Abstract: Based on an in-situ test of single diaphragm wall under head horizontal static loading in loess subgrade, the level loading distortion characteristics were analysed and studied, with the increase of head horizontal load, the variation rules along the depth of the different section bending moment, horizontal displacement of diaphragm wall and loess resistance etc. were obtained. The results indicate that the third segment of upside diaphragm wall is influenced distinctly by the head level loading; horizontal displacement and bending angle of diaphragm wall presented nonlinearly decreasing down the depth, and increased with the development of head loading; the maximum values of bending moment of diaphragm wall and loess resistance take place within a range of depth below the earth's surface, the position of maximum and zero values of bending moment and loess resistance transferred gradually down along with diaphragm wall that accompanied with the head level load increasing; and curves of loess resistance –horizontal displacement takes on the properties of hyperbola; the maximum shearing force values of diaphragm wall occured on the surface, and shearing force varied nonlinearly down with the diaphragm wall.

Key words: diaphragm wall, loess subgrade, in-situ test, soil resistance, bending moment