摘要
锁口钢管桩通过桩身锁口接头相互连接可形成排桩式围护结构,在软土地区基坑工程中应用广泛。为探明悬臂式与内支撑式锁口钢管桩围护结构的受力变形特点及差异,分别开展了锁口钢管桩悬臂式和内支撑式围护基坑开挖相似模型试验,并采用3D打印技术制作带锁口接头的模型试验桩。试验过程中对桩顶水平位移、桩身应变和土体表面沉降进行实时监测与分析。试验结果表明:(1)通过3D打印制作锁口钢管桩模型具有精度高、速度快等优点,能极大地反映锁口钢管桩的接头特点;(2)对于锁口钢管桩悬臂式围护结构,从基坑开挖至围护结构失效前,土体沉降由凹槽型分布逐渐变为三角形分布,桩身弯矩反弯点出现在开挖面附近,并随开挖深度增加而下移,地表沉降极值与桩身水平位移极值之比(δvm/δhm)约为1,当围护结构失效后,反弯点位置几乎不再变化,地表最大沉降与桩身最大侧移之比(δvm/δhm)逐渐减小,在0.5~0.75之间;对于锁口钢管桩内支撑式围护结构,在相同开挖深度下,土体沉降呈凹槽型分布,桩身弯矩反弯点始终在开挖面处,地表最大沉降与桩身最大侧移之比(δvm/δhm)逐渐从0.5增大至1。
Locked steel pipe(LSP)piles can form a row-pile enclosure structure by interconnecting the lock joints,and have been widely used in foundation pit projects in soft soil areas.To investigate the stress and deformation characteristics and differences between cantilevered and internally-braced LSP pile enclosure structures,this paper carries out similar model tests of the pit excavations of both cantilevered and internally-braced LSP pile enclosures respectively,and uses 3D printing technology to produce the piles with locked joints for the model tests.During the test,real-time monitoring and analysis were conducted for pile-top horizontal displacement,pile strain and soil surface settlement.The test results show that:(1)The LSP pile model made through 3D printing has the advantages of high precision and fast speed,implying that it can greatly reflect the joint characteristics of LSP piles;and(2)For the cantilevered enclosure structure with LSP piles,from the excavation of the foundation pit to the failure of the enclosure structure,the soil settlement distribution gradually shifts from a notch-type distribution to a triangle distribution,with the reverse-bending point of the pile moment appearing near the excavation surface and drops with the increase of the excavation depth.The ratio of the extreme value of the surface settlement to the extreme value of the horizontal displacement of the piles(δvm/δhm)is approximately 1,but when the enclosure structure loses its effectiveness,the position of the reverse-bending point almost has no change,while the ratio of the maximum settlement of the ground surface to the maximum lateral displacement of the piles(δvm/δhm)gradually decreases between the range of 0.5 and 0.75.For the internally-braced enclosure structure with LSP piles,under the same excavation depth,the soil settlement distribution is in a groove-type distribution,with the reverse-bending point of the pile moment remaining on the excavation surface the whole time,and the ratio of the maximum surface settlemen
作者
梁荣柱
韦实
王新新
孙廉威
吴小建
LIANG Rongzhu;WEI Shi;WANG Xinxin;SUN Lianwei;WU Xiaojian(School of Engineering(Wuhan),China University of Geosciences,Wuhan 430074;School of Civil Engineering and Architecture,Guangxi University,Nanning 530004;Shanghai Construction Group Co.,Ltd.,Shanghai 200080)
出处
《现代隧道技术》
CSCD
北大核心
2022年第3期172-182,共11页
Modern Tunnelling Technology
基金
国家自然科学基金(41807262)
上海市青年科技英才扬帆计划(19YF1421000).
关键词
基坑工程
围护结构
锁口钢管桩
3D打印技术
模型试验
Foundation pit works
Enclosure structure
Locked steel pipe(LSP)piles
3D printing technology
Model test
