Composition and strength of Middle Pleistocene till in Lithuania

Abstract

In Lithuania, the upper part of the Earth's crust was formed during the Pleistocene. Only a small part of Lithuania is a relic of the previous Medininkai stage (Lonian) glaciation in the Middle Pleistocene (Chibanian Age), which occur on the surface only in the southeastern area. Medininkai glacial period till soils are an almost unstudied soil type in Lithuania. Due to geotechnical investigations on new construction sites, an opportunity appeared to provide experimental investigations with Medininkai glacial period till soils. One of the main challenges of this research is to collect a perfectly undisturbed sample that would reflect the in-situ conditions. The Medininkai glaciation till soil is a mixture of different portions of clay, sand, and gravel and are different from other detectable till soils globally and unique. The main purpose of this study is to explore and review the strength and deformation properties of till soils of the Medininkai glacial period. Triaxial testing and oedometer tests were used for soil investigation in order to achieve the aim of the study. During the in-situ tests, cone penetration tests were performed as well as the borehole data was described. In this paper, the most important researches were achieved due to comparison single-stage triaxial (SST) and multi-stage triaxial (MST) test methods applying different soil testing conditions. It was concluded that there are no significant differences, only small due to moisture content and drainage conditions. Also, based on different calculate method for OCR evaluation was determined that this till soil is overconsolidated.