Modeling excavations in urban areas: effects of past activities



A study evaluating the effect that pre-excavation activities have on computed responses of an urban excavation through soft—to medium clays is presented. Extensive field performance data were collected at the site located in Chicago, USA. The pre-excavation activities considered herein are the tunneling of existing subway tubes, constructing a school building adjacent to the excavation and installing a secant-pile support wall prior to start of excavation. These activities significantly influence the soil stresses at the site. The effects of these activities on computed responses are evaluated by either explicitly considering modeling them in the simulation or assuming the corresponding structure as wished in-p1ace in the finite element mesh. The various simulations are calibrated to optimize the fit between the observed field data and the computed results. The constitutive responses of the clay layers are simulated with the Hardening-Soil (H-S) model. Results show that different “optimal” input parameters are obtained depending on the way the preconstruction activities are modeled. The model is considered reliably calibrated when both the fit between computed and observed results is satisfactory and the best-fit values of the parameters are reasonable. This occurs only when all preexcavation activities are explicitly modeled.

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AUTORI: Calvello M., Finno R.J.
Numero di pagine: 9

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