Krechowiecki-Shaw C.J.,University of Birmingham |
Jefferson I.,University of Birmingham |
Royal A.,University of Birmingham |
Ghataora G.S.,University of Birmingham |
Alobaidi I.M.,Atkins Ground Engineering
Canadian Geotechnical Journal | Year: 2016
Extraction of resources in remote locations can require temporary haul roads to transport extremely large, slowmoving, indivisible loads (e.g., plant, oil-gas production modules, and reactors, weighing in excess of 1000 t) without interruptions. Poor subgrade soils may experience larger cyclic strains and greater cyclic degradation under these conditions than under conventional roads, yet the short engineering life precludes many foundation-strengthening options due to cost. As there is little research into this unique situation, this paper synthesizes research from a broad range of applications to discuss implications on expected soil response. Reference is made to critical state theory and discrete element method (DEM) modelling to develop fundamental concepts considering particle-scale interactions. Cyclic failure is proposed to be a kinematically unstable process, triggered by shear banding on the Hvorslev surface, tensile liquefaction or fabric-governed meta-stable liquefaction; the latter is particularly influenced by stress history and anisotropy. This paper finds pore-water pressure accumulation under load and dissipation between loads are key to cyclic degradation and furthermore to be dependent upon load duration, principal stress rotation, and repetition frequency. For meta-stable, liquefiable soils in particular, inclination of principal stresses is at least as important in assessing failure risk as magnitude of stresses. © 2016, Canadian Science Publishing. All rights reserved.
Krechowiecki-Shaw C.J.,Atkins Ground Engineering |
Alobaidi I.M.,Atkins Ground Engineering
Construction and Building Materials | Year: 2015
Abstract The UK Department for Transport plans to install 25 kV overhead electrification on existing major routes in Great Britain as part of route modernisation and operational carbon reduction strategies. The design of foundations for railway electrification masts is a particular challenge for geotechnical engineers. Foundations may be required for hundreds or thousands of structures, each with different load and ground conditions. The large number of structures and tight programme timescales mean that site-specific ground investigation and design is not feasible or economic and a set of generic designs must be developed to encompass as much of the inherent variation as possible. This paper proposes a new method for designing laterally loaded piles - which avoids the large number of calculations for specific load cases and focuses instead on underlying system dynamics of vertical and lateral pile resistances and deflections to derive interaction relationships. The methods proposed in this paper can be adapted for use with various formulae and codes of practice to suit the designer's preference, although the focus of this paper is on the use of Eurocode 7. This paper does not propose modification to design formulae but provides a more effective use of these formulae to develop designs. The results are ultimately presented in a series of design charts upon which the allocation engineer can plot applied structural loads to determine a pile's design length for given design criteria. This method yields many benefits: the end product is simple to use, it is able to cope with the large variations in applied loads inherent in electrification schemes, it provides a Eurocode compliant design and the time required to produce these designs is significantly reduced when compared to calculation based on site-specific loads. A particular benefit is that the method can cope more easily with iterations and variations in the assumed loads and system layout that arise during the design process. © 2014 Elsevier Ltd.