The requirements for field research for Polish conditions demand proper dependences. Dependences based on more than 30 localizations for different genetic types of soils were derived for the area of Poland. Direct results from CPT, DMT and profiles from boreholes have been collected at the test sites for individual localization. For interpretation of results, dependences and diagrams of CPTU versus DMT were created. Correlations on the background of results from literature for different types of soils for numerous research areas were collected, with established dependences for Polish grounds conditions. Additionally some recommendations for the interpretation of the results from CPTU and DMT tests for analysed soils have been proposed.
Accurate frost depth prediction is an important aspect in different engineering designs such as for pavements, buildings, bridge foundations, and utility lines. This paper presents a probabilistic method of assessment of the depth of soil freezing. Annual (winter) maxima of the position of the zero centigrade temperature measured in the soil were approximated by Gumbel probability distribution. Its parameters were estimated using maximum likelihood method. The results received on the basis of data from 36 meteorological stations in Poland and 50 years of observations, as characteristic values with 50-year return period, reflect the influence of the climatic conditions on the freezing depth. On the other hand, the soil structure and its conditions also play an important role in freezing. Nowadays they may be taken into account using correction coefficients. It is concluded that this method is more precise than a method using the air freezing index because through the use of direct measurements it takes into account additional factors affecting the actual depth of freezing. The obtained results are not the same as those given in the older Polish Standard which was based on the simplified and limited data. The results confirm the impact of climate change on ground freezing depth.
From point of view geotechnical parameters evaluation (classifications, interpretations) it is important to determine organic matter content correctly. Most frequently approach is to use for that purpose direct method – loss on ignition at different temperatures. Key factors which influence choosing that approach are: simplicity of this method and non-complex equipment. Thereby, much less used are indirect methods – volumetric. One of indirect methods is common known Tiurin’s method. Organic matter content depends not only from applied method. In case of direct method – loss on ignition at different temperatures, temperature which is applied in examination has also influence on organic matter content. The following article presents results of examinations which gave opportunity to determine to what extent chosen method influences value of organic matter content. The authors were investigated what infl uence has applied temperature in the loss of ignition method. For that purpose as a reference Tiurin’s method was chosen, which generally outputs values lower than the method loss on ignition at different temperatures.
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