The energy reduction factor (FER) to model sensitive clay flowslides using in situ geotechnical and rheological data

A novel reconstitution process is developed to reconstitute remoulded quick clay with comparable sensitivities to the sampled undisturbed material. This laboratory method is based on scaling some of the main in situ processes involved in the development of sensitivity in a natural quick clay. It is shown that high sensitivity can be regained in a sequence of scaled flocculated sedimentation stages followed by consolidation and leaching in a geotechnical centrifuge. The suggested approach is a promising method for fast reconstitution of sensitive clay samples for element and physical model testing in a geotechnical laboratory.

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Characterizing spatial variability of a clay by geostatistics

Canadian Geotechnical Journal ◽

10.1139/t95-001 ◽

1995 ◽

Vol 32 (1) ◽

pp. 1-10 ◽

Cited By ~ 51

Author(s):

Paul Chiasson ◽

Jean Lafleur ◽

Michel Soulié ◽

K. Tim Law

Keyword(s):

Spatial Variability ◽

Linear Trend ◽

Nonstationary Problem ◽

Test Results ◽

Stochastic Representation ◽

Geostatistical Approach ◽

Generalized Covariance ◽

Sensitive Clay ◽

Standard Deviations

This paper presents a characterization of the variability of a lightly overconsolidated and highly sensitive clay deposit located near Saint-Hilaire, 50 km east of Montréal. The geotechnical investigation consisted of in situ and laboratory tests. The variability of the in situ test results is the subject of this paper. The working hypothesis assumes that piezocone and vane test results may be modelled by a random function. This is done on the basis of a geostatistical approach. In situ vane and piezocone tests are found to increase with depth following a linear trend. This is a nonstationary problem and inference of the autocorrelation function must be made through the estimation of a generalized covariance. Results for both types of tests give the same shape of generalized covariance. Measurements made with both testing devices yield the same 2 m autocorrelation distance but the standard deviations are different. The standard deviations for the piezocone cone resistance, pore pressure behind the cone tip, and sleeve friction are 74, 34, and 2.1 kPa, respectively. Vane measurements have a standard deviation of 4.9 kPa. Results are also presented for the estimation of the vertical linear trend and for the statistical distributions of fluctuations. Key words : sensitive clay, spatial variability, stochastic representation, geostatistics, piezocone testing, vane testing.

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Lateral compression response of overlapping jet-grout columns with geometric imperfections in radius and position

Canadian Geotechnical Journal ◽

10.1139/cgj-2017-0280 ◽

2018 ◽

Vol 55 (9) ◽

pp. 1282-1294 ◽

Cited By ~ 11

Author(s):

Yong Liu ◽

Yutao Pan ◽

Miaomiao Sun ◽

Jun Hu ◽

Kai Yao

Keyword(s):

Prediction Models ◽

Reduction Factor ◽

Strength Reduction ◽

Statistical Characteristics ◽

Strength Reduction Factor ◽

Geometric Imperfections ◽

Radius Variation ◽

Positioning Errors ◽

Random Nature

Spatial variability in the radius of a jet-grout column is commonly encountered in practice. Although various prediction models for the column radius are available, they have been generally used to predict a nominal radius. The radius variation within a column has been seldom considered. In this study, the intracolumn radius variation was simulated as a lognormal stochastic process. This was done based on the existing prediction models where the column radius can be correlated with the undrained shear strength of in situ soils. A slab consisting of overlapping jet-grout columns was considered. The slab serves as an earth-retaining stabilizing structure in a deep excavation. The effects of radius variation on the mass performance of the slab were examined with the finite-element method. In addition, the positioning errors in jet-grout columns were also investigated. Owing to the random nature of the radius variation, Monte-Carlo simulations were performed to estimate the statistical characteristics of the mass performance of the slab. A strength reduction factor was introduced and tabulated to account for the effects of geometric imperfections in the column radius and column position. With the strength reduction factor, practitioners could quantitatively evaluate the effects of these geometric imperfections in design considerations. Practical recommendations on the column length and column spacing were also proposed.

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Flexible Temporary Shield in Soft and Sensitive Clay: 3D FE Modelling of Experimental Field Test

Modelling and Simulation in Engineering ◽

10.1155/2021/6626750 ◽

2021 ◽

Vol 2021 ◽

pp. 1-15

Author(s):

Miah Alam ◽

Omar Chaallal ◽

Bertrand Galy

Keyword(s):

Field Test ◽

Numerical Study ◽

Earth Pressure ◽

Maximum Load ◽

Reduction Factor ◽

Fe Analysis ◽

Soil Pressure ◽

Fe Modelling ◽

Flexible Wall ◽

Sensitive Clay

A finite-element (FE) numerical study using PLAXIS-3D software was carried out to reproduce and validate a full-scale experimental in situ test and to investigate the earth pressure on a flexible temporary trench box shield in soft and sensitive clay soil. The excavation trench model was 6 m (20 ft) deep and was considered as nonlinear and anisotropic clay. A 45 kPa (0.94 ksf) surface overload on top of the soil near the trench box was also simulated to produce a maximum load case on the flexible wall of the shield. Both Mohr-Coulomb (MC) and hardening soil (HS) constitutive soil models were considered for FE analysis. Different values of the modulus reduction factor (MRF) and the coefficient of earth pressure at rest ( K 0 ) were considered to validate the model. For a specific shear strength profile, FE analysis with a linear elastoplastic soil model showed relatively small differences in soil pressure with the field test results along the depth of the trench. Results were also compared with the predictions of well-established analytical formulae.

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Quantification of Energy-Related Parameters for Near-Fault Pulse-Like Seismic Ground Motions

Applied Sciences ◽

10.3390/app10217578 ◽

2020 ◽

Vol 10 (21) ◽

pp. 7578 ◽

Cited By ~ 1

Author(s):

Omar AlShawa ◽

Giulia Angelucci ◽

Fabrizio Mollaioli ◽

Giuseppe Quaranta

Keyword(s):

Ground Motions ◽

Time History ◽

High Energy ◽

Reduction Factor ◽

Hysteretic Behavior ◽

Energy Reduction ◽

Input Energy ◽

Hysteretic Energy ◽

Analysis And Design ◽

Near Fault

An energy-based approach facilitates the explicit consideration of the damage associated with both maximum displacements and cumulative plastic deformations under earthquakes. For structural systems that can undergo pulse-like seismic ground motions close to causative faults, an energy-based approach is deemed especially appropriate with respect to well-established force- or displacement-based strategies. In such a case, in fact, most of the damage is attributable to the dominant pulse-like component, which usually occurs into the velocity time history of the seismic ground motion, thus implying high energy levels imparted to a structural system. In order to enable the implementation of an energy-based approach in the analysis and design of structures under near-fault pulse-like seismic ground motions, this study presents a comprehensive numerical investigation about the influence of seismological parameters and hysteretic behavior on the spectra of the following energy-related parameters: inelastic absolute and relative input energy; input energy reduction factor; hysteretic energy dissipation demand; hysteretic energy reduction factor; dimensionless cumulative plastic deformation ratio. Closed-form approximations are proposed for these spectra, and the numerical values of the corresponding parameters have been also calibrated (with reference to both mean and standard deviation values) as functions of earthquake magnitude, type of hysteretic behavior (i.e., non-degrading or degrading) and ductility level. The outcomes of this study are meant to support the derivation of design spectra for the energy-based seismic design of structures under near-fault pulse-like seismic ground motions.

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Pressure Distribution Model for Pressure Garment Development

Research Journal of Textile and Apparel ◽

10.1108/rjta-19-02-2015-b001 ◽

2015 ◽

Vol 19 (2) ◽

pp. 1-8

Author(s):

Mohamed Najib Bin Salleh ◽

Memis Acar ◽

Neil D. Burns

Keyword(s):

Pressure Distribution ◽

Reduction Factor ◽

The Body ◽

Digital Data ◽

Distribution Model ◽

Radius Of Curvature ◽

Body Segment ◽

3D Data ◽

Custom Made

This paper reports a pressure distribution model that will predict the pressure applied by a pressure garment onto a wounded body segment which could facilitate the production of custom made pressure garments. The model is generated by using the 3D data of the wounded body segment of a patient which are obtained by a non-intrusive non-contact measurement system. The circumference of the body segment is calculated from scanned digital data. Then, a circumference reduction factor is calculated to determine the circumference of the pressure garment in order to apply the design pressure by using a specific fabric with an experimentally determined modulus of elasticity in the circumferential direction. Then, the radius of curvature for each data point in a given layer is calculated and the pressure applied is obtained. Finally, a 3D pressure distribution model for the whole wounded part is constructed by stacking the pressure maps of adjacent layers. The model is verified through a comparison with the actual pressure measured by using custom made pressure garments and volunteer subjects. The comparison shows reasonable agreement. The model enables garment manufacturers/therapists to evaluate the effectiveness of a custom designed pressure garment before it is manufactured and eliminates the need for in-situ pressure measurements.

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Behavior of Installation for Suction Anchor in Soft Clay

29th International Conference on Ocean, Offshore and Arctic Engineering: Volume 1 ◽

10.1115/omae2010-20838 ◽

2010 ◽

Author(s):

Ling-ling Li ◽

Heng-jun Dai ◽

Li-zhong Wang

Keyword(s):

Shear Strength ◽

Soft Clay ◽

Reduction Factor ◽

Strength Reduction Factor ◽

Displacement Vectors ◽

Key Factor ◽

Sensitive Clay ◽

Soil Flow ◽

Penetration Behavior ◽

Shear Strength Reduction

Suction anchor foundations are being increasingly used for a variety of offshore application. In designing a suction anchor geotechnical engineering must consider the installation process as well as the in-place performance. The main objective of the present study was to investigate the penetration behavior of the suction anchor in normally consolidated and sensitive clay. Numerical analyses are preformed to study the installation by suction in soft clay. The effects of the penetration depth, the shear strength ratio along the interface between the anchor and the clay on the installation process on the failure mechanism and the pattern of soil flow at the anchor tip during installation are discussed in detail. The shear strength reduction factor is the key factor of the installation procedure, and it has a strong effect on the limited installable aspect ratio. The displacement vectors show that the clay beneath the anchor tip will move up inside the anchor when the anchor moves down while soils beneath the tip as well as soils outside the skirt wall also flow inward at the reverse bearing capacity failure. Finally, some conclusions are made, which can be useful in practice.

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Thirty years of secondary consolidation in sensitive marine clay

Canadian Geotechnical Journal ◽

10.1139/t90-042 ◽

1990 ◽

Vol 27 (3) ◽

pp. 315-319 ◽

Cited By ~ 6

Author(s):

C. B. Crawford ◽

M. Bozozuk

Keyword(s):

Key Words ◽

Surface Load ◽

Marine Clay ◽

Case Record ◽

Final Value ◽

Effective Stresses ◽

Sensitive Clay ◽

Sensitive Marine Clay

This case record shows that when a surface load is applied to a sensitive, normally consolidated clay, the effective stresses increase rapidly to the measured preconsolidated stresses, and remain at that level while consolidation continues for several decades. Only after more than 30 years was there an indication that the in situ effective stresses were beginning to increase to their final value. These observations have important implications with respect to the design of foundations in such areas. Key words: consolidation, foundations, secondary consolidation, sensitive clay settlements, marine clay.

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