Use of bag-sealed bored pile in Karst areas

Abstract

Casting bored piles in Karst areas is often problematic, since the concrete can penetrate through cave systems or underground stream channels, resulting in poor construction quality of bored piles with insufficient bearing capacity. A new type of bored pile is proposed to cast the concrete within a rubber/geotextile bag in the bored hole, which can restrict the loss of concrete through stream channels in Karst areas. In this study, model-scale laboratory tests were conducted to assess the feasibility of casting rubber/geotextile bag-sealed bored pile and to evaluate its bearing behavior. The measured results for a bag-sealed pile within Karst regions and a normal pile with equal diameter in a uniform ground without stream channels were compared. It demonstrates that casting bored pile within a big is an effective solution to increase the bearing capacity of pile under static loads. The ultimate bearing capacity of bag-sealed pile is about 1.5 times that of equal-diameter pile. The settlement of bag-sealed pile is much smaller than that obtained for equal-diameter pile under the same loading conditions.