Rigid containment walls for liquefaction remediation

Many typical ground improvement techniques that are used for liquefaction remediation, such as in situ densification, are not appropriate for application under existing buildings and more novel techniques are required. This paper describes centrifuge tests investigating the performance of rigid containment walls as a liquefaction remediation method. A simple frame structure, founded on a deep layer of loose, liquefiable sand was tested under earthquake shaking. Centrifuge tests were then carried out with containment walls around the base of the structure, extending through the full depth of the liquefiable layer and also partial depth. It is found that rigid containment walls can be very effective in reducing structural settlements primarily by preventing lateral movement of the foundation sand but the impermeability of the walls may also be important. Improvements in structural settlement are observed even when the walls do not extend through the full depth of the liquefiable layer, if the depth of the walls is greater than the depth of the free field liquefaction. In addition, it is found that the accelerations of the structure are not increased, provided there is no rigid, structural connection between the structure and the containment walls. © 2012 World Scientific Publishing Company.

Geomembrane containment walls for liquefaction remediation

Ground improvement techniques can be adopted to prevent existing buildings built on liquefiable soils sustaining damage in future earthquakes. Impermeable geomembrane containment walls may be an economic and successful technique but their design and performance are currently not well defined or well understood for this application. This paper describes centrifuge testing carried out to investigate the performance of such containment walls as a liquefaction remediation method for a single degree of freedom frame structure. The results were compared with those from similar centrifuge testing carried out with the same structure founded on unimproved sand, to assess the effectiveness of the remediation method. It was found that the geomembrane containment walls tested were effective at reducing structural settlement and did not significantly increase the accelerations transmitted to the structure. Structural settlements were reduced primarily by mobilising hoop stress and preventing lateral soil movement. By preventing surface drainage, a decrease in the volume change of the foundation sand was also observed. In addition, the impermeability of the walls may be important as this prevented rapid migration of pore water fromthe free field to the foundation region.

Progress in the evaluation of transgenic fish for possible ecological risk and its containment strategies

Genetically improved transgenic fish possess many beneficial economic traits; however, the commercial aquaculture of transgenic fish has not been performed till date. One of the major reasons for this is the possible ecological risk associated with the escape or release of the transgenic fish. Using a growth hormone transgenic fish with rapid growth characteristics as a subject, this paper analyzes the following: the essence of the potential ecological risks posed by transgenic fish; ecological risk in the current situation due to transgenic fish via one-factor phenotypic and fitness analysis, and mathematical model deduction. Then, it expounds new ideas and the latest findings using an artificially simulated ecosystem for the evaluation of the ecological risks posed by transgenic fish. Further, the study comments on the strategies and principles of controlling these ecological risks by using a triplold approach. Based on these results, we propose that ecological risk evaluation and prevention strategies are indispensable important components and should be accompanied with breeding research in order to provide enlightments for transgenic fish breeding, evaluation of the ecological risks posed by transgenic fish, and development of containment strategies against the risks.

Fatigue performance of aircraft panels with novel skin buckling containment features

To increase structural efficiency of stiffened panels in an aircraft, it is plausible to introduce skin buckling containment features to increase the local skin stability and thus static strength performance. Introducing buckling containment features may also significantly influence the fatigue crack growth performance of the stiffened panel. This study focuses on the experimental demonstration of panel durability with skin bay buckling containment features. Through a series of fatigue crack growth tests on integrally machined aluminium alloy stiffened panels, the potential to simultaneously improve static strength performance and crack propagation behaviour is demonstrated. The introduction of prismatic buckling containment features which have yielded significant static strength performance gains have herein demonstrated potential fatigue life gains of up to + 63 per cent.