Deformations and Pore Pressures Beneath Gravity Structures

2008 ◽  
pp. 295-295-11
Author(s):  
IK Lee ◽  
T Staunton ◽  
W White ◽  
WO Yandell
Keyword(s):  
Pore Pressures

scholarly journals Downdrag Measurements on a 160-Ft Floating Pipe Test Pile in Marine Clay

1972 ◽  
Vol 9 (2) ◽  
pp. 127-136 ◽  
Author(s):  
M. Bozozuk
Keyword(s):  
Skin Friction ◽  
Compressive Load ◽  
Marine Clay ◽  
Positive Skin ◽  
Negative Skin Friction ◽  
Pore Pressures ◽  
Excess Pore Pressures ◽  
Test Pile ◽  
Excess Pore

Large negative skin friction loads were observed on a 160 ft (49 m) steel pipe test pile floating in marine clay. The test pile was driven, open-ended, on the centerline of a 30 ft (9 m) high granular approach fill on the Quebec Autoroute near Berthierville. Since the installation was made in 1966 the fill has settled 21 in. (53 cm), dragging the pile down with it. Negative skin friction acting along the upper surface of the pile was resisted by positive skin friction acting along the lower end as it penetrated the underlying clay. Under these conditions the pile compressed about [Formula: see text] (2 cm). Analysis of the axial strains indicated that a peak compressive load of 140 t developed at the inflection point between negative and positive skin friction 73 ft (22 m) below the top of the pile. Negative and positive skin friction acting on the upper surface of the pile exceeded the in situ shear strength and approached the drained strength of the soil where excess pore water pressures had dissipated. At the lower end where the positive excess pore pressures were high and relative movement between the pile and the soil was large, the positive skin friction approached the remoulded strength as measured with the field vane. Skin friction was increasing, however, as positive escess pore pressures dissipated.This paper shows that skin friction loads are related to the combination of (a) in situ horizontal effective stresses, (b) horizontal stresses due to embankment loads, and (c) horizontal stresses due to differential settlement of the fill.

Experiences with alluvial foundations for earth dams in the Prairie provinces

1979 ◽  
Vol 16 (2) ◽  
pp. 255-271 ◽  
Author(s):  
N. Peters ◽  
K. N. Lamb
Keyword(s):  
Rational Design ◽  
Preliminary Design ◽  
Empirical Relationships ◽  
Design Concepts ◽  
Theoretical Design ◽  
Pore Pressures ◽  
Wide Range ◽  
Thick Layers ◽  
Limited Testing ◽  
Prairie Provinces

The foundations for numerous dams in proglacial and interglacial valleys in the Prairie provinces consist of soft alluvial soils. The deposits are up to 60 m deep, and contain thick layers of clay interspersed with lenses and layers of silt, sand, and gravel.This paper describes the damsite investigation and laboratory testing required, the design methods and construction procedures used, and the foundation performance observed during and after construction. A number of empirical relationships between index tests and physical properties of the soils, which provide useful guidelines for preliminary design, are presented.The design approach has gradually evolved from an empirical design with limited testing to a more rational design based on detailed investigations and thorough instrumentation. Increased reliance is placed on observational apparatus to monitor movements and pore pressures to confirm design assumptions as construction proceeds. The theoretical design is always checked with former designs of dams that have performed satisfactorily.Safe economical dams have been constructed in spite of large deformations and high pore pressures. Two case histories illustrate the wide range in dam design for alluvial foundations. The first shows an older design cross section with modifications required to ensure a stable dam, and the second describes a recently constructed dam that incorporates many of the latest design concepts.

scholarly journals Inferred pore pressures at the Costa Rica subduction zone: implications for dewatering processes

2000 ◽  
Vol 177 (3-4) ◽  
pp. 193-207 ◽  
Author(s):  
Demian M. Saffer ◽  
Eli A. Silver ◽  
Andrew T. Fisher ◽  
Harold Tobin ◽  
Kate Moran
Keyword(s):  
Costa Rica ◽  
Subduction Zone ◽  
Pore Pressures

Poro-Elasto-Plastic Model for Wave-Induced Liquefaction

2014 ◽  
Author(s):  
Chengcong Liao ◽  
Hongyi Zhao ◽  
Dong-Sheng Jeng
Keyword(s):  
Two Dimensional ◽  
Plastic Model ◽  
Centrifuge Tests ◽  
Pore Pressures ◽  
Proposed Model ◽  
Progressive Waves ◽  
Plastic Components ◽  
Excess Pore Pressures ◽  
Wave Induced ◽  
Pore Pressure Build Up

In this study, a two-dimensional poro-elasto-plastic model for the wave-induced liquefaction in a porous seabed was presented. Two mechanisms of the wave-induced pore pressures were considered. Both elastic components (for oscillatory) and the plastic components (for residual) were integrated to predict the wave-induced excess pore pressures in marine sediments. The proposed 2D poro-elasto-plastic model allows for the pore pressure build-up process in a sandy seabed. The proposed model overall agreed well with the previous wave experiments and centrifuge tests. Numerical example shows that the pattern of progressive waves -induced liquefaction gradually changed from 2D to 1D.

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