Moisture content of natural stone: static and dynamic equilibrium with atmospheric humidity     

C. Franzen  P. W. Mirwald 《Environmental Geology》2004,46(3-4):391-401

Among hygric properties of stone material, the sorption behaviour is of essential importance because of the permanence of the processes involved. New results from static sorption experiments performed by standard techniques and by a new tool are reported for six different building stones. Furthermore, an example of dynamic sorption behaviour under continuously changing humidity is presented. For the static equilibrium sorption measurements a close relation to the stone type, its pore properties, such as specific inner surface, pore volume, pore size distribution as well as capillary water uptake and water saturation, is drawn. The comparison of the different data allows us to retrieve correlations between material features that are crucial for weathering processes. The sorption–desorption processes respond spontaneously on even small humidity changes as shown by the dynamic sorption experiment. A permanent breathing-process of the material is imposed.  相似文献   

Analysis of coastal damage of a beach profile under the protection of emergent vegetation   总被引：1，自引：0，他引：1  

U. Türker  O. Yagci  M.S. Kabdal&#x; 《Ocean Engineering》2006,33(5-6):810-828

The primary objective of the study was to experimentally explore the protection performance of the emergent vegetation on the morphological changes of a coastal zone. The experiments were conducted under both regular and irregular waves in two different wave flumes. A dimensionless number was derived to characterize the beach profile response under the protection of emergent vegetation. Accordingly, empirical relations were derived that explained the pattern exhibited by the experimental data. The list of wave parameters and beach erosion related functions were incorporated in relation to vegetation intensity in order to define coastal zone response. The relationships of these functions followed good trends with the derived dimensionless number. The findings showed that fall speed parameter is not necessarily involved whereas depth parameter is an important factor while defining the damage. The damage parameter is also considered to formulate the limits of dynamic and static stability of beach profiles under the protection of emergent vegetation.  相似文献   

Static stability of submerged partial revetment structures under regular and irregular waves     

K. Günayd&#x;n  M. S. Kabda l&#x; 《Ocean Engineering》2003,30(6):761-777

Physical models of submerged partial revetment structures were built on natural beach sand with a diameter of 0.35 mm and specific gravity of 2.63. The armor units, the diameter and specific gravity of which varied in the range of 8.5–67.95 mm and 1.81–2.77 respectively, were placed only on wave breaking areas. A series of experiments has been conducted on the conditions of different armor units and different wave characteristics using regular waves and irregular waves. Based on the experimental data, the effects of wave height, wave period, diameter and specific gravity of armor units, water depth in the channel, and wave types on static damage of given structures are assessed. Some empirical formulas have been suggested through regression analysis to describe static stability and stability number of submerged partial revetment structures under pure regular waves, pure irregular waves, and regular–irregular waves. The suggested formulas compared with Van der Meer’s (1988) formulas and some differences have occurred because of differences among revetment types and test conditions; therefore, proposed formulas give reasonable results for the test conditions used.  相似文献   

多波束测深系统的精度评估方法研究   总被引：2，自引：1，他引：2  

吴英姿  徐新盛  乔力争 《海洋技术学报》2003,22(3):65-69

在分析了多波束测深系统测量误差来源的基础上，讨论了多波柬测深系统静态精度、相对精度和绝对精度的系统精度评估方法。采用的静态精度评估方法就是在多波柬测深系统静止的条件下考核其对同一位置测量深度的误差；相对精度评估方法就是布设多条交叉重叠的测线，考核交叉重叠点的测深误差；绝对精度评估方法是在多波束测深的同时利用高精度的测深仪测量同一区域，用此参考地理模型来检验多波束测深的精度。根据误差理论，三种精度评估的方法分别从系统稳定性、自符合性和系统误差方面确定各误差源的综合误差，它们是检验多波束测深系统精度是否符合海道测量标准的有效方法。文中给出了系统试验数据的重要结果及设备验收的方法。  相似文献   

Analysis of stiffened shell for ships and ocean structures by finite element method     

B. Gangadhara Prusty  S. K. Satsangi   《Ocean Engineering》2001,28(6)

Static analysis of stiffened shells has been carried out using an eight-noded isoparametric element for the shell and a three-noded curved beam element for the stiffener. A same displacement function is used for the shell and the stiffener elements. A modified technique has been followed to analyse the shell, which is an improvement over the degenerated shell concept. The stiffness matrix of the curved beam element is generated irrespective of its position and orientation within the shell element. The stiffness matrix of the stiffener is then transferred to all the nodes of the shell element. Numerical examples of stiffened shells with concentric and eccentric stiffeners have been analysed and the results presented together with those available in published literature.  相似文献   

YE地区低信噪比复杂地表资料的静校正处理技术          下载免费PDF全文

肖盈  居兴国  齐玉涛  刘燕峰  邹少峰 《山东国土资源》2017,33(11)

当地震资料既存在严重静校正问题,信噪比又极低时,严重的静校正问题会制约提高信噪比技术的效果,同时低信噪比问题又会严重导致静校正问题得不到很好解决,两者形成一种耦合关系,严重影响资料的成像效果。以解决复杂地表条件下低信噪比资料的静校正问题为出发点,讨论了折射层析静校正和初至波层析静校正适用性,提出了层析静校正融合技术;分析了生产中常用模型迭代剩余静校正和非地表一致性剩余静校正方法的适用性,提出了基于蒙特卡罗剩余静校正与模型约束最大能量剩余静校正的综合剩余静校正技术,摸索出一套有效解决低信噪比资料静校正问题的处理技术。以YE地区存在严重静校正问题的低信噪比资料为例,验证了所述静校正处理技术的有效性。  相似文献   

应力触发模型研究进展概述     

姜辉  王琼  王海涛 《内陆地震》2008,22(3):271-281

对应力触发问题的研究从20世纪60年代至今已近半个世纪。这半个世纪以来,地震专家和学者通过对大量震例的分析和比较,在应力触发问题某些方面的研究逐渐从探索性趋向系统性。主要从静态库仑破裂应力、动态库仑破裂应力和完整库仑破裂应力3方面简要概述其对地震触发的作用。  相似文献   

土体触探静力加载试验的FLAC模拟模型选择   总被引：1，自引：1，他引：0  

谢守益  徐卫亚  Roland GOURVES 《工程地质学报》1999,7(2):187-192

本文将触探静力加载试验作为轴对称问题处理,建立了两种不同FLAC轴对称模型,等荷载模型和等位移模型。研究表明,两种模型的FLAC模拟结果基本一致,一般条件下,应用简化的、运算速度快的等荷载模型可以满足试验要求。  相似文献   

流-固耦合作用对计算同震静态库仑应力变化的影响          下载免费PDF全文

缪淼  朱守彪 《地球物理学报》2017,60(4):1457-1469

传统方法计算同震静态库仑应力变化一般都是基于Okada的解析解,模型中不考虑流体对固体骨架力学行为的影响.但实际上,流体对固体变形有着非常重要的作用.为此,本文基于孔隙弹性理论,考虑流-固之间的完全耦合效应,针对三种典型的断层错动模型(走滑型、逆冲型以及正断型),分别计算静态库仑应力变化与传统算法之间的差别.计算结果表明:三种地震模型得到的介质孔隙压变化在空间的分布格局完全不同,走滑型地震产生的孔隙压变化图案在空间中呈正负相间的四象限分布,近场的静态库仑应力明显下降,流-固耦合作用对静态库仑应力变化影响较大.逆冲型和正断层型地震产生的介质孔隙压变化在空间的分布图案类似,但正负区域正好相反,孔隙压在逆冲型地震的震源区域上升,而在正断型地震的震源区域下降.同传统方法计算的库仑应力相比,逆冲型地震产生的介质孔隙压变化使得震源区的应力影区面积减小,这会触发更多的余震;而正断型地震产生的孔隙压变化则正好相反,增大了震源附近的应力影区范围,这样会降低该区域余震发生的概率.可见,介质的流-固耦合作用对计算库仑应力变化的影响不可忽视.因此,在利用库仑应力变化研究地震触发时,应考虑流-固耦合作用,使得库仑模型的预测结果更符合实际.  相似文献   

九寨沟7.0级地震地表地震动位移及静态位移的模拟研究          下载免费PDF全文

周红 《地球物理学报》2018,61(12):4851-4861

北京时间2017年8月8日21时19分在四川省阿坝州九寨沟县（北纬33.2°、东经103.8°）发生7.0级地震,给九寨沟景区造成了滑坡坍塌等地质灾害.本文利用Crust1.0资料和反演的震源破裂过程建立了研究区三维介质模型及三维震源模型,采用谱元数值模拟方法模拟了九寨沟近断层地表地震动速度时程,并与强震台站实际速度记录的低频做了对比,两种结果对比的一致性,验证了介质模型及震源模型的有效性.在此基础上近一步模拟了地表位移时间序列,获得了位移峰值PGD及静态位移的空间分布,分析并给出了九寨沟地震地表位移的主要运动特征.  相似文献