Model studies on effect of pseudo-rock-socket strength on resistance of friction-only piles

Abstract

1-g small scale model experimental investigations were carried out in the laboratory to study the behavior of piles, socketed in rock, under axial load. In this study, an attempt is made to investigate the mechanics of load distribution by friction on model piles made of Aluminum tubes, socketed in pseudo-rock samples. A series of rock socketed model pile load tests was carried out using the indigenously developed loading frame and set-up. Two Aluminum tube piles having outer diameter of 60 and 80 mm were used in the investigations. Different length-to-diameter ratios were considered by changing length of piles. Sponge was provided at the tip of the model pile to avoid the influence of end resistance and to create skin frictional resistance only. Different mixes of pseudo-rock specimens were prepared by varying the proportions of cement and plaster of Paris. Uniaxial compression strength tests were conducted on the pseudo-rock specimens to evaluate the effect of strength of pseudo-rock specimens on skin friction. Also, elastic constants (modulus of elasticity and Poisson ratio) and shear parameters (cohesion and angle of internal friction) of pseudo-rock specimens were determined. Experimental results show that the load-settlement curve is nonlinear for axial compression load tests. An empirical relationship is established between compressive strength of pseudo-rock and maximum skin friction mobilised in the socketed portion of pile. The experimental results and the results obtained by using empirical equations suggested by other investigators are compared and a good correlation is observed.