Centrifuge Modelling of Long-term Tunnelling Ground Movements

The increasing demand for public transport provision in cities has resulted in a requirement for enlarged public transport infrastructure. Where underground railways represent an important component of these systems, tunnel construction will inevitably lead to some degree of ground movement that can cause damage to surface structures and buried structures and services. It is important, therefore, that in the design of tunnels in urban environments these ground movements are predicted reliably. Predicting short-term ground movements resulting from tunnelling is standard when assessing the potential for damage to adjacent infrastructure. However, long-term tunnelling-induced ground movements and how these develop are understood less well and a research programme, based on geotechnical centrifuge modelling, is being conducted to improve our fundamental scientific understanding of this. The first stage of the programme has been to develop an apparatus that simulates the construction of a tunnel with a lining of known stiffness and permeability and allows construction ground loss to be replicated correctly. This paper describes the initial development of the apparatus along with results and analysis that demonstrates the suitability of the technique for the proposed study. The results obtained were observed to represent the short-term settlements that might be expected above a tunnel excavated in clay. The results also prove the modelling technique suitable for application in a full parametric study in which the geometry and boundary conditions of the model will be varied together with the permeability of the tunnel liner

A low-cost miniature immersible pore water pressure transducer

The ability to measure pore water pressure accurately in geotechnical models is vital for allowing researchers to quantify effective stress and, frequently, its temporal variation. The earliest use of electrical devices to measure pore water pressure in specific locations within a model employed a standard laboratory pressure transducer located outside the boundaries of the model connected to tubing inserted into the model. However, this technique was superseded by the development (some 40 years ago) of submersible miniature pore water pressure measuring devices that could be located within a model to measure pore pressure directly at specified locations. In particular, miniaturisation allowed these transducers to be used in small scale centrifuge models. This facilitated, across the full spectrum of geotechnical engineering modelling, both enhanced understanding of mechanisms, by permitting quantitative analysis, and validation of numerical techniques. The earliest miniature transducers, the PDCR81 device manufactured by Druck, rapidly became universally adopted by the geotechnical modelling community. The production of this device was halted about 10 years ago, but other manufacturers have developed similar miniature pore water pressure transducers. Whilst the newer devices have been demonstrated to be effective their unit cost is relatively expensive; owing to the low volume of manufacture. This can result in forced limitations in the number that may be in a model, or a reluctance to use them in zones of models where they might be damaged. The requirement for a cheaper but equally reliable device prompted the work described in this paper. This is now achievable because of the development for the consumer market of a mass produced robust, immersible pressure device that has a very low unit cost. The paper will describe the development of a miniature transducer, employing this device, that can be located within models in a similar way to the PDCR81

Age-related chances of mitochondrial cytochrome C oxidase and F(0)F(1)-ATP synthase subunit contents in rat cerebral cortex

The levels of subunits I, II/III, and IV of cytochrome c oxidase and of subunits alpha. beta and gamma of F(0)F(1)-ATP synthase in inner mitochondrial membrane proteins purified from cerebral cortex of rat at 2, 6, 12, 18, 24, 26 months of age were analyzed by Western blot. Age-related changes in the content of subunits, encoded either in mitochondrial or nuclear DNA, were observe

Changes of mitochondrial cytochrome c oxidase and FoF1 ATP synthase subunits in rat cerebral cortex during aging

The contents of subunits I, II/III, and IV of cytochrome c oxidase and of subunits alpha, beta and gamma of FoF1 ATP synthase in inner mitochondrial membrane proteins purified from cerebral cortex of rat at 2, 6, 12, 18, 24, and 26 months of age were analyzed by western blot. Age-related changes in the content of subunits, either of mitochondrial or nuclear origin, were observed. All the cytochrome c oxidase (COX) subunits examined showed an age-related increase from 2-month-old rats up to 24 months with a decrease at the oldest age (26 months). The same pattern of age-dependent changes was observed for gamma ATP synthase, while the alpha and beta subunits increased progressively up to 26 month