Geotechnical site characterization and study of an erosion process caused by urban setting / Investigação geotécnica e estudo de um processo erosivo causado por ocupação urbana

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

This dissertation presents geotechnical site characterization results of an erosion process area, in Bauru city, inland of São Paulo State, Brazil. The objective is to characterize the local soil and define the major causing factors for the erosion process evolution, which initiated with deforestation, soil sealing and discharge of pluvial and sewer water. The erosion turned huge with an urban setting with inappropriate design and no drainage infrastructure jobs. This phenomenon was studied by field observation, in situ and laboratory tests to establish a mechanism to explain the erosion process. Young residual soils of sandstone, mature residual soil weathered by pedogenetic processes and transported soils occur in the site. Characterization, erodibility and mechanical tests were carried out on three typical and distinct soils as well as SPT and CPT testing. The soils were classified as clayey sand with variable colors, almost always in unsaturated condition. Erodibility test results from three different methods classified the soils as very high erodibility, and Nogami and Villibor (1979) method was the most interesting for the studied soil. Suction plays an important role in the shear strength and soil saturation significantly reduced cohesion. Water is the trigging agent and the major responsible for the erosive process evolution, even by superficial or groundwater flow. The flow inside the soil mass changes the grain size distribution of the soil and also modifies their properties. The evolution mechanism begins increasing the soil water content by the rain and it can, in some places, reach soil saturation reducing shear strength turning cohesion equal to zero. Since the soil is saturated and with water flow, it can loose its structure by piping, so its easily detached and dragged along causing slope instability and evolution of erosion process.

ASSUNTO(S)

caracterização mecanismo de evolução erosion process characterization processos erosivos evolution mechanism

ACESSO AO ARTIGO

Documentos Relacionados