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Negative skin friction developed on the pile surface causes many problems when piles are built in fully saturated clay. In this work, a study of NSF on a square cross-section pile corresponding to the circular pile circumference was developed. The pile was modeled as a concrete element, embedded and fully contacted with fully saturated soft clay. The clay layer is supported on a sand layer as a sub-base using ABAQUS software, and the NSF was developed on piles due to the consolidation of the clay over a 5-year period. A square pile has been found to provide lower NSF values than a round pile. Then, for the first investigation, both piles were loaded with lateral loads at the top to investigate the effect of the horizontal load on the NSF values, as there is no literature or study done on this point. The results emphasized that lateral loads reduce the NSF developed on piles. A parametric study was performed to investigate the parameters affecting the NSF values induced on piles, such as soil permeability, ballast, and lateral load values. It was concluded that square piles provide better NSF values than round piles for both single piles and pile groups. Doi: 10.28991/CEJ-2022-08-10-08 Full Text: PDF

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This study summarizes the evaluation of the pile static load test as a tool for the prediction of pile behavior in clayey soils. The pile and soil cases were modeled by three different constitutive models; Mohr-Columb (M-C), Hardening Soil (HS), and Soft Soil Creep (SSC). The static loading test scenarios were also numerically modeled to study the pile behavior. The models were analyzed by using numerical finite elements software (PLAXIS 3D Foundation). A construction site located in Mansoura, Dakahleya Governorate, EGYPT, was selected to perform the field tests. In order to simulate the soil in the numerical models, two borings with depth of 25 m were carried out to investigate the soil properties in the same site where field static pile load tests are performed later. The pile capacity and settlement were calculated theoretically for each case by using both Egyptian Code formula and numerical constitutive models. The load test was simulated twice for each pile. The first simulates the standard static load test while the second simulates the real-life loading. The results showed that the pile behavior obtained by standard static load test was extremely exaggerated. A modified quick static load test method was proposed and verified. Also it has been proved that, the Modified Quick Load Test (MQLT) method can be used as an alternative method to the classical static load test method.

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