Middle Yangtze sea-basin over Paleozoic-Mesozoic transition--Sedimental continuity and environmental catastrophe

On the centimeter scale of lithologic change,we conduct poly-statistic analysis on the sedimentary behavior and dynamic features of the stratigraphic sequence from upper Dalong formation to lower Daye formation,which across the Permian-Triassic boundary in East Hubei.From the perspective of stochastically dynamic system,the depositional process of upper Dalong formation can be regarded as a stable Markovian process with weakly stratigraphic correlation and randomly lithologic alteration.Compared to it,the depositional process of lower Daye formation was unstable Markovian process with much closer stratigraphic correlation and ordered lithologic change.As for the replacement style of the sedimental cycle,the former was chaotic,while the latter was periodical.Otherwise,although the overall depositional process of the two formations was continuous,their dynamic characteristics were obviously different.So this P-T sedimental boundary can also be regarded as a dynamic limit.It was a kind of depositional reaction in response to a catastrophic alteration when the geological environment was in continuous change but came over a certain threshold state.     

新形势下中国地震预报的发展战略

简述了各国科学家近年来对地震预报可能性的争论,结合中国20多年的经验讨论了新形势下中国地震预报的发展战略问题.     

Nonlinear behavior on an ozone photochemical system in the stratosphere

A nonlinear box system describing ozone photochemistry in the stratosphere is presented. Influences of pollutants, such as odd chlorine (Cl_x) and odd nitrogen (NO_x) discharged by human activities, on photochemical states of the system are investigated in detail. The results show that the solutions of the box system constitute a ‘cusp’ catastrophe manifold in the state-parameter space. An increase of about 30% for Cl_x source strength or a decrease of about 30% for NO_x source strength from their current level may lead to catastrophic transition and results in a reduction of ozone concentration about 50 times. Project supported by the National Natural Science Foundation of China and Laboratory for Aeronomy and Global Environmental Observation of IAP.     

巨型古滑坡的稳定性评价及发展趋势分析

利用尖点突变模型进行滑坡稳定性评价,再以集合经验模态分解、GM(1,1)模型和支持向量机等方法为基础,构建滑坡变形预测模型。以变电站滑坡为例进行分析,结果表明,各监测点的突变特征值均大于0,即处于稳定状态;所得变形预测结果的平均相对误差均较小,验证了本文预测模型的有效性;通过外推预测,发现滑坡变形仍会进一步增加,稳定性变差。     

大坝变形失稳的尖点突变模型

基于大坝变形失稳的简化力学模型,考虑裂隙的非线性应变软化和渗水软化,根据突变理论推导了大坝变形失稳的尖点突变模型,并利用该模型对大坝变形失稳的机理和力学条件进行了分析,从整体上深化了对大坝变形失稳机制的认识。     

浅埋偏压隧道洞口段软弱围岩失稳突变理论分析

含有断层的浅埋偏压隧道的断层错动引起围岩失稳是一个由渐变到突变的过程,具有非连续跳跃的特征,可以采用突变理论分析围岩破坏方式。以沪-昆客运专线长-昆湖南段CKTJ-Ⅸ标段某隧道洞口穿越断层破碎带为工程背景,根据围岩失稳情况,建立隧道穿越断层段的力学模型,构建断层围岩系统的总势能函数,求出突变模型的标准型式和分叉集方程;将拱顶下沉变形随时间变化的函数展开为泰勒级数,建立隧道围岩稳定状态判别式,实现突变模型和监测数据的融合。研究结果表明,围岩拱顶沉降变形随时间变化的函数与围岩失稳突变模型之间存在良好的转化关系;根据围岩失稳突变判据得出的围岩失稳状态与实际围岩破坏情况基本吻合,且判别式的组成型式简单,对于判断含有断层的浅埋偏压隧道围岩稳定性具有较强的实用性;判别式的大小与围岩的破坏程度之间存在一定的关联。     

基于突变理论的滑坡危险性评价

滑坡危险性评价与预测是滑坡灾害防治中的首要任务,科学合理地评价滑坡危险性十分重要。以岩桑树水电站库区发育的潜在滑坡为例,据其特有的地质环境条件,选取坡体风化程度、斜坡坡度等9个影响因素作为滑坡危险性评价的指标,并建立分级标准将滑坡危险性分为轻度危险、中度危险、重度危险和极度危险4个等级。将突变理论运用到滑坡危险性评价中,从而建立了新的稳定性评判模型。基于突变级数法的滑坡危险性评价方法,综合考虑了各评价指标间的相关性,真实地描绘了滑坡系统的内在机制。实例分析结果表明,该方法评判结果准确率高,可为滑坡的防治提供依据。     

突变理论在地震资料解释中的应用

阐述了尖点突变理论,建立了地震信号尖点突变模型并转化为尖点突变的标准形式,在时间域内提取突跳势、突跳时间;在频率域内提取突跳势、突跳次数等参数。运用突变理论对实际地震资料进行构造解释表明:突跳参数曲线上异常的位置与断层的位置有关,为地震资料解释提供了一种新的途径。      

台风“飞燕”登陆前后的运动特征

通过对2001年台风“飞燕”登陆前的雷达回波和地面加密观测资料的分析表明：兴化湾地形作用使微型小台风近海突然加速折向兴化湾移动，微型小台风在临近登陆时风速将出现跳跃突变，其隐蔽性的灾害特征突出。指出制作微型小台风登陆前风速的定时定量预报的必要性。     

中国东部燕山期岩石圈-软流圈系统大灾变与成矿环境

中国东部在燕山期发生了岩石圈－软流圈系统（ＬＡＳ）大灾变事件,并识别出被扰动的ＬＡＳ的两种类型,即在搞压造山环境下的岩石圈巨大减薄与巨大增厚作用;它们分别对应相关的安第斯型和海西型成矿作用,大量的新生,热地幔物质和再活化的热的下地壳物质取代,加热和注入冷的岩石圈和地壳是燕山期成矿大爆发的基因和基本的深部环境,再活化和活动的岩石尺度的不连续带是成矿带的良好储矿空间,巨大的岩浆－流体－成矿系统是形成巨