Characteristics and Countermeasures of Slow Small Deformation Geological Diseases of Mountain Railway
Research purposes:In recent years,many mountain railways in China have experienced small deformation geological diseases such as subgrade arching,tunnel floor heave and bridge offset.The deformation is generally tens of millimeters or even hundreds of millimeters,which seriously affects the smoothness of the rail surface and leads to different degrees of speed limit operation.Through the analysis of three typical cases,the engineering characteristics and deformation causes of various small deformation geological diseases were studied,and the prevention and control countermeasures with the engineering practice were presented.Research conclusions:(1)The geological diseases of small deformation of arch on subgrade mostly occur in deep and wide cutting sections,which are mainly caused by the continuous deformation of gently inclined soft rock strata caused by the coupling effect of unloading rebound and expansion creep.The prevention and control measures of"stress isolation,strain energy dissipation and structure detachment"can be adopted.(2)The small deformation geological disease of bridge offset is easy to occur in the slope zone composed of broken rock and soil mass with steep terrain cutting.It is in the creep stage of landslide brewing period.The creep body should be used as the landslide body,and the measures of intercepting drainage and retaining should be taken to improve its stability.(3)The small deformation geological diseases of tunnel floor heave mostly occur in the complex section of geological structure environment,and the flexural fold type floor heave creep deformation of unloading relaxation-bending slab coupling occurs.The prevention and control measures of"dewatering pressure,adjusting curvature,increasing thickness and increasing strength"can be comprehensively adopted.(4)The research results of this paper have guiding significance and application value for the follow-up comprehensive investigation and treatment of slow-moving and small-deformation geological diseases of mountain railways.
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