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Heathrow Express Cofferdam (1994–1995)
Published in Alan Powderham, Tony O’Brien, The Observational Method in Civil Engineering, 2020
In practice, the cofferdam significantly out-performed all of the predictions computed from a wide range of analyses. As discussed below, the measured deflections were more than three times less than those predicted by analysis using the assumptions for MC conditions. The associated movement trend was already very evident at the 7 m depth review and enabled a variety of advantageous design changes to be implemented. The first change was to increase the depth of excavation and liner ring construction from 1 m to 1.2 m. In fact, it was evident from a design perspective, on the basis of the observed performance, that this increase could have been at least 50%. However, the depth of 1.2 m was adopted. At this value, the volume of bulk excavation reached the practical limit for the weekly cycle, noting that these substantial works were being undertaken at the centre of a busy airport which naturally imposed constraints on spoil removal. This change, allowing a faster rate of construction, was undertaken after completion of liner ring 9, all those thereafter being of the increased depth. This reduced the total number of rings from 29 to 22.
The Importance of Geometry for Computer Controlled Segment Erection
Published in Harald Wagner, Alfred Schulter, Tunnel Boring Machines, 2020
After completion of one ring, all thrusters should be released in order to utilize the self regulating behaviour of the ring, getting constraint free segments. This is only possible when thrusters are not being used for face stabilization.
Benzoxazine-epoxy thermosets with smectic phase structures for high thermal conductive materials
Published in Liquid Crystals, 2019
Ying Liu, Sheng Gao, Xinjian Gong, Qingbin Xue, Zaijun Lu
In s-BEI55-255 [Figure 5(d)], the absorption peaks at 1225 cm−1 and 944 cm−1 disappear, indicating the completion of the ring-opening polymerization of BZ monomers. The result of the extraction experiment displays that no soluble substance exists, suggesting the formation of PBZ cross-linked network structure. Figure 6(b) shows the SPM phase image of s-BEI55-255. The purple phase with a higher modulus corresponds to the s-PEI phase while the light green phase with a lower modulus corresponds to the PBZ phase. Obviously, the purple phase and the light green phase distribute crossly, indicating the probable formation of a benzoxazine-epoxy interpenetrating polymer network in s-BEI55-255. Additionally, the microphase separation phenomenon still exists in s-BEI55-255.