Cavity Effects on Axially Loaded Single Pipe Piles Embedded in a Sand Deposit

A soil column that enter the tube hall when the pile advances through sand layer that form a column of soil through pile tube is well known as the (soil plug), while the piles driving process into the soil, so during this process of pile penetration. A frictional forces-resistant which induced through the inner tube walls and the soil inside the tube can be established and achieve a certain value to avoid further soil intrusion into the pile tube. A small scale cavity were preformed adjacent to the tube of pile at specified locations which located horizontally with a distance between the pile center and cavity center which defined as (X) and depth of cavity measured from the surface of soil by (Y) which mean cavity depth with variation in location of cavity for all laboratory tests had been studied. The pile bearing capacity was investigated with the presence of cavity. It was concluded in case of single pile that the removal of soil plug as (plug removed 100 %) cause severe decreasing in pile capacity specially when the cavity located close to the pile. The percent of reduction reach to 90 % loss in single pressed pile ultimate capacity and may reach to about 84% for single pile with driven open ended shape. The most effective location of cavity in horizontal datum was at (X /D= 1.5) that gives clear reduction in the load capacity, also the same for each datum in vertical direction such as (Y/L=0.5, 0.833, 1 and 1.2), while the massive reduction is achieved if cavity location directly beneath pile end (X/D=0).