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Investigation of the rheological properties of soils for the assessment the base stress-strain state


Author: Cîrlan Alexandru
Degree:doctor of engineering
Speciality: 05.23.01 - Building Elements and Buildings
Year:2019
Scientific adviser: Vladimir Polcanov
doctor, associate professor (docent)
Institution: Technical University of Moldova

Status

The thesis was presented on the 15 March, 2019
Approved by NCAA on the 9 July, 2019

Abstract

Adobe PDF document – 0.77 Mb / in romanian

Thesis

CZU 624.131:624.137(478)(043.3)

Adobe PDF document 11.03 Mb / in romanian
269 pages

Keywords

foundation ground, excavation slopes, sarmatian clays, strength, stability, creep deformations, rheology, calculation methods, finite element method, PLAXIS

Summary

Thesis structure: Introduction, four chapters, conclusions and recommendations, bibliography (203 sources). The content is presented on 134 pages of the main text; 22 tables (excluding appendix), 32 figures, 18 appendices. The results of research are published in 8 scientific papers.

Area of research: excavations slopes and buildings and structures foundations located on landslide slopes, landslide areas.

Aim of the research: development a method for assessing the stress-strain state of the base, to ensure long-term stability of excavations slopes and reliable work of foundations, based on the study of rheological properties of soils.

Objectives are determined by the main objective of the study and are aimed at: studying the possible role of the rheological properties of clay soils in the loss of excavation slopes stability; identification of the main factors that determine the strength properties of Sarmatian clay; establishing the role of creep deformation on stability loss of deep excavation slopes; Scientific novelty and originality. The influence of various factors on the resistance of the Sarmatian clay-sandy soil from Republic of Moldova was studied, determining the influence of the degree of disruption of the natural structure, consistency, residual resistance on their resistance; the rheological characteristics of the Sarmatian clays and their influence on the stress-strain state of the slopes of the multilayer slopes of excavations were determined; the conditions and causes of the deformation of the excavation slopes executed in these soil layers were determined.

The importance of the scientific problem consists of developing a method that allows to take into account the rheological properties of clay soils to design the slopes of deep excavations and the pits on transport highways in order to ensure local and long-term stability and increase the validity of stability prognoses.

Theoretical significance and applicative value of the thesis lies in possibility of using the obtained results for development of landslide slopes, for designing and constructing of deep excavations, for calculating of stress-strain state of the base composed in the active zone by Sarmatian clays, and also in assessing the long-term stability of the slopes that should be built up, for excavation of foundation pit and development the complex of preventive anti-deformational measures. The resulting dependences, determining the strength of clays, will shorten the duration of experiments.

Implementation of the scientific results The proposed method was used to design the excavation slopes for reconstruction project of M21 road (Chisinau-Dubasari-Poltava), and calculation the slopes stability of 182,0-182,4 km section of M5 road and appreciation of slope stability on V. Trandafirilor Street, no. 4, mun. Chisinau, affected by landslides.