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The objective of this paper is to explore the gaps in the present analysis methods proposed by various joint industry projects and others for pipeline walking behaviour. Thereafter, present analytical methods are extended to bridge the gap between analytical modelling tools and numerical analysis, by extending analytical models to encompass bi-linear soil friction behaviour. In the analytical solution, the pipe-soil interaction is usually modelled as rigid-plastic, expressed as ultimate resistance per unit length. Often this term is expressed non-dimensionally as a friction factor, µ. However, the elastic-plastic (i.e. bi-linear) behaviour of the soil and the effect of this bi-linear response of the soil on the walking behaviour were not addressed in the literature. The elastic-plastic behaviour is often represented by an additional parameter, specified as the mobilisation displacement. This is defined as the amount of axial displacement that occurs before the ultimate friction is generated, and the resistance rises linearly with displacement up to this value. The walking behaviour is affected by the axial friction mobilisation displacement. The existing analytical solutions are extended to incorporate the elastic-plastic response of the soil into the expression of pipeline walking, supported by a new derivation. Numerical verification with ABAQUS is also provided for the proposed expression.

This paper investigates the effectiveness of the effective area method (EAM) for assessing the undrained load-carrying capacity of rectangular foundations under combined vertical (V), horizontal (H) and moment loading (M) by comparing with finite-element method (FEM) results. Predicted ultimate limit states under combined loading from the two methods are compared and the equivalent rectangle derived from the EAM is compared with the contact region obtained from the FEM. For one-way eccentricity, good agreement in the V-M capacity is achieved with the two methods despite differences between the effective area and actual contact area. However, V-M capacity for two-way eccentricity obtained from the EAM is significantly smaller than that derived from the FEM, with the discrepancy becoming more pronounced with increasing mobilisation of the vertical capacity. V-H-M failure envelopes established by the EAM also fall significantly inside those determined using FEM. The contributing factors for the discrepancies are explored systematically in the paper.

Although it is accepted that the coefficient of consolidation for soil is not a true material property, but reflects the net effect of permeability and compressibility, it is a very useful parameter in day to day design. Design calculations make extensive use of elastic solutions for consolidation, such as beneath a shallow foundation or around a driven pile, but an important consideration is how to measure or estimate an appropriate coefficient of consolidation to use in those solutions. Typically the quantity is determined either from laboratory oedometer tests (generally then referred to as cv) or from field dissipation tests using a piezocone or piezoball penetrometer (generally then referred to as ch). Since the latter form of test includes a mix of stress paths, for some of which the soil has a stiffness associated with unloading and others of which involve plastic compression, the magnitude of ch for a given soil is typically 3 to 10 times the value of cv from virgin compression in laboratory oedometer tests. The paper explores the relationship between cv and ch for different boundary value problems, within the confines of soil modelled as Modified Cam Clay, for both isotropic and anisotropic permeability. Problems range among: simulated oedometer testing, field dissipation testing and pore pressure response beneath a shallow foundation. Results of finite element analysis of this range of problems are used to develop guidelines for different classes of problem, comparing the relevant coefficient of consolidation against a benchmark cv value associated with virgin compression in an oedometer. The normalised values of consolidation coefficient are expressed as functions of fundamental soil parameters used within Modified Cam Clay.

Advances in photonics have stimulated significant progress in medicine, with many techniques now in routine clinical use. However, the finite depth of light penetration in tissue is a serious constraint to clinical utility. Here we show implantable light-delivery devices made of bio-derived or biocompatible, and biodegradable polymers. In contrast to conventional optical fibres, which must be removed from the body soon after use, the biodegradable and biocompatible waveguides may be used for long-term light delivery and need not be removed as they are gradually resorbed by the tissue. As proof of concept, we demonstrate this paradigm-shifting approach for photochemical tissue bonding (PTB). Using comb-shaped planar waveguides, we achieve a full thickness (>10 mm) wound closure of porcine skin, which represents ~10-fold extension of the tissue area achieved with conventional PTB. The results point to a new direction in photomedicine for using light in deep tissues., National Institutes of Health (U.S.) (R21EB013761), National Institutes of Health (U.S.) (P41EB015903), National Institutes of Health (U.S.) (R01CA192878), United States. Dept. of Defense (FA9550-13-1-0068), Bullock-Wellman Fellowship, Marie Curie International Fellowship (Career Integration Grant 631679), Seventh Framework Programme (European Commission) (Marie Curie International Outgoing Fellowship Grant 627274), Human Frontier Science Program (Strasbourg, France) (Young Investigator Grant RGY0074/2013), National Research Foundation of Korea. Bio & Medical Technology Development Program (2012M3A9C6049791), Korea (South). Ministry of Knowledge Economy (National IT Industry Promotion Agency IITP-2015-R0346-15-1007)