无砟轨道粗颗粒盐渍土路基设计方法

Design methods of coarse grained saline soil subgrade in ballastless track

我国"一带一路"发展规划中涉及大面积的盐渍土区域,高速铁路线位往往穿越盐质荒漠,沿线不含盐优质路基填料极其匮乏,亟需研究粗颗粒盐渍土作为高速铁路无砟轨道路基填料的可用性。通过技术创新、理论探索,提出了一种无砟轨道粗颗粒盐渍土路基设计方法,内容主要包括采用不同最大粒径、含盐量、溶陷系数及盐胀系数的粗颗粒盐渍土构筑无砟轨道路基,基床底层运用上结构层与下结构层的双结构层进行设计;以基底隔断层、基床隔断层、倒L型防护层、渗水排盐盲沟作为隔盐排盐系统,形成具有堵疏兼备的阻盐、排盐功能;通过容许盐胀变形法对基床底层上结构层、下结构层进行理论计算,确保无砟轨道路基抗隆起变形满足设计要求;对高速列车摩擦力或制动力可能造成基床隔断层复合土工膜产生相对滑移或拉伸破坏,采用最小滑动摩擦系数法进行控制设计。该方法可实现粗颗粒盐渍土在无砟轨道路基领域的首次应用。

A large number of saline soil area is involved in the development program of the Belt and Road Initiatives of China. The alignment of high-speed railway frequently crosses the salty desert, but it is difficult to find the favorable material of subgrade without the salt along alignment. To study the application of coarse grained saline soil in ballastless track subgrade of high-speed railway, a design method of ballastless track of coarse grained saline soil subgrade is derived with technological innovation and theoretical exploration. Different coarse particle size, salinity, subsidence coefficient and salt expansion coefficient of coarse grained saline soil was used to build the ballastless track subgrade. The base bottom layer is designed with the upper structural layer and the lower structural layer. The separation layer of subgrade base and base bed, inverted L- type protective layer, seepage and drainage ditch are used as a system, which are in charge of resistance salt and drainage salt. To ensure the ascension deformation of ballastless track subgrade to meet the design requirements, the deformation of the upper structural layer and the lower structural layer is calculated with the allowing salt expansion method. To avoid the relative slip or tensile damage of the composite geo-membrane in separation layer caused by the friction or braking force of high-speed train, the minimum sliding friction coefficient is adopted to the design. This method realizes the first application of the coarse grained saline soil in the field of ballastless track subgrade.