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APPLICATION OF MODFLOW FOR GROUNDWATER SEEPAGE PROBLEMS IN THE SUBSURFACE TUNNELS (2015)
The construction of subsurface structures such as Tunnel beneath the water table causes the groundwater seepage into the structure and impacts the stability of the structure. A 2.483 km long railway Tunnel was constructed between Katara and Udhampur in Jammu and Kashmir province of India. It is occupied by alluvium with scanty exposures of sandstone belonging to the Middle Shiwalik group. A huge amount of infiltrated water from the perennial canals and agriculture fields is entering the Tunnel. In addition to this, dry Nala/Palaeo channel across the Tunnel alignment contributes significant groundwater seepage during rainy season. A finite difference based groundwater flow model was constructed using the inferences from hydro-geo-morphological features and geologic lineaments to estimate the groundwater seepage and find out the possible solution. The computed flow model indicated that Tunnel would receive groundwater seepage of 78,133 m3 /day. The analysis of the model results revealed that 500 lateral perforated pipes of 5 m in length at an interval of 2 m with an annular space filled with highly permeable geo media can drain out the seepage water. The suggested perforated pipes were successfully installed in the Tunnel. They were effective in draining out the groundwater seepage.
J. Ind. Geophys. Union ( October 2015 ) v.19, no.4, pp:422-432
CSIR-National Geophysical Research Institute (NGRI), Hyderabad