Significance of Geological Parameters for Predicting Water Inflow in Hard Rock Tunnels

Holmøy, Kristin Hilde; Nilsen, Bjørn

doi:10.1007/s00603-013-0384-9

Cited by 42 publications

(26 citation statements)

References 5 publications

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“…The weathering of fault zones may occur to depths greater than 100 m and effectively seal the fault with clays. For example, in northern Europe, the faults are affected by paleo-weathering (Migo n & Lidmar-Bergstr€ om 2001) and this is thought to cause a reduction of fault permeability to such an extent that the fault conduit may not exist or may not be noticed during tunneling, for example in fjord-crossing subsea tunnels in Norway (Holmøy & Nilsen 2014, Nilsen 2012. Inflow rates are also controlled by boundary conditions and type of surficial materials (Cesano et al 2000) and the depth of tunnel below the water table.…”

Section: Estimating the Proportion Of Faults That Are Conduitsmentioning

confidence: 99%

The biases and trends in fault zone hydrogeology conceptual models: global compilation and categorical data analysis

2016

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To investigate the biases and trends in observations of the permeability structures of fault zones in various geoscience disciplines, we review and compile a database of published studies and reports containing more than 900 references. The global data are categorized, mapped, and described statistically. We use the chi‐square test for the dependency of categorical variables to show that the simplified fault permeability structure (barrier, conduit, barrier–conduit) depends on the observation method, geoscience discipline, and lithology. In the crystalline rocks, the in situ test methods (boreholes or tunnels) favor the detection of permeable fault conduits, in contrast to the outcrop‐based measurements that favor a combined barrier–conduit conceptual models. These differences also occur, to a lesser extent, in sedimentary rocks. We provide an estimate of the occurrence of fault conduits and barriers in the brittle crust. Faults behave as conduits at 70% of sites, regardless of their barrier behavior that may also occur. Faults behave as barriers at at least 50% of the sites, in addition to often being conduits. Our review of published data from long tunnels suggests that in crystalline rocks, 40–80% (median about 60%) of faults are highly permeable conduits, and 30–70% in sedimentary rocks. The trends with depth are not clear, but there are less fault conduits counted in tunnels at the shallowest depths. The barrier hydraulic behavior of faults is more uncertain and difficult to observe than the conduit.

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Section: Estimating the Proportion Of Faults That Are Conduitsmentioning

confidence: 99%

The biases and trends in fault zone hydrogeology conceptual models: global compilation and categorical data analysis

2016

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“…Here, conductivity accounts for the characteristics of the infilling material, and joint roughness and aperture are related to flow modes, and thus affects the conductivity. Holmøy (2008) described also groundwater flow into hard rock environments being dependent on discontinuities such as joints and their permeability.…”

Section: Considerations Of Hydrogeological Factorsmentioning

confidence: 99%

“…Regarding stress distribution, most water bearing structures are usually oriented subparallel to the highest principal stress orientation (Selmer-Olsen, 1971;Holmøy, 2008). A report from the mining company from 1979 shows two locations where stress measurement was carried out and it was reported that the major principal stress was found to be of 6.8MPa and 4.4MPa, respectively.…”

Section: Hydraulic Conductivity Assessmentmentioning

confidence: 99%

Assessment on the hydrogeological condition of an open pit mine based on piezometric measurements

et al. 2021

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Understanding groundwater and flow pattern behavior in a given mine site is generally based on accepted theory related to flow through porous granular media. The existence of discontinuities within the rock mass alters the accepted hydraulic behavior being the joint profile and aperture variability a challenge when designing an open pit mine. In this regard, groundwater interaction with the rock mass is the key variable that influences mining slope design and monitoring. This manuscript studies and analyses the geotechnical perspective of an open pit mine and carries out a comprehensive assessment on the groundwater behavior of an open pit mine in a hard rock environment. The analysis is carried out using data gathered from piezometers and correlating the findings with the structural model of the mine. A comparison of the analysis with the results of previous investigations like hydraulic testing and mapping of the mine site are presented comprehensively. The authors propose the concept of receding time for a better understanding of the drainage capability of a given discontinuity (or a set of them) and its importance in assessing groundwater behavior of the pit slope. Discussions are also made on how groundwater flow can be locally modified by slope scale structures and what are the potential consequences there may have for overall slope stability.

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“…1), and is part of the Rv 35 between Lunner and the Gardermoen Airport. The tunnel breakthrough was achieved in October 2002, it is 3.8 km long, has a 62-m 2 (T9)-profile, and the rock cover varies from 20 to 230 m. Due to environmental reasons, sections of the tunnel had water inflow criteria as low as 4 to 20 l/min per 100-m tunnel (Holmøy 2008). During the tunnel excavation, high levels of water leakage were encountered.…”

Section: Defining the Interpretation Modelmentioning

confidence: 99%

Resistivity mapping as a tool for identification and characterisation of weakness zones in crystalline bedrock: definition and testing of an interpretational model

Rønning

Ganerød

Dalsegg

et al. 2013

Bull Eng Geol Environ

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In recent years, the focus on feasibility studies for tunnels has increased in Norway. Traditionally, the refraction seismic method and the very low-frequency electromagnetic method (VLF-EM) have been used. The Geological Survey of Norway introduced the electrical resistivity traversing method (ERT) in feasibility studies for tunnel construction purposes. Resistivity modelling shows that the method has the potential to characterise fracture zones geometrically; i.e., the thickness, dip, and depth extent. Based on previous studies, a model for mineralogical characterisation is proposed. This model, and the possibility for geometrical characterisation, is critically tested with success on three tunnel projects. The results of the comparison study, with regards to weakness zones, show that VLF-EM is a method that is capable of locating fracture zones, while refraction seismic is capable of locating and indicating the width of the zone, and can be used to imply the thickness of the soil cover above bedrock. The 2D resistivity method is able to locate the weakness zone, indicate the width, depth extent, and the dip of the zone, and in addition, characterise the zone with respect to stability or water problems. The crystalline bedrock characterisation is divided into three groups: resistivity values above 3,000 X m indicating good rock quality, values between 3,000 and 500 X m indicating bedrock with mainly water problems, while values \500 X m indicate clay-bearing, unstable rock with fewer water problems. From our investigations, we conclude that the 2D resistivity method is a very good supplement to traditional methods for feasibility studies on tunnelling purposes in crystalline rock.

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Significance of Geological Parameters for Predicting Water Inflow in Hard Rock Tunnels

Cited by 42 publications

References 5 publications

The biases and trends in fault zone hydrogeology conceptual models: global compilation and categorical data analysis

The biases and trends in fault zone hydrogeology conceptual models: global compilation and categorical data analysis

Assessment on the hydrogeological condition of an open pit mine based on piezometric measurements

Resistivity mapping as a tool for identification and characterisation of weakness zones in crystalline bedrock: definition and testing of an interpretational model

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