Abstract：With the allowable maximum ground settlement as target value，a dynamic optimization model is designed to draw up the strategy(technical measures) controlling the effect of tunnelling on environment. Through adjusting the project during the stages of design and construction，the model distributes the risk of effect on environment to each step of construction reasonably and keeps the technical measures of each step with clear environmental control object. If there is deviation between practical situation and forecast，the model can adjust the technical measures of the subsequent steps and repeat like this until the construction is over. So the model can effectively control the effect of tunnelling on environment. At the same time the rule of the limitation of target value is also studied.
