兰州地铁大厚度湿陷性黄土地层的现场浸水试验研究

为了研究大厚度湿陷性黄土地层的湿陷性对城市轨道交通地下结构的影响，针对传统室内试验评价结果不准确的缺点，依托兰州地铁3号线一期工程—陡道沟站，选取典型大厚度湿陷性黄土施工场地，通过开展场地地面浸水试验，测试了地面入渗过程中不同深度地层的湿陷沉降变形及地表的沉降变形，研究了既有黄土地层的湿陷变形特性，并结合室内试验的结果进行验证。结果表明：①场地内黄土的湿陷性具有突发性的特点，地表土层及深部土层的湿陷变形大体呈现陡增、骤降和平稳三个阶段；②场地内黄土的湿陷系数随着黄土深度的增加而降低，自重湿陷系数与深度的关系曲线符合幂函数关系，相关性为0.983；③兰州地区湿陷性黄土地层自重湿陷变形计算值的修正系数建议取值为1.675。研究结果可为兰州地区大厚度湿陷性黄土地层地铁设计及施工提供借鉴。

Immersion tests on self-weight collapsible loess site with #br# large depth of Lanzhou metro line

 In order to study the influence of collapsibility of large thickness collapsible loess stratum on the underground structure of urban rail transit, aiming at the shortcomings of inaccuracy of traditional indoor test evaluation results, selects typical large thickness collapsible loess construction site based on DOUDAOGOU station of the first phase project of Lanzhou Metro Line 3, and tests the different depths of the ground infiltration process through the ground water immersion test. In this paper, the collapsible deformation characteristics of the existing loess stratum are studied and verified by the results of laboratory tests. The results show that: ① the collapsibility of loess in the site is sudden, and the collapsibility deformation of surface soil layer and deep soil layer generally presents three stages: steep increase, sudden drop and stable; ② the collapsibility coefficient of loess in the site decreases with the increase of loess depth, and the relation curve between the self weight collapsibility coefficient and depth conforms to the power function, with the correlation of 0.983; ③ The correction coefficient of self weight collapsible deformation of collapsible loess stratum is suggested to be 1.675 in Lanzhou area. The research results can be used for reference in the design and construction of Metro in Lanzhou area.