抄録
As the argillaceous sediments are buried deeper and deeper, the sediments become solidified gradually by compaction, dissolution and lithification through overburden load. Even the argillaceous sediments in the same geological age bear different characteristics physically, mechanically and chemically due to the different sedimentary conditions. Argillaceous sediments were sampled in the seven different sites throughout Japan and various kinds of laboratory experiments including physical, mechanical, chemical and mineralogical tests were conducted.
In the part I of the report, the burial depth of these argillaceous sediments was examined, mainly based on the physical and mechanical causes, that is, the relationship between unconfined compressive strength and the state of packing among grains by compaction.
As a result of these examinations, it was proved that compaction and lithification mainly caused by overburden load and the burial depth of these argillaceous sediments could be estimated by their consolidation yield stress obtained by laboratory tests.
These burial depths coincided with the value obtained from the porosity of argillaceous sediments in the oil field in Japan (Aoyagi. 1978) and with the value from the relationship between unconfined compressive strength or porosity and burial depth of argillaceous sediments in Boso peninsula (Okamoto and Kojima. 1981)
The unconfined compressive strength, however, varies much with the amount of micrograin or filling material of sediments.
The examination for chemical and mineralogical tests was described in the part II of the report.
