THE BEHAVIOUR OF MODEL SCREW PILES IN COHESIVE SOILS

Abstract

Anchors are being extensively used in foundations for the structures subjected to both compressive and tensile forces. An attempt has been made to develop screw piles as anchors in clayey soils. The screw piles are made of hollow galvanized iron pipes (dia. 25mm, 44mm, 60mm and length 640mm and 1000mm) to which helical plates (dia. 75mm, 100mm, 150mm) are welded. Number of plates are varied from 2 to 4 and there are different spacings of these plates adopted. These piles are screwed into soft to medium stiff clay bed prepared in a test tank. Standard type of loading frames have been made for effecting both compressive and tensile forces. In all about 40 Nos. of tests have been conducted in three soils. The behaviour of these piles has been studied through the load deformation curves. Decrease in the moisture contents leads to significant increases in the capacity of the piles. By keeping the ratio of the spacing of the helical plates to diameter of the helical plates between 1.0 and 1.5, optimum capacities of the piles could be obtained. The test results indicate that theoretical predictions for the load carrying capacities can be made by making use of the measured shear strength of the soils.