Yuta KONNO

Experimental Study on Consolidation Properties of Naturally Deposited Clay and Reconstituted Soil

Satoru OHTSUKA

In Niigata Prefecture, there is soft ground consisting of alluvial lowlands (coastal plains, river plains), and in addition to wide-area land subsidence due to the use of groundwater for snow removal, long-term residual subsidence is a problem in road embankments, etc. There is. In recent years, attempts have been made to interpret the consolidation settlement of cohesive soil by the isotach law. However, the difference in behavior due to the physical characteristics of cohesive soil has not been fully clarified.
In this study, we conducted a constant strain rate consolidation test (CRS test) with different strain rates for naturally deposited clay (undisturbed state) and reconstituted soil of samples collected in the former Shiunjigata, Niigata Prefecture. The purpose of this is to understand and consider the strain rate dependence of the sample.
Naturally deposited clay and reconstructed soil are basically soils with the same particle size composition, but the difference in behavior between them is considered to be due to the structure. As a way to understand the consolidation phenomenon, we will investigate the effects of consolidation characteristics, velocity effect, and load history.
A constant strain rate consolidation test was carried out for naturally deposited clay and reconstituted soil with the same particle size distribution, and differences in compressive strength due to strain rate were observed in both samples. While the overconsolidated region of the naturally deposited clay is clear, the compression index at normal consolidation is larger than that of the reconsolidated soil.
From the results of the variable speed CRS test, the compression behavior according to the isotach theory was confirmed in both samples. It was confirmed that the cohesive soil stores the pre-consolidation stress according to the strain rate as a state variable.