Experimental study on vertical bearing characteristics of a single pile in cemented calcareous sand layers

According to the cemented geological status of calcareous sand layers, a series of indoor model tests was performed to study the behaviors of the steel pipe pile in the cemented calcareous sand layers such as bearing capacity, the settlement, and compared with uncemented calcareous sand. The results show that the influence of relative density on bearing capacity of the pipe pile in cemented calcareous sand layers is obviously weakened compared with that in the uncemented layers. The bearing form of the pile still presents as an end-bearing pile, and the bearing ratio of pile tip resistance becomes higher and higher with the increase of cementation degree of calcareous sand. In highly cemented calcareous sand layers, there is an asynchronous process in the development of side friction of the pile. This is because when the pile foundation settles, the lower part of the pile shaft destroys the sand layer to form a tighter new contact surface, which is more sensitive to the radial expansion of the pile body. The side friction of the pile in cemented calcareous sand layers has no obvious hardening stage in the q(s) - S-u curve of pile in cemented calcareous sand, and different from the multi-segment broken line of the q(s) - S-u curve of the pile in uncemented calcareous sand, the q(s) - S-u curve of the pile in cemented calcareous sand is closer to a hyperbolic curve.