Influence of Pit-in-Pit Excavation on Double-row Piles in Composite Stratum of Round Gravel and Mudstone

OU Xiao-duo; HUANG Zhong-zheng; JIANG Jie; LUO Fang-zheng; LIANG Ya-hua

doi:10.11988/ckyyb.20200921

PDF(1713 KB)

Journal of Changjiang River Scientific Research Institute ›› 2022, Vol. 39 ›› Issue (1) : 78-85. DOI: 10.11988/ckyyb.20200921

ROCK-SOIL ENGINEERING

Influence of Pit-in-Pit Excavation on Double-row Piles in Composite Stratum of Round Gravel and Mudstone

OU Xiao-duo^1,2,3, HUANG Zhong-zheng¹, JIANG Jie^1,2,3, LUO Fang-zheng⁴, LIANG Ya-hua⁴

Author information +

History +

Abstract

With a deep foundation pit project of Nanning Metro Line 4, we studied the supporting characteristics of double-row piles in round gravel mudstone composite stratum in Nanning using ABAQUS finite element software and field monitoring data, and concluded that double-row piles are well applicable in the round gravel mudstone composite stratum. We further investigated into the influence of pit-in-pit excavation on double-row piles under the conditions of different soil strength weakening percentages and the variations of pit toe coefficient and depth ratio around thresholds. Our findings suggest that the weakening of soil strength has the greatest influence on the supporting effect of double-row piles, followed by pit toe coefficient and depth ratio in sequence. Meanwhile, we propose to take whether the maximum increase percentage of lateral displacement of double-row piles exceeds 20% as the criterion to assess the influence degree of inner pit excavation on the safety and stability of foundation pit. In addition, by analyzing the failure modes and causes of the foundation pit under corresponding working conditions of each parameter, we gave corresponding countermeasures.

Key words

double-row piles / pit-in-pit / round gravel-mudstone mixed strata / numerical simulation / safety factor

Cite this article

EndNote

Ris (Procite)

Bibtex

Download Citations

OU Xiao-duo, HUANG Zhong-zheng, JIANG Jie, LUO Fang-zheng, LIANG Ya-hua. Influence of Pit-in-Pit Excavation on Double-row Piles in Composite Stratum of Round Gravel and Mudstone[J]. Journal of Changjiang River Scientific Research Institute. 2022, 39(1): 78-85 https://doi.org/10.11988/ckyyb.20200921

References

[1] 张油军. 南宁市轨道交通一号线沿线岩层组合模型及区划研究[D]. 南宁:广西大学,2012.
[2] 马福荣,张信贵,易念平. 取样卸荷对膨胀性泥岩强度与变形特性影响的试验研究[J]. 水利水运工程学报,2017,(5):109-116.
[3] 黄钟晖,杨磊. 圆砾层地区基坑围护选型及稳定性分项系数统计分析[J]. 工程地质学报,2013,21(3):438-442.
[4] 徐意智, 廖少明,周小华,等. 上海软土坑中坑型基坑围护的等效深度计算法[J]. 岩土力学,2012,33(9):2736-2742.
[5] SUN Y, ZHOU S, LUO Z. Basal-heave Analysis of Pit-in-Pit Braced Excavations in Soft Clays[J]. Computers & Geotechnics, 2017, 81: 294-306.
[6] 丰土根,熊中华,余波. 坑中坑开挖对悬臂式支护结构侧移的影响分析[J]. 岩土工程学报,2013,35(11):2053-2059.
[7] 江杰,胡何,冯野,等. 坑中坑土体加固对悬臂式支护结构的影响分析[J]. 长江科学院院报,2017,34(3):58-62,66.
[8] 侯新宇,薛必芳,蔺彦玲. 坑趾系数对粉土坑中坑支护结构内力的影响分析[J]. 公路,2017,62(10):273-278.
[9] 孙玉永,肖红菊. 软土地区坑中坑的抗隆起稳定性分析[J]. 中国铁道科学,2013,34(6):66-72.
[10] TAN Y, LU Y, XU C, et al. Investigation on Performance of a Large Circular Pit-in-Pit Excavation in Clay-Gravel-Cobble Mixed Strata[J]. Tunnelling and Underground Space Technology, 2018, 79: 356-374.
[11] 苏华,郝勇. 被动区花岗岩残积土弱化对深基坑的影响[J]. 长江科学院院报,2019,36(11):120-124,131.
[12] PECK R B. Deep Excavation and Tunneling in Soft Ground[C]//Proceedings of the 7th International Conference on Soil Mechanics and Foundation Enginnering, State-of-the-Art Volume, Mexico City,1969: 225-290.
[13] 张虎元,李秀祥. 黄土基坑双排桩支护结构的有限元分析[J]. 地下空间与工程学报,2016,12(4):1102-1109.
[14] 董妍. 软土深基坑双排桩支护结构的变形性状分析[J]. 建筑结构,2017,47(23):86-91.
[15] 申明亮,廖少明,周小华,等. 坑中坑基坑应力场的参数化分析[J]. 岩土工程学报,2010,32(增刊2):187-191.
[16] 任望东,张同兴,张大明,等. 深基坑多级支护破坏模式及稳定性参数分析[J]. 岩土工程学报,2013,35(增刊2):919-92.