A mechanism study on restricting static ice pressure by excavating trench method

In order to prevent and reduce damages of slope lining of reservoirs caused by ice pressure, excavating an ice-breaking trench in an ice cover is a familiar engineering measure. On the basis of field observations about such an ice cover failure in the Hongqipao reservoir, Heilongjiang province, China, and by the use of laboratory tests simulating the ice action, this paper presents the failure process and mechanism of how an ice-breaking trench restricts the maximum static ice pressure by lowering the ultimate failure strength of the ice cover. Study shows that the primary effect of an ice-breaking trench is to develop local deformation of ice cover in bending and then induce its failure by creep buckling. Finally, ice pressure is completely unloaded when ruptured ice cover is fully upheaved. By the use of a simplified static ice pressure model, it has been quantitatively verified that a traditional ice-breaking trench can at least reduce the limit ice pressure in a 1 m-thick ice cover to 60% of its full strength.