| Principal Investigator: | Ing. Bulko Roman, PhD. |
| Project Duration: | 4/2019 - 12/2019 |
| The project focuses on simplifying the transition between field or laboratory tests and constitutive models and their calibration in the environment of geotechnical tasks and computational soil mechanics. A constitutive model that captures the behavior of a material within a general range of loading conditions is essential for simulating complex boundary problems in soil mechanics and geomaterials. Ideally, conventional constitutive models used in geomechanics (MC, CamClay, Hypoplasticity) could be parameterized using a single (complex) test, which is at least partially fulfilled by the penetration test. The principle of the CPT test is the static insertion of a measuring cone using a system of steel rods into the investigated environment at a constant rate. Direct evaluation of constitutive parameters in the case of the CPT test is considerably challenging but shows potential when using alternative approaches such as constitutive models based on neural networks. | |
| Principal Investigator: | Ing. Bulko Roman, PhD. |
| Project Duration: | 9/2021 - 8/2022 |
| In today's fast-paced practice, we encounter non-compliance with the standard "STN EN ISO 22475-1 Geotechnical investigation and testing. Sampling methods and groundwater measurements. Part 1: Technical principles". This standard includes principles for sampling and handling soil samples. The principles of sample handling are often violated, the strength states of samples are not maintained, and it is common for such samples to arrive at the geotechnical laboratory in a disturbed state. Then it becomes difficult to conduct a comprehensive investigation of the deformation or strength properties of soils on the given sample. Therefore, the project will focus on determining the deformation and strength properties of fine-grained soils on reconstituted samples and their comparison with naturally deposited soil samples. Reconstituted soils are soils whose moisture is adjusted to the liquid limit wL (optimal moisture wL<w<1.5wL) and which have been consolidated, preferably under one-dimensional conditions (Burland, 1990). By adding water to the soil and mixing them, we create a homogeneous mass, and by consolidation, we remove excess air bubbles. | |
| Principal Investigator: | Ing. Bulko Roman, PhD. |
| Project Duration: | 9/2022 - 8/2023 |
| This project will follow up on the previous project titled: "Mechanical Behavior of Reconstituted Soil" with identification number 12787. In the previous project, a device for one-dimensional soil consolidation was constructed. Furthermore, it was possible to investigate the deformation characteristics of naturally deposited and reconstituted soils and compare them. This project will deal with the shear strength parameters of reconstituted fine-grained soils. The triaxial apparatus of the soil mechanics laboratory of the Department of Geotechnics at the University of Žilina will be used for the test results. In laboratory conditions, we often encounter non-compliance with the standard "STN EN ISO 22475-1 Geotechnical investigation and testing. Sampling methods and groundwater measurements. Part 1: Technical principles". This standard includes principles for sampling and handling soil samples. The principles of sample handling are often violated, the strength states of samples are not maintained, and it is common for such samples to arrive at the geotechnical laboratory in a disturbed state. Then it becomes difficult to conduct a comprehensive investigation of the deformation or strength properties of soils on the given sample. Therefore, the project will focus on determining the strength properties of fine-grained soils on reconstituted samples and their comparison with naturally deposited soil samples. In laboratory conditions, we can simulate various conditions and stress states that we will consider relevant. Reconstituted soils are soils whose moisture is adjusted to the liquid limit wL (optimal moisture wL<w<1.5wL) and which have been consolidated, preferably under one-dimensional conditions (Burland, 1990). By adding water to the soil and mixing them, we create a homogeneous mass, and by consolidation, we remove excess air bubbles. | |
| Principal Investigator: | Ing. Bulko Roman, PhD. |
| Project Duration: | 10/2023 - 9/2024 |
| The project focuses on the static penetration test with a seismic cone, known as the SCPTu test. Using a hammer impact, shear waves - signals propagating through the medium - are generated, which are used as one of the methods for characterization and evaluation of soils in geotechnical practice. However, this method of testing the subsoil is only a secondary principle of the test. The primary principle of the static penetration test is the cyclic insertion of a measuring cone together with rods at a constant rate, providing a continuous image of the tested soil subgrade. The aim of the project is to evaluate and compare the results of SCPTu with other geotechnical methods and to examine procedures for processing SCPTu signals. A partial objective is to design a computational environment for evaluating the SCPTu test. This work could bring new knowledge and improve the efficiency and accuracy of geotechnical tests, which may contribute to greater reliability of geotechnical designs and structures. | |
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- UNIZA Projects
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Analysis of Geotechnical Tests for the Assessment of Small-Strain Stiffness of Soils
| Principal Investigator: | Ing. Bulko Roman, PhD. |
| Researchers: | Ing. Gago Filip, PhD., Ing. Mihálik Ján, PhD., doc. Ing. Mužík Juraj, PhD. |
| Project Duration: | 11/2024 - 11/2027 |
| Engineering geological (EG) survey is a key element in the process of planning, design, and implementation of geotechnical projects. Its main objective is to obtain detailed information about the geological conditions at the site of the future construction and their impact on structural stability and safety. In this research project, we focus on the integration of laboratory and field tests in assessing the stiffness and strength of soils at small strains. For this purpose, we will use Bender elements in the geotechnical laboratory under controlled conditions and measured data from SCPTu tests under real conditions. Through laboratory tests with Bender elements, we will obtain a reliable method for determining the shear wave velocity, while measured data from SCPTu tests provide us with information in real conditions. The integration of these two methods will allow us to gain a comprehensive view of the mechanical properties of soils and provide us with important data for engineering applications in the field of geotechnics and civil engineering. | |