In order to control the construction risk of karst tunnels

through statistical and theoretical analyses of relevant engineering projects

controlling factors and factors’ weight of water or mud inrush risks of karst tunnels are studied based on analytic hierarchy process; and a three-stage risk assessment and management method is proposed for the evaluation and controlling of construction risk of karst tunnels. Factors’ weight analysis results show that unfavorable geology

geological prediction

formation lithology and groundwater level are the main control ingredients of water or mud inrush risk. Macroscopic geological precursory information

monitoring measurement

contact zones of dissolvable and insoluble rock

geographic and geomorphic conditions

tunnel excavation and supporting are the minor significant factors; microcosmic precursory information

attitude of rock formation

layer and interlayer fissures

surrounding rock mass classification are the least important elements. The three-stage risk assessment method includes preliminary

secondary and dynamic assessment of water or mud inrush risk. Preliminary assessment is the evaluation of risk surroundings (karst hydrogeological and engineering geological conditions)

and it is carried out for the estimation of risk before the enactment of the construction program. Secondary assessment is the evaluation of risk surroundings and risk factors (construction factors)

and it is actualized for the appraisal of construction organization plan pre construction. Dynamic assessment is the evaluation of risk surroundings

risk factors and feedback information of risk management; and it is brought into operation for dynamic risk assessment and management. The three-stage risk evaluation and controlling process can be instantly

effectively

and accurately used for the management of construction risk of karst tunnels

and to realize dynamically amending and governing of risk. The research results are successfully applied to Jigongling Tunnel on the line of Fanba Expressway; and it is of consultant significance for similar engineerings.