Investigations of Hydraulic Properties in Crystalline Rock.

1983 ◽  
Vol 26 ◽  
Author(s):  
Leif Carlssn ◽  
Anders Winberg ◽  
Björn Rosander
Keyword(s):  
Rock Mass ◽  
Hydraulic Conductivity ◽  
Hydraulic Properties ◽  
Water Injection ◽  
Three Dimensional ◽  
Crystalline Rock ◽  
Fracture Frequency ◽  
Effective Hydraulic Conductivity ◽  
Constant Head ◽  
Total Fracture

ABSTRACTHydraulic properties of crystalline rock from four potential repository sites in Sweden were analysed. The hydraulic conductivity of the bedrock was established by means of transient water-injection tests with constant head conducted in 25 m sections. The bedrock at the sites was divided into different hydraulic units. An effective hydraulic conductivity was calculated for the rock mass at each site. This was done on the basis of the frequency distribution of all measured values within this unit. A log-nornal distribution was found to fit the data reasonably well. Regression analysis of hydraulic conductivity as a function of depth indicated similar relationships between the four sites. At a depth of 500 m the effective hydraulic conductivity for three-dimensional flow was about 5.10-11 m/s.The fracture frequency of the sites was established from existing core-logs. At depths of about 500 m the mean fracture frequency of the rock mass at the four sites was 1.8-2.5 fractures per meter. Of this total fracture frequency only a a certain proportion is considered to be hydraulically conductive. This proportion was established from results of hydraulic tests perforned in 2 or 3 m sections. Results obtained indicated a frequency of hydraulically conductive fractures of 0.1-0.3 fractures per meter in the rock mass at depths below 300 m.

Utilisation d'un modèle stochastique de réseaux de fractures pour étudier les propriétés hydrauliques d'un massif fissuré

1989 ◽  
Vol 26 (2) ◽  
pp. 313-323
Author(s):  
Lahcen Ait-Ssi ◽  
Jean-Pierre Villeneuve ◽  
Alain Rouleau
Keyword(s):  
Rock Mass ◽  
Hydraulic Properties ◽  
Model Simulation ◽  
Water Injection ◽  
Stochastic Simulations ◽  
Fracture Aperture ◽  
Modèle Stochastique ◽  
Fracture System ◽  
Fracture Porosity ◽  
Fractured Medium

This study of the hydraulic properties of a fractured rock mass is based on data from field injection tests and fracture measurements, and on simulations of the fracture system in the bedrock upstream from the Daniel Johnson dam at Manic 5. Analysis of water injection tests indicates that the bedrock can be divided into two zones with respect to the permeability. The more permeable zone, which is the object of this study, shows a log-normal distribution of the hydraulic conductivities.Using several stochastic simulations of fracture networks, the fracture aperture has been adjusted gradually to reproduce the rock mass permeability estimated from injection tests. The results show that the fracture system geometry, as well as the fracture porosity and the fracture lengths and densities, influences widely the hydraulic properties of a fractured medium and particularly the fracture porosity. Also, the estimation of the fracture porosity is sensitive to a number of other factors, including the assumed hydraulic boundary conditions, the field estimation of the hydraulic conductivities, and the orientation of the simulation planes. Key words: fissured media, fracture porosity, stochastic model, simulation, sensitivity analysis, dam.

scholarly journals Finite-Difference Numerical Simulation of Dewatering System in a Large Deep Foundation Pit at Taunsa Barrage, Pakistan

2019 ◽  
Vol 11 (3) ◽  
pp. 694 ◽  
Author(s):  
Ijaz Ahmad ◽  
Muhammad Tayyab ◽  
Muhammad Zaman ◽  
Muhammad Anjum ◽  
Xiaohua Dong
Keyword(s):  
Hydraulic Conductivity ◽  
Finite Difference ◽  
Three Dimensional ◽  
Rehabilitation Program ◽  
Diaphragm Wall ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Deep Foundation Pit ◽  
Constant Head ◽  
Design Depth

This study investigates a large deep foundation pit of a hydraulic structure rehabilitation program across the Indus river, in the Punjab province of Pakistan. The total area of the construction site was 195,040 m2. Two methods, constant head permeability test and Kozeny–Carman equation, were used to determine the hydraulic conductivity of riverbed strata, and numerical simulations using the three-dimensional finite-difference method were carried out. The simulations first used hydraulic conductivity parameters obtained by laboratory tests, which were revised during model calibration. Subsequently, the calibrated model was simulated by different aquifer hydraulic conductivity values to analyze its impact on the dewatering system. The hydraulic barrier function of an underground diaphragm wall was evaluated at five different depths: 0, 3, 6, 9, and 18 m below the riverbed level. The model results indicated that the aquifer drawdown decreases with the increase in depth of the underground diaphragm wall. An optimal design depth for the design of the dewatering system may be attained when it increases to 9 m below the riverbed level.

Physical properties of the mor layer in a Scots pine stand I. Hydraulic conductivity

1997 ◽  
Vol 77 (4) ◽  
pp. 627-634 ◽  
Author(s):  
A. Laurén ◽  
J. Heiskanen
Keyword(s):  
Hydraulic Conductivity ◽  
Pinus Sylvestris ◽  
Scots Pine ◽  
Hydraulic Properties ◽  
Matric Potential ◽  
Unsaturated Hydraulic Conductivity ◽  
Undisturbed Samples ◽  
Constant Head ◽  
Humified Peat ◽  
Properties Of Soil

Hydraulic conductivity in the mor layer of a Scots pine (Pinus sylvestris L.) stand was measured in undisturbed samples using the constant-head permeameter and instantaneous-profile method. Saturated hydraulic conductivity (Ks) averaged 2.9 × 102 m d−1. With a decrease in matric potential (ψ) from −4 kPa to −70 kPa the unsaturated hydraulic conductivity (K(ψ)) decreased from 3.1 × 10−3 to 1.1 × 10−8 m d−1. Ks and K(ψ) were similar to those reported in the literature for low-humified peat. The variation in hydraulic conductivity within a stand of Scots pine at a given matric potential was large, ranging from one to two orders of magnitude. Key words: F horizon, humus, hydraulic properties of soil

scholarly journals Three-Dimensional Numerical Investigation of Coupled Flow-Stress-Damage Failure Process in Heterogeneous Poroelastic Rocks

Energies ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 1923 ◽  
Author(s):  
Shikuo Chen ◽  
Chenhui Wei ◽  
Tianhong Yang ◽  
Wancheng Zhu ◽  
Honglei Liu ◽  
...  
Keyword(s):  
Rock Mass ◽  
Flow Stress ◽  
Failure Mechanism ◽  
Hydraulic Properties ◽  
Failure Process ◽  
Three Dimensional ◽  
Permeability Evolution ◽  
Heterogeneous Rocks ◽  
Hydraulic Conditions ◽  
Stress Damage

The failure mechanism of heterogeneous rocks (geological materials), especially under hydraulic conditions, is important in geological engineering. The coupled mechanism of flow-stress-damage should be determined for the stability of rock mass engineering under triaxial stress states. Based on poroelasticity and damage theory, a three-dimensional coupled model of the flow-stress-damage failure process is studied, focusing mainly on the coupled characteristics of permeability evolution and damage in nonhomogeneous rocks. The influences of numerous mesoscale mechanical and hydraulic properties, including homogeneity, residual strength coefficient, loading rates, and strength criteria, on the macro mechanical response are analyzed. Results reveal that the stress sensitive factor and damage coefficient are key variables for controlling the progress of permeability evolution, and these can reflect the hydraulic properties under pre-peak and post-peak separately. Moreover, several experiments are conducted to evaluate the method in terms of permeability evolution and failure process and to verify the proposed two-stage permeability evolution model. This model can be used to illustrate the failure mechanics under hydraulic conditions and match different rock types. The relation of permeability with strain can also help confirm appropriate rock mass hydraulic parameters, thereby enhancing our understanding of the coupled failure mechanism in rock mass engineering.

scholarly journals Experimental investigation to characterize simple versus multi scaling analysis of hydraulic conductivity at a mesoscale

2021 ◽  
Author(s):  
Guglielmo Federico Antonio Brunetti ◽  
Samuele De Bartolo ◽  
Carmine Fallico ◽  
Ferdinando Frega ◽  
Maria Fernanda Rivera Velásquez ◽  
...  
Keyword(s):  
Hydraulic Conductivity ◽  
Spatial Variability ◽  
Hydraulic Properties ◽  
Scaling Laws ◽  
Scaling Analysis ◽  
Field Scale ◽  
Porous Formation ◽  
Proper Design ◽  
First Time

AbstractThe spatial variability of the aquifers' hydraulic properties can be satisfactorily described by means of scaling laws. The latter enable one to relate the small (typically laboratory) scale to the larger (typically formation/regional) ones, therefore leading de facto to an upscaling procedure. In the present study, we are concerned with the spatial variability of the hydraulic conductivity K into a strongly heterogeneous porous formation. A strategy, allowing one to identify correctly the single/multiple scaling of K, is applied for the first time to a large caisson, where the medium was packed. In particular, we show how to identify the various scaling ranges with special emphasis on the determination of the related cut-off limits. Finally, we illustrate how the heterogeneity enhances with the increasing scale of observation, by identifying the proper law accounting for the transition from the laboratory to the field scale. Results of the present study are of paramount utility for the proper design of pumping tests in formations where the degree of spatial variability of the hydraulic conductivity does not allow regarding them as “weakly heterogeneous”, as well as for the study of dispersion mechanisms.

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