Development of joints and shear fractures in the Kuqa depression and its implication to regional stress field switching

The superimposed basin must have undergone the changes of regional stress field. Study on the nature and switch of regional stress field of superimposed basin is very useful to understanding its stress state and tectonic events during its formation and evolution. As sensitive markers of small stress changes, joint and shear fracture, characterized by consistency of orientation over wide area, can be used to reconstruct paleostress state and its evolution. Detailed observations and analysis on the orientations, geometrical patterns, sequences of joints and shear fractures and their chronological relation to faults and folds show that, the NEE-SWW systematic joints and NNW-SSE systematic joints developed in the Mesozoic and Cenozoic strata are much more prominent than NW-SE systematic joints and shear fractures with different orientations. And the NWW-SEE and NW-SE systematic joints formed later than NEE-SWW systematic joints but earlier than shear fractures with different orientations. According to the relationships between joint and shear fractures and stress, the NEE-SWW systematic joints are inferred to result from lateral weak extension caused by the late Cretaceous regional uplift, while the NNW-SSE and NW-SE systematic joints are interpreted as syn-tectonic deformation relating to strong N-S compression in the Neogene. But some conjugate shear fractures occur probably due to sinistral strike-slip faulting in the Kuqa depression. At the beginning of the Neogene, the stress field changed and the maximal principal stress σ1 switched from vertical to horizontal.     

Studies on wind environment around high buildings in urban areas

High buildings or architectural complex in urban areas remarkably distort the urban surface wind fields. As the air flow approaches,local strong wind may appear around the buildings. The strong wind makes the pedestrians on sidewalks, entrances and terrace very uncomfortable and causes the pedestrian level wind environment problem. In this studies, hot-wire wind measurement, wind scouring in wind tunnel and numerical computation were carried out to evaluate the wind environment of tall buildings in the prevailing flow conditions in Beijing areas. The results obtained by three techniques were compared and mutually verified. The conclusions drawn from three approaches agree with each other. Also the advantages and limitations of each method were analyzed. It is suggested that the combination of different techniques may produce better assessment of wind environment around high buildings.     

云南墨江金矿含镍金绿色蚀变岩的构造地球化学特征及时空演化

采用构造变形筛分、同位素地球化学定年约束和构造蚀变岩的常量 微量元素地球化学研究等方法,对墨江镍金矿床中含金镍绿色蚀变带进行详细研究,探讨其形成和时 空演化规律,以及与金、镍成矿关系,提出本区含镍金绿色蚀变带形成与演化可分为三个期次:早期含镍金绿色蚀变带形成于(251 9±4 32)Ma,产于韧性剪切带中,形成含铬绢云母 绢云母(S2)组成的切层剪切面理;中期含镍金绿色蚀变岩形成于燕山早期(169 37～180 6Ma),产于高角度脆韧性剪切带中,形成铬绢云母 含铬绢云母组成的透入性剪切面理换(S3)和绿泥石拉伸线理;晚期含金绿色蚀变糜棱岩形成于燕山晚期(71 14～149 98Ma),产于左旋走滑脆韧性剪切带中,发育铬伊利石(S4)和铬绿泥石(S4)组成透入性剪切变形面理置换,与脆韧性剪切带的主体产状一致,韧性剪切构造带内发育,走滑构造带中十分发育,形成褶皱变形带(倾竖褶皱、鞘褶皱)及含金蚀变岩。     

峰局五矿下组煤带压开采的可行性与建议

峰局五矿是多年开采的老矿。近些年，随着开采深度的不断增加和开采层次的逐渐下移，来自底部岩溶高承压水的威胁日趋严重，实际生产能力逐年下降。下组煤能否开采是关系到矿井生存与发展的大问题。作者根据多年的研究成果和工作实践，就下组煤带压开采的可行性，谈一些看法和建议。     

Estimated mass and stiffness matrices of shear building from modal test data

A method that estimates mass and stiffness matrices of shear building from modal test data is presented in this paper. The method depends on only measurable points that are less in number than the total structural degrees of freedom, and on the first two orders of structural mode measured. So it is applicable to most of the general test. Based on this method modal data of unmeasurable points are estimated, then global mass and stiffness matrices of structure are obtained by using the first two orders of modal data. Taking advantage of iteration the optimum global mass and stiffness matrices are gained. Finally, an example is studied in this paper. Its result shows that this method is reliable. © 1998 John Wiley & Sons, Ltd.     

Fermat猜想的两个等价命题

对每个奇素数p,我们提出了关于p的两个命题:(I)不存在正整数m和n,使代数曲线f(y)=y~3-(2m+1)y-2n的三个零点同时为p方有理整数;(I)不存在正整数m,使不定方程x~2+3y~2=4(2m+1)具有三组正整数解x_i,y_i(i=1,2,3),满足x_1=x_2+x_3,x_1~2+x_2~2+x_3~2=6(2m+1)。本文旨在证明(I)及(I)都与关于素数p的Fermat猜想等价。     

采用物理指标评价黏性土承载力的方法研究

利用大连长兴岛葫芦山湾海域勘察资料,对742组黏性土的主要物理指标与承载力fo的对比数据,进行了相关分析。建立了黏性土主要物理指标与承载力fo之间经验关系4个。提出了实际勘察工作中承载力特征值fak的评价方法,为利用物理指标评价黏性土承载力建立了理论基础。     

贵州施秉白云岩溶蚀特性及孔隙特征实验研究

以贵州施秉白云岩为研究对象,从宏观和微观角度分析白云岩的溶蚀特性及孔隙特征,结果显示:(1)在众多影响施秉喀斯特发育的因素中,矿物成分是最基本的内因,水是最关键的外因,孔隙结构起辅助作用。(2)极细晶白云岩的单位表面积溶蚀量一般大于细晶白云岩的,在晶粒相同的情况下,白云岩的溶蚀量与Ca O和Mg O的含量分别成正比,且Mg O的含量影响较Ca O大。(3)施秉白云岩溶蚀速率不仅受岩石矿物颗粒粒径大小的控制,还受岩石内部孔隙结构特征的影响,颗粒粒径越大,孔隙度越高,连通性越好,越有利于水溶液进入,溶蚀量也就越大。(4)施秉白云岩的溶蚀特性是多种因素综合作用的结果,必须把各个因素分离开来,从宏观和微观角度逐个作详细的分析研究,然后综合起来,才能对喀斯特发育规律有更深入的了解。     

一种新型的建筑物修复或抗震加固方法

叙述了采用高强度纤维／环氧树脂复合材料对建筑物进行修复或抗震加固方法的特点、施工方法,实例表明该方法有广泛的应用前景,指出,该方法对保证人民财产安全及搞好防震减灾工作有积极作用。     

速度传感反馈地震计的参数稳定性分析

从理论上定量分析机械摆和环路滤波等开环诸参数变化对速度传感反馈地震计闭环参数的影响.研究指出,在环路设计中可半自由选取的开环阻尼取值对参数稳定性有重要影响.过大或过小的开环阻尼取值均可能造成参数稳定性急剧变差,影响地震计在只标不调的状况下长期连续稳定工作.