Effect of polypropylene fibre and lime admixture on engineering properties of clayey soil

In order to reduce the brittleness of soil stabilized by lime only, a recent study of a newly proposed mixture of polypropylene fibre and lime for ground improvement is described and reported in the paper. To investigate and understand the influence of the mixture of polypropylene fibre and lime on the engineering properties of a clayey soil, nine groups of treated soil specimens were prepared and tested at three different percentages of fibre content (i.e. 0.05%, 0.15%, 0.25% by weight of the parent soil) and three different percentages of lime (i.e. 2%, 5%, 8% by weight of the parent soil). These treated specimens were subjected to unconfined compression, direct shear, swelling and shrinkage tests. Through scanning electron microscopy (SEM) analysis of the specimens after shearing, the improving mechanisms of polypropylene fibre and lime in the soil were discussed and the observed test results were explained. It was found that fibre content, lime content and curing duration had significant influence on the engineering properties of the fibre–lime treated soil. An increase in lime content resulted in an initial increase followed by a slight decrease in unconfined compressive strength, cohesion and angle of internal friction of the clayey soil. On the other hand, an increase in lime content led to a reduction of swelling and shrinkage potential. However, an increase in fibre content caused an increase in strength and shrinkage potential but brought on the reduction of swelling potential. An increase in curing duration improved the unconfined compressive strength and shear strength parameters of the stabilized soil significantly. Based on the SEM analysis, it was found that the presence of fibre contributed to physical interaction between fibre and soil whereas the use of lime produced chemical reaction between lime and soil and changed soil fabric significantly.     

基于夜间灯光数据的环渤海地区城市化空间模式和过程研究

1 Introduction Urban agglomeration is a system of cities, supporting by the modern transportation and information network in the system, these cities, with different characteristics, types, sizes and hierarchies, interact with each other, and one or two …     

气候变化对中国大雾的影响

1 Introduction The global environmental problem caused by climatic warming has attracted increasing attention of the scientific communities, the public and governments of various countries. The mean temperature of the recent decade is the highest of the p…     

中国近海初级生产力的遥感研究及其时空演化

1 Introduction Ocean primary productivity controls the exchange of carbon dioxide at the air-sea interface and plays an important role in the global carbon cycle and climate change. Most oceanographic research on primary productivity has focused on the ma…     

塔里木地区寒武纪岩相古地理

塔里木地区是以当今的塔里木盆地为主体并包括其周边山地的广大地区,北至中天山,南至西昆仑山,西至我国国界,东至阿尔金山,面积逾100万km2。在39个露头剖面和钻井剖面的各种单因素定量及定性资料的基础上,采用单因素分析多因素综合作图法,编制出了塔里木地区寒武系下、中、上统的各种单因素图及相应的寒武纪早、中、晚世的岩相古地理图。这些岩相古地理图最主要的特征是定量,即每个古地理单位的划分和确定都有确切的定量资料与定量的单因素图。这种定量的岩相古地理图在塔里木地区还是首次出现。在早寒武世,塔里木地区是一个碳酸盐岩台地,其中散布着准滩、云坪和膏盐湖。其北侧和东北侧是南天山和塔东硅岩石灰岩泥岩盆地。其南侧是昆仑台地,其中有2个小陆地。其东南侧有阿尔金陆。中寒武世和晚寒武世的岩相古地理格局与早寒武世相似,但陆地面积逐渐缩小,盆地面积逐渐扩大,塔里木碳酸盐岩台地变化不大。从早寒武世到晚寒武世是一个逐渐的海进过程。     

QTPV Data Model and Algorithm and Its Application to Geological Exploration Engineering

3D spatial data model and simulating are the core of 3D GIS can be adopted in different domains. A data model based on Quasi Tri-Prism Volume (QTPV) has been proposed. QTPV definition and its special cases have been discussed. Using QTPV and its special cases, irregular natural geological bodies and regular subsurface engineering can be described efficiently. The proposed model is composed of five primitives and six objects. Data structures and topological relationship of the fives primitives and three objects describing stratigraphy are designed in detail Some schemes are designed for the QTPV modelling of stratigraphy and subsurface engineering according to modelling data. The model manipulation method of QTPV cutting by an arbitrary plane is discussed. Using VC 6.0 programming language integrated with SQL database and OpenGL graphic library under windows environment, a system prototype 3DGeoMV has been developed. The experiment result shows that the QTPV model is feasible and efficient in modelling subsurface engineering.     

东昆仑阿尼玛卿地区古特提斯火山作用和板块构造体系

东昆仑阿尼玛卿蛇绿岩带标志古特提斯洋关闭后的板块缝合带。在该缝合带及周围识别出4套与洋盆扩张和俯冲作用有关的火山岩,由南至北,分别为洋底玄武岩、岛弧火山岩、弧后盆地玄武岩和后碰撞火山岩。板块构造体系说明洋壳俯冲极性从南向北。已有年代学证据表明:阿尼玛卿洋盆的开启时代至少可以早到晚石炭世(308Ma),洋盆关闭可能在早三叠世;岛弧火山岩的时代为晚二叠世(260Ma);弧后盆地火山岩的时代为早中三叠世;后碰撞火山岩的时代为晚三叠世。三叠纪沿缝合带及其北部形成了一系列巨大的左旋走滑断裂系,包括东昆仑南缘左旋走滑断裂(200~220Ma)、阿尔金断裂的早期走滑剪切断裂系(220~230Ma)以及南祁连南缘巨型左旋走滑断裂(240~250Ma)。认为它们形成于阿尼玛卿古特提斯洋的关闭和斜向碰撞作用,但主要在俯冲板块折返阶段或逆冲岩片的抬升阶段,其时也是后碰撞岩浆活动和火山喷发阶段。     

胶北晚中生代煌斑岩的岩石地球化学特征及其成因研究

胶北煌斑岩分别采自龙口、烟台和威海地区，包括拉辉煌斑岩、斜闪正煌岩和角闪煌斑岩，煌斑岩K—Ar全岩年龄变化于89．3～169．5Ma，为晚中生代岩浆活动的产物。在岩石化学组成上，SiO2=42．02％～54．95％，以钙碱性系列为主．岩石以富集大离子亲石元素（LILE）（Ba，U，K，Th）和LREE，亏损高场强元素（HFSE）（Nb，Ta和Ti）为特征，Mg^#=33．9～53．9，Eu／Eu^＊=0．71～0．89，^87Sr／^86Sr初始比值0．707642～0．709791，εNd（t）为-17．6～-10．4，^206Pb／^204Pb=37．588～38．431，^207Pb／^204Pb=15．423～15．531，^206Pb／^204Pb=17．204～18．179。表明煌斑岩源自俯冲陆壳（扬子下地壳）在地幔源区发生交代作用时形成的富集型地幔的部分熔融体．考虑到煌斑岩具有大陆边缘弧玄武岩的特征，我们认为煌斑岩在成因上同样与古大洋板块的俯冲作用有关，为碰撞后弧岩浆作用形成的脉岩。     

一次“高影响天气”的弱降雪过程的数值研究

该文对2001年12月7日下午北京的一次弱降雪天气过程进行了诊断分析和数值模拟研究。诊断结果表明:北京地区由于受500 hPa小槽东移及850 hPa东移小高压后部带来的来自东海和南海的偏南暖湿气流共同影响，造成降雪。数值模拟结果显示:MM5模式对这次降雪过程具有较好的模拟能力，不仅模拟出了北京地区的降雪量，而且对这次过程大尺度背景场的演变、触发机制和水汽源有很好的表述。利用诊断分析和数值模拟结果，对这次弱降雪过程引起交通大阻塞的可能因素进行了探讨，说明建立城市预警系统的迫切性。     

相对湿度对气溶胶辐射特性和辐射强迫的影响

采用已有的气溶胶折射指数等资料 ,计算了在不同的相对湿度条件下硫酸盐气溶胶的辐射特性。结合两种不同化学输送模式 (CTM )的模拟结果及LASGGOALS/AGCM模式 ,模拟估算了考虑相对湿度影响后全球硫酸盐气溶胶的辐射强迫。结果表明 :(1)随着相对湿度的增加 ,硫酸盐气溶胶的质量消光效率因子在短波波段有所减小 ,单次散射反照率仅在长波波段有所增加 ,不对称因子在整个波段均有所增加 ;(2 )用两个CTM资料模拟辐射强迫的结果相差较大 ,其全球平均辐射强迫分别为 - 0 .2 6 8和 - 0 .816W/m2 ;(3)在考虑相对湿度的影响后 ,硫酸盐气溶胶辐射强迫的分布类型与相应干粒子的强迫分布类型基本相同 ,但全球平均的强迫值减少了 6 %左右。