半空间埋置动点源荷载问题的传递矩阵法

引用了流体饱和两相多孔介质的动力控制方程分析半空间埋置动点源荷载问题的位移和变形。经过Laplace Hankel变换 ,控制方程化成常微分方程组。利用数学软件mathmatic对上述方程组求解 ,可以得到单层砂土的传递矩阵。分析过程中 ,假设在两层面上 ,位移与应力相互连续 ,可以借鉴有限元的思想进行耦合计算。这样就获得了在饱和砂土中施加竖向动荷载问题的Laplace Hankel变换解 ,其最终的解还需要通过Laplace Hankel逆变换得到     

A new method for testing pile by sin- gle-impact energy and P-S curve

Introduction Through many year's practices by vast numbers of scientific and technological workers andefforts from all aspects, the dynamic testing method of high-low strain has formally entered intothe technical code of foundation pile test of construction at last (The Industry Standards of thePeople's Republic of China, 2003). The striking mode of the dynamic testing method of high strainis stipulated as hammer in the code, the striking of rocket can also be used. The latter is widely…     

运用改进系统建模法对南海气象数据的建模研究

在系统建模理论的基础上,运用改进的动态数据建模方法,对南海气象数据中的温度进行建模并验证了模型的适用性.根据模型推导出格林函数、逆函数和自协方差函数等,并讨论了南海气象数据中温度模型的稳定性、可逆性和合理性.对系统的频率特性和谱函数进行分析讨论,并给出建模过程中的一些图像.根据模型的适用性检验发现,对所研究的气象数据而言,ARMA(4, 3)模型是最合适的,具有平稳可逆性.所有的建模和分析过程在MATLAB上实现.实验结果表明这种建模方案简便易行,能够快速准确地确定系统的合理模型.     

SH波对无限介质土中衬砌结构的动应力集中

运用复变函数法和保角映射法对无限介质土中的衬砌结构进行分析.通过引入两个势函数将弹性介质的控制方程解耦成两个Helmholtz方程.利用所得势函数的通解,得到无限土介质和衬砌结构的位移和应力的表达式,利用无限介质与衬砌结构之间的连续性条件和衬砌结构内边界上的边界条件,可确定波函数展开式中的末知系数,并给出动应力集中系数的数值结果.     

龙首二级面板堆石坝三维真非线性地震反应分析和评价

基于土石料三维粘弹塑性动力本构模型,并采用新型三维各向异性有厚度薄单元来模拟面板和堆石的接触面特性,建立了高面板堆石坝地震反应分析的三维真非线性动力分析方法.利用坝料动力特性的大型三轴试验成果,分析计算了龙首二级(西流水)面板堆石坝的地震反应,主要包括加速度反应、堆石体应力反应及坝体单元抗震安全系数、面板应力反应和变形及接缝位移、高趾墙动力反应等.为大坝的抗震设计提供了有力的技术依据.     

水位下降卸荷诱发库岸边坡快速失稳机理分析

本文以某工程现场岩质边坡为例，采用与传统裂隙水压力分布不同的水压力分布方式和边坡裂隙中可能发生的水锤效应相耦合，分析研究了岩质边坡发生滑动的机理及稳定性。研究表明，本文所采用的水压力分布方式较为符合边坡中的水压力分布实际情况，可以给出一个较为合理的稳定系数。当考虑水锤效应时，岩质边坡的稳定系数大大降低，说明水锤效应加剧了边坡破坏失稳的过程。本文所采用的水压力分布方式与边坡裂隙中的水锤效应相耦合的计算方法，在边坡稳定性分析中具有参考意义。     

天津泰达地区粉土振动液化特性的研究

本文以动三轴试验和原位测试数据为基础，以天津地区砂性土为例，探讨砂性土振动液化机理及孔隙水压力变化规律，采用多种方法分析判别砂性土液化，为高烈度地区重要工程建筑抗震设计提供重要数据。     

金丽温高速公路K81高边坡变形动态数值分析

对金丽温高速公路K81高边坡进行接触大变形有限元动态数值分析.结果表明,路堑边坡开挖,导致滑面的法向应力减小、抗滑力下降,是引起古滑坡复活的根本原因.研究结果也说明了接触大变形有限元分析方法可以较好地分析潜在滑面的力学作用,是研究滑坡的滑动机理的有效方法.     

Application of Remote Sensing in Flood Management with Special Reference to Monsoon Asia: A Review

The conventional means to record hydrological parameters of aflood often fail to record an extreme event. Remote sensingtechnology along with geographic information system (GIS)has become the key tool for flood monitoring in recent years.Development in this field has evolved from optical to radarremote sensing, which has provided all weather capabilitycompared to the optical sensors for the purpose of flood mapping.The central focus in this field revolves around delineation of floodzones and preparation of flood hazard maps for the vulnerable areas.In this exercise flood depth is considered crucial for flood hazardmapping and a digital elevation model (DEM) is considered to bethe most effective means to estimate flood depth from remotelysensed or hydrological data. In a flat terrain accuracy of floodestimation depends primarily on the resolution of the DEM. Riverflooding in the developing countries of monsoon Asia is very acutebecause of their heavy dependence on agriculture but any floodestimation or hazard mapping attempt in this region is handicappedby poor availability of high resolution DEMs. This paper presents areview of application of remote sensing and GIS in flood managementwith particular focus on the developing countries of Asia.     

Three-dimensional forward and backward modelling of diapirism: numerical approach and its applicability to the evolution of salt structures in the Pricaspian basin

Numerical studies of ductile deformations induced by salt movements have, until now, been restricted to two-dimensional (2D) modelling of diapirism. This paper suggests a numerical approach to model the evolution of three-dimensional (3D) salt structures toward increasing maturity. This approach is also used here to restore the evolution of salt structures through successive earlier stages. The numerical methodology is applied to study several model examples. We analyse a model of salt diapirs that develop from an initial random perturbation of the interface between salt and its overburden and restore the evolved salt diapirs to their initial stages. We show that the average restoration errors are less than 1%. An evolutionary model of a 2D salt wall loaded by a 2D pile of sediments predicts a decomposition of the salt wall into 3D diapiric structures when the overburden of salt is supplied by 3D synkinematic wedge of sediments. We model salt extrusion feeding a gravity current over the depositional surface and estimate an average rate of extrusion and horizontal velocity of salt spreading. Faulting of the overburden to salt overhangs initiates new secondary diapirs, and we analyse the growth of these secondary diapirs. We also study how lateral flow effects the evolution of salt diapirs. The shape of a salt diapir can be very different if the rate of horizontal flow is much greater than the initial rate of diapiric growth solely due to gravity. We discuss the applicability of the results of the models to the evolution of Late Permian salt structures in the Pricaspian basin (Russia and Kazakhstan). These structures are distinguishable into a variety of styles representing different stages of growth: salt pillows, diapirs, giant salt massifs, 2D diapiric walls and 3D stocks complicated by large overhangs. The different sizes, shapes and maturities of salt structures in different parts of the Pricaspian basin reflect areal differences in salt thickness and loading history. Our results suggest that the numerical methodology can be employed to analyse the evolution of all salt structures that have upbuilt through younger ductile overburdens.