Abstract:Abstract : Research purposes : Under train load, railway ballast is apt to be fouled or broken which may result in differential settlement of sleeper or breakage of track geometric alignment. In some countries there are experimental results indicating that the particle breakage and deformation performance of railway ballast can be improved effectively in geogrid - reinforced ballast. The research purpose of this paper is to study the deformation rules of geogrid - reinforced ballast and its influence factors under train load. Research conclusions:(1) Geogrids placed in railway ballast can not only curtail the lateral displacement and vertical settlement of ballast, but also curtail the differential settlement of ballast that arises due to the disparity in vertical stress along the tack length. The optimal location is in the subballast. (2) Within a range of geogrid elastic modulus, both lateral displacement and vertical settlement of railway ballast decrease with the increase of geogrid elastic modulus. (3 ) With the same ballast parameters and vertical stress at the surface of subgrade, the vertical settlement is affected by the lateral movement of ballast. In this paper both embody obvious linear correlation. (4) The research results can provide references for design, reconstruction and maintenance of railway ballast.