1 Introduction to Water Circulation in Rocks ................... 1
1.1 General Observations .................................... 1
1.2 Origin of Discontinuities ............................... 2
1.3 Features of Discontinuities ............................. 3
1.3.1 Orientation ...................................... 4
1.3.2 Degree of Fracturing ............................. 6
1.3.3 Persistence ...................................... 8
1.3.4 Aperture and Filling ............................. 9
1.3.5 Roughness ....................................... 10
1.3.6 Weathering ...................................... 12
1.3.7 Moisture Conditions and Seepage ................. 12
1.4 Graphical Representation of Discontinuities ............ 13
1.4.1 Equal Areal Projections ......................... 14
1.4.2 Equal Angle Projections ......................... 16
1.5 Basic Elements for Hydrogeological Conceptual Model
Definition ............................................. 19
1.5.1 The Work Scale .................................. 21
1.5.2 Elementary Representative Volume ................ 22
1.5.3 Changing of Fracturing Degree with Depth ........ 23
1.6 Probabilistic Generation of Discontinuity Network ...... 24
2 Hydraulic Conductivity Assessment ........................... 29
2.1 Introduction ........................................... 29
2.2 Deterministic Methodologies ............................ 29
2.2.1 Hydraulic Conductivity Along a Single
Fracture ........................................ 29
2.2.2 Hydraulic Conductivity Along a Fracture
System .......................................... 32
2.2.3 Hydraulic Conductivity Tensor ................... 33
2.2.4 Equivalent Hydraulic Conductivity ............... 35
2.3 Probabilistic Methodologies: Percolation Theory ........ 36
2.4 In Situ Tests .......................................... 41
2.4.1 Lugeon Tests .................................... 41
2.4.2 Hydrogeochemical Methods ........................ 42
2.4.3 Hydraulic Tests in Double-Porosity Aquifers ..... 44
2.4.4 Hydraulic Tests in Anisotropic Aquifers ......... 46
3 Influence of Joint Features on Rock Mass Hydraulic
Conductivity ................................................ 49
3.1 Introduction ........................................... 49
3.2 Influence of Joint Roughness ........................... 49
3.2.1 Effects of Roughness on Hydraulic Conductivity
of a Single Joint: Theoretical Analysis ......... 50
3.2.2 Effects of Roughness on Hydraulic Conductivity
of a Single Joint: Experimental Checking ........ 53
3.2.3 Effects of Roughness on Rock Mass Hydraulic
Conductivity .................................... 56
3.3 Influence of Joint Aperture ............................ 58
3.3.1 Changes in Aperture with Depth .................. 59
3.3.2 Changes in Aperture with the Stress Field ....... 63
3.4 Influence of Joint Spacing and Frequency ............... 67
3.5 Joints Interconnection ................................. 69
4 Main Flow Direction in Rock Masses .......................... 73
4.1 Introduction ........................................... 73
4.2 Anisotropy of the Fractured Medium ..................... 73
4.3 Main Flow Direction in Fractured Media ................. 76
4.4 Non-saturated Medium ................................... 77
4.5 Non-saturated Medium: Main Flow Direction with
an Impermeable Layer.................................... 81
4.6 Saturated Medium ....................................... 82
4.6.1 Known Hydraulic Gradient ........................ 83
4.6.2 Unknown Hydraulic Gradient ...................... 84
5 Methods and Models to Simulate the Groundwater Flow in
Rock Masses ................................................. 87
5.1 Introduction ........................................... 87
5.2 Basic Elements of a Modeling Approach .................. 87
5.2.1 Definition of the Conceptual Model .............. 89
5.2.2 The Model Project ............................... 90
5.2.3 Choice of the Numerical Code .................... 90
5.3 Darcy's Model .......................................... 91
5.4 Discrete Models ........................................ 93
5.5 Dual Porosity Models ................................... 97
6 Case Histories ............................................. 101
6.1 Groundwater Flow and Slope Stability .................. 101
6.2 Evaluation of the Hydrogeological Risk
Linked with Tunneling ................................. 108
6.2.1 Reconstruction of the Groundwater Flow ......... 110
6.2.2 Estimation of the Tunnel Inflow ................ 111
6.2.3 Delimitation of the Tunnel Influence Zone ...... 116
6.2.4 Hydrogeological Risk Analysis .................. 123
6.3 Hydrogeological Risk Linked with Road Construction .... 127
6.4 Mountain Aquifer Exploitation and Safeguard:
Eva Verda Basin Case Study
Saint Marcel, Aosta Valley, Italy) .................... 135
6.4.1 Hydrogeological Reconstruction .................. 138
6.5 Stochastic Groundwater Modeling for the Drying
Risk Assessment ....................................... 144
6.5.1 Hydrogeological Setting of the Study Area ...... 145
6.5.2 Groundwater Model of the Nossana Spring ........ 147
6.5.3 Factors Involved in the Depletion Curve ........ 151
6.5.4 Drying Risk Assessment ......................... 153
References .................................................... 155
Index ......................................................... 163
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