Study on the Constitutive Relations for the Quasi- overconsolidated Soils, Especially, Long-Term Consolidation

首先，利用扫描电子显微镜和各种物理测试设备对天然土壤（大阪海底冲积洪积海相粘土和琵琶湖沉积物）的理化特性进行了研究。人工胶结粘土与天然胶结粘土具有相似的特性。由此，我们可以讨论地质胶结对土壤结构的影响。其次，在室内进行了人工胶结粘土的各向同性固结不排水压缩试验和各种固结试验。根据试验结果，从二次压缩和胶结的角度讨论了准超固结土的长期固结。研究了胶结粘土的力学性能。利用SEM专用直剪试验设备，观察了剪切过程中土体颗粒的运动和剪切带的形成。最后，讨论了考虑时间硬化因素建立拟超固结粘土本构关系的可能性。

First, a study on the physico-chemical characteristics of the natural soils (Osaka seabed aluvial and deluvial marine clays, and sediment of Lake Biwa) using SEM and some kinds of physical testing equipments was carried ot. Also used were the artificial cemented clays which have similar characteristics to the natural cemented clays. From the results, we were able to discuss the effect of geological cementation on the soil structure.Secondly, not only the isotropic consolidated-undrained compression tests but some kinds of consolidation tests were performed in the laboratory with the artificially cemented clays. From the results was discussed the long-term consolidation of the quasi-overconsolidated soils from the view points of the secondary compression and the cementation. Also investigated was the behavior of the cemented clays. Moreover, the movement of soil particles and formation ofshear bands during shear were observed, using the special direct shear test equipment in SEM.Finally, We discuss the possibility of establishing the constitutive relations of the quasi-overconsolidated clays taking the time-hardening factor into consideration.