Mechanical behavior of urban solid waste

Author(s)

Miriam de Fátima Carvalho

• Document type: Doctoral Thesis
• Press: São Carlos.
• Institution: Universidade de São Paulo (USP). Escola de Engenharia de São Carlos (EESC/SBD)
• Defense date: 1999-10-27

Examining board members

Orêncio Monje Vilar; Nélio Gaioto; José Fernando Thomé Jucá; Cláudio Michel Nahas; Jurandyr Povinelli

• Advisor: Orêncio Monje Vilar

Abstract

This thesis deals with the mechanical behavior of urban solid waste from Bandeirantes sanitary landfill (São Paulo, Brazil). Field and laboratory tests, as well as data from field instrumentation (settlement) were obtained and used in the analysis. Results of in situ tests such as standard penetration test (SPT), cone penetration test (CPT), infiltration tests, auger boring for sampling, cross-hole test and electric resistivity are presented and discussed focusing on the difficulties in performing them as well as their potential as a source of design parameters. Laboratory tests were performed using remolded samples collected in two boreholes about 30 m in depth. The waste is about 15 years old and physical and chemical tests showed that about 50% of it is composed of organic past with low values of COD and TDS, which denote that it is degraded to a large extent. Shear strength of waste was studied by means of consolidated-drained (CD) and consolidated-undrained (CU) triaxial compression tests on large specimens, tested both at natural water content and saturated. It is shown that shear strength properties are largely dependent on deformation, since no peak or ultimate value was achieved on stress-strain curves. The values obtained are in accordance with some of the few results available in the literature, either from laboratory and back analysis. Confined compression tests carried out on large samples (385 mm diameter) showed quick initial and primary consolidation and large secondary compression. This in accordance with the field behavior, although in this case secondary compression seems to be composed of two parts: the first, related to the early stages of the fill and second one, which seems to be commanded mainly by chemical and biological degradation. (AU)