Abstract:

The Zhengzhou-Xi'an passenger dedicated line allows 15 mm settlement of embankment after acceptance. The settlement control of ground treatment in collapsible loess is a key technical problem. Therefore, the settlement of an embankment construction on ground treatment with different measures is observed and researched experimentally in a selected area of typical collapsible loess. The results show that the compression settlement of embankment body is only 3 mm and have already stabilized in 15 days after completion of embankment. The embankment settlement is primarily controlled by the foundation settlement which is determined by the settlement of soils below three different kinds of ground treatment layer. A section of pile thrusted-expanded in column-hammer which treats all 22 m depth of collapsible loess is best, a section of cement soil pile which treats 15 m depth of collapsible loess is better, a section of dynamic compaction which treats 6 m depth of collapsible loess is worst in the settlement, ground treatment and immersion effect. It is very essential that the reasonable waterproof and drainage measures are taken to prevent water from immersing the vicinity of slope foot. The average value of results which are predicted by the hyperbolic method, three-point method and Asaoka method is used as the final settlement of embankment. The constant preloading can be removed to lay ballastless track after 5 months in the section of pile thrusted-expanded in column-hammer and after 8 months in the section of cement soil pile. But it may need to continue for a long time in the section of dynamic compaction.

Key words: passenger dedicated line, collapsible loess, ground treatment, embankment, settlement