Rigid columns penetrating a firm underlying stratum have often been used to enhance the stability and improve the settlement of embankments over soft ground. Furthermore, an inclined underlying stratum is commonly encountered in engineering practice. This investigation experimentally and numerically studies the performance of embankments over soft ground reinforced by rigid columns with various embedment depths. In centrifuge tests, a tilting failure occurs for columns with an embedment depth Le of 2D (D is the diameter of columns), whereas the embankments remain stable for Le of 7D. This result indicates that the inclined underlying stratum weakens the restraint effect at the column base and that a greater embedment depth is required to ensure the stability of embankments. Parametric studies numerically reveal that there exists a critical embedment depth, which represents a shift in the failure mechanism. The optimum column layout is determined based on the contributions of columns in different locations beneath an embankment. Finally, the influence of the embedment depth on the distribution of the bending moment of the columns and the soil reaction are discussed.
Larimichthys crocea is a marine fish species cultured in China.Short-term starvation is often applied to improve the quality of cultured L.crocea,and the expression of ghrelin in tissues of stomach,muscle,brain,intestines,liver,and kidney,involved in starvation response,under starvation conditions were studied to understand the effect of starvation on the expression of ghrelin in L.crocea juveniles.The ghrelin expression was tissue-specific,and expression was significantly higher in the stomach compared to other tissues(P0.01).Additionally,ghrelin expression in different tissues changed along with prolongation of fasting.In the stomach,ghrelin expression levels increased gradually at the beginning of the fast,and then declined after eight days of fasting.Gene expression in the brain and intestines increased at the beginning of the fast,and then decreased with longer fasting time.Interestingly,ghrelin expression declined at the beginning of the fast,then increased with longer fasting in the kidneys and muscles.These results suggest that ghrelin is involved in starvation response in L.crocea juveniles.This study provids insights into ghrelin function and an important reference for the development of reasonable feeding strategies for L.crocea juveniles. 相似文献