海量遥感影像的存储与快速调度显示方法

随着计算机技术的发展,计算机的存储和处理的功能越来越强大,但是仍然无法满足日益增加的海量信息处理的需要。因此研究如何利用有限的计算机内存,处理无限大小的数据,成为研究的重点。本文根据海量遥感影像数据的特点以及对海量遥感图像进行处理的需要,研究了实现海量图像数据快速显示的方法以及其数据库存储结构。主要包括图像重采样、影像金字塔生成技术、图像快速显示技术等。     

Physical modelling of rainfall‐ and snowmelt‐induced erosion of stony slope underlain by permafrost

Physical modelling experiments have been carried out in a cold room to test on a small scale, the effects of water supply during the thaw of an experimental slope with permafrost. Permafrost was maintained at depth and a thin active layer was frozen and thawed from the surface. Data from the experiments relate to two different conditions, first with moderate rainfall, and second with heavy rainfall during the thaw period. When moderate rainfall is applied during thaw phases, the experimental slope is slightly degraded. At the scale of the experiment, erosion processes involve frost jacking of the coarse blocks, frost creep and gelifluction that induce slow and gradual down slope displacements of the active layer, but also small landslides leading to large but slow mass movements with short displacements. Changes in experimental slope morphology are marked by the initiation of a small‐scale drainage network and the development of a little crest line which shows a progressive upslope migration. With such boundary conditions, there is not enough water supply to evacuate downslope the whole of the eroded material and a topographic smoothing is observed. When heavy rainfall is applied during thaw periods, rapid mass wasting (small mud‐flows and debris flows) become prominent. Slope failures are largely controlled by the water saturation of the active layer and by the occurrence of steeper slopes. At the scale of the experiment, rates of erosion and maximum incision increase by about 100% leading to significant slope degradation with marked and specific scars comparable to gullying. These morphological changes are dependant on both the size and the frequency of catastrophic events. These experiments provide detailed data that could improve the knowledge of the physical parameters that control the initiation, at a small‐scale, of erosion processes on periglacial slopes with a thin active layer and/or with thin cover of mobilizable slope deposits. Copyright © 2010 John Wiley & Sons, Ltd.     

无损钻切技术在宝钢二号高炉快速大修改造工程中的应用

详细介绍了宝钢二号高炉快速大修改造工程中采用的无损钻切技术,即高精度水平钻孔、基础整体静力水平切割、注浆充填、抬升平移的施工方法及所用装置等。     

洪水浸泡和水位骤降情况下黄河下游堤防堤岸稳定性分析

水库库岸边坡稳定在水位骤降工况下的研究目前已比较成熟,但对黄河下游堤防在水位骤降工况下的堤坡稳定状态却研究甚少。通过选取黄河下游标准化堤防某段堤岸边坡为研究对象,建立有限元渗流模型,提出黄河下游堤防的水位骤降速度标准,同时分析了在水位骤降速度为2、4、5 m/d时的坡内浸润线变化、堤岸稳定性变化,以及在水位骤降组合洪水浸泡最不利工况下的堤岸稳定状态。通过分析,给出水位下降情况、水位下降组合浸泡情况下的堤岸稳定状态图,并从图中可以查出在某一水位下降速度、洪水水位降至某一高程处的堤岸稳定状态,为工程人员在堤防建设中运用和推广提供了便利。     

汶川地震触发的绵远河流域崩塌滑坡的特征

利用地震后ALOS影像自动提取了汶川地震重灾区绵远河流域内的崩塌滑坡,结合野外调查共确定地震触发崩塌滑坡1 073处,面积48.5 km2.其中分布最广、数量最多的是浅层崩滑体;同时由于地震力作用强烈,触发了许多深层、高速、远程滑坡,并形成了大量的滑坡堰塞湖.汶川地震诱发的第二大滑坡文家沟滑坡就位于流域内,该滑坡是本次地震中滑动距离最远的滑坡.地震导致大量的碎屑物质堆积在沟道内或悬挂在斜坡上,为泥石流的发生提供了有利条件.基于GIS的统计分析表明,地震滑坡的空间分布主要受发震断层的控制,流域内的崩塌滑坡受到了映秀-北川断裂和江油-都江堰断裂的双重影响,主要分布于两断裂上盘的一定范围内;地层岩性影响着地震滑坡的类型,岩浆岩、白云岩等硬岩主要发育浅层崩滑体,而上硬下软的地层多发生大型滑坡;大部分崩塌滑坡都发生在海拔1 000～2 000 m的高程内;坡度是崩塌滑坡发生的主要控制因素之一,大部分崩塌滑坡发生在25°～55°的范围内;坡向对滑坡的分布也有一定的影响,背靠震源(发震断层)方向的斜坡比面向震源(发震断层)方向更容易发生滑坡.     

2007号台风“海高斯”快速加强的成因分析

利用欧洲中期天气预报中心(European Center for Medium-Range Weather Forecasts,ECMWF)ERA-Interim逐6 h再分析数据(水平分辨率0.25°×0.25°)和国家气象中心提供的逐小时台风业务数据,分析了2020年第7号台风“海高斯”的路径和强度特征,并在此基础上分析其出现快速加强的原因。结果表明:1)“海高斯”个头小、海温异常偏高、风的垂直切变较小是其出现快速加强的有利因素;2)高空冷涡是“海高斯”后期高空北向出流打开的有利条件;3)来自副热带高压南侧的东向气流对“海高斯”水汽和涡度的输送也是其出现快速加强的有利条件。     

Mitigation of levee failures using deep mixed columns and geosynthetics

Stability of levees is critical to the safety of human and structures, especially at high water levels. Levees may fail due to the existence of soft soil foundations or seepage of water through the levees or rapid drawdown. Deep mixing technology has been considered one of the good alternatives to solve foundation and seepage problems while geosynthetics can be used to stabilize slopes during rapid drawdown. Studies have shown that deep mixed columns and geosynthetics can increase the stability of highway embankments over soft soils. In those studies, however, no ponding water exists on either side of the embankment, which is not the case for levees. Experimental studies have shown that deep mixed columns under a combination of vertical and horizontal force could fail due to shear or tension/bending or rotation. A finite difference method, incorporated in the FLAC (Fast Lagrangian Analysis of Continua) Slope software, and a limit equilibrium method (specifically Bishop's method), incorporated in the ReSSA software, were adopted in this study to investigate the stability of the levee with ponding water or under rapid drawdown. In this study, deep mixed columns were installed in continuous wall patterns, which were modeled as 2D deep mixed walls. Geosynthetic layers were modeled using cable elements with grout properties between geosynthetic and soil in the numerical analysis. Mohr-Coulomb failure criteria were used for the levee, the soft soil, and the deep mixed walls. The stability of a levee at different stages (end of construction, average service condition, high water surge, and rapid drawdown from the service condition and the highest water level condition) was examined. The study clearly demonstrated that the deep mixed walls can enhance the stability of the levee by providing shear/moment resistance and hindering seepage through the levee and geosynthetics can enhance the riverside slope stability of the levee by providing tensile resistance to the soil.     

西北区域自动地震速报系统定位结果评估

西北区域自动地震速报系统是中国地震局5大区域速报系统之一.分析了2009年7月1日至2011年8月31日该系统产出的149个天然地震与全国统一地震编目系统定位结果的匹配情况:97.3％的地震发震时刻偏差小于5 s;96％的地震震中偏差分布在5～30 km之间;94％的地震深度偏差不超过5 km;68.5％的地震震级偏差不大于0.3.分析了7个非天然地震的匹配情况.并对未匹配地震及偏差较大地震作了进一步的分析.对自动地震速报系统的整合与完善提出了一些建议.     

Direct displacement‐based seismic assessment procedure for multi‐span reinforced concrete bridges with single‐column piers

In Italy, as in other high seismic risk countries, many bridges, nowadays deemed ‘strategic’ for civil protection interventions after an earthquake, were built without antiseismic criteria, and therefore their seismic assessment is mandatory. Accordingly, the development of a seismic assessment procedure that gives reliable results and, at the same time, is sufficiently simple to be applied on a large population of bridges in a short time is very useful. In this paper, a displacement‐based procedure for the assessment of multi‐span RC bridges, satisfying these requirements and called direct displacement‐based assessment (DDBA), is proposed. Based on the direct displacement‐based design previously developed by Priestley et al., DDBA idealizes the multi DOF bridge structure as an equivalent SDOF system and hence defines a safety factor in terms of displacement. DDBA was applied to hypothetical bridge configurations. The same structures were analyzed also using standard force‐based approach. The reliability of the two methods was checked performing IDA with response spectrum compatible accelerograms. Copyright © 2012 John Wiley & Sons, Ltd.     

山东省地震烈度速报系统研制与应用

发展地震烈度速报系统是我国现阶段防震减灾事业的一项重要工作.其目的是在地震发生后,对强震动数据进行实时分析和处理,快速给出强震对地表的破坏程度——地震烈度分布图.鉴于目前国内强震动台网分布密度及数据传输方式等诸多因素的限制,多数烈度速报系统是基于美国的ShakeMap系统进行二次开发生成烈度分布图,其计算过程更多地依赖于对地震破裂过程的反演及地震烈度衰减关系,产出的烈度图是静态位图,分辨率较低,与丰富的地理信息难以无缝衔接(Wald et al,1999a;张晁军等,2010;泽仁志玛等,2006).