Use of the laboratory tests of soil modulus in modelling pile behaviour

The problem is a continuation of the research conducted at the University of Warmia and Mazury in Olsztyn, Institute of Building Engineering. It concerns the development of methods for the interpretation of the shear modulus measurements based on the tests conducted on a torsional shear (TS) apparatus. The issue has significant importance in determining the deformation parameters, essential to perform numerical simulations of the interaction between a geotechnical structure and the subsoil. The purpose of this study was to conduct a comparative analysis of the various methods of interpretation of research results based on direct and reverse analysis, as well as automated classification of the first cycle of the relationship between the shear stress and the shear strain components obtained from the TS test. The methodology for verification of the presented interpretative methods consists in carrying out a series of laboratory tests on non-cohesive and cohesive samples of different granulation and state parameters. The course of the research includes the following steps: elaboration of the granulometric composition of several samples of soil, determination of soil index properties and execution of TS tests. Various methods of interpretation of obtained results were taken into account, in addition to conducting a comparative analysis. The study used a non-standard interpretation approach consisting of analysing one-fourth of the hysteresis loop of the first load–unload cycle of the tested samples. The obtained results confirmed the hypothesis that it is possible to estimate the degradation value of the shear modulus based on a part of the TS test results carried out under quasi-monotonic load conditions. The proposed methods of interpreting test results have confirmed their high usefulness, which is devoid of the uncertainty associated with standardised resonant column/TS testing.

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“…for tangent modulus (7) where the constant of the hyperbolic curve is taken in the range of R f = 0.5-0.9.…”

Section: Degradation Functions Of G Modulusmentioning

confidence: 99%

“…In many calculation methods for subsequent phases of subsoil loading, it is required to use a tangent modulus, the value of which changes depending on strain and stress. Such an analytical solution was used, among others, in the method of determining the settlement curve of a single pile loaded with axial force [7].…”

Section: Introductionmentioning

confidence: 99%

Interpretation of shear modulus degradation tests

Srokosz

Dyka

Bujko

2018

Studia Geotechnica Et Mechanica

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“…As suggested by Dyka (2012), the stiffness (modulus) of a soil layers is the most important engineering property for geotechnical problems which are related to deformation or settlement issues. However, as soil may go through a number of loading cycles (loaded, unloaded and reloaded), the response of the soil in terms of magnitude of deformation / rebound, and thus gradients associated with constructed stress / strain curves, may change significantly.…”

Section: A1 Definition and Importance Of Modulusmentioning

confidence: 99%

Assessment of some engineering properties and testing methods of residual soil and highly weathered rock materials in QLD, Australia

Lacey¹

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-i - AbstractThis research project was concerned with the investigation of material parameters associated with the 'residual soil' profile of South East Queensland (SEQ) and their variation across the full weathering profile (residual soil and highly weathered rock materials). Based on an assessment of their prevalence throughout the SEQ region, the specific 'residual soils' investigated by this study were subsurface materials that exhibited properties that were primarily determined by the soil skeleton and remnant rock structure, contained a significant coarse sized component, and did not demonstrate behaviours influenced by their fines (clay mineralogy) component. A review of historical records held by a major Queensland government department revealed that such materials were becoming increasingly underrepresented in the frequency of material testing, regardless of the importance their insitu deformation and strength properties could have on geotechnical design projects.The research initially identified a lack of a simple field tests able to determine the insitu deformation parameter of a 'residual soil' as a void in the current geotechnical knowledgebase. To overcome this shortcoming, the initial section of this thesis details fieldwork in which the use of a Light Falling Weight Deflectometer (LFWD) for the direct measurement of insitu modulus parameters was developed. Comparative testing was undertaken with the Plate Load Test at three (3) discrete SEQ sites, and with the DCP at an additional seven (7) SEQ sites. The results of this testing demonstrated the suitability of the LFWD for use an investigative tool for residual soil and highly weathered rock materials. The results of the LFWD characterisation of the near-surface produced an insitu modulus parameter of a higher sensitivity and with lower inherent variation when compared to the results of other conventional site investigation techniques.The focus of the research was transferred deeper into the typical SEQ weathering profile, and studied material parameter variation across the gradational change between 'soil' and 'rock' materials. Although the distinction is frequently subjective, and often recorded at an arbitrarily depth during site investigations, the field designation of a material into either of these two (2) categories considerably affects the design material parameters assigned. By analysis of the penetrative ability of various types of drilling bit used for borehole drilling in site investigation, this research demonstrated that drill bit 'refusal' does not typically occur at the soil / rock interface. Instead, 'refusal' generally occurs within highly to moderately weathered rock. The completed analysis has demonstrated that the depth of 'refusal' is actually a function of (a) the type of drill bit; (b) rock strength; and (c) defect spacing within the rockmass. The project presented the likely (statistical) material parameters associated with the 'refusal' depth of various drill bit types, and that drill bit 'refusal' could realist...

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Identification of Elasto-Plastic Phenomena in Soils in the Range of Small Strains

Bujko

2019

IOP Conf. Ser.: Mater. Sci. Eng.

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Use of the laboratory tests of soil modulus in modelling pile behaviour

Cited by 3 publications

References 1 publication

Interpretation of shear modulus degradation tests

Interpretation of shear modulus degradation tests

Assessment of some engineering properties and testing methods of residual soil and highly weathered rock materials in QLD, Australia

Identification of Elasto-Plastic Phenomena in Soils in the Range of Small Strains

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