Action mechanism of geogrid reinforced expansive soil slope in high-speed railway
Geogrid reinforced treatment is a key technology to solve the problem of expansive soil slope.In order to study the interaction mechanism between geogrid and expansive soil,the reinforcement design and the calculation of the geogrid pullout stability were carried out based on the south line of the Guinan railway project.Design solutions that consider the lateral swelling of expansive soils and the restraint effect of geogrid were used in actual projects.The change characteristics of moisture content,stress,geogrid strain and displacement of reinforced slope under natural rainfall and evaporation climate were monitored through on-site buried monitoring elements.The results are shown as follows.Under the influence of lateral swelling and geogrid restraint,the safety factor of geogrid still meets the specification requirements.Based on the monitoring data,it is found that the fluctuation of volumetric moisture content gradually decreases from shallow to deep due to the influence of the atmospheric environment.The tendency of geogrid strain is the same as the tendency of soil stress,which changes in a"wave"pattern with seasonal dry and wet climates.The soil near the slope surface is more significantly influenced by the dry and wet cycles of the atmosphere and is sensitive to rainfall infiltration,with more rapid changes in geogrid strain and earlier peak time.The peak strain of the geogrid is much smaller than the allowable tensile strain,and the accumulated horizontal displacement of the slope is small,indicating that the risk of slip damage of the reinforced slope is lower.During the rainfall process,the geogrid exerts elastic restraint on the soil,allowing a certain degree of swelling of the slope surface,releasing the swelling potential of the slope due to humidification,thus avoiding progressive landslides resulting from increased lateral stress on the slope.The mechanism of"controlling swelling with flexibility"of geogrid reinforced expansive soil slope is fully reflected.The research results can provide theoretical and technical support for the design and construction of high-speed railway geogrid reinforced expansive soil slopes.
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