Undrained stability of pit-in-pit braced excavations under hydraulic uplift

Fengwen Lai, Fuquan Chen, Songyu Liu*, Suraparb Keawsawasvong, Jim Shiau

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

10 Citations (Scopus)
60 Downloads (Pure)

Abstract

Pit-in-pit (PIP) excavations in an aquifer–aquitard system likely undergo catastrophic failures under the hydraulic uplift, the associated undrained stability problem, however, has not been well analyzed in the past. To this end, a hypothetical model of PIP braced excavation in typical soil layers of Shanghai, China is developed using the finite element limit analysis (FELA) tool. The FELA solutions of safety factors (FSs) against hydraulic uplift are verified with the results from the finite element analysis with strength reduction technique (SRFEA) and existing design approaches. Subsequently, FELA is employed to identify the triggering and failure mechanisms of PIP braced excavations subjected to hydraulic uplift. A series of parametric studies considering the various geometric configurations of the PIP excavation, undrained shear strengths of aquitard, and artesian pressures are carried out. The sensitivities of relevant design parameters are further assessed using a multivariate adaptive regression splines (MARS) model that is capable of accurately capturing the nonlinear relationships between a set of input variables and output variables in multi-dimensions. A MARS-based design equation used for predicting FS is finally presented using the artificial dataset from FELA for practical design uses.

Original languageEnglish
Pages (from-to)1-17
Number of pages17
JournalUnderground Space (China)
Volume7
Issue number6
DOIs
Publication statusPublished - 2022

Keywords

  • Finite element limit analysis
  • Hydraulic uplift
  • Multivariate adaptive regression splines
  • Pit-in-pit excavation
  • Undrained stability

Fingerprint

Dive into the research topics of 'Undrained stability of pit-in-pit braced excavations under hydraulic uplift'. Together they form a unique fingerprint.

Cite this