研究目的： 近年来,我国开通运营的多条山区铁路发生路基上拱、隧道底鼓、桥梁偏移等小变形地质病害,变形量一般在几十毫米甚至上百毫米,严重影响轨面平顺性,导致不同程度限速运行。本文通过3个典型案例分析,研究各类小变形地质病害的工程特征及变形原因,提出更符合工程实际的防控对策。
研究结论： (1)路基上拱小变形地质病害多发生在深宽路堑地段,主要为卸荷回弹、膨胀蠕变耦合作用导致缓倾软质岩层持续变形,可采用“应力隔断、应变消能、结构脱离”的防控措施;(2)桥梁偏移小变形地质病害易发生在地形切割较陡的破碎岩土体组成的斜坡地带,处于滑坡酝酿期的蠕动阶段,应将蠕变体作为滑坡体,采取截排水和支挡措施提高其稳定性;(3)隧道底鼓小变形地质病害多发生在地质构造环境复杂区段,发生卸荷松弛-弯曲板裂耦合的挠曲褶皱型底鼓蠕变变形,可综合采用“降水压、调曲率、增厚度、提强度”的防控措施;(4)本研究成果可为后续山区铁路慢行小变形地质病害综合勘察与整治提供指导。

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.