THE EFFECT OF STANDARD WAVE CONDITIONS ON DRY SUIT INSULATION WHEN MEASURED ON HUMANS
Testing of immersion suits is commonly conducted in calm or circulatory water. Several investigators have argued that this is an unrealistic test for a suit that is designed to protect a human from hypothermia in open ocean conditions. In support of this argument, Steinman et al. (1) and Romet et al.(2) reported a significant reduction of suit insulation in turbulent water when compared to still water by an average of about 30% when measured on humans. Such differences were found for loose-fitting wet suits but were not investigated for dry suits. Recently, Sowood et al. (3) reported a reduction of dry suit insulation by about 30% in turbulent water (wave height of 60 cm) compared to still water when tested on a thermal manikin.
Immersion hypothermia: comparative protection of anti-exposure garments in calm versus rough seas.
To evaluate the thermal performance of anti-exposure garments in rough seas, eight garment-ensembles were studied: 7 foam-insulated garments (2 tight-fitting "wet" suits, 3 loose-fitting "wet" garments, 2 "dry" suits) and 1 uninsulated, loose-fitting control. Mean calm and rough water temperatures were 10.7 and 11.1 degrees C, respectively. Rectal temperature, back skin temperature, heart rate, and subjective evaluations of garment protection were measured. Loose-fitting, "wet" garments allowed significantly greater (approximately 50-100%) mean rectal temperature cooling rates and significantly larger declines in skin temperature in rough water than in calm water. Such differences were not found for either the tight-fitting "wet" suits or the "dry" suits. Heart rates were significantly higher in rough seas than in calm seas for all garments. Rectal and skin temperature changes were positively correlated with each other and with subjective evaluation of cold water flushing; they were negatively correlated with warmth and tightness-of-fit. "Dry" garments provided better protection than did "wet" garments in both sea conditions, and tight-fitting "wet" garments provided better protection than did loose-fitting "wet" garments in rough but not in calm seas. Accidental immersion in rough seas may be associated with significantly lower survival times than previously estimated from calm-water studies.
Centrifuge modelling of effects of shield tunnels on existing tunnels in soft clay
With the rapid development of the subway network,the phenomena of shield tunnels going across the adjacent tunnels are becoming more and more common.The interaction between shield tunneling and nearby tunnels is more complicated than the ordinary shield tunneling in intact soil strata.Based on the project of Shanghai Bund Passage crossing Metro Line 2,the method of centrifuge modeling together with the field measurement is employed to study the effects shield tunneling on nearby strata and existing tunnels.In centrifugal model tests,the effects simulation techniques considering the unloading of excavation,ground loss and grouting are developed to analyze the longitudinal settlement of the shield tunnel and the existing tunnel induced by the shield tunneling.Besides,the deformation distribution and settlement curves of the existing tunnels during shield construction are studied by using the monitoring data.