基于PLAXIS和OPTUM的路堤加筋数值模拟

为讨论PLAXIS和OPTUM在加筋路堤模拟技术上的差异,并探究路堤填筑过程中关键力学响应的动态演变规律,提出2款程序中界面参数的等效转换方式,并基于2款程序分别建立了加筋路堤数值分析模型。结果表明,2款程序的Geogrid单元类型及节点数不同,PLAXIS拥有更丰富的筋材本构模型,而OPTUM在考虑拉伸截断时则更为全面;PLAXIS所获轴向拉力略小于OPTUM,2款程序计算所获界面剪切应力差值在最大剪应力附近位置相较其他位置更大,OPTUM中危险滑动面更靠深处;随路堤填筑,筋材轴向拉力整体作用逐渐发挥,而筋土界面抗剪作用则主要发挥在靠近坡脚一侧。

含水率变化对黄河下游滩岸土体力学性质影响及稳定性分析

黄河下游滩区岸坡坍塌,压缩滩区人民的生产空间,造成了极大的经济损失。因此,在对万滩镇至柳园口段滩岸踏勘、取样以及室内土工试验的基础上,分析滩岸土体组成及结构特征,研究含水率变化对土体强度的影响,并利用Optum G2研究土体强度变化对多层土滩岸稳定性的影响。结果表明:黄河万滩镇至柳园口段滩岸土体由黏土和粉砂土组成,表现为交互分层结构;随着含水率的提高黏土和粉砂土黏聚力均先增大后减小,内摩擦角逐渐减小;含水率对岸坡土体强度产生显著影响,含水率从18%增大到40%时黏土层黏聚力降低80%、内摩擦角降低约87%;滩岸组合边坡稳定性降低,岸坡稳定系数随着含水率提高表现为先增大后减小。

Use of the Cam-Clay Model in Finite Element Calculations after Identification of Soils from Simple Mechanical Tests

In order to make the use of complex elasto-plastic behavior models more accessible, we attempted to identify the Cam-Clay model in two samples of tropical and lateritic soils (from Senegal/West Africa) from casagrande box shear and oedometric tests. This methodology was used as a substitute for triaxial trials. In this article, we first verify the test results by the finite element method with the Optum software. We use a simulation of the tests with the modified Cam Clay model as the behavior model. Then, we simulate the oedometric test on tropical soils with the Castem software and also use the modified Cam Clay model. These calculations make it possible to write the criterion of plasticity of the material starting from the expression of the surface of load while passing by the calculation of the volumetric and deviatoric stresses.

注射用头孢呋辛钠原粉结晶工艺优化

针对国内由头孢呋辛钠无菌原料药经无菌分装得到的头孢呋辛钠粉针剂存在质量及稳定性差的情况,对头孢呋辛钠原料药结晶工艺进行了优化。通过对比碳酸氢钠、异辛酸钠等不同成钠剂,优化结晶温度、结晶pH值、搅拌强度和结晶体系等工艺参数,得到了与原研产品一致的晶型,从而提高了注射用头孢呋辛钠的质量和稳定性。