南百段膨胀土路基病害概况及防治措施

Subgrade Disease Treatment for Expansive Soil on Nanning-Baise Railway Line

膨胀土地区的路基基床经常出现路基变形、翻浆冒泥、道渣基床土挤出等病害问题。目前,对于膨胀土基床病害的治理主要采用传统方法从设计和施工方面降低膨胀土干缩湿胀带来的不利影响。施工中路基封闭宽度不足、换填深度不够以及换填改性土质量差等问题是采用传统方法整治达不到预期效果的主要因素。通过对南昆铁路线南百段沿线的气候、水文气候条件、膨胀土特性、列车荷载影响等方面的分析,探讨了膨胀土地区铁路路基基床病害的原因,并在整治中使用粉煤灰石灰黏土制作了改性土分层碾压,用地蜂窝固砂,加大土层封闭宽度,侧沟下新修盲沟排水以及在强膨胀土路段用石灰桩处理下沉路基的方法,效果显著,可为同类工程提供借鉴。

Diseases such as subgrade deformation,mud pumping and lag soil extrusion can be seen in roadbed in the expansive soil area. Currently,traditional methods of design and construction are adopted to reduce the bad effect of material shrinkage and bulking effects brought about by expansive soil. The major reasons of not having met desired effect can be attributed to insufficient subgrade width and replacement depth,and lowquality of replacement soil. Based on analysis of climate,hydrology,expansive soil characteristics and train load along the Nanning-Baise railway line,causes of subgrade diseases of expansive soil have been proposed. Treatment like applying fly ash lime clay to make modified soil for layered rolling,reinforcing sand by geocell,broadening subgrade width,building additional drainage belowside ditch and treat sunken subgrade by building lime pile along the strong expansive soil section have been proved to be effective and can be applied to similar projects.