干旱区生态环境知识资源中心

The load transfer of bored piles in medium dense cemented sands was examined by field tests at two sites. At the first site, two bored piles were tested in axial tension to failure. One pile was instrumented with strain guages to measure the axial load distribution at all load increments. The results indicate significant load transfer along the pile length. The average shaft resistance measured was 80 and 100 kN/m(2) in medium-dense and very dense, weakly cemented calcareous sand, respectively. At the second site, a tension test was carried out on a bored pile in uncemented cohesionless sand. By comparing the results at the two sites the influence of cementation on the uplift capacity was assessed. The shaft resistance depends on many factors including the relative density, degree of cementation, soil fabric, and method of construction. It increases with the standard penetration test (SPT) N values; however, the SPT is not considered a reliable test for strength characterization of cemented sands. Analysis of the pile capacity can be made considering both components of soil strength, namely, cohesion intercept c and angle of shearing resistance phi.