Experimental study on piles with pile cap at varying position under different loading conditions

Abstract

High rise buildings and offshore structures are usually constructed over foundation which comprises of several number of piles connected together using pile cap. These piles and pile caps frequently are subjected to a mixture of lateral, vertical as well as twisting forces. Conventional method tends to emphasis predominantly on foundation resistance under vertical loading. The piles are essential subjected to horizontal loads along with vertical loads. Resistance to the vertical and the lateral loading is generally provided by base and side friction, pile-soil-pile cap interaction between pile and surrounding soil, position of the pile cap, number of piles and piles arrangement with respect to the loading direction. In this study, the piles are placed in the sand with pile cap i) above the soil surface at a height of 35mm ii) pile cap bottom resting on surface of soil medium iii) pile cap top placed at the surface of soil and iv) pile cap placed below soil surface to a depth of about 35mm. Experimental analysis were carried out for all the above cases under vertical, lateral and combined loading conditions. Parameters like position of the pile cap, quantity of piles and their arrangements were varied and analysed. The test results reveal that the pile cap placed below the soil surface increases lateral resistance capacity of the piles in the range of 56% to 66% compared with pile cap placed above the soil surface under both independent and combined loading conditions in cohesionless soil.