高速铁路无砟轨道地基泥岩膨胀性分类分级研究

Expansibility classification of mudstone for high-speed railway ballastless track foundation

红层泥岩是一种典型侏罗系沉积岩,其含有微量黏土矿物,易遇水软化、失水崩解,具有一定膨胀性,是引起兰新高速铁路路基持续上拱变形的一个重要因素,故重新判定该种土体膨胀性对高速铁路无砟轨道设计和施工具有重要意义。为此,选取等效蒙脱石含量、阳离子交换量、自由膨胀率和液限为泥岩膨胀性判别指标,通过兰新高速铁路上拱地段大量钻孔实测资料,提出了泥岩膨胀等级分级标准,采用改进层次分析法、基尼系数法和直觉模糊理论确定了判别指标组合权重,基于逼近理想解排序法(TOPSIS法)建立了泥岩膨胀性直觉模糊综合评价模型。结果表明:直觉模糊综合评价模型将泥岩膨胀性进行了定量化,克服了同一试样不同指标属于不同等级判别缺陷;室内膨胀量试验验证了膨胀等级分级标准和直觉模糊综合评价模型对兰新高铁地基泥岩适用性和准确性。研究成果对地基红层泥岩高速铁路路基长期持续上拱变形风险评估和工程控制措施提供技术支撑。

Red mudstone is a typical Jurassic sedimentary rock.It contains trace clay minerals,which is easy to soften in water,disintegrate when dehydrated,and has a certain swelling property.Red mudstone is an important factor that causes the continuous uplift of the subgrade for the Lan-Xin high-speed railway.Therefore,it is of great significance to redefine the expansibility of this kind of soil for the design and construction of ballastless track of high-speed railway.For this reason,the equivalent smectite content,cation exchange capacity,free expansion rate and liquid limit are selected as the indicators of mudstone expansion.The classification criteria for the expansion potential of the mudstone in the foundation are determined through a large number of field testing data.The weight of classification index combination is determined by using improved analytic hierarchy process(AHP),Gini coefficient method and intuitionistic fuzzy theory.The intuitionistic fuzzy comprehensive evaluation model of foundation mudstone swelling property is established based on the technique for order preference by similarity to ideal solution(TOPSIS method).The intuitionistic fuzzy comprehensive evaluation model quantifies mudstone swelling,and overcomes the shortcomings of different indicators of the same sample belonging to different levels.The applicability and accuracy of mudstone classification standard and intuitionistic fuzzy theory evaluation method to Lan-Xin high-speed railway are verified by laboratory expansion tests.The research results provide technical support for the risk assessment and control of long-term continuous uplift of red mudstone foundation for high-speed railway subgrade.