南昆铁路钢管格栅膨胀土挡墙边坡加固机理模型试验研究

膨胀土边坡加固一直是铁路(公路)建设中的难题,常规刚性结构严格约束膨胀土变形,易使结构受力过大而破坏,柔性结构易使坡体变形过大而失稳,往往难以达到预期效果。本文提出钢管格栅膨胀土挡墙,合理协调结构的受力和变形,达到加固膨胀土边坡的目的:膨胀土做挡墙本体填料、土工格栅增强墙体整体性、纵向贯穿钢管提高墙体刚度。采用大比例尺相似模型试验,在模拟降雨条件下,对比该新型结构与常规结构的加固效果,通过监测挡墙水平位移、墙背土压力、钢管变形,研究钢管格栅膨胀土挡墙加固边坡机理。结果表明:钢管格栅挡墙与常规格栅挡墙相比,变形显著降低且更趋协调,承载能力明显提高,纵向贯穿墙体且深入地基的钢管有效改善了墙体的受力。研究成果可为膨胀土边坡加固结构选型及其构造设计提供理论参考。

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.