STUDY OF COMPATIBILITY OF METHODS FOR LIQUID LIMIT MEASUREMENT ACCORDING TO CZECH STATE STANDARD AND NEWLY ADOPTED EUROPEAN STANDARD STUDIE KOMPATIBILITY METOD PRO MĚŘENÍ VLHKOSTI NA MEZI TEKUTOSTI DLE ČSN A NOVĚ PŘIJÍMANÉ EVROPSKÉ NORMY
The goal of the publication is a correlation between the methodology of liquid limit determination using Casagrande bowls according to the Czech state standard being valid as yet and the methodology on a principle of the conical test according to a newly adopted European standard. It allows a better link of utilization of an extensive statistical set of investigations realized for purposes of foundation engineering in past that are available in Geofond for newly conducted engineering geological studies according to the new European standard related to water contents at the liquid limit for wide-spread clay soils. The sample values ranged from 21.49 to 49.56 % according to Casagrande and in the conical test they ranged from 24.11 to 51.07 %. The difference of the results for identical samples reached values from 1.15 to 4.19 %. The studied mean difference coefficient between methods amounts to 2.55 %.
A statistical reappraisal of the relationship between liquid limit and specific surface area, cation exchange capacity and activity of clays
Abstract More than 500 datasets from the literature have been used to evaluate the relationships of specific surface area (SSA), cation exchange capacity (CEC) and activity versus the liquid limit (LL). The correlations gave R2 values ranging between 0.71 and 0.92. Independent data were also used to validate the correlations. Estimated SSA values slightly overestimate the measured SSA up to 100 m2/g. Regarding the estimated CEC values, they overestimated the measured CEC values up to 20 meq/(100 g). A probabilistic approach was performed for the correlations of SSA, CEC and activity versus LL. The analysis shows that the relations of SSA, CEC and activity with LL are robust. Using the LL values, it is possible to assess other basic engineering properties of clays.
Archaeological Survey of Dangoyama Kofun by 3DGPR
We presented a three-dimensional ground penetrating radar (3DGPR) system for the archeological investigation in a harsh site, where we have to deal with many trees and/or great topographic variations. This system consists of a commercial GPR system with a laser positioning system. With this system, we can move the GPR antenna freely, on which a positioning detector can record accurate position for each GPR data trace. We applied our 3DGPR system at Dangoyama Kofun, a burial mound, in Fukushima prefecture, Japan. A lot of trees and bushes covered the survey area and cannot be cut. We acquired six datasets in two days in this area. We successfully imaged the boundary between the original surface of the burial mound and the covering soil clearly at about 0.3 m depth around the mound. Furthermore, we found some strong reflections appeared at 0.8 m depth in the top area of the mound, which can be from the artificial parts of the burial mound. The results would greatly aid the following archaeological excavation. In addition, we compared the non-interpolated depth slice with interpolated depth slice at same position and demonstrated that the interpolation process on threedimensional GPR data may introduce some artifacts which might mislead our interpretation.