Water inrush is one of the typical geological hazards during tunnel construction in karst area; an attribute recognition model of water inrush risk evaluation is established based on attribute mathematic theory in order to control the water inrush risk and guarantee tunnel construction’s safety. Firstly

formation lithology

unfavorable geology

groundwater level

topography and geomorphology

contact zone of dissolvable and insoluble rocks

layer and interlayer fissures are selected as first grade indices of attribute recognition by considering of karst hydrologic and engineering geological conditions; and the unfavorable geology is divided into water-bearing structure

karst water system and fault fracture zone as second grade indices. The weights of first grade indices are determined by frequency statistic method through collecting and collating information of typical water inrush examples of karst tunnels; and the weights of second grade indices are determined by judgment matrix established by analytic hierarchy process (AHP). Then attribute measurement functions are rigorously constructed to compute attribute measurement of single index and synthetic attribute measurement. Lately

the identification and classification of risk assessment of water inrush in tunnels are recognized by the confidence criterion. The water inrush risk of Jigongling tunnel on the line of Fanba expressway is evaluated based on the established attribute recognition model; and the evaluation result agrees well with construction situation

so as to provide an effective method for water inrush risk evaluation of karst tunnels.