兰新高速铁路沿线盐渍土地基的溶陷特性

Collapsibility Characteristics of Saline Soil Foundation in Lanzhou-Xinjiang High Speed Railway

兰新高速铁路在运营过程中出现了因盐渍土地基溶陷变形导致的线路病害。为此,对沿线不同类型盐渍土地基进行现场浸水载荷试验,并对盐渍土地基的溶陷特性及影响因素进行研究。试验结果表明:不同种类盐渍土地基的整体溶陷量呈现出含石膏粗颗粒盐渍土>细颗粒盐渍土>一般粗颗粒盐渍土的规律,其中粗颗粒盐渍土地基判定为不具有溶陷性。含石膏层粗颗粒盐渍土的溶陷变形主要由附加荷载作用下石膏结晶颗粒遇水软化崩塌造成,溶陷量及溶陷系数均大幅度提高,极值分别可达87.75 mm,0.02,在工程建设中应引起高度重视。骨架颗粒的尺寸效应对地基的承载力及溶陷系数影响显著,在含盐量近似的条件下,粗颗粒盐渍土较细颗粒盐渍土呈现出高地基承载力、低溶陷系数的特征。

There are some railway line diseases caused by saline soil foundation collapsibility and deformation in operation process of Lanzhou-Xinjiang high speed railway.Based on this problem,the field immersion load tests in different saline soil foundations along the railway line were carried out,and the collapsibility characteristics and influencing factors of saline soil foundation were studied.The experimental results show that the total collapsibility volume of different saline soil foundation shows the laws which is the total collapsibility volume of coarse particle saline soil containing gypsum>that of fine particle saline soil>that of general coarse particle saline soil,the coarse particle saline soil foundation is judged to have no collapsibility characteristics,the collapsibility deformation of coarse particle saline soil containing gypsum is mainly caused by the water softening and collapse of the gypsum crystal particles under the additional load,the collapsibility volume and collapsibility coefficient are greatly improved and the extreme values could reach 87.75 mm and 0.02 respectively,which should be paid high attention in engineering construction.The size effect of skeleton particles has a significant influence on the bearing capacity and collapsibility coefficient of foundation,the coarse particle saline soil shows the characteristics of high foundation bearing capacity and low collapsibility coefficient compared with fine particle saline soil under the condition of the approximate salt content.