Estimation of ultimate load for a screw pile under the vertical pressure

The load displacement curve of screw pile usually shows the characteristic of multiple inflection points and discontinuation, therefore it is difficult to determine the ultimate load or its physical implications. The static loading tests on three types of screw pile foundations were conducted in this study. In the test, 12 P-s curves were obtained to analyse the pile-soil interaction and the loading characteristics under vertical static loads. In addition, the ultimate load of screw pile under vertical loads was estimated using Log P-s method. Also, the study investigated the load capacity characteristic from the aspect of the soil compactness and RDD (the ratio of laminas distance to the net radius of lamina). After the soil between laminas was compacted, the P-s curves became smooth. With the increase of its ultimate load, the pile head settlements became slow. The ultimate load and settlement increased with RDD increase.