Thaw–Consolidation of Some Layered Systems

1973 ◽  
Vol 10 (4) ◽  
pp. 617-631 ◽  
Author(s):  
John F. Nixon
Keyword(s):  
Predictive Power ◽  
Considerable Time ◽  
Layered Systems ◽  
Fine Grained ◽  
Arctic Soils ◽  
Thaw Consolidation ◽  
Fine Grained Soil ◽  
The Stability ◽  
Excess Pore Pressures ◽  
Excess Pore

In order to assess the stability and deformation qualities of thawing arctic soils, a theory of thaw–consolidation must be established to predict the dissipation of excess pore fluids. The predictive power of current mathematical models is considerably enhanced by consideration of some common departures from homogeneity. In the first instance a permafrost profile of two different soil types is analyzed numerically, each layer having different thermal and geotechnical properties. The presence of a surficial layer, although minor in extent, may influence for a considerable time the behavior of the underlying layer. Secondly, the excess pore pressures in a fine-grained soil overlying an ice layer are treated theoretically, and the results suggest that foundation conditions over a thawing ice layer may not be as critical as sometimes is supposed.

Numerical analysis of strengthening by rockfill embankments on an upstream tailings dam

2013 ◽  
Vol 50 (4) ◽  
pp. 391-399 ◽  
Author(s):  
Linda Ormann ◽  
Muhammad Auchar Zardari ◽  
Hans Mattsson ◽  
Annika Bjelkevik ◽  
Sven Knutsson
Keyword(s):  
Finite Element ◽  
Minimum Cost ◽  
Tailings Dam ◽  
Consolidation Process ◽  
Downstream Side ◽  
Pore Pressures ◽  
Staged Construction ◽  
The Stability ◽  
Excess Pore Pressures ◽  
Excess Pore

The consolidation process could be slow in an upstream tailings dam; therefore, the stability can reduce due to an increase in excess pore pressures when the dam is raised. The safety of the dam can be enhanced by constructing rockfill berms on the downstream side. This paper presents a case study on the strengthening of an upstream tailings dam with rockfill berms. The finite element analyses were performed for modelling the staged construction of the dam and for optimizing the volume of the rockfill berms. The dam was raised in 11 stages; each stage consisting of a raising phase and a consolidation phase. The study shows that the slope stability of the dam reduced due to an increase of excess pore pressures during the raising phase. The stability of the dam was successfully improved by utilizing rockfill berms as supports on the downstream side. A technique has been presented to minimize the volume of the rockfill berms so that the required stability can be achieved at minimum cost. This paper shows that the finite element method can be a useful tool for modelling the consolidation behaviour of an upstream tailings dam and minimizing the volume of the rockfill berms that may be needed to maintain the stability of the dam during staged construction.

Pore Water Expulsion during Freezing

1975 ◽  
Vol 12 (1) ◽  
pp. 130-141 ◽  
Author(s):  
Edward C McRoberts ◽  
Norbert R. Morgenstern
Keyword(s):  
Experimental Evidence ◽  
Pore Water ◽  
Open System ◽  
Soil Type ◽  
Sandy Soils ◽  
Coarse Grained ◽  
Freezing Front ◽  
Fine Grained ◽  
Excess Pore Pressures ◽  
Excess Pore

When a freezing front advances through a saturated soil water may either be expelled or attracted to the freezing front depending upon soil type, stress level, and rate of freezing. Experimental evidence is considered which shows that coarse-grained sandy soils expel water under most conditions while fine grained soils can be made to expel water only at higher overburden pressures. A solution for the excess pore pressures that can be generated due to impeded drainage by pore water expulsion in an open system is presented.

Thaw–Consolidation Tests on Undisturbed Fine-grained Permafrost

1974 ◽  
Vol 11 (1) ◽  
pp. 202-214 ◽  
Author(s):  
J. F. Nixon ◽  
N. R. Morgenstern
Keyword(s):  
Heat Transfer ◽  
Thermal Properties ◽  
Surface Temperature ◽  
Pore Water ◽  
Excellent Agreement ◽  
Test Results ◽  
Fine Grained ◽  
Arctic Soils ◽  
Thaw Consolidation ◽  
Pore Water Pressures

A series of thaw–consolidation tests on undisturbed frozen samples of Arctic soils is described. The tests were carried out in a special oedometer, and thawing was induced by the application of a sudden constant increase in surface temperature. Settlements, pore water pressures, and rates of thaw are measured, and interpreted in the light of current theories of heat transfer and thaw–consolidation. Excellent agreement is obtained between predicted and observed thaw rates, using published thermal properties. The observed pore pressures and settlements also are consistent with predicted behavior.These test results on a variety of undisturbed permafrost samples increase the level of confidence when applying the theory of consolidation for thawing soils to natural permafrost deposits.

Behavior of a fine-grained soil during the Loma Prieta earthquake

1998 ◽  
Vol 35 (1) ◽  
pp. 146-158 ◽  
Author(s):  
Ross W Boulanger ◽  
Mark W Meyers ◽  
Lelio H Mejia ◽  
Izzat M Idriss
Keyword(s):  
Clayey Soil ◽  
Laboratory Data ◽  
Lateral Spreading ◽  
Liquid Limit ◽  
Silty Clay ◽  
Loma Prieta Earthquake ◽  
Fine Grained ◽  
Fine Grained Soil ◽  
Loma Prieta ◽  
Excess Pore Pressures

Results of an investigation into the behavior of a fine-grained clayey soil at Moss Landing during the 1989 Loma Prieta earthquake are presented. A deposit of this soil underlies portions of the Moss Landing Marine Laboratory that experienced up to 1.3 m of lateral spreading deformations during this magnitude 7 earthquake. Silty clay from the deposit erupted to the surface in a "soil boil" characteristic of liquefaction, during and immediately after the earthquake. A sample from the silty clay boil had a liquid limit of 38, a plasticity index of 17, and a <5 µm fraction of 24%, and thus would be considered nonliquefiable according to commonly used criteria. Analysis of cyclic triaxial test data suggests that portions of the silty clay deposit likely developed high residual excess pore pressures (ru,r approx 80-90%) and significant shear strains during the earthquake and thus likely contributed to the observed lateral deformations. The field and laboratory data show that commonly used criteria for identifying "liquefiable" clayey soils should be applied with caution and should not be indiscriminately viewed as a substitute for detailed laboratory and in situ testing of low plasticity fine-grained soils.Key words: liquefaction, cyclic loading, silt, clay, earthquake, case history.

Channeling during settling and self-weight consolidation of cohesive sediments

2008 ◽  
Vol 45 (6) ◽  
pp. 867-876 ◽  
Author(s):  
Soonkie Nam ◽  
Marte Gutierrez ◽  
Panayiotis Diplas
Keyword(s):  
Digital Camera ◽  
Small Scale ◽  
Cohesive Sediments ◽  
Pressure Measurements ◽  
Channel Formation ◽  
Factors Affecting ◽  
Fine Grained ◽  
Primary Mechanism ◽  
Excess Pore Pressures ◽  
Excess Pore

As a part of the settling and self-weight consolidation of fine-grained materials, a common but not widely recognized phenomenon randomly occurs, namely channeling or the formation of narrow vertical paths or “channels.” Channel formation can have important effects on the microstructure, consolidation, and shear strength characteristics of newly formed sediments. However, only a few studies have been performed on channeling. The causes of channel formation and the factors affecting it are still not fully understood. This paper presents the results of an experimental study of channel formation during settling and self-weight consolidation in fine-grained materials. Four types of fine-grained materials and different slurry concentrations were tested using large and small settling columns, and channel formation was observed using a high-resolution digital camera. The results indicate that the primary mechanism for channel formation is the coalescence of small-scale discontinuities between clusters of soil particles formed by flocculation. The stronger the degree of flocculation, the more prevalent is the formation of channels. Pore pressure measurements show the effects of channels in dissipating excess pore pressures in sediments undergoing self-weight consolidation.

Thaw–Consolidation Tests on Remoulded Clays

1973 ◽  
Vol 10 (1) ◽  
pp. 25-40 ◽  
Author(s):  
Norbert R. Morgenstern ◽  
Laurence B. Smith
Keyword(s):  
General Solution ◽  
Soil Behavior ◽  
One Dimensional ◽  
Pore Pressures ◽  
Thaw Consolidation ◽  
Degree Of Consolidation ◽  
Stress Boundary Conditions ◽  
Excess Pore Pressures ◽  
Stress Boundary ◽  
Excess Pore

A general solution to the problem of one-dimensional thaw–consolidation has been formulated by Morgenstern and Nixon (Can. Geotech. J. 8, p. 558, 1971). In order to assess the validity of the theory it was necessary to develop a special oedometer (permode) which could impose the necessary thermal and stress boundary conditions for one-dimensional thaw–consolidation.The permode permits the measurement of settlements, temperatures at various depths on the side of the sample, and excess pore pressures at the base of the sample during thaw–consolidation.Controlled thaw–consolidation tests were carried out on three types of remoulded clays. The resulting data showed that the excess pore pressures and the degree of consolidation in a thawing soil depend primarily on the thaw–consolidation ratio. The results obtained demonstrate that the theory adequately represents the soil behavior. Applications of the theory in practice are indicated.

scholarly journals Modeling the Compaction Characteristics of Fine-Grained Soils Blended with Tire-Derived Aggregates

2021 ◽  
Vol 13 (14) ◽  
pp. 7737
Author(s):  
Amin Soltani ◽  
Mahdieh Azimi ◽  
Brendan C. O’Kelly
Keyword(s):  
Energy Levels ◽  
Model Development ◽  
Dry Mass ◽  
Unit Weight ◽  
Power Functions ◽  
Compaction Characteristics ◽  
Practical Applications ◽  
Fine Grained ◽  
Practical Procedure ◽  
Fine Grained Soil

This study aims at modeling the compaction characteristics of fine-grained soils blended with sand-sized (0.075–4.75 mm) recycled tire-derived aggregates (TDAs). Model development and calibration were performed using a large and diverse database of 100 soil–TDA compaction tests (with the TDA-to-soil dry mass ratio ≤ 30%) assembled from the literature. Following a comprehensive statistical analysis, it is demonstrated that the optimum moisture content (OMC) and maximum dry unit weight (MDUW) for soil–TDA blends (across different soil types, TDA particle sizes and compaction energy levels) can be expressed as universal power functions of the OMC and MDUW of the unamended soil, along with the soil to soil–TDA specific gravity ratio. Employing the Bland–Altman analysis, the 95% upper and lower (water content) agreement limits between the predicted and measured OMC values were, respectively, obtained as +1.09% and −1.23%, both of which can be considered negligible for practical applications. For the MDUW predictions, these limits were calculated as +0.67 and −0.71 kN/m3, which (like the OMC) can be deemed acceptable for prediction purposes. Having established the OMC and MDUW of the unamended fine-grained soil, the empirical models proposed in this study offer a practical procedure towards predicting the compaction characteristics of the soil–TDA blends without the hurdles of performing separate laboratory compaction tests, and thus can be employed in practice for preliminary design assessments and/or soil–TDA optimization studies.

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.

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