Numerical Statical Analysis of Umbrella Drain Performance in Deep Circular Not-lined Tunnel for Steady-State Seepage

In this article, Umbrella drainage system is presented as a alternative drainage system for the tunnels under steady state-seepage condition. The arrangement of this system is inspired from pin-hole drainage system and forepoling method of support installation. In this study, the performance of this drainage system is investigated through numerical statical analysis for deep circular tunnels subjected to steady-state seepage by using ABAQUS finite element software. In this regard, three monitoring parameters have been investigated: tunnel domain’s maximum effective principle strain, pore water pressure distribution of the tunnel walls and hydraulic gradient around the drainages. By taking into account these parameters, an optimum arrangement for the draining system is presented through exploring all of the factors affecting the drainage tube performance.