摘要
锁口钢管桩具有施工效率高、可回收重复利用等优点,逐渐被用于基坑围护结构中。为探明锁口钢管桩在基坑支护中的受力和变形特点,开展锁口钢管桩围护悬臂基坑开挖相似模型试验。为模拟锁口管桩的结构特点,创新性地采用3D打印技术,以Somos®Taurus材料作为打印基质材料,制作带锁口接头的模型试验桩。模型试验在砂土中进行,采用砂雨法填筑土体,通过人工开挖模拟基坑开挖至围护结构变形失效的全过程。试验过程中对桩顶水平位移、桩身应变和土体表面的沉降进行实时测量,桩身水平位移分布通过桩身应变反算得到。研究表明:采用3D打印技术能快速、精细地制作锁口钢管桩模型,满足模型试验的要求;地表沉降及围护结构变形随着开挖深度增加而增大,桩身呈现出分布荷载下悬臂梁的变形特点;从基坑开挖浅部至围护结构失效,桩身正弯矩及桩顶的水平位移呈非线性增长,但最大正弯矩点始终位于开挖面以下30~35 cm的深度范围;锁口钢管桩作为围护结构具有较好的整体性,在围护结构失效后桩身没有发生剪切破坏;在无内支撑条件下,钢管桩围护结构为柔性围护结构,其结构安全合理的插入比λ在1.8~2.5范围,其值大于其他刚性围护结构。
Locking steel pipe pile has advantages of quick construction efficiency and recycle utilization.Nowadays,it is widely used as a retaining structure in excavation engineering.Non-inner supported excavation with locking steel pipe pile retaining structure similar model test was carried out to investigate the deformation characteristics of locking steel pipe pile.To simulate the structural characteristics of locking steel pipe pile,three dimensional(3D)printing technology was creatively applied to manufacture locking steel pipe pile by using Somos®Taurus as printing base material.The similar excavation model test with locking steel pipe pile retaining structure was conducted in dry sand and the soils were filled using rain fall method.The excavation from initial state to retaining structure failure was simulated by manual excavation.The lateral displacement at the pile top,ground surface settlements and the bending moment of the piles were continuously measured during the whole process of excavation.The lateral deflection of model pile was back-analyzed using pile shaft strains.The testing results shown that the 3D printing technology can rapidly and accurately manufacture locking steel pipe model piles,which meet the model test requirement perfectly.The deformation of locking steel pipe pile and the ground surface settlement increased with excavation depth,the deflection of model pile was similar as cantilever beam subjected to distributed load.When excavation depth varies from shallow depth to structure failure,both of positive bending moment in model pile and the lateral displacement in pile top increased nonlinearly.However,the positions of maximum positive bending moment maintain range from 30–35 cm below the excavation face.As a retaining structure,the locking steel pipe piles possess a good integrality.The shear failure did not occur in the pile shaft when the retaining structure reached failure state.In non-inner supported retaining structure,the locking steel pipe pile was flexible structure and its safe installation ratio was suggested from 1.8 to 2.5,which was greater than the other rigid retaining structures.
作者
韦实
邓成龙
梁荣柱
王新新
吴小建
孙廉威
WEI Shi;DENG Chenglong;LIANG Rongzhu;WANG Xinxin;WU Xiaojian;SUN Lianwei(Faculty of Engineering,China University of Geosciences,Wuhan,Hubei 430074,China;College of Civil Engineering and Architecture,Guangxi University,Nanning,Guangxi 530004,China;Shanghai Construction Group Co.,Ltd.,Shanghai 200080,China)
出处
《岩石力学与工程学报》
EI
CAS
CSCD
北大核心
2020年第S02期3676-3686,共11页
Chinese Journal of Rock Mechanics and Engineering
基金
国家自然科学基金资助项目(41807262)
湖北省自然科学基金资助项目(2018CFB179)
上海市青年科技英才扬帆计划(19YF1421000)。
关键词
基坑工程
锁口钢管桩
3D打印
模型试验
围护结构
excavation engineering
locking steel pipe pile
3D printing technology
model tests
retaining structure
