Evaluation of Stiffness Degradation Curves from in Situ Tests in Various Soil Types

Godlewski, Tomasz

doi:10.2478/ace-2018-0075

Cited by 5 publications

(5 citation statements)

References 21 publications

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“…Again, the data for similar soils were compared with the locally obtained data. The stiffness reduction values are moved to the right against the values obtained for comparative soils, despite a lower value of the porosity index and effective strain, which are among the essential factors affecting the stiffness characteristics [76,77]. It can also be seen that above 0.2% strain, stiffness degradation is higher than in other soils.…”

Section: Discussionmentioning

confidence: 69%

Characteristic of small-strain stiffness of fine-grained soils based on advanced laboratory tests

2023

Archives of Civil Engineering

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The non-linearity of the modulus in the zone of small deformations has become one of the three basic concepts of modern soil mechanics, together with "effective stresses" or "critical state". It is therefore necessary to obtain suitable parameters to describe these phenomena through the development of modern measuring equipment and new research methods. Limitations in the availability of the research area or research equipment indicate the need to create a data set, in the formula of regional assessments. The article presents a compilation of data on the deformation characteristics of soils covering about 75% of the country's area, which are the most common subsoils for building. Descriptions, images of microstructures, and a record of mechanical parameters are presented for various age-old glacial clays and marginal clays and loesses. Emphasis is placed on parameters obtained from triaxial tests, including the determination of the shear modulus at small deformations obtained from BET measurements. In combination with the patented solution of sample strain measurement, complete deformability curves of the tested samples were obtained, indicating model reference curves developed for the above soil types. The statistically significant amount of data collected allowed the creation of a specific portfolio for selected soils as a starting point for assessing deformability. This corresponds to the current expectations regarding the characteristics of the behaviour of the substrate in the full spectrum of stresses and deformations, obtained from different types of tests, which, as in the case of soil stiffness degradation, together allow the correct determination of the necessary parameters.

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Section: Discussionmentioning

confidence: 69%

Characteristic of small-strain stiffness of fine-grained soils based on advanced laboratory tests

2023

Archives of Civil Engineering

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“…In addition, the course of deformation is affected by several other factors, such as the state of stress, degree of saturation, load velocity, time, degree of pre-consolidation, etc. [15,16]. Soil stiffness should be described by a function whose graphical representation is called the stiffness degradation curve [15].…”

Section: Soil Stiffnessmentioning

confidence: 99%

Geotechnical Interpretation of the Geological Structure of Loess Covers in Lublin Region

Nepelski

2023

Architecture, Civil Engineering, Environment

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The characteristic feature of the geological structure in the Lublin Region is loess covers, which at the same time constitute the main subsoil for setting building structures. Geological structure is the basis for developing a geotechnical model of the subsoil, which may be identical to the geological model. However, these two types of models in many cases should differ, because the geotechnical model is developed depending on the type of structure, its dimensions, the method and depth of the foundation, and the loads transferred. Identifying geological layers only on the basis of lithology and subsoil state leads to significant and excessive simplification, especially when these layers occur at different depths. Soil stiffness and its bearing capacity depend not only on the state, i.e. wetness but also on several other factors which are difficult to identify based on a superficial macroscopic assessment, even with the verification of individual samples with laboratory tests. A good foundation for the geotechnical assessment of the subsoil is provided by in situ tests such as CPTU and DMT, which allow for a statistical evaluation of parameters. The work presents the methodology for creating a geotechnical model of the loess subsoil based on in situ tests.

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“…the geotechnical documentation, i.e. 12 m below ground level [6,12,21,[24][25][26]. The increase in the modulus of elasticity was performed in relation to two separated soil layers located at the depths of 12 -20 m (layer A) and 20 -30 m below ground level.…”

Section: Calibration Of the Numerical Modelmentioning

confidence: 99%

“…The analysis of the literature, i.a. [24][25][26][27] shows that in terms of the so-called small deformations of the subsoil, which concerns the layers of the subsoil lying deep, usually below the ground recognition level for the purposes of geological and engineering documentation of the designed building, the values of the E module are greater than in the range of large deformations, sometimes even ten times greater. Strengthening (increasing) the modulus of elasticity E of the deeply lying layers of the subsoil in the zone of small subsoil deformations results primarily from their pre-consolidation.…”

Section: Introductionmentioning

confidence: 99%

Archives of Civil Engineering

Michalak

Przybysz

2021

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The design of new investments with underground floors in the downtown urban fabric calls for determining its impact on existing, often historic, neighboring facilities. The article presents the results of own research on 3D spatial arrangement numerical modeling of this type of investment. The scope of the research includes the analysis of neighboring buildings (including historic buildings), construction of the 3D numerical model, and calibration of the subsoil model taking into account the actual results of geodetic measurements. Own research as well as the completed housing development complex in Poland, downtown Warsaw, including data from project design and implementation documentation serve as the basis for research and analysis. As a result of said research and analysis, it was found that 3D computational models allow mapping of actual impacts within the designed new buildings and neighboring buildings, and as consequence -after appropriate calibration -a good reflection of soil displacements in the area of the planned investment. The knowledge of the anticipated values of soil displacements related to erecting new buildings is necessary at the design and implementation stages to ensure safety in all phases of works of existing buildings.

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Evaluation of Stiffness Degradation Curves from in Situ Tests in Various Soil Types

Cited by 5 publications

References 21 publications

Characteristic of small-strain stiffness of fine-grained soils based on advanced laboratory tests

Characteristic of small-strain stiffness of fine-grained soils based on advanced laboratory tests

Geotechnical Interpretation of the Geological Structure of Loess Covers in Lublin Region

Archives of Civil Engineering

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