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Performance-based procedures represent an improvement over current state-of-practice procedures that treat the assessment of seismic demand and engineering response parameters independently. Procedures used in current practice generally provide estimates of liquefaction-induced ground settlement that are inconsistent with the desired ground settlement hazard level. A recently developed probabilistic procedure to estimate liquefaction-induced ground settlement is employed to develop a new performance-based procedure that estimates ground settlement which accounts for key sources of uncertainty. The ground-motion intensity and ground settlement estimations are integrated in the proposed procedure to produce hazard curves for liquefaction-induced ground settlement. The hazard curve for ground settlement links different hazard levels with their corresponding values of ground settlement by evaluating a wide range of ground-motion intensities and site characterization parameters with their associated uncertainties. The proposed performance-based procedure also permits the evaluation of different sources of uncertainty and their effects on the ground settlement estimate.
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Semi-Empirical Method for Excavation-Induced Surface Displacements—Los Angeles Metro K Line Crenshaw/LAX Transit Project
Estimating excavation-induced ground surface displacements in urban areas is needed to assess potential structure damage. Empirical settlement distribution models have been widely used to estimate the zone of influence and ground response behind braced excavation walls. Three underground station excavations, part of the Los Angeles Metro’s K Line Crenshaw/LAX Transit Project, offer a unique opportunity to collect field instrumentation data to improve estimates of ground deformations. One excavation employed cross-lot braces and soldier piles and wood lagging while the other two were supported by cross-lot braces and stiffer Cutter-Soil-Mixing (CSM) walls. For the excavations with stiff support systems and relatively small wall movements, upward surface displacement or heave governed the ground surface response, while surface settlement was measured at the excavation with the more flexible wall system. This heave behavior is often masked by settlement caused by relatively large wall movements, and is thus commonly disregarded. By idealizing the excavation unloading as an upward strip load at the ground surface, the Boussinesq solution for elastic upward movement can be used in combination with a settlement component resulting from lateral wall movements to estimate the magnitude and distribution of excavation-induced surface displacements.
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- PAR ID:
- 10461964
- Editor(s):
- Rathje, Ellen; Montoya, Brina; Wayne, Mark
- Publisher / Repository:
- American Society of Civil Engineers (ASCE)
- Date Published:
- Journal Name:
- ASCE Geo-Congress 2023
- ISSN:
- 9780784484708
- ISBN:
- 9780784484708
- Page Range / eLocation ID:
- 492 to 500
- Subject(s) / Keyword(s):
- Excavations, SOE
- Format(s):
- Medium: X
- Location:
- https://ascelibrary.org/doi/epdf/10.1061/9780784484708.046
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.1061/9780784484708.046
