Pore water pressures and hydraulic conductivity in the slip zone of a clayey earthflow: Experimentation and modelling

2021 ◽  
pp. 106263
Author(s):  
C. Di Maio ◽  
J. De Rosa ◽  
R. Vassallo
Keyword(s):  
Hydraulic Conductivity ◽  
Pore Water ◽  
Slip Zone ◽  
Pore Water Pressures

scholarly journals Hydraulic Conductivity and Pore Water Pressures in a Clayey Landslide: Experimental Data

Geosciences ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 102 ◽  
Author(s):  
Caterina Di Maio ◽  
Jacopo De Rosa ◽  
Roberto Vassallo ◽  
Roberto Coviello ◽  
Giuseppe Macchia
Keyword(s):  
Experimental Data ◽  
Hydraulic Conductivity ◽  
Pore Water ◽  
Slip Surface ◽  
Field Tests ◽  
Hydrological Conditions ◽  
Pore Water Pressures ◽  
Landslide Body ◽  
Clay Formation ◽  
Stable Formation

To analyze the response to hydrological conditions of an instable slope in a structurally complex clay formation, the hydraulic conductivity of the subsoil was estimated and pore water pressures were monitored. Two types of field tests were carried out: falling head tests in the Casagrande piezometers and localized seepage measurements in test boreholes. The experimental data show that in a narrow band around the slip surface, the hydraulic conductivity is higher—more than two orders of magnitude—than that of the landslide body and of the stable formation. Furthermore, the data of a long-term monitoring by Casagrande piezometers and vibrating wire cells show that the response of pore water pressures to the site hydrological conditions along the shear band is far faster than in the landslide body and in the stable formation. The slip band seems largely connected to the atmosphere, and the water pressures in the band are correlated with the deep displacement rates of all the inclinometers crossing the active slip surface.

scholarly journals Changes in shaft resistance and pore water pressures during heating of an energy foundation

2020 ◽  
Vol 205 ◽  
pp. 05022
Author(s):  
Michael B. Reiter ◽  
Lydia Kurtz ◽  
Mohammed M. Attala ◽  
Tugce Baser
Keyword(s):  
Hydraulic Conductivity ◽  
Pore Water ◽  
Mechanical Response ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Thermally Induced ◽  
Shaft Resistance ◽  
Pore Water Pressures ◽  
Energy Foundations ◽  
Surrounding Soil

This study focuses on the evolution of shaft resistance during operation of a geothermal energy foundation installed in a saturated glacial till layer. Energy foundations are a sustainable alternative to traditional space heating and cooling approaches for buildings. Despite efficient operational performance, there are still valid concerns regarding the effects of heating on the structural performance of foundations. To investigate the effect of heating at the soil-pile interface, four drilled shafts are utilized as energy foundations on the Urbana-Champaign campus of the University of Illinois and instrumented. Although the energy foundations are not yet operational, a theoretical investigation is possible to understand the effects of heating on the evolution of thermally induced pore water pressures and the shaft resistance of an energy foundation. A thermo-poroelastic numerical model is validated against an analytical solution, then is used to analyze the thermo-mechanical response of the soil-structure system under different conditions. The results indicate that the evolution of pore water pressure is affected by the rate of heating and the hydraulic conductivity of the surrounding soil, as expected. Higher pore water pressures are generated in the case of low hydraulic conductivity and higher rates of heating. Prior to the dissipation of excess pore pressures, the changes in shaft resistance are variable and influenced by the thermally-induced deformation of the foundation and the surrounding soil.

scholarly journals Effect of Drainage and Consolidation on the Pore Water Pressures and Total Stresses within Backfilled Stopes and on Barricades

2019 ◽  
Vol 2019 ◽  
pp. 1-19 ◽  
Author(s):  
El Mustapha Jaouhar ◽  
Li Li
Keyword(s):  
Hydraulic Conductivity ◽  
Numerical Simulations ◽  
Young’S Modulus ◽  
Pore Water ◽  
Hydraulic Properties ◽  
Underground Mine ◽  
Filling Rate ◽  
Short Term ◽  
Pore Water Pressures ◽  
Backfilled Stopes

The pore water pressures (PWPs) and total stresses during the placement of a slurried backfill in underground mine stopes are the key parameters for the design of barricades, built to retain the backfill in the stopes. They can be affected by the drainage and consolidation of the backfill. Over the years, several studies have been reported on the pressure and stresses in backfilled stopes by accounting for the drainage and consolidation. Most of them focused on the pressure and stresses in the stopes, few specifically on the barricades. The effect of the number of draining holes commonly installed through the barricade has never been studied. In this paper, the influence of hydraulic properties and filling rate of the backfill, stope size, barricade location, and number of draining holes is systematically investigated with numerical simulations. The results show that the stresses in the backfilled stope and on the barricade largely depend on the filling rate, hydraulic conductivity, and Young’s modulus of the backfill. The draining holes can significantly decrease the PWP, but only slightly the total stresses on the barricades in short term.

scholarly journals Cylindrical Piezometer Responses in a Humified Fen Peat

1994 ◽  
Vol 25 (3) ◽  
pp. 167-182 ◽  
Author(s):  
Andrew J. Baird ◽  
Simon W. Gaffney
Keyword(s):  
Hydraulic Conductivity ◽  
Response Time ◽  
Pore Water ◽  
Test Data ◽  
Test Results ◽  
Recovery Test ◽  
Pore Water Pressures ◽  
Compressible Soil ◽  
Time Theory

Most studies of peat hydrology have concentrated on processes below the watertable where pore water pressures and hydraulic conductivity are measured using piezometers. While piezometer head recovery tests in poorly humified bog peats give responses similar to those expected from rigid soils, a number of studies have suggested that matrix compressibility might be important in affecting head recovery test results in well humified bog peats. Until now no data have been available for humified fen peats. We apply the response time theory of Brand and Premchitt (1982) for compressible soils, and Hvorslev (1951) for rigid soils, to head recovery test data obtained from open cylindrical piezometers installed in a humified fen peat in Somerset, England. To the best of our knowledge this is also the first quantitative application of compressible soil theory for piezometers to any peat. Our results show that compression and swelling of the peat matrix do affect the course of head recovery in the piezometers used in the study. We comment on the significance of this finding for the calculation of hydraulic conductivities and pore water pressures in this peat type.

Spatial Variation of Aquifer Parameters from Coastal Aquifers of Sindhudurg District, Maharashtra Using Pore-water Resistivity and Bulk Resistivity

2018 ◽  
Vol 1 (1) ◽  
pp. 28-40
Author(s):  
Suneetha Naidu ◽  
Gautam Gupta
Keyword(s):  
Hydraulic Conductivity ◽  
Pore Water ◽  
Coastal Aquifers ◽  
Hydraulic Parameters ◽  
Formation Factor ◽  
Bulk Resistivity ◽  
Good Correspondence ◽  
Aquifer System ◽  
Transverse Resistance ◽  
Water Resistivity

Estimation of hydraulic parameters in coastal aquifers is an important task in groundwater resource assessment and development. An attempt is made to estimate these parameters using geoelectrical data in combination with pore-water resistivity of existing wells. In the present study, 29 resistivity soundings were analysed along with 29 water samples, collected from the respective dug wells and boreholes, in order to compute hydraulic parameters like formation factor, porosity, hydraulic conductivity and transmissivity from coastal region of north Sindhudurg district, Maharashtra, India. The result shows some parts of the study area reveal relatively high value of hydraulic conductivity, porosity and transmissivity. Further, a negative correlation is seen between hydraulic conductivity and bulk resistivity. The hydraulic conductivity is found to vary between 0.014 and 293 m/day, and the transmissivity varied between 0.14 and 11,722 m2/day. The transmissivity values observed here are in good correspondence with those obtained from pumping test data of Central Ground Water Board. These zones also have high aquifer thickness and therefore characterize high potential within the water-bearing formation. A linear, positive relationship between transverse resistance and transmissivity is observed, suggesting increase in transverse resistance values indicate high transmissivity of aquifers. These relations will be extremely vital in characterization of aquifer system, especially from crystalline hard rock area.

A new approach to the stability analysis of thawing slopes

1980 ◽  
Vol 17 (4) ◽  
pp. 607-612 ◽  
Author(s):  
Luis E. Vallejo
Keyword(s):  
Stability Analysis ◽  
Water Content ◽  
Pore Water ◽  
Active Layer ◽  
Necessary Conditions ◽  
Mass Movements ◽  
New Approach ◽  
Pore Water Pressures ◽  
The Stability ◽  
Excess Pore

A new approach to the stability analysis of thawing slopes at shallow depths, taking into consideration their structure (this being a mixture of hard crumbs of soil and a fluid matrix), is presented. The new approach explains shallow mass movements such as skin flows and tongues of bimodal flows, which usually take place on very low slope inclinations independently of excess pore water pressures or increased water content in the active layer, which are necessary conditions in the methods available to date to explain these movements.

An analysis of the stability of thawing slopes, Ellesmere Island, Nunavut, Canada

2000 ◽  
Vol 37 (2) ◽  
pp. 449-462 ◽  
Author(s):  
Charles Harris ◽  
Antoni G Lewkowicz
Keyword(s):  
Shear Strength ◽  
Pore Water ◽  
Active Layer ◽  
Factor Of Safety ◽  
High Arctic ◽  
Ellesmere Island ◽  
Sensitivity Analyses ◽  
Pore Water Pressures ◽  
Hot Weather ◽  
The Stability

Active-layer detachment slides are locally common on Fosheim Peninsula, Ellesmere Island, where permafrost is continuous, the active layer is 0.5-0.75 m thick, and summer temperatures are unusually high in comparison with much of the Canadian High Arctic. In this paper we report pore-water pressures at the base of the active layer, recorded in situ on two slopes in late July and early August 1995. These data form the basis for slope stability analyses based on effective stress conditions. During fieldwork, the factor of safety within an old detachment slide on a slope at Hot Weather Creek was slightly greater than unity. At "Big Slide Creek," on a slope showing no evidence of earlier detachment failures, the factor of safety was less than unity on a steep basal slope section but greater than unity elsewhere. In the upper slope, pore-water pressures were only just subcritical. Sensitivity analyses demonstrate that the stability of the shallow active layer is strongly influenced by changes in soil shear strength. Possible mechanisms for reduction in shear strength through time include weathering of soils and gradual increases in basal active layer ice content. However, we suggest here that soil shearing during annual gelifluction movements is most likely to progressively reduce shear strengths at the base of the active layer from peak values to close to residual, facilitating the triggering of active-layer detachment failures.Key words: detachment slides, Ellesmere Island, pore-water pressures, gelifluction.

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