Three dimensional resistant mechanism in a landsliding body and function of forest root system.

通常，滑坡发生的稳定性是通过在边坡纵断面上产生的滑面和土体的力的平衡来评估的。而树木的阻力作用在滑动面上。但是，已经证实，尽管根块没有到达滑动面，但根块形成了一个阻力系统，这一事实表明存在另一种机制。我们的现场观测提供了一个新的想法，即在滑动体中潜在形成的拱结构作用于三维机构。这种结构表明，许多坚固的块体（如树根）的存在增加了对滑坡发生的阻力，尽管块体在滑坡表面不起作用。这种拱形结构向侧面传递力。这些力最终被斜坡两侧更稳定的部分所支撑。通过室内模型试验验证了结构的动力作用，在滑坡、滑坡、冰川等滑动区域普遍认识到不连续块体作为拱的存在。

Usually, the stability of a landslide occurrence is evaluated by the balance of forces generated on the slide surface and soil mass in a longitudinal section of a slope. And resistance of forest tree works on the sliding surface. But, it has been confirmed that root blocks make a resistant system, in spite of that the root blocks do not reach the sliding surface, and this facts suggest existence of another mechanisms. Our field observations provide the new idea, that an arch structure latently formed in the sliding body works on three dimensional mechanism. This structure is indicated by which existence of many strong blocks such as tree roots increase the resistance against a landslide occurrence, although blocks do not work on the slide surface. This arch structure ttransmits force sidewards. These forces are finally supported my more stable parts in both side of slope. Thus dynamic action of the structure was checked up by the model experiment in our laboratory, and existence of discontinuous blocks as a arch were recognized universally in a sliding area such as lndslide, landcreep and glacier.