Experimental investigation of settlement in sand soil of jacked pile subjected by vertical compressive cyclic loading

Abstract

Repeated-variable external effects must be properly evaluated when solving many geotechnical engineering problems. Cyclic loads of different intensities is caused by technological and environmental effects, e.g. traffic, industrial machinery, wind, waves and snow. The influence to the investigated system (structure, ground) and usually is analyzed applying static or dynamic models. Low cycle load model is relevant to response of analyzed system, where inertia forces do not contribute essentially to it's behavior. In this case the effects of coupling plays the dominate role to the system response measures. The incremental deformation of ground (e.g. in terms of settlements of foundations) caused by cyclic nature of separate loads for buildings, where constant (weight) loads dominate versus variable loads is the case where dynamic response analysis is not necessary (low cycle case). Here static analysis is sufficient, but static response measures should involve parameters of loading process, consisting from constant and variable loads. The peculiarities of ground state changes (densification, yielding, etc.) prescribing foundation response range (elastic, elastic-plastic, etc.) should be taken into account. The experimental study for displacement (jacked) pile settlement in sand soil evaluation has been performed. The model pile has been tested for 5 different dead and variable load components. 50 load variation loading cycles have been applied, pile top displacements (id. est. ground settlements, as axial deformation of pile is negligible) versus number loading cycles measured. Peculiarities of settlement development versus different loading conditions have been reported.