Influence of the penetration of adjacent X-section cast-in-place concrete (XCC) pile on the existing XCC pile in sand

A series of small-scale 1g X-section cast-in-place concrete (XCC) pile-penetration model tests were conducted to study the effects of soil density and pile geometry on the lateral responses of an existing pile and the variations in surrounding soil stress. The results showed that the bending patterns of existing XCC piles varied with penetration depth. The lateral response of the existing pile was sensitive to the change in relative density and pile geometry. For example, the bending moment of the existing pile increased along with these parameters. The development of the radial stress σ′r/σ′v0 of the soil around an existing pile showed different trends at various depths during the penetration of the adjacent pile. Moreover, the change in radial stress during the penetration of the XCC pile did not exhibit the “h/R effect” that was observed in the free-field soil, due to the shielding effect of the existing piles. The peak value of radial stress σ′r_max/σ′v0 decreased exponentially as the radial distance r/R increased. The attenuation of σ′r_max/σ′v0 with r/R in the loose sand was faster than in the medium-dense or dense sands. The σ′r_max/σ′v0 at the same soil location increased with the cross-section geometry parameter.