3D modelling of a deep excavation in a sloping site for the assessment of induced ground movements

Control of ground surface settlement induced by deep excavation is of major concern in order to attain safety of adjacent structures and utilities against excessive or differential settlements. Accurate prediction of ground surface movements is an important design criterion in the analysis and design of excavation supporting systems. Many codes of practice are based on a design criterion that satisfies a factor of safety preventing collapse of the system and its surrounding soil. In this research, finite element modeling is adopted to numerically simulate the performance of deep excavation systems and the associated ground movements. The soil behavior was simulated using two types of models; the Mohr-Coulomb model (MC) and the Hardening Soil Model (HS). Field data from monitoring a real deep excavation case history of a retaining system was considered to check the validity of the proposed numerical modeling. A simpler equivalent section replacing the multi-layered soil profile was verified. Then, a sensitivity study has been conducted to study the influence of major parameters that affect ground movements induced by deep excavation. The results of the parametric study were accomplished to construct design charts and drive empirical equations by implementing a design parameter, called the "Stiffness Ratio (R)”, that represents the supporting system stiffness. From these suggested charts and equations, the percentage of maximum vertical ground movements to wall height can be estimated.

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Distributions of ground movements parallel to deep excavations in clay

Canadian Geotechnical Journal ◽

10.1139/t05-091 ◽

2006 ◽

Vol 43 (1) ◽

pp. 43-58 ◽

Cited By ~ 39

Author(s):

Jill Roboski ◽

Richard J Finno

Keyword(s):

Error Function ◽

Ground Movement ◽

Deep Excavation ◽

Direction Parallel ◽

Ground Movements ◽

Movement Data ◽

Empirical Procedure ◽

Complementary Error Function ◽

Excavation Support ◽

Support Wall

An empirical procedure for fitting a complementary error function (erfc) to settlement and lateral ground movement data in a direction parallel to an excavation support wall is proposed based on extensive optical survey data obtained around a 12.8 m deep excavation in Chicago. The maximum ground movement and the height and length of an excavation wall define the erfc fitting function. The erfc fit is shown to apply to three other excavation projects where substantial ground movement data were reported.Key words: excavations, clays, ground movements, performance data.

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Ground movements due to pile driving in an excavation in soft soil

Canadian Geotechnical Journal ◽

10.1139/t98-071 ◽

1999 ◽

Vol 36 (1) ◽

pp. 152-160 ◽

Cited By ~ 6

Author(s):

I H Wong ◽

T S Chua

Keyword(s):

Precast Concrete ◽

Soft Soil ◽

Soft Clay ◽

Ground Movement ◽

Pile Driving ◽

Deep Excavation ◽

Ground Movements ◽

Concrete Piles ◽

Recent Project ◽

Story Building

An excavation in soft clay for the construction of a deep basement frequently is accompanied by large ground movements that may damage piles preinstalled at the base of the excavation. In a recent project involving the construction of a 10 m wide, 3.7 m deep drain, the construction method adopted entailed excavating the site soils and then driving precast concrete piles. The excavation was supported by steel sheet piles braced by one level of struts. Large settlements and horizontal movements of the ground were observed during pile driving. These movements exceeded those occurring during the excavation phase. Concrete aprons outside a one-story building adjacent to the excavation were badly damaged during excavation and pile driving. However, the building supported on steel piles was undamaged.Key words: deep excavation, sheet piles, pile driving, ground movement, basement construction.

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