Author : Mahmood Rashid Mahmood and Ahmed Fadhil Faraj

This research is conducted to study the piping phenomena occurs with cohesinless soils below different levels of water with different grain size distribution, (i.e. fine, medium and coarse sand) and its effect when excavation process done within pipe pile through experimental model study. The sand was used as a natural soil in this study, poorly graded clean sand and most particles were rounded. The sandy soil was sieved to obtain different grain size distribution of fine, medium and coarse graded according to (ASTM D 422). Total number of (166) models of steel pipe piles test, involving four open-ended steel pipe piles models of 32 mm in diameter embedded to a depth of 500mm within different grain size distribution cohesionless soils prepared with a different relative densities of (35, 50 and 70)%, under various head of water of (20, 30 and 40) cm above soil surface It was found that the water head increase the ultimate load capacity of piles but when excavate inside the pipe pile, piping phenomena will occur when reaching to a certain length of soil inside the pipe pile. Generally this phenomenon affected by many parameters such as soil density, water head and grain size distribution. The results appeared that the ratio of inside soil column length to the embedded pile length which cause that phenomena in fine sand about (9 – 27) %, while in medium sand piping occurs with percent about (6 – 24)% and for coarse sand the percent about (14 – 26)%.

Keywords: Open pipe pile, piping phenomena in pipe piles, cohesionless soils, grain size distribution

Article published in International Journal of Current Engineering and Technology, Vol.7, No.5 (Sept/Oct 2017)