scholarly journals Pore water pressure assessment in a forest watershed: Simulations and distributed field measurements related to forest practices

2004 ◽  
Vol 40 (2) ◽  
Author(s):  
Amod S. Dhakal ◽  
Roy C. Sidle
Keyword(s):  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Field Measurements ◽  
Forest Watershed ◽  
Forest Practices

Infiltration characteristics of two instrumented residual soil slopes

2003 ◽  
Vol 40 (5) ◽  
pp. 1012-1032 ◽  
Author(s):  
Illias Tsaparas ◽  
Harianto Rahardjo ◽  
David G Toll ◽  
Eng-Choon Leong
Keyword(s):  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Field Measurements ◽  
Residual Soil ◽  
Rainfall Runoff ◽  
Rainfall Events ◽  
Pore Water Pressures ◽  
Soil Slopes ◽  
Pressure Changes

This paper presents the analysis of a 12 month long field study of the infiltration characteristics of two residual soil slopes in Singapore. The field measurements consist of rainfall data, runoff data of natural and simulated rainfall events, and pore-water pressure changes during infiltration at several depths and at several locations on the two slopes. The analysis of the field measurements identifies the total rainfall and the initial pore-water pressures within the two slopes as the controlling parameters for the changes in the pore-water pressures within the slopes during infiltration.Key words: infiltration, rainfall, runoff, pore-water pressure, field measurements.

Field measurement of anchor forces, ground temperatures, and pore-water pressures behind a retaining structure in northwestern Ontario

1992 ◽  
Vol 29 (1) ◽  
pp. 112-116
Author(s):  
K. D. Eigenbrod ◽  
J. P. Burak
Keyword(s):  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Retaining Wall ◽  
Field Measurements ◽  
Strain Gauges ◽  
Ground Temperatures ◽  
Northwestern Ontario ◽  
Pore Water Pressures ◽  
Load Increase

Anchor forces, ground temperatures, and piezometric pressures were measured at a retaining wall in northwestern Ontario over a period of 2 years. The anchor forces were measured with strain gauges attached in pairs directly to the anchor rods. This method appeared practical in the field for time periods of less than 2 years as long as the strain gauges were carefully protected against moisture. The anchor forces increased from an average of 5 kN initially up to values of 50 kN during the winter periods and dropped during the summer periods back to the same values measured initially. The anchor forces were largely independent of pore-water pressure variations behind the wall. Rapid drawdown conditions, however, which were experienced during the second summer, were reflected in a load increase that was equivalent to the associated unloading effect in front of the wall. The pore-water pressures behind the wall were not noticeably affected by rapid drawdown, possibly due to the restraining effect of the anchors and the high rigidity of the low sheet pile wall. Ground temperatures at or below the groundwater table never dropped below 0 °C thus restricting the depth of frost penetration. Key words : anchor loads, freezing pressure, retaining walls, pore-water pressures, ground temperatures, field measurements.

scholarly journals Reduction of Groundwater Buoyancy on the Basement in Weak-Permeable/Impervious Foundations

2019 ◽  
Vol 2019 ◽  
pp. 1-11
Author(s):  
Jikai Zhou ◽  
Chenghuan Lin ◽  
Chen Chen ◽  
Xiyao Zhao
Keyword(s):  
Pore Water ◽  
Groundwater Level ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Field Measurements ◽  
Laboratory Model ◽  
Test Results ◽  
Underground Structures ◽  
Significant Difference ◽  
Reduction Coefficient

At present, groundwater buoyancy is directly calculated by Archimedes’ principle for the antifloating design of underground structures. However, this method may not be applicable to weak-permeable/impervious soils, e.g., clayey foundations, because there is a significant difference between the groundwater buoyancy obtained from field measurements and that calculated by Archimedes’ principle. In order to determine whether the method of calculating groundwater buoyancy in weak-permeable/impervious soil layers by Archimedes’ principle is reasonable, this paper investigated the groundwater buoyancy on the basement in such foundations through laboratory model tests. The following factors that may influence the magnitude of groundwater buoyancy were investigated: change of groundwater level, duration of pore water pressure, and buried depth of the basement. In this study, model test results show that the groundwater buoyancy obtained from measurements is evidently lower than that calculated by Archimedes’ principle. Reduction extent can be expressed by a “reduction coefficient,” which can be calculated by a fitting formula. Moreover, experimental groundwater buoyancy increases with the increase in the groundwater level, and it almost does not change with the growth of duration of pore water pressure. Reduction coefficient ranges between 0.25 and 0.52 depending on different buried depths of the basement. In general, experimental groundwater buoyancy decreases with the increase in the buried depth of the basement.

scholarly journals Characteristics of Pore-Water Pressure Response in Slopes During Rainfall

2019 ◽  
Vol 3 (1) ◽  
pp. 1-13
Author(s):  
Alfrendo Satyanaga Nio
Keyword(s):  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Field Measurements ◽  
Pressure Response ◽  
Residual Soil ◽  
Rainfall Events ◽  
Response Characteristics ◽  
Measurement Results ◽  
Soil Slopes

Field measurements of residual soil slopes are valuable for the assessment of slope stability during rainfall. Several residual soil slopes, which are predominantly unsaturated due to their deep groundwater table, were instrumented with tensiometer and rainfall gauge in order to study the response characteristics of the slopes during rainfall. Comprehensive field measurement results involving a large number of rainfall events are presented in the paper. The results show that the pore-water pressures in all instrumented slopes increased in a similar fashion during rainfall, but at different magnitudes depending on soil type. The pore-water pressure response characteristics can then be used to estimate the variation in factor of safety of the slope during rainfall.

Physical mechanics of aufeis growth

1981 ◽  
Vol 8 (2) ◽  
pp. 186-195 ◽  
Author(s):  
Douglas L. Kane
Keyword(s):  
Time Series ◽  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Time Lag ◽  
Field Measurements ◽  
Warming Trend ◽  
Braided Rivers ◽  
Time Series Analyses ◽  
Made In

All arctic travelers have encountered streams and braided rivers swollen with ice during the winter months. Numerous field measurements were made in an attempt to develop an understanding of the mechanics of aufeis growth. Piezometers were installed at several sites in central Alaska to measure the pressure variations of the fluid in the porous streambank. Time series analyses were utilized for correlating the variations in the observed pore pressures with climatic variables. It was concluded from the piezometer measurements of pore water pressure that subpermafrost groundwater or groundwater from nonpermafrost regions was the source of water for these ice deposits. Water from the active layer did not contribute to these accumulations of ice. Time series analysis revealed that pore water pressures started to increase following warming trends. A time lag existed between the start of a warming trend and the corresponding changes in pore water pressure; this time lag increased as the thickness of ice increased.

TIME TO THE END OF PRIMARY CONSOLIDATION (EOP) OF SOFT CLAYEY SOILS: CONCERNING THE EFFECT OF ATTERBERG’S LIMIT AND CYCLIC LOADING HISTORY

2019 ◽  
Vol 128 (2B) ◽  
pp. 29-41
Author(s):  
Trần Thanh Nhàn
Keyword(s):  
Cyclic Loading ◽  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Clayey Soils ◽  
Loading History ◽  
Cyclic Shear ◽  
Wide Range ◽  
Primary Consolidation ◽  
Time Required

In order to observe the end of primary consolidation (EOP) of cohesive soils with and without subjecting to cyclic loading, reconstituted specimens of clayey soils at various Atterberg’s limits were used for oedometer test at different loading increments and undrained cyclic shear test followed by drainage with various cyclic shear directions and a wide range of shear strain amplitudes. The pore water pressure and settlement of the soils were measured with time and the time to EOP was then determined by different methods. It is shown from observed results that the time to EOP determined by 3-t method agrees well with the time required for full dissipation of the pore water pressure and being considerably larger than those determined by Log Time method. These observations were then further evaluated in connection with effects of the Atterberg’s limit and the cyclic loading history.

Conjectures, Hypotheses, and Theories of Drumlin Formation (In memory of Stanislaw Baranowski)

1981 ◽  
Vol 27 (97) ◽  
pp. 503-505 ◽  
Author(s):  
Ian J. Smalley
Keyword(s):  
Shear Strength ◽  
Pore Water ◽  
Stress Level ◽  
Critical Stress ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Glacial Till ◽  
Forming Process ◽  
Stress Levels

AbstractRecent investigations have shown that various factors may affect the shear strength of glacial till and that these factors may be involved in the drumlin-forming process. The presence of frozen till in the deforming zone, variation in pore-water pressure in the till, and the occurrence of random patches of dense stony-till texture have been considered. The occurrence of dense stony till may relate to the dilatancy hypothesis and can be considered a likely drumlin-forming factor within the region of critical stress levels. The up-glacier stress level now appears to be the more important, and to provide a sharper division between drumlin-forming and non-drumlin-forming conditions.

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