贵州凝冻的时空分布特征和环流成因分析

以贵州省47个气象地面站1951—1996年的冬季凝冻指数为基本研究对象,分析凝冻指数场的分布特征及时间系数的演变规律,并分析了第一时间系数与冬季500hPa高度的相关场分布特征。根据第一时间系数的变化,确定了5个重凝冻年和5个无凝冻年,用合成分析方法分析了重凝冻年和无凝冻年的冬季平均500hPa高度场的分布特征。结果表明：重凝冻年与无凝冻年差异最显著的地区在欧亚地区,重凝冻年呈“北高南低”型的距平分布,无凝冻年呈“北低南高”型的距平分布。     

Cyclone Phase Space Characteristics of the Extratropical Transitioning Tropical Cyclones over the Western North Pacific

The cyclone phase space (CPS) method has been utilized to evaluate the extratropical transition (ET) of tropical cyclones (TCs) in many recent publications. However, these studies mainly focused over the North Atlantic basin. In this paper, the CPS characteristics of all the cyclones over the western North Pacific are investigated and discussed, with three parameters calculated from the best-track data of the Regional Specialized Meteorological Center in Tokyo and the Japanese 25-yr reanalysis data. It is concluded that most TCs over the western North Pacific possess the non-frontal and warm-core structure, while a larger number of cyclones that have undergone ET hold the frontal and cold-core structure. The spatial pattern of the CPS parameters indicates that the areas of tropical and extratropical cyclone activities could be demarcated by 30°N. The composite and individual series of three parameters of the CPS indicate that the transformation of −V _T^U from positive to negative leads to the start of ET, and could be considered as a potential predictor in operationally forecasting an ET event.     

The Time-Frequency Energy Attenuation Factor and Its Application on the Basis of Gauss Linear Frequency-Modulated Continuous Wavelet Transform

Based on the Gauss linear frequency-modulated wavelet transform, a new characteristic index is presented, namely time-frequency energy attenuation factor which can reflect the difference features of waveform in earthquake focus mechanism, wave traveling path and its attenuation characteristics in focal area or near field. In order to test its validity, we select the natural earthquakes and explosion or collapse events whose focus mechanisms vary obviously, and some natural earthquakes located at the same site or in a very small area. The study indicates that the time-frequency energy attenuation factors of the natural earthquakes are obviously different with that of explosion or collapse events, and the change of the time-frequency energy attenuation factors is relatively stable for the earthquakes under the normal seismicity background. Using the above-mentioned method, it is expected to offer a useful criterion for strong earthquake prediction by continuous earthquake observation.     

An Effective Method for Free Vibration of Plate on Elastic Half Space

The vibration analysis of a plate on an elastic foundation is an important problem in engineering. It is the interaction of a plate with the three-dimensional half space and the plate is usually loaded from both the upper and lower surfaces. The contact pressure from the soil can not be predefined. According to Lambs solution for a single oscillating force acting on a point on the surface of an elastic half space, and the relevant approximation formulae, a relation between the local pressure and the deflection of the plate has been proposed. Based on this analysis, the reaction of the soil can be represented as the deformation of the plate. Therefore, the plate can be separated from the soil and only needs to be divided by a number of elements in the analysis. The following procedure is the same as the standard finite element method. This is a semi-analytical and semi-numerical method. It has been applied to the dynamic analysis of circular or rectangular plates on the elastic half space, at low or high frequency vibration, and on rigid, soft or flexible foundations. The results show that this method is versatile and highly accurate.     

复杂环境下深基坑优化设计探讨

目前城市空间日益紧缺,在城市内进行基坑开挖面临的狭小空间、复杂环境问题也逐渐成为基坑工程设计的重点难点;同时,在工程设计整体向地下要空间的思路下,基坑大多开挖深度较深。结合北京市昌平区某基坑工程设计案例,介绍了复杂环境下基坑优化设计,该基坑紧邻周边建筑物,周边建筑物基础埋深、基础形式、建筑年代、使用功能各异,根据环境条件,设计采用了"多标高+降台阶+不同参数"的桩锚支护体系,同时在施工过程中实施动态设计管理,支护结构工艺简单、节约造价、动态灵活,同时保证了基坑工程安全,对类似工程具有借鉴作用。     

塔中北斜坡鹰山组碳酸盐岩溶蚀的模拟实验研究

为了研究碳酸盐岩的微观溶蚀机理,本文采用溶蚀实验和镜像观察的方法,研究了塔中北斜坡鹰山组3种类型碳酸盐岩的溶蚀过程及微观溶蚀特征。结果表明:在相同实验条件下,亮晶生屑灰岩、云质灰岩和泥晶颗粒灰岩的溶蚀量基本一致。由于对物质成分和岩石微结构的选择性溶蚀,它们的微观溶蚀特征存在明显差异。亮晶生屑灰岩和泥晶颗粒灰岩样表面整体被溶蚀降低。云质灰岩样表面方解石部分整体被溶蚀降低,形成铸模孔,白云石溶蚀成蜂窝状溶蚀孔,并突出岩石表面,白云石晶间缝溶蚀加大且相互连通,这对油、气和地下水储渗具有重要意义。      

关于弹性力学半无限问题的注记

根据两个合理的判断依据,对弹性力学中的楔形体、半平面体、圆锥体和半空间体等经典解答进行了比较分析,发现了半无限平面应变问题和半空间体问题解答之间的关系;通过对解答之间的关系进行研究分析指出,弹性力学中的半无限平面体的符拉芒解答和半空间体的布希涅斯克解答存在局限性。对半无限地基、底部完全位移约束的有限深地基和底部光滑刚性支承的有限深地基在水平表面作用无限均布压力时的应力和位移分量进行了比较分析,认为底部完全位移约束的有限深地基模型较其他两种地基模型更合理些。     

试论花岗质深成岩体的复合定位机制及定位空间问题

大陆地壳中巨量花岗岩体的定位机制及定位空间是一个长期急论的问题,已提出十余种机制,但都困难以解决定位空间面引起争议,近年来,人们认识到岩体定位及获取空间是多种机制共存的复合定位机制,这是今后需进一步研究的新课题,笔者提出的复合定位机制可概括为主动膨胀,构造扩展,岩浆侵吞作用３个基本端元机制的构成的复合,可用三角图解表述,并以具体研究实例进行了论述。     

岩土材料剪切破坏点安全系数的研究

剪切破坏是岩土材料失效的一种主要的形式。针对这种形式强度安全考虑的点安全系数可以考察结构中各部分的安全情况,是结构安全分析的一种重要参考,尤其在由关键点控制的结构中显得尤为重要。摩尔库伦剪切破坏准则在岩土材料研究中被广泛应用,将基于该准则的点安全系数定义在三维广义Mohr空间中推广,得到了适用于不同剪切破坏失效准则的点安全系数定义,同时,在三维广义Mohr空间中推导,得到了岩土材料剪切破坏最小点安全系数的求解方法;最危险截面上偏应力和剪应力的关系,该最危险截面与最小点安全系数对应;以及在一定整体安全度下的失效条件。应用该定义及方法,可以研究判断不同岩土材料剪切破坏的安全情况,从而提高工程建设质量。     

一种特殊的储集空间成因机制：断裂—地震—高压水射流作用

本文以河套盆地临河坳陷扇三角洲相砂砾岩储层为研究对象,揭示一种与断裂构造相关的储集空间形成的潜在机制。研究表明,河套盆地临河坳陷扇三角洲相砂砾岩纵向上往往表现为破碎段和完整段相间分布的特征。破碎段砂砾岩破碎严重,仅残留少量疏松易碎的岩石碎块,其中碎屑颗粒发生明显碎裂,而碎屑颗粒之间的填隙物多已缺失。完整段砂砾岩在宏观上未发生明显破碎,但镜下分析表明,在靠近破碎段的砂砾岩中不均匀地发育一些粒间孔和粒内裂缝孔,并以条带状、不规则斑块状、近圆形或椭圆形斑点状等多种形态集中分布。这些特殊储集空间的形成很难由简单的"断裂破碎"模式加以解释。基于宏—微观岩相学的系统研究,本文提出"断裂—地震—高压水射流"成因机制:(1)原生沉积的扇三角洲相巨厚层状砂砾岩为泥质或同生泥晶—粉晶方解石填隙,致密无孔,后因盆内断裂切割而发生破碎,形成构造破碎带这一最为主要的储集空间。(2)后期断裂活动促使地震活动频发,引起断裂带内地下水的激荡性运动,形成断裂带内及向两侧的高压流体射流。高压流体射流的冲洗作用使碎屑颗粒间泥质及泥晶—粉晶方解石填隙物被带走,形成冲洗粒间孔,同时使得碎屑颗粒通过撞击而发生碎裂。(3)高压流体充注使得颗粒脆性碎裂得以保留。