The knowledge of soil characterization parameters allows identification and classification of materials. Also, indicates the soil behavior in front of stress and deformation. The aim of this paper was to evaluate the methods available for determining the liquid limit by the Casagrande device and Fall Cone equipment. The classic method of Casagrande was developed by Arthur Casagrande in 1932 and the Swedish Fall Cone was developed by Geotechnical Commission of the Swedish State Railways in 1915. To guarantee the representativeness of the evaluation, 31 Brazilian soil samples from different origins were tested (marine, residual, colluvium and tailings). In order to understand the behavior of the samples and evaluate the applicability of the Swedish Fall Cone method were determined other geotechnical properties as a percentage of fines, specific gravity and plastic limit. The results show that the values obtained with the Casagrande method are slightly lower than with the Fall Cone equipment. It was observed a coherent correlation between the methods for liquid limits values less than 80 % with a corresponding coefficient of determination R 2 of 0,9453. Above this moisture content, it was not possible to verify any correlations between the methods applied.
A series of laterally loaded tests on flexible piles inserted in bonded residual soil was conducted. To evaluate the main aspects of shaft mobilisation under lateral loading, a series of tests was performed under two different pile configurations: in naturally bonded residual soil and in artificially top cemented sand layers reinforcing the naturally bonded residual soil. The length to diameter ratio (L/D) of the piles was selected as 20, representing the behaviour of a free-headed, flexible pile. The size of the cylindrical cement-treated sand layers around the pile ranged from 2 D to 4 D and 0·1 L to 0·3 L. The treated layer was a mixture of Osório sand and early-strength Portland cement. Experimental results showed a significant increase in the lateral load performance of flexible piles when the top soil layer was treated with cement. The ultimate lateral load capacity (Hult) increased six fold – from about 50 kN in naturally bonded residual soil to around 300 kN in artificially cemented sand layers embedded in naturally bonded residual soil, and a considerable reduction of the displacements measured at the pile head was observed.
A set of crosswise-loaded flexible piles was tested in binder stabilised top sand layers embedded in lightly bonded residual soil. Slope indicators were used to measure horizontal displacements in free-headed flexible piles during all loading stages. The geometry of the cement stabilised top sand layer surrounding the piles varied from about 2 to 4 times the pile diameter and 0.1 to 0.3 times the pile length. Experimental outcomes present an important enhancement in the performance of the flexible piles under transverse load when a cement stabilised sand layer replaces top residual soil, increasing bearing capacity and reducing maximum horizontal displacements at any given working load. At large horizontal displacements (close to failure), a linear relation is observed between the lateral load and the total lateral area compressing the natural soil around the pile. This evidence helps identifying the pile-soil interaction mechanism and provides sound normalization for test results, both considered necessary steps towards the development of a design concept for predicting lateral pile response.
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