"地震数值模拟的数据库应用平台"项目成果介绍

利用计算机模拟复杂的系统和过程,是当今世界科技发展的新潮流,在地学领域,数值模拟已经渗透到地学研究的各个重大领域。本项目提出建立一个用于地震模拟和预报的数据库应用平台,以地壳动力学研究和强震机理研究为应用核心,将地震地质研究、地形变研究、地应力研究、地球内部结构研究等多种相关的学科手段的观测资料、实验结果和理论分析有机地结合起来,实现技术和数据资源的共享。利用这些信息构建比较合理的地球模型和尽可能多的约束条件,并在有限元分析系统上进行地壳形变和地震过程的数值模拟。     

Correlation study between ground motion intensity measure parameters and deformation demands for bilinear SDOF systems

The correlation between ground motion intensity measures （IM） and single-degree-of-freedom （SDOF） deformation demands is described in this study. Peak ground acceleration （APG）, peak ground velocity （VPG）, peak ground displacement （DPG）, spectral acceleration at the first-mode period of vibration [As（T1）] and ratio of VPG to APG are used as IM parameters, and the correlation is characterized by correlation coefficients p. The numerical results obtained by nonlinear dynamic analyses have shown good correlation between As（T1） or VPG and deformation demands. Furthermore, the effect of As（T1） and VPG as IM on the dispersion of the mean value of deformation demands is also investigated for SDOF systems with three different periods T=0.3 s, 1.0 s, 3.0 s respectively.     

井间断层的计算机分析方法

井间断层分析的研究,是油气储层地质研究的一项重要基础性工作,对油气的运移和聚集其中重要的控制作用。它是利用测井资料,以地层分层为基础,采用计算机技术实现井间断层分析的一种井间断层自动分析方法。动态波形匹配算法是本次研究采用的主要算法,它能够很好地建立井间地层之间的对比关系,通过曲线拟合、特征提取、匹配代价计算等步骤,自动绘制井间地层对比的路径图解。本文在对各种构造的路径图分析的基础上,总结出正断层、逆断层、不整合、同沉积断层、犁式断层和地层尖灭等30种情况下的路径图模式,提出路径图模式及相关概念。在大港油田的实例分析中取得了很好的效果。     

Modelling methods of historic masonry buildings under seismic excitation

Historic masonry buildings in seismically active regions are severely damaged by earthquakes, since they certainly have not been explicitly designed by the original builders to withstand seismic effects, at least not in a ‘scientific’ way from today’s point of view. The assessment of their seismic safety is an important first step in planning the appropriate interventions for improving their pertinent resistance. This paper presents a procedure for assessing the seismic safety of historic masonry buildings based on measurements of their natural frequencies and numerical simulations. The modelling of the brittle nonlinear behaviour of masonry is carried out on the macro-level. As an example, a recently completed investigation of the seismic behaviour of the Aachen Cathedral is given, this being the first German cultural monument to be included in the UNESCO cultural heritage list in 1978. Its construction goes back to the 9th century a.d. and it is considered as one of the finest examples of religious architecture in Central Europe. The investigation is based on measurements of the natural frequencies at different positions and numerical simulations using a detailed finite element model of the Cathedral.     

A stochastic model of surface contaminant releases to support assessment of site contamination at a former industrial site

An industrial site is usually contaminated by accidental (and occasionally intentional) releases of pollutants to the environment from various operations carried out on that site. Consequently, the pattern of contamination created during the life of the site depends in part, at least, on the pattern of operations. Thus, the assessment of the pattern of contamination over the site should be improved: if it is possible to identify the pattern of operations on the site, the duration of the different activities and the perceived likelihood of releases from the different operations. A stochastic model has been developed that can be used to simulate alternative realizations of contaminant releases (duration, extent and timing). The model employs release zones associated with particular activities or groups of activities on the site and the areas of each of the zones may be independent or overlapping. The period of activity in each zone is obtained from the site records, while the likelihood and extent of contamination in each zone is inferred from an analysis of the contamination data obtained by point sampling. The form of the model, the method of inference of the model parameter values from the site data and the application of the model to the study site are presented. The release model has been developed as part of a suite of stochastic models for site ground contamination analysis. The stochastic soil and transport models and the application of the integrated modelling system are described in separate papers.     

Stochastic generation of hourly rainstorm events

Occurrence of rainstorm events can be characterized by the number of events, storm duration, rainfall depth, inter-event time and temporal variation of rainfall within a rainstorm event. This paper presents a Monte-Carlo based stochastic hourly rainfall generation model considering correlated non-normal random rainstorm characteristics, as well as dependence of various rainstorm patterns on rainfall depth, duration, and season. The proposed model was verified by comparing the derived rainfall depth–duration–frequency relations from the simulated rainfall sequences with those from observed annual maximum rainfalls based on the hourly rainfall data at the Hong Kong Observatory over the period of 1884–1990. Through numerical experiments, the proposed model was found to be capable of capturing the essential statistical features of rainstorm characteristics and those of annual extreme rainstorm events according to the available data.     

Early stage of critical clusters growth in phenomenological and molecular dynamics simulation models

The growth of critical clusters is discussed in the paper according to the classical and molecular dynamics (MD) approaches. A new formula for molecule numbers in critical clusters has been derived within the framework of the classical approach. A set of equations controlling the early stage of growth in a neighborhood of a critical size is presented. As far as molecular dynamics simulation is concerned, a computational technique based on the DL_POLY code is described in brief. Computation results are presented concerning cluster formation of H₂O vapor, distribution of clusters versus time, cluster growth and radial density distribution of isolated clusters. A comparison with the classical results is made for a case of dense vapor, where the mechanism of strong condensation is predominant. The Hertz–Knudsen formula seems to be verified by the molecular dynamics results.     

“2003.3”辽宁暴雪及其中尺度系统发展和演变

利用中尺度数值模式MM5V3.6和6 h一次的全球再分析NCEP资料,对2003年3月1—2日发生在辽宁的暴雪过程进行了数值模拟试验,着重分析和讨论了这一过程中中尺度系统的发生、发展和结构演变特征。结果表明:MM5V3.6能够成功地模拟中尺度暴雪的各个要素,由于低空辐合,高空辐散,导致上升运动加强以及低层正涡度中心的产生和维持,由此产生的垂直方向上水汽凝结是此次暴雪的形成机制。     

Product study of the reaction of OH radicals with isoprene in the atmosphere simulation chamber SAPHIR

Atmospheric oxidation of isoprene and its oxidation products methacrolein (MACR) and methyl vinyl ketone (MVK) have an important impact on the photochemical activity in the boundary layer, in particular in forested areas. The oxidation of isoprene by OH radicals was investigated in chamber experiments conducted under tropospheric conditions in the atmosphere simulation chamber SAPHIR at the Research Center Jülich. The aim was to determine the product yield of MVK and MACR in the OH-induced isoprene oxidation and the rate constant of their reaction with OH under real atmospheric conditions. The recently published updated degradation scheme for isoprene from Geiger et al. (2003) was used to determine rate constants and product yields. The fractional yields in the isoprene peroxy radical reaction with NO were found to be 0.41±0.03 for MVK and 0.27±0.03 for MACR. The rate coefficient for MACR with OH was found to be in very good agreement with the recommended value of IUPAC Atkinson (Atkinson et al., 2005). while the rate coefficient for MVK with OH was 27% lower.     

爆破动力作用下边坡稳定性的积分解法与应用

岩质边坡在爆破开挖过程中的稳定问题是一个亟待解决的重要问题。对实际工程进行监测,得到适合该地区的能反应高程效应的爆破地震波传播规律,并采用拟静力法计算爆破地震惯性力,提出边坡在爆破动力作用下稳定安全系数的新计算方法———积分法,同时使用MATLAB程序搜索边坡最危险滑裂面并计算最小安全系数。实例证明,此方法是分析边坡动力稳定性的有效方法之一。