Influence of loading rate on pile capacity in unsaturated sand

When in-situ tests are performed to determine the ultimate capacity of a pile after the installation, quite a lot of types of tests are available. The following tests are generally used, in order from most used method to least used method: the static testing method, dynamic testing methods, pseudostatic and statnamic testing methods. During a pseudostatic (or statnamic) test the pile is loaded with a ~ 70-150 ms loading pulse. In comparison with the dynamic test this loading regime is about 20 times as long, in comparison with the static test this is very short lasting. The difference in loading regime is influencing the bearing capacity of the pile. In literature two main phenomena for the change in bearing capacity are recognized: the excess pore pressures and the loading rate. In the typical Dutch situation the end bearing piles are situated in the Pleistocene sand layer, so the influence of the loading rate in non-saturated and saturated sand are of interest. From literature is concluded that the effect of the loading rate on the strength and stiffness properties for dry sand are small, but for the rate effect on the shaft friction no conclusive answer could be found. Therefore a series of model scale tests are performed to investigate the influence of the loading rate on the bearing capacity

De integratie van openbaar vervoer en doelgroepenvervoer in landelijke gebieden in Nederland: Een algemeen toepasbaar evaluatiemodel en case studie in Noord-Limburg

Civil Engineering and GeosciencesTransport & Plannin

On the Modelling of Pile Installation

This thesis introduces two different types of physical model tests to investigate the stress and density change in the soil during installation of a jacked pile as well as two numerical modelling approaches to model the same process in a finite element code capable of large deformations.Geo-EngineeringGeotechnologyCivil Engineering and Geoscience

Optical investigation into the effects of suffusion in a granular medium

The current paper presents a novel experimental method which is able to capture the effects of suffusion by substitution of the fines in a sample by salt of a similar grain size. The setup is tailored to optically capture the change in soil structure behind a glass window in a plane strain strongbox using a digital camera. Subsequently, digital image correlation techniques have been used to quantify the structural change. The first model test shows promosing insight in the pseudo suffusion mechanism. The test setup therefore offers a valuable addition to permeameter tests

Study of literature regarding the fatigue behaviour of unstiffened tubular joints: Part 3 - Stress concentration factors in tubular joints

Civil Engineering and GeosciencesStructural Engineerin

Combined full field stress and strain measurement methods for granular materials

The current paper re-introduces the photoelastic measurement method in experimental geomechanics. A full-field phase stepping polariscope suitable for geomechanical model tests has been developed. Additional constraints on the measurement and mechanical setup arising from geomechanical test conditions are outlined as well as the opportunity to measure the displacement fields in the sample with digital image correlation. The capability of the current setup in retrieving the stress and strain field in a granular material is demonstrated.GeotechnologyCivil Engineering and Geoscience

Multi-dimensional electro-omosis consolidation of clays

Electro-osmosis consolidation is an innovative and effective ground improvement method for soft clays. But electro-osmosis is also a very complicated process, as the mechanical behaviour, and hydraulic and electrical properties of the soil are changing rapidly during the treatment process; this makes electroosmosis hard to describe and simulate. Traditional electro-osmosis consolidation theory cannot provide a satisfactory solution, because it does not directly consider the mechanical behaviour of the soil and the coupling between the soil deformation, electro-osmosis flow and pore pressure. A numerical model for the electro-osmosis consolidation of clay in multi-dimensional domains is presented, with the coupling of the soil mechanical behaviour, pore water transport and electrical fields being considered. Three fully coupled governing equations considering force equilibrium, pore water transport and electrical distribution are presented and solved using COMSOL. The model is verified against the well-known classical analytical solution for electro-osmosis consolidation. A two-dimensional numerical model is then simulated to investigate the settlement and excess pore pressure profile during the electro-osmosis consolidation process. It is found that the peak excess pore pressure is developed near the bottom of the anode and that the maximum settlement is developed near the top of the anode. Moreover, excess pore pressures and settlements develop very rapidly at the beginning of the electro-osmosis treatment, but then become slower with time.Geoscience & EngineeringCivil Engineering and Geoscience

L'Europe: Le nouvel espace public

Paper presented at First Meeting of the Specialist Study Group ‘Media and Communication in Europe’ at the University of Leeds, EU and the public sphere(s), 17-18 November 2006No publicad

Load cell resonance frequency analyser: Frequency analysis system for load cell based conveyor belt weighing systems

In this thesis, the design of a frequency analysis system for conveyor belt weighing systems is designed. The objective of the thesis is to detect a change in resonance frequency, caused by a change of pressure applied to a sensor. The design features a resolution of 10 000 discrete frequency levels in a bandwidth of 0.5 MHz. Noise division of a pseudo random noise (PRN) signal is used to obtain a clear frequency spectrum. An ADC is implemented to digitize an analog input signal. Furthermore, a digital down converter using a CICfilter and CORDIC based controlled digital oscillator is applied. The frequency-domain translation is achieved using an FFT. Lastly, an interpolation over the spectrum is realized to increase the frequency resolution. Additionally, an analytical analysis of the primary noise sources in the system is given. The entire system is simulated in MATLAB to validate the designed blocks.Electrical Engineerin

Development of an instrumented model pile

An instrumented model pile has been realized to study the displacement pile installation effects in sand in physical model tests. The system includes a model pile, instrumented with axial and horizontal contact stress sensors, and a corresponding calibration apparatus. The development of the instrumented model pile, including numerical analysis of the mechanical response during testing, and an optimization of the instrumentation to minimize thermal effects are described. The performance of this new model pile is demonstrated using calibration measurements and an example application in a physical model test at an elevated stress level in the geotechnical centrifuge.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Geo-engineerin