Elasto-plastic modeling of soft soil considering degradation of stiffness

The stiffness has a large influence on the behavior of soils. Its value is affected by some of the soils properties, such as the over consolidated ratio(OCR), the effective normal stress, and the plasticity index etc. In this paper, the numerical modeling of soft soils was carried out using an improved elasto-plastic S-clay1 model accounting for degradation of stiffness. The relation between the stiffness and the shear strain was established based on a large number of experimental data. The effects of strain-dependent stiffness of normally consolidated soils and over consolidated soils on the stress-strain behavior were studied through a comparison of the simulations with the experimental results of undrained triaxial compression tests. The results show that the behaviors of soils can be well predicted with the improved constitutive model, particularly before the peak stress.     

玻璃钢双体游艇结构可靠度设计

可靠度设计可以较为真实地反映结构安全状态，现已成为结构设计的重点方法之一。本文以一艘玻璃钢双体游艇为例，通过频域水动力分析确定其最危险航行工况，进而对研究对象进行结构应力分析与可靠度计算。在满足可靠度安全要求的基础上，通过改变艇体铺层厚度对双体游艇进行轻量化设计。设计结果显示轻量化效果达到29.1%，优化设计结果良好。该种基于可靠度的设计方法对复合材料船艇结构设计具有一定的参考价值。     

在役双层海底管道试压难点分析

针对生产期间的双层海管试压工期长、油田关停损失大的特点,分析双层管对海床的传热机理中的对环境敏感因素,基于DNV-OS-F101规范要求,以初期的不稳定传热数据替代常规的稳态传热数据,对比理论计算与实测数据差异,用以判断海管是否发生渗漏,结果表明,油田的关停损失大幅减少,可供需要试压的在役双层海管管理参考。