DEVELOPMENTS IN HYDRAULIC CONDUCTIVITY RESEARCH Phần pot

Cabral Empirical Approaches to Estimating Hydraulic Conductivity 111 Correlations between Hydraulic Conductivity and Selected Hydrogeological Properties of Rocks 113 Stanisław Żak Rock

DEVELOPMENTS IN HYDRAULIC CONDUCTIVITY

RESEARCHEdited by Oagile Dikinya

Developments in Hydraulic Conductivity Research

Edited by Oagile Dikinya

Published by InTech

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of Hydraulic Conductivity for Fractured Rocks 3

Yifeng Chen and Chuangbing Zhou

Influence of Degree of Saturation in the Electric Resistivity-Hydraulic Conductivity Relationship 49

Mohamed Ahmed Khalil and Fernando A Monterio Santos

Hydraulic Conductivity and Water Retention Curve

of Highly Compressible Materials- From a Mechanistic Approach through Phenomenological Models 71

Serge-Étienne Parent, Amir M Abdolahzadeh, Mathieu Nuth and Alexandre R Cabral

Empirical Approaches

to Estimating Hydraulic Conductivity 111 Correlations between Hydraulic Conductivity and Selected Hydrogeological Properties of Rocks 113

Stanisław Żak

Rock Mass Hydraulic Conductivity Estimated by Two Empirical Models 133

Shih-Meng Hsu, Hung-Chieh Lo, Shue-Yeong Chi and Cheng-Yu Ku

Hydraulic Conductivity of Layered Anisotropic Media 159

Stanisław Żak

Laboratory Hydraulic Conductivity Assessment 175 Unsaturated Hydraulic Conductivity

for Evaporation in Heterogeneous Soils 177

Dongmin Sun and Jianting ZhuContents

Determination of Hydraulic Conductivity

of Undisturbed Soil Column: a Measurement Accomplished with the Gamma Ray Transmission Technique 195

Anderson Camargo Moreira, Otávio Portezan Filho,Fábio Henrique de Moraes Cavalcante

and Carlos Roberto Appoloni

Hydraulic Conductivity of Semi-Quasi Stable Soils: Effects of Particulate Mobility 213

Oagile Dikinya

Implications of Hydraulic Conductivity

on Land Management and Policy Development 223 Saturated Hydraulic Conductivity and Land Use Change, New Insights to the Payments for Ecosystem Services Programs:

a Case Study from a Tropical Montane Cloud Forest Watershed in Eastern Central Mexico 225

Alberto Gómez-Tagle (Jr.) Ch., Daniel Geissert, Octavio M Perez-Maqueo, Beatriz E Marin-Castro and M Beatriz Rendon-Lopez

Hydraulic Conductivity and Landfill Construction 249

Witold Stępniewski, Marcin K Widomski and Rainer Horn

This book provides the state of the art of the investigation and the in-depth analysis

of hydraulic conductivity from the theoretical to semi-empirical models to policy velopment associated with management of land resources emanating from drainage-problem soils Many international experts contributed to the development of this book

de-It is envisaged that this thought provoking book of international repute will excite and appeal to academics, researchers and university students who seek to explore the breadth and in-depth knowledge about hydraulic conductivity Investigations into hy-draulic conductivity is important to the understanding of the movement of solutes and water in the terrestrial environment and/or the hydrosphere-biosphere interface Transport of these fl uids has various implications on the ecology and quality of envi-ronment and subsequently sustenance of livelihoods of the increasing world popu-lation In particular, water fl ow in the vadose zone is of fundamental importance to geoscientists, soil scientists, hydrogeologists and hydrologists and is a critical element

in assessing environmental implications of soil management For example, free ter at the soil-atmosphere interface is a source of great importance to man Effi cient management of this water will require greater control of hydraulic conductivity in order to solve such wide ranging problems as upland fl ooding, pollution of surface and ground-waters, and ineffi cient irrigation of agricultural lands

wa-It is generally recognized that progress of science depends increasingly on an advanced understanding diff erences in the methods of investigations and their applicability to solving real problems in the ecological fragile environment In this book a number of approaches were employed in assessing hydraulic conductivity including theoretically and quasi-semi empirical models and conclude with applied policy considerations Of particular importance is the analysis of hydraulic conductivity at the macro-scale to pore scale i.e theoretical conceptions from the geological structures (rock pore space)

to broken rock mass or saprolite (soil-microscopic level) in order to understand the transport phenomena in underground aquifers and porous media in soils Water fl ow and solute transport through soil are directly related to the geometry of the available pore space The role of macroporosity in groundwater movement cannot be overem-phasized, for example, recharging the groundwater by the rapid movement of water through soil macropores may aff ect simultaneous movement of undesirable constitu-ents and resultant rapid contamination of the subsurface water resources This has ac-centuated the need to come up with robust modeling approaches to analyzing the hy-draulic conductivity For instance, in the last two decades, models have been explored

in the fi eld of soil physics to study fl ow processes at the pore scale

While the measurements of hydraulic conductivity is usually tedious and a diffi cult, it

is imperative that diff erent approaches be employed to derive or predict and accurately estimate hydraulic conductivity For this reason, the book is covered in 4 sections in-

cluding: Part 1- Mechanistic and Geotechnical Modelling Approaches; Part 2-Empirical

Mod-eling Approaches to Estimating Hydraulic Conductivity; Part 3- Laboratory Hydraulic tivity Measurements and Part 4- Implications of Hydraulic Conductivity on Land Management and Policy Development.

Conduc-Part 1 explores the robust mechanical and geotechnical theoretical methods to analyse

hydraulic conductivity and includes topics such as i) Infl uence of degree of saturation in the electric resistivity-hydraulic conductivity relationship, ii) Stress/strain-dependent properties of hydraulic conductivity for fractured rocks and Hydraulic conductivity and

water retention curve of highly comprehensible materials iii) On the other hand part 2

covers in-depth analysis of the empirical models to estimating hydraulic conductivity and covered salient topic features including i) Correlations between hydraulic conduc-tivity and selected hydrogeological properties of rocks, ii) Hydraulic Conductivity of layered anisotropic media, and iii) Rock mass hydraulic conductivity estimated by two empirical models Use of measuring techniques and deterministic laboratory hydraulic

conductivity measurements are covered in part 3 and includes topics such as i)

Unsatu-rated hydraulic conductivity for evaporation in heterogeneous soils ii) Determination

of hydraulic conductivity of undisturbed soil column: A measurement accomplished with the Gamma Ray Transmission Technique and iii) Hydraulic conductivity of semi-

quasi stable soils: Eff ects of particulate mobility Part 4 concludes the book with some

applications of hydraulic conductivity implications on land management and policy development and covers interesting topics such as i) Saturated hydraulic conductivity and land use change, new insights to the payments for ecosystem services programs:

a case study from a tropical montane cloud forest watershed in eastern central Mexico and ii) Hydraulic conductivity and landfi ll construction

In conclusion, this book is structured in a way as to overview the state of the art ses of hydraulic conductivity and I hope it will serve the interests of the stakeholders involved in the applications of science of transport of water and solutes to understand-ing the dynamics of fl uids fl ow in porous media In particular the development of poli-cies and strategies pertinent to water availability and management is critical to the im-proved livelihoods of the nations of the world

analy-Thank you

Dr Oagile.Dikinya

Senior Lecturer, University of Botswana,

Botswana

Part 1

Mechanistic and Geotechnical

Modelling Approaches

1

Stress/Strain-Dependent Properties of Hydraulic Conductivity for Fractured Rocks

Yifeng Chen and Chuangbing Zhou

State Key Laboratory of Water Resources and Hydropower Engineering Science, Key Laboratory of Rock Mechanics in Hydraulic Structural Engineering,

in understanding the flow-stress/deformation coupling behavior of a rock system, and their mechanical and hydraulic properties have to be properly established (Jing, 2003)

Traditionally, fluid flow through rock fractures has been described by the cubic law, which follows the assumption that the fractures consist of two smooth parallel plates Real rock fractures, however, have rough walls, variable aperture and asperity areas where the two opposing surfaces of the fracture walls are in contact with each other (Olsson & Barton, 2001) To simplify the problem, a single, average value (or together with its stochastic characteristics) is commonly used to describe the mechanical aperture of an individual fracture A great amount of work (Lomize, 1951; Louis, 1971; Patir & Cheng, 1978; Barton et al., 1985; Zhou & Xiong, 1996) has been done to find an equivalent, smooth wall hydraulic aperture out of the real mechanical aperture such that when Darcy’s law or its modified version is applied, the equivalent smooth fracture yields the same water conducting capacity with its original rough fracture It is worth noting that clear distinction manifests

between the geometrically measured mechanical aperture (denoted by b in the context) and the theoretical smooth wall hydraulic aperture (denoted by b*), and the former is usually larger in magnitude than the latter due to the roughness of and filling materials in rock fractures (Olsson & Barton, 2001)

Developments in Hydraulic Conductivity Research

4

The ubiquity of fractures significantly complicates the flow behaviour in a discontinuous rock mass The primary problem here is how to model the flow system and how to determine its corresponding hydraulic properties for flow analysis Theoretically, the representative

elementary volume (REV) of a rock mass can serve as a criterion for selecting a reasonable hydromechanical model This statement relates to the fact that REV is a fundamental concept

that bridges the micro-macro, discrete-continuous and stochastic-determinate behaviours of the fractured rock mass and reflects the size effect of its hydraulic and mechanical properties

The REV size for the hydraulic or mechanical behaviour is a macroscopic measurement for

which the fractured medium can be seen as a continuum It is defined as the size beyond which the rock mass includes a large enough population of fractures and the properties (such

as hydraulic conductivity tensor and elastic compliance tensor) basically remain the same (Bear, 1972; Min & Jing, 2003; Zhou & Yu, 1999; Wang & Kulatilake, 2002) Owing to high

heterogeneity of fractured rock masses, however, the REV can be very large or in some situations may not exist If the REV does not exist, or is larger than the scale of the flow region

of interest, it is no longer appropriate to use the equivalent continuum approach Instead, the discrete fracture flow approach may be applied to investigate and capture the hydraulic behaviour of the fractured rock masses However, due to the limited available information on fracture geometry and their connectivity, it is not a trivial task to make a detailed flow path model Thus, in practice, the equivalent continuum model is still the primary choice to approximate the hydraulic behaviour of discontinuous rocks

The hydraulic conductivity tensor is a fundamental quantity to characterizing the hydromechanical behaviour of a fractured rock Various techniques have been proposed to quantify the hydraulic conductivity tensor, based on results from field tests, numerical simulations, and back analysis techniques, etc Earlier investigations focused on using field measurements (e.g aquifer pumping test or packer test (Hsieh & Neuman, 1985)) to estimate the three-dimensional hydraulic conductivity tensor This approach, however, is generally time-consuming, expensive and needs well controlled experimental conditions Numerical and analytical methods are also used to estimate the hydraulic properties of complex rock masses due to its flexibility in handling variations of fracture system geometry and ranges of material properties for sensitivity or uncertainty estimations In the literature, both the equivalent continuum approach (Snow, 1969; Long et al., 1982; Oda, 1985; Oda, 1986; Liu et al., 1999; Chen et al., 2007; Zhou et al., 2008) and the discrete approach (Wang & Kulatilake, 2002; Min et al., 2004) are widely applied In this chapter, however, only the equivalent continuum approach is focused for its capability of representing the overall behaviour of fractured rock masses at large scales

Among many others, Snow (1969) developed a mathematical expression for the permeability tensor of a single fracture of arbitrary orientation and aperture and considered that the permeability tensor for a network of such fractures can be formed by adding the respective components of the permeability tensors for each individual fracture Oda (1985, 1986) formulated the permeability tensor of rock masses based on the geometrical statistics

of related fractures Liu et al (1999) proposed an analytical solution that links changes in effective porosity and hydraulic conductivity to the redistribution of stresses and strains in disturbed rock masses Zhou et al (2008) suggested an analytical model to determine the permeability tensor for fractured rock masses based on the superposition principle of liquid dissipation energy Although slight discrepancy exists between the permeability tensor and the hydraulic conductivity tensor (the former is an intrinsic property determined by fracture geometry of the rock mass, while the latter also considers the effects of fluid viscosity and