Abstract：Abstract ； Research purposes ： The requirements of natural foundation bearing capacity of roadbed adopt the unified standard according to Code for Desi^*n on Subgrade of Railway. The standard is only related with the level of railway， and has nothing to do with the upper load and boundary conditions. When the foundation of the lowembankment is soft and strengthened by composite foundation， in order to meet the requirements of the standard for foundation bearing capacity，we must use a small pile spacing. At tliis time，there is a large amount of settlement and stability. It is great waste to the project and the designers are very troubled. In view of tlie above problems，this paper discusses the design metliod of tlie new railway subgrade bearing capacity based on the example of single line railway subgrade. Research conclusions;(1 ) The requirements of natural foundation bearing capacity of roadbed should not adopt the unified standard，it is accepted that tiie bearing capacity is determined by calculation according to the upper load and boundary conditions. (2 ) Subgrade basal stress can be calculated and determined by conventional foundation mechanics model according to the upper load. The natural foundation bearing capacity can be modified according to the boundary conditions. When the subgrade basal stress is less than or equal to the modified foundation bearing capacity，that is to meet the design requirements. (3) The design method this paper discusses can effectively avoid waste and provide the reference for the improvement and perfection of railway subgrade design method.
2017, Vol. 34 
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