On properties of groundwater in kunimi landslide area.

Abstract

Analysis of groundwater properties was conducted in the fall of 1985 at the Kunimi landslide area, where a previous survey had been carried out in the summer of 1984. As a result, no particular change is found either in composition or in concentration.Consideration is made on the thermodynamic stability of minerals. It is clarified that the stability of montmorillonite has relations with the properties of groundwater inside the sliding block while the stability of kaolinite has relations with those outside the sliding block. These results agree with those obtained in the previous survey.The present study also includes an analysis of the properties of groundwater which comes from a fault existing at 206m from the mouth of a draintunnel. An investigation is performed on the thermodynamic stability of minerals contained in the groundwater. As a result, it is suggested that there exist a groundwater stream flowing on a slip surface (an upper hard rock) in the fault at 206m from the mouth of the draintunnel in the Kunimi landslide area.The present survey there confirmed that smectite (=montmorillonite) existed in clay layers near the slip surface. The smectite appeared to have formed from zeolite contained in tuff. Thus a consideration is made on the stability of montmorillonite coexisting with HCO3-. It is shown that the composition of groundwater shifts from the stable kaolinite region to the stable montmorillonite region as the HCO3- con centration exceeds about 40mg/l. These findings also agree with those obtained in the previous study.