Abstract: Malujing tunnel is one of eight Grade I risk tunnels along Yiwan railroad. Large karst rock cavities were developed with high water pressure at DK255+978.  After drainage pipe was drilled through cavities, water and mud inrush happened many times.  Researchers introduced hydrogeology background of Malujing tunnel in this paper.  Hydrogeology monitoring, estimation of peak water inrush and hydrogeology warning technology were also included.

Key words: Karst, Hydrogeology, Estimation of Groundwater Inrush, Warning