Excavation deformation of deep foundationpit of subway station in coastal marsh area

Abstract

Abstract: There are not many deep foundation pits in long and narrow subway stations in coastal marsh area, which are difficult to excavate due to the effect of upper silt soil and rich underground water. The deep foundation pit excavation of the subway station under this condition in the Qingdao area is selected for real-time monitoring, and a three-dimensional numerical model is established by using Midas GTS NX software for analysis. The analysis shows that the deep horizontal displacement-depth deformation curve of the pile is in the shape of a bow, and the maximum horizontal displacement of retaining pile appears at 0.55H(H is the excavation depth of foundation pit). The surface settlement around the foundation pit is a parabola with a small settlement, and the maximum settlement is about 0.058%H, which is 0.6H away from the foundation pit. There is a relationship between the maximum horizontal displacement δ_hmax of the retaining wall and the maximum settlement δ_vmax of the surface, which is δ_vmax=0.88 δ_hmax. In addition, compared with the deep foundation pit engineering under the working conditions in other areas, the excavation deformation of the water-rich deep foundation pit in the marsh area shows a similar change law.

Key words: coastal marsh area, long and narrow deep foundation pit, monitoring, numerical simulation

CLC Number:

TU473.2

REN Xiao-min, LIU Jun-jie, LIU Jun-wei, WANG Chen. Excavation deformation of deep foundationpit of subway station in coastal marsh area[J]. Journal of Lanzhou University of Technology, 2023, 49(2): 138-143.

References

[1] 杨有海,王建军,武进广,等.杭州地铁秋涛路车站深基坑信息化施工监测分析 [J].岩土工程学报,2008(10):1550-1554.
[2] 霍润科,颜明圆,宋战平.地铁车站深基坑开挖监测与数值分析 [J].铁道工程学报,2011,28(5):81-85.
[3] 张艳书,薛栩超,庄海洋,等.软土层对地铁狭长深基坑地表沉降的影响研究 [J].地下空间与工程学报,2018,14(6):1639-1651.
[4] CLOUGH G W,O’ROURKE T D.Construction induced movements of in situ walls [C]//Proc ASCE Conference on Design and Performance of Earth Retaining Structures.New York:[s.n.],1990:439-470.
[5] FINNO R J,ROBOSKI J F.Three-dimensional responses of a tied-back excavation through clay [J].Journal of Geotechnical and Geoenvironmental Engineering,2006,132(10):1370.
[6] GOH A T C,ZHANG R H,WANG W,et al.Numerical study of the effects of groundwater drawdown on ground settlement for excavation in residual soils [J].Acta Geotechnica,2020,15:1259-1272.
[7] 丁智,王达,虞兴福,等.杭州地铁新塘路、景芳路交叉口工程深基坑监测分析 [J].岩土工程学报,2013,35(S2):445-451.
[8] 朱建才,朱亦弘,王旭,等.杭州某软土超深基坑变形性状研究 [J].地下空间与工程学报,2018,14(S1):335-341.
[9] 应宏伟,王奎华,谢康,等.杭州解百商业城半逆作法深基坑支护设计与监测 [J].岩土工程学报,2001(1):79-83.
[10] LIU G B,NG C W W,WANG Z W.Observed performance of a deep multistrutted excavation in Shanghai soft clays [J].Journal of Geotechnical and Geoenvironmental Engineering,ASCE,2005,131(8):1004-1013.
[11] 王卫东,徐中华,王建华.上海地区深基坑周边地表变形性状实测统计分析 [J].岩土工程学报,2011,33(11):1659-1666.
[12] MANA A I,CLOUGH G W.Prediction of movements for braced cuts in clay [J].Journal of Geotechnical Engineering Division,ASCE,1981,107(6):759-777.
[13] ZHANG W G,HOU Z J,GOH A T C,et al.Estimation of strut forces for braced excavation in granular soils from numerical analysis and case histories [J].Computers and Geotechnics,2019,106:286-295.
[14] ZHANG W G,GOH A T C,XUAN F.A simple prediction model for wall deflection caused by braced excavation in clays [J].Computers and Geotechnics,2015,63:67-72.
[15] ZHANG W G,GOH A T C,GOH K H,et al.Performance of braced excavation in residual soil with groundwater drawdown [J].Underground Space,2018,3:150-165.