Engineering risk management of mountain tunnels based on observation

The concept of risk crosses through the society with significance and value that differ greatly in space and time. Mountain tunnel engineering has high risk because of plenty of uncertainties in many of areas related to ground conditions. The uncertainties have characteristics such as complicated geology environment, insufficient basic data and multiple construction methods. Risk management and control, which is effective to reduce risk of mountain tunnel engineering, can be implemented during the construction of mountain tunnel engineering. The residual risk management and control of construction phase can be solved with observation. The case of Huangtian tunnel of Huangshan-Quzhou-Nanping Expressway of Zhejiang Province is taken as an example. A risk management frame, composed of risk management matrix, daily risk report on the basis of observation data and risk warning system, is established according to the potential damage and probability of harmful cases. The risk management frame proves to be effective in dealing with the risk management during the construction phase of Hunagtian tunnel through the instrumentality of field investigation and crown displacement of YK17+660, which is at the right exit end of Huangtian tunnel, and can provide the basis and ideas for similar projects. Moreover, it is concluded that the establishment of the acceptable risk criterion of mountain tunnel engineering should be based on the allowable deformation limits and the reaction time of surrounding rock of tunnels.