Field tests of laterally loaded flexible piles in soil with top cement-treated layers

Abstract

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.