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Item type:Publication, Access status: without files , Numerical model to predict the displacement of piles under cyclic lateral loading using a new hypoplastic spring element(2018-09); ; A numerical model to predict the displacement of piles under cyclic lateral loading using a new type of spring element is demonstrated. The formulation of the numerical model is based on the subgrade reaction method and allows for modelling of a limited number of cycles. To accurately represent the soil behaviour, the spring elements are established on a hypoplastic formulation. Thereby, important soil properties like barotropy, pycnotropy and directionality are captured. Input parameters are determined by laboratory tests and correlations from literature. Performance of the new approach is demonstrated and the results are compared to Finite-Element-Analyses and current standards.Publicationtype: Journal Article306 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , About the influence of one-way loading on the bearing behaviour of precast concrete piles for onshore wind energy plants(2017-03-01); ; ; ; About the influence of one-way loading on the bearing be haviour of precast concrete piles for onshore wind energy plants. Due to the energy transition several wind energy plants are built. Precast impact driven concrete piles represent one option to realise foundation piles onshore. In Germany, the bearing capacity of these piles can be estimated using empirical values taken from current standards or using in-house specifications of plant producers. Cyclic loading of such foundations exceeding 20 [%] of the static characteristic pile bearing capacity have to be considered when estimating the pile bearing capacity. However, the consequences of cyclic loading for the bearing behaviour of precast impact driven concrete piles are not fully understood yet. Therefore, field tests in cohesive and non-cohesive soils considering static and cyclic loading with different load amplitudes have been conducted and are presented within this paper. Using prevalent methods stated in current standards to estimate the bearing capacity of piles under static and cyclic loading are applied to recalculate the results of the field tests. Thereby, the suitability of these methods for estimation of the bearing behaviour of precast impact driven concrete piles under static and cyclic loading is reviewed.Publicationtype: Journal Article121 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Interpretation of CPT data for pile loading behavior - Inverse estimation of void ratio over depth(Australian Geomechanics Society, 2016); ; ; Cone penetration tests are often used for geotechnical site investigation before pile installation. Usually the measured data for cone and shaft resistance are roughly interpreted and applied for the design of the pile resistance. This paper presents an approach for soil modelling included in numerical simulations of pile loading behavior which employs the CPT data directly. Considering the material properties to be known, e.g. from laboratory tests which have been performed on bore hole excavations, state variables such as void ratio distribution and in situ stress state need to be determined to model an accurate initial state. This paper proposes an inverse determination of these unknown variables with mathematical optimization using an evolutionary algorithm to minimize the difference between measured CPT data and simulation results obtained from FEM. The obtained initial state variable distribution for void ratio for a given stress state may then be used to simulate the pile loading behavior without the need of prior interpretation of CPT data. The solution of the proposed inverse problem will be compared to the determination of state variables for a fictitious problem, in which the initial state is known.Publicationtype: Conference Paper49