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Evaluation of the Collapsibility of Soils in the Semiarid Region of Pernambuco, Brazil

2014; Volume: 8; Issue: 10 Linguagem: Inglês

10.17265/1934-7359/2014.10.010

1934-7359

Sílvio Romero de Melo Ferreira, Stela Fucale,

Soil Management and Crop Yield

Some unsaturated soils may undergo volumetric changes when submitted to an increase in its water content or are inundated under applied loads.This behavior is related to the volumetric instability when the water content is changed.Natural collapsible soils in Brazil are generally found in alluvial, colluvial and residual soils.There are known occurrences of natural collapsible soils in many states of Brasil.In the last two decades, many public projects have been developed in areas where the occurrence of collapsible soils has been associated to geotechnical problems.The present paper devoted to study the collapsible soils in the state of Pernambuco which has been associated with large engineering projects such as housing and irrigation canals.The geotechnical investigation program included test with a field apparatus, called Expanso-colapsometer, which allows the measurement of the field settlements of a small 0.10 m of diameter plate inserted at any depth inside an auger boring hole.Reconnaissance borings with SPT (standard penetration test), investigation pits with undisturbed block sampling and disturbed samples for laboratory tests were also made in order to assess the type and characteristics of the soil.Field tests used the Expanso-colapsometer to measure the settlement of the soil in selected depths under controlled flooding.Laboratory work included double and standard oedometer tests with a controlled rate of water inflow of 1.0 mL/s.It was found that the volume change of the soils when flooded depends on their natural stress state (vertical stress, suction head and structure of soil).