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.

scholarly journals Ground-Penetrating Radar Evaluation of Moisture and Frost across Typical Saskatchewan Road Soils

2010 ◽  
Vol 2010 ◽  
pp. 1-9 ◽  
Author(s):  
Curtis Berthelot ◽  
Diana Podborochynski ◽  
Timo Saarenketo ◽  
Brent Marjerison ◽  
Colin Prang
Keyword(s):  
Dielectric Constant ◽  
Moisture Content ◽  
Ground Penetrating Radar ◽  
Soil Type ◽  
Structural Condition ◽  
Coarse Grained ◽  
Fine Grained ◽  
Survey Results ◽  
Ground Penetrating

This study was undertaken to evaluate the effect of soil type, moisture content, and the presence of frost on road substructure permittivity. Permittivity sensitivity of typical road soils was characterized in the laboratory to provide baseline dielectric constant values which were compared to field ground penetrating radar (GPR) survey results. Both laboratory devices, the complex dielectric network analyzer and the Adek Percometer, as well as the field GPR system were used in this study to measure the dielectric constant of soils. All three systems differentiated between coarse-grained and fine grained soils. In addition, at temperatures below freezing, all three systems identified an increase in water content in soils; however, when frozen, the sensitivity of dielectric constant across soil type and moisture content was significantly reduced. Based on the findings of this study, GPR technology has the ability to characterize in situ substructure soil type and moisture content of typical Saskatchewan road substructure soils. Given the influence of road soil type and moisture content on in-service road performance, this ability could provide road engineers with accurate estimates of in situ structural condition of road structures for preservation and rehabilitation planning and optimization purposes.

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 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.

scholarly journals Acceleration of Debris Flow Due to Granular Effect

2021 ◽  
Vol 9 ◽  
Author(s):  
Taiqiang Yang ◽  
Yong Li ◽  
Xiaojun Guo ◽  
Jun Zhang ◽  
Yu Jiang ◽  
...  
Keyword(s):  
Debris Flow ◽  
Pore Water ◽  
Slip Surface ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Coarse Grained ◽  
Flow Depth ◽  
Excess Pore Water Pressure ◽  
The Relationship ◽  
Excess Pore

Pore water pressure has been recognized as an important factor to enhance the mobility of debris flow moving in channel of very gentle slope. The creation and dissipation of pore water pressure are associated with interaction between grains. This study proposes a physical model for the pressure on mobility of flows with different granular configurations: the flow with overlying coarse-grained layer (i.e., inverse grading) and the flow with fully-mixed grains. The flow velocity is derived by the effective stress principle and the relationship between acceleration and pore water pressure is analyzed under different conditions. The results show that a high excess pore water pressure leads to high velocity of flow, and the pressure increases during the movement; and acceleration increases with time and flow depth under given pore water pressure. Moreover, compared with the flow with mixed grains, the flow with overlying coarse-grained layer is more effective to promote the excess pore water pressure and the liquefaction slip surface. Therefore, the internal drag reduction due to pore water pressure produces an acceleration effect on the flow.

Piezocone testing in underconsolidated clay

1989 ◽  
Vol 26 (4) ◽  
pp. 563-567 ◽  
Author(s):  
Yasuo Tanaka ◽  
Toshihiko Sakagami
Keyword(s):  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Excess Pore Pressure ◽  
Special Importance ◽  
Tip Resistance ◽  
Degree Of Consolidation ◽  
Excess Pore Pressures ◽  
Marine Clays ◽  
Excess Pore

This paper describes the results of piezocone testing that was carried out in underconsolidated soft marine clay in Osaka Bay. The obtained profiles of the tip resistance and the pore-water pressure were quite different from those for clay strata of normally consolidated state. It was apparent that a different approach is needed to interpret the test results for underconsolidated clay. The dissipation tests with the piezocone were performed at different elevations and indicated the excess pore-water pressures remaining in the stratum.The depth profile of excess pore pressure of underconsolidated clay is of special importance to the understanding of the degree of consolidation of the stratum. An effort was made in this paper to assess the excess pore pressures remaining in the clay based on the piezocone data obtained during penetration. An examination was made of available piezocone data of similar marine clays, of both normally consolidated and underconsolidated states. Based on this, a method was proposed for predicting the profile of pore-water pressure in underconsolidated clay using the piezocone data obtained during penetration. Key words: piezocone, field test, underconsolidated clay, excess pore-water pressure, interpretation.

scholarly journals Fully-coupled analysis for the behaviour of flexible retaining structures under seismic conditions

2020 ◽  
Vol 195 ◽  
pp. 01024
Author(s):  
Nicola Pontani ◽  
Kateryna Oliynyk ◽  
Claudio Tamagnini
Keyword(s):  
Pore Water ◽  
Dynamic Equilibrium ◽  
Coarse Sand ◽  
Coupled Analysis ◽  
Soil Water Retention ◽  
Retention Model ◽  
Hypoplastic Model ◽  
Excess Pore Pressures ◽  
Fully Coupled ◽  
Excess Pore

The study concerns the analysis of the behaviour of two propped reinforced-concrete diaphragm walls in coarse sand under seismic conditions. Fully-coupled dynamic equilibrium and pore water flow under unsaturated conditions for the soil have been taken into account, in order to assess the effects that the development of excess pore water pressures can have on the performance of such structures when dynamic conditions occur. The von Wolffersdorff hypoplastic model and the van Genuchten soil-water retention model have been used to describe the mechanical and retention behaviour of the sand. The Finite Element predictions of the soil and retaining structure behaviour show a significant dependence of the seismic performance of the structure – evaluated in terms of permanent displacements and structural loads, in view of the modern performance-based design criteria – on the excess pore pressures developed in the soil during the seismic shaking, even when dynamic liquefaction does not occur.

scholarly journals Experimental Research on Effect of Fines Content on Liquefaction Properties of Sand

2019 ◽  
Vol 8 (6S) ◽  
pp. 432-436
Keyword(s):  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Sandy Soils ◽  
Triaxial Tests ◽  
Liquefaction Resistance ◽  
Cyclic Triaxial Tests ◽  
Fines Content ◽  
Fine Grained ◽  
Cyclic Resistance

Liquefaction is a phenomenon mainly occurred in saturated fine grained soils under major earthquakes causes tremendous loss to infrastructure. From the literature it has been observed that liquefaction not only occurs in fine sands but also occurs in sands containing some amount of fines particles, which are of less than 75µ in size. Unfortunately there is no clear conclusions given as how effect the fines content on liquefaction resistance of sandy soils. In order to solve above mentioned problem this study was undertaken through stress-controlled cyclic triaxial tests to know the effect of fines content on liquefaction resistance of sandy soils. In this study the program of experimentation was done on base sand and sand mixed with four different combinations of fines like 10%, 20%, 30%, and 40% of fines with base sand by weight.. The main parameters changed in this work were percentage fines and shear stress ratio (CSR ), where the observed parameter was amount of pore water pressure and cycle of loading.. The result showed that, rate of pore water pressure generation during cyclic loading was largely affected by limiting silt content and density index. The trend observed as amount of pore water pressure is increased more than base sand with adding of fines content up to 20%, later the trend observed as reverse. And also noticed that more CSR value increases the pore water pressure generation and decreases the cyclic resistance

Correlation between dislocation, grain boundary and interface of duplex SS in stress corrosion cracking(SCC)

1990 ◽  
Vol 48 (4) ◽  
pp. 928-929
Author(s):  
Wang Zheng-fang ◽  
Z.F. Wang
Keyword(s):  
Stainless Steel ◽  
Thermal Cycle ◽  
Secondary Phase ◽  
Corrosion Cracking ◽  
Coarse Grained ◽  
Test Environment ◽  
Fine Grained ◽  
Evaluation Test ◽  
Welding Thermal Cycle ◽  
Micro Analysis

The main purpose of this study highlights on the evaluation of chloride SCC resistance of the material,duplex stainless steel,OOCr18Ni5Mo3Si2 (18-5Mo) and its welded coarse grained zone(CGZ).18-5Mo is a dual phases (A+F) stainless steel with yield strength:512N/mm2 .The proportion of secondary Phase(A phase) accounts for 30-35% of the total with fine grained and homogeneously distributed A and F phases(Fig.1).After being welded by a specific welding thermal cycle to the material,i.e. Tmax=1350°C and t8/5=20s,microstructure may change from fine grained morphology to coarse grained morphology and from homogeneously distributed of A phase to a concentration of A phase(Fig.2).Meanwhile,the proportion of A phase reduced from 35% to 5-10°o.For this reason it is known as welded coarse grained zone(CGZ).In association with difference of microstructure between base metal and welded CGZ,so chloride SCC resistance also differ from each other.Test procedures:Constant load tensile test(CLTT) were performed for recording Esce-t curve by which corrosion cracking growth can be described, tf,fractured time,can also be recorded by the test which is taken as a electrochemical behavior and mechanical property for SCC resistance evaluation. Test environment:143°C boiling 42%MgCl2 solution is used.Besides, micro analysis were conducted with light microscopy(LM),SEM,TEM,and Auger energy spectrum(AES) so as to reveal the correlation between the data generated by the CLTT results and micro analysis.

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