Full text
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| Author(s): |
Marlísio de Oliveira Cecílio Junior
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Escola Politécnica (EP/BC) |
| Defense date: | 2009-05-06 |
| Examining board members: |
Marcos Massao Futai;
Waldemar Coelho Hachich;
Arsênio Negro Júnior
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| Advisor: | Marcos Massao Futai |
| Abstract | |
Undisturbed samples of a residual soil had been collected from the west zone of São Paulo city, in order to characterize the soil and study its mechanical behaviour. Its mineralogical composition is presented, as well as a microscopic study which identifies some of these minerals and evinces its microstructure. Thus, how the soil mineralogy and microstructure influence its mechanical behaviour is discussed, which was studied by means of oedometer tests and conventional axial loading triaxial tests. One analysed the soil compressibility, permeability, structuring degree, stress-strain relations and yielding, rupture and Critical State envelopes. The soil had been characterized as saprolite, derived from a biotite-gneiss. Based on the results concerning the soil behaviour, three constitutive models were calibrated: linear elastic, elastic perfectly plastic (Mohr-Coulomb), and elastic-plastic with hardening (Hardening Soil). With this mathematical modelling, a three-dimensional numerical model with finite elements was designed, for the purpose of simulating a tunnel excavation and obtaining the stress paths around it due to its excavation. Other triaxial tests were carried out, this time by following the stress paths numerically obtained. The elastic parameters of the three constitutive models had been determined for each stress path and the ground surrounding the excavation had been modelled as a mechanically heterogeneous media. I.e., zones around the tunnel had been limited by its different mechanical properties, as a function of the actual stress path. Finally, the geotechnical parameters determined by different stress paths are compared, as well as the results obtained for both numerical models. (AU) | |