藏东巴青县北部酉西岩组构造片理形成及构造意义

西藏巴青县以北酉西岩组主要由石英构造片岩、钠长石英构造片岩、白云母石英构造片岩组成,构造片理为近水平韧性剪切作用产物。宏观上构造片理构成了宽缓的背形、向形褶皱构造,构造片理上广布一期透入性拉伸线理,将构造片理展平,分布在透入性片理上的线理具明显优选方位,方向为280~100°。根据微观构造分析,韧性剪切指向为自西向东运动,构造片岩内发育多硅白云母。多硅白云母电子探针分析结果认为其形成环境为低温高压蓝片岩相,变质温度确定为320~500℃、压力0·6~1·1GPa。多硅白云母40Ar/39Ar测年结果为(230±1)Ma,为中三叠世末期。酉西岩组构造片理(韧性剪切作用)与查吾拉—吉塘印支期构造岩浆带形成密切相关。     

南京砂的结构特性与地铁地基液化判别

与圆颗粒的标准砂相比较,片状结构的砂的动力特性更为复杂,用规范法进行液化判别时会误判。为了将砂土片状结构特性考虑到判别过程中,建议了一个更为合理的Ncr 的经验公式,并利用该公式对南京地铁玄武门-南京站区间的砂土层进行液化判别,该区间会发生中等程度为主的液化,最后,将液化判别结果与规范法和室内动力实验结果相比较,分析发现,在南京地铁进行液化判别时,必须考虑片状结构特性对于液化影响;同时,给出了平均液化势随深度的变化情况,以及考虑砂土结构特性对判别结果的影响系数随土层深度的关系,提高了判别的精度。     

西藏东部嘉玉桥变质杂岩中片理化岩组主期面理形成及构造意义

西藏东部嘉玉桥变质杂岩中片理化岩组剪切运动方向为ＳＥ１４０°—ＮＷ３２０°,应变测量求得富林参数Ｋ平均值为２１３,表明主期面理变形为单剪与收缩机制的复合产物。由石英位错密度估算其差应力值平均为１４９５ＭＰａ,白云母形成温度３８３℃。经４０Ａｒ３９Ａｒ法年龄测定,获得主期变形时间为（１６４７±１３３）Ｍａ（白云母）～（１６６２７±０９９）Ｍａ（角闪石）。因此,嘉玉桥片理化岩组主期变形与区域上班公湖—怒江缝合带的形成演化有着密切的关系。     

An investigation into strength and porous properties of metamorphic rocks in the Himalayas: A case study

If a rock is porous in nature, the genetic complexity associated with its petrofabric makes it difficult to predict its behavior. Here, a comprehensive study of the porous nature, physical and geotechnical responses of three varieties of schist, i.e. quartz mica schist, quartz mica schist with quartz veins and biotite schist of low grade metamorphism obtained from Nathapa-Jhakri hydroelectric project site in the foot hills of Himalayas, India, has been presented. The porous nature of the schists has been brought out through the Mercury Intrusion Porosimetry (MIP) testing and strength behavior through uniaxial testing. Through an experimental invesigation, the porous nature and pore size distribution parameters from MIP, which are closely related to the strength and performance of metamorphic schistose rocks, have been studied. The significance of the porous nature and its response for consideration in the design is emphasized.