REHABILITATION OF MULTIPLE TUNNELS USING FILTER

Document Type : Original Article

Authors

1 Assoc. Prof., Water and Water Structures Eng. Dept., Faculty of Eng., Zagazig University, Zagazig, Egypt.

2 Prof. of Water Structures, Head of Water and Water Structures Eng. Dept., Faculty of Eng., Zagazig University, Zagazig, Egypt.

3 Assistant Lecturer, Water and Water Structures Eng. Dept., Faculty of Eng., Zagazig University, Zagazig, Egypt.

Abstract

Rehabilitation of old tunnels can be achieved through reduction of
seepage forces on them using filters. In this case, the potential head on the outer
surface of the tunnel can be reduced to reach zero. Circular tunnel rounded by
filter known as (drainage-type tunnel) that permits flow through the filter around
the tunnel. The special purpose computer program (Z-soil) is used to study
seepage flow around single, double and triple tunnels rehabilitated by filters in
homogeneous isotropic and anisotropic soils with different anisotropy ratio. The
study includes the effect of the relative groundwater level, relative depth of the
impermeable layer, relative depth of the tunnel under ground surface, and soil
anisotropy ratio on the average seepage pressure around the tunnels. All the
relations are presented in the form of dimensionless curves. The reduction in
seepage pressure around single, double and triple tunnels resulting from the
existence of filter are obtained.

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