Evaluation and Assessment of Inflow Rates in Tunnels Excavated in Jointed Rock Mass

The effects of key parameters affecting groundwater inflows were investigated using 2-D Distinct Element Method Program which can take into account the coupled hydro-mechanical behavior within the rock fractures. The main concluding points of the study can be summarized as follows: (1) The hydro-mechanical behavior of the ring of tighter rock around the opening is similar to that of a semi-permeable liner, and the rate of water inflow into an unlined rock tunnel taking into account the tighter rock zone can be estimated using an analytical approach similar to that used to calculate inflow into a concrete lined tunnel surrounded by a homogeneous medium. (2) An assessment of the in-situ geology needs to be made to determine the potential of highly pervious features which can have hydraulic conductivities that are orders of magnitude larger than the other discontinuities and cause significant increase of the inflow rate. (3) When the drawdown of groundwater level takes place during tunnel excavation, the inflow rate can be approximately estimated by using the excavation-induced lowered groundwater level above a tunnel instead of the initial groundwater level. (4) Representative value of the jointed rock mass hydraulic conductivity in estimating water flow rate into a tunnel can be obtained from packer test results with applying appropriate adjustment factors corresponding to the depth of excavation, pore pressure values, spacing and nature of the joints likely to be intersected by the opening.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Civil Engineering

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2015

Author dc:creator

• Moon, Joon-Shik

Contributors dc:contributor

• Fernandez, Gabriel

• Engineering, Mining

Language dc:language

eng

Identifier

(MiAaPQ)AAI3269985

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/83329