Stochastic response surface method for reliability analysis of rock slopes involving correlated non-normal variables

This paper proposes a stochastic response surface method for reliability analysis involving correlated non-normal random variables, in which the Nataf transformation is adopted to effectively transform the correlated non-normal variables into independent standard normal variables. Transformations of random variables that are often used in reliability analyses in terms of standard normal variables are summarized. The closed-form expressions for fourth to sixth order Hermite polynomial chaos expansions involving any number of random variables are formulated. The proposed method will substantially extend the application of stochastic response surface method for reliability problems. An example of reliability analysis of rock slope stability with plane failure is presented to demonstrate the validity and capability of the proposed stochastic response surface method. The results indicate that the proposed stochastic response surface method can evaluate the reliability of rock slope stability involving correlated non-normal variables accurately and efficiently. Its accuracy is shown to be higher than that for the first-order reliability method, and it is much more efficient than direct Monte-Carlo simulation. The results also show that the number of collocation points selected should ensure that the Hermite polynomial matrix has a full rank so that different order SRSMs can produce a robust estimation of probability of failure for a specified performance function. Generally, the accuracy of SRSM increases as the order of SRSM increases.     

A two dimensional hydrodynamic and sediment transport model for dam break based on finite volume method with quadtree grid

This study aims to develop a robust, accurate and computationally efficient hydrodynamic and sediment transport model for dam break flows. The two dimensional shallow water equations are resolved based on the finite volume method with an unstructured quadtree mesh. The sediment transport and bed evolution modules are coupled with hydrodynamic module to predict simultaneously the hydrodynamics, sediment concentrations and morphological changes. The interface flux is computed by the HLL approximate Riemann solver with second order accuracy. The effects of pressure and gravity are included in source term in this model, which can simplify the computation and eliminate numerical imbalance between source and flux terms. For dam break flows occurring in complicated geometries, the quadtree rectangular mesh is used to refine the interesting area and important part. The model is first verified against results from laboratory experiments, existing numerical models and real life case. It is then used to simulate dam break flows over a mobile bed to investigate the bed evolution. The results are compared with experimental data and field data with good agreement. The method is simple, efficient, and conservative. It shows promise for handling hydrodynamic simulation and sediment transport for a wide range of dam break flows.     

Tidally averaged circulation in Puget Sound sub-basins: Comparison of historical data,analytical model,and numerical model

Through extensive field data collection and analysis efforts conducted since the 1950s, researchers have established an understanding of the characteristic features of circulation in Puget Sound. The pattern ranges from the classic fjordal behavior in some basins, with shallow brackish outflow and compensating inflow immediately below, to the typical two-layer flow observed in many partially mixed estuaries with saline inflow at depth. An attempt at reproducing this behavior by fitting an analytical formulation to past data is presented, followed by the application of a three-dimensional circulation and transport numerical model. The analytical treatment helped identify key physical processes and parameters, but quickly reconfirmed that response is complex and would require site-specific parameterization to include effects of sills and interconnected basins. The numerical model of Puget Sound, developed using unstructured-grid finite volume method, allowed resolution of the sub-basin geometric features, including presence of major islands, and site-specific strong advective vertical mixing created by bathymetry and multiple sills. The model was calibrated using available recent short-term oceanographic time series data sets from different parts of the Puget Sound basin. The results are compared against 1) recent velocity and salinity data collected in Puget Sound from 2006 and 2) a composite data set from previously analyzed historical records, mostly from the 1970s. The results highlight the ability of the model to reproduce velocity and salinity profile characteristics, their variations among Puget Sound sub-basins, and tidally averaged circulation. Sensitivity of residual circulation to variations in freshwater inflow and resulting salinity gradient in fjordal sub-basins of Puget Sound is examined.     

中国地质调查信息网格平台构建和地质图 数据服务的实现

对组成中国地质调查信息网格平台的结点计算池的构架、机制和组成结点计算池的资源聚合器、元服务、智能服务引擎的概念进行了阐述,提出了结点自治的方案;基于资源共享、虚拟化、Web服务等创建了基于元数据服务、栅格流服务、矢量地图服务、三维可视化服务等多模式的地质图数据服务。目前已初步构建了中国地质调查信息网格,连通10个结点 ,为地质图空间信息共享和应用提供一种全新的技术解决方案,取得了良好的实际运行效果。     

方格网布孔法注浆设计在底板改造中的应用

为了安全回采受底板承压水害威胁的采煤工作面,可采取注浆改造的防治水方法,而注浆改造设计是注浆改造的基础和前提。由于传统设计方法较为繁琐且效率较低,本次研究,首先对方格网布孔法的设计原理与基本思路进行了介绍,然后以新桥煤矿北二采区2207工作面为例,对根据工作面大小和底板水文地质情况设计方格网,输入基本参数,得出需要施工的钻孔参数,并根据物探资料及实际揭露的底板灰岩岩溶裂隙发育情况的变化,及时调整钻孔数量与位置进行了详细说明。应用效果表明,该方法具有设计简便,钻孔布置均匀,重点突出,清除了设计盲区,底板注浆改造效果好的特点,是一种操作简便、安全高效的注浆设计方法。     

基于CUBE算法的多波束测深数据自动处理研究

对CUBE算法自动处理多波束测深数据的模型建立、格网节点的多重估计和最优估值选取准则进行了详细介绍,深入分析了多重估计的实用性,并通过实测数据对该算法进行实现.利用了抗差Kalman滤波改进CUBE算法.通过模拟数据对改进的CUBE算法进行实验,验证了算法改进的必要性.     

基于最小二乘配置模型探讨青藏高原巴彦喀拉块体的运动特征

论述了块体刚性运动和最小二乘配置模型的原理及构建方法,并对青藏高原中部巴彦喀拉块体的运动趋势及内部形变进行了深入研究.基于最小二乘配置模型,通过建立推估点与观测点间的协方差矩阵,能够较好地区分块体整体刚性旋转及内部的弹性形变,削弱了点位分布对形变场构建产生的影响,从而准确描述区域地壳运动的趋势及应变场特征.结果表明:巴...     

球面格网系统特征分析及比较

球面格网系统是一种新型栅格数据模型。在全面检索和分析前人相关研究成果的基础上,将球面格网系统分成4种类型:基于经纬线划分的格网系统、基于正多面体划分的格网系统、基于Voronoi划分的格网系统和混合格网系统;并针对各种不同类型的格网,分析了同级格网单元的空间几何特征及不同级别格网之间的层次嵌套等特性。通过对比分析,给出不同格网系统的优缺点及其适用领域,认为不存在满足所有需求的通用的格网系统,相关应用只能针对具体情况,选用最适宜的格网系统。     

The impact of heterogeneity of land surface roughness length on estimation of turbulent flux in model

Based on preliminary theoretical analysis and numerical experiment, it is found that land surface heterogeneity plays an important role in the models turbulent flux calculation. In nearly neutral atmosphere conditions, variation coefficient of sub-scale roughness length, cell-average roughness, and reference height are main factors affecting the calculation of grid turbulent fluxes. The first factor has a determinant role on calculation deviation. The relative error generated by roughness heterogeneity could be more than 40% in some cases in certain areas (e.g., in vegetation-climate transition belt). Selecting a specific reference height may improve the calculation of turbulent flux. In stable or unstable atmosphere conditions, with sensible heat flux as an example, analysis shows that the discrepancy is correlated to the sub-grid distributions of mean wind velocity, potential temperature gradient between land surface and reference levels, and atmosphere stability near surface layer caused by the heterogeneity of land surface roughness. The calculation of turbulent flux is the most sensitive to stability in the above three factors. The above analysis shows that it is necessary to make a further consideration for the calculation deviation of the turbulent fluxes brought from land surface heterogeneity in the present numerical models.     

制造网格中资源的区间转化与多目标优化选择方法

针对制造网格资源检索问题,提出了用区间方法描述制造资源与制造任务能力参数的思想,同时给出了能力参数从区间形式转化为确定值形式的具体转化规则.结合多目标优化思想,构造了基于距离的目标函数和遗传算子.采用基于非支配解的快速排序方法产生一组非支配解供用户选择.最后给出一个典型事例,验证该算法的有效性.