Banca de DEFESA: Raimundo Francisco Perez Leon

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : Raimundo Francisco Perez Leon
DATE: 14/04/2023
TIME: 11:00
LOCAL: Plataforma Microsoft Teams
TITLE:

Soil-lining interaction of tunnels built in soft soils subjected to pore pressure drawdown

KEY WORDS:

Tunnels; Soft soils; Soil-lining interaction; Physical modeling; Geotechnical centrifuge

PAGES: 169
BIG AREA: Engenharias
AREA: Engenharia Civil
SUBÁREA: Geotécnica
SPECIALTY: Fundações e Escavações
SUMMARY:

In recent years there has been a marked increase in the use of tunnels built on soft soils, especially in urban regions, to serve a variety of purposes, such as transportation (road, rail and subway), and as part of sewage collection systems (Kochen, 2005).
Many cities are developing on soft soils: Shanghai, Bangkok, Kuala Lumpur, Jakarta, Singapore, Bogota, Mexico City, among others. These cities have been presenting related phenomena such as the lowering of water levels in the soil that change the working conditions of underground structures (Rodríguez, 2016).
Measurement of pressure in tunnel lining built in saturated clays in London, Chicago, and Detroit (Peck 1969; Tchebotarioff 1979) shows that vertical pressure evolves over time, sometimes exceeding the initial value of total ground pressure at tunnel axis level, γ*H0. An extreme case of this evolution corresponds to the soft clays subjected to a densification process induced by the abatement of the original hydrostatic pressure in the aquifers that underlie the lacustrine clays, as in the valley of Mexico; in this case, as the piezometric abatement increases, the top of the tunnel liner is subjected to load increases, and at the same time, the sides of the tunnel liner experience a loss of confinement due to reduced water pressure. Pressure differentiation induces important stresses on flexion and compression in the lining (Tamez et al., 1997; Rodríguez et al., 2013).
In this work we study the soil-lining interaction of tunnels built in soft soils subjected to a consolidation process through physical modeling in geotechnical centrifuge, which allows to reproduce the field stresses in a model in a reduced version of the prototype and to accelerate the effects of consolidation phenomena, allowing a considerable reduction in the time scale in relation to the prototype. To obtain long-term stress distribution acting on the support when subjected to piezometric abatement, eight tension cells and five piezometers were installed in the tunnel lining, as well as 16 strain gauges to obtain bending moments and axial forces. In addition, five piezometers were placed in the soil mass at different depths to obtain the magnitude of the piezometric abatement and three surface extensometers to obtain the surface settlements.

BANKING MEMBERS:
Interno - 2517970 - GREGORIO LUIS SILVA ARAUJO
Interno - 2161425 - JUAN FELIX RODRIGUEZ REBOLLEDO
Externo à Instituição - Miguel Angel Cabrera Cabrera
Externo à Instituição - GABRIEL AUVINET GUICHARD - UNAM