| Abstract [eng] |
Undrained Shear Strength Comparative Analysis of Different Methods. The master thesis is composed from 4 different sections: theorethical, methodological, practical and comparative. In theorethical section there is description about undrained shear strength (su) as well as previous investigation related to su correlation with different in situ and laboratory testing. In methodological part you can find the description of variuos types of investigation which have been used to determine su values. In practical section there is indication about physical and mechanical parameters of soil as well as results of completed investigation. The comparative part presents the comparative analyses between undrained shear strength and physical paramaters of soil using different methods of investigation. The main objective of this master thesis is comparition of undrained shear strength which is determined using different methods of field and laboratory testing. To fullfill this goal 39 undisturbed samples have been recovered from 15 boreholes from 2 to 20 m depth in glacial soil in Kaunas city. These samples have been tested in laboratory, additionally to that, the strength of these samples have been determined using pocket torvane and pocket penetrometer. Furthermore, next to each borehole location cone penetration tests (CPT) have been performed. For this study analysis several types of the soil have been analysed. Largely part of the samples were taken from sandy silty clay, more rear sampling was done in sandy clayey silt, silty clay and clay. The dependance between undrained shear strength and physical parameters of the soil is quite low, you can see it from correlation coefficiant (R), its range is from 0,4 to 0,62. The better dependance of undrained shear strength is with natural moisture content and natural density (R > 0,5). Only dependance of correlation between sandy silty clay undrained shear strength and soil physical parameters was considered as satisfactory. The correlation coefficient (R) vary from 0,6 to 0,87. The highest average values of undrained shear strength were determined by calculation of CPT results, the lowest – during pocket torvane. There was clarified that the best calculation of undrained shear strength using CPT data is to use correlation coefficient (Nk)=20. From this study there was clarified that the best correlation dependence of undrained shear strength is between direct shear test, pocket torvane, pocket penetrometer and values received from CPT data. The correlation coefficient (R) vary from 0,859 to 0,963. |
