The mechanism of piping failure and disaster prevention systems

为了研究大气压对滑坡的影响，在九州岛进行了现场观测和大型洒水试验。在高原，这是由白须，在九州，几乎总是空气压力在一口井是类似于大气压力和空气没有得到从井。然而，当大气压力下降时，空气压力大于大气压力。在同一事件中，从另一口称为s3的井中观察到了气流。这些现象之间有一个时间差。水系统中的S1可能与S3不同，因此在“空气系统”中也可能不同。在实验中，我们将空气抽到沙坡下。无论是抽高压空气还是抽低压空气，边坡内的气压都没有太大的差别。而当抽入高压空气时，流量、水头、水力梯度等参数发生明显变化。因此，孔隙气压力对滑坡的影响不是直接作用于砂土，而是通过增加地下水的水力坡降间接作用于砂土。

To examine the effects of air pressure under the grand for the landslide, field observation in Kyushu island and a large-size sprinkling experiment were conducted. At tableland, which is composed of Shirasu, in Kyushu, nearly always air pressure in a well was similar to atmospheric pressure and air did not get out from the well. However air pressure was bigger than atmospheric pressure while atmospheric pressure was falling. At the same event, an air flow was observed from another well called s 3. There was a time lag between these phenomena. The s 1 may different from s 3 in water systems, so it might different too in "air system". In the experiment, we pumped air to under a sand slope. Air pressures in the slope were not different so much even though we pumped high pressured air or low pressured air. However, when we pumped high pressured air, water daters changed clearly, for instance, discharge, pressure head, and hydraulic gradient. Therefore, effect of the pore air pressure for the landslide do not affect sand directly but indirectly though increasing of the hydraulic gradient of groundwater.