铁路高填土涵洞的设计方法

Design Method of High Earth Fill Culvert in Railway

目前的铁路涵洞通用图适用于跨度≤3m且填土高≤20m和3m≤跨度≤6m且填土高≤16m的涵洞,超出上述范围的高填土涵洞需进行特殊设计。文章结合国内有关资料,介绍了铁路高填土涵洞的设计原则,提出了涵洞土压力的计算方法和基底应力计算方法,并采用典型工程实例进行了验证。研究结果表明:(1)采用非线性土压力计算公式计算高填土涵洞,能反映高填土条件下,涵洞顶部土压力的变化过程,计算方法经济合理。(2)一般情况下,无需单独计算高填土涵洞基底应力,但对于承载力不高的软质岩地层或者冻土地层,建议进行计算,以核查是否满足规范要求。(3)涵洞基础应尽量设于高承载力土层或加固处理后的地基之上,以降低沉降。(4)高填土涵洞受活载影响非常小,盖板、墙身可不考虑活载内力,基底应力计算可不考虑弯矩。

The standard drawing of railway culvert is applicable to the following two cases;the span is less than or equal to 3 m and less than 20 m high embankment;the span is greater than or equal to 3 m and less than or equal to 6 m and less than 16 m high embankment.For the high fill culvert beyond the above range,special design is needed.Combined with relevant domestic information,the design principle of high fill culvjert in railway is introduced,the calculation method of soil pressure and the calculation method of base stress are put forward,and the two engineering examples are used to verify that.The results of tire study show that;(1)The calculation formula of high fill culvert using nonlinear soil pressure can reflect the change process of soil pressure at the top of culvert under the condition of high fill,and the high fill culvert with this formula is more economical and reasonable.(2)The base stress of high fill culverts is generally not required to be calculated alone,but for soft rook or frozen soil layer with low bearing capacity,it is suggested to be calculated to verify whether the requirements are met.(3)In order to reduce settlement,culvert foundation should be placed on high bearing capacity soil layer or on the reinforced foundation.(4)The influence of live load on culvert of high filled culvert is very small.The internal force of live load can not be considered in the cover and wall body.The bending moment is not considered in the calculation of base stress.