铁路路基承载力设计方法的探讨

Exploration on the Design Method of Bearing Capacity of Railway Subgrade

研究目的:《铁路路基设计规范》对路基基床范围内的天然地基承载力采用统一标准,该标准只与铁路等级有关,而与上部荷载及边界条件无关,这与地基承载力的基本定义存在矛盾。基底为软弱地基的低矮路堤,采用复合地基加固时,为满足规范对于地基承载力的要求,必须采用较小的桩间距,此时沉降、稳定已经存在较大富余量,造成很大浪费,给设计者带来很大的困扰。针对上述问题,本文以单线铁路路基为例,探讨全新的铁路路基承载力设计方法。研究结论:(1)铁路路基基床范围内的天然地基承载力要求不宜采用统一标准,宜根据上部荷载及边界条件计算确定;(2)路基基底压应力可根据上部荷载采用常规的地基力学模型计算确定,天然地基承载力应根据边界条件进行修正,路基基底压应力小于或等于修正后的天然地基承载力即为满足设计要求;(3)本文探讨的设计方法理论依据充分,计算原理简单,设计结果合理,可有效地避免工程浪费,可以为铁路路基设计方法的改进和完善提供一定的借鉴作用。

Research purposes： The requirements of natural foundation bearing capacity of roadbed adopt the unified standard according to Code for Design 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 low embankment 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 this 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 the above problems, this paper discusses the design method of the 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 the 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.