdao Yegao Construction Engineering Co.Ltd.,Qingdao 266022,China)

机构地区：[1]青岛理工大学土木工程学院,山东青岛266520 [2]青岛业高建设工程有限公司,山东青岛266022

出　　处：《中南大学学报（自然科学版）》2024年第6期2295-2309,共15页Journal of Central South University:Science and Technology

基　　金：国家自然科学基金资助项目(51778312,51708316);山东省自然科学基金重点项目(ZR2020KE009);山东省博士后创新项目(201903043)。

摘　　要：为深入研究深厚杂填土地层深基坑微型桩-锚-撑组合支护结构随基坑开挖的受力与变形演化规律,首先,依托青岛市某深基坑工程开展双排微型桩-锚-撑原位试验,分析开挖工况下前、后排桩的桩身弯矩分布规律;然后,结合ABAQUS有限元模拟方法,明确微型桩、预应力锚索与钢支撑之间的协同作用及基坑变形规律;最后,揭示微型桩桩径变化、支护结构作用对桩身受力及基坑变形的影响机制。研究结果表明:增加开挖深度引起桩身正弯矩和负弯矩不断增大,极值点位置不断下移,桩身弯矩整体呈正“S”形分布;开挖至基底,前排桩的桩身反弯点分别位于钢支撑下方0.5 m和开挖面位置,后排桩的桩身反弯点分别位于钢支撑下方0.5 m和开挖面下方1.0 m范围内;基坑开挖竖向影响范围约为1.35H(H为基坑开挖深度),桩径增加近1倍,土体水平位移仅减少约51%,且随桩径继续增加,其对于限制基坑变形效果不显著;相较于桩锚支护结构,桩-锚-撑支护结构作用下,前、后排桩的最大水平位移分别减小34.9%和27.3%,基坑土体的最大水平位移减小46.0%。In order to study the evolution of force and deformation of miniature pile-anchor-support structure with excavation of deep miscellaneous soil,firstly,in-situ test of double-row miniature pile-anchor-support was conducted based on a deep foundation pit project in Qingdao to analyze the distribution of pile moment of front and rear piles under excavation conditions.Secondly,combined with ABAQUS finite element simulation method,the synergy effects between miniature pile,prestressed anchor cable and steel support and the deformation of foundation pit were clarified.Finally,the influence mechanism of miniature pile diameter change and support structures on pile force and foundation pit deformation were revealed.The results show that the increase of excavation depth causes the pile positive and negative bending moment to increase continuously,the extreme point position shifts downward,and the overall pile bending moment is a positive"S"shape distribution.Excavation to the bottom,the pile reverse bending points of the front row of piles are located 0.5 m below the steel support and the location of the excavation surface,and the pile reverse bending points of the back row of piles are located 0.5 m below the steel support and within 1.0 m below the excavation surface.The vertical influence range of foundation pit excavation is about 1.35H(H is the depth of foundation pit excavation).The pile diameter is nearly doubled,but the soil horizontal displacement only decreases by about 51%,and it is not significant to limit the deformation of the foundation pit with the pile diameter continuing to increase.Compared to the pile-anchor support structure,under the action of pile-anchor-support structure,the maximum horizontal displacement of the front and rear row piles decreases by 34.9%and 27.3%,respectively,and the maximum horizontal displacement of the excavation soil decreases by 46.0%.

关 键 词：深基坑 微型桩 锚索 钢支撑 原位试验 有限元模拟 

分 类 号：TU473[建筑科学—结构工程]