Research purposes:Based on the engineering analogy and numerical analysis, the method is offered for determining the minimum security coping thickness of sub-aqueous tunnel for offering the reference to the similar works.
Research conclusions:(1) The Norwegian Experience Curve Method is the simple stand the most easy and it is suitable for the primary determination at the early stage of geological survey while the construction period is pressed, but its result is conservative and needs to be economically verified at later stage. (2) The Water-resisting Rock Column Experience Formula can accurately determine the minimum security coping thickness and its result can be as the reference after the geological condition is well known. (3) The result obtained with numerical analysis is the most accurate, but the numerical analysis needs lots of certain conditions. Only when the external conditions, such as working condition, engineering geological condition and hydrogeologic condition, are determined can establish the model for returning the original construction condition, so its result can be as the reference to the final determination.