季冻区桥梁基桩抗冻拔验算几个问题的探讨

Approach to Some Problems of the Check of Anti-Frost Heaving of Bridge Pile Foundation in Seasonally Frozen Regions

Based on investigations and practical project experiments, some new ideas on the check of anti-frost heaving of bridge foundation piles are proposed and their principal contents have been admitted into the new revised edition of the Design Code of the Base and Foundation of Highway Bridge and Culvert.The values of the tangential frost heaving force on bridge structure presented in this paper are based on the hydrogeologic characteristics of the bridge structure and determined according to the envelope of the actual values measured recently in our country.The frost depth is variable, so that the standard frost depth should be taken in design. When calculating tangential frost heaving force, it is suggested that a revised coefficient nTof the standard frost depth should be used.According to the stress state of a pile under the action of frost heave, it is pointed out that the value of friction between the pile and warm earth determined on the basis of a general axial tensile pile is wrong . It should be determined on basis of a general axial compressed pile.On the basis of actual test conditions under which the value of friction between pileand soil is determined, only half of the pile weight below freezing front should be considered.