Basing on the differential equation of slip strain, the paper establishes the additional deformation equation produced by slip of the partial shear connection steel-concrete composite beam and the general formula of the deformation calculation of the composite beam.

Under continual stress loading,the experiment relationship between additional plastic deformation and the stress showed a bu.

This paper, based on the field investigation and the tests of rail-bed soil samples,analyses have been made about the special engineering geological environment of the railbeds and two kinds of environmental engineering geological effects which are refered to additional deformation effect and quick weathering effect.