Eight typical sites for water immersion tests of collapsibility of loess foundation were determined by combination of the distribution characteristics of loess along the Zhengzhou-Xi'an Passenger Dedicated Line. The test results show as follows: The two water immersion test sites in the section between Zhengzhou and Mianchi exhibit the maximum self-weight collapse settlement of 0. 47 cm to 2. 65 cm, belonging to class Ⅱ of non self-weight collapsible sites; the six water immersion test sites in the section between Mianchi and Xi'an exhibit the maximum self-weight collapse settlement of 10. 4cm to 160. 3 cm, belonging to class II to class IV of self-weight collapsible sites; self-weight collapsibility of loess basically obeys law of gradual strengthening from east to west; for the low-limit depth of self-weight collapsible loess, the values measured at sites are generally less than the calculated values of samples; there is a relationship of the former controlling the latter in sequence with regard to the immersion area, scope of self-weight collapse deformation and range of cracks occurrence. The loess collapsibility of the Zhengzhou-Xi'an Passenger Dedicated Line was evaluated by sections and the foundation treatment depth, the design depth of negative friction of pile foundation and the widths of roadbed waterproof and drainage are recommeded%在分析郑西客运专线黄土分布特征的基础上,选取8个典型工点进行黄土地基湿陷性现场浸水试验.试验结果表明:郑州至渑池段2个试验场地最大自重湿陷量为0.47～2.65 cm,属于Ⅱ级非自重湿陷性场地.渑池至西安段6个浸水试验场地最大自重湿陷量为10.4～160.3 cm,属于Ⅱ级～Ⅳ级自重湿陷性场地,黄土自重湿陷性基本服从自东向西逐渐增强的规律.自重湿陷性黄土下限深度,现场实测值一般小于取样计算值.浸湿范围、自重湿陷变形范围和裂缝发生范围,存在前者控制后者的关系.分段评价郑西客运专线沿线黄土湿陷性,提出地基处理深度、桩基负摩擦力设计深度及路基防排水宽度建议值.
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