Details

Autor(en) / Beteiligte

• Cesano, Daniele

Titel

Water leakage into underground construction in fractured rocks: Geological and hydrogeological information as a basis for prediction

Ort / Verlag

ProQuest Dissertations & Theses

Erscheinungsjahr

2001

Quelle

ProQuest Dissertations & Theses A&I

Beschreibungen/Notizen

• The main objectives of this thesis are (a) to identify the importance of geological and hydrogeological factors in regulating water leakage into underground constructions, and (b) to investigate the usability of different types of geological and hydrogeological information in relation to the leakage, and (c) to provide a more quantitative definition of “heterogeneity” to see how this changes with scale and its connection to predictions. To achieve these objectives, studies were made at the two water-transportation tunnels, Bolmen in southern Sweden, and Pont-Ventoux in northern Italy, and at the proposed US high-level nuclear waste repository at Yucca Mountain in southern Nevada. Statistical methods such as correlation analysis, analysis of variance and linear regression analysis have been used for the identification of the geological and hydrogeological factors, while a heterogeneity index (Ih) has been developed to quantify the fracture heterogeneity of hard-rock environments. An unsaturated flow model, the enhanced Wang and Narasimhan model (EWNM), has been developed to estimate dripping initiation times into the Yucca Mountain Exploratory Studies Facility. At the Bolmen Tunnel, the observed leakage was shown to be regulated not only by factors in the rock mass but also by factors in the unconsolidated deposits. At the Pont-Ventoux Tunnel, Ih has been shown to be suitable for quantifying the overall fracture heterogeneity on different scales. There is evidence that the highest amount of leakage seems to come from those areas where Ih is the lowest. The differences between using different fracture-collection methods for describing the heterogeneity was also demonstrated through the index. The EWNM has been able to reproduce the dripping initiation times at Yucca Mountain Exploratory Study Facility tunnel according to what has been found using 36Cl analyses. However, the model describes a complex process of unsaturated fracture flow, and future research is still needed to find methods suitable for independent estimations of parameters, as these values are difficult to measure in the field.