MODEL TEST ON REENFORCEMENT MECHANISM OF GEOGRID-STEEL TUBE EXPANSIVE SOIL RETAINING WALL FOR SLOPE STABILITY OF NANKUN RAILWAY

The reinforcement of expansive soil slope has always been a difficult problem in railway(highway) construction. Conventional rigid structure strictly restricts the deformation of expansive soil,and easily lead to structural failure under excessive force. Instead,the flexible structure also may cause the slope to be damaged by greater deformation. Both of them can not achieve the expectation effect when they are used separately. This paper presents the geogrid-steel tube expansive soil retaining wall. It can coordinate the stress and deformation of the structure reasonably and reinforce the expansive soil slope. This paper uses the similar material model in large scale for the reinforcement test. Expansive soil is used as retaining wall filler. Geogrids and longitudinal steel tubes are used to enhance the integrity and stiffness of the wall. The reinforcement effects of the new and conventional structures are compared under simulated rainfall conditions. Furthermore,the reinforcement mechanism of geogrid-steel tube expansive soil retaining wall is studied,by means of monitoring the horizontal displacement of the retaining wall,the earth pressure on the back of the wall and the deformation of the steel tube. The results show that the deformation of geogrid-steel tube retaining wall is significantly reduced and more coordinated than that of conventional geogrid retaining wall. The bearing capacity of geogrid-steel tube retaining wall is significantly improved. The steel tubes penetrate the wall longitudinally and are rooted in the foundation,effectively improve the stress of the retaining wall. The research results can provide theoretical reference for the selection of reinforcement structure and its structural design of expansive soil slope.