Scipedia: Dam Engineering & Hydroelectric Energy

Geomechanical Behaviour of Fault Zones During Tunnel Excavation: Critically-Stressed Fault Analysis, In-Situ Stress Assessment, and the FZSEI Framework

Alessandro Calvi — Sun, 13 Sep 2026 08:16:03 +0200

Fault zones represent the most challenging geological discontinuities encountered during road and railway tunnel construction. When tunnel excavation intersects active or reactivated faults, the in-situ stress state within the rock mass undergoes profound perturbations: the fault core and damage zone display sharply contrasting mechanical and hydraulic properties compared with intact host rock, preferential slip planes exist at critically stressed orientations, and elevated pore pressures may transiently destabilise the excavation face. Conventional tunnel design methods, which treat the rock mass as a homogeneous elastic medium, systematically underestimate the support requirements and the risk of sudden failure events — including face collapse, large-displacement squeezing, and rockburst — in these settings. This article presents a rigorous geomechanical analysis of fault zone behaviour during tunnel excavation, grounded in the critically-stressed fault theory of Zoback (2010) and in the extensive body of evidence from deep borehole studies, seismic reflection surveys, and fault zone hydraulics. The Mohr-circle framework for evaluating fault criticality, the Stress Criticality Index (SCI) quantifying the proximity of a fault to frictional reactivation, the fracture density powerlaw model governing damage zone architecture, and the permeability-stress coupling equations are all translated into tools applicable to the tunnel design workflow. On this basis, the article proposes a new predictive framework — the Fault Zone Stress-Excavation Interaction (FZSEI) framework — that integrates SCI computation, damage zone geometry characterisation, pore-pressure transient modelling, and adaptive support classification into a unified design methodology

Application of the ISAF-RT Integrated Stress Analysis Framework to the Gorges du Verdon (Southwestern French Alps): In-Situ Stress State, Tunnel Geomechanics, and Comparative Evaluation with Barton's Q- System

Alessandro Calvi — Sun, 13 Sep 2026 08:08:23 +0200

The Gorges du Verdon (Haute-Provence, SW French Alps) constitute a spectacular deep fluvial canyon incised into Upper Jurassic to Lower Cretaceous Tithonian limestones of the Castellane fold-and-thrust belt, a region characterised by active thin-skinned compression (~0.1 mm/yr uplift), a complex network of N–S and E–W fault systems, and topographic relief of 300–700 m. Recent cosmogenic ³⁶Cl exposure dating by Cardinal et al. (2024) has quantified river incision rates of 0.06–0.20 mm/yr for the Late Pleistocene (60–15 ka), with a marked acceleration to 0.90

Alessandro Calvi — Sun, 23 Nov 2025 09:32:34 +0100

Alessandro Calvi — Sun, 23 Nov 2025 09:31:53 +0100

Alessandro Calvi — Sun, 23 Nov 2025 09:33:17 +0100

Alessandro Calvi — Sun, 23 Nov 2025 09:33:43 +0100

Alessandro Calvi — Sun, 23 Nov 2025 09:35:07 +0100

Alessandro Calvi — Sun, 23 Nov 2025 09:35:23 +0100

Alessandro Calvi — Sun, 23 Nov 2025 09:35:41 +0100

Fondazioni profonde di dighe, ture e diaframmi

Alessandro Calvi — Sun, 23 Nov 2025 09:42:43 +0100

DE LA RESPONSABILITÉ DES ENTREPRENEURS ET DES INGÉNIEURS-ARCHITECTES EN MATIÈRE DE CONSTRUCTION D'USINES, DE BARRAGES ET D'INSTALLATIONS

Alessandro Calvi — Sat, 22 Nov 2025 21:22:34 +0100

Les nouveaux groupes de la centrale prototype de Castet

Alessandro Calvi — Sat, 22 Nov 2025 21:04:33 +0100

Technical Due Diligence Report – Anderson Dam & Hydropower Plant (California, USA)

Alessandro Calvi — Sat, 22 Nov 2025 19:50:23 +0100

This study represents the technical due diligence of the hydroelectric plant consisting of the
Anderson Dam (Leroy Anderson) and its power station, located in California, USA.
This technical contribution is structured analyzing the hydrogeological aspects of the dam site's
geographical context, including its structural behavior in the event of significant seismic events, and
then going more in detail on the energy assessments that take into account the temporal distribution
of rainfall and flow rates, as well as the efficiency of the hydraulic machinery installed.

Statistical and Probabilistic Parameters Used as Reference for Hydrological-Energy Studies

Alessandro Calvi — Sat, 22 Feb 2025 00:11:04 +0100

Hydropower plant future production estimation is based on hydrological-hydraulic data. The present metholodogy validates the median as the reference parameter to be used for a better interpretation of statistical series, because it is a centered value where duration curves and their complementary curves intersect. Then, it is not affected by extreme events, providing a well representation of the whole dataset.

Geomechanical Challenges and Engineering Solutions for Tunnel Stability in the Himalayas: A Case Study Approach

Alessandro Calvi — Sun, 09 Feb 2025 22:30:03 +0100

The Himalayan region, characterized by complex geological formations and high tectonic activity, presents significant challenges for tunnel construction. This paper examines geomechanical issues such as tunnel squeezing, stress-induced instability, and rock bursting, with a focus on hydropower and railway tunnel projects in Nepal and India. Case studies, including the Chameliya Hydroelectric Project, Parbati II Hydroelectric Project, Nilgirikhola Hydroelectric Project, and railway tunnels in the Garhwal Himalaya, highlight the impact of weak, schistose rock masses and extreme overburden pressures. Various engineering methodologies, including empirical, semianalytical, analytical, and numerical modeling approaches, are discussed to assess stress states and deformation behavior. The study underscores the need for adaptive excavation techniques, such as the New Austrian Tunneling Method (NATM) and rock mass classification systems, to ensure tunnel stability. By integrating probabilistic analysis and advanced support systems, this research contributes to optimizing underground construction strategies in geologically challenging terrains.

THOUGHT LEADERSHIP IN HYDROPOWER & DAMS: A CASE STUDY

Alessandro Calvi — Mon, 03 Feb 2025 18:37:03 +0100

The presented paper is aimed to the analysis of a case study in the hydroelectric sector, evaluating the achievement of “Thought Leadership”.

Italian Dams Bibliography

Alessandro Calvi — Sun, 21 Apr 2024 19:03:12 +0200

RASSEGNA BIBLIOGRAFICA DELLA LETTERATURA ITALIANA SULLE DIGHE DI RITENUTA

EURCOLD - Dam Legislation

Alessandro Calvi — Sat, 20 Apr 2024 20:26:10 +0200

ROBUSTNESS AND CONSEQUENCE BASED ASSESSMENT OF AN EXISTING DAM

Alessandro Calvi — Tue, 16 Apr 2024 10:34:02 +0200

Robustness plays a relevant role in the capacity of a structure to sustain abnormal loads
or to deal with unexpected events with large effects, such as explosions and terroristic
attacks. Such situations on dams may have extremely large consequences. For buildings,
the design approach that best implements robustness concepts is represented by the so
called “Consequence Based Design”: even if nothing is known about the cause, selective
element removals and extreme load on the structure are modeled, and their effects are
determined with respect to progressive collapse and damage arrest.
In the paper we try to set-up a “Consequence Based Assessment” of a typical example of
a gravity dam built between the ‘30s and ‘40s of the last century in the northwestern
Italian Alps. A simplified model of the structure is adopted. Removal of parts of the dam
cross-section is assumed to occur: the effects of the extent of damage is discussed on the
bases of the tension generated within the body of the dam.