It is very important to clear up relations between variation of groundwater and soil mass deformation in disaster of mountain area, so far as the mechanism is elucidated. As an existing condition of groundwater in mountain area is very complex, there are some fairly difficult problems to make clear the relation between the existing condition of groundwater and the disaster.
Judging from conditions of eruption or loss circulation of water during bore hole drilling and from geological condition and fissure condition in bore holes in landslide area. It seems that some layers with groundwater exist in landslide area, and it is conjectured that each groundwater shows different behavior and gives different effects to the deformation of soil mass. We considered that a all-strainer-type bore hole did not apply to make clear the behavior of each groundwater.
So we carried out investigations emphasizing on the behavior of each groundwater in a landslide area in Kobe Group.
The results are shown as follows.
There are roughly four types of groundwater, that is.
1. shallow residential groundwater in detritas and terrace deposits(A);
2. shallow flowing groundwater in detritus and terrace deposits(A');
3. middle groundwater in the Kobe Group(B); and
4. deep groundwater in the Arima Group(C).
The existing conditions of these groundwater are as follows; A is free groundwater