LOESS CHARACTERISTICS AND ENGINEERING MEASURES OF HENGFU SPECIAL RAILWAY IN SHANXI HONGTONG

Hengfu special railway is located in high terrace in Shanxi Hongtong Fenhe valley., Loess is the main engineering geological problem of this project. There are three layer of loess, Alluvial and diluvial causes and age of late quaternary holocene(Q42), the early Holocene (Q41) and late pleistocene(Q3). Three layers are sandy loess, which belong to the hard soil, with low natural gravity, natural void ratio, less natural water content and low liquid limit and plastic limit, small plasticity index and liquidity index, low saturation, large compression coefficient, high velocity, shear strength and bearing capacity of general characteristics. Physical and mechanical indexes of layer 1 and layer 2 loess are close, which are collapsible loess. The indexes of layer 3 are better, not collapsible loess. The field is self collaspsibility. The collapsibility of loess and natural gravity, natural void ratio, natural water content, liquid limit, saturation and shear wave velocity indexes have close relations. The loess collapsibility has larger influence on bridge and roadbed engineering. It should take different foundation type and treatment measures for different project and loess. The different methods of sampling have great influences on the collapsible loess indexes and characteristics, collapsible loess trial pit manual sampling should be adopted.