Effect of tunnel advance rate on seepage forces acting on the underwater tunnel face

In this paper, the effect of seepage forces arising from the groundwater flow on the tunnel face stability was studied for underwater tunnels. The groundwater flow equation was solved and the seepage forces acting on the tunnel face were calculated using the upper bound solution in limit analysis. Especially, the effect of tunnel advance rate on the seepage forces and thus on the tunnel face stability was studied. A finite element program to analyze the groundwater flow around a tunnel with the consideration of tunnel advance rate was made. Example problem showed that the seepage force is greatly influenced by the tunnel advance rate in case of less permeable ground. Finally, a rational design methodology for the assessment of support pressures required for maintaining the stability of the tunnel face was suggested for underwater tunnels.     

广州民航芙蓉山庄规划设计

通过广州民航芙蓉山庄的规划设计与建筑创作，探索了中国山水文化的传承和山水居住建筑在新形势下的发展道路，并关注了房地产开发如何与环境保护相协调等问题。     

弹性地基上十字交叉梁考虑上部结构影响分析的超元法

本文提出弹性地基上十字交叉梁考虑上部结构影响分析的超元法 ,即将房屋上部每榀框架各层梁与基础梁在X方向和Y方向均简化处理成一根等效梁 ,整个结构视为弹性地基上十字交叉梁系 ,导出等效梁的超级单元刚度矩阵 ,然后用有限元法分析。本方法计算简便 ,适应性强 ,且具有较高的精度。     

An efficient methodology for robustness evaluation by advanced interval analysis using updated second-order Taylor series expansion

An enhanced and efficient methodology for interval analysis is proposed to evaluate the robustness of an uncertain structure. While a basic assumption of “inclusion monotonic” is introduced in some of the interval analyses, the possibility is taken into account of occurrence of the extreme value of the objective function in an inner domain of interval parameters. It is shown that the critical combination of interval parameters can be derived explicitly so as to maximize the objective function by second-order Taylor series expansion. Two different approaches, called the FRP (Fixed Reference-Point) method and the URP (Updated Reference-Point) method, are proposed to obtain such a critical combination of interval parameters. The method is applied to building structures with passive dampers sustained by flexible supports. The objective function is given by the sum of the mean squares of interstorey drifts under random input. The damper capacity, its supporting member stiffness and building storey stiffness are taken as interval parameters. In order to investigate the validity of the proposed methods, numerical analyses are conducted for 2- and 20-storey building models including passive dampers. By comparing the results with the reference solution and those by other conventional methods, it is demonstrated that the URP method can provide the most accurate response bounds without hard computational effort.     

基于下限有限元法的条形浅基础极限承载力分析

以极限分析下限法理论为基础,利用应力型有限元法建立满足条件的静力许可应力场,将地基的极限承载力问题归结为一个非线性数学规划问题。依据几何上的相似性,引入二阶锥形规划方法,采用预示校正内点法,避免屈服准则(Mohr-Coulomb)顶点约束的线性化近似,实现下限法数学模型的求解。并以均质土体的刚性条形基础的极限荷载为算例,比较了所得数值解与理论解,论证了该法的正确性和有效性。     

上限有限元定理在挡土墙土压力问题中的应用

在上限定理的基础上,将墙后土体离散为三角形单元,在单元中构造线性速度场,根据相关联流动法则以及边界条件建立约束方程,引入数学规划方法寻求挡土墙土压力为三角形分布时的土压力系数的上限解。通过具体的算例说明该方法是一种有效的数值方法。     

Lower bound buckling strength of axially loaded sandwich cylindrical shell under lateral pressure

Effects of the lateral pressure on the FEM and reduced stiffness lower bound buckling strength of axially loaded sandwich cylindrical shell are examined. Further, a reduced stiffness lower bound buckling strength for the axially loaded sandwich cylindrical shell under lateral pressure is proposed. The effect of the lateral pressure on the FEM and reduced stiffness lower bounds are corresponding; it causes them to reduce slightly. However, reduced stiffness buckling mode shape remains the same. In addition, the proposed reduced stiffness lower bound buckling strength is shown to provide effective and valid for cores having different shear stiffness. It provides comparatively close lower bounds to short axially loaded sandwich cylindrical shells under lateral pressure. Further, it provides a safe lower bound that does not depend on precise geometrical imperfection spectra and lateral pressure and it is simple and easy to employ.     

我国建筑地面工程技术的新进展：新版《建筑施工手册》第26章内容精选

新版《建筑施工手册》中充实了有防水要求楼面，地面变形缝的设置与和法，水泥类面层质量通病防范措施等内容，增列了新的地面类型反映了我国近１０年来地面与楼面施工技术的新发展。     

应用极点对称模态分解分析径流时空演化规律

研究径流演化规律对水文预报和水资源合理配置具有重要意义。鉴于径流序列具有多时间尺度与非线性趋势混叠的特征,利用自适应、无基的极点对称模态分解（ESMD）将长江上游干支流8站的年、月、日径流序列分解为各模态分量和趋势余项,甄别大尺度循环和非线性趋势;利用周期图、趋势余项、时频分析,同时掌握径流周期、趋势、突变规律,并与现有方法对比分析。结果表明：时间上,主要存在2年、6年、10 ~ 11年的年际与6个月、1年、2年、4年、22 ~ 23年的年内周期规律。空间上,除朱沱站年内、年际径流呈增加趋势,其余站径流均呈减少趋势;8站的突变规律也不完全相同。ESMD能同时从周期、趋势、突变来挖掘径流水文特性,为径流时空演化规律分析开辟新思路。     

高速公路沥青混凝土路面结构设计与质量控制

从原材料的选择、配合比的调整、设计与验证介绍了沥青混凝土上面层的配合比设计，并对其关键施工技术作了论述，最终保证高速公路沥青混凝土路面的工程质量。